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PREVENTIVE  MEDICINE 
AND  HYGIENE 


PREVENTIVE  xMEDICINE 
AND  HYGIENE 

BY 

MILTON  J.   ROSENAU 

PHOFESSOR  OF  PREVENTIVE  MEDICINE  AND  HYGIENE,  HARVARD;    DIRECTOR  OF  THE  SCHOOL 

FOB  HEALTH  OFFICERS  OF  HARVARD  UNIVERSITY  AND  THE  MASSACHUSETTS  INSTITUTE 

OF  technology;    formerly  DIRECTOR  OF  THE  HYGIENIC  LABORATORY, 

U.  S.  PUBLIC    HEALTH    SERVICE,  ETC. 

WITH  CHAPTERS  UPON 

SEWAGE   AND   GARBAGE,  BY  GEORGE    C.  WHIPPLE,  PROFESSOR   OF  SANITARY    ENGINEERING, 

HARVARD 

VITAL     STATISTICS,    BY     JOHN     W.    TRASK,     ASSISTANT     SURGEON-GENERAL,      V.    S.      PUBLIC 

HEALTH     SERVICE 

MENTAL    HYGIENE,     BY    THOMAS    W.    SALMON,    MEDICAL     DIRECTOR,    NATIONAL     COMMITTEE 
FOR  MENTAL  HYGIENE,  ETC. 


SECOND  EDITION 
THOROUGHLY  REVISED 


NEW  YORK  AND   LONDON 
D.    APPLETON    AND     COMPANY 

1916 


Copyright,  1913.  1916,  by 
D.  APPLETON  AND  COMPANY 


Printed  in  the  United  States  of  America 


TO 

MY    WIFE 


PREFACE   TO   THE   FIRST  EDITION 

This  book  has  been  written  in  response  to  a  demand  for  a  treati.-c 
based  upon  modern  progress  in  hygiene  and  sanitation.  The  worls:  is 
planned  to  include  those  fields  of  the  medical  and  related  sciences 
which  form  the  foundation  of  public  health  work.  So  far  as  I  know, 
no  other  book  on  the  subject  covers  the  broad  field  considered  in  this 
volume.  The  progress  in  hygiene  and  sanitation  has  been  so  rapid  that 
the  subject  of  preventive  medicine  has  become  a  specialty,  and  its  scope 
has  become  so  broad  that  the  question  throughout  the  making  of  this 
book  has  been  rather  what  to  leave  out  than  Avliat  to  include.  The  facts 
here  brought  together  are  widely  scattered  in  the  literature  and  many  of 
them  are  difficult  of  access;  they  have  been  collected  for  the  convenience 
of  tlie  student  of  medicine  and  the  physician,  as  well  as  those  engaged 
in  sanitary  engiuecriiig  or  public  healtli  Avork. 

During  twenty-three  years  of  varied  experience  in  public  health 
work  it  has  been  Hiy  good  fortune  to  have  served  as  quarantine  officer, 
in  epidemic  campaigns,  in  epidemiological  investigations,  and  in  public 
health  laboratories,  at  home,  on  the  Continent,  and  in  the  tropics.  The 
fruits  of  these  experiences  are  reflected  in  this  book,  which  may  be  taken 
as  representing  my  personal  views  gained  in  the  field,  in  the  laboratory, 
in  the  classroom,  and  in  administrative  offices. 

It  is  wellnigh  impossible  to  prevent  or  suppress  a  communicable 
disease  without  a  knowledge  of  its  mode  of  transmission.  This  is 
the  most  important  single  fact  for  successful  personal  prophylaxis,  as 
well  as  in  the  general  warfare  against  infection;  therefore;,  the  com- 
municable diseases  have  been  grouped  in  accordance  with  their  modes  of 
transference.  Each  one  of  the  important  communicable  diseases  is  dis- 
cussed separately  in  order  to  bring  out  the  salient  points  upon  which 
prevention  is  based.  The  classification  adopted  is  believed  to  be  unique 
and  should  prove  helpful  to  those  who  are  especially  concerned  in  the 
prevention  of  infection. 

The  book  may  be  considered  in  t'wo  parts,  namely,  that  which  deals 

vii 


viii  PREFACE  ^IX)  FIRST  EDITION 

willi  ilic  person  (hygiene)  and  llial  which  (h'als  with  the  eiivinjinnent 
(sanitation).  The  first  part  includes  tlie  prevention  of  the  comniuiiicahlc 
diseases,  venereal  prophylaxis,  heredity,  immunity,  eugenics,  and  similar 
suhjects.  The  second  part  deals  with  our  environment  in  its  relation 
to  health  and  disease  and  includes  a  discussion  of  food,  water,  air,  soil, 
disposal  of  wastes,  vital  statistics,  diseases  of  occupation,  industrial 
hygiene,  school  hygiene,  disinfection,  quarantine,  isolation,  and  other 
topics  of  sanitary  importance,  as  well  as  subjects  of  interest  to  health 
officers.  All  the  important  methods  used  in  public  health  laboratories 
are  described. 

To  have  made  this  book  in  monographic  style  with  references  to 
authorities  for  every  statement  Avould  have  resulted  in  an  unwieldy 
work  of  impractical  size  and  form.  The  textbook  style  has  therefore  been 
adopted  and  citation  of  authorities  for  facts  that  are  now  well  estab- 
lished has  been  regarded  as  unnecessary.  In  this  respect  it  may  seem 
that  I  have  given  scant  credit  to  many  workers  from  whose  writings 
I  have  borrowed  results,  thoughts,  and  sometimes  words  or  even  sen- 
tences. At  the  end  of  each  chapter  will  be  found  a  list  of  references 
to  articles  or  books  that  I  have  esjDecially  drawn  upon,  and  I  desire  to 
acknowledge  my  obligations  to  these  sources  as  well  as  to  refer  the  reader 
to  them  for  further  study  of  particular  subjects.  I  have  also  drawn 
freely  upon  my  own  previous  writings  and  those  of  my  co-workers  in 
com23iling  this  book.  The  chapter  on  "Disinfection"  is  based  upon  my 
book  entitled :  "Disinfection  and  Disinfectants,"  published  by  P.  Blaki- 
ston's  Sons  &  Co.,  Philadelphia,  1902. 

I  have  received  generous  help  from  a  number  of  friends  and  it  is  a 
pleasure  here  to  acknowledge  especially  ni}^  obligation  to  Dr.  David  L. 
Edsall  for  reading  and  correcting  the  chapter  on  Diseases  of  Occupa- 
tions, to  Dr.  John  F.  Anderson  and  Dr.  Joseph  Goldberger  for  re- 
vising the  chapters  upon  Measles  and  Typhiis  Fever,  to  Prof.  George 
C.  Whipple  for  reading  and  improving  the  chapter  upon  Water,  to 
Charles  T.  Brues  for  many  suggestions  in  the  section  upon  insect-borne 
diseases,  and  to  Prof.  W.  E.  Castle  for  a  similar  service  with  the  section 
on  Heredity.  Dr.  Charles  Wardell  Stiles  has  kindly  furnished  infor- 
mation concerning  the  relation  of  parasites  to  soil.  I  also  desire  to 
express  my  obligations  to  Prof.  Arthur  I.  Kendall,  Dr.  Harold  L.  Amoss, 
Dr.  Lewis  W.  Hackett,  Prof.  William  D.  Frost,  and  Miss  Emily  G. 
Philpotts. 


PREFACE  TO  FIEST  EDITIOX  ix 

It  has  l)ceii  my  olgcct  to  give  in  this  volume  the  seieiitilic  basis 
upon  which  the  prevention  of  disease  and  the  maintenance  of  h«alth 
must  rest.  Exact  Ivnowledge  has  taken  the  place  of  fads  and  fancies 
in  hygiene  and  sanitation;  the  capable  health  olticer  now  possesses  facts 
concerning  infections  which  permit  their  prevention  and  even  their 
suppression  in  some  instances.  ^lany  of  these  problems  are  complicated 
with  economic  and  social  difficulties,  which  are  given  due  consideration, 
for  preventive  medicine  has  become  a  basic  factor  in  sociology. 

Boston.  M.  J.  Eose^^au. 


PREFACE   TO   THE   SECOND   EDITION 

The  rapid  increase  in  our  knowledge  has  called  for  a  resetting  of  this 
book.  I  have  taken  advantage  of  this  to  omit  some  paragraphs  and 
topics,  to  add  others,  and  to  remodel  the  remainder.  The  work,  m  fact, 
has  been  largely  rewritten. 

The  following  subjects  have  been  added :  Prevalence  of  Venereal 
Diseases,  Chancroid,  The  Schick  Eeaction,  The  Bang  Method  of  Sup- 
pressing Bovine  Tuberculosis,  Organization  of  a  Local  Tuberculosis 
Campaign,  Tuberculosis  Sanatoria  and  Dispensaries,  Emetine,  Insecti- 
cidal  Agents  Especially  for  Lice  and  Fleas,  Standardization  of  Bacterial 
Vaccines,  Sensitized  Vaccines,  Nuisances,  Eoaches,  Feeble-mindedness, 
The  Wassermann  Test,  Belation  between  Host  and  Parasite,  Essential 
Requirements  for  a  Safe  Milk  SupjDly,  Butter,  Desiccated  and  Con- 
densed Milk,  Streptococci  of  Sore  Throat,  Sodium  Fluorid,  Hydrofluoric 
Acid,  Cancer  Heredity,  Tests  for  Heated  Milk,  Echinococcus  Disease, 
Carbon  Dioxid  in  Alveolar  Air,  Sanitary  Significance  of  Odors,  Ocular 
Hygiene,  Hydrogen  Sulphid,  Methane,  Accidents  in  Sewers  and  Their 
Prevention,  Eeinspiration  of  Expired  Air,  Air  Washing  with  Eeference 
to  Ventilation,  Goiter,  Sanitation  of  Swimming  Pools,  Military  Hy- 
giene, Etc. 

The  following  chapters  have  been  rewritten  in  whole  or  in  part : 
Leprosy,  Mushroom  Poisoning,  Beriberi,  Pellagra,  Carbon  Monoxid, 
Chlorinated  Lime,  Vital  Statistics  (by  Trask),  Disinfection,  Quinin 
Prophylaxis  for  Malaria.  The  subject  treated  in  the  chapter  on  Pre- 
vention of  Mental  Diseases  in  the  first  edition  is  now  only  a  relatively 
small  part  of  the  field  of  mental  hygiene.  Therefore,  in  this  edition 
both  the  title  and  the  scope  of  this  chapter  have  been  changed  to 
Mental  Hygiene. 

An  entirely  new  section  on  Military  Hygiene  has  been  added. 

The  uniform  courtesies  of  the  publishers  have  been  appreciated  and 
I  also  thank  those  who  called  my  attention  to  mistakes  of  commission 
or  omission.     I  am  greatly  indebted  to  Dr.  J.  Penteado  Bill  for  much 

xi 


Xii  PRKF.\C!I<]  'IV)  ^rilK;  SK/'0\I)  I'^DITTOX 

assi.stiiiic(!  ill  preparing!;  lliis  cililioii;  also  lo  l)i'.  ('has.  !>.  Spniit,  Dr. 
AVilsoji  (I.  Smillie  and  Mi.ss  l\Iao  ('.  Moraii  for  aid  in  scciii^^  these  j)agcs 
tliroiigli  tlie  i^ross.  The  favorable  receptiou  which  the  book  lias  received 
is  gratifying. 

Boston.  M.  J.  Eosenau. 


CONTENTS 

SECTION  I 
PREVENTION    OF    THE    COMMUNICABLE   DISEASES 

CHAPTER  PAGE 

I.— Diseases  Having  Specific  or  Special  Prophylactic  Measures  1 
Smallpox  and  Vaccination  :  Historical  Note,  1 ;  Vaccination,  3 ; 
Vaccine  Virus,  4;  Methods  of  Vaccination,  9;  Indices  of  a  Suc- 
cessful Vaccination,  11;  The  Immunity,  13;  Revaceination,  18; 
Claims  for  Vaccination,  20 ;  Vaccination  of  Exposed  Persons,  20 ; 
Dangers  and  Complications,  21;  Government  Control  of  Vaccine 
Virus,  24;  Unity  of  Cowpox  and  Smallpox,  25;  Compulsory 
Vaccination,  25 ;  Inoculation  or  Variola  Inoculata,  27 ;  Prevalence 
of  Smallpox,  29;  Epidemiology,  30;  Modes  of  Infection,  30; 
Resistance  of  the  Virus,  31 ;  Smallpox  in  the  Vaccinated  and  Un- 
vaceinated,  33 ;  The  Result  of  Vaccination  in  Germany,  33 ;  Isola- 
tion and  Disinfection,  36. 

Rabies  :  General  Considerations,  39 ;  Period  of  Incubation,  40 ; 
Exit  and  Entrance  of  the  Virus,  41;  The  Relative  Danger  of 
Bites,  42;  Viability,  42;  Prophylaxis,  43;  The  Local  Treatment 
of  the  Wound,  44;  The  Pasteur  Prophylactic  Treatment,  45. 
Venereal  Diseases:  Syphilis,  54;  Gonorrhea,  58;  Chan- 
croid, 60. 

Venereal  Prophylaxis  and  Hygiene  op  Sex:  Prevalence,  61; 
Attitude,  62 ;  Education,  63 ;  Registration  of  Cases,  65 ;  Con- 
tinence, 65 ;  Personal  Hygiene,  66 ;  Alcohol,  66 ;  Prostitution,  66 ; 
Medical  Prophylaxis,  67;  Segregation,  68. 
Preventable  Blindness:  Trachoma,  69;  Wood  Alcohol,  70; 
Accidents,  70;  Ophthalmia  Neonatorum,  71;  Prevalence,  71; 
Prevention,  72;   Legislation,  74. 

Tetanus:     Etiology,  75;  Incubation,  79;   Resistance,  79;  Pro- 
phylaxis, 80. 

II. — Diseases  Spread  Largely  Through  the  Alvine  Discharges  83 
Typhoid  Fever:  General  Considerations,  83;  Pi-evalenee,  84; 
Channels  of  Entrance  and  Exit,  89;  Diagnosis,  89;  Bacillus 
Carriers,  92 ;  Resistance  of  the  Virus,  93 ;  Typhoid  Bacillus  in 
Nature,  94;  Modes  of  Spread,  94;  Preventive  Typhoid  Inocu- 
lations, 104;  Management  of  a  Case  so  as  to  Prevent  Spread, 
108;   Summary — Personal  Prophylaxis,  110. 


xiv  '        CONTENTS 

CHAPTER 

Cholera:  General  Considerations,  112;  The  Cause  and  Con- 
tributing' Causes  of  Cholera,  113;  Diag-nosis,  114;  Modes  of 
Transmission,  115;  Immunity  and  Prophylactic  Inoculations, 
118;  Quarantine,  119;  Personal  Prophylaxis,  120;  Summary — 
Prevention,  120. 

Dysentery:  Classification,  121;  Mode  of  Transmission,  122; 
Resistance,  123;  Immunity,  123;  Prophylaxis,  124. 

Hookworm  Disease:  Distribution,  125;  Varieties  of  Hook- 
worm, 126;  Modes  of  Transmission,  127;  The  Parasite,  127; 
Immunity,  130 ;  Resistance  of  the  Parasite,  130 ;  Prevention,  130 ; 
Collateral  Benefits,  132. 


III. — Diseases    Spread    Largely    Through    Discharges    from    the 

Mouth  and  Nose 134 

Tuberculosis  :  General  Considerations,  134 ;  The  Difference  be- 
tween Human  and  Bovine  Tubei'cle  Bacilli,  135;  Bovine  Tuber- 
culosis in  Man,  136 ;  Modes  of  Infection,  141 ;  Immunity,  147 ; 
Resistance  of  the  Virus,  150;  Prevention,  150;  Segregation, 
Sanatoria,  152;  Personal  Prophylaxis,  153;  Tuberculosis  in 
Children,  156;  Bovine  Tuberculosis,  157;  The  Bang  Method  of 
Suppressing  Bovine  Tuberculosis,  157;  Organizing  a  Local 
Tuberculosis   Campaign,  158;   Summary,  158. 

Diphtheria:  General  Considerations,  159;  Modes  of  Trans- 
mission, 160;  Bacillus  Carriers,  162;  Resistance,  165;  Immunity, 
165 ;  The  Schick  Reaction,  166 ;  Prevention,  166 ;  Personal  Pro- 
phylaxis, 169;  Prevention  of  Post-diphtheritic  Paralysis,  169; 
Prevention  of  Serum  Sickness,  170;  Historical  Note,  171. 

Measles:  General  Considerations,  172;  Immunity,  174;  Resist- 
ance of  the  Virus,  174;  Modes  of  Transmission,  175;  Prevention, 
176. 

Scarlet  Fever:  General  Considerations,  178;  Modes  of  Trans- 
mission, 179;  Immunity,  182;  Prophylaxis,  182. 

Whooping  Cough  :  Modes  of  Transmission,  184 ;  Immunity,  184 ; 
Prevention,  185 ;  Mortality,  186. 

Mumps,  187. 

Pneumonia:  General  Considerations,  188;  Modes  of  Trans- 
mission, 189;  Resistance  of  the  Virus,  189;  Immunity,  190; 
Prevention,   190. 

Influenza:  Immunity,  192;  Modes  of  Transmission,  193; 
Prophylaxis,  193. 

Common  Colds:  General  Considerations,  194;  Prevention,  195. 
Cerebrospinal  Fever:  General  Considerations,  197;  Preven- 
tion, 199. 


CONTENTS  XV 

:hapter  page 

IV. — Insect-Borne  Diseases        ........    201 

General  Considerations,  201. 

Insecticides:     Preparation  of  the  Room  for  Fumigation,  208; 
The  Relative  Efficiency  of  Insecticides,  209;  Sulphur,  211;  For-  " 
maldehyd,  212;  Pyrethrum,  213;  Phenol-camphor,  214;  Hydro- 
cyanic Acid  Gas,  215;  Bisulphid  of  Carbon,  216;  Petroleum,  217; 
Arsenic,  218. 

Mosquitoes  :  Life  History  and  Habits,  221 ;  The  Destruction  of 
Mosquitoes,  223;  Malaria,  228;  Yellow  Fever,  236;  Dengue,  244; 
Filariasis,  246. 

Flies:  General  Considerations,  247;  Life  History  of  Musca 
Domestica,  249 ;  Life  History  of  Stomoxys  Calcitrans,  250 ;  Flies 
as  Mechanical  Carriers  of  Infection,  250;  Suppression,  254; 
Sleeping  Sickness,  256;  Pappataci  Fever,  261. 
Fleas:  General  Considerations,  261;  Pulicides,  264;  Relation 
of  Plague  to  Rats  and  Fleas,  264. 

Rats  and  Other  Rodents:     General  Considerations,  267;  Breed- 
ing and  Prevalence,  268 ;  Migration,  269 ;  On  Ships,  270 ;  Food, 
270;  Habits,  270;  Rat-Bite  Fever,  271;  Plague  in  Rats,  271;  Rat 
Leprosy,  273;  Trichinosis,  273;  Other  Parasites,  273;  Economic 
Importance,  273 ;  Suppression,  274 ;  Squirrels,  279 ;  Plague,  281. 
Ticks:     General  Considerations,  287;  Texas  Fever,  288;  Rocky 
Mountain  Spotted  Fever,  289;  Relapsing  Fever,  292. 
Lice:     General  Considerations,  294;   Typhus  Fever,  295. 
Bedbugs:      General    Considerations,   299;    The    Suppression   of 
Bedbugs,  300;  Kala-Azar,  301. 
Roaches,  301. 
References,  303. 

V. — Miscellaneous  Diseases 304 

Infantile  Paralysis:     General  Considerations,  304;  Resistance 
of  the  Virus,  306 ;  Immunity,  306 ;  Modes  of  Transmission,  306 ; 
Prevention,  308. 
Chickenpox,  309, 

Glanders:     General  Considerations,  310;  Diagnosis,  311;  Pre- 
vention, 314. 
Anthrax:     Resistance,  316;  Immunity,  316;  Prevention,  316. 

FOOT-AND-MoUTH    DiSEASE,    317. 

Malta  Fever:     Modes  of  Transmission,  319;   Goats'  Milk  and 
Malta  Fever,  321;  Resistance,  322;  Prevention,   322. 
Leprosy:      General    Considerations,    322;    Immunity,    324;    Rat 
Leprosy,   325;    Modes   of   Transmission,    326;    Prevention,   329; 
Specific   Prevention,    330;    References,    330. 


xvi  CONTENTS 

CHAPTER  PAGE 

VI. — Mental  IIygjkne  (By  Tliomas  W.  Salmon,  M.lX)  .  .  .  331 
General  Considerations,  331 ;  Importance  of  the  Problems,  332 ; 
Heredity,  334;  Alcohol,  33S;  Other  Exogenous  Poisons,  342; 
•  Endogenous  Poisons,  342;  Syphilis,  342;  Other  Infections,  346; 
Head  Injuries,  347;  Mental  Causes,  352;  Economic  Factors, 
352;  Immigration,  353. 

Agencies  Available  for  the  Application  of  Preventive 
Measures:  Hospitals  for  Mental  Disease,  354;  Boards  of  Ad- 
ministration and  Supervision,  356;  Public  Health  Authorities, 
356;  Educational  .Authorities,  356;  National  and  Local  Societies 
for  Mental  Hygiene,  357. 
Conclusion,  358. 
References,  359. 

VII. — Some  General  Considerations .    362 

Sources  of  Infection,  362;  Modes  of  Transference,  363;  Carriers, 
364;  Missed  Cases,  365;  Channels  of  Infection,  366;  "Con- 
tagious" and  "Infectious,"  366;  Epidemic,  Endemic,  Pandemic, 
and  Prosodemic,  367 ;  Fomites,  368 ;  The  Management  of  an  Epi- 
demic Campaign,  368. 

Quarantine  :       Maritime    Quarantine,     372 ;     Quarantine    Pro- 
cedures, 376;    The   Bill   of  Health,   377;   The   Equipment   of   a 
Quarantine     Station,     377;     Qualifications     of    the     Quarantine 
Officer,   378;   Disinfection   of   Ships,   378;   Cargo,  382;   Ballast, 
382;    Foreig-n    Inspection    Service,    382;    National   versus    State 
Quarantine,  383;  Interstate  Quarantine,  383. 
Isolation,  384. 
Nuisances,  386. 
References,  387. 


SECTION    II 
IMMUNITY,    HEREDITY   AND    EUGENICS 

I. — Immunity       .        . 389 

General  Considerations,  389 ;  Mechanism  and  Theories  of  Immu- 
nity, 390 ;  Natural  Immunity,  393 ;  Acquired  Immunity,  394 ; 
Mixed  Immunity,  395;  Hoav  Active  Immunity  May  Be  Acquired, 
395 ;  Standardization  of  Bacterial  Vaccines,  398 ;  Specificity,  398 ; 
Local  and  General  Immunity,  400;  Bacillus  Carriers  or  Immu- 
nitas  Non  Sterilans,  401 ;  Latency,  403 ;  Lowered  Resistance,  403 ; 
Relation  between  Host  and  Parasite,  407;  Ehrlieh's  Side-Chain 
Theory  of  Immunity,  408;  Antitoxic  Immunity,  413. 
Toxins,  414. 


CONTEI^TS  xvii 

CHAPTER  PAGE 

Antitoxins:     General  Considerations,  418;  Gibson's  Method  of 
Concentrating  Diphtiieria  Antitoxin,  423;  Dried  Antitoxin,  424; 
Mode  of  Action,  424. 
Endotoxins,  425. 

Tetanus  Toxin  :  General  Considerations,  426 ;  Mode  of  Action, 
429. 

Tetanus  Antitoxin,  430. 

Standardization  of  Antitoxic  Sera:     The  Standardization  of 
Diphtheria   Antitoxin,    431;    Standardization    of   Tetanus   Anti- 
toxin, 433, 
Phagocttosis,  436. 
Opsonins:     The  Opsonic  Index,  440. 
Lysins:     Pfeiffer's  Phenomenon,  441. 
Hemolysis,  443. 
Cytotoxins,  445. 

The  Bordet-Gengou  Phenomenon — Fixation  of  Complement  : 
The  Wasserman  Reaction,  446. 

The  Neisser-Wechsberg  Phenomenon  or  Deviation  of  the 
Complement,  449. 

Precipitins  :  General  Considerations,  450 ;  Tests  for  Blood,  452. 
Agglutinins,  454. 

Anaphylaxis  :  General  Considerations,  457 ;  Examples  of  Ana- 
phylaxis, 458 ;  Experimental  Serum  Anaphylaxis,  458 ;  Speci- 
ficity, 460;  Sensitization  by  Feeding,  462;  Maternal  Transmis- 
sion, 462;  Serum  Anaphylaxis  in  Man,  or  Serum  Sickness,  462; 
Hypersusceptibility  and  Immunity  Produced  by  Bacterial  Pro- 
teins, 465 ;  Relation  of  Anaphylaxis  to  Protein  Metabolism,  465 ; 
Relation  of  Anaphylaxis  to  Endotoxins,  466;  The  Relation  of 
Anaphylaxis  to  Tuberculosis,  466 ;  Relation  of  Anaphylaxis  to 
Vaccination,  467;  Relation  of  Anaphylaxis  to  Hay  Fever,  468; 
Other  Practical  Relations  of  Anaphylaxis,  468. 
References,  469. 

II. — Heredity  and  Eugenics 470 

General  Considerations,  470;  Feeble-minded  Idiots,  Imbeciles  and 
Morons,  471;  Prevention  of  Propagation  of  Defectives,  472; 
Statistics  of  Defectives,  474;  Degenerate  Families,  476. 

Eugenics,  479. 

Principles  of  Heredity:  Variation,  481;  Darwin's  Theory, 
482;  Mutation,  483;  De  Vries — Discontinuous  Evolution,  483; 
Weismann's  Views,  484;  Mendel's  Law,  485;  Atavism  or  Rever- 
sion, 488;  Gallon's  Law  of  Filial  Regression,  490. 

The  Cell  in  Heredity,  490. 
Biometry,  492. 


xviii  CONTENTS 

CHAPTER  PACK 

Heredity  Versus  Environment,  490. 
Immunity  Gained  Through  Inheritance,  497. 

III. — The  Hereditary  Transmission  of  Disease  ....  498 
General  Considerations,  498;  The  Microbie  Diseases,  500; 
Hereditary  Transmission  of  a  Tendency  to  a  Disease,  501 ;  Tuber- 
culosis, 502;  Syphilis,  502;  The  Wassermann  Reaction,  503; 
Cancer,  504;  Deaf -Mutism,  505;  Albinism,  506;  Color-blindness, 
or  Daltonism,  507;  Hemophilia,  508;  Gout,  508;  Braehydactylism, 
508;  Polydactylism,  509;  Myopia,  509;  Cataract,  509;  Retinitis 
Pigmentosa,  509 ;  Diabetes  Mellitus,  509 ;  Orthostatic  Albumin- 
uria, 509;  Alcoholism,  510;  Epilepsy,  511;  Huntington's  Chorea, 
512 ;  Friedreich's  Disease — Hereditary  Ataxia,  513 ;  Insanity,  514. 
References,  515. 

SECTION   III 
FOODS 

I. — General  Considerations 516 

The  Uses  op  Food,  518. 

Classification  of  Foods:     Physical  Properties,  519;   Sources, 
519;  Composition  and  Function,  520;  Classification,  520. 
The  Amount  of  Food  :     Excessive  Amounts,  521 ;  Insufficient 
Food,  521;  Unbalanced  Diets,  522;  Salts  in  the  Diet,  523. 
Adulteration  of  Food,  523. 

Decomposed  Foods  :  Fermentation  and  Putrefaction,  527 ; 
"Ptomain"  Poisoning,  528. 

Preservation  op  Foods:  Cold,  533;  Drying,  536;  Salting  and 
Pickling,  538;  Jellies  and  Preserves,  539;  Smoking,  539;  Chem- 
ical Preservatives,  542. 

The  Preparation  of  Food  :  Cooking,  550 ;  Methods  of  Cooking, 
552. 

II. — Animal  Foods:    Milk 553 

Milk  :  General  Considerations,  553 ;  Composition,  554 ;  Milk 
Standards,  558;  Ferments  or  "Life"  in  Milk,  559;  "Leukocytes" 
in  Milk,  561 ;  The  Excretion  of  Drugs  in  Milk,  562 ;  The  Differ- 
ences between  Cow's  Milk  and  Woman's  Milk,  562;  Classifieation 
of  Milk,  563;  The  Decomposition  of  Milk,  565;  Bitter  Milk,  567; 
Colored  Milk,  568 ;  Adulterations  of  Milk,  568 ;  Dirty  Milk— The 
Dirt  Test,  568;  Bacteria  in  Milk,  569;  The  Germicidal  Property 
of  Milk,  571;  Diseases  Spread  by  Milk,  571;  The  Character  of 
Milk-borne  Epidemics,  578;  Desiccated  Milk,  579;  Condensed 
Milk,  579;  Fresh  Milk  Products,  579;  Butter,  580;  Inspection, 
582;  Pasteurization,  582;  The  Effect  of  Heat  upon  Milk,  586. 


CONTENTS  xix 

CHAPTER  PAGE 

The  Bacteriological  Examijstation  of  Milk  :     The  Number  of 

Bacteria,  588;  The  Kinds  of  Bacteria,  589. 

Microscopic  Examination:     The   Stewart-Slack  Method,  591; 

The   Doane-Buckley  Method,  591;   The   Prescott-Breed  Method, 

591. 

Chemical  Analysis  of  Milk  :    Total  Solids,  592 ;  Determination 

of  Total  Solids,  592 ;  Determination  of  Fats,  593 ;  Determination 

of  Milk  Sugar,  596;  Determination  of  Proteins,  597;  Water,  598; 

Reaction,  599;  Specific  Gravity,  600;  Heated  Milk,  601. 

References,  603. 

III. — Animal  Foods  :  Meat,  Fish,  Eggs,  Etc 605 

Meat:  Structure  and  Composition  of  Meats,  605;  Nutritive 
Value  of  Meat,  606;  Sources  of  Meat,  607;  The  Recognition  of 
Spoiled  Meat,  608;  Prevention,  608;  Meat  Preservatives,  608. 
Meat  Inspection  :  General  Considerations,  609 ;  The  Abattoir, 
610;  Qualifications  of  a  Meat  Inspectoi',  612;  The  Freibank  or 
Three-class  Meat  System,  612;  Emergency  Slaughter,  613; 
Methods  of  Slaughter,  613;  The  United  States  Meat  Inspection 
Law,  614 ;  Ante-mortem  Inspection,  615 ;  Post-mortem  Inspection, 
615. 

Meat  Poisoning:  General  Considerations,  618;  Paratyphoid 
Fever,  623;  Botulism  or  Sausage  Poisoning,  626;  Animal  Para- 
sites, 629. 

Fish:  Physiological  Fish  Poisoning,  635;  Bacterial  Poisons, 
635;  The  Fish  Tajieworm,  635. 

Shellfish  :  General  Considerations,  636 ;  Mussel  Poisoning, 
639;  Miscellaneous,  640. 

Bob  Veal,  640. 
Eggs,  641. 

IV.— Plant   Foods „        ...    644 

Poisoning  from  Plant  Foods  :  Ei-gotism,  644 ;  Lathyrism,  645 ; 
Mushroom  Poisoning,  645;  Potato  Poisoning,  648;  Beriberi,  649; 
Pellagi^a,    653. 

References,  659. 

SECTION   IV 
AIR 

I. — Composition  op  the  Air 661 

General  Considerations,  661 ;  Oxygen,  663 ;  Nitrogen,  655 ;  Argon, 
655;  Ozone,  655;  Hydrogen  Peroxid,  667;  Ammonia,  667;  Min- 
eral Acids,  668;  The  Amount  and  Function  of  COg  in  Alveolar 


XX  CONTIvXTS 

CHAPTER  PAGE 

Ail-,  (if)!);  ('()„  MS  an  Index  of  Vitiation,  (i71;  Methods  for  Deter- 
mining' Carbon  Dioxid,  (572 

II. — Pressure,  Temperature  and  Humidity 681 

Pressure:      Normal    Atmospheric    Pressure,    681;     Diminished 
Atmospheric    Pressure,    681 ;    Increased    Atmospheric    Pressure, 
683;  Barometers,  684. 
Movements  of  the  Atmosphere,  685. 

Temperature  of  the  Air:  General  Considerations,  687;  Meth- 
ods of  Recording  Temperature,  688. 

Humidity:  Aqueous  Vapor,  689;  Methods  of  Detennining 
Humidity  in  Air,  693;  Relation  of  Humidity  and  Temperature 
to  Health,  697;  Effects  of  Wann  Moist  Air,  700;  Effects  of  Cold 
Damp  Air,  700;   Effects  of  Warm  Dry  Air,  701, 

III. — Miscellaneous 703 

Odors,   703;    Light,    705;    Electricity,    707;    Radioactivity,   708; 
.  Smoke,  708;  Fog,  711;  Dust,  712;  Dust  and  Disease,  713;  Meth- 
ods for  Examining  Dust,  715. 

IV. — Bacteria  and  Poisonous  Gases  in  the  Air      ....    716 
Bacteria  in  the  Air  :     General  Considerations,  716 ;  Methods 
for  Determining  Bacteria  in  the  Air,  717;   Air  and  Infection, 
719. 

Poisonous  Gases  in  the  Air:     Carbon  Monoxid,  721;  Illumi- 
nating Gas,  723;   Other  Gases  in  the  Air,  726. 
Sewer  Gas  :     Bacteria  in  Sewer  Aii',  729 ;  Accidents  in  Sewers, 
730;  Illustrative  Cases  of  Death  Attributed  to  Sewer  Gas,  731; 
Prevention  of  Accidents  in  Sewers,  733;  Ventilation  of  Sewers,  ' 
733. 

V. — Fresh  and  Vitiated  Air 735 

The  Benefits  of  Fresh  Air,  735. 

The  Effects  of  Vitiated  Air:     General  Considerations,  735; 

The  Effects  of  Increased  Carbon  Dioxid  and  Diminished  Oxygen, 

737 ;  PoisoHS  in  the  Expired  Breath,  738 ;  Physical  Changes  in  the 

Air,  740;  Reinspiration  of  Expired  Air,  742. 

Summary,  744. 

VI. — Ventilation  and  Heating 746 

Ventilation  :  General  Considerations,  746 ;  Air  Washing,  748 ; 
Recirculation,  748;  Vitiation  by  Respiration,  749;  Dead-Space 
Air,  750;  Factor  of  Safety,  750;  The  Amount  of  Air  Required, 
750;  Standards  of  Purity  and  Efficiency  of  Ventilation,  753; 
The  Size  and  Shape  of  the  Room,  754;  Inlets  and  Outlets,  756; 


CONTENTS  xxi 

CHAPTER  PAGE 

External  Ventilation,  758;  Natural  Ventilation,  758;  Mechanical 

Ventilation,  762. 

Heating:       General    Considerations,    762;     Open    Fires,    763; 

Franklin  Stoves,  764 ;  Open  Gas  Heaters,  764 ;  Hot-air  Furnaces, 

764;   Hot-water  and   Steam  Pipes,  765;   Electric  Heating,  765; 

The  Cooling-  of  Rooms,  765. 

References,  765. 

SECTION   V 

SOIL 

I. — General  Considerations 767 

Classification  of  Soils,  768;  Surface  Configuration,  768;  Com- 
position of  the  Soil,  769;  Physical  Properties,  770;  Soil  Air,  771; 
Soil  Water,  772;  The  Nitrogen   Cycle,  773;  The  Carbon  Cycle, 

777. 

II. — Soil  and  Its  Relation  to  Disease 778 

Bacteria  in  Soil,  778;  Pollution  of  the  Soil,  779;  Dirt,  780; 
Cleanliness,  781;  The  Influence  of  the  Soil  upon  Health,  782; 
Diseases  Associated  with  the  Soil,  782. 


SECTION   VI 
WATER 

I. — General  Considerations 789 

Composition,  789;    Classification  of  Water,   790;   Pi'operties  of 
Water,  791 ;  The  Uses  of  Water  in  the  Body,  791 ;  The  Amount 
of  Water  Used  and  Wasted,  792 ;  Double  Water  Supplies,  79 
Sources  of  Water:     Rain  Water,  797;   Surface  Waters,  800; 
Ground  Water,  806. 

Sources  and  Nature  of  Water  Pollution  and  Infection: 
General  Considerations,  816;  Simple  Tests  to  Determine  Nature 
of  Pollution,  817;  The  Interstate  Pollution  of  Streams,  818; 
The  Care,  of  Catchment  Areas,  819. 

II. — Sanitary  Analysis  of  Water      . 821 

Standard  Methods,  821. 

Odors   and   Taste:      General   Considerations,   823;    Method   of 

Determining  Odor,  826;  Prevention  and  Removal  of  Tastes  and 

Odors,  827. 

Color:      General   Considerations,   828;   Method  for    Estimating 

Color,  829. 


xxii  CONTENTS 

CHAPTER  PAGE 

Turbidity:     General  Considerations,  829;  Methods  for  Estimat- 
ing Turbidity,  831. 
Reaction,  831. 
Total  Solids:    Method,  833. 

Hardness:     General  Considerations,  834;  Methods,  836. 
Organic  Matter:     Free  Ammonia,  837;  Albuminoid  Ammonia, 
841;  Nitrites,  842;  Nitrates,  844. 

Chlorin:  General  Considerations,  840;  Determination  of 
Chlorin,  847. 

Oxygen:     Oxygen  Consumed,  848;  Dissolved  Oxygen,  850. 
Iron:     General  Considerations,  852;  Iron  Pipes,  852, 
Lead  :     Tests,  853. 
Expression  of  Chemical  Results,  854. 

III. — Microscopical  Examination  op  Water      .        .        .        .        .    855 
The  Sedgwick-Rafter  Method,  855;  Significance  of  the  examina- 
tion, 857. 

Bacteriological  Examination:  The  Number  of  Bacteria  in 
Water,  858;  Method  for  Determining  the  Number  of  Bacteria  in 
Water,  860;  Kinds  of  Bacteria  in  Water,  861. 

IV, — Interpretation  of  Sanitary  Water  Analysis   ....    866 
General  Considerations,  866;  Allowable  Limits,  867;  Illustrative 
Analyses  Interpreted,  869. 

V. — The  Purification  of  Water 878 

Nature's  Method  of  Purifying  Water:  General  Considera- 
tions, 878 ;  Evaporation  and  Condensation,  879 ;  Self -purification 
of  Streams,  879;   Storage  in  Lakes  and  Ponds,  881. 

Distilled  Water,  882. 

Boiled  Water,  882. 

Filters:      Slow    Sand   Filters,   883;    Mechanical   Filters,   890; 

Household   Filters,   894;    Scrubbing  or  Roug-hing  Filters,   895; 

Screening,  895. 

Storage,  896. 

Sedimentation,  896, 

Chemical  Methods  of  Purifying  Water:  Ozone,  897;  Chlori- 
nated Lime — Bleaching  Powder  or  "Chlorid  of  Lime,"  900; 
Chlorin,  905;  Permanganate  of  Potash,  906;  Alum  or  Sulphate 
of  Aluminum,  906;  Sulphate  of  Iron  and  Lime,  908;  Metallic 
Iron:   The  Anderson  Process,  909;   Copper  Sulphate,  909. 

Ultraviolet  Rays,  910. 


CONTENTS  xxiii 

ClJAPTEIt  ■  PAGE 

VI. — Water  and  Its  Relation  to  Disease  ......    912 

General  Considerations,  912. 
The  Mills-Reincke  Phenomenon,  913. 

Non-Specific   Diseases  Due  to  Water:     General   Considera- 
tions, 915;   Goiter,  916;   Lead  Poisoning,  920. 
Specific   Diseases   Due   to   Water:      General    Considerations, 
923;  Cholera,  925;  Typhoid  Tever,  932;  Dysentery,  944;  Diar- 
rhea, 945;  Animal  Parasites,  946. 
The  Sanitation  of  Swimming  Pools,  947. 
Ice:      General    Considerations,   947;    Natnral   Ice,    950;    Manu- 
factured Ice,  950;  Ice  and  Disease,  952. 
References,  953. 

SECTION   VII 

SEWAGE   DISPOSAL 

By  George  C.  Whipple 

General  Considerations:  Importance  of  Speedy  Removal  of 
Fecal  Matter,  955;  Dry  Earth  System,  956;  Water  Carriage 
System,  956;  Separate  atid  Combined  Systems,  957;  Quantity 
of  Sewage,  958;  Composition  of  Sewage,  958;  Ventilation  and 
Flushing  of  Sewers,  960. 

Stream  Pollution  :  Sewage  Disposal  by  Dilution,  960 ;  Hygienic 
Aspects  of  Stream  Pollution,  962;  Protection  against  Pollution, 
963 ;  Fundamental  Principles  of  Sewage  Treatment,  964 ;  Prepar- 
atory   Processes,    964;    Purification    Processes,    966;    Finishing 
Processes,  971;  Choice  of  Methods,  972;  Relative  Bacterial  Effi- 
ciency of  Different  Processes,  972 ;  Management  of  Sewage  Treat- 
ment Works,  973 ;  Treatment  Plants  as  Nuisances,  973 ;  Nuisances 
Caused  by  Trade  Wastes,  974. 
Cooperative  Sanitation,  976. 
The  Rural  Problem  of  Sewage  Disposal,  976. 
References,,  979. 

SECTION   VIII 

REFUSE    DISPOSAL 

By  George  C.  Whipple 

General  Considerations,  981;  Incineration  Plants,  984;  Reduction 
Plants,  985;  Feeding  Garbage  to  Hogs,  986;  Collection  of  Gar- 
bage, 986;  References,  986. 


xxiv  ('0\"IM<:X'l\S 

CHAI'TIOK 

SECTION    IX 

VITAL    STATISTICS 

By  John  W.  Tha.sk,  M.  D. 

General  Considerations,  987. 

Vital   Statistics:     Definition,   flS.S;   Development,  9S<S;   Based 

upon  Population,  989. 

Population  Statistics:  Source  of  Data,  989;  Nature  of  Census 
Information,  990;  Sources  of  EiTor  in  Census  Enumerations, 
990;  riuctuation  in  Population,  991;  Estimates  of  Population, 
991. 

Marriage  Statistics  :  Man-iage  Rates,  994 ;  Factors  Influencing 
Mariiage  Rates,  994;  Uses  of  Marriage  Registration,  995. 
Birth  Statistics:  General  Considerations,  995;  Registration  in 
the  United  States,  996;  Birth  Rates,  998;  Sources  of  Error  in 
Birth  Statistics,  999;  Uses  of  Birth  Registration  and  Statistics, 
999;  Factors  Influencing  Birth  Statistics,  1001. 
Morbidity  Statistics  :  General  Considerations,  1001 ;  Morbidity 
Statistics  in  the  United  States,  1003;  The  Notifiable  Diseases, 
1004;  The  Model  State  Law  for  Morbidity  Reports,  1005;  The 
Results  of  Notification  in  Certain  States  and  Cities,  1007;  Source 
of  Statistical  Data,  1007 ;  Nature  of  Information  Secured  by  Mor- 
bidity Notification,  1010 ;  The  Standard  Notification  Blank,  1012 ; 
Sources  of  Error  in  Morbidity  Statistics,  1013;  Uses  of  Mor- 
bidity Reports  and  Statistics,  1013;  Morbidity  Rates,  1014; 
Factors  Influencing  Morbidity  Rates,  1015;  Notification  of  Occu- 
pational Diseases,  1016. 

Mortality  Statistics  :     General  Considerations,  1017 ;  Registra- 
tion of  Deaths  in  the  United  States,  1018;  United  States  Regis- 
tration Area  for  Deaths,  1018 ;  Source  of  Data,  1019 ;  The  Stand- 
ard Death   Certificate,  1019 ;    Sources  of  Error,   1020 ;   Uses  of 
Death  Registration,  1023;  Death  Rates,  1024;  Factors  Affecting 
Death  Rates,  1026. 
Infant  Mortality,  1031. 
Life  Tables,  1032. 
References,  1033. 

SECTION    X 
INDUSTRIAL  HYGIENE  AND  DISEASES  OF  OCCUPATION 

General  Considerations,  1035. 

Some  Fundamental  Considerations  in  Prevention:  General 
Considerations,    1039;    Hours    of   Work,    1039;    Fatigue,   1040; 


COXTENTS  XXV 

HAPTEE  PAGF 

Minors,  1040 ;  Women,  1042 ;  Factory  Inspection,  1044 ;  Prevent- 
able Accidents,  1044;  Sedentary  Occupations,  1046. 
Diseases  op  Occupation:  Classification  of  the  Occupational 
Diseases,  1046;  Lead,  1047;  Phosphorus,  105G;  Arsenic,  1000; 
Mercury,  1061;  Carbon  Monoxid,  1063;  Hydrogen  Sulphid,  1064; 
Dusty  Trades,  1005;  The  Textile  Industries,  1068;  Wood  Dust, 
1070;  Mining,  1070;  Effects  of  Heat,  1072;  Communicable  In- 
fections, 1072;  Caisson  Disease,  1074. 

Eeperences,  1075. 

SECTION    XI 

SCHOOLS 

General  Consideiations,  1077;  School  P>uilding,  1079;  The  School- 
room, 1080 ;  The  School  Furniture,  1081 ;  Posture,  1085 ;  Lighting, 
1085 ;  Ventilation  and  Heating,  1086 ;  Water-closets  and  Urinals, 
1088 ;  Cloak-rooms,  1088 ;  Cleanliness,  1088 ;  Medical  Inspection  of 
Schools,  1089;  The  Communicable  Diseases  of  Childhood,  1092; 
Closing  Schools  on  Account  of  Epidemics,  1092;  The  Eyes;  The 
Ears;  The  Teeth;  Nose  and  Throat,  1094;  Diseases  of  the  Skin, 
1095;  Nervous  Diseases  and  Mental  Defects,  1096;  Vaccination, 
1097 ;  References,  1097. 

SECTION   XII 
DISINFECTION 

I. — General  Considerations 1099 

Disinfection,  1099;  Nature's  Disinfecting  Agents,  1101;  Clean- 
liness, 1101 ;  Antibiosis  and  Symbiosis,  1102 ;  When  and  Where 
to  Disinfect,  1102;  Qualifications  of  the  Disinfector,  1103;  Con- 
trols, 1103;  Disinfection  Must  P)e  in  Excess  of  Requirements, 
1103;  The  Ideal  Disinfectant,  1104;  Terminal  Disinfection,  1104; 
Penetration,  1105;  Albuminous  Matter,  1105;  Time,  1106;  Tem- 
perature, 1106 ;  Emulsions  and  Solutions,  1107 ;  Dilution,  1107 ; 
Reaction,  1108 ;  How  the  Bacteria  are  Killed,  1108 ;  The  Choice  of 
Germicide,  1108. 

The  Standardization  of  Disinfectant:  General  Considera- 
tions, 1109;  Methods  of  Standardizing  Disinfectants,  1110;  Car- 
bolic Coefficient,  1111. 

II. — Physical  Agents  of.  Disinfection 1119 

Sunlight,  1119;  Ultraviolet  Rays,  1119;  Electricity,  1121;  Burn- 
ing, 1121;  Dry  Heat,  1121;  Boiling,  1122;  Steam,  1122. 


xxvi  CONTENTS 

CHAPTKB  PAGE 

III. — Chemical  Agents  of  Disinfioction 1132 

Gaseous  Disinkkctants — Fumioation  :  Pi'cpai'nlion  nl'  \\u; 
Room,  1132;  rormaldeliyd  Gas,  IVS.i;  Sulphur  Dioxid,  ll'.iH; 
Hydrocyanic  Acid  Gas,  1144;  Chlorin,  1144;  Oxygen,  1146; 
Ozone,  114G. 

Liquid  Disinfectants  :     General  Considerations,  1146 ;  Methods 
of  Using  Chemical  Solutions,  1147 ;  Bichlorid  of  Mercury,  1147 ; 
Coal  Tar  Creosote,  1149;  Carbolic  Acid,  1150;  Phenol,  1151;  The 
Cresols,  1152;  Lysol,  1153;  Creolin,  1153;  Aseptol,  1153;  Asaprol, 
1153;  Sanatal,  1153;  Solveol  and  Solutol,  1154;  Naphthols,  1154; 
Naphthalene,   1154;   Formalin,   1154;   Potassium  Permanganate, 
1155;  Lime,  1156;  Antiformin,  1160;  Bromin  and  lodin,  1161; 
Ferrous  Sulphate,  1161;  Sulphate  of  Copper,  1161;  Chlorid  of 
Zinc,   1161. 
Acids,  1161. 
Alcohol,  1162. 
Soaps,  1162. 

Convenient  Formulae  for  Disinfecting  Solutions  :  Bichlorid 
of  Mercury,  or  Corrosive  Sublimate,  1164;  Formalin,  1164;  Milk 
of  Lime,  1164;  Carbolic  Acid,  1164;  Chlorinated  Lime,  1165. 

IV- — Methods  of  Disinfection 1166 

Air,  1166;  Rooms,  1166;  Stables,  1168;  Railroad  Cars,  1169; 
Feces,  1171;  Sputum,  1173;  Bed  and  Body  Linen,  1174;  Books, 
1174;  Cadavers,  1175;  Thermometers,  1176;  Wells  and  Cisterns, 
1176. 


SECTION    XIII 
MILITARY    HYGIENE 


General   Considerations 1177 

Recruits  and  Recruiting  :  General  Considerations,  1178 ;  Age, 
1179;  Character  and  Mental  Condition,  1180;  Height,  Weight 
and  Chest  Measurements,  1180 ;  Records,  1181 ;  Vaccination, 
1181;  General,  1181. 

Diseases  of  the  Soldier  :    General  Considerations,  1182. 
Organization  of  the  Medical  Department  :    General  Consid- 
erations, 1183;  Duties,  1186. 

Rations:  General  Considerations,  1189;  Garrison  Ration,  1189; 
Reserve  Ration,  1191;  Haversack  Ration,  1191;  Travel  Ration, 
1191;  Filipino  Scout  Ration,  1192;  French  Ration,  1192;  Emer- 
gency Ration,  1193;  German  Iron  Ration,  1193;  Japanese  Iron 
Ration,  1193. 


CONTENTS  xxvii 

HAPTER  PAGE 

Sanitation  in  Camp  and  on  the  March 1193 

Personal  Hygiene  of  the  Soldier,  1194;  Tlie  March,  1194;  Dis- 
cipline and  Sanitation,  1195. 

Equipment:     General    Considerations,    1197;    First-aid    Packet, 
1199;   Clothing,  1199. 

Physical  Training,  1203. 

Sanitation  of  Barracks  and  Permanent  Camps,  1203. 
Sanitation  of  Trenches,  1204. 

Drinking  Water,  1205;  Boiling,  1205;  Distillation,  1206;  Fil- 
tration, 1206;    Chemical   Disinfection,  1206. 
Disposal  op  Excreta,  1207;  Latrines,  1207. 
Disposal  of  Garbage,  1207. 
References,  1208. 

Index 1211 


LIST  OF  ILLIJSTEATIONS 


FIGURE 

1.  Vaccination  scars     ......... 

2.  Tiie  course  of  the  eruption       ....... 

3.  Vaccinia:  course  of  the  eruption  from  the  fourth  to  the  ninth  day 

4.  Vaccinia:  course  of  the  eruption  from  the  tenth  day  . 

5.  Smallpox  in  Liverpool  during  ten  years  (1902  to  1911) 

6.  Course  of  vaccination  and  revaccination    ..... 

7.  Smallpox  mortality  per  100,000  of  population  in  Breslau    . 

8.  Smallpox  mortality  per  100,000  of  population  in  Vienna   . 

9.  Smallpox  mortality  per  100,000  of  population  in  Prussia    . 

10.  Smallpox  mortality  per  100,000  of  population  in  Austria   . 

11.  Chart  showing  relation  of  enforcement  of  muzzling  law  to  prevalence 

of  rabies  in  Great  Britain         ...... 

12.  Influence  of  public  water  supplies  on  the  typhoid  fever  death  rate 

13.  Immediate   and   striking  effect  of   purifying   a   badly   infected   water 

supply  upon  the  typhoid   situation    . 

14.  Abrupt  reduction  in  death  rates  from  typhoid  fever  incident  to  water 

jjurification  in  four  American  cities  .... 

15.  Hookworm,  natural  size   ....... 

16.  Hookworm  embryo  ........ 

17.  Chart  showing  the  decline  in  the  death  rate  from  tuberculosis 

18.  Chart  computed  from  U.  S.  Census  Eeport  to  show  how  the  opening 

of  schools  in  autumn  increases  diphtheria  . 

19.  A  South  African  blood-sucking  fly   (Pangonia),  illustrating  long  pro 

boscis  to  pierce  heavy  fur  of  certain  animals 

20.  Example  of  sealing  doors  for  purpose  of  fumigation 

21.  Anopheles  punctipennis    ...... 

22.  Stegomyia  calopus   (female)      ..... 

23.  Head  of  stegomyia  calopus  (male)    .... 

24.  Eggs  of  stegomyia  calopus       ..... 

25.  Larva  of  stegomyia  calopus.    Kespiratory  syphon  of  culcx  to  the  right 

26.  Pupa  of  stegomyia  calopus       ..... 

27.  House  fly  showing  proboscis  in  the  act  of  eating  sugar 

28.  Eggs  of  house  fly  as  laid  in  a  mass  .... 

29.  Eggs  of  house  fly  .....  • 

30.  Larvae  of  house  fly  .....  ■ 

31.  Puparium  of  house  fly      .....  . 

32.  Stable  fly 


PAGE 
11 

12 
14 
15 
16 
19 
84 
35 
37 
38 

43 
95 

97 

98 
127 
127 
151 

160 

203 
209 
230 
238 
239 
240 
240 
241 
247 
248 
248 
249 
250 
250 


XXX 

FIGURE 

33. 

34. 
3.5. 
36. 
37. 
38. 
39. 
40. 


LIST  OF  lLLi:STKAT10NS 


49. 

50. 

51. 

52. 

53. 

54. 
55. 

56. 

57. 

58. 

59. 
60. 
61. 
62. 
63. 

64. 

65. 
66. 
67. 


Head  showing  proboscis,  stonioxys  calcitrans 

Wing  of  stable  fly  . 

The  "little  house  fly"     . 

Wing  of  house  fly  showing  liow  it  carries  dust  particles 

The  Hodge  fly  trap  on  a   garbage  can 

Tsetse  fly 

Various    gnats  .... 

The  Indian  rat  flea  .... 

41.  The  common  rat  flea  of  Europe  and  North  America 

42.  The  human  flea        .... 
A  squirrel  flea         .... 

General  scheme  for  testing  plague  rat  infection,  City  of  Manila  . 
Isolated  plague-infested  center,  Manila,  P.  I.   . 
The  Texas  fever  tick        ......... 

47.  Eocky  Mountain  spotted  fever  tick  ....... 

48.  The  bedbug 

Diagrammatic  representation  of  complement  fixation 

The  cell  with  its  various  combining  groups  or  side  chains  known  as 

receptors  .......... 

The  toxin  molecule:   showing  the  haptophore   (combining)   group,  and 
the  toxophore   (poison)   group   ....... 

The  first  stage  of  antitoxin  formation :  a  toxin  molecule  anchored  to  a 
receptor   ........... 

The    second    stage :    continued    stimulation    causes   a    reproduction    of 

receptors  .......... 

Third  stage:  the  receptors  beginning  to  leave  the  cell 

Fourth  stage:   the  receptors  have  left  the  cell  and  float  free  in  the 

blood-antitoxin  ......... 

The  neutralization  of  a  toxin  by  antitoxin;   the  free  receptors  in  the 

blood  have  united  with   the  toxin-antitoxic   immunity 
The  second  order  of  immunity,  showing  complement  and  immune  body 
The  third  order  of  immunity,   showing  an  immune  body  having  two 

affinities  ......... 

Diagram   illustrating   deviation    of    complement 

History  of  the  family  zero        ....... 

History  (condensed  and  incomplete)  of  three  markedly  able  families 

Wilson's  theory  of  inheritance  modified  by  Lock 

Diagram  showing  the  course  of  color  heredity  in  the  Andalusian  fowl, 

in  which  one  color  does  not  completely  dominate  another 
Diagram  showing  the  course   of  color  heredity  in   the  guinea-pig,  in 

which  one  color  (black)  completely  predominates  another  (w^hite) 

Model  to  illustrate  the  law  of  probability  or  ' '  chance "   . 

Normal    curve  ..........' 

Family  history  showing  deaf-mutism  ...... 


PAGE 
251 

251 
252 
253 
255 
257 
259 
262 
262 
263 
265 
285 
286 
289 
290 
299 
314 

410 

410 

411 

411 

411 

412 

412 
413 

413 
450 

477 
480 

484 

487 

487 
493 
494 
506 


LIST  OF  ILLUSTRATIONS  xxxi 

FIGUBE  PAGE 

68.  Family  history   showing  polydactylism 

69.  Family  history  showing  Huntington's  chorea 

70.  Family   history   showing   feeblemindedness 

71.  Unsanitary  surroundings  of  a  cow  barn   . 

72.  Conditions  under   which   it  is   difficult  to   cleanse  and   disinfect  milk 

bottles  and  milk  pails       ....... 

73.  A  dark,  poorly  ventilated  cow  shed,  difficult  to  keep  clean 

74.  Automatic  temperature  recorder  for  pasteurizers 

75.  Strauss  home  pasteurizer  ....... 

76.  Trichinella  spiralis.     Entire  life  cycle  in  each  host   . 

77.  Taenia  solium,  the  pork  or  measle  tapeworm     .... 

78.  Beef  tapeworm         ......... 

79.  Dibothriocephalus  latus,  the  fish  tapeworm        .... 

80.  Sections  through  seeds  of  rice,  wheat  and  corn 

81.  Portable  Haldane  apparatus  for  small  percentages  of  carbon  dioxid 

82.  Petterson-Palmquist   apparatus 

83.  Wolpert  air  tester  . 

84.  Fitz   air   tester 

85.  Diagram  showing  absolute  humidity 

86.  Sling  psychrometer 

87.  Eelative  humidity  table   . 

88.  Dew-point  apparatus 

89.  Table  showing  density  of  smoke,  in  accordance  with  the  Eingelmann 

chart,  which  may  be  emitted  from  the  various  classes  of  stacks  in 
Boston,  Mass.,  and  the  duration  of  such  emission 

90.  Magnus  aspirator     ....... 

91.  Double  aspirator      ....... 

92.  The  position  of  inlets  and  outlets,  and  their  relation  to  the  air  currents 

in   a   room        ......... 

93.  Window  ventilator   ......... 

94.  Diagrammatic   sketch   of  various  provisions  for  ventilation 

95.  The  nitrogen  cycle  ......... 

96.  The  nitrogen  cycle  in  diagrammatic  vertical  section   .  . 

97.  Ground    water  ......... 

98.  Usual  method  of  pollution  and  even  infection  of  wells 

99.  Proper  construction  of  a  well  ....... 

100.  Popular  idea  of  how  wells  become  infected  from  surface  pollution 

101.  Depression  of  the  ground  water  level  by  pumping  and  tendency  to  draw 

nearby  pollution  from  the  soil  or  cesspool 

102.  In   a  limestone   formation   it   is   difficult   to   tell   anything   about   the 

source  of  water  obtained  from  a  well       ....  -     815 

103.  Algae  commonly  found  in  water       .......     824 

104.  Algae  commonly  found  in  water       ,,...••     825 


510 
512 
514 
565 

569 
578 
584 
585 
629 
632 
633 
636 
650 
674 
676 
679 
680 

in  grains  at  different  temperatures     690 

694 
695 
696 


710 

718 
718 

757 
760 
761 
774 
775 
807 
811 
812 
813 

814 


xxxii  LIST  OF  ILLUSTRATIONS 

FIGURE  PAGE 

105.  The  oil  droplets  in  a  diatom     ........  826 

106.  Graduated   cylindrical    funnel    and    concentrating    attachment   used    in 

the    Sedgwick-Rafter    method    .......  856 

107.  Diagram  illustrating  the  character  of  ground  water  in  relation  to  soil 

pollution,  to  assist  in  the  interpretation  of  a  sanitary  analysis  .  868 

108.  Diagram  showing  location  of  samples        ......  877 

109.  Section  of  an  English  filter  bed       .......  884 

110.  The  arrangement  of  a  slow  sand  filter      ......  885 

111.  Diagram  illustrating   "loss  of  head"       ......  888 

112.  An  ozonizer     ............  898 

113.  An  installation  for  treating  water  with  ozone    .....  899 

114.  Asiatic  cholera  and  the  Broad  Street  pump,  London,  1854  .          .          .  927 

115.  Asiatic  cholera  and  the  Broad  Street  well,  London,  1854     .          .          .  929 

116.  Map  showing  Hamburg  water  supply        ......  931 

117.  Change  in  water  supply   .........  934 

118.  Mean  death  rates  from  typhoid  fever,  1902  to  1906,  in  66  American 

cities  and  7   foreign  cities         .......  935 

119.  Map  of  Plymouth,  Pa.,  in  1S85         .......  938 

120.  Map  showing  water  supply  of  Ashland,  Wis.     .....  940 

121.  Cross  section  of  septic  tank     .          .          ...          .          .          .          .  965 

122.  Typical  section  of  an  Imhoff  tank    .......  965 

123.  Chemical  precipitation  plant  at  Worcester,  Mass.,  outlet       .          .          .  967 

124.  Triple  contact  beds  at  Hampton,  England          .....  967 

125.  Cross  section  of  intermittent  sand  filter    ......  968 

126.  Inclined  screen  operated  by  water  wheel,  Birmingham,  England  .          .  968 

127.  Cross  section  of  contact  bed    ........  969 

128.  Typical   section  of  a  sprinkling  filter        ......  969 

129.  Trickling  filter  at  Birmingham,  England   ......  970 

130.  Septic  tank  and  chemical  precipitation  tanks  at  Eochdale,  England     .  974 

131.  Intermittent  sand  filtration  bed  at  Brockton,  Mass.   ....  977 

132.  Filter  bed  with  sand  ridged  for  winter  operation  at  Brockton,  Mass.  977 

133.  Discharge  of  sewage  upon  a  filter  bed  at  Brockton,  Mass.   .          .          .  978 

134.  Digestion  process  of  garbage  reduction       ......  982 

135.  A  simple  type  of  garbage  incinerator       ......  983 

136.  Cobwell  process  of  garbage  reduction,  New  Bedford,  Mass.        .          .  985 

137.  Births   (including  stillbirths),  persons  married  and  deaths   (excluding 

stillbirths)  registered  per  1,000  population  per  annum — Michigan, 

1871  to   1912 995 

138.  Smallpox — number  of  cases  notified  per  annum  in  Michigan,   1883  to 

1912 1002 

139.  Smallpox — number  of  cases  notified  per  annum  for  each  death  regis- 

tered, Michigan,  1883  to  1912 1003 

140.  Scarlet   fever — number   of   eases   notified   per   annum   for   each   death 

registered,  Michigan,  1884  to  1912 1006 


LIST  OF  ILLUSTRATIONS 


XXXlll 

PAGE 


FIGURE 

141.  Measles — number   of   cases  notified   per   annum  for   each   death  regis- 

tered, Michigan,  1890  to  1912 1010 

142.  Diphtheria — number  of  cases  notified  per  annum  for  each  death  regis- 

tered, Michigan,  1884  to  1912 1011 

143.  Births  and  deaths   (exclusive  of  stillbirths)    per  1,000  population  per 

annum,  registered  in  Massachusetts,   1871  to   1911       .  .  .  1023 

144.  Eed   oxid   of   lead   and   litharge   being   mixed    in   the   manufacture    of 

storage  batteries       .........  1037 

145.  An    effective    dust-removing    system    in    the     boot-and-shoe    industry. 

Edge  trimming  .........  1041 

146.  System    of   hoods    and   ventilators   to    carry    off    the    fumes    from    the 

furnaces   in   a   foundry      ........  1045 

147.  A  Avorker  with  lead  oxid,  showing  respirator  to  protect  himself  against 

the  poisonous  dust   .........  1051 

148.  The    stone    industry  .........  1055 

149.  Workmen  exposed  to  zinc  fumes  in  brass  casting,  causing  a  condition 

known  as  ' '  l)rass-f  ounder  's  ague "    .  .  .  .  .  .  1058 

150.  A  very  dusty  trade — drum  with  nails  which  combs  out  the  small  pieces 

of  broom   corn  .........  1067 

151.  Faulty  posture 1082 

152.  The  Heusinger  desk 1083 

153.  Boston  school  desk  and  chair    ........  1084 

154.  Bevice  for  determining  carbolic  coefficients        .....  1113 

155.  Section  through  Arnold  steam  sterilizer     .  .  .  .  .  .  1123 

156.  Section  through   autoclave         ........  1124 

157.  Bramhall-Deane   steam  sterilizer        .......  1124 

158.  Cross  section  through  steam  disinfecting  chamber      ....  1125 

159.  Longitudinal  section  through  steam  disinfecting  chamber    .  .  .  1127 

160.  Kinyoun-Francis   disinfecting   chamber      .  .  .  .  .  . .  1128 

161.  Automatic  thermometer    .........  1129 

162.  Plan  showing  the  method  of  installing  the  double-ended  steam  cham- 

bers  at  a  national   quarantine  station        .....  1130 

163.  Chart  showing  an  application  of  steam  under  pressure        .  .  .  1131 

164.  Flaring  top  tin  bucket  for  generating  formaldehyd  by  the  permanganate 

method 1136 

165.  The  pot  method   of  burning  sulphur  ......  1140 

166.  Large  stack  burner  for  sulphur,  with  15  of  the  18  pans  removed  to 

show  construction      .........  1141 

167.  Liquefied    sulphur   dioxid    in    tin    can  ......  1141 

168.  Section  through  double  sulphur  furnace    ......  1143 

169.  Camp  of  a  regiment  of  infantry       .  .  .  .  .  .  .  1196 

170.  The  normal  foot 1202 

171.  Shape  of  United  States  military  shoe 1202 

172.  A  rock  pile  crematory      .........  1208 


PREVENTIVE  MEDICINE 

SECTION  I 
PREVENTION  OF  THE  COMMUNICABLE  DISEASES 

CHAPTEE  I 

DISEASES   HAVING   SPECIFIC    OE   SPECIAL   PEOPHTLACTIC 

MEASUEES 

SMALLPOX  AND  VACCINATION 

The  prevention  of  smallpox  depends  primarily  upon  vaccination,  sec- 
ondarily upon  isolation  and  disinfection.  Vaccination  was  the  first 
specific  prophylactic  measure  given  to  man;  it  produces  an  active  im- 
munity to  smallpox  (variola).  On  account  of  its  importance  and  great 
practical  value  this  subject  will  be  considered  in  some  detail,  for  much 
of  the  antivaccination  sentiment  is  due  to  ignorance  or  misconstruction 
of  the  facts. 

Historical  Note. — The  credit  of  giving  vaccination  to  the  world  is 
due  to  Jenner,  who  proved  through  carefully  planned  experiments  that 
cowpox  protects  against  smallpox.  This  fact  had  been  familiar  to  the 
farmers  and  folk  of  England  as  a  vague  tradition  for  a  long  time.  A 
young  girl  who  sought  medical  advice  of  Jenner,  when  a  student  at 
Sudbury,  said,  "I  cannot  take  smallpox  because  I  have  had  cowpox" ;  this 
remark  made  a  strong  impression  upon  the  young  medical  student. 

Benjamin  Jesty,  a  Dorchestershire  farmer,  in  1774  successfully  vac- 
cinated his  wife  and -two  sons.  Plett,  in  Holstein,  in  1791  also  success- 
fully vaccinated  three  children.  It  was  Jenner,  however,  who  through 
logical  and  scientific  methods  proved  that  a  person  who  has  had  the 
mild  disease,  cowpox,  enjoys  protection  against  the  serious  and  often 
fatal  disease,  smallpox.  Waterhouse  and  others  soon  repeated  and  cor- 
roborated Jenner's  experiments  and  helped  to  establish  the  soundness 
of  his  conclusions. 

Jenner  made  his  crucial  experiments  in  1796,  when  he  transferred 
the  vaccine  matter  from  the  hand  of  a  dairy  maid   (Sarah  Nelms)  to 
3  1 


2 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


the  arm  of  James  Phipps,  a  boy  about  8  years  old.  Sarah  Nelms 
scratched  her  hand  with  a  thorn  and  "was  infected  with  the  cowpox 
from  her  master's  cows,  in  May,  179G."  Jenner  transferred  the  vaccine 
virus  from  the  eruption  upon  the  hand  of  Sarah  ISTelms  to  the  arm  of 
James  Phipps  on  May  14,  1796.  A  typical  take  followed.  "In  order 
to  ascertain  whether  the  boy,  after  feeling  so  slight  an  affection  of  the 
system  from  the  cowpox  virus,  was  secure  from  the  contagion  of  the 
smallpox,  he  was  inoculated  the  first  of  July  following  with  variolous 
matter,  immediately  taken  from  a  pustule.  Several  slight  punctures 
and  incisions  were  made  on  both  arms,  and  the  matter  was  carefully  in- 
serted, but  no  disease  followed.  The  same  appearances  were  observable 
on  the  arm  as  we  commonly  see  when  a  patient  has  had  variolous  mat- 
ter applied,  after  having  either  the  cowpox  or  the  smallpox.  Several 
months  afterward  he  was  again  inoculated  with  variolous  matter,  but  no 
sensible  effect  was  produced  on  the  constitution." 

In  addition  to  such  direct  experimental  proof,  Jenner  inoculated 
smallpox  matter  into  ten  persons  who  had  at  some  previous  time  con- 
tracted cowpox. 


Date  of  Inoculation 
with  Smallpox 

1.  1778 

2.  1791 

3.  1792 

4.) 

.  [1795 

D.C 

6. 

7.  Il797 


9. 
10. 


After  1782 
Not  stated 


Name 

Mrs.  H.  

Mary  Barge 
Sarah  Portlock 

S  Joseph  Merret 
William  Smith 
TElizabeth  Wynne 
J  Sarah  Wynne 
[William  Rodway 
Simon  Nichols 
John  Phillips 


Ascertained  to 
have  had  Cowpox 

When  very  young 
31  years  previously 
27  years  previously 
25  years  previously 
1,  5,  15  years  previously 
10  months  previously 
9  months  previously 
38  years  previously 
Some  years  previously 
53  years  previously 


In  justification  of  such  human  experimentation  it  should  be  re- 
membered that  at  that  time  the  inoculation  of  smallpox  matter  into 
healthy  individuals  was  an  acknowledged  method  of  preventing  that 
disease.  Jenner  himself  was  inoculated  when  a  boy.  The  question  of 
"inoculation"  (with  smallpox)  as  contrasted  with  "vaccination"  (with 
cowpox)  will  be  discussed  presently. 

With  such  proof  as  this  Jenner  put  a  popular  belief  upon  a  scien- 
tific basis.  He  demonstrated  that  cowpox  is  a  local  and  trivial  disease 
in  man,  that  it  may  be  readily  transferred  from  man  to  man,  and  that 
it  protects  against  smallpox.  The  chain  of  evidence  was  complete,  but 
he  first  proved  his  thesis  to  his  own  satisfaction  before  he  gave  it  to 
the  world.  He  said  himself:  "I  placed  it  on  a  rock  where  I  knew  it 
would  be  immovable  before  I  invited  the  public  to  take  a  look  at  it." 


SMALLPOX  AND  VACCINATION  3 

Jenner  presented  the  results  of  his  observations  to  the  Eoyal  Society,  of 
which  he  was  a  Fellow,  but  the  paper  was  refused.  He  then  published 
it  in  1798  as  a  book,  modestly  entitled,  "An  Inquiry  Into  the  Causes  and 
Effects  of  the  Variolae  Vaccinae,  a  Disease  Discovered  in  Some  of  the 
Western  Counties  of  England,  Particularly  Gloucestershire,  and  Known 
by  the  Name  of  the  Cowpox."  Every  student  of  preventive  medicine 
should  read  this  brief  "inquiry"  in  the  original.  It  may  be  taken  as  a 
model  of  careful  observation  and  logical  presentation,  showing  great 
self-restraint  and  moderation  of  an  observant,  Imaginative,  and  judicial 
mind. 

Dr,  Benjamin  Waterhouse,  the  first  professor  of  Theory  and  Prac- 
tice of  Physic  in  the  Harvard  Medical  School,  early  became  convinced 
of  the  value  of  Jenner's  demonstration  and  obtained  some  vaccine  virus 
on  threads  from  abroad.  On  July  8,  1800,  he  vaccinated  his  son,  Daniel 
Oliver  Waterhouse,  then  five  years  old.  This  was  the  first  person  vac- 
cinated in  America,  so  far  as  existing  records  show.  After  successful 
vaccination  his  two  sons  and  other  members  of  his  household  were  inocu- 
lated at  the  Smallpox  Hospital  by  Dr.  Zabdiel  Boylston,  with  negative 
results. 

In  Boston  on  August  16,  1802,  nineteen  boys  were  vaccinated  with 
the  cowpox.  On  November  9th  twelve  of  them  were  inoculated  with 
smallpox;  nothing  followed.  A  control  experiment  was  made  by  inocu- 
lating two  un vaccinated  boys  with  the  same  smallpox  virus;  both  took 
the  disease.  The  nineteen  children  of  August  16th  were  again  unsuc- 
cessfully inoculated  with  fresh  virus  from  these  two  boys.  This  is  one 
of  the  most  crucial  experiments  in  the  history  of  vaccination,  and  fully 
justified  the  conclusion  of  the  Board  of  Health — "cowpox  is  a  complete 
security  against  the  smallpox." 

Thomas  Jefferson  helped  materially  to  spread  the  new  doctrine  in 
this  country,  and,  in  1806,  in  writing  to  Jenner,  said :  "Future  nations 
will  know  by  history  only  that  the  loathsome  smallpox  has  existed  and 
by  you  has  been  extirpated."  This  prophecy  has  by  no  means  been  ful- 
filled— ^though  eminently  possible. 

VACCINATION 

Vaccination  may  be  defined  as  the  transference  of  the  virus  from 
the  skin  eruption  of  an  animal  having  vaccinia  or  cowpox  into  the  skin 
of  another  animal.  Vaccination,  then,  consists  in  introducing  the  active 
principle  of  cowpox  into  the  skin  of  a  susceptible  animal.  For  over 
one  hundred  years  vaccination  (from  vacca — a  cow)  was  a  specific  term 
limited  to  the  introduction  of  the  virus  of  cowpox  into  the  skin,  in  order 
to  induce  vaccinia  and  prevent  variola.  In  recent  years,  however,  the 
term  has  been  used  in  a  generic  sense  to  include  the  introduction  of 


4  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

many  different  substances  in  many  different  ways  and  for  many  different 
purposes.  Thus  we  speak  of  attenuated  or  killed  bacterial  cultures  as 
bacterial  vaccines;  and  the  subcutaneous  inoculation  of  organic  sub- 
stances of  diverse  origin  and  nature  is  often  spoken  of  as  vaccination. 
We  hear  of  typhoid  vaccines,  anthrax  vaccines,  staphylococcus  vaccines, 
and  we  read  in  the  literature  of  animals  "vaccinated"  with  extracts  of 
cancer  and  other  organic  substances.  For  distinction  between  a  vaccine 
and  a  virus,  see  page  396, 

VACCINE  VIRUS 

Vaccine  virus  is  the  specific  principle  in  the  matter  obtained  from 
the  skin  eruption  of  animals  having  a  disease  known  as  "vaccinia"  or 
"cowpox."  Vaccine  virus  is  obtained  from  calves,  man,  the  buffalo, 
sometimes  the  camel,  rabbits  and  other  animals. 

Cowpox,  or  vaccinia,  is  an  acute  specific  disease  to  which  many 
animals  are  susceptible,  namely,  man,  cattle,  camels,  rabbits,  monkeys, 
guinea-pigs,  rats,  etc.  The  disease  runs  practically  the  same  clinical 
course  in  all  susceptible  species.  The  eruption  is  always  ^  local  and 
confined  to  the  site  of  the  vaccinated  area;  the  constitutional  symptoms 
are  always  benign  and  usually  slight.  Vaccinia  or  cowpox  is  a  benign 
disease ;  when  uncomplicated,  it  has  never  been  known  to  cause  death  or 
leave  any  unpleasant  sequelae. 

After  an  incubation  period  of  from  three  to  four  days  the  local 
eruption  begins  as  a  papule  which  soon  develops  into  a  vesicle,  and 
later  into  an  umbilicated  pustule.  Surrounding  the  vesicle  is  a  red- 
dened, inflamed,  and  tender  areola.  The  neighboring  lymph  glands 
are  swollen  and  tender,  and  there  may  be  slight  fever  lasting  several 
days.  The  pustule  dries,  leaving  a  crust  or  scab,  which  comes  away,  dis- 
closing a  typical  f oveated  or  pitted  scar. 

Human  and  Bovine  Vaccine  Virus. — Vaccine  virus  is  usually  obtained 
from  (1)  bovine  or  (2)  human  sources. 

Human  virus  is  now  seldom  used,  for  the  reason  that  the  supply 
would  not  be  sufficient.  Upon  the  appearance  of  a  smallpox  outbreak 
it  is  sometimes  necessary  to  have  enough  virus  to  vaccinate  one  hundred 
thousand  or  more  people.  Such  large  quantities  evidently  could  not  be 
obtained  from  man  at  any  desired  time.  Another  objection  to  the  use 
of  human  virus  is  the  possibility,  although  small,  of  transmitting  syphilis, 
and  perhaps  other  diseases. 

When  human  seed  is  used  the  virus  may  be  transferred  directly  from 
arm  to  arm ;  or  the  virus  may  be  preserved  dry  in  the  scab ;  or  the  con- 
tents of  the  vesicle  may  be  kept  in  either  a  dried  or  moist  state,  as  de- 
scribed below  for  bovine  virus.  Arm-to-arm  vaccination  is  still  practiced 
in  several  parts  of  the  world,  particularly  in  Mexico,  where  it  is  claimed 

*  Rare  exceptions  to  this  statement  will  be  noted  later. 


SMALLPOX  A^B  VACCINATIOIsT  5 

that  it  has  the  advantage  of  producing  a  better  take ;  that  the  results  are 
surer  in  that  there  are  fewer  unsuccessful  vaccinations;  and,  finally,  it 
is  stated  that  the  human  virus  affords  a  better  immunity,  but  as  to  this 
there  is  no  proof  and  some  doubt. 

Bovine  virus  has  been  used  more  or  less  since  the  time  of  Jenner, 
but  especially  since  Copeman  showed  in  1891  how  to  purify  it  with 
glycerin.  It  has  the  great  advantage  of  being  readily  obtained  in  any 
amount  and  when  desired.  It  may  be  purified,  and  it  further  totally 
eliminates  the  danger  of  conveying  syphilis  and  other  diseases  peculiar 
to  man. 

Fornis  of  Vaccine  Virus. — Vaccine  virus  may  be  used  in  one  of 
three  forms:  (1)  fresh,  (2)  dry,  (3)  glycerinated. 

The  fresh  virus  may  be  taken  from  the  eruption  of  the  calf  or  man 
and  transferred  directly.  Thus  the  Institut  Vaccinale  at  Paris  still 
prefers  to  use  the  fresh  virus.  The  vesicle  is  squeezed  at  its  base  be- 
tween the  blades  of  forceps,  and  some  of  the  content  is  transferred 
directly  from  the  calf  to  the  skin  of  the  arm  by  means  of  a  thumb  lancet 
or  any  similar  instrument. 

The  vaccinal  matter  may  be  dried,  and  the  virus  remains  potent  in 
this  state  a  very  long  time,  especially  if  kept  cold  and  protected  from 
light.  The  virus  may  be  dried  upon  a  splinter  of  ivory  or  other  sub- 
stance. Formerly  physicians  preserved  the  dried  crust  from  a  typical 
take.  When  needed,  small  portions  of  this  crust  were  ground,  moistened, 
and  inserted  into  the  skin. 

Glycerinated  virus  consists  of  vaccine  pulp  treated  with  50  per  cent, 
pure  glycerin.  This  purifies  it  and  hence  is  preferable.  Before  taking 
up  the  question  of  glycerination,  we  must  understand  the  difference  be- 
tween vaccine  lymph  and  vaccine  pulp. 

Vaccine  Pulp  and  Vaccine  Lymph. — A  distinction  is  drawn  between 
the  pulp  and  the  lymph.  The  pulp  consists  of  the  entire  vesicle  with 
its  contents,  which  is  scraped  from  the  skin,  and  is  composed  of  epi- 
thelium, leukocytes,  bacteria,  products  of  inflammatory  reaction,  the 
fluid  content  of  the  vesicle,  debris,  etc.  The  lymph  is  the  serous  fluid 
contained  in  the  vesicle  or  which  often  exudes  from  the  broken  vesicle. 
When  the  eruption  is  produced  on  the  skin  of  a  calf  in  a  large  con- 
fluent area,  the  surface  of  the  eruption  is  scraped  away  and  the  exuding 
lymph  is  placed  upon  points  by  dipping  or  brushing. 

Most  of  the  active  principle  of  vaccine  virus  is  contained  in  the  epi- 
thelial cells,  and  this  portion  is  largely  lost  when  only  the  lymph  is  used. 
The  lymph  taken  after  the  8th  day  is  apt  to  produce  unduly  inflamed 
takes,  or  to  produce  abortive  vesicles,  called  spurious  takes  by  the  first 
vaccinators.  The  pulp,  which  includes  the  lymph,  therefore  contains 
the  virus  in  greater  concentration,  and  is  almost  exclusively  used  in  this 
country  at  the  present  time. 


6  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

Dry  Points  Versus  Glycerinated  Vaccine  Virus. — T}ie  old-fashioned 

dry  points  were  prepared  by  dipping.. splinters  of  ivory  into  the  vaccine 
lymph.  Later  the  lymph  was  collected  upon  a  brush  and  thus  trans- 
ferred to  the  tip  of  the  ivory  point.  Bone  or  glass  may  be  substituted  for 
ivory.  Bone  is  undesirable  because  it  is  difficult  to  sterilize.  The  only 
advantage  of  the  dry  point  is  its  convenience  in  vaccinating.  Its  dis- 
advantage is  that  the  virus  dried  upon  such  points  cannot  be  purified 
as  is  the  case  with  glycerinated  pulp.  Further,  the  points  are  used  as 
scarifiers  and  the  method  of  scarification  favors  irritation  and  infection 
of  the  wound.  The  dry  points  practically  always  contain  more  bacteria 
than  the  glycerinated  virus.  For  these  reasons  dry  points  are  no  longer 
permitted  in  interstate  traffic  in  accordance  with  the  federal  regulations. 

The  old-fashioned  dry  points  must  not  be  confused  with  certain 
points  containing  a  drop  of  glycerinated  lymph  now  placed  on  the  market 
by  manufacturers.  There  is  no  special  objection  to  these,  except  that  it 
encourages  vaccination  by  the  method  of  scarification.  Some  manufac- 
turers imitate  the  old-fashioned  dry  point  by  removing  most  of  the 
glycerin  from  the  ripened  pulp  by  pressing  it  between  blotting  papers. 
The  remaining  pulp  is  then  attached  to  the  points  with  sterile  dextrose, 
blood  serum,  or  some  other  gummy  substance. 

The  Process  of  Ripening. — When  the  vaccine  virus  is  fresh  it  is  said 
to  be  "green."  Glycerin  is  added  to  the  green  pulp,  and  after  it  has 
acted  a  certain  period  of  time  the  virus  is  said  to  be  "ripe."  The  use 
of  glycerin  for  this  purpose  was  introduced  by  Moncton  Copeman  ^  in 
1891  for  the  purpose  of  preserving  and  purifying  the  virus.  The  glycerin 
acts  as  a  ditferential  germicide,  that  is,  it  preserves  ^  the  active  prin- 
ciple in  the  vaccine  virus,  but  destroys  the  frail  non-spore-bearing  bac- 
teria. In  time  the  virus  itself  succumbs.  Vaccine  virus  must,  there- 
fore, not  be  used  while  green  nor  when  too  old.  Manufacturers  usually 
date  their  products  as  "not  reliable  after"  4  to  6  weeks  in  the  summer 
time,  and  3  months  during  the  cold  season. 

Fifty  per  cent,  glycerin  of  the  best  quality  is  used.  I  have  shown 
that  no  growth  of  bacteria,  yeasts,  or  molds  takes  place  in  60  per  cent, 
glycerin.  Two  to  four  parts  of  50  per  cent,  glycerin  are  added  to  1  part 
of  the  pulp  by  weight.  The  mixture  is  then  thoroughly  ground  with  a 
mortar  and  pestle  by  hand,  or  between  glass  rollers  in  a  special  mill 
driven  by  machinery.  The  pulp  should  be  thoroughly  broken  up  and  a 
uniform  suspension  obtained.  The  amount  of  glycerin  added  depends 
upon  the  consistency  and  character  of  the  pulp.  The  only  objection 
to  adding  more  glycerin  would  be  the  greater  dilution  of  the  virus,  and, 
therefore,  a  larger  proportion  of  negative  takes.     A  higher  percentage 

^Transactions  of  the  International  Congress  of  Hygiene,   1891. 
''Glycerin  also  serves  as  a  preservative  for  other  filterable  viruses,  as  foot- 
and-mouth  disease,  anterior  poliomyelitis,  rabies,  etc. 


SMALLPOX  AND  VACCINATION  7 

than  50  per  cent,  of  glycerin  soon  renders  the  virus  inert.  The  glycerin 
probably  destroys  the  bacteria  by  virtue  of  its  dehydrating  action.  The 
time  required  for  the  virus  to  ripen  depends  upon  the  temperature. 
Most  of  the  non-spore-bearing  bacteria  perish  in  30  days  at  15°  to  20°  C. 
Approximately  the  same  effect  may  be  obtained  at  37°  C.  in  a  few  hours. 
At  low  temperatures  the  glycerin  has  practically  no  bactericidal  effect. 
The  process  must  always  be  controlled  bacteriologically. 

Substances  other  than  glycerin  are  used  for  the  purpose  of  purifying 
vaccine  virus.  Carbolic  acid  (0.5  to  1.0  per  cent.)  is  used  with  success 
in  Japan,  and  to  some  extent  in  this  country.  Potassium  cyanid,  chloro- 
form, chlorobutanol,  etc.,  have  been  tried,  with  less  success  in  practice. 

Bacteria  in  Vaccine  Virus. — Vaccine  virus  obtained  from  the  skin 
always  contains  bacteria.  However,  the  bacteria  which  contaminate  vac- 
cine virus  are,  for  the  most  part,  harmless  to  man.  They  are  commonly 
those  that  are  found  on  and  in  the  skin  of  the  calf.  The  non-spore-bear- 
ing varieties  are  largely  eliminated  by  the  process  of  ripening.  There  are 
fewer  bacteria  in  the  typical  unbroken  vesicle  than  in  the  pustule  or  in  a 
broken,  crusty,  inflamed  eruption.  Green  virus  may  contain  from  a 
few  thousand  to  over  a  million  bacteria  per  cubic  centimeter.  The 
ripened,  glycerinated  virus  contains  much  fewer,  and  these  mostly  harm- 
less saprophytes.  The  number  of  such  bacteria  in  the  ripened  virus  may 
be  taken  as  an  indication  of  the  care  and  cleanliness  with  which  the  virus 
has  been  prepared.  Staphylococci,  streptococci,  members  of  the  hemor- 
rhagic septicemic  group,  and,  in  a  few  instances,  tetanus  spores  and  the 
gas  bacillus  have  been  found  in  vaccine  virus. 

Noguchi^  by  painstaking  methods  recently  obtained  a  bacteria-free 
vaccine  virus,  which  may  be  propagated  in  the  testicles  of  bulls  or  rab- 
bits. Human  beings  react  to  the  testicular  strain  in  an  entirely  typical 
manner  and  this  may  furnish  a  satisfactory  method  for  the  production 
of  a  safe  and  strong  vaccine  virus. 

Seed  Vaccine. — The  seed  virus  may  be  obtained  (1)  from  cowpox, 
(2)  from  smallpox,  (3)  by  retro  vaccination. 

"Spontaneous^'  or  casual  cowpox  occasionally  occurs ;  that  is  to  say,  the 
disease  appears  to  arise  spontaneously  because  its  origin  cannot  be  traced. 
Casual  cowpox  comes  either  from  another  case  of  cowpox  or  from  a 
case  of  smallpox.  Cattle  are  not  subject  to  smallpox,  but,  when  small- 
pox virus  is  introduced  into  the  skin  of  a  calf,  it  produces  cowpox. 
When  smallpox  is  thus  converted  into  cowpox,  it  remains  fixed  as  such, 
and  never  reverts  to  smallpox.^  In  several  instances  in  England,  Ger- 
many, and  this  country  the  seed  virus  has  been  obtained  by  starting 
cowpox  through  the  inoculation  of  smallpox  virus.     Such  virus  should 

''Jour,  of  Exp.  Med.,  June  1,  1915,  XXI,  6,  p.  339. 

^  It  is  highly  significant  that  casual  cowpox  was  formerly  much  more  com- 
mon when  smallpox  was  much  more  prevalent. 


8  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

not  be  used  until  several  transfers  from  calf  to  calf  have  been  made, 
for  the  reason  that  some  of  the  smallpox  virus  may  be  carried  over 
unaltered,  during  the  first  few  transfers. 

Retrovaccination  consists  in  carrying  the  vaccine  virus  back  from 
child  to  calf;  better  still,  the  virus  may  be  passed  from  man  through 
rabbit,  monkey,  or  other  susceptible  animal,  and  then  again  to  the  calf. 
Changing  the  species  helps  to  maintain  the  activity  of  the  vaccine 
virus  for  an  indefinite  time;  furthermore,  the  change  leaves  behind  cer- 
tain associated  bacteria  which  may  gather  increased  virulence  by  suc- 
cessive passage  from  animal  to  animal  of  the  same  species. 

Propagation. — In  the  propagation  of  bovine  virus  young  calves  are 
preferred,  because  they  are  more  manageable,  the  skin  is  more  tender, 
and  the  eruption  is  therefore  more  abundant  and  typical.  With  young 
animals  a  milk  diet  may  be  used,  which  simplifies  the  problem  of  dust 
contamination  from  dry  feed.  If  hay  or  fodder  is  used,  it  must  first 
be  autoclaved.  Either  heifers  or  bull  calves  are  suitable,  although  the 
former  are  preferred. 

The  animals  are  held  in  quarantine  for  seven  days,  under  observa- 
tion, to  determine  the  absence  of  infections  such  as  tuberculosis,  glan- 
ders, foot-and-mouth  disease,  tetanus,  fever,  diarrhea  or  skin  eruptions 
of  any  kind. 

Before  vaccinating  the  calf  it  is  carefully  cleaned,  and  the  site 
of  the  inoculation  is  shaved  and  prepared  surgically,  but  without  the 
use  of  germicidal  solutions.  Germicides  are  not  suitable  for  the  reason 
that  they  are  apt  to  destroy  the  vaccine  virus.  Cleanliness  and  asepsis 
are  the  watchwords.  The  area  selected  is  usually  the  abdominal  wall  be- 
tween the  tip  of  the  sternum  and  the  groin,  sometimes  including  the 
inner  side  of  the  thigh.  The  usual  method  is  to  make  long,  superficial 
incisions  in  the  skin  about  one  centimeter  apart,  and  the  seed  virus  is 
gently  rubbed  into  these  incisions.  The  calves  must  then  be  kept  rigidly 
isolated  in  a  special  room,  moderately  lighted,  free  from  dust,  and 
screened  to  keep  out  insects.  The  temperature  of  the  animal  is  taken 
several  times  daily,  and  the  eruption  at  each  stage  of  the  disease  is  closely 
watched  and  recorded. 

The  virus  is  usually  taken  from  the  animal  on  the  fifth  day.  It  is  an 
advantage  to  take  the  virus  as  early  as  practicable,  in  order  to  avoid  con- 
taminating infections  which  may  occur  when  the  vesicles  suppurate. 
Vaccine  virus  taken  after  the  eighth  day  is  unreliable.  Jenner's  golden 
rule  was  to  take  the  virus  before  the  areola  appeared.  Only  typical  and 
entirely  characteristic  vesicles  should  be  removed.  Before  the  virus  is 
removed,  the  animal  is  chloroformed  to  avoid  pain,  and  an  autopsy  is  done 
as  soon  after  the  virus  is  removed  as  practicable.  If  the  autopsy  shows 
any  lesions  indicating  infections  other  than  vaccinia,  the  virus  is  dis- 
carded. 


SMALLPOX  AND  VACCINATION  9 

It  is  not  wise  in  propagating  vaccine  virus  to  vaccinate  too  large 
an  area.  This  favors  infections  by  lowering  resistance ;  furthermore,  less 
typical  eruptions  are  obtained  than  when  the  area  vaccinated  is  moderate 
in  extent.  A  yield  of  from  twenty  to  twenty-five  grams  of  pulp  from  one 
calf  should  satisfy  the  propagator. 

Before  the  virus  is  taken  the  animal  is  placed  upon  a  special  table, 
the  site  of  the  vaccination  exposed  and  given  a  very  thorough  washing 
and  prolonged  scrubbing  with  soap,  and  an  abundant  flushing  with 
sterile  water.  The  pulp  is  obtained  by  scraping  the  vesicles  with  a 
sharp  spoon  curet. 

Glycerin  (50  per  cent.)  in  proper  proportion  is  added  at  once  to 
the  pulp,  and  this  is  ground  to  a  state  of  fine  and  uniform  subdivision  in 
a  Csokar  lymph  mill,  or  simply  by  hand  with  a  mortar  and  pestle.  This 
glycerinated  pulp  is  then  allowed  to  ripen,  and  when  ripe  it  is  hermeti- 
cally sealed  in  capillary  tubes,  or  placed  in  small  vials  for  the  market. 

METHODS  OF  VACCINATION 

Vaccination  consists  in  transferring  the  virus  of  cowpox  from  one 
animal  to  the  skin  of  another  animal.  The  operation  of  vaccination  con- 
sists of  introducing  vaccine  virus  into  the  skin.  Under  no  circvimstances 
must  the  vaccine  virus  be  placed  under  the  skin  or  subcutaneously.  The 
operation  may  be  compared  to  the  transfer  of  a  culture  in  a  bacteriologic 
laboratory.  Precisely  similar  precautions  to  prevent  contamination  must 
be  used  in  both  cases.  Vaccination  must  be  regarded  as  a  surgical  opera- 
tion. No  person  unfamiliar  with  surgical  cleanliness  should  be  per- 
mitted to  perform  this  "little"  operation. 

The  vaccine  virus  may  be  introduced  in  one  of  three  ways:  (1)  by 
puncture,  (2)  by  incision,  or  (3)  by  scarification. 

Jenner  used  punctures  or  short  incisions.  Later  blisters  were  raised 
upon  the  skin  and  the  virus  placed  upon  the  abraded  surface.  The 
incisions  were  then  increased  in  number,  and  finally  cross  scratchings 
or  scarifications  were  made. 

Puncture. — The  simplest  method  is  puncture  into  the  skin  with  a 
needle  moistened  with  the  vaccine  virus;  this  gives  little  chance  of  con- 
tamination and  the  eruption  is  typical.  The  disadvantage  is  that  the 
virus  now  used  is  diluted  with  glycerin,  and  therefore  somewhat  atten- 
uated, so  that  a  few  simple  punctures  are  less  apt  to  take. 

Incision. — The  method  advised  and  recommended  is  that  of  incision. 
Incision  is  the  only  method  of  vaccination  permitted  by  the  laws  of 
Germany,  and  recommended  by  the  Local  Government  Board  of  Eng- 
land. Incision,  if  not  too  deep,  consists  really  of  a  series  of  punctures, 
and  serves  the  same  purpose.  Incisions  may  be  made  with  the  point  of 
a  scalpel.     I  prefer  to  use  a  needle.     The  incision  or  scratch  should  not 


10        msEASEs  i-iAvma  special  prophylaxis 

be  deep  enough  to  draw  blood,  but  a  few  drops  do  no  harm.  It  is  rather 
difficult  to  control  the  depth  of  the  incision  with  a  scalpel,  especially 
if  it  is  sharp.  Scratching  with  a  needle  is  much  more  easily  controlled. 
The  incisions  should  be  about  one  inch  long  and  about  an  inch  apart. 
The  vaccine  virus  is  first  placed  upon  the  skin  in  two  small  droplets  about 
an  inch  apart.  The  point  of  the  needle  is  now  moistened  in  the  droplet 
and  as  the  scratch  is  made  the  needle  carries  the  virus  along  with  it 
into  the  little  wound.  With  the  flat  of  the  needle  the  virus  should  be 
gently  rubbed  (not  ground)  into  the  scratch.  It  is  important  not  to  cause 
any  unnecessary  irritation  so  as  to  avoid  attracting  infections. 

Scarification. — Scarification  or  cross-scratching  is  prohibited  in  Ger- 
many by  ministerial  decree  of  March  31,  1897,  which  was  incorporated 
into  the  revised  rules  of  the  Bundesrath,  July  28,  1898.  The  objec- 
tion to  scarification  is  that  this  method  produces  an  abraded  surface 
which  is  soon  covered  by  a  dry,  hard  crust  of  serum  and  blood,  through 
■which  the  eruption  cannot  pierce.  The  vesicles  form  a  ring  around  the 
scarified  area,  leaving  a  central  irritated  wound,  inviting  infection.  It 
is  believed  that  most  of  the  cases  of  tetanus  complicating  vaccination  oc- 
curred in  cases  in  which  scarification  was  used.  In  this  method  favor- 
able anaerobic  conditions  are  produced  under  the  crust  or  scab  which 
forms  over  the  abraded  surface. 

The  Point  of  Election. — The  outer  surface  of  the  left  arm  at  about 
the  insertion  of  the  deltoid  is  the  most  convenient  for  the  operator  and 
the  patient.  This  is  the  original  site  selected  by  Jenner,  and  is  less 
liable  to  severe  glandular  complications  than  other  points. 

Elachs  recommends  the  side  of  the  chest  at  about  the  level  of  the 
sixth  rib,  in  the  axilla.  Here  the  scar  is  not  visible;  there  is  little  mo- 
tion, and  it  is  easily  bandaged,  but  this  site  is  open  to  the  disadvantage 
of  greater  heat  and  moisture  and  there  is,  therefore,  greater  danger  of 
complications. 

The  leg  is  sometimes  selected  to  avoid  disfigurement.  The  vaccina- 
tion scar  should  not  be  regarded  as  a  deformity.  To  the  sanitarian  a 
typical  vaccine  scar  is  a  sanitary  dimple.  The  leg  is  more  exposed 
than  the  arm  to  traumatism,  and,  therefore,  to  complications.  Dock 
refuses  to  vaccinate  on  the  leg  unless  the  patient  will  stay  in  bed  until 
the  vesicle  heals.  With  babies  in  diapers  and  with  young  children  it  is 
exceedingly  difficult  to  keep  these  parts  clean.  If  the  leg  is  selected,  the 
vaccination  should  be  done  on  the  calf  below  the  head  of  the  fibula, 
and  not  on  the  outer  surface  of  the  thigh. 

Number  of  Incisions. — This  has  an  important  bearing  upon  the 
probability  of  the  take,  as  well  as  the  protection.  It  is  not  wise  to  de- 
pend upon  one.  There  is  a  definite  relation  between  the  number  of 
vesicles  and  the  degree  and  length  of  the  immunity  (see  page  17).  The 
German  regulations  of  1899  require  at  least  four  incisions,  each  one  cen- 


SMALLPOX  AND  VACCINATION 


11 


timeter  long  and  two  centimeters  apart.  The  Local  Government  Board 
of  England  directs  that  four  vesicles  should  be  produced,  and  that  the 
total  area  of  the  vesicle  formation  shall  not  be  less  than  one-half  a  square 
inch.  My  own  practice  follows  that  of  Dock,  who  makes  not  less  than 
two  incisions  about  an  inch  long  and  an  inch  apart;  but  in  case  of  ex- 
posure to  smallpox  three  or  four  such  incisions  are  advisable. 

The  Operation. — The  skin  at  the  site  of  the  operation  must  be  sur- 
gically clean,  but  need  not  necessarily  be  treated  with  antiseptics.  If 
such  are  used,  they  must  be  carefully  washed  away  in  order  not  to 
destroy  the  activity  of  the  virus.     A  thorough  preliminary  scrubbing 


Tig.  1. — ^Vaccination  Scars  Prodttced  by  Method  of  Scarification. 

with  soap  and  water  is  necessary  for  a  dirty  skin.  Washing  with  warm 
water  followed  by  alcohol  is  usually  enough.  The  alcohol  should  be  per- 
mitted to  evaporate  before  the  vaccine  is  applied  and  the  incision  is  made. 
In  general,  the  less  the  skin  is  irritated  the  less  the  danger  of  complica- 
tions. Needles  are  particularly  handy,  as  they  may  be  flamed  just  before 
the  operation,  and  are  convenient  in  saving  time  when  many  people  are 
to  be  vaccinated.  The  vaccine  virus  is  gently  rubbed  into  the  incision, 
not  ground  in,  and  then  allowed  to  dry.  No  dressing  is  necessary  at  the 
beginning,  but  several  layers  of  dry  sterile  gauze  held  in  place  by  adhe- 
sive plaster  do  no  harm,  and  serve  as  a  protection.  Pads,  plasters,  and 
shields  of  any  sort  are  unwise,  because  by  retaining  heat  and  moisture 
they  cause  a  softening  and  breaking  down;  in  other  words,  they  act  like 
a  poultice.  Bathing  need  not  be  omitted,  nor  any  of  the  ordinary  occu- 
pations, but  unnecessary  use  of  the  arm  must  be  guarded  against,  as  this 
increases  the  congestion,  inflammation,  and  the  chances  of  infection. 


INDICES  OF  A  SUCCESSFUL  VACCINATION 

The  take  must  be  typical  and  the  clinical  course  characteristic,  other- 
wise we  have  no  assurance  that  the  individual  is  protected  against  small- 
pox. The  best  indices  of  a  successful  take  are:  (1)  the  course  of  the 
eruption,  (2)  the  general  symptoms,  and  (3)  the  scar. 


12 


DISEASES  HAVING    SPECIAL   PKOPHYLAXTS 


The  importance  of  knowing  the  skin  lesions  of  vaccinia  were  in- 
sisted upon  by  Jenner.  Every  vesicle,  scab,  ulcer,  or  irritated  wound  is 
not  vaccinia.  No  confidence  should  be  placed  in  doubtful  or  atypical 
takes.  The  characteristic  features  of  vaccination  are  singularly  alike. 
The  clinical  course  of  a  primary  vaccination  is  as  follows : 

Course  of  the  Eruption.  — The  primary  wound  soon  heals.  Appar- 
ently nothing  occurs  for  3  to  4  days,  which  is  the  period  of  incubation. 


PUNCTURE 


PUSTULE  9THDAY 


PAPULE  4TW  DAY 


PES  I GC  AT  I O  N  12TH  DAY 


VESICLE  J"'"  DAY 


CRUST    I8TM0AY 


UMBILlCATION7T«DAY  FOV  EAT  ED  SCAR. 

Fig.  2. — The  Cotjkse  of  the  Ebuption  (Diagrammatic). 


Then  one  or  more  small  papules  appear  upon  the  skin  where  the  vac- 
cine virus  was  introduced.  The  papule  is  small,  round,  fiat,  bright 
red,  hard,  but  superficial.  About  the  fifth  day  the  summit  of  the  papule 
becomes  vesicular.  The  vesicle  is  at  first  clear  and  pearl-like.  Umbilica- 
tion  soon  develops  as  the  vesicle  enlarges.  A  deep,  red,  and  swollen 
areola  surrounds  the  vesicle  and  grows  wider  as  the  lesion  advances. 
This  gives  the  picture  of  the  "pearl  upon  the  rose  leaf"  which  consti- 
tutes the  true  jennerian  vesicle.  By  the  seventh  day  the  vesicle  is  full 
size,  round  or  oval,  fiat  on  top,  umbilicated,  and  contents  clear.     It  is 


SMALLPOX  AND  VACCINATION"  13 

multilocular ;  if  pricked  with  a  pin  or  accidentally  opened  only  that 
portion  of  the  lymph  contained  in  the  compartment  opened  will  exude. 
By  the  eighth  day  it  turns  yellowish,  the  middle  is  fuller,  following 
which  the  so-called  second  umbilication  develops.  Meanwhile  the  areola 
deepens,  widens,  and  may  be  swollen.  The  skin  feels  hot,  is  painful,  and 
the  axillary  glands  become  enlarged  and  tender.  About  the  ninth  day 
the  areola  begins  to  fade  and  the  swelling  subsides.  By  the  eleventh  or 
twelfth  day  the  pustule  rapidly  dries,  leaving  a  brown,  wrinkled  scab, 
which  finally  drops  off.  It  should  never  be  removed,  as  it  forms  the 
best  bandage. 

The  scar  is  at  first  red,  finally  turns  white,  with  the  pits  or  fovea- 
tions  so  characteristic  of  true  cowpox. 

General  Symptoms. — The  general  symptoms  vary.  There  are  malaise, 
loss  of  appetite,  sometimes  nausea  and  vomiting,  headache,  pain  in  the 
muscles  of  the  back,  and  other  indications  of  a  mild  febrile  reaction. 
The  temperature  may  go  to  38°  or  38.5°  C.  as  the  vesicle  ripens.  The 
febrile  reaction  bears  no  special  relation  to  the  size  and  number  of  the 
vesicles  or  to  the  areola.  The  regional  lymph  nodes  become  enlarged  and 
tender  about  the  time  the  pustule  forms.  The  nitrogen  elimination 
increases  about  the  tenth  day  for  a  short  time.  The  blood  changes  re- 
semble those  of  smallpox,  an  early  leukopenia  and  secondary  leukocytosis. 

Secondary  vaccinations  often  run  an  accelerated,  milder,  or  modified 
course  with  shortened  periods  of  incubation  (see  revaccination) , 

THE  IMMUNITY 

The  immunity  appears  about  the  eighth  day  of  the  vaccination. 
Layet  puts  the  point  of  safety  at  the  ninth  day,  Burckhard  at  the  elev- 
enth. These  data  are  based  upon  the  early  work  with  variolation,  when 
persons  were  inoculated  with  smallpox  at  various  periods  following  vac- 
cination. Sacco  got  only  a  local  eruption  by  inoculating  smallpox  on  the 
eighth  to  the  eleventh  days,  and  none  after  that. 

Vaccination  protects  not  only  against  smallpox,  but  also  against  vac- 
cinia. Curioiisly  enough,  the  degree  and  length  of  immunity  appear  to 
be  greater  against  smallpox  than  against  itself.  It  is  irrational  to  at- 
tempt to  fix  a  definite  time  for  the  duration  of  the  immunity.  This 
varies  as  in.  other  infectious  processes.  It  is  known  through  experiment 
and  experience  that  the  immunity  gradually  wears  off.  Definite  protec- 
tion on  the  average  lasts  about  seven  years.  The  degree  of  protection  is 
usually  absolute  for  some  years,  and  then  gradually  fades.  In  this,  as 
in  other  diseases,  immunity  is  a  relative  term.  Smallpox  itself  does  not 
always  protect  against  smallpox.  Some  people  have  two  and  even 
three  attacks  of  smallpox.^     Such  cases,  however,  are  exceptional,  and 

^  Jenner  mentions   "the   lady  of  Mr.   Gwinnett,   who   has   had  the  smallpox 
five  times." — Baron's  "Life  of  Jenner,"  Vol.  II,  p.  265. 


Eighth  Day 


Ninth  Day 


Fig.  3. — Vaccinia.    Course  of  the  Eruption  from  the  Fourth  to  the  Ninth  Day. 

14 


Fourteenth  Day 


Scar — Sixth  Week 


Fig,  4. — Vaccinia.    Course  of  the  Eruption  from  the  Tenth  Dat> 

15 


16 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


it  is  also  exceptional  to  have  smallpox  occur  in  an  individual  who  has 
been  properly  vaccinated. 


s 

In    Liverpool 

Sbcnvlns    the    rcloHvc    weverlty    c»f    the    . 
ThU    Dla^nun    ■•    tnMmi 
PIRSONB    VAOOINATED    IN    INFANCY. 


MALLPOX 

durlne:    ton    yoars    (I902-1911), 

dlt^c-Hsc    OB    It    arrccia    vacclnotcd    and    unvacclnaud    pervon*. 
on    «h*    rMor4a    of    Ilea    c»ms    of   ftmUlpox. 
,oox  ,™..  UN-VAOOINATED    PERSONS. 


Fig.  5. 


Note  : — 


1.  No  cases  of  Smallpox  under  2  years  of 

age. 

2.  Great  majority  of  persons  attacked  have 

the  disease  in  mild  form. 

3.  Gradual  loss  of  vaccination  immunity 

as  age  advances. 

4.  No  deaths  occur  until  later  life. 


Note  : — 

1.  Many  cases  occur  under  2  years,  and 

comparatively  large   proportion   of 
these  children  die. 

2.  No  influence  to  control  the  fatality  of  the 

disease,  except  the  recuperative  pow- 
er of  youth,  as  seen  from  10-30  yrs. 

3.  Deaths  very  numerous  in  children  under 

10  years,  and  persons  over  40  years. 


Careful  statistics  collected  in  Japan  since  1879  show  quite  definitely 
the  gradual  diminution  of  the  immunity,  beginning  with  the  second  year 
after  vaccination.    Kitasato's  table/  based  on  951  cases,  is  as  follows: 


SUCCESSFUL   REVACCINATION   AFTER: 

1  year 13.6  per  cent. 

2  years 32.9  "  " 

3  years 46.6  "  " 

4  years 57.3  "  " 

5  years 51.1  "  " 

6  years 63.8  "  *< 

VpMr.  A.  M.  A.,  March  2.5,   1911,  p.  889, 


SMALLPOX  AND  VACCINATION 


17 


Weil,  in  1899,  reported  72.5  per  cent,  of  successful  revaccinations 
after  seven  years,  80  per  cent,  after  eight  years,  85  per  cent,  after  nine 
years,  and  88.6  per  cent,  after  ten  years. 

It  is  commonly  asserted  that,  if  a  revaccination  takes,  the  subject  was 
therefore  susceptible  to  smallpox.  While  this  is  usually  true,  it  does  not 
necessarily  follow.  It  is  a  still  greater  fallacy  to  state  that,  if  a  vaccina- 
tion fails,  the  subject  is  therefore  immune.  This  view  may  result  in  real 
harm.  Vaccination  may  fail  for  many  reasons — the  operation  may  not 
have  been  properly  done,  or  the  virus  may  have  been  inert.  Sometimes 
persons  are  unsuccessfully  vaccinated  three,  four,  or  more  times  before 
a  typical  take  is  obtained.^ 

There  appears  to  be  a  definite  relation  between  the  immunity  con- 
ferred and  the  number  of  vaccination  scars.  There  is  also  some  evi- 
dence that  the  protection  is  directly  proportional  to  the  area  of  the  local 
eruption.  This  question  has  not  been  carefully  studied  since  the  data 
contained  in  the  final  Eeport  of  the  Koyal  Commission  on  Vaccination, 
which  is  summarized  in  the  following  table : 

MORTALITY  OF  POSTVACCINAL  SMALLPOX  IN  RELATION  TO  THE  NUMBER  OF  SCARS 


Number  of 
Scars 

3,094  cases* 
(1836-51) 

10,661  cases* 
(1852-67) 

6,839 
cases t 

None 

21.7% 

39.4% 

1 

7.6 

13.8 

6.2% 

2 

4.3 

7.7 

5.8 

3 

1.8 

3.0 

3.7 

4 

0.7 

0.9 

2.2 

*  Final  Report  of  the  Royal  Commission  on  Vaccination,  1896,  paragraph  291.     Dr.  Thome,  from 
data  collected  by  Mr.  Marson. 

t  Same  Report,  paragraph  293.     Summary  of  cases  apart  from  those  of  Mr.  Marson. 


One  point  needs  emphasis:  The  degree  and  duration  of  the  im- 
munity are  directly  proportional  to  the  typical  nature  of  the  take.  No 
reliance  should  be  placed  upon  atypical  reactions. 

The  nature  of  the  changes  in  the  body  which  produce  the  immunity 
are  not  understood.  In  this  sense  vaccination  is  still  an  empiric  pro- 
cedure. We  now  know  of  many  analogous  instances,  however,  where 
an  active  acquired  immunity  is  induced  by  means  of  an  attenuated  virus. 
The  immunity  produced  by  vaccine  virus  does  not  depend  upon  an  anti- 

^  One  of  my  cases  gave  a  history  of  having  been  unsuccessfully  vaccinated 
five  tiwiQS-     The  six^h  ^.ttempt  produced  a  typical  primary  take  with  21  vegiclea. 


18  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

toxin.  The  blood,  however,  contains  specific  antibodies,  shown  by  the 
fact  that  the  activity  of  vaccine  vims  is  destroyed  when  mixed  with 
equal  parts  of  blood  serum  from  a  calf  two  weeks  after  successful  vacci- 
nation. 

REVACCINATION 

The  fact  that  the  immunity  wears  off  after  a  number  of  years  makes 
it  necessary  to  practice  revaccination  in  order  to  afford  a  continuous 
protection.  There  is  some  difference  of  opinion  as  to  just  when  it  is 
best  to  vaccinate  the  second  time.  Ten  years  is  too  long  a  period,  prob- 
ably, to  depend  upon  in  individual  cases.  One  year — advised  by  some — 
is  shorter  than  necessary  in  most  cases.  The  five-year  interval  of  Japan 
is  good  in  many  respects,  but  probably  not  better  than  revaccination  in 
the  twelfth  year  obligatory  in  Germany. 

The  best  time  to  vaccinate  is  in  the  first  year  before  the  second  sum- 
mer, again  at  from  ten  to  thirteen  years.  After  this  it  is  usually  un- 
necessary to  vaccinate  again,  unless  there  is  particular  danger  of  expo- 
sure to  smallpox. 

All  persons  exposed  directly  or  indirectly  to  smallpox  should  at  once 
be  vaccinated — unless  they  have  had  the  disease  or  have  recently  been 
successfully  vaccinated.  There  are  no  contraindications  to  vaccinating 
babies  immediately  after  birth. 

The  clinical  picture  of  secondary  vaccinations  may  be  quite  different 
from  the  typical  take  following  a  primary  vaccination.  These  altered 
reactions  were  known  in  the  time  of  Jenner,  but  were  lost  sight  of  until 
recently  rediscovered,  and  their  significance  realized  from  studies  in 
anaphylaxis. 

Eevaccinations  may  be  divided  into  three  groups:  (1)  they  may  run 
an  unaltered  course  resembling  primary  takes  in  all  respects,  showing 
that  immunity  to  cowpox  has  disappeared;  (2)  they  may  run  a  somewhat 
more  rapid  course  in  which  the  period  of  incubation  is  shortened  and 
in  which  the  height  of  the  pustular  stage  occurs  about  the  sixth  day 
(this  is  known  as  the  accelerated  reaction) ;  or  (3)  they  may  run  a 
very  much  shortened,  milder,  and  rapid  course.  The  eruption  may  be 
pply  a  small  papule  which  does  not  develop  into  a  vesicle  and  soon  dis- 
appears; the  period  of  incubation  may  be  less  than  24  hours.  This  is 
knowp  as  the  imnaediate  reaction  and  resembles  a  cutaneous  tuberculin 
reaction  in  many  respects.  These  altered  reactions  have  been  studied 
.especially  by  von  Pirquet  and  are  shown  graphically  in  Fig.  6. 

The  immediate  reaction  may  be  pu.t  to  practical  use  in  order  to  dis- 
tinguish smallpox  from  chickenpox.  Thus,  Tieche  has  shown  that  small- 
pox virus  introduced  into  the  skin  of  a  person  immunized  by  vaccination 
will  show  the  typical  immediate  reaction;  whereas  the  virus  of  chicken- 
pox  is  invariably  negative.    This  test  can  be  freed  of  all  possible  danger 


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20  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

by  heating  the  virus  to  60°  C.  for  30  minutes,  which  does  not  seem  to 
affect  the  reaction, 

CLAIMS  FOR  VACCINATION 

1.  "Duly  and  efficiently  performed  it  will  protect  the  constitution 
from  subsequent  attacks  of  smallpox  as  much  as  that  disease  itself  will."  ^ 

2.  It  protects  the  individual  against  smallpox  for  a  period  which 
has  not  been  determined  mathematically  for  the  individual,  but  which 
averages  about  seven  years. 

3.  The  protection  may  be  renewed  by  a  second  vaccination. 

4.  Persons  successfully  vaccinated  on  two  occasions  are  usually 
immune  against  smallpox  for  life. 

5.  Vaccination  and  revaccination  systematically  and  generally  car- 
ried out  confer  complete  protection  to  a  community  or  a  nation.  In 
other  words,  while  the  individual  protection  is  not  always  perfect,  the 
communal  protection  is  absolute. 

6.  A  person  vaccinated  once  and  at  a  later  time  contracting  small- 
pox as  a  rule  has  the  disease  in  a  less  serious  form  than  unvaccinated 
persons  (varioloid).^  The  degree  of  favorable  modification  of  smallpox 
is  in  inverse  proportion  to  the  period  of  time  elapsing  between  the  vac- 
cination and  the  attack  of  smallpox. 

7.  The  beneficial  effects  of  vaccination  are  most  pronounced  in  those 
in  whom  the  vaccine  affection  has  run  its  most  typical  and  perfect 
course. 

VACCINATION  OF  EXPOSED  PERSONS 

The  question  frequently  arises  whether  persons  exposed  to  smallpox 
should  be  vaccinated.  The  effect  of  vaccination  during  the  period  of 
incubation  of  smallpox  is  very  interesting,  and  may  be  summed  up  as 
follows : 

1.  Vaccination  just  before  or  during  the  primary  fever  of  smallpox 
does  not  influence  the  disease. 

2.  If  the  vaccination  is  done  during  the  last  stage  of  the  period  of 
incubation  of  smallpox,  the  two  infections  run  their  course  side  by  side 
without  influencing  each  other. 

3.  If  it  is  done  about  the  sixth  or  eighth  day  of  the  period  of  in- 

*  "I  never  expected  that  it  would  do  more,  and  it  will  not,  I  believe,  do 
less." — Jenner.     Baron's  Life,  Vol.  II,  p.  135. 

^The  term  varioloid  was  introduced  by  Thompson  in  1820  to  describe  the 
mild  and  modified  form  of  smallpox  occurring  after  vaccination.  The  eruption 
in  varioloid  disappears  more  rapidly  than  in  variola. 

Yolfert,  Dornbleuth,  and  Harden  showed  that  one  vaccination  was  not  always 
sufficient  protection  against  smallpox  for  a  lifetime,  that  revaccination  was  neces- 
sary and  that  the  clinical  manifestations  of  this  vaccination  are  as  different  from, 
those  of  the  first  vaccination  as  varioloid  is  from  variola. 


SMALLPOX  AND  VACCINATION 


21 


cubation  the   vaccination  takes   and   may  modify  the   severity   of   the 
smallpox. 

4.  Vaccination  done  at  the  beginning  of  the  incubation  period,  in 
time  to  have  the  vaccine  eruption  reach  maturity  before  the  smallpox 
begins,  will  prevent  or  abort  the  disease.  This  is  shown  in  the  follow- 
ing diagram : 


THE  EFFECT  OF  VACCINATION  DURING  THE  PERIOD  OF  INCUBATION  OF  SMALLPOX 


Toward  the 

During  the 

Early  in  the 

Middle  of  the 

end  of  the 

Primary 

On  the 

Incubation 

Incubation 

Incubation 

Fever,  or 

First 

Period 

Period 

Period 

Preemption 

Day 

2nd  to  6th  days 

6th  to  8th  days 

9th  to  14th  days 

Stage 

-  Variola 

Prevents 

Smallpox  is 

Varioloid  or 

Smallpox  not 

Smallpox  not 

smallpox 

aborted 

mild  case 

influenced 

influenced 

1 

1 

MM! 

2    3    4     5    6 

\    I 

1        1        1        1        1        1 
9     10    11     12    13    14 

III 
1       2       3 

1 

Period  of 

M   M    1 

Incubation  of  f 

mallpox — ^in  Days 

1        1        1        1        1        1 

Primary  Fever        Eruption 

The  vaccina- 

The vaccina- 

The vaccina- 

The vaccination  takes 

The    vaccination 

tion  takes. 

tion  takes. 

tion  takes  2 
or  4  days  be- 
fore primary 
fever. 

and    both    affections 
run  side  by  side. 

does  not  take  (?) 

To  produce  the  best  results  the  vac- 

"Vaccinia 

cination  should  precede   this  period, 

so  as  to  reach  maturity  before  the 

onset    of    the    primary    fever.     The 

vaccine  vesicle  reaches  maturity  about 

the  8th  day. 

_ 

As  we  can  never  be  quite  sure  Just  what  stage  in  the  period  of  in- 
cubation a  given  case  may  be  in,  it  is  always  advisable  to  vaccinate 
exposed  persons.  Furthermore,  little  harm  will  be  done  if  it  is  too 
late  and  the  vaccine  eruption  is  added  to  the  smallpox.  Indeed,  Hanna^ 
presents  claims  to  the  effect  that  there  is  evidence  in  mitigating  the 
severity  of  smallpox  when  vaccination  is  performed  at  any  time  after 
infection  up  to  the  day  of  onset  and  even  afterward. 

DANGERS  AND  COMPLICATIONS 

The  alleged  danger  from  vaccination  has  been  greatly  magnified  by 
the  antivaccinationists.  However,  vaccination  is  not  always  a  harmless 
procedure ;  it  must  be  looked  upon  as  the  production  of  an  acute  infec- 
tious disease,  and,  although  the  disease  is  always  mild  and  benign,  it 
must  not  be  treated  as  trifling.     The  chief  danger  lies  in  the  fact  that 

'Public  Health,  July,  1910,  XXIII,  No.  10,  p.  351. 


23  DISEASES  HAVING  SPECIAL  PKOPHYLAXIS 

we  have  produced  an  open  wound,  wliicli  is  subject  to  the  complications 
of  any  wound.  Even  a  pin  prick  or  a  razor  scratch  may  result  in  death. 
While  the  aggregate  number  of  deaths  resulting  from  the  complications 
of  vaccination  may  be  considerable,  the  individual  risk  is  so  small  as  to 
be  disregarded,  especially  when  proper  precautions  are  taken.  Many 
of  the  infections  after  vaccination  occur  in  those  in  whom  the  regard 
for  cleanliness  is  slight,  and  who  neglect  the  care  of  the  wound.  In 
recent  years,  owing  to  the  improved  quality  of  the  vaccine  virus  and 
the  introduction  of  aseptic  methods,  a  bad  sore  arm  is  a  rare  occurrence, 
and  serious  complications  still  rarer.  In  any  case,  the  danger  connected 
with  vaccination  is  infinitesimal  when  compared  tuith  the  benefit  con- 
ferred.   The  important  complications  are : 

Auto  Vaccination. — This  is  usually  due  to  scratching  the  virus  with 
the  finger  into  the  nose,  the  mouth,  the  mucous  membranes,  or  any  part 
of  the  skin.  When  carried  into  the  eye  it  may  cause  blindness.  Physi- 
cians sometimes  vaccinate  their  lips  by  blowing  into  vaccine  tubes.  In 
vaccine  establishments  accidental  vaccination  of  the  hand  is  common. 

Generalized  Vaccination. — This  is  sometimes  reported,  but  is  usu- 
ally a  mistaken  diagnosis.  A  generalized  eruption  of  cowpox  is  ex- 
ceedingly rare,  if  it  ever  occurs.  I  have  seen  it  in  the  calf  after  intra- 
venous injection  of  a  large  amount  of  the  virus,  in  which  case  there  is 
a  prolonged  period  of  incubation. 

Wound  infections,  such  as  ulcers,  gangrene,  erysipelas,  abscesses, 
lymphangitis,  suppuration  of  the  axillary  glands,  and  other  septic  infec- 
tions are  now  exceedingly  rare,  and  demand  the  usual  surgical  measures 
to  prevent  their  occurrence. 

Impetigo  contagiosa  occasionally  occurs  and  may  be  a  serious  com- 
plication of  vaccination,  especially  the  bullous  impetigo  or  pemphigoid 
forms,  which  presumably  have  their  origin  in  cattle. 

(Syphilis,  tuberculosis,  and  leprosy  are  sometimes  feared,  but  these 
are  impossible  with  the  use  of  bovine  virus.) 

Tetanus. — Tetanus  deserves  a  special  word.  This  serious  and  fre- 
quently fatal  infection  sometimes  complicates  a  vaccination  wound  just 
as  it  may  any  wound.  When  we  consider  the  many  millions  of  vaccina- 
tion wounds,  many  of  which  are  neglected  surgically,  it  is  no  surprise 
to  learn  that  tetanus  occasionally  occurs  as  a  postvaccinal  complication. 
Acland  is  acquainted  with  only  one  instance  in  more  than  five  million 
consecutive  vaccinations  in  England,  and  even  in  this  one  there  was  no 
evidence  that  the  tetanus  was  invaccinated.  Over  31,000,000  doses  of 
vaccine  virus  were  used  in  the  United  States  from  1904  to  1913  inclusive, 
yet  only  41  authenticated  cases  of  tetanus  occurred  subsequent  to  vac- 
cination.^   A  study  of  these  cases  makes  it  clear  that  the  infective  prin- 

^J.  F.  Anderson:  United  States  Public  Health  Report,  Reprint  289,  July 
16,  1915. 


SMALLPOX  AND  VACCINATION  23 

ciple  was  not  in  the  vaccine  virus,  but  was  received  ten  days  or  more 
after  vaccination,  owing  to  the  prolonged  period  of  incubation  (20.7 
days)  and  the  high  mortality  (75.2  per  cent.).  Many  of  the  cases  fol- 
lowing vaccination  give  a  history  of  having  the  vaccination  scab  or  crust 
removed  in  some  way,  thus  permitting  infection  of  the  wound  with  a 
reformation  of  the  crust  and  the  establishment  of  an  anaerobic  condi- 
tion. The  fact  that  lack  of  care  is  an  important  factor  in  postvaccinal 
tetanus  is  indicated  in  the  figures  from  the  United  States  Army  and 
Navy  with  a  record  of  585,000  vaccinations  without  a  single  case  of 
tetanus.  At  the  Hygienic  Laboratory  at  Washington  many  hundred 
samples  of  vaccine  virus  representing  a  million  and  a  half  vaccinations 
have  been  examined  without  finding  a  tetanus  spore  in  a  single  vaccine 
point  or  tube.  Special  tests  for  tetanus  are  required  by  Federal  regula- 
tions of  every  lot  of  vaccine  virus  before  it  is  placed  upon  the  market. 
In  the  Vaccine  Laboratory  of  the  State  Department  of  Health  of  Mas- 
sachusetts, of  which  I  have  charge,  these  tests  are  conducted  in  accord- 
ance with  the  recommendation  of  Francis,^  as  follows : 

(a)  Plant  0.25  c.  c.  virus  into  fermentation  tubes  of  glucose  bouillon 
and  incubate  immediately.  Inject  0.25  c.  c.  of  the  growth  at  the  end  of 
9  days  subcutaneously  into  mice. 

(b)  Plant  0.25  c.  c.  vaccine  virus  into  fermentation  tubes  of  glucose 
bouillon,  heat  at  60°  C.  for  one  hour  and  then  incubate.  Inject  0.25  c.  c. 
of  the  growth  into  mice  at  the  end  of  9  days. 

(c)  Plant  0.25  c.  c.  vaccine  virus  into  fermentation  tubes  of  ordi- 
nary bouillon,  containing  a  bit  of  sterile  tissue,  and  inject  0.25  c.  c.  of 
the  growth  at  the  end  of  9  days  into  mice. 

(d)  Inject  0.25  of  the  vaccine  virus  subcutaneously  into  guinea-pigs. 
If  tetanus  spores  are  present  in  the  virus,  one  of  these  four  methods 

is  almost  sure  to  detect  them. 

The  occurrence  of  occasional  stray  tetanus  spores  in  vaccine  virus 
was  demonstrated  by  Carini.^  Such  vaccine,  however,  had  proved  en- 
tirely harmless  in  thousands  of  cases.  Francis  also  showed  the  vaccine 
virus  purposely  contaminated  with  tetanus  spores  will  not  produce 
tetanus  in  monkeys,  although  it  will  produce  typical  "takes."  Willson  ^ 
in  1902  claims  to  have  found  tetanus  spores  in  the  vaccine  virus  used  in 
the  New  Jersey  episode. 

Glycerin  does  not  destroy  the  tetanus  spore,  and  while  the  occa- 
sional danger  cannot  be  denied  it  is  plain  that  postvaccinal  tetanus 
should  usually  be  laid  to  lack  of  care  and  neglect  of  the  vaccination 
wound. 

To  prevent  tetanus  complications  it  is  important  to  avoid  scarifica- 

^  Edward   Francis,   "Laboratory   Studies   on   Tetanus,"   Hygienic   Laboratory 
Bull.,  No.  95,  August,  1914,  U.  S.  Public  Health  Service. 
^Centralbl.  f.  Bakt.,  Orig.  1904,  XXXVII,  p.   1147. 
Vo«r.  A.  M.  A.,  1902,  XXXVIII,  p.  1147. 


24  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

tion  and  irritation,  also  to  avoid  the  use  of  shields  and  bandages  which 
favor  anaerobic  conditions,  to  require  the  patient  to  use  strict  cleanliness, 
and  to  use  vaccine  virus  that  has  been  properly  prepared  and  tested. 

Foot-and-Mouth  Disease. — The  infection  of  foot-and-mouth  disease 
has  in  one  instance  been  demonstrated  as  a  contamination  of  vaccine 
virus.^  It  is,  however,  impossible  to  convey  foot-and-mouth  disease  to 
man  through  cutaneous  inoculation.  While  no  harm  has  been  done  to 
man,  the  contamination  is  undesirable,  and  special  Federal  regulations 
now  require  vaccine  virus  to  be  tested  from  time  to  time  to  assure  its 
freedom  from  this  infection. 

As  an  illustration  of  how  seldom  complications  are  caused  by  vac- 
cination we  have  the  results  of  Germany,  where  in  thirteen  years  (1885- 
1893)  32,166,619  children  were  vaccinated.  Of  these  115  died  within 
a  few  weeks  or  months  after  the  operation,  presumably  of  injuries  in- 
cidental thereto.  Of  these  at  least  48  probably  did  not  die  as  a  direct 
result  of  the  vaccination. 

The  figures  of  recent  years  are  still  better,  for  it  is  now  exceedingly 
rare  for  a  death  to  be  recorded  as  directly  due  to  vaccination.  For 
example,  in  the  Philippine  Islands  in  the  past  few  years  the  United 
States  authorities  vaccinated  3,515,000  persons  without  a  single  death 
or  any  serious  postvaccinal  complications. 

THE  GOVERNMENT  CONTROL  OF  VACCINE  VIRUS 

By  the  law  of  July  1,  1902,  the  vaccine  virus  sold  in  interstate  traf- 
fic in  the  United  States  must  come  from  a  licensed  manufacturer. 
These  licenses  are  issued  by  the  Secretary  of  the  Treasury  only  after  a 
careful  inspection  of  the  plant,  personnel,  and  product  by  a  competent 
government  officer.  The  licenses  are  good  for  one  year  only,  and  are 
reissued  only  after  reinspection.  The  government  regulations  require 
each  lot  of  vaccine  virus  to  be  examined  carefully  by  modern  bacterio- 
logical methods  to  determine  the  number  of  bacteria,  and  special  tests 
must  be  made  to  determine  the  absence  of  pathogenic  microorganisms. 
These  tests  include  animal  inoculations,  as  well  as  cultural  methods. 
Special  tests  for  each  lot  of  vaccine  must  be  made  to  determine  the 
presence  or  absence  of  streptococci,  tetanus  spores,  the  gas  bacillus,  and 
other  pathogenic  microorganisms,  etc.  The  government  does  not  guaran- 
tee the  purity  and  potency  of  each  package  of  vaccine  virus,  but  through 
its  inspections  and  frequent  examinations  of  the  virus  on  the  market 
every  confidence  may  now  be  had  in  the  vaccine  virus  propagated  by 
licensed  manufacturers  in  this  country. 

1  Mohler  and  Rosenau,  U.  S.  Dept.  of  Agriculture,  B.  A.  I.  Circular  147,  June 
16,  1909. 


SMALLPOX  AND  VACCINATION  35 

THE  UNITY  OF  COWPOX  AND  SMALLPOX 

The  unity  or  duality  of  these  two  diseases  has  been  the  subject  of 
much  contention.  Jenner  originally  considered  cowpox  to  be  a  modified 
smallpox.^  The  successful  experiments  in  Germany,  England,  and  this 
country,  in  which  smallpox  has  actually  been  modified  by  passing  vari- 
olous matter  through  calves  has  proved  positively  that  we  are  dealing 
with  two  forms  of  one  disease.  Much  of  the  vaccine  virus  used  during 
the  past  hundred  years  was  originally  obtained  from  cases  of  casual 
cowpox.  This  virus  has  been  shown  by  experience  and  experiments  to 
protect  against  smallpox,  which  again  makes  it  highly  probable  that  we 
are  dealing  with  one  disease.  The  parasite  Cytorrhyctes  variolae  de- 
scribed by  Councilman,  Brinckerhoff,  and  Tyzzer,  gives  a  probable  ex- 
planation of  how  smallpox  may,  under  certain  circumstances,  become 
attenuated.  The  life  cycle  of  this  parasite  interpreted  by  Calkins  indi- 
cates that  the  mild  disease,  cowpox  or  vaccinia,  is  due  to  the  asexual 
phase  in  the  life  cycle  of  the  parasite  which  lives  and  multiplies  in  the 
cytoplasm  of  the  epithelial  cell;  smallpox  is  caused  by  the  combined 
asexual  and  sexual  cycle  of  the  same  parasite,  the  latter  phase  occurring 
in  the  nucleus  of  the  epithelial  cell.  When  the  Cytorrhyctes  variolae  loses 
its  power  to  generate  by  sexual  division  it  never  again  regains  it ;  that  is, 
while  smallpox  may  be  modified  into  cowpox,  cowpox  has  never  been 
returned  to  smallpox. 

It  seems  plain  that  the  so-called  casual  cowpox  has  its  origin  from 
smallpox  through  accidental  inoculation  in  milking  cows  by  persons  hav- 
ing or  recovering  from  smallpox.  Once  started,  the  propagation  of  the 
modified  virus  from  cow  to  cow  would  be  comparatively  simple. 

COMPULSORY  VACCINATION 

Vaccination  affords  a  high  degree  of  immunity  to  the  individual,  and 
a  well-nigh  perfect  protection  to  the  community.  To  remain  unvac- 
cinated  is  selfish  in  that  by  so  doing  a  person  steals  a  certain  measure  of 
protection  from  the  community  on  account  of  the  barrier  of  vaccinated 
persons  around  them. 

The  laws  ^  and  regulations  relating  to  vaccination  in  the  several 
states  of  the  United  States  show  marked  lack  of  uniformity.  Compulsory 
general  vaccination  can  be  said  to  exist  by  law  only  in  Kentucky,  Ehode 

*  Smallpox  is  a  disease  subject  to  mutations.  Since  1898  a  mild  form  of 
smallpox  has  existed  in  this  country  with  a  death-rate  of  about  0.5  per  cent. 
This  mild  form  shows  no  tendency  at  present  to  increase  in  virulence.  Chicken- 
pox  itself  may  belong  to  the  smallpox  family.  The  two  diseases  are  sometimes 
indistinguishable  at  the  bedside.  Jenner  always  considered  cowpox  and  smallpox 
as  modifications  of  the  same  "distemper,"  and  in  using  vaccine  lymph  he  was 
impregnating  the  constitution  with  the  disease  in  its  mildest  form  instead  of 
propagating  it  in  its  virulent  and  contagious  form. 

^  Kerr,  J.  W.,  "Vaccination,  and  Analysis  of  the  Laws  and  Regulations  Re- 
lating Thereto  in  Force  in  the  United  States,"  Public  Health  Bull,  52, 


26 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


Island,  and   Porto  Rico.^     Arizona,  Hawaii,   Maryland,  New  Mexico, 
North  Dakota  have  laws  requiring  vaccination  of  children. 

Decisions  in  the  various  courts  in  the  United  States  have  held  com- 
pulsory vaccination  to  be  legal.  A  decision  of  the  Supreme  Court  of 
the  United  States  (Henning  Jacobson  vs.  The  Commonwealth  of  Massa- 
chusetts, April  1,  1905)  upheld  in  every  respect  the  statute,  the  validity 
of  which  was  questioned  under  the  Constitution : 

The  liberty  secured  by  the  Constitution  of  the  United  States  .... 
does  not  impart  an  absolute  right  in  each  person  to  be,  at  all  times,  and  in 
all  circumstances,  wholly  freed  from  restraint.  Real  liberty  for  all  could 
not  exist  under  the  operation  of  a  principle  which  recognizes  the  right  of 
each  individual  person  to  use  his  own,  whether  in  respect  to  his  person  or 
his  property,  regardless  of  the  injury  that  may  be  done  to  others. 

Theoretically  it  would  be  ideal  if  all  persons  submitted  to  vaccination 
and  revaccination  voluntarily.  But  experience  has  shown  that  this  is 
impractical,  and,  wherever  tried,  has  failed.  The  best  results  have  always 
been  obtained  where  vaccination  has  been  compulsory,  and,  in  my  judg- 
ment, this  is  the  only  present  means  by  which  smallpox  may  be  elim- 
inated. 

The  world  may  learn  a  valuable  lesson  from  the  splendid  results 
obtained  in  Germany  through  compulsory  vaccination  and  revaccination. 
In  England  the  '^conscience  clause"  allows  many  persons  to  remain 
unvaccinated  and  thereby  seriously  diminishes  the  effects  of  the  vacci- 

TABLE  1.— DEATHS  FROM  SMALLPOX  IN  COUNTRIES  WITH  COMPULSORY  VACCINA- 
TION AND  THOSE  WITHOUT  COMPULSORY  VACCINATION 


Population 


Smallpox  Deaths 

Average 

of 

1886 

1887 

1888 

1889 

Deaths 

1 

5 

9 

2 

4 

2 

14 

3 

0 

5 

24 

17 

0 

6 

12 

197 

168 

112 

200 

169 

275 

505 

1,026 

23 

458 

182 

14 

17 

3 

54 

1,213 

610 

865 

1,212 

975 

16,938 

25,884 

? 

? 

21,411 

8,794 

9,591 

14,138 

12,358 

11,220 

? 

16,249 

18,110 

13,416 

15,925 

? 

? 

14,378 

8,472 

11,425 

Average  per 
Million  of 
Popxilation 


Sweden* 4,746,465 

Ireland* 4,808,728 

Scotland* 4,013,029 

Germany* 47,923,735 

England* 28,247,151 

Switzerland 2,922,430 

Belgium 5,940,365 

Russia 92,822,470 

Austria 23,000,000 

Italy 29,717,982 

Spain 11,864,000 


1 
1 
3 

3.5 
16 

18.5 
164 
231 
510 
536 
963 


*  Compulsory  vaccination. 

^Massachusetts,  in  1809,  was  the  first  state  to  enact  legislation  relative  to 
vaccination. 


SMALLPOX  AND  VACCINATION 


27 


nation  laws  of  that  land.  In  Minnesota  the  state  health  authorities 
became  weary  of  the  clamor  against  compulsory  vaccination  and  assisted 
in  having  the  law  repealed.  They  said,  in  substance,  to  the  people  of 
the  state:  "Take  your  choice.  Be  vaccinated  and  protect  yourself,  or 
run  the  risk  of  contracting  smallpox ;  if  you  get  it,  it  is  your  own  fault." 


INOCULATION  OB  VARIOLA  INOCULATA 

The  practice  of  inoculation  must  be  carefully  distinguished  from 
that  of  vaccination.  By  inoculation  we  mean  the  introduction  of  small- 
pox matter  into  the  skin  of  man.  The  disease  thus  produced  is  usually 
mild,  but  is  nevertheless  true  smallpox,  and  just  as  contagious  as  small- 
pox. 

This  phase  of  the  subject  may  be  made  clearer  by  considering  small- 
pox as  existing  in  three  forms :  ( 1 )  variola  vera  or  true  smallpox ;  ( 2 ) 
variola  inoculata  or  inoculated  smallpox;  (3)  vaccinia,  cowpox,  or  modi- 
fied smallpox.  The  differences  between  these  affections  are  shown  in  the 
following  table : 


Variola  Vera 

Variola  Inoculata 

Vaccinia  or  Cowpox 

True  smallpox. 

Inoculated  smallpox. 

Modified  and  attenuated  smallpox. 

Only  occurs  in  man. 

Occurs  in  man  and  monkeys. 

Man,  monkeys,  cattle,  guinea- 
pigs,  rabbits,  rats,  camels,  and 
many  other  mammals. 

High  mortality. 

Milder;  rarely  fatal;  about  1  in 
500. 

Very  mild;  never  fatal. 

A  general  eruption,  often 
confluent     or     hemor- 
rhagic. 

A  local  and  a  general  eruption, 
fewer    pustules    (rarely    over 
200) ;     seldom     confluent     or 
hemorrhagic. 

Always  local  and  confined  to  the 
site   of   the   vaccination. 

Highly  contagious  _ 

Equally  highly  contagious. 

Not  contagious  —  contracted  only 
by  mechanical  transfer  of  vac- 
cine virus. 

Period  of  incubation  12-14 
days. 

8  days. 

3-4  days. 

28  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

Emphasis  must  be  placed  on  the  fact  that  variola  inoculata,  while 
usually  a  mild  disease,  is  just  as  communicable  as  true  smallpox,  and 
those  who  contract  the  disease  in  this  way  get  true  smallpox,  sometimes 
in  serious  or  fatal  form.  Inoculation,  therefore,  protects  the  individiuil 
but  endangers  the  community. 

Inoculation  is  a  very  old  custom.  It  was  practiced  by  the  Chinese 
from  time  immemorial.  The  method  was  introduced  into  western  civili- 
zation through  Lady  Mary  Wortley  Montagu,  who  learned  of  the  method 
at  Constantinople  and  had  her  own  boy  "engrafted"  with  successful  re- 
sult. In  1717  Lady  Montagu  wrote  her  now  famous  letter  to  her  friend 
Sarah  Chiswell,  and  the  practice  soon  became  popular  in  England 
(1721)  and  spread  to  America  and  the  Continent.^  It  was  introduced 
into  this  country  by  Dr.  Zabdiel  Boylston  at  Boston.  But  the  dangers 
were  early  realized  and  inoculation  was  soon  replaced  by  vaccination. 
According  to  Plehn,  inoculation  is  still  practiced  in  central  Africa. 

The  method  of  inoculation  is  precisely  similar  to  that  of  vaccina- 
tion. The  matter  is  obtained  from  the  vesicle  or  pustule  of  a  case  of 
smallpox.  This  material  is  then  introduced  into  the  skin  by  means  of 
a  puncture,  an  incision,  or  through  an  abraded  surface.  The  Chinese 
inoculate  usually  by  plugging  the  nostrils  with  cotton  previously  sat- 
urated with  a  mixture  of  water  and  pustular-crustaceous  matter  taken 
from  the  eruption  of  a  smallpox  patient;  less  commonly  by  blowing  the 
crushed  fresh  crusts  into  the  nostrils  through  a  bamboo  pipe. 

Following  the  inoculation  of  smallpox  virus  a  local  eruption  appears 
on  the  fourth  day  at  the  site  of  the  inoculation.  This  local  eruption 
resembles  vaccinia  but  develops  more  rapidly.  Constitutional  symptoms 
appear  on  the  evening  of  the  seventh  or  the  morning  of  the  eighth  day 
following  the  inoculation.  These  symptoms  resemble  the  onset  of  true 
smallpox  and  are  rigor,  headache,  vomiting,  and  fever.  The  local  erup- 
tion subsides  on  the  appearance  of  the  febrile  symptoms  but  at  the  same 
time  the  general  eruption  breaks  out.  The  crop  is  usually  discrete,  mod- 
erate in  number,  but  runs  the  usual  course  through  papule,  vesicle  and 
pustule  formation. 

While  inoculation  has  properly  fallen  into  disuse,  there  are  con- 
ceivable emergencies  in  which  the  practice  would  be  justified.  For 
example,  on  board  ship  or  on  an  island  or  isolated  place,  in  the  absence 
of  vaccine  virus.  Under  such  circumstances  it  would  be  essential  to 
inoculate  everybody  at  the  same  time. 

The  inoculation  of  smallpox  will  always  remain  for  the  student  of 
preventive  medicine  one  of  the  most  interesting  episodes  in  the  develop- 

*  The  practice  of  inoculation  had  been  published  in  England  as  early  as  1714 
by  Dr.  Timoni  of  Constantinople;  at  Venice  in  1715  by  Pylarini,  and  in  the 
same  year  in  London  by  Mr.  Kennedy,  a  surgeon  who  had  been  in  Turkey.  Its 
adoption  and  subsequent  diffusion,  however,  were  due  to  Lady  Marv  Wortley 
Montagu. 


SMALLPOX  AND  VACCINATION"  29 

ment  of  the  sanitary  sciences.  It  illustrates  in  the  clearest  manner 
some  of  the  fundamental  phenomena  of  infection,  susceptibility,  and 
immunity.  It  was  animal  experimentation  on  a  huge  scale,  the  like  of 
which  we  shall  never  see  repeated  on  man  as  the  subject  (Sedgwick).  It 
is  now  a  matter  of  regret  that  for  the  sake  of  science  better  advantage 
was  not  taken  of  the  data. 


PREVALENCE  OF  SMALLPOX 

It  is  very  difficult  for  us  now  to  realize  that  smallpox  was  once  much 
more  common  than  measles  and  much  more  fatal.  Many  of  those 
who  recovered  were  disfigured  for  life,  left  blind,  or  with  some  other 
serious  consequence  of  the  disease.  For  centuries  smallpox  was  one  of 
the  greatest  scourges.  It  depopulated  cities  and  exterminated  nations. 
In  Europe  alone,  where  its  ravages  were  comparatively  slight,  it  killed 
hundreds  of  thousands  yearly.  In  the  18th  century,  of  which  we  have 
the  best  records,  almost  everybody  had  it  before  he  grew  up.  Parents 
often  exposed  their  children  to  the  disease  in  order  to  be  through  with 
it,  just  as  they  now  sometimes  do  with  the  minor  contagious  diseases. 

Smallpox  was  formerly  a  disease  of  children.  It  was  called  "kinder- 
bldttern."  Since  vaccination  protects  the  child,  smallpox  has  now  be- 
come more  prevalent  among  adults. 

The  distinguished  mathematician,  Bernouille,  estimated  that  15,000,- 
000  people  died  of  smallpox  in  25  years  in  the  18th  century.  It  has 
been  estimated  that  60  million  people  died  of  smallpox  during  that 
century.  Haygarth  gives  an  account  of  a  smallpox  epidemic  in  Chester, 
England,  population  14,713.  At  the  termination  of  the  epidemic  there 
were  but  1,060  persons,  or  7  per  cent,  of  the  population,  who  had  never 
had  smallpox.  Many  similar  instances  are  cited  in  the  literature. 
The  French  physician  de  la  Condamine  (1754)  said  that  "every  tenth 
death  was  due  to  smallpox  and  that  one-fourth  of  mankind  was  either 
killed  by  it  or  crippled  or  disfigured  for  life."  Sarcone  (1782)  esti- 
mated the  number  of  persons  in  Italy  who  suffered  from  smallpox  as 
90  per  cent,  of  the  population. 

Smallpox  was  introduced  into  the  western  hemisphere  by  the  Span- 
iards about  15  years  after  the  discovery  of  America.  In  Mexico  within 
a  short  period  three  and  one-half  million  persons  are  said  to  have  died 
of  the  disease  (Chapman).  Catlin  (1841)  states  that  of  12,000,000 
American  Indians  6,000,000  fell  victims  to  smallpox.  In  Iceland,  in 
1707,  18,000  perished  out  of  a  population  of  50,000,  that  is,  smallpox 
killed  36  per  cent,  of  the  total  population  in  one  year. 

A  good  example  is  that  of  Boston  in  1752,  population  at  that  time 
15,684.  Of  this  number  5,998  had  previously  had  smallpox.  During 
the  epidemic  5,545  persons  contracted  the  disease  in  the  usual  manner, 


30  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

and  2,124  took  it  by  inoculation.  1,843  persons  escaped  from  the  town 
to  avoid  infection.  There  were,  therefore,  left  in  the  city  but  174 
persons  who  had  never  had  smallpox. 

Smallpox  is  still  as  serious  as  it  was  in  former  times.  Thus,  in 
five  years,  from  1893-1897,  346,520  persons  died  of  smallpox  in  sixteen 
countries.  Of  this  number  Russia  alone  lost  275,502.  These  figures  are 
the  more  terrible  when  it  is  realized  that  these  lives  might  have  been 
saved  by  the  use  of  a  simple  prophylactic  measure  within  reach  of  all. 


EPIDEMIOLOGY 

Few  of  the  acute  infectious  diseases  show  such  a  complete  inde- 
pendence of  conditions  such  as  race,  climate,  soil,  age,  sex,  and  occu- 
pation, sanitary  surroundings,  etc.,  as  does  smallpox.  It  thrives  wherever 
the  contagion  is  carried,  and  wherever  it  finds  susceptible  people.  Prob- 
ably no  one  is  naturally  immune.  The  susceptibility  of  an  unvaccinated 
population  varies,  because  a  smallpox  outbreak  leaves  so  many  immune. 
This  is  one  reason  why  the  disease  recurs  in  waves.  The  mortality 
varies  greatly  in  different  epidemics.  At  times  it  is  less  than  one  per 
cent. ;  it  frequently  reaches  thirty  per  cent,  and  over. 

In  1901-1903  the  mortality  in  the  United  States  was  as  low  as  2  per 
cent.,  and  following  that  0.5  per  cent.  These  differences  occurred  in 
the  prevaccination  era  as  well  as  now. 

The  epidemiology  of  smallpox  bears  no  relation  to  improved  sanita- 
tion, which  has  diminished  the  prevalence  of  tuberculosis,  typhoid, 
cholera,  and  has  practically  subdued  typhus  and  relapsing  fever.  It  is 
evident  that  general  sanitation  could  not  affect  contagious  diseases  like 
smallpox  and  measles.  Smallpox  spares  neither  high  nor  low,  the  rich 
nor  poor;  before  the  days  of  vaccination  it  counted  many  kings,  queens, 
and  princes  among  its  victims. 


MODES  OF  INFECTION 

We  are  still  ignorant  of  the  precise  mode  by  which  smallpox  is 
conveyed.  The  view  generally  held  is  that  the  infection  is  air-borne 
and  enters  the  system  through  the  respiratory  mucous  membrane.  It 
has  been  surmised  that  a  local  lesion  may  be  produced  in  this  favor- 
able soil,  the  so-called  "propustule,"  from  which  general  infection 
through  the  blood  takes  place.  The  blood  infection  is  marked  by  a  sharp 
onset  (the  initial  symptoms),  and  the  skin  eruption  is  embolic  in  char- 
acter. The  objection  to  this  view  is  that  a  careful  search  at  54  autopsies 
in  Boston  by  Councilman  and  his  colleagues  failed  to  find  such  a  pro- 
pustule. 


SMALLPOX  AND  VACCINATION  31 

It  is  known  that  the  Chinese  inoculate  the  disease  by  placing  a  crust 
from  the  eruption  in  the  nostrils,  but  the  disease  so  produced  resembles 
variola  inoculata. 

The  virus  of  smallpox  is  contained  in  the  skin  lesions.  Of  this  we 
have  experimental  evidence.  It  is  also  supposed  to  be  in  the  expired 
air.  This,  however,  has  never  been  experimentally  proved  and  is  doubt- 
ful. The  disease  is  contagious  before  the  eruption  appears.  It  is  even 
believed  to  be  communicable  during  the  period  of  incubation.  Smallpox 
has  always  been  taken  as  the  type  of  the  contagious  diseases;  the  con- 
tagion is  the  most  "volatile"  of  any  of  the  diseases  of  man  with  the  pos- 
sible exception  of  measles.  This  volatility,  however,  has  been  over- 
estimated, and,  while  probably  an  air-borne  infection,  the  radius  of  dan- 
ger is  contracted.  English  observers  have  long  taken  the  view  that 
smallpox  may  be  blown  for  great  distances,  and  they  attribute  the  preva- 
lence of  smallpox  to  the  windward  of  hospitals  as  an  indication  that  the 
virus  may  be  carried  down  the  wind.  My  experience  with  the  disease 
teaches  me  that  the  danger  from  such  a  source  is  practically  nil.  One 
may  safely  live  next  door  to  a  smallpox  hospital  that  is  well  screened 
and  properly  managed.  The  influence  of  flies  and  other  insects,  or  sur- 
reptitious visiting,  may  account  for  the  spread  of  this  disease  outside 
of  hospital  walls. 

In  addition  to  more  or  less  direct  contact,  smallpox  may  be  spread 
indirectly  in  a  great  variety  of  ways.  The  secretions  from  the  mouth 
and  nose  doubtless  contain  the  infection,  and,  while  suspicion  has  not 
particularly  fallen  upon  the  feces  and  urine,  it  is  probable  that  all  the 
secretions  and  excretions  from  the  body  may  be  infective  at  some  time 
throughout  the  disease,  or  during  convalescence.  Toys,  pencils,  spoons, 
cups,  towels,  handkerchiefs,  bedding,  and  objects  of  the  greatest  variety 
that  have  in  any  way  come  in  contact  with  the  patient  may  carry  the 
infection.  Under  favorable  circumstances  the  active  principle  may  prob- 
ably live  for  a  considerable  time  upon  fomites,  although  the  practical 
danger  from  this  source  is  not  very  great. 

Smallpox  is  not  usually  considered  an  insect-borne  disease,  but  it  is 
highly  probable  that  a  fly  lighting  upon  a  smallpox  patient  and  get- 
ting its  proboscis,  feet,  and  other  portions  of  its  body  smeared  with  the 
variolous  matter,  and  then  flying  to  a  susceptible  person,  could  thus 
readily  transmit  the  infection.  Other  insects  may  by  such  mechanical 
transfer  play  a  similar  role. 

RESISTANCE  OF  TEE  VIRUS 

It  is  generally,  and  doubtless  correctly,  assumed  that  the  active 
principle  of  variola  has  approximately  the  same  resistance  to  external 
conditions  as  vaccine  virus.     This  assumption  is  confirmed  by  experi- 


32 


DISEASES  HAVING  SPECIAL  PKOPHYLAXIS 


mental  evidence,  which  shows  that  the  virus  of  smallpox  is  somewhat 
more  readily  destroyed  than  the  virus  of  cowpox.  Scientific  data  con- 
cerning the  viability  of  variolous  matter  is  meager,  owing  to  the  fact 
that  this  question  can  only  be  settled  by  prolonged  and  repeated  experi- 
ments upon  monkeys.  Brinckerhoff  and  Tyzzer^  found  that  variolous 
virus  is  less  resistant  to  desiccation  than  vaccine  virus;  that  variolous 
virus  does  not  pass  a  Berkefeld  filter  and  is  attenuated  by  long  exposure 
to  60  per  cent,  glycerin.  Prolonged  action  of  glycerin  also  destroys 
vaccine  virus,  but  more  rapidly  at  37°  C.  than  in  the  cold;  if  kept  at 
from  — 5°  to  — 15°  C.  glycerinated  virus  may  remain  active  for  years. 
In  general  it  may  be  said  that  variolous  virus  is  killed  by  exposure 
to  ordinary  germicidal  substances,  both  liquid  and  gaseous,  in  the 
strengths  and  time  commonly  employed.  It  succumbs  in  fact  before 
the  average  non-spore-bearing  bacteria. 


TABLE  2- 


-DEATH-RATE  FROM  SMALLPOX  AMONG  VACCINATED  AND  UNVACCI- 
NATED  IN  VARIOUS  COUNTRIES* 


Places  and  Time  of  Observation 


France,  1816-1841 

Quebec,  1819-1820 

Philadelphia,  1825 

Canton  Vaud,  1825-1829 

Verona,  1828-1829 

Milan,  1830-1851 

Breslau,  1831-1833 

Wiirttemberg,  1831-1835 

Carniola,  1834-1835 

Vienna  Hospital,  1834 

Carinthia,  1834-1835 

Adriatic,  1835 

Lower  Austria,  1835 

Bohemia,  1835-1855 

Galicia,  1836 

Dalmatia,  1836 

London  Smallpox  Hospital,  1836-1856 .  .  . . 

Vienna  Hospital,  1837-1856 

Kiel,  1852-1853 

Wiirttemberg  (no  date) 

Malta  (no  date) 

Epidemiological  Society  Returns  (no  date) 


Total  No. 
of  Cases 
Observed 


16,397 

? 

140 
5,838 

909 
10,240 

220 
1,442 

442 

360 
1,626 
1,002 
2,287 
15,640 
1,059 

723 
9,000 
6,213 

218 
6,258 
7,570 
4,624 


Death-rate  per  100 
Cases 


Among 

the  Unvac- 

cinated 


16.125 

27 

60 

24 

46.66 

38.33 

53.8 

27.33 

16.25 

51.25 

14.5 

15.2 

25.8 

29.8 

23.5 

19.66 

35 

30 

32 

38.9 

21.07 

23 


Among 
the  Vac- 
cinated 


1 

1.66 

0 

2.16 

5.66 

7.66 

2.11 

7.1 

4.4 

12.5 
0.5 
2.8 

11.5 
5.16 
5.14 
8.25 
7 
5 
6 

3}^ 
4.2 
2.9 


*  Extract  from  papers  prepared  in  1857  by  Sir  John  Simon,  Medical  OflScer  of  the  General  Board 
of  Health  of  England,  and  at  that  time  laid  before  Parliament  with  reference  to  the  History  and  Prac- 
tice of  Vaccination.  Published  in  first  Report  of  the  Royal  Commission  on  Vaccination,  1889,  Appen- 
dix 1,  p.  74. 

^  "Studies  upon  Experimental  Variola  and  Vaccinia  in  Quadrumana,"  Jour. 
Med.  Research,  Vol.  XIV,  No.  2,  Jan.,  1906,  pp.  223-359. 


SMALLPOX  AND  VACCINATION  33 

There  is  an  exception  to  this  statement  in  the  case  of  carbolic  acid 
and  the  coal-tar  disinfectants.  MeClintock  and  Ferry  ^  have  shown  that 
such  germicides  as  carbolic  acid,  cresols,  and  the  like  do  not  destroy  the 
virulence  of  vaccine  virus  in  0.5  per  cent,  solutions  in  five  hours'  expo- 
sure. In  this  strength  and  time  almost  all  non-spore-bearing  bacteria 
would  be  destroyed.  The  inference  is  allowable  that  this  class  of  disin- 
fectants cannot  be  relied  upon  to  prevent  the  spread  of  smallpox. 


SMALLPOX  IN  THE  VACCINATED  AND  UNVACCINATED 

The  experience  of  over  one  hundred  years  offers  convincing  proof 
of  the  pronounced  difference  in  the  mortality  and  morbidity  from  small- 
pox in  the  vaccinated  and  the  un vaccinated.  The  table  on  page  33  from 
Schamberg  shows  that,  among  thousands  of  cases  of  smallpox  occurring 
in  cities  all  over  the  world,  the  mortality  from  smallpox  has  been  from 
five  to  sixteen  times  greater  among  the  unvaccinated  than  among  the 
vaccinated. 

In  countries  like  Germany,  Sweden,  Ireland,  Scotland,  and  England, 
where  vaccination  is  more  or  less  compulsory,  there  is  comparatively  little 
smallpox.  In  countries  like  Belgium,  Russia,  Austria,  and  Spain,  which 
have  no  compulsory  vaccination  laws,  smallpox  yearly  claims  many  vic- 
tims.   See  Table  1,  page  26. 

THE  RESULT  OF   VACCINATION  IN   GERMANY 

April  8th,  1874,  Germany  passed  a  general  compulsory  vaccination 
and  revaccination  law.  The  law  requires  the  vaccination  of  all  infants 
before  the  expiration  of  the  first  year  of  life,  and  a  second  vaccination 
at  the  age  of  twelve.  Since  this  law  went  into  effect  there  have  been 
no  epidemics  of  smallpox  in  Germany,  despite  the  fact  that  the  disease 
has  been  frequently  introduced  from  without.  In  1897  there  were  but 
8  deaths  from  smallpox  in  the  entire  German  empire^ — ^population  54,- 
000,000.  Since  then  long  periods  have  passed  without  a  single  death 
from  smallpox.  From  1901  to  1910  there  were  only  380  deaths  from 
smallpox  in  Germany;  during  the  same  period  there  were  4,286  deaths 
from  smallpox  in  England  and  Wales,  with  only  about  half  the  popula- 
tion of  Germany;  furthermore,  many  of  the  deaths  in  Germany  were 
in  foreigners.  Thus  in  1909,  out  of  26  deaths  from  smallpox,  13  were 
foreigners,  11  of  whom  were  Russians.  In  the  huge  German  army  there 
have  been  only  two  deaths  from  smallpox  since  1874.  One  of  these  was 
a  reservist  who  had  not  been  successfully  vaccinated.  Germany  has 
taught  the  world  how  to  utilize  Jenner's  great  demonstration. 

^Jour.  of  the  Amer.  Public  Health  Assn.,  June,  1911   (Vol.  I,  No.  6),  p.  418. 
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36  DISEASES  HAVING  SPECIAL  riiOriiYLAXIS 

ISOLATION  AND  DISINFECTION 

Isolation  and  disinfection  are  only  secondary  measnres  in  prevent- 
ing smallpox.    They  cannot  be  regarded  as  substitutes  for  vaccination. 

Isolation  should  be  carried  out  with  strictness  for  the  reason  that 
smallpox  is  one  of  the  most  contagious  of  the  communicable  infections. 
While  the  patient  should  be  isolated,  it  is  not  necessary  to  isolate  the 
hospital  by  banishing  it  to  an  inconvenient  or  undesirable  location. 
There  is,  in  fact,  no  good  reason  why  a  smallpox  hospital  should  not 
be  one  of  the  units  of  the  general  hospital  for  communicable  diseases. 
In  any  event,  there  is  no  danger  from  a  smallpox  hospital  situated  upon 
a  highroad  or  near  other  habitations,  provided  always  proper  precautions 
are  taken  to  prevent  the  spread  of  the  disease. 

The  smallpox  hospital  should  not  be  a  pesthouse,  but  should  be  as 
inviting  and  attractive  as  economic  conditions  Justify.  Smallpox,  should 
not  be  treated  in  the  home.  From  the  standpoint  of  prophylaxis  the 
hospital  is  the  logical  and  best  place  to  care  for  this  and  other  communi- 
cable infections.  If  smallpox  is  treated  in  the  home,  this  should  only  be 
permitted  if  skilled  nursing  and  trained  attendants  can  be  provided. 

The  room  in  which  the  smallpox  patient  is  isolated  should  be  simply 
furnished  to  facilitate  cleanliness  and  to  permit  purification.  It  must 
be  well  screened  and  free  from  insects  and  vermin  of  all  kinds.  The 
room  should  be  well  ventilated.  This  may  be  accomplished  by  an  open 
fireplace,  in  which  case  the  contagium,  if  contained  in  the  outgoing  air, 
is  burned  in  exit. 

The  nurse  attending  a  case  of  smallpox  should  also  be  segregated, 
and  all  visiting  should  be  strictly  interdicted.  A  separate  kitchen  should 
be  provided  and  care  should  be  taken  that  the  dishes  be  scalded  and 
remnants  of  food  burned. 

Bedding,  underwear,  towels,  and  other  objects  should  not  leave  the 
sick  room  unless  they  are  first  boiled,  steamed,  or  immersed  in  a  suitable 
germicidal  solution,  such  as  bichlorid  of  mercury,  1-1,000,  or  formalin, 
10  per  cent.    Carbolic  acid  should  not  be  trusted. 

For  terminal  disinfection  either  sulphur  dioxid  or  formaldehyde 
may  be  used.  Objects  particularly  contaminated  or  soon  to  be  used 
by  others  should  be  given  a  separate  and  special  disinfection.  Finally, 
the  room  should  be  thoroughly  cleansed,  aired,  and  sunned. 

The  patient  must  be  regarded  as  the  source  and  fountainhead  of 
the  infection,  and  measures  should  be  used  at  the  bedside  to  prevent 
the  surroundings  from  becoming  contaminated.  Cloths,  cotton,  and 
other  dressings  that  become  soiled  with  the  contents  of  the  vesicles  and 
pustules  after  they  break  should  be  burned.  The  urine  and  feces  may 
be  disinfected  with  chlorinated  lime.  The  sputum  and  discharges  from 
abscesses  should  be  collected  on  cheap  cloths  and  burned.     As  a  rule. 


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BABIES  39 

smallpox  patients  are  not  dismissed  from  quarantine  until  desquama- 
tion has  ceased.  This  may  be  favored  by  the  use  of  warm  baths  and  a 
generous  use  of  soap,  also  by  anointing  the  skin  with  vaselin  or  a  bland 
oil.  Special  attention  should  be  given  to  the  hair,  which  should  be  well 
shampooed;  to  the  interdigital  spaces,  and  the  fingernails,  as  well  as 
to  all  folds  of  the  skin,  before  the  patient  is  released. 

The  management  of  a  smallpox  epidemic  is  discussed  on. page  368. 

REFERENCES 

Jenner,  Edward  :  "An  Inquiry  into  the  Causes  and  Effects  of  the  Variolae 
Vaccinae,  a  Disease  Discovered  in  Some  of  the  Western  Counties  of 
England,  Particularly  Gloucestershire,  and  Known  by  the  Name  of 
the  Cowpox."    London,  1798. 

Brit.  Med.  Jour.,  May  23,  1896  (Jenner  Centenary  Number). 

Brit.  Med.  Jour.,  July  5,  1902  (Special  Vaccination  Number). 

Report  of  the  Royal  Commission  on  Vaccination.     1897. 

AcLAND,  T.  D. :  "Vaccinia  in  Man."  Allbutt  and  Eolleston's  "System  of 
Medicine,"  Vol.  II,  Part  I,  p.  665.     1912. 

CoPEMAN,  MoNCKTON  *.  ^Tathology  of  Vaccinia."  Allbutt  and  Rolleston's 
"System  of  Medicine,"  Vol.  II,  Part  I,  p.  746. 

Baron,  John  :  "The  Life  of  Edward  Jenner,  with  Illustrations  of  His  Doc- 
trines and  Selections  from  His  Correspondence."  Vols.  I  and  II,  Henry 
Colbum,  London,  1838. 

German  Empire.  Vaccination  Law  of  April  8,  1874.  Published  in  English. 
P.  Paul,  Berlin,  1904. 

ScKAMBERG,  J.  F. :  "Vaccination  and  Its  Relation  to  Animal  Experimenta- 
tion."   Defense  of  Research  Pamphlet,  No.  1.    Am.  Med.  Ass'n. 

RABIES 

Synonyms. — Hydrophobia;  Wasserscfieu,  Wuth,  ToUwuth  (Ger- 
man) ;  Lyssa  (Greek) ;  La  Rage  (French). 

Rabies  is  an  acute,  specific,  rapidly  fatal  infection  communicated 
from  a  rabid  animal  to  a  susceptible  animal,  usually  through  a  wound 
produced  by  biting.  Man  always  contracts  the  disease  from  some  lower 
animal,  usually  the  dog.  The  infective  agent  must  be  inoculated  into 
the  tissues;  the  virus  is  harmless  when  ingested,  provided  the  mucosa 
is  intact.  The  gastric  juice  has  a  pronounced  deleterious  effect  upon  the 
virus.  Rabies  may  be  regarded  as  a  wound  infection.  The  specific  prin- 
ciple is  contained  in  the  saliva  of  animals  suffering  with  the  disease. 
The  infection,  therefore,  may  be  conveyed  by  licking  provided  there  are 
fissures  or  open  wounds  in  the  skin.  It  is  also  possible  to  introduce  the 
virus  through  autopsy  accidents  and  other  unusual  ways,  but  commonly 
it  is  introduced  through  wounds  produced  by  the  teeth  of  a  rabid  animal. 

Reference:  "Facts  and  Problems  of  Rabies,"  Stimson,  Hyg.  Lab.  Bull.,  No. 
65,  U.  S.  P.  H.  &  M.  H.  S. 


40  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

Every  mammalian  animal  is  susceptible.  Even  birds  may  contract 
the  disease.  It  is  most  common  in  dogs,  but  it  also  occurs  frequently 
in  wolves,  jackals,  foxes,  and  hyenas.  Eabies  in  cats  is  comparatively 
rare.  Cattle,  sheep,  and  goats  are  infected  relatively  in  about  the  same 
degree.  It  is  less  common  in  horses.  Swine  contract  the  disease  less 
frequently  than  other  domestic  animals.  Skunks  may  contract  the 
disease  and  sometimes  transmit  it  to  man. 

Although  all  mammals  are  susceptible  to  rabies,  it  is  perpetuated  in 
civilized  communities  almost  exclusively  by  the  domestic  dog,  only  to  a 
small  extent  by  wild  animals  of  the  dog  family,  and  occasionally  by 
skunks,  cats,  etc.  Outbreaks  have  been  reported  under  unusual  circum- 
stances. Thus  Carini  ^  reports  an  epizootic  believed  to  be  rabies  caus- 
ing the  death  of  about  4,000  cattle  and  1,000  horses  in  Sao  Paulo, 
Brazil.  There  was  no  unusual  prevalence  of  rabies  in  dogs  at  the  time 
but  it  was  noticed  that  bats,  in  broad  daylight,  attacked  and  bit  the 
cattle,  and  Carini  suggests  that  bats  may  have  been  the  source  of  the 
extensive  epizootic.  The  animals  affected  all  died  after  a  few  days  and 
the  meat  and  hides  were  utilized  but  no  mishaps  have  been  known  to 
follow. 

Eabies  exists  practically  all  over  the  world.  It  has  never  been  in 
Australia,  and  has  not  been  known  in  Denmark,  Norway  and  Sweden  for 
more  than  fifty  years,  and  recently  it  has  been  practically  eradicated 
from  England.  It  is  most  common  in  France,  Belgium,  and  Russia. 
In  the  United  States  111  human  deaths  were  reported  in  1908.  In  the 
same  year  there  were  535  localities  in  which  rabid  animals  were  reported; 
in  1911  there  were  1,381  localities,  and  98  deaths  in  man.  In  1890 
the  United  States  census  reported  143  deaths  in  30  states,  and  in  1900 
but  23  deaths. 

Rabies  is  remarkable  on  account  of  its  high  mortality — practically 
100  per  cent.  After  symptoms  are  pronoimced  recovery  rarely  takes 
place.  Joseph  Koch  (1910),  however,  describes  an  abortive  rabies.  The 
disease  is  peculiar  in  several  other  particulars,  especially  the  period  of 
incubation,  which  is  more  variable  and  more  prolonged  than  that  of  any 
other  acute  infection. 

Rabies  is  commonly  supposed  to  prevail  only  during  the  hot  months, 
but  it  may  be  just  as  bad  in  cold  weather.  In  fact,  exposure  to  cold 
seems  to  increase  its  virulence.  More  cases  occur  from  April  to  Sep- 
tember than  from  October  to  March  in  this  climate,  because  dogs  run 
abroad  more  freely  at  this  season  of  the  year.  It  is  this  fact,  and  not 
the  temperature,  that  influences  the  prevalence  of  the  disease. 

Period  of  Incubation.— From  the  standpoint  of  prevention  it  is  for- 
tunate that  the  period  of  incubation  of  this  disease  is  prolonged.  This 
period  varies  from  14  days  to  a  year  or  more.     The  average  period  is 

^Ann.  de  I'Inst.  Pasteur,  Paris,  Nov.,  XXV,  11,  p.  785. 


EABIES  41 

as  follows:  Man,  40  days;  dogs,  21-40  days;  horses,  38-56  days;  cows, 
28-56  days;  pigs,  14-21  days;  goats  and  sheep,  21-28  days;  birds,  14-40 
days. 

The  period  of  incubation  depends  largely  upon  the  site  of  the  wound, 
the  relation  to  the  nerve,  the  amount  and  virulence  of  the  virus.  It 
requires  about  15  days,  counting  from  the  last  injection,  to  induce  an 
active  immunity  to  the  disease  by  means  of  the  Pasteur  preventive  treat- 
ment. There  is,  therefore,  usually  sufficient  time,  if  the  case  is  seen 
early,  to  prevent  the  development  of  symptoms. 

It  is  probable  that  the  prolonged  period  of  incubation  is  due  in  part 
to  the  fact  that,  although  the  living  principle  reaches  the  central  nervous 
system,  it  remains  dormant  until  favorable  conditions  permit  multipli- 
cation and  the  production  of  toxic  effects  (Joseph  Koch). 

Entrance  and  Exit  of  the  Virus. — ^The  active  principle  of  rabies 
occurs  principally  in  the  saliva  and  in  the  central  nervous  system.  It 
may  be  in  the  saliva  at  least  three  days  (possibly  eight)  before  the  ani- 
mal shows  symptoms  (Eoux  and  Nocard).  It  is,  therefore,  sufficient  to 
watch  a  dog  that  has  bitten  a  person  or  another  animal  for  ten  days. 
If  no  symptoms  of  rabies  appear  during  this  time  there  is  no  danger 
of  conveying  the  disease,  and  the  Pasteur  treatment  is  unnecessary. 

The  virus  may  also  be  found  in  the  adrenals,  the  tear  glands,  the 
vitreous  humor,  the  spermatic  fluid,  the  urine,  the  lymph,  the  milk,  as 
well  as  all  parts  of  the  central  nervous  system  and  the  peripheral  nerves. 
It  is  also  found  in  the  spinal  and  ventricular  fluids.  It  has  not  been 
demonstrated  in  the  liver,  spleen,  blood,  or  muscles. 

The  virus  enters  the  system  through  the  broken  skin  and  follows 
the  nerve  trunks  from  the  seat  of  injury  to  the  spinal  cord,  thence  to 
the  medulla  and  brain.  The  route  corresponds  to  that  of  tetanus  toxin. 
The  mode  of  invasion  of  the  virus  may  explain  why  pain,  throbbing, 
tingling,  numbness  and  other  nervous  disturbances  are  the  first  symp- 
toms to  occur  in  parts  of  the  body  that  have  received  the  virus.  It 
also  partly  explains  the  variable  period  of  incubation,  which  is  shorter 
in  wounds  of  the  face  than  in  wounds  of  the  extremities.  It  also  ex- 
plains why  the  disease  is  more  liable  to  occur  when  the  wounds  are  in 
parts  of  the  body  where  there  is  an  abundant  nerve  supply. 

Noguchi^  announces  that  he  has  succeeded  in  growing  the  virus, 
which  appear  in  cultures  as  granular  and  pleomorphic  chromatoid  bod- 
ies, some  of  which  are  surrounded  with  membranes.  Williams  ^  and 
Moon  ^  believe  they  have  evidence  of  growth  in  brain  tissue,  having  pro- 
duced rabies  in  animals  in  the  fifth  generation  or  transfer  of  such 
cultures. 

^Noguchi,  Jour.  Exp.  Med.,  1913,  XVII,  29. 

==  Williams,  Anna  Wessel;  Jour.  A.  M.  A.,  1913,  LXI,  17,  p.  1509. 

^Moon,  Jour.  Infect.  Dis.,  1913,  XIII,  232. 


42  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

The  Relative  Danger  of  Bites. — Wolf  bites  are  most  dangerous  on 
account  of  the  savage  character  of  the  wound,  and  the  virulence  of  the 
virus.  Cat  bites  come  next,  and  then  dog  bites.  The  relative  danger 
of  bites  of  other  animals  is  as  follows :  foxes,  jackals,  horses,  asses,  cattle, 
sheep,  pigs.  There  is  no  authentic  instance  of  the  transmission  of  the 
disease  by  the  bite  of  man,  though  this  may  be  possible.  The  bites  of 
horses  and  other  herbivora  are  less  dangerous  because  their  blunt  teeth 
usually  cause  contused  wounds  without  breaking  the  skin. 

Bites  on  exposed  surfaces  are  more  dangerous  than  through  the 
clothing,  because  the  saliva  is  wiped  from  the  teeth  and  little  or  none 
enters  the  wound.  Long-haired  dogs  and  sheep  often  escape  infection 
for  the  same  reason.  Bites  upon  the  face  are  most  apt  to  be  followed 
by  rabies. 

Not  every  person  bitten  by  a  mad  animal  develops  rabies.  Leblanc's 
figures  are  16.6  per  cent.  The  statistics  are  difficult  to  analyze,  and  it 
is  almost  impossible  now  to  collect  sufficient  data.  According  to  the 
most  reliable  figures,  it  would  seem  that  rabies  develops  in  not  less  than 
one  person  in  ten  bitten  by  mad  dogs,  and  not  receiving  the  Pasteur 
treatment.    Paltauf  places  the  figures  at  6  to  9  per  cent. 

Viability. — The  virus  of  rabies  in  the  spinal  cord  of  rabbits  dies  in 
about  14  days  when  dried  at  20°-22°  C,  if  protected  from  putrefaction 
and  light.  Spread  in  thin  layers,  it  dies  in  4  or  5  days,  and  exposed 
to  the  sunlight  in  40  hours.  It  is  quite  resistant  to  putrefaction.  In 
a  decomposed  carcass  it  may  be  recovered  by  placing  some  of  the  central 
nervous  system  in  glycerin.  The  glycerin  destroys  most  of  the  con- 
taminating bacteria,  but  preserves  the  virus.  Eabic  virus  is  completely 
destroyed  at  50°  C.  in  one  hour,  and  at  60°  C.  in  30  minutes.  It  is 
not  injured  by  extreme  cold. 

Harris  found  the  virus  to  be  very  resistant  to  dryness  at  low  tem- 
peratures. Eabic  virus  in  central  nervous  tissue  is  very  resistant  to 
ordinary  germicides.  Sawtschence  ^  found  that  it  requires  from  five  to 
seven  days  to  destroy  the  fixed  virus  in  5  per  cent,  phenol,  and  that  it 
is  not  destroyed  by  0,5  per  cent,  phenol  in  20  days.  Semple  ^  found  that 
the  emulsion  of  fixed  virus  which  resists  the  action  of  1  per  cent,  phenol 
at  room  temperature  for  several  days,  succumbs  in  24  hours  at  37°  C. 
According  to  Cummings  ^  1  per  cent,  phenol  does  not  destroy  the  virus 
in  6  hours,  while  2  per  cent,  solution  kills  it  in  less  than  24  hours.  On 
the  other  hand,  most  of  the  aldehyd  compounds  are  very  active  in  de- 
stroying the  infectivity  of  the  fixed  virus.  A  0.5  per  cent,  solution  of 
salicylaldehyd,  benzaldehyd,  or  furfurol  destroys  the  virus  in  less  than 
3  hours.    The  specific  disinfecting  action  of  f ormaldehyd  is  shown  by  the 

1  Sawtschence,  W.,  Ann.  de  I'lnst.  Pastev/r,  1911,  XXI,  p.  492. 
*  Semple,  "Sci.  Mem.  by  Officers  of  Med.  and  San.  Depts.,"  Gov.  Ind.,  N.  S., 
No.  44. 

^Jour.  Infect.  Dis.,  XIV,  1,  January,  1914,  p.  33. 


EABIES 


43 


fact  that  the  virus  is  destroyed  when  exposed  for  two  hours  to  0.08 
per  cent,  solution.  This  indicates  that  formalin  may  be  a  useful  sub- 
stance to  treat  dog  bites,  although  experiments  have  shown  that  it  is 
not  as  dependable  as  nitric  acid.  Bichlorid  of  mercury,  1-1,000,  for 
1  hour,  or  a  saturated  solution  of  iodin  in  water,  completely  destroys  the 
virulence,  and  Wyrsykowski  has  shown  that  gastric  juice  has  a  pro- 
nounced deleterious  effect  upon  the  virus. 

PROPHYLAXIS 

The  prevention  of  rabies  is  considered  under  three  heads:  (1) 
Treatment  of  the  wounds;  (2)  the  Pasteur  prophylactic  treatment,  and 
(3)  the  control  of  the  disease  in  dogs  by  muzzling  and  quarantine. 

The  cauteriz'ation  of  the  wound  and  the  Pasteur  prophylactic  treat- 
ment are  efficient  preventive  measures  for  the  individual,  but  they  are 
not  the  true  and  best  methods  of  controlling  and  preventing  rabies. 


Fig.  11.     Chart  Showing  Relation  of  Enforcement  of  Muzzling  Law  to  Prev- 
alence OF  Rabies  in  Great  Britain. 

The  figures  in  the  cross-patching  indicate  the  number  of  persons  who  died  of  rabies_in 
England  and  Wales.     The  ordinates  represent  cases  in  dogs.     (Frothingham.) 

The  disease  may  be  avoided,  even  exterminated,  by  an  intelligent  system 
of  muzzling  and  quarantining  of  dogs.  A  high  tax  on  dogs  and  leash- 
ing are  only  restrictive  measures.  In  England,  when  the  dogs  were 
muzzled,  rabies  diminished.  The  law  was  repealed,  owing  to  misplaced 
sympathy  for  the  dog,  and  rabies  promptly  increased.  The  law  was 
again  enforced,  and  in  about  two  years  the  disease  disappeared  (see  Fig. 


44  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

11).  Now  a  strict  quarantine  of  six  months  is  maintained  against 
dogs  entering  England.  It  is  no  longer  necessary  to  muzzle  dogs  in 
England,  but  muzzles  will  again  be  required  should  the  disease  reappear. 
Consistent  muzzling  of  all  dogs  for  two  years  will  practically  exterminate 
rabies.  In  Australia  there  are  few  carnivorous  animals,  mostly  marsu- 
pials ;  there  rabies  does  not  exist,  for  it  has  been  kept  out  owing  to  early 
and  effective  quarantine  measures.  Norway,  Sweden,  and  Denmark  show 
good  results  and  the  same  can  be  done  in  other  peninsular  regions. 

Prophylactic  measures  necessary  to  control  the  dog  question  are : 
the  destruction  of  ownerless  dogs;  license  fee  and  tag  for  all  dogs; 
owners  to  be  legally  responsible  for  damage  inflicted  by  their  dogs; 
education  of  the  dog-owning  public  concerning  the  spread  of  communi- 
cable diseases,  especially  rabies;  compulsory  reporting'  of-  all  cases  or 
suspected  cases  of  rabies.  Further  special  and  temporary  measures 
advocated  are :  muzzling ;  restraint  with  chains,  leash,  etc. ;  observation 
in  quarantine,  or  killing  of  all  animals  bitten  by  dogs ;  disinfection,  etc.^ 


THE  LOCAL  TEEATMENT  OF  THE  WOUND 

Wounds  produced  by  the  bite  of  an  animal  in  which  there  is  any 
suspicion  of  rabies  should  at  once  be  cauterized  with  "fuming"  or  strong 
nitric  acid.  The  acid  is  best  applied  with  a  glass  rod  very  thoroughly  to 
all  the  parts  of  the  wound,  care  being  taken  that  pockets  and  recesses  do 
not  escape.  Thorough  cauterization  at  once  reduces  the  danger  of  wound 
complications,  and  experience  demonstrates  that  wounds  so  treated  at 
once  are  practically  never  followed  by  rabies.  Marie  obtained  conflicting 
results  with  local  treatment  in  experimental  rabies ;  Cabot  ^  obtained  the 
best  results  in  a  series  of  extensive  experiments  with  nitric  acid,  and 
was  able  to  save  the  lives  of  91  per  cent,  of  guinea-pigs  by  cauterization 
with  nitric  acid  at  the  end  of  24  hours ;  Poor  ^  saved  45  per  cent.,  at  the 
end  of  23  hours.  In  the  absence  of  nitric  acid  formalin  or  the  actual 
cautery  may  be  used.  Strong  antiseptics,  such  as  carbolic  acid,  are  not 
reliable.  Nitrate  of  silver  is  valueless.  In  any  wound  produced  by  the 
bite  of  an  animal  cauterize  unless  sure  that  the  animal  is  not  mad. 

It  has  been  shown  that  the  virus  may  remain  alive  and  virulent  in 
the  scar  for  a  long  time,  and  it  has  become  a  question  whether  patients 
seen  after  the  wound  has  healed  should  not  have  the  scar  excised  and  the 
wound  cauterized  with  nitric  acid ;  this,  however,  is  not  done  now. . 

1  In  addition  to  rabies,  dogs  are  responsible  for  other  infections,  such  as 
hydatis,  tapeworms  (especially  in  children),  round  worms,  tongue  worms,  and 
also  fleas  and  ticks  which  transfer  from  the  dog  to  man  and  which  may  in  this 
way  transmit  diseases  and  parasites. 

""  Medical  News,  March,  1899. 

^  Collected  Studies,  Research  Lab.,  Dept.  of  Health,  City  of  N.  Y.,  VI. 
1911,  p.  25. 


EABIES  45 

THE  PASTEUR  PROPHYLACTIC  TREATMENT 

This  method  of  prophylaxis  was  announced  December  6,  1883,  by 
Pasteur,  at  the  International  Congress  at  Copenhagen,  and  on  February 
24,  1884,  he  laid  before  the  French  Academy  the  details  of  his  experi- 
ments and  results.  The  next  year  Pasteur,  with  the  help  of  Eoux  and 
Chamberland,  worked  out  the  details  of  the  method  now  in  general  use. 

The  principle  of  the  treatment  consists  in  producing  an  active  im- 
munity by  means  of  an  attenuated  virus.  The  virus  is  attenuated  by 
drying.  The  fixed  virus  contained  in  the  spinal  cord  of  rabbits  dead  of 
hydrophobia  is  the  material  used,  for  subcutaneous  injection. 

Street  Virus  and  Fixed  Virus. — The  distinction  between  fixed  and 
street  virus  is  of  fundamental  importance  in  reference  to  the  question 
of  immunity.  Street  virus  refers  to  the  virus  obtained  from  mad  dogs 
naturally  infected.  When  this  virus  is  inoculated  into  a  rabbit,  it  re- 
produces the  disease  after  a  period  of  incubation  of  from  14  to  21 
days  or  more.  This  street  virus  may  then  be  conveyed  from  rabbit  to 
rabbit  through  a  number  of  transfers.  In  the  passage  from  rabbit  to 
rabbit  the  virus  becomes  more  virulent  for  rabbits.  The  period  of  incu- 
bation is  progressively  shortened,  until  finally  the  rabbits  invariably 
sicken  on  the  sixth  or  seventh  day  and  die  on  the  ninth  or  tenth.  When 
the  virus  has  reached  this  degree  of  virulence  for  rabbits,  it  is  said  to  be 
''fixed,"  for  the  reason  that  its  potency  remains  constant.  In  its  pas- 
sage through  rabbits  the  modification  from  street  virus  to  fixed  virus  is 
gradual.  It  is  important  to  note  that  fixed  virus,  which  has  attained  a 
high  degree  of  virulence  for  rabbits,  has  lost  much  of  its  virulence  for 
dogs,  and  is  probably  a  virulent  for  man. 

Proescher  ^  injected  into  himself  the  entire  brain  and  medulla  of 
a  rabbit  (fixed  virus),  and  another  entire  brain  into  a  volunteer.  No 
ill  effects  of  any  kind  were  noted  in  either  case.  A  control  rabbit  in- 
jected with  a  0.02  dilution  of  the  same  emulsion  died  in  seven  days  with 
experimental  rabies. 

Marx  tested  the  fresh  fixed  virus  upon  monkeys  in  large  doses,  with 
negative  results.  Ferran  in  Barcelona  in  1887  inoculated  85  persons 
with  the  fresh  fixed  virus  as  a  prophylactic  treatment  for  dog  bites 
with  good  results,  which  have  been  further  confirmed  by  Wysokowiez 
and  ISTitsch.  The  evidence  points  clearly  to  the  fact  that  the  fixed  virus 
of  rabbits  does  not  produce  rabies  in  man  when  introduced  into  the,  sub- 
cutaneous tissue. 

Preparation  of  the  Virus. — Eabbits  are  injected  under  the  dura 
mater  with  a  few  drops  of  an  emulsion  of  fresh  fixed  virus  obtained 
from  the  pons  or  medulla  of  another  rabbit  dead  of  hydrophobia.     Strict 

^N.  Y.  Med.  Jour.,  Oct.  9,  1909,  also  Arch,  of  Int.  Med.,  Sept.,  1911,  VIII, 
3,  p.  353. 


46  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

aseptic  precautions  are  necessary  in  order  to  keep  out  other  infections. 
The  rabbit  should  begin  to  show  symptoms  on  the  sixth  or  seventh  day, 
and  die  on  the  ninth  or  tenth.  Usually  the  rabbit  is  not  allowed  to 
die,  but  is  chloroformed  on  the  last  day  in  order  to  avoid  terminal 
infections  and  unnecessary  suffering.  The  spinal  cord  is  removed  and 
hung  in  a  bottle  containing  potassium  hydroxid.  These  bottles  are 
kept  in  the  dark  at  a  temperature  of  20°-22°  C.  Under  these  conditions 
the  cord  gradually  desiccates,  and  at  the  same  time  the  virulence  of 
the  virus  diminishes,  until  the  fourteenth  day,  when  it  is  no  longer 
infective.  This  is  why  Pasteur  started  the  treatment  with  a  cord  four- 
teen days  old. 

One-half  a  cubic  centimeter  of  the  cord  constitutes  a  dose.  This  is 
ground  in  sterile  salt  solution  so  as  to  produce  a  uniform  emulsion,  which 
is  injected  into  the  subcutaneous  tissue  of  the  abdominal  wall.  In  many 
institutes  the  small  segments  cut  each  day  from  the  drying  cord  are 
placed  in  pure  glycerin.  The  virulence  of  the  cord  in  glycerin  is  not 
altered  for  at  least  30  days,  if  kept  in  the  dark  and  at  15°  C.  This 
method,  introduced  by  Calmette^  in  1891,  based  upon  observation  made 
by  Hons  in  1887,^  is  very  convenient,  especially  where  comparatively 
few  patients  are  treated.  Glycerin  has  the  added  advantage  of  destroy- 
ing infections  due  to  non-spore-bearing  bacteria  that  may  be  present. 

As  a  further  precaution,  bacteriological  examinations  are  made  of 
parts  of  the  spinal  cord  in  order  to  insure  the  absence  of  bacteria,  and 
the  rabbit  is  carefully  autopsied  as  a  guarantee  that  no  other  disease  is 
present. 

It  is  no  longer  necessary  for  persons  to  go  to  a  Pasteur  Institute 
for  the  treatment;  the  emulsion  may  be  sent  through  the  mail  in  a 
thermos  bottle,  or  small  segments  of  cord  may  be  shipped  in  glycerin. 

The  scheme  of  treatment  advocated  by  Pasteur  and  still  used  at 
I'Institut  Pasteur  in  Paris  and  many  other  places  is  shown  on  page  47. 

Many  Pasteur  institutes  now  use  a  modified  treatment,  starting  with 
an  8-day  instead  of  a  14-day-old  cord,  which  is  exemplified  in  the  scheme 
used  at  the  Hygienic  Laboratory,  Public  Health  Service,  table,  page  48. 

The  scheme  of  Pasteur  has  been  further  modified  in  various  ways, 
depending  upon  the  method  used  to  attenuate  the  virus.  Thus  Pasteur 
attenuated  the  virus  by  drying;  Babes  by  heating;  Frantzer  by  the  use 
of  bile ;  Tizzoni  and  Cattani  attenuated  the  virus  in  gastric  juice.  Hoy- 
ges  used  fresh  material  in  a  diluted  suspension;  Ferran  fresh  material 
and  in  increasing  doses.  Gumming  altered  the  virus  by  dialysis.  Harris 
dried  the  fresh  virus  at  low  temperature,  which  is  used  in  diluted  sus- 
pension. Other  methods  have  been  used  to  attenuate  the  virus,  such  as 
glycerin,  carbolic  acid,  mechanical  disintegration,  and,  lastly,  antirabic 

^Ann.  de  I'lnst.  Pasteur,  Paris,  1891,  Vol.  V,  p.  633. 

"Ann.  de  I'Inst.  Pasteur,  Paris,  1887,  Vol.  I,  p.  87. 


E  ABIES  47 

PASTEUR  PROPHYLACTIC  TREATMENT— RECOMMENDED  BY  PASTEUR 


Mild  Treatment 

Intensive  Treatment 

Amount  of 

Amount  of 

Day                  t 
of                 th 

Lge  of 
e  Dried 

Injected 
Emulsion 

Day 
of 

Age  of 
the  Dried 

Injected 
Emulsion 

^  Treatment 

Cord 

1  cm.  to  5  c.  c. 

Treatment 

Cord 

1  cm.  to  5  c.  c. 

14  Days 

3  c.  c. 

^                     \ 

'  14  Days 

3  c.  c. 

1 

13 

3 

,  13 

3 

1  ^^ 

3 

11 

3 

[10 

3 

2                     1 

ri2 

3 

2 

^ 

3 

111 

3 

8 

3 

7 

3 

f  10 

3 

/    6 

2 

3                    i 

I  9 

3 

3 

\    6 

2 

f     8 

3 

4 

5 

2 

4                     -! 

\    '^ 

3 

J 

^    6 

2 

5 

5 

2 

^                     1 

I    6 

2 

6 

5 

2 

6 

4 

2 

7 

5 

2 

7 

3 

1 

8 

4 

2 

8 

4 

2 

9 

3 

1 

9 

3 

1 

10 

5 

2 

10 

5 

2 

11 

5 

2 

11 

5 

2 

12 

4 

2 

12 

4 

2 

13 

4 

2 

13 

4 

2 

14 

3 

2 

14 

3 

2 

15 

3 

2 

15 

3 

2 

16 

5 

2 

16 

5 

2 

17 

4 

2 

17 

4 

2 

18 

3 

2 

18 

3 

2 

19 

5 

2 

20 

4 

2 

21 

3 

2 

serum.  Ferran  in  Barcelona,  Proescher  in  Pittsburgh,  and  others  in- 
ject patients  with  the  unaltered,  fresh,  fixed  virus.  The  advantages 
of  using  the  virus  as  fresh  and  strong  as  possible  are  that  an  active  im- 
munity is  produced  more  quickly,  and  this  is  of  considerable  importance 
in  wounds  of  the  face;  also  in  wolf  and  cat  bites,  which  frequently 
have  a  short  period  of  incubation.  Further,  only  one  or  two  injections 
of  the  fresh  virus  are  necessary  to  produce  an  immunity,  and  this 
shortens  and  simplifies  the  treatment  very  much. 

Harris  ^  has  shown  that  rabic  material  may  be  completely  desiccated 
without  destruction  of  virulence,  provided  the  dehydration  takes  place 
at  a  low  temperature.  The  lower  the  temperature  the  greater  will  be 
the  amount  of  virulence  preserved.  Virus  so  desiccated  contains  per 
weight  as  much  infectivity  as  the  fresh  virus.     The  virus  thus  dried  is 

^Jour.  of  Infect.  Dis.,  May,  1912,  X,  3,  pp.  369-377. 


48 


DISEASES  HAVING  SPECIAL  PROPHYLAXIS 


PASTEUR   PROPHYLACTIC   TREATMENT— HYGIENIC  LABORATORY,  WASHINGTON, 

D.  C. 


Amount 

Ago  of  the  Dried 
Cord 

Day 

Adult 

5  to  10  Years 

1  to  5  Years 

Scheme  for  Mild  Treatment 

1 

8-7-6 

2.5  c.  c. 

2.5c.  c. 

2.0  c.  c. 

2 

5-4 

2.5 

2.5 

1.5 

3 

4-3 

2.5 

2.5 

2.0 

4 

5 

2.5 

2.5 

2.5 

5 

4 

2.5 

2.5 

2.5 

6 

3 

2.5 

2.5 

2.0 

7 

3 

2.5 

2.5 

2.0 

8 

2 

2.5 

1.5 

1.0 

9 

2 

2.5 

2.0 

1.5 

10 

5 

2.5 

2.5 

2.5 

11 

5 

2.5 

2.5 

2.5 

12 

4 

2.5 

2.5 

2.5 

13 

4 

2.5 

2.5 

2.5 

14 

3 

2.5 

2.5 

2.0 

15 

3 

2.5 

2.5 

2.0 

16 

2 

2.5 

2.0 

1.5 

17 

2 

2.5 

2.0 

1.5 

18 

4 

2.5 

2.5 

2.5 

19 

3 

2.5 

2.5 

2.5 

20 

2 

2.5 

2.5 

2.0 

21 

2 

2.5 

2.5 

2.0 

Scheme  for  Intensive  Treatmer.t 

1 

8-7-6 

2.5  c.  c. 

2.5  c.  c. 

2.5  c.  c. 

2 

4-3 

2.5 

2.5 

2.0 

3 

6-4 

2.5 

2.5 

2.5 

4 

3 

2.5 

2.5 

2.0 

5 

3 

2.5 

2.5 

2.0 

6 

2 

2.5 

2.0 

1.5 

7 

2 

2.5 

2.5 

2.0 

8 

1 

2.5 

1.5 

1.0 

9 

5 

2.5 

2.5 

2.5 

10 

4 

2.5 

2.5 

2.5 

11 

4 

2.5 

2.5 

2.5 

12 

3 

2.5 

2.5 

2.0 

13 

3 

2.5 

2.5 

2.0 

14 

2 

2.5 

2.5 

2.0 

15 

2 

2.5 

2.5 

2.0 

16 

4 

2.5 

2.5 

2.5 

17 

3 

2.5 

2.5 

2.5 

18 

2 

2.5 

2.5 

2.0 

19 

2 

2.5 

2.5 

2.0 

20 

3 

2.5 

2.5 

2.5 

21 

2 

2.5 

2.5 

2.0 

SO  stable  that  it  may  be  standardized,  permitting  an  accuracy  of  dosage 
hitherto  impossible.  The  unit  is  the  smallest  amount  which,  when 
injected  intracerebrally  into  a  full-grown  rabbit,  will  produce  paresis 


RABIES  49 

on  the  seventh  day.  The  use  of  this  desiccated  virus  in  the  prophylactic 
immunization  of  animals  and  persons  offers  many  advantages  over  other 
methods  and  is  gradually  coming  into  use. 

Treatment  at  a  distance  from  a  Pasteur  institute  is  now  practical 
by  sending  a  piece  of  cord,  or  the  emulsion  in  glycerin,  or  the  dry  mate- 
rial in  accordance  with  Harris'  method. 

Care  During  the  Treatment. — During  the  treatment  the  patient 
may  go  about  his  usual  business.  It  is  not  necessary  to  stay  in  bed. 
The  patient  should,  however,  avoid  fatigue,  cold,  emotional  stress, 
trauma,  and  alcohol.  It  has  been  shown  that  these  are  important  pre- 
disposing factors  to  the  disease.  It  was  found  that  customs'  officers  re- 
turning to  the  Siberian  borders  after  prophylactic  treatment  for  wolf 
bites  showed  an  unusual  mortality,  which  seemed  to  be  due  to  exposure 
to  cold.  The  disease  has  been  observed  to  be  brought  on  after  a  cold 
bath,  falling  into  the  water,  and  similar  depressing  influences. 

Complications  of  the  Treatment. — The  Pasteur  prophylactic  treat- 
ment may  be  complicated  by  (1)  local  reactions  or  (3)  paralysis. 

Local  reactions  at  the  site  of  the  wound  are  usually  trivial.  Ab- 
scesses, almost  never  occur.  The  local  reactions  consist  of  redness  and 
induration.  It  is  not  necessarily  the  last  injection,  but  rather  the  site 
of  some  previous  injection  that  flares  up.  They  soon  subside  without 
further  trouble.  This  occurrence  increases  with  the  progress  of  the 
treatment;  it  is  most  frequent  in  the  second  week.  As  the  treatment 
involves  the  introduction  of  a  large  quantity  of  foreign  proteins  into 
the  body,  it  is  probable  that  these  reactions  represent  a  phase  of  hyper- 
susceptibility.     (See  Anaphylaxis.) 

Paralysis. — Paralysis  occasionally  occurs  and  may  be  fatal.  There 
is  doubt  concerning  the  cause  of  this  paralysis,  and  a  question  whether 
it  may  be  a  mild  or  modifled  type  of  rabies,  or  a  form  of  anaphylaxis. 
In  a  case  treated  at  the  Hygienic  Laboratory  the  paralysis  came  on  18 
days  after  treatment,  and  was  transient.  H.  E.  Hazeltine  ( Public  Health 
Eeport,  July  30,  1915,  Vol.  XXX,  No.  31,  p.  2227)  reports  two  cases  of 
paralysis  following  antirabic  treatment,  with  one  death.  The  New  York 
Pasteur  Institute  reports  a  death  from  "ascending  paralysis,"  which 
came  on  four  days  after  the  treatment.  W.  A.  Jones  ^  reported  two 
cases  with  recovery.  In  1905  Remlinger,  head  of  the  Constantinople 
Institute  for  Rabies,  reported  40  cases  of  paralysis;  Miiller  found  16 
cases  in  the  literature,  and  had  two  of  his  own;  Panpoukis,  three  cases; 
Jones,  2 ;  making  a  total  of  63,  2  of  whom  died. 

The  Immunity. — Duration. — The  immunity  appears  two  weeks  after 

the  treatment  and  lasts  a  varying  period  of  time,  depending  upon  the 

individual — at  least  for  several  years.     In  this  respect  it  does  not  differ 

from  other  instances  of  acquired  immunity.    The  fact  that  the  immunity 

Vow,  A.  M.  A.,  Nov.  13,  1909,  p.  1626. 


50  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

appears  on  about  the  fifteenth  day  after  the  end  of  the  treatment  was 
discovered  by  Pasteur  as  a  result  of  animal  experimentation.  The  sta- 
tistics of  the  Pasteur  Institute,  giving  the  mortality  from  rabies  in 
persons  following  the  prophylactic  treatment,  exclude  instances  in  which 
the  disease  develops  within  fifteen  days  after  the  last  prophylactic 
injection. 

Nature. — 'The  nature  of  the  immunity  is  not  clear.  It  certainly 
is  not  due  to  an  antitoxin.  Immune  bodies  are  demonstrable  in  the 
blood  twenty  days  after  the  last  injection.  This  is  determined  by  mixing 
in  vitro  the  active  virus  with  the  blood  serum,  which  neutralizes  its 
activity.  This  neutralization  is  generally  considered  to  be  microbicidal 
or  lytic  in  nature. 

Degree. — The  degree  of  the  immunity  also  varies,  as  is  evidenced 
by  the  fact  that  a  certain  small  percentage  of  the  persons  treated  die 
of  rabies. 

The  Results  of  the  Treatment. — Statistics  giving  the  results  of  the 
treatment  are  somewhat  difficult  to  analyze,  as  many  factors  are  unob- 
tainable. Patients  should  be  kept  under  observation  at  least  a  year. 
Exceptional  cases  occur  one  year  following  the  treatment.  Cases  that 
occur  within  fifteen  days  after  the  treatment  are  excluded  from  the 
French  statistics,  for  reasons  that  have  already  been  stated.  The  figures 
on  this  basis  show  a  mortality  of  less  than  0.5  per  cent.  Better  results 
are  being  obtained  from  year  to  year. 

The  table  on  page  51  gives  the  general  results  at  I'Institut  Pasteur, 
Paris,  since  beginning  the  treatment. 

When  we  compare  these  figures  with  the  fact  that  from  6  to  10  per 
cent,  and  sometimes  16.6  per  cent,  of  all  persons  bitten  by  rabid  dogs 
die  of  rabies,  the  prophylactic  value  of  the  Pasteur  treatment  is  evident 

Some  series  of  cases  give  a  much  higher  mortality.  Thus,  of  855 
persons  bitten  by  mad  dogs,  collected  by  Tardieu,  Thamehayn,  and 
Bouley,  399  ended  in  death,  or  46.6  per  cent.  In  another  series  of 
cases  given  by  Bouley,  out  of  366  persons  bitten  by  mad  dogs,  152  died 
of  hydrophobia.  But  of  these  120  were  bitten  on  the  face  and  hands, 
the  greater  danger  of  which  has  been  mentioned.  The  mortality  of 
bites  from  wolves  is  placed  at  from  60  to  80  per  cent. 

Contraindications. — There  are  no  particular  contraindications  to  the 
treatment.  All  ages  and  conditions  should  be  treated  if  exposed.  Ap- 
parently no  harm  is  done  pregnant  women.  I  have  injected  patients 
having  malaria  without  trouble  following.  The  treatment  may  be  con- 
tinued in  patients  having  colds,  fevers,  and  other  ailments  without  no- 
ticeable harm. 

Wh.en  to  Give  the  Pasteur  Prophylactic. — It  is  sometimes  difficult  to 
decide  whether  the  Pasteur  prophylactic  treatment  should  or  should 
not  be  given.     The  treatment  causes  sufficient  personal  inconvenience, 


EABIES 

RESULTS  OF  TREATMENT  AT  L'INSTITUT  PASTEUR.  PARIS. 


51 


Year 

Percons 

Deaths 

Mortality 

1886 

2,671 

25 

0.94% 

1887 

1,770 

14 

0.79 

1888 

1,622 

9 

0.55 

1889 

1,830 

7 

0.38 

1890 

1,540 

5 

0.32 

1891 

1,559 

4 

0.25 

1892 

1,790 

4 

0.22 

1893 

1,648 

6 

0.36 

1894 

1,387 

7 

0.50 

1895 

1,520 

5 

0.38 

1896 

1,308 

4 

0.30 

1897 

1,521 

6 

0.39 

1898 

[1,465 

3 

0.20 

1899 

1,614 

4 

0.25 

1900 

1,420 

4 

0.28 

1901 

1,321 

5 

0.38 

1902 

1,005 

2 

0.18 

1903 

628 

2 

0.32 

1904 

755 

3 

0.39 

1905 

727 

3 

0.41 

1906 

772 

1 

0.13 

1907 

786 

3 

0.38 

1908 

524 

1 

0.19 

1909 

467 

1 

0.21 

1910 

401 

0 

0.00 

1911 

341 

1 

0.29 

1912 

395 

0 

0.00 

1913 

330 

0 

0.00 

1914 

373 

0 

0.00 

not  to  speak  of  the  danger  (however  slight)  of  paralysis,  to  avoid  advis- 
ing it  if  unnecessary.  In  many  cases  it  is  impossible  to  discover  whether 
the  dog  that  inflicted  the  bite  is  mad  or  not.  The  rule  in  cases  of 
doubtful  exposure  is  to  advise  the  treatment. 

Persons  not  infrequently  apply  for  advice  giving  the  following  his- 
tory: They  have  not  been  bitten,  but  they  have  been  licked  on  the 
hands  and  face  by  a  dog  that  subsequently  developed  the  disease.  Per- 
sons are  sometimes  similarly  exposed  by  washing  the  mouth  of  a  rabid 
horse.  In  these  cases  the  important  question  is  whether  there  were 
fissures  or  abrasions  in  the  skin  at  the  time.  There  may  be  little 
wounds  in  the  skin  not  evident  to  the  naked  eye.  In  such  cases  the 
danger  is  slight,  but  in  apprehensive  subjects  the  assurance  of  protection 
which  the  treatment  affords  is  an  important  element  in  arriving  at  a 
decision. 

In  all  cases  it  is  important  to  know  whether  the  dog  is  mad  or  not. 
If  the  dog  can  be  found  and  kept  under  observation  for  10  days  and 
no  symptoms  appear,  the  Pasteur  treatment  is  not  necessary.  Animals 
killed  early  in  the  course  of  rabies  may  fail  to  show  the  microscopic 


52  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

evidence  of  the  disease,  thus  causing  an  indcfnjitc  delay  in  diagnosis 
awaiting  inoculation  tests.  Should  the  dog  develop  symptoms,  the  ques- 
tion of  diagnosis  is  all-important. 

Diagnosis  of  Rabies  in  Dogs. — The  diagnosis  of  rallies  in  dogs  may 
be  made  in  four  ways:  (1)  from  the  symptoms;  (2)  from  the  presence 
of  Negri  bodies  in  the  central  nervous  system;  (3)  from  the  lesions 
in  the  peripheral  ganglia,  and  (4)  by  animal  inoculations. 

1.  The  symptoms  may  be  very  suggestive,  but  a  diagnosis  must 
always  rest  upon  the  pathological  lesions  and  the  inoculation  tests. 
The  course  of  the  disease  may  be  divided  into  three  stages :  a  premoni- 
tory stage,  a  stage  of  excitement,  and  a  paralytic  stage.  The  first 
two  stages  may  be  absent  or  transient.  All  rabid  animals  invariably 
become  paralyzed  before  they  die.  In  dogs  the  first  symptom  consists 
solely  in  a  change  in  the  disposition  of  the  animal.  He  is  easily  excited, 
but  does  not  show  a  disposition  to  bite.  Soon  the  restlessness  becomes 
more  marked,  and  the  animal  may  become  furious  and  even  show 
signs  of  delirium.  The  animal  does  not  fear  water,  as  is  commonly 
supposed,  but  rushes  about  attacking  every  object  in  his  way.  Dogs 
suffering  from  furious  rabies  have  a  tendency  to  run  long  distances 
(25  miles  or  more),  often  biting  and  inoculating  large  numbers  of  other 
animals  and  persons  en  route.  Very  soon  paralysis  sets  in,  commencing 
in  the  hind  legs,  and  finally  becomes  general.  The  course  of  the  disease 
is  always  rapid,  averaging  from  4  to  5  days,  rarely  exceeding  10  days. 
When  the  stage  of  excitement  is  brief  or  absent,  the  disease  is  known 
as  dumb  rabies. 

2.  There  is  a  difference  of  opinion  concerning  the  significance  of 
the  Negri  bodies  (Neuroryctes  hydrophobiae) ,  which,  however,  are  very 
constant  in  rabies  and  peculiar  to  it.  If  Negri  bodies  are  found  in  the 
dog,  the  Pasteur  treatment  should  be  started  at  once.  The  absence 
of  Negri  bodies,  however,  does  not  necessarily  mean  the  absence  of 
rabies.  These  bodies  are  sometimes  difficult  to  find,  or  may  not  be 
present  in  the  parts  of  the  central  nervous  system  which  are  examined. 
Negri  bodies  are  found  especially  in  the  horn  of  Ammon;  they  are 
1  to  23  micra  in  diameter ;  usually  round  or  oval ;  strongly  eosinophilic ; 
occur  within  and  without  the  nerve  cells;  and  sometimes  contain  a 
nucleus  ( ?). 

Negri  bodies  for  diagnostic  purposes  are  best  demonstrated  by  im- 
pression preparations  of  Ammon's  horn  and  cerebellum  stained  according 
to  Van  Gieson,  as  recommended  by  Frothingham;  or  smears  stained  in 
a  similar  manner  as  recommended  by  Williams  and  Lowden.  Smears  are 
prepared  by  placing  a  small  portion  of  the  brain  matter  near  one  end 
of  a  slide,  crushing  with  a  cover  glass  and  spreading  over  the  rest  of  the 
slide;  portions  are  selected  from  Ammon's  horn,  cerebellum,  cerebral 
cortex,  and  medulla.     Impression  preparations  are  made  by  pressing  a 


THE  VENEKEAL  DISEASES  53 

slide  upon  the  cut  surface  of  Amnion's  horn,  or  other  parts  of  the 
brain,  and  lifting  with  a  quick  movement.  The  chief  advantage  of 
this  method  is  that  the  characteristic  arrangement  of  the  cells  of  the 
hippocampus  (which  rarely  fail  to  contain  Negri  bodies)  is  undisturbed, 
and  consequently  desired  cells  are  readily  found  and  examined  for 
bodies ;  moreover,  there  is  no  danger  of  contaminating  the  fingers.  Such 
impressions  are:  (1)  fixed,  while  still  moist,  in  methyl  alcohol  for  one- 
half  minute  or  longer;  (2)  stained  with  Van  Gieson,  while  still  moist 
with  alcohol,  steaming  lightly  for  one-half  to  one  minute;  (3)  washed 
under  tap;  (4)  blotted  with  filter  paper.  Frothingham's  modification 
of  Van  Gieson's  stain  is:  Tap  water  20  c.  c. ;  saturated  alcoholic  solu- 
tion fuchsin  (f.  Bac.  Griibler)  1  drop;  saturated  aqueous  solution 
methylene  blue  (f.  Bac.  Koch.  Griibler)  1  drop.  The  stain  remains 
good  for  three  days. 

3.  The  lesions  of  Van  Gehuchten  and  Nelis,  described  in  1900,  are 
the  most  characteristic  anatomical  changes.  These  lesions  are  found  in 
the  peripheral  ganglia  of  the  cerebrospinal  and  sympathetic  systems, 
especially  in  the  plexiform  ganglia  of  the  pneumogastric  nerve,  and  the 
Gasserian  ganglia.  The  normal  nerve  cells  of  these  ganglia  lie  in  a 
capsule  lined  with  a  single  layer  of  endothelial  cells.  In  rabies  these 
endothelial  cells  proliferate  and  the  nerve  cells  are  partly  or  entirely 
destroyed  and  replaced  by  diverse  cells  associated  with  chronic  inflamma- 
tory processes. 

4.  The  final  diagnosis  of  rabies  rests  upon  animal  experimentation. 
A  small  quantity  of  the  suspected  material  is  placed  under  the  dura 
mater  of  a  rabbit  or  guinea-pig.  The  diagnosis  by  this  method,  however, 
requires  so  much  time  (on  account  of  the  long  period  of  incubation 
of  the  disease)  that  it  is  of  no  practical  value  in  deciding  whether  or 
not  the  Pasteur  prophylactic  treatment  should  be  given,  but.  in  any 
critical  case  the  positive  evidence  furnished  by  animal  experimentation 
is  incontrovertible. 


THE  VENEREAL  DISEASES 

As  a  danger  to  the  public  health,  as  a  peril  to  the  family,  and  as  a 
menace  to  the  vitality,  health,  and  physical  progress  of  the  race,  the 
venereal  diseases  are  justly  regarded  as  the  greatest  of  modern  plagues, 
and  their  prophylaxis  the  most  pressing  problem  of  preventive  medicine 
that  confronts  us  at  the  present  day. 

No  serious  attempt  was  made  by  the  sanitary  authorities  of  any 
of  our  great  cities  to  deal  with  this  problem  until  New  York  City  in 
1912  ^   determined  to  treat  the  venereal  diseases  as  any  other  highly 

1  Resolutions  adopted  hj  the  Board  of  Health,  February  20th. 


54  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

communicable  and  preventable  infection,  dealing  purely  with  the  sani- 
tary features  of  the  problem  from  a  public  health  standpoint,  ignoring 
the  social  and  moral  phases.  The  opposition  to  such  activity  is  slowly 
being  broken  down.  Progress  against  the  venereal  diseases  is  a  repeti- 
tion of  the  warfare  along  other  lines  of  sanitation  and  hygiene.  It  is 
the  history  of  a  continuous  struggle  carried  on  in  the  name  of  law, 
religion,  personal  rights,  or  expediency.  Although  the  difficulties  in 
this  case  are  much  greater  than  in  any  other  group  of  diseases,  an 
intelligent  and  persistent  campaign  must  end  in  a  long-delayed  success. 

Biggs  states  that  in  1912  at  least  800,000  people,  or  more  than  one- 
fifth  of  the  adult  population  of  New  York  City,  have,  or  have  had,  some 
venereal  disease,  and  that  in  a  large  percentage  of  these  persons  the 
disease  is  still  active.  The  number  of  new  infections  occurring  each 
year  probably  exceeds  that  of  all  other  notifiable  diseases  combined. 
In  view  of  such  figures  the  magnitude  and  the  importance  of  the  problem 
of  administrative  control,  as  applied  to  these  diseases,  become  clearly 
apparent. 

There  are  three  venereal  diseases :  syphilis,  gonorrhea,  and  chancroid. 
In  order  to  have  a  clear  understanding  of  the  problems  of  venereal 
prophylaxis  it  is  necessary  to  have  a  knowledge  of  the  essential  features 
of  these  preventable  infections.  Two  of  them,  syphilis  and  gonorrhea, 
are  of  great  importance,  because  they  are  very  prevalent  and  because 
they  are  very  serious  infections  with  grave  consequences. 

SYPHILIS 

There  are  many  striking  things  about  syphilis,  but  nothing  so  strik- 
ing as  its  persistence  in  spite  of  knowledge  complete  enough  to  stamp 
it  out  and  in  view  of  the  popular  dread  in  which  the  disease  is  held. 
It  is  preventable,  even  curable — ^yet  scarcely  another  disease  equals  it 
in  the  extent  and  intensity  of  its  ravages.  It  is  one  of  the  great  cankers 
of  humanity. 

Syphilis  is  a  good  illustration  of  the  fact  that  it  is  much  more  diffi- 
cult to  control  a  disease  transmitted  directly  from  man  to  man  than  a 
disease  transmitted  by  an  intermediate  host,  or  one  in  which  the  infective 
principle  is  transferred  through  our  environment.  We  have  a  certain 
amount  of  control  over  our  surroundings,  and  we  have  dominion  over 
the  lower  animals,  but  the  control  of  man  requires  the  consent  of  the 
governed. 

There  is  an  accurate  historical  record  of  the  startling  spread  of 
syphilis  over  the  known  world  in  a  few  years  after  1495,  and  from  that 
time  it  has  everywhere  been  endemic.  No  similar  record  exists  of  the 
sudden  establishment  of  any  other  great  disease  among  the  larger  part 
of  the  earth's  inhabitants.     All  evidence,  however,  points  to  the  severe 


THE   VENEEEAL   DISEASES  55 

character  of  the  disease  during  this  epidemic,  the  cases  running  an 
acute,  febrile  course,  accompanied  by  symptoms  of  such  severity  as  are 
now  seen  only  in  very  unusual  cases.  Syphilis  was  unknown  before  the 
year  1493.  It  was  probably  brought  by  the  crew  of  Columbus,  on  his 
first  voyage  from  Espanola,  or  Hayti.^  Some  of  the  returning  crew 
accompanied  Charles  VIII  of  France  in  the  Autumn  of  1494  with  the 
army,  32,000  strong,  which  invaded  Italy  for  the  conquest  of  Naples. 
The  epidemic  began  in  Italy  at  this  time  and  the  disease  spread  quickly 
over  Europe  with  the  scattering  of  the  troops. 

Civilization  and  syphilization  have  been  close  companions,  but  syph- 
ilis is  now  less  prevalent  among  civilized  than  uncivilized  peoples — this 
is  promising.  Civilization,  however,  should  not  be  content  until  it  has 
controlled  syphilis  as  effectively  as  it  has  a  few  other  preventable 
infections.  The  effort  to  do  so,  at  least,  must  be  persistent  and 
sincere. 

From  the  economic  side,  syphilis  is  not  a  serious  disease  in  its  pri- 
mary and  secondary  stages;  that  is,  persons  with  syphilis  during  the 
early  stages  are  usually  not  ill  enough  to  cease  work.  Acutely  fatal 
cases,  such  as  frequently  occurred  in  the  sixteenth  century,  are  now 
rare;  in  other  words,  the  disease  has  lost  much  of  its  early  virulence. 
It  is  the  late  manifestations,  the  sequelae  and  the  so-called  parasyphilitic 
lesions,  as  well  as  the  inherited  consequences  of  the  disease,  that  play 
havoc.  About  one-fifth  of  all  the  insane  in  our  asylums  are  cases  of 
general  paresis;  90  per  cent,  of  these  give  the  Wassermann  reaction. 
Syphilis,  alcohol,  and  heredity  fill  our  insane  asylums. 

The  consequences  of  syphilis  are  often  more  severe  upon  the  off- 
spring than  upon  the  syphilitic  parent.  The  infection  itself,  or  various 
defects,  especially  of  the  nervous  system,  resulting  from  the  conse- 
quences of  syphilis,  may  be  transmitted  from  parent  to  child,  often  with 
fatal  results.  When  death  does  not  ensue  the  results  may  be  still  more 
tragic. 

Syphilis  is  an  infection  caused  by  the  Treponema  pallidum  (formerly 
known  as  the  Spirochaeta  pallida).  It  is  a  communicable  disease  ac- 
quired by  direct  contact  with  infected  persons  or  things.  It  runs  a 
chronic  course  with  local  and  general  manifestations,  usually  divided 
into  three  stages,  which  are  not  always  well  defined.  The  primary 
stage  consists  of  the  chancre  which  forms  at  the  site  of  the  initial  infec- 
tion. The  chancre  is  a  hard  indurated  ulcer  in  the  skin  or  mucous 
membrane,  and  appears  about  three  weeks  (not  less  than  ten  days) 
after  the  receipt  of  the  infection.  The  secondary  stage  is  characterized 
by  a  general  invasion  of  the  spirochete  throughout  the  system,  as  indi- 
cated by  a  general  involvement  of  the  lymph  nodes,  eruptions  upon  the 
skin  and  mucous  membranes,  fever,  anemia,  and  other  indications  of 

^Jour.  A.  M.  A.,  June  12,  1915,  LXIV,  24,  p.  1962. 


56  DISEASES  HAVING  SPECIAL  PKOPHYLAXIS 

a  generalized  infection.  The  third  stage  is  character i zed  hy  a  localized 
granulomatous  growth  known  as  a  gumma,  (iummata  may  appear  in 
almost  any  tissue  or  organ  of  the  body.  A  fourth  stage  is  often  added 
to  the  picture,  consisting  of  the  sequelae  or  parasyphilitic  phenomena, 
such  as  general  paresis,  arteriosclerosis,  locomotor  ataxia,  aneurysm,  etc. 
Noguchi  has  recently  demonstrated  the  presence  of  the  treponema  in 
some  of  these  late  lesions. 

The  health  officer  should  regard  syphilis  just  as  he  does  the  acute 
febrile  exanthematous  diseases.  Because  syphilis  runs  a  slow  and  often 
chronic  course  with  mild  constitutional  symptoms  during  its  early  stages, 
it  is  often  placed  in  a  class  by  itself.  This  is  a  mistake.  Syphilis  has 
its  period  of  incubation,  eruption,  and  decline,  just  as  measles  and 
smallpox  have. 

There  is  no  natural  immunity  to  syphilis ;  all  are  susceptible,  but  the 
severity  of  individual  cases  varies  greatly.  This  is  due  either  to  the 
virulence  of  the  strain,  the  amount  of  the  infection,  or  to  variation  in 
individual  resistance. 

One  attack  of  syphilis  confers  an  immunity,  in  that  reinfections  do 
not  produce  another  chancre.  That  is,  the  virus  cannot  be  inoculated 
upon  a  person  who  has  or  has  had  the  disease.  If  the  disease  is  aborted 
by  the  timely  use  of  salvarsan,  reinfection  may  take  place.  The  im- 
munity is  peculiar  in  that,  while  the  person  cannot  have  a  second 
chancre,  this  fact  has  no  influence  upon  the  development  of  the  sec- 
ondary and  tertiary  lesions  resulting  from  the  first  infection.  For  CoUes' 
and  Profeta's  laws  of  syphilitic  immunity  and  the  transmission  of 
syphilis  see  page  503. 

In  a  large  majority  of  all  cases  of  syphilis  the  infection  is  trans- 
mitted during  sexual  approach.  It  is,  therefore,  spoken  of  as  a  venereal 
disease;  many  cases,  however,  are  contracted  out  of  venery.  These  acci- 
dental infections  are  more  common  than  is  ordinarily  supposed.  Metch- 
nikoff  reports  that  a  great  number  of  cases  of  non-venereal  syphilis 
occur  among  children  in  Eussia,  where  the  peasants  live  huddled  to- 
gether and  in  ignorance.  Syphilis  may  be  passed  from  one  person  to 
another  by  kissing,  and  the  danger  is  greater  when  there  are  mucous 
patches  or  other  open  lesions  upon  the  mouth.  The  disease  may  also 
be  transmitted  in  wounds  inflicted  by  the  teeth  of  syphilitics.  In  sur- 
gery and  midwifery  practice  physicians  are  not  infrequently  infected 
through  minute  abrasions — a  pin  prick  or  a  scratch  from  a  scalpel  is 
sufficient  to  introduce  the  virus.  Midwifery  chancres  are  usually  upon 
the  fingers.  Chancre  of  the  lip  is  the  most  common  of  the  erratic  or 
extragenital  forms,  and  may  be  acquired  in  many  ways  apart  from  direct 
infection,  such  as  the  use  of  spoons,  glasses,  pipes,  etc.,  which  have 
recently  been  mouthed  by  a  syphilitic.  The  virus  may  also  be  trans- 
mitted by  towels,  clothing,  razors,  handkerchiefs,  surgical  and  dental 


THE  VENEEEAL  DISEASES  57 

instruments,  human  vaccine  virus,  etc.  The  list  of  articles  that  have 
conveyed  the  contagium  is  comprehensive. 

The  spirochete  of  syphilis  is  a  frail  organism,  yet  it  may  live  long 
enough  on  towels  and  other  objects  to  command  hygienic  respect.  Thus, 
Zinsser  and  Hopkins  ^  found  that  pure  cultures  lived  III/2  hours  on  a 
moist  towel.  Dried  on  covered  slips,  the  spirochete  failed  to  grow  after 
one  hour.  Bronfenbrenner  and  ISToguchi  ^  found  that  the  viability  of 
the  spirochete  is  markedly  diminished  by  lack  of  nutritive  substances, 
presence  of  oxygen,  effect  of  light  and  the  toxic  effect  of  sodium  chlorid. 

Chancres  of  the  mouth  and  on  the  tonsils  result,  as  a  rule,  from  per- 
verted practices.  Wet  nurses  are  sometimes  infected  on  the  nipple,  and 
it  occasionally  happens  that  the  relatives  of  a  syphilitic  child  are  acci- 
dentally infected.  The  hereditary  and  congenital  transmission  of  syph- 
ilis is  discussed  on  page  502. 

Syphilis  lowers  the  standard  of  health  and  paves  the  way  for  other 
diseases.  Whatever  the  etiological  relationship  may  be,  it  is  definitely 
known  that  syphilitics  are  prone  to  die  early  from  affections  of  the  heart 
and  vessels,  general  paresis,  diseases  of  the  central  nervous  system  (loco- 
motor ataxia),  chronic  nephritis,  arteriosclerosis,  aneurysm,  apoplexy, 
etc.  The  actuaries  of  all  life  insurance  companies  know  that  the  mor- 
bidity and  mortality  rates  among  syphilitics  are  very  much  higher  than 
those  of  any  other  class  of  individuals  of  the  community  who  enjoy  ap- 
parent good  health  at  the  time  of  examination. 

Most  insurance  companies  refuse  to  accept  syphilitics  at  all.  Some 
companies  require  extra  premiums  to  compensate  for  the  extra  risks;  a 
few  companies  will  accept  exceptionally  favorable  cases  who  have  had 
a  thorough  course  of  treatment,  and  who  have  shown  no  symptoms  for 
3  to  5  years,  but  under  these  circumstances  only  special  policies  are 
contracted  for  which  do  not  keep  the  applicant  on  the  companies'  books 
after  55  years  of  age.  Syphilis  is  the  chief  cause  of  death  in  early  adult 
life  in  persons  otherwise  hale  and  hearty. 

Osier  estimates  that  between  6,000  and  7,000  persons  succumb  to 
syphilis  each  year  in  England  and  Wales,  and  he  puts  syphilis  in  a  class 
next  to  tuberculosis,  pneumonia,  and  cancer  as  a  cause  of  death.  Mat- 
tauschek  and  Pilcz  ^  found  that  4,134  officers  of  the  Austrian  army  con- 
tracted syphilis  between  1880  and  1900.  Twenty  died  from  the  dis- 
ease, 198  had  general , paresis,  113  have  locomotor  ataxia,  133  have  cere- 
brospinal syphilis,  and  of  this  latter  number  80  are  insane.  This  gives 
a  total  of  14.64  per  cent,  of  these  better-class  men  dead  or  disabled  as  a 
result  of  syphilis. 

Syphilis  was  regarded  as  an  infection  peculiar  to  man  until  ISTicolle 

^Jour.  A.  M.  A.,  LXII,  23,  June  6,  1914. 

^Jour.  of  Phar.  and  Exp.  Therap.,  Baltimore,  March,  IV,  4,  pp.  251-362. 

^Med.  Klin.,  1913,  IX,  1544. 


58  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

and  Hamonic  in  1902,  and  Metchnikoff  and  lioux  jn  1903,  transmitted 
the  disease  to  the  higher  apes.  Later  it  was  found  that  monkeys  and 
rabbits  are  susceptible.  As  a  result  of  these  experiments  certain  impor- 
tant facts  in  reference  to  prophylaxis  were  discovered.  Metchnikoff 
and  Eoux  found  that  bichlorid  of  mercury,  1-2,000,  applied  one  hour 
after  inoculation,  does  not  prevent  the  development  of  the  primary 
lesion  in  the  monkey.  This  is  probably  due  to  the  fact  that  the  action 
of  the  bichlorid  is  limited  to  the  surface;  it  lacks  penetration  owing 
to  its  well-known  property  of  coagulating  albumin.  Other  antiseptics 
were  tested,  but  in  a  long  series  of  experiments,  carried  out  on  chim- 
panzees, baboons,  and  Macacus  monkeys,  Metchnikoff  and  Eoux  showed 
that  mercurial  inunctions  are  most  successful  in  preventing  the  devel- 
opment of  the  chancre.  The  mercurial  inunctions  may  be  made  with 
metallic  mercury,  calomel,  white  precipitate  (ammoniated  mercury), 
or  salicylarsenite  of  mercury.  Calomel  ointment  appears  to  be  the  best, 
and  is  the  one  now  generally  used.  It  is  rubbed  up  in  lanolin  in  the 
proportions  of  1  to  3  or  1  to  4.  The  ointment  should  be  rubbed  and  left 
upon  the  place  for  4  to  5  minutes  and  not  later  than  20  hours  after 
the  receipt  of  the  infection.  This  will  usually  prevent  the  development 
of  the  disease.  Excision,  or  destruction  of  the  chancre  with  the  actual 
cautery  or  with  corrosive  antiseptics  does  not  influence  the  development 
of  the  disease. 

GONORRHEA 

Gonorrhea  is  much  more  prevalent  than  syphilis,  and  common  opin- 
ion regards  it  as  a  mild  and  not  very  shameful  disease,  that  is,  "no  worse 
than  an  ordinary  cold."  As  a  matter  of  fact,  gonorrhea  is  one  of  the 
serious  infectious  diseases,  and  the  gonococcus  occupies  a  position  of 
high  rank  among  the  virulent  pathogenic  microorganisms.  From  an 
economic  and  public  health  standpoint,  gonorrhea  does  not  fall  very 
far  short  of  syphilis  in  importance ;  in  fact,  some  give  it  first  place. 

The  serious  consequences  of  gonorrhea  are :  complications  such  as 
periurethral  abscess,  gonorrheal  prostatitis  in  the  male,  and  vaginitis, 
endocervicitis,  and  inflammation  of  the  glands  of  Bartholin  in  the 
female.  Perhaps  the  most  serious  of  all  the  sequelae  of  gonorrhea  are 
those  which  result  from  the  spread  by  direct  continuity  of  tissues,  such 
as  inflammation  of  the  Fallopian  tube,  and  sometimes  of  the  endo- 
metrium, the  ovary,  or  even  the  peritoneum.  The  gonococcus  has  been 
found  in  pure  culture  in  cases  of  acute  general  peritonitis.  Other  inflam- 
mations caused  by  the  spread  of  the  infection  are  cystitis,  which  some- 
times extends  upward  through  the  ureters  to  the  kidneys. 

The  gonococcus  sometimes  invades  the  blood  and  produces  a  general 
septicemia  and  pyemia ;  death  may  occur  from  acute  endocarditis.  Gon- 
orrheal arthritis  is,  in  many  respects,  the  most  damaging,   disabling. 


THE   VENEEEAL  DISEASES  69 

and  serious  of  all  the  complications  of  gonorrhea.  It  may  even  follow 
ophthalmia  neonatorum.  It  is  more  frequent  in  males  than  in  females, 
but  a  gonorrheal  arthritis  of  great  intensity  may  occur  in  a  newly  mar- 
ried woman  infected  by  an  old  gleet  in  her  husband  (Osier).  The 
serious  nature  of  gonorrheal  complications  in  the  eye  will  be  considered 
separately  under  Ophthalmia  N^eonatorum.  Gynecologists  tell  us  that 
the  greater  part  of  their  practice  is  made  up  of  the  consequences  of 
gonorrhea. 

Sterility  is  one  of  the  serious  consequences  of  gonorrhea.  This  may 
be  caused  in  the  male  through  epididymitis,  which  is  a  very  common 
complication,  and  in  the  female  by  salpingitis,  which  closes  or  obstructs 
the  Fallopian  tube.  Gonorrhea  is  said  to  be  the  cause  of  about  one-half 
of  all  cases  of  sterility.  Stricture  of  the  urethra  in  the  male  is  a  fre- 
quent sequel. 

Gonorrhea  is  usually  transmitted  by  sexual  congress;  however,  acci- 
dental or  innocent  infections  are  not  infrequent,  especially  in  children. 

Gonorrhea  in  Children,. — Vulvovaginitis  is  common  in  children  and 
is  frequently  due  to  the  gonococcus.  Outbreaks  are  common  in  schools, 
tenements,  playgrounds,  asylums,  hospitals  or  wherever  children  con- 
gregate in  considerable  numbers  and  where  the  same  lavatories,  towels, 
nurses,  etc.,  are  provided  in  common.  Paul  Bendig  ^  reports  the  follow- 
ing instance :  Of  40  girls  sent  for  convalescence  to  a  brine  bath,  15 
showed  signs  of  gonorrhea  after  the  return.  The  infection  came  from 
an  eight-year-old  girl,  who  apparently  had  been  suffering  from  gon- 
orrhea for  several  years,  and  was  spread  through  indiscriminate  bathing 
in  one  bath  tub  and  the  use  of  the  same  bath  towel. 

Infants  may  contract  the  infection  from  the  hands  of  the  nurse. 
Towels,  diapers,  wash  cloths,  and  bed  linen  may  account  for  the  trans- 
mission of  the  gonococcus  in  hospitals  and  asylums,  although  the  rapidity 
with  which  the  gonococcus  dies  when  dried  diminishes  the  danger  some- 
what from  this  source.  Diapers  should  always  be  disinfected  by  boiling 
or  steaming  before  they  are  again  used,  especially  in  institutions.  This, 
not  only  on  account  of  gonorrhea,  but  infectious  diarrheas.  In  the  public 
bath  children  who  use  the  same  towel  or  soap  run  a  great  risk.  The 
gonococcus  may  live  a  long  time  upon  the  surface  of  soap.  Taussig  ^ 
believes  the  seat  of  the  water-closet  favors  the  infection  in  little  girls. 
These  seats  are  usually  too  high  and  thus  readily  become  smeared  with 
the  discharges  from  the  vagina,  and  thus  infect  others.  In  schools  and 
tenements  the  water-closets  are  often  used  by  a  stream  of  children  one 
after  another.    Hence  such  seats  should  be  low  and  U-shaped. 

The  frequency  of  gonorrhea  in  children  may  be  judged  from  the 
observations  of  Pollack,  who  reports  187  cases  treated  in  the  Woman's 

^  Miinchener  med.  Wochenschr.,  1909,  p.  1846. 

'Amer.  Jour.  Med.  Sciences,  CXLVIII,  4,  Oct.,  1914,  p.  480. 


60  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

Venereal  Department  of  Johns  Hopkins  Hospital  duriiig  the  year  1909/ 
Pollack  estimates  that  800  to  1,000  cliildren  are  infected  each  year  in 
Baltimore,  and  that  the  same  proportion  probably  holds  good  for  other 
cities.  Seippel  estimates  that  500  cases  occur  annually  in  Chicago.  One 
cause  of  the  infection  among  children  is  the  horrible  superstition  that 
a  person  infected  with  syphilis  or  gonorrhea  may  get  rid  of  it  by  infecting 
another — especially  a  virgin.  Gonorrhea  in  children  due  to  rape  is  rare. 
When  gonorrhea  enters  a  children's  hospital  or  an  infants'  home  it 
is  prone  to  become  epidemic  and  is  very  difficult  to  eradicate.  The 
story  of  the  infection  in  the  Babies'  Hospital,  New  York,  for  eleven 
years,  as  told  by  Holt,^  illustrates  the  singular  obstinacy  of  the  infec- 
tion. In  spite  of  the  greatest  care  and  precaution,  there  were,  in  1903, 
65  cases  of  vaginitis  with  2  of  ophthalmia  and  12  of  arthritis.  In 
1904  there  were  52  cases  of  vaginitis,  only  16  of  which  would  have 
been  recognized  without  the  bacteriological  examination.  In  all,  in 
the  eleven  years,  there  were  273  cases  of  vaginitis;  6  with  ophthalmia 
and  26  with  arthritis.  Holt  urges  isolation  and  prolonged  quarantine 
as  the  only  measures  to  combat  successfully  the  disease  (Osier).  It  is 
impossible  to  control  such  epidemics  without  bacteriological  diagnosis 
aided  by  complement  fixation  tests. 

CHANCBOID 

Chancroid  is  a  specific,  local,  auto-inoculable,  and  contagious  venereal 
ulcer,  caused  by  the  streptobacillus  of  Ducrey  (1889).  The  ulcers  are 
often  multiple  and  confer  no  immunity.  Chancroids  are  local  ulcers 
and,  unless  complications  set  in,  cause  no  sequelae  or  general  systemic 
effects,  such  as  follow  chancres.  Chancroids,  or  soft  chancres,  are  pe- 
culiarly liable  to  mixed  infections. 

A  little  soap  and  water  at  the  time  of  exposure  is  almost  an  absolute 
preventive  against  chancroid.  If  the  ulcer  has  developed  it  may  be 
aborted  by  cauterization,  provided  the  chancroid  is  not  more  than  three 
days  old.  Even  when  seven  days  old  the  ulcers  may  often  thus  be 
cured,  but  when  more  than  a  week  old  cauterization  should  not  be  em- 
ployed, for,  if  it  fails,  it  leaves  the  sore  larger  than  ever.  The  method 
of  cauterization  advised  by  Keyes  consists  in  washing  the  ulcers  with 
peroxid  of  hydrogen,  drying,  applying  pure  carbolic  acid,  then  pure 
nitric  acid,  washing  again  with  peroxid  of  hydrogen,  and  dusting  with 
calomel. 

Chancroids  are  usually  contracted  in  venery.  The  disease  should  not 
be  regarded  as  a  slight  or  negligible  malady,  for,  on  account  of  the  mixed 
infections  to  which  they  are  prone,  serious  consequences,  and  sometimes 

^  Johns  Hopkins  Hospital  Bulletin,  May,   1909,  p.   142. 
''New  York  Med.  Jour.,  March,  1905. 


.      VENEEEAL  PEOPHYLAXIS  AND  HYGIENE   OF   SEX    61 

death,  may  result.  The  complications  of  the  ulcers  are  various  forms 
of  phimosis,  resulting  from  inflammation  and  swelling;  destruction  of 
the  frenum;  gangrene  and  phagedena;  lymphangitis,  with  inguinal 
adenitis.     The  inguinal  buboes  are  painful  and  frequently  suppurate. 

Chancroid  is  usually  given  subordinate  consideration  because  syphilis 
and  gonorrhea  are  much  more  prevalent  and  much  more  serious. 

VENEREAL  PROPHYLAXIS  AND  HYGIENE  OF  SEX 

The  same  principles  apply  to  the  prevention  of  the  venereal  diseases 
as  apply  to  the  prevention  of  other  communicable  diseases.  The  fight 
against  venereal  diseases,  however,  is  especially  complicated  and  difficult 
because  of  the  close  association  with  prostitution,  the  problems  of  sex 
hygiene,  and  alcoholism — in  fact,  the  question  pervades  the  woof  and 
warp  of  society.  There  are  three  primitive  appetites  of  man — hunger, 
thirst,  and  the  sexual  appetite.  The  first  two  persist  throughout  life; 
the  last  comes  on  at  puberty,  grows  stronger  during  adolescence,  and 
wanes  with  age.  Any  program  for  the  control  of  the  venereal  diseases 
or  the  hygiene  of  sex  must  take  into  account  the  fact  that  we  are  deal- 
ing with  a  primal,  impulsive,  and  natural  passion  which  is  the  greatest 
force  for  social  good,  when  used  in  accordance  with  the  laws  of  nature, 
but  may  result  in  dire  consequences  when  these  laws  are  transgressed. 
The  venereal  diseases  are  among  the  most  widespread  and  universal  of 
all  human  ills,  and  enter  more  largely  into  the  marring  of  domestic 
happiness  than  any  other  disease  known  to  man.  The  difficulties  of  the 
situation  should  not  deter  the  health  officer  and  all  those  who  labor  for 
social  uplift,  for  there  is  no  more  pressing  problem  in  preventive 
medicine. 

Prevalence. — The  prevalence  of  the  venereal  diseases  among  the  popu- 
lation at  large  can  only  be  approximated.  Definite  figures,  however, 
are  at  hand  for  selected  groups.  The  reports  from  the  armies  of  the 
various  nations  give  the  following  figures  :^ 

VENEREAL  INFECTIONS  PER  THOUSAND   MEN 


Year3 

Per  Thousand 

X905-6 

19  8 

1906 

28.6 

1907 

54.2 

1906 

62.7 

1907 

167.8 

1 907 

68.4 

MVhite  and  Melville,  Lancet,  London,  1911,  II,  1615. 


63 


DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 


Kober  ^  gives  a  somewhat  more  recent  and  more  detailed  table. 

DIFFERENTIATED  INFECTION  PER  THOUSAND   MEN 


Syphilis 


Chancroid 


Gonorrhea 


U.  S.  Army 1909 

U.  S.  Navy 1909 

Japanese  Navy 1907 

British  Navy 1908 

British  Army 1908 

Japanese  Army 1907 

Prussian  Army 1907 


30.45 
26.43 

37.46 

35.1 

10.1 

4.4 


30.77 
28.23 

17.87 

28.23 

10.4 

2.1 


135.77 
105.11 

67.16 
40.7 
17.1 
12.2 


196.99 

159.83 

139.75 

122.49 

75.8 

37.6 

18.7 


Both  these  tables  indicate  that  the  English-speaking  people  are,  in 
their  navy  and  military  organizations  at  least,  greater  sufferers  from 
venereal  infections  than  the  other  nations. 

In  civil  life  accurate  figures  are  not  obtainable.  Cunningham  ^  says 
that  60  per  cent,  of  men  acquire  venereal  infection  some  time.  Ger- 
rish  ^  estimates  that  10  per  cent,  of  the  population  of  New  York  has 
syphilis.  Eischer  *  guesses  that  18  per  cent,  represents  the  syphilitic 
cases  in  the  United  States,  and  further,  that  there  are  250,000  deaths 
each  year  due  to  venereal  infection.  Biggs  ^  judges  that  there  were  about 
200,000  cases  of  venereal  disease  in  the  city  of  New  York  in  1912.  Mor- 
row ^  states  that  75  per  cent,  of  adult  males  acquire  gonorrhea  at  some 
time,  and  that  from  5  to  10  per  cent,  acquire  syphilis ;  these  figures  are 
based,  not  alone  on  his  own  observations,  but  on  the  opinion  of  such 
men  as  Neisser  and  Fournier.  The  pathologists  of  Melbourne,  Australia, 
found  syphilitic  lesions  in  30  per  cent,  of  200  necropsies;  furthermore, 
5  per  cent,  of  the  population  within  a  ten-mile  radius  from  the  Mel- 
bourne postoffice  were  positive  to  the  Wassermann  test.  Banks  ^  states 
that  we  have  nearly  two  and  one-half  million  cases  of  venereal  diseases 
occurring  yearly  in  the  United  States — about  one  person  in  every  forty. 

Attitude. — Our  attitude,  toward  the  venereal  diseases  is  very  incon- 
sistent. There  is  a  natural  aversion  toward  these  afflictions.  The  sani- 
tarian should  make  no  distinction  between  the  venereal  diseases  and 
other  epidemic  diseases;  he  should  regard  the  greatpox  in  the  same 
light  that  he  regards  the  smallpox.  The  principles  for  the  control  of 
syphilis  and  gonorrhea  differ  in  no  wise  from  those   used  to   control 

^  Kober,  Tr.  Assn.  Am.  Phys.,  Phila.,   1911,  XXVT,   155. 

"Cunningham,  Boston  Med.  and  Surg.  Jour.,  1913,  LXVIII,  77. 

^Gerrisli,  "Social  Diseases,"  New  York,   1911,  II,   1. 

*  Fischer,  PuUic  Health,  Lansing,  Mich.,   1913,  VIII,  51. 

s  Biggs,  N.  Y.  Med.  Jour.,  1913,  XCVIII,  1009. 

"Morrow,  Boston  Med.  and  Surg.  Jour.,  1911,  CLXV,  520. 

Tub.  Health  Rep.,  Feb.  26,  1915,  XXX,  9,  p.  618. 


VENEEEAL  PROPHYLAXIS  AND  HYGIENE   OF   SEX    63 

smallpox,  leprosy,  tuberculosis,  measles,  diphtheria,  etc.  The  health 
officer  must  not  regard  venereal  disease  as  a  punishment  for  sin  and 
crime — the  victim  or  culprit  needs  help  and  sympathy.  The  immediate 
problem  is  the  prevention  of  further  spread  of  the  infection.  A  person 
afflicted  with  a  venereal  disease  should  be  treated  in  the  same  humane 
spirit  that  actuates  the  physician  in  other  diseases.  Furthermore,  the 
interests  of  the  community  require  that  the  patient  be  accorded  the  best 
possible  care  and  attention.  The  usual  attitude  toward  the  venereal 
diseases  may  well  startle  us  when  we  consider  that  in  most  of  our  large 
cities  no  hospital  will  take  a  case  of  syphilis  or  gonorrhea  during  the 
acute  stages,  when  these  diseases  are  especially  communicable.  Morrow 
holds  that  the  notoriously  inadequate  provision  made  for  the  reception 
and  treatment  of  venereal  patients  is  a  disgrace  to  our  civilization.  For- 
merly lepers  were  segregated  in  vile  lazarettos  and  cases  of  smallpox 
isolated  in  horrible  pesthouses;  now  we  have  comfortable  and  congenial 
isolation  wards  or  special  sanatoria  for  these  diseases.  From  the  stand- 
point of  prevention  suitable  hospital  accommodations  should  be  provided 
for  those  having  venereal  diseases. 

Education. — Education  in  sex  hygiene  and  the  venereal  peril  accom- 
plishes a  certain  amount  of  good.  It  may  be  questioned  how  much  a 
knowledge  of  the  consequences  will  prevent  some  persons  committing 
crime.  However,  the  old-style  innocence  must  be  regarded  as  present- 
day  ignorance.  Every  boy  and  girl,  before  reaching  the  age  of  puberty, 
should  have  a  knowledge  of  sex,  and  every  man  and  woman  before  the 
marriageable  age  should  be  informed  on  the  subject  of  reproduction 
and  the  dangers  of  venereal  diseases.  Superficial  information  is  not 
true  education.  On  the  other  hand,  it  is  a  mistake  to  dwell  unduly 
upon  the  subject,  for  in  many  instances  the  imagination  and  passion 
of  youth  are  inflamed  by  simply  calling  attention  to  the  subject.  One 
of  the  objects  of  education  is  to  avoid  the  dangers  of  sex  impurities, 
and  all  agree  that  this  may  often  best  be  accomplished  by  keeping  the 
mind  clean,  that  is,  away  from  the  subject.  The  education  must, 
therefore,  be  clear,  pointed,  brief,  and  direct.  The  object  of  educa- 
tion is  not  alone  to  help  the  individual  to  help  himself,  but  to  influence 
necessary  legislation  and  concerted  public  action;  also  to  lessen  the 
influence  of  quacks.  A  simple  knowledge  of  the  facts  is  a  sufficient 
deterrent  for  some;  others  may  be  influenced  through  fear  of  the  con- 
sequences. Boys,  as  a  rule,  cannot  be  controlled  through  fear.  The 
spirit  of  adventure  is  rife  in  healthy  lads;  they  love  to  take  a  chance. 
Boys  may  be  reached  by  an  appeal  to  their  better  natures  and  by  allu- 
sions to  sister  or  mother. 

Instruction  in  sex  hygiene  should  emphasize  the  rewards  of  strength 
and  virtue,  rather  than  the  penalties  of  weakness  and  vice.  The  only 
foundation  for  a  healthy  sex  life  is  an  individual  and  social  morality, 


64  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

combined  with  a  knowledge  and  full  understanding  of  sexual  realities. 
The  teaching  of  sex  from  a  biological  standpoint  alone  is  inadequate,  for 
there  is  little  basis  for  character  forming  or  ethical  instruction  in  the 
physical  analogies  of  animal  and  plant  life.  Instruction  should  be  posi- 
tive rather  than  negative,  constructive  rather  than  destructive.  The 
fear  of  disease  or  fear  of  anything  else  is  not  a  sufficient  motive  for 
goodness.  In  contrast  to  the  usual  procedures,  the  emphasis  should  be 
placed  on  the  beauty  of  goodness  rather  than  on  the  ugliness  of  vice. 

In  general,  it  may  be  said  that  the  best  plan  of  education  in  mat- 
ters sexual  is  to  answer  the  questions  of  children  upon  the  subject  of 
maternity  frankly  and  truthfully,  but  to  offer  them  no  information  on 
the  subject".  The  growing  child  at  the  age  of  puberty  should  be  offered 
a  certain  amount  of  information  concerning  unnatural  habits  and  should 
study  physiology,  biology,  especially  botany,  and  the  facts  of  fertiliza- 
tion. At  about  the  age  of  sixteen  or  eighteen  girls  as  well  as  boys 
should  be  instructed  as  to  the  venereal  peril.  The  person  to  impart  the 
information  may  be  parent,  doctor,  minister,  friend,  or  teacher — in  any 
event,  two  qualifications  are  essential:  (1)  Knowledge  of  the  facts; 
(2)  an  impressive  personality.  As  a  rule  the  school-teacher  is  not 
naturally  endowed  nor  is  the  class-room  the  best  place  to  teach  lessons 
in  sex  hygiene.  The  literature  of  the  American  Social  Hygiene  Asso- 
ciation, 105  West  40th  St.,  Few  York,  is  admirable.  One  circular  is 
for  young  men,  another  for  young  women,  and  a  third  for  those  having 
venereal  disease. 

Some  of  the  facts  all  young  men  should  know  are:  that  the  true 
purpose  of  the  sex  function  is  reproduction  and  not  sensual  pleasure; 
that  the  testicles  have  a  twofold  function,  (a)  reproduction  and  (b)  to 
supply  force  and  energy  to  other  organs  of  the  body;  that  occasional 
seminal  emissions  at  night  are  evidences  of  normal  physiological  activity ; 
that  sexual  intercourse  is  not  essential  to  the  preservation  of  virility; 
that  chastity  is  compatible  with  health ;  and  that  the  sex  instinct  in  man 
may  be  controlled. 

The  primary  function  of  the  testicles  is  to  build  the  boy  into  the 
man.  Castration  in  early  life,  as  in  the  case  of  eunuchs,  results  in 
a  loss  of  the  internal  secretion  of  the  testicles  and  a  failure  in  develop- 
ment of  the  secondary  sexual  characters  which  distinguish  the  male. 
There  are  an  alteration  in  physical  conformation  and  in  the  voice,  lack 
of  beard,  development  of  the  mamma,  etc. — in  other  words,  an  approach 
to  the  feminine  type.  Healthy  sexuality  stimulates  the  imagination, 
sentiment,  the  esthetic  sense,  and  the  higher  creative  functions.  Excesses 
or  any  influence  which  weakens  the  sexual  system  impair  the  will  power, 
influence  self-respect,  and  diminish  mental  force.  Experience  shows 
that  arduous  physical  and  mental  labor,  even  after  maturity  is  attained, 
is  best  performed  when  the  sex  organs  are  not  exercised;  that  is,  sexual 


VENEEEAL  PROPHYLAXIS  AXD  HYGIENE   OF   SEX    65 

excess  distinctly  impairs  muscular  strength  and  mental  efficiency.  It 
is  unwise  to  frighten  boys  by  exaggerating  the  results  of  self-abuse, 
which  is  rather  the  effect  and  not  the  cause  of  idiocy,  insanity,  degen- 
eracy, and  other  defects  of  the  central  nervous  organization.  Self-abuse 
is  no  worse  in  its  effects  than  natural  coitus,  except  for  its  influence 
upon  character.     Both  are  alike  harmful  when  indulged  in  to  excess. 

Eesults  through  education  will  be  slow,  for  the  aggressive  conscience 
of  the  world  in  these  matters  has  awakened  too  recently  to  have 
achieved  as  yet  a  great  deal. 

Registration  of  Cases. — It  is  not  possible  to  control  any  communi- 
cable disease,  especially  one  that  is  pandemic,  such  as  syphilis  or  gonor- 
rhea, without  a  knowledge  of  the  cases  and  deaths.  It  is  perhaps  even 
more  important  to  collect  morbidity  and  mortality  statistics  of  the  great- 
pox  than  it  is  of  the  smallpox.  But  the  public  registration  of  private 
disease  at  once  defeats  its  own  object.  Compulsory  methods  have  here- 
tofore failed,  and  little  may  be  expected  from  voluntary  registration. 
When  we  consider  that  in  our  country  we  have  no  means  of  knowing 
the  amount  and  distribution  of  smallpox,  except  to  a  limited  degree  in 
the  registration  area  (which  is  less  than  one-half  of  our  domain),  what 
can  we  expect  from  the  registration  of  the  closely  guarded  secrets  of 
the  underworld?  The  public  registration  of  ophthalmia  neonatorum  is 
successful  because  this  form  of  gonorrhea  is  so  apparent  and  the  con- 
sequences so  immediate  and  serious.  The  difficulties,  however,  need  not 
deter  us,  and  registration  should  be  attempted  even  though  the  returns 
are  incomplete.  A  start  should  be  made,  and,  though  the  returns  will 
be  only  partial  at  first,  a  gradual  improvement  may  be  expected.  Every 
case  known  and  properly  cared  for  is  a  focus  of  infection  neutralized. 

Continence. — One  of  the  important  facts  to  teach  boys  is  that  con- 
tinence is  compatible  with  health.  The  testicles  are  like  the  tear  glands 
and  the  sweat  glands,  in  that  they  do  not  atrophy  with  disuse.  Ben- 
jamin Franklin  taught,  as  many  another  man  of  influence  believes  to-day, 
that  the  exercise  of  the  sexual  functions  is  necessary  for  health.  This 
is  a  mistake  and  has  done  much  harm. 

The  sex  principle  is  universal  in  nature.  It  is  the  force  behind 
the  constructive  and  progressive  processes  of  all  life,  from  the  color 
adaptations  of  birds  and  flowers  to  the  highest  leadership  in  men.  Ee- 
production  is  only  one  of  its  many  functions ;  and  the  man  who  assumes 
that  the  so-called  physical  desire  that  at  times  thrills  him  indicates  a 
need  of  sexual  intercourse  is  in  danger  of  depleting  and  wasting  from 
his  life  a  chief  source  of  physical  and  mental  growth. 

The  single  standard  for  men  and  women  must  be  insisted  upon,  and 

the  parent  or  guardian  is  Justified  in  demanding  a  clean  bill  of  health 

of  the  young  man  who  proposes  marriage.     The  young  man,  in  turn,  is 

entitled  to  the  same  from  his  prospective  father-in-law.     One  of  the 

4 


66  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

defects  of  our  artificial  civilization  which  leads  to  harm  is  the  post- 
ponement of  the  marriage  age. 

To  denounce  youth  as  vicious  when  youth  has  merely  followed  the 
impulse  of  adolescence  is  futile,  because  youth  will  not  believe  this; 
other  and  juster  reasons  must  be  given,  if  youth  is  to  listen  and  be 
controlled;  and  any  young  man,  properly  warned  and  properly  in- 
formed will  not  be  merely  willing  but  anxious  to  learn  from  his  doctor 
before  marriage  if  he  is  fit  to  be  a  husband  and  a  father. 

Carnal  lust  may  be  cooled  and  quelled  by  hard  work  of  the  body, 
as  well  as  attention  to  personal  hygiene — hence,  one  of  the  great  ad- 
vantages of  athletic  sports  for  growing  young  men. 

Personal  Hygiene. — Idleness,  stimulating  food,  overeating,  impure 
thoughts,  evil  associates,  and  alcohol  excite  the  passions  and  are  the  bed- 
fellows of  the  venereal  diseases.  Purity  of  mind  and  cleanliness  of 
body  are  helpful  prophylactics.  Physical  exercise  and  an  out-of-door  life 
divert  the  mind  and  help  the  body ;  it  is  a  good  safety  valve  for  the  excess 
animalism  of  youth. 

The  public  should  be  taught  the  necessity  for  thorough  daily  cleans- 
ing of  the  external  genitals  in  both  sexes,  even  in  children.  The  large 
number  of  secreting  glands  and  the  decomposition  of  their  secretions 
are  liable  to  induce  irritation  and  even  minute  lesions  which  open  portals 
to  infection  of  all  kinds. 

Circumcision  is  recommended  as  an  aid  to  genital  cleanliness;  as  a 
prophylactic  against  syphilis  and  chancroid,  venereal  warts,  herpes,  and 
epithelioma,  balanitis  and  phimosis;  and  also  as  a  deterrent  to  mastur- 
bation. 

Alcohol. — The  strongest  indictment  against  alcohol  is  that  it  excites 
the  passions  and  at  the  same  time  diminishes  the  will  power.  The  fact 
that  alcohol  lowers  moral  tone  does  much  more  harm  than  all  the 
cirrhotic  livers,  hardened  arteries,  shrunken  kidneys,  inflamed  stomachs, 
and  other  lesions  believed  to  be  caused  by  its  excessive  use.  Alcohol  is 
not  a  stimulant,  but  depresses  the  higher  functions  of  the  brain  from 
the  beginning.     See  Index  for  references  to  Alcohol. 

Prostitution. — The  regulation  of  prostitution  by  means  of  medical 
inspection  has  been  tried  and  largely  abandoned.  In  other  words,  it  is 
a  failure,  for  the  reason  that  it  makes  vice  easy  and  is  therefore  morally 
wrong.  It  gives  a  false  sense  of  security  and  does  no-t  reach  clandestine 
prostitution,  which  is  the  great  source  of  the  venereal  diseases.  Under 
certain  limited  conditions,  such  as  in  army  encampments,  where  clan- 
destine prostitution  can  be  eliminated,  regulation  has  markedly  dimin- 
ished the  prevalence  of  venereal  disease. 

The  elimination  of  prostitution  is  beyond  the  dream  of  even  the 
theoretical  reformer.  Its  control  resolves  itself  into  questions  of  per- 
sonal hygiene  and  public  hygiene ;  it  is  inextricably  mixed  up  with  alco- 


VENEREAL  PROPHYLAXIS  AND  HYGIENE   OF   SEX    67 

holism,  and,  like  the  abuse  of  alcohol,  the  question  may  best  be  reached 
by  that  slower,  surer  process  of  improving  the  moral  and  physical  fiber 
of  man.^ 

Medical  Prophylaxis. — In  accordance  with  the  researches  of  Metch- 
nikoff  and  Roux  a  reasonably  efficient  prophylaxis  against  the  venereal 
diseases  is  now  possible. 

Calomel  ointment  (331^  per  cent.)  applied  within  an  hour  of  inter- 
course is  generally  effective  in  preventing  syphilitic  infection.  There 
are  several  more  or  less  efficient  irrigations  or  ointments  destructive  to 
the  gonococcus  if  used  soon  enough — the  silver  salts  being  the  best. 
Prophylaxis  is  therefore  possible,  but  it  takes  a  great  deal  of  care  and 
vigilance,  and  the  double  method  must  be  vigorously  applied  in  order 
to  be  effective.  It  has  been  used  with  success  in  armies  and  navies,  but 
in  civil  life,  where  strict  routine  and  control  of  men  are  impossible,  it 
is  impracticable  except  in  individuals ;  even  then  it  requires  time,  intelli- 
gence, and  sobriety. 

In  the  United  States  Navy  the  following  method  is  employed :  The 
entire  penis  is  scrubbed  with  liquid  soap  and  water  for  several  minutes, 
and  then  washed  well  with  a  solution  of  mercuric  bichlorid,  1  to  2,000 
in  strength.  If  there  are  any  abrasions  present,  they  are  sprayed  with 
hydrogen  peroxid  from  a  hand  atomizer.  The  man  is  then  placed  in 
a  sitting  position,  well  forward  in  a  chair  in  front  of  a  convenient  re- 
ceptacle, and  given  two  injections  of  a  10  per  cent,  solution  of  argyrol. 
He  is  required  to  retain  each  injection  in  the  urethra  for  five  minutes. 
After  taking  the  injections,  the  entire  penis  is  thoroughly  anointed  with 
a  33  per  cent,  calomel  ointment.  He  is  told  not  to  urinate  for  at  least 
two  hours,  and  to  allow  the  ointment  to  remain  on  the  penis  for  some 
hours.  A  temporary  dressing  is  placed  on  the  parts  to  protect  his 
clothes. 

The  measures  which  will  prevent  gonorrhea  will  not  ward  off  syphilis, 
and  vice  versa. 

The  results  attending  such  prophylactic  treatment  are  very  good. 
Thus  Ledbetter  ^  reports  that  at  Cavite,  before  medical  prophylaxis 
was  instituted,  the  percentage  of  venereal  diseases  of  all  classes  among 
the  men  averaged  from  25  to  30  per  cent,  annually,  and  at  times  even 
higher.  The  percentage  of  gonorrhea  was  reduced  to  8  per  cent,  annu- 
ally, and  this  percentage  included  about  30  patients  who  did  not  report 
for  treatment.  Chancroid  was  reduced  from  5  to  2  per  cent.,  which 
included  2  patients  not  reporting  for  treatment.  Syphilis  has  been 
reduced  from  about  20  cases  annually  to  one  case  for  the  entire  year 
1910,  and  this  patient  did  not  report  for  prophylactic  treatment.     The 

^"The  Social  Evil  in  Chicago."  Report  by  the  Vice  Committee,  1911.  "Pros- 
titution in  Europe,"  Abraham  Fle.Kner    (The  Century  Co.),   1914. 

^Ledbetter,  Robert  E.,  "Venereal  Prophylaxis  in  the  U.  S.  Navy,"  Jour. 
A.  M.  A.,  April  15,  1911,  Vol.  LVI,  No.  15,  p.  1098. 


68  JJJ8KASES  HAVINC  SP-KCJIAIv  TIJOPHYLAXIS 

results  speak  for  themselves  and  show  tlie  efficiency  ol'  the  i>ioj)hylactic 
measures  if  properly  and  thoroughly  carried  out. 

Holcomb  and  Gather  ^  report  the  following  as  a  result  of  treatment 
used  by  them  in  3,268  persons  in  the  U.  S.  Navy  between  May  1,  1910, 
and  August  31,  1911.  The  experience  is  considered  to  be  a  fair  index 
of  the  results  of  medical  prophylaxis.  The  treatment  used  by  them 
is  as  follows:  (1)  Wash  the  penis,  head,  shank,  and  under  frenum  with 
1-5,000  bichlorid  of  mercury  solution  with  a  cotton  sponge.  (2)  Pass 
water.  Take  urethral  injection  of  2  per  cent,  protargol  solution  and 
hold  to  count  GO.  (3)  Eub  50  per  cent,  calomel  ointment  well  into 
foreskin,  head,  and  shank  of  penis,  with  particular  care  about  the  fre- 
num. Treatment  taken  within  eight  hours  after  exposure  in  1,385 
cases  shows  19  infections,  or  but  1.37  per  cent.  In  the  interval  of 
from  eight  to  twelve  hours  after  exposure  in  741  cases  shows  25  infec- 
tions, or  3.31  per  cent.  Between  twelve  and  twenty-four  hours  in  920 
cases  shows  4G  infections,  or  5  per  cent.  Of  the  56  cases  of  gonorrhea 
occurring  in  the  first  twenty-four-hour  interval,  26  were  recurrent  cases; 
the  remaining  30  were  primary  infections. 

The  use  of  salvarsan  early  in  syphilis  will  prevent  the  further  spread 
of  the  infection. 

Segregation. — Theoretically,  every  case  of  syphilis  or  gonorrhea 
should  be  isolated  until  the  danger  of  infection  is  passed.  Practically, 
however,  segregation  is  impracticable  except  with  a  limited  number  of 
cases.  With  better  and  more  attractive  hospital  facilities  and  free  beds 
a  certain  amount  of  segregation  may  be  accomplished  voluntarily  and 
humanely.  An  alert  health  officer  can  trace  the  source  of  infection  in 
certain  cases  and  induce  the  women  responsible  to  take  the  salvarsan 
treatment  in  the  case  of  syphilis,  or  to  submit  to  hospital  care  in  the 
case  of  gonorrhea  or  chancroid. 

Pontine  circumcision  and  a  medical  examination  as  a  necessary  pre- 
liminary to  marriage  are  further  hygienic  reforms  advocated. 

Finally,  in  considering  venereal  prophylaxis,  it  should  be  remem- 
bered that  these  diseases  are  of  great  antiquity  and  seem  likely  to  con- 
tinue indefinitely,  that  they  already  affect  a  large  number  of  the  popu- 
lation, and  are  spreading;  that  the  existing  means  for  the  treatment 
of  them  among  the  poor  is  insufficient ;  that  the  common  mode  of  propa- 
gation is  irregular  and  illicit  intercourse;  that  prostitution  arose  in 
response  to  the  strongest  instincts  and  passions  in  the  human  breast; 
and  that  prostitutes  themselves  need  protection  and  have  claims  on 
the  humanity  of  the  law.  Furthermore,  Lecky  thinks  that  "The  prosti- 
tute is  ultimately  the  efficient  guardian  of  virtue."' 

>  Holcomb,  Pv.  C,  and  Gather,  D.  C.  U.  S.  X..  "Study  of  3,268  Venereal 
Prophylactic  Treatments,"  Jour.  A.  M.  A.,  Vol.  LVIII,  No.  5,  Feb.  3,  1912,  p.  368. 


PEEVENTABLE   BLIXDXESS  69 


PREVENTABLE  BLINDNESS 

Preventable  blindness  is  considered  in  this  place  because  the  largest 
single  factor  causing  needless  loss  of  eyesight  is  gonorrhea.  Among 
the  infectious  eye  troubles  the  most  destructive  is  ophthalmia  neona- 
torum. 

There  are  64,000  registered  blind  persons  in  the  United  States.  Of 
these  about  10  per  cent,  (between  six  and  seven  thousand)  are  blind 
as  the  result  of  ophthalmia  neonatorum.  From  25  to  30  per  cent,  of  all 
the  blind  children  in  all  the  blind  schools  of  this  country  owe  their 
infliction  to  gonorrhea.  It  has  been  estimated  that  probably  one-half 
of  the  blindness  in  the  world  is  preventable. 

Emphasis  upon  the  great  harm  done  by  ophthalmia  neonatorum 
should  not  blind  us  to  the  fact  that  there  are  other  causes  of  blindness 
and  eye  deterioration  which  are  preventable;  thus  we  have  to  consider 
the  later  pus  infections,  also  syphilis,  smallpox,  leprosy,  sympathetic  in- 
flammations, industrial  accidents,  accidents  at  play,  progressive  near- 
sightedness caused  by  violation  of  ocular  hygiene,  and  a  variety  of 
inflammatory  conditions.  Functional  disturbances  of  vision  (amaurosis) 
and  atrophy  of  the  optic  nerve  may  be  brought  about  by  poisoning  with 
lead,  alcohol,  tobacco,  and  other  toxic  substances.  This  form  of  dimness 
of  vision,  or  even  loss  of  sight,  occurs  rather  frequently,  and  in  most 
instances  is  preventable. 

One  of  the  common  causes  of  impaired  sight  is  phlyctenular  keratitis, 
which  leaves  scars  on  the  cornea.  This  condition  is  associated  witli 
tubercular  glands  of  the  neck  and  is  probably  a  form  of  bovine  tubercu- 
losis, hence  preventable. 

Trachoma  is  a  menace  to  the  integrity  of  sight.  It  is  an  infection 
caused  by  a  virus,^  which  is  destroyed  by  heating  for  3  minutes  at  50°  C. ; 
it  may  be  preserved  in  glycerin  7  days.' 

The  filtrability  of  the  virus  of  trachoma  remains  undetermined.  Ex- 
perimental evidence  permits  no  more  than  the  suspicion  that  the  virus 
may  be  filtrable  under  some  circumstances.^  In  1907  Prowaczek  *  de- 
scribed the  so-called  inclusion  or  trachoma  bodies.  The  nature  of  these 
bodies  and  their  possible  etiologic  relation  to  trachoma  still  remain  un- 
determined.    Lindner  ^  described  another  form  of  these  bodies  but  this 

^  Bertarelli  and  Cacchetto,  Cfentr.  fur  Bait.,  Orig.,  I  Abt.,  Bd.  XLVIII,  1908, 
p.  432,  and  Pathologica,  107,  p.  1088,  April  15,  1908. 

^Nicolle,  Cuenod  and  Blaizat,  Comptes  Rendu  Acad.  Sci.,  CLVI,  April  14, 
1913,  p.  1177. 

^Jour.  A.  M.  A.,  LXIV,  No.   12,  Mar.  20,  191.5,  p.  1000. 

*  Halberstildter  and  Prowaczek,  Deut.  med.  Wochenschr.,  1007,  XXXIIT, 
128,5,  Arb.  a.  d.  k.  (lesundheitsamte,  1907,  XXVI.  44. 

^  "Die  freie  Initialform  der  P.  Einschliisse,"  Wien.  Mm.  Wochenschr.,  1909, 
XLIX,  1697:   Arch.  f.  Ophth..  1910,  LXXVI,  559. 


70  DISEASES  HAVINO  SPECIAL  PROPHYLAXIS 

has  added  little  to  our  knowledge,  Noguclii  and  ('ohcn  ^  have  recently, 
1913,  reported  the  successful  cultivation  of  these  Jnclusion  Ijodie.s,  hut 
since  the  cultivated  bodies  proved  non-pathogenic  the  questi(ni  still 
remains  an  open  one. 

Trachoma  flourishes  best  where  sanitary  conditions  are  worst.  I'he 
control  of  trachoma  consists  in  eliminating  the  foci  of  the  disease,  im- 
proving personal  hygiene,  and  community  sanitation.  The  disease  is 
slow  and  insidious  in  its  development.  A  mass  of  sago-lilce  granulati(jns 
gradually  fills  in  the  retrotarsal  fold,  therel)y  limiting  the  lid  movements 
and  leaving  the  eye  half  closed.  The  infection  is  rul)bed  into  the  eye  by 
roller  towels,  handkerchiefs,  fingers,  and  other  ways.  When  once  estab- 
lished, the  disease  is  chronic,  and  permanent  cures  are  doubtful. 

Trachoma  is  much  more  prevalent  in  the  United  States  than  is  ordi- 
narily supposed.  The  public  eye  clinics  of  Chicago  are  filled  with  pa- 
tients showing  the  resulting  deformities.  Wilder  located  a  center  in 
southern  Illinois,  and  it  has  also  been  found  in  the  mountains  of  Ken- 
tucky and  Tennessee,  while  in  Oklahoma  this  disease  has  become  a  public 
menace. 

It  is  more  or  less  prevalent  in  the  poorer  sections  of  all  the  larger 
centers. 

Trachoma  is  of  such  a  serious  nature  that  all  immigrants  arriving  at 
our  shores  have  their  eyelids  everted  and  conjunctivae  examined  for 
evidence  of  this  infection.  An  alien  with  trachoma  is  deported  and  the 
steamship  is  liable  to  a  fine  of  one  hundred  dollars  for  bringing  every 
ease  of  trachoma  where  it  can  be  shown  that  the  disease  might  have 
been  recognized  at  the  port  of  departure. 

Wood  alcohol,  Columbian  spirits,  methyl  alcohol  (CH^OH),  cause 
blindness  through  atrophy  of  the  optic  nerves.  As  small  a  quan- 
tity as  a  teaspoonful  has  caused  loss  of  vision.  Blindness  may  even  be 
caused  by  inhaling  the  vapor.  Quantities  as  small  as  0.2  per  cent,  in  the 
inspired  air  may  accumulate  in  the  body  and  cause  toxic  effects.  Wood 
alcohol  is  used  as  an  adulterant,  especially  in  liquors. 

Accidents. — In  New  York  State  about  200  industrial  accidents  re- 
sulting in  total  blindness  occur  annually.  Besides  this,  there  are  a  large 
number  of  accidents  occurring  on  railroads  in  construction  work,  and  in 
the  field  and  forest. 

Many  of  the  accidents  to  the  eyes  occurring  in  factories  are  pre- 
ventable. As  a  rule,  the  majority  of  such  accidents  are  due  to  small 
flying  particles. 

A  material  proportion  of  blindness  is  caused  by  accidents  to  chil- 
dren at  play;  sometimes  the  eyeball  is  torn  by  a  buttonhook  or  pierced 
by  a  knife  or  awl ;  or  a  scissors  blade,  used  to  untie  a  knot,  slips.     Some 

^  "Experiments  on  Cultivation  of  So-called  Trachoma  Bodies,"  Jour.  Exp. 
Med.,  1913,  XVIII,  No.  5. 


PEEVENTABLE   BLINDNESS  7.1 

eyes  have  been  injured  by  the  crack  of  a  whip,  by  a  shot  from  an  air-gun 
or  toy  pistol.  Accidents  also  occur  to  the  eyes  from  fireworks,  especially 
on  the  Fourth  of  July. 

Ocular  Hygiene,  see  page  706. 

OPHTHALMIA  NEONATORUM 

Ophthalmia  neonatorum  or  inflammation  of  the  eyes  of  the  new- 
born includes  all  the  inflammatory  conditions  of  the  conjunctiva  that 
occur  shortly  after  birth — usually  before  the  end  of  the  first  month. 
The  conjunctivae  of  the  newborn  are  peculiarly  liable  to  infections.  This 
delicate  membrane  rapidly  acquires  an  immunity  of  a  high  order.  The 
gonococcus  is  usually  the  cause  of  severe  conjunctivitis  occurring  in 
a  baby  a  few  days  old.  The  gonococcus  has  been  demonstrated  in  65 
per  cent,  of  all  cases,  mild  and  severe. 

Ophthalmia  neonatorum  is  not  always  gonorrheal,  but  may  be  pro- 
duced by  other  virulent  microorganisms  or  by  irritating  substances. 
The  microorganisms  other  than  the  gonococcus  that  sometimes  cause 
conjunctivitis  during  the  early  days  of  life  are :  streptococci,  the  menin- 
gococcus, the  Koch- Week's  bacillus,  the  pneumococcus,  the  diphtheria 
bacillus,  and  even  staphylococci.  These  are  relatively  so  rare  that  we 
may  disregard  their  etiological  significance  for  our  present  purpose. 
The  diagnosis  of  gonorrheal  ophthalmia  may  readily  be  made  by  simply 
examining  a  stained  smear  of  the  secretion. 

The  infection  commonly  occurs  during  the  passage  of  the  child 
through  the  genital  tract  of  the  mother  and  usually  just  before  deliv- 
ery. It  is  caused  by  the  entrance  of  the  vaginal  secretion  containing 
gonococci  into  the  conjunctival  sac.  It  may  also  be  caused  after  de- 
livery by  infected  hands,  towels,  sponges,  or  other  objects. 

The  disease  varies  in  severity;  sometimes  it  is  very  mild,  with  slow 
onset  and  spontaneous  recovery.  Usually,  however,  it  is  severe  and 
serious.  The  inflammation  may  extend  from  the  conjunctiva  to  the 
cornea  and  invade  the  deeper  structures  of  the  eye.  Corneal  .ulcers 
and  opacity  may  result,  with  complete  loss  of  vision.  In  a  typical 
case  both  the  ocular  and  palpebral  conjunctivae  are  red  and  very  much 
swollen;  the  eyelids  and  surrounding  tissues  are  infiltrated  and  there 
is  a  thick,  creamy,  abundant  secretion. 

There  are  many  grades  of  mild  inflammatory  condition,  which  must 
not  be  mistaken  for  gonorrhea.  At  birth  the  eyelids  are  almost  always 
glued  together  with  a  normal  sticky  secretion.  It  is  common,  too, 
for  the  lids  to  remain  red  and  sticky  for  a  day  or  so.  The  diagnosis 
may  be  made  in  a  few  minutes  by  a  microscopic  examination. 

Prevalence. — Kerr  calls  attention  to  the  fact  that  there  are  no  com- 
plete statistics  showing  the  prevalence  of  ophthalmia  neonatorum,  and 
only  an  approximate  idea  can  be  had  of  the  number  of  cases  by  study- 


73  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

iiig  the  admissions  to  schools  for  tlio  blind.  A  committee  of  the  Brit- 
ish Medical  Association  found  that  more  than  one-third  of  those  in 
blind  schools  of  Great  Britain  owed  their  affliction  to  this  disease.^ 

In  the  United  States  and  Canada,  in  1907,  out  of  234  admissions 
to  10  schools  for  the  blind,  59,  or  24.38  per  cent.,  were  blind  as  a  result 
of  ophthalmia  neonatorum;-  and  out  of  351  admissions  to  certain 
schools  in  the  United  States  and  Canada  in  1910,  84,  or  23.9  per  cent., 
were  blind  from  this  cause.^ 

As  a  result  of  studies  made  of  ophthalmia  neonatorum  in  10  man- 
ufacturing cities  of  Massachusetts,  Greene  has  presented  figures  which 
show  that  the  minimum  morbidity  rate  for  this  disease  was  G.4  per 
1,000  births.  A  more  complete  census  made  by  him  from  the  practice 
of  173  physicians  in  9  cities  revealed  an  average  morbidity  rate  of 
10.8  per  1,000  births.* 

It  is  estimated  that  the  total  annual  loss  from  gonorrheal  ophthalmia 
in  the  United  States  is  seven  million  dollars,  and  that  more  than  one 
million  dollars  annually  is  spent  in  partially  caring  for  its  victims.  A 
blind  child  costs  the  community  an  excess  of  about  $4,500  for  its 
schooling. 

Prevention. — Ceede's  Method. — Crede  in  1881  introduced  an  effi- 
cient method  of  preventing  ophthalmia  neonatorum  at  the  Lying-in 
Hospital  at  Leipzig,  thereby  connecting  forever  his  name  with  the  pre- 
vention of  the  disease  and  the  subsequent  saving  of  the  sight  of  many 
infants.  Crede's  original  method  consisted  sim^jly  in  placing  one  or 
two  drops  of  a  2  per  cent,  solution  of  silver  nitrate  in  each  conjunctival 
sac,  as  soon  as  practicable  after  the  birth  of  the  head. 

In  order  to  prevent  gonococcic  as  well  as  other  infections  of  babies' 
eyes,  the  following  procedure  is  recommended :  During  pregnancy 
women  should  be  instructed  to  practice  daily  external  cleansing  with 
soap  and  water  and  a  clean  wash-cloth.  In  case  of  any  irritating  dis- 
charge or  even  profuse  white  discharge,  a  physician  should  at  once  be 
consulted. 

Immediately  after  labor  the  eyelids  should  be  carefully  cleaned  with 
sterile  absorbent  cotton  or  gauze  and  a  saturated  solution  of  boracic 
acid.  A  separate  pledget  should  be  used  for  each  eye  and  the  lids 
washed  from  the  nose  outward  until  quite  free  of  all  mucus,  blood,  or 
meconium  without  opening  the  lids.  Next  the  lids  should  be  separated 
and  one  or  two  drops  of  a  1  per  cent,  silver  nitrate  solution  should  be 
dropped  into  each  eye,  between  the  outer  ends  of  the  lids.  The  lids  should 
be  separated  and  elevated  away  from  the  eyeball  so  that  a  lake  of  silver 

^British  Medical  Journal,  May  8,  1909. 
'Jour.  A.  M.  A.,  May  23,  1909,  p.  1745. 
^Jour.  A.  M.  A.,  July  1,  1911,  p.  72. 

*  Monograph  Series  of  the  American  Association  for  Conservation  of  Vision, 
Vol.  I,  No.  1. 


PREVENTABLE   BLINDNESS  73 

nitrate  solution  may  lie  for  one-half  minute  or  longer  between  them, 
coming  in  contact  with  every  portion  of  the  conjunctival  sac.  One 
application  only  of  the  silver  nitrate  should  be  made,  and  ordinarily 
no  further  attention  need  be  given  to  the  eyes  for  several  hours.  Each 
time  the  child  is  bathed  the  eyes  should  first  be  wiped  and  cleaned  with 
pledgets  of  sterile  absorbent  cotton  wet  with  a  saturated  solution  of 
boracic  acid. 

Crede  used  a  2  per  cent,  solution  of  silver  nitrate,  but,  as  this  is 
sometimes  irritating,  a  1  per  cent,  solution  is  now  commonly  employed, 
and  seems  to  afford  equally  efificient  prophylaxis.  The  silver  nitrate 
solution  should  be  instilled  into  each  conjunctival  sac  but  once.  Re- 
located applications  may  cause  serious  inflammations.  In  fact,  a  single 
treatment  sometimes  causes  a  conjunctivitis,  known  as  "silver  catarrh.'' 
Because  of  the  silver  catarrh  the  strength  of  the  silver  nitrate  solution 
has  not  only  been  reduced  from  a  3  to  a  1  per  cent,  solution,  but  this 
may  be  neutralized  after  instillation  with  salt  solution.  Other  prophy- 
lactic substances  have  been  proposed.  The  best  substitutes  are  a  few 
drops  of  the  newer  silver  compounds,  as  argyrol  (25  per  cent.)  or 
protargol  (5  per  cent.).  The  following  have  also  been  recommended: 
Bichlorid  of  mercury,  1-3,000  or  1-5,000,  silver  acetate,  0.33  per  cent., 
recommended  by  Zweifel,  who  used  it  in  5,333  cases.  Schmidt  and 
Rimpler  recommend  aqua  chlorini.  Carbolic  acid  (1  per  cent.)  or  other 
antiseptics  have  also  been  tried.  No  substance,  however,  is  known  to 
be  as  reliable  as  silver  nitrate,  which  should  be  used  in  all  cases  where 
there  is  any  reason  for  believing  that  the  mother  is  infected  with  the 
gonocoecus. 

If  a  conjunctivitis  is  present,  a  bacteriological  examination  of  the 
discharge  should  at  once  be  made.  If  the  inflammation  is  due  to  the 
gonocoecus  a  8  per  cent,  silver  nitrate  solution  should  be  used.  In  cer- 
tain mild,  non-gonorrheal  infections  0.5  per  cent,  is  usually  sufficient. 
If  the  Klebs-Loeffler  bacillus  is  found,  diphtheria  antitoxin  should  be 
given  without  delay.  If  the  diplococcus  is  present,  a  weak  solution 
(1  grain  to  the  ounce)  of  zinc  sulphate  should  be  instilled  frequently. 

As  a  general  rule,  it  is  advisable  to  use  a  prophylactic  as  a  mat- 
ter of  routine  in  hospital  and  private  practice.  To  use  Crede's  method 
upon  every  case  necessitates  the  unpleasant  suspicion  that  every  woman 
is  a  possible  source  of  gonocoecus  infection.  If  statements  of  the  father 
about  his  previous  life  can  be  relied  upon,  an  eye  prophylactic  can  be 
safely  omitted.  In  his  private  work  Williams  uses  a  boric  acid  solution 
except  where  there  is  special  reason  for  believing  that  the  mother  has 
gonorrhea.  The  responsibility  for  risking  the  baby's  eyes  rests  upon 
the  medical  attendant.  There  can  only  be  one  safe  rule  in  case  of 
doubt.  It  should  be  remembered  that  gonococcic  infections  of  the  con- 
junctiva occur  in  about  one  to  every  two  hundred  births  (Edgar). 


74  DISEASES  HAVING  SPECIAL  PROPHYLAXIS 

The  good  results  of  Crede's  metliod  arc  sndicionlly  convincing  to 
justify  criminal  proceedings  upon  those  who  fail  to  apply  this  simple 
prophylactic.  liaab  reduced  the  frequency  of  ophthalmia  neonatorum 
in  hospital  practice  from  9  to  1  per  cent.,  while  the  statistics  of  many 
hospitals  show  only  a  very  small  fraction  of  1  per  cent.  Stephenson's 
results  are  typical.  In  2,265  births,  ophthalmia  neonatorum  developed 
in  10  per  cent,  of  the  cases  preceding  the  use  of  Crede's  method.  In 
1,160  births  after  this  method  only  0.17  per  cent,  developed  any 
trouble.  A  small  number  of  cases  may  develop  despite  the  use  of  silver 
nitrate. 

The  technic  of  applying  the  nitrate  of  silver  is  very  important,  for, 
in  the  opinion  of  Edgar,  when  ophthalmia  neonatorum  develops  after  the 
use  of  nitrate  of  silver,  it  is  due  either  to  a  secondary  infection  or  to 
the  fact  that  the  solution  does  not  really  bathe  the  mucous  membranes, 
but  remains  upon  the  lashes.  The  lids  must  be  everted  and  the  silver 
solution  placed  in  the  conjunctival  sac  either  from  a  glass  rod  or  a 
pipette.  Care  must  be  taken  not  to  touch  or  injure  the  delicate  mem- 
brane. 

Crede's  method  does  not  strike  at  the  root  of  the  evil.  It  would, 
of  course,  be  much  better  to  eradicate  gonorrhea  from  men  and  women 
than  to  be  compelled  to  drop  silver  nitrate  into  babies'  eyes.  Wrapped 
up  wdth  the  question  of  ophthalmia  neonatorum  is  the  question  of 
midwives,  for  to  prevent  blindness  we  must  have  intelligent  and  con- 
scientious obstetrical  attendants,  especially  for  the  poor  and  ignorant 
classes.  Midwifery  practice  needs  regulation,  supervision,  and  eleva- 
tion. Education  is  one  of  the  bulwarks  of  prevention  in  this  as  well 
as  other  preventable  infections. 

Legislation. — Ophthalmia  neonatorum  is  an  instance  in  which  "the 
protection  of  the  citizen  from  the  assaults  of  ignorance,  indifference, 
or  neglect,  wdien  they  threaten  his  well-being  and  even  his  economic 
efficiency,  is  a  duty  which  the  state  cannot  evade  and  which  he  has  a 
right  to  exact." 

Laws  for  the  prevention  of  the  blindness  of  newborn  infants  are 
making  progress  slowly.  Among  the  states  in  which  the  disease  is 
notifiable  are  Connecticut,  Massachusetts,  Minnesota,  Nebraska,  New 
York,  Oregon,  South  Carolina,  Utah,  Vermont,  and  Wisconsin.  In 
some  states  the  nurse,  midwife,  or  parent  is  required  to  report  the  dis- 
ease, in  other  states  the  attending  physician. 

Maine  was  the  first  state  to  take  legal  steps  in  1891  to  control 
ophthalmia  neonatorum.  In  1892  New  York  followed,  with  an  amend- 
ment to  the  law  relative  to  midwives  and  nurses.  Subsequently  most  of 
the  other  states  took  legislative  action.^     The  provisions  of  the  several 

^Kerr,  J.  W.,  "OpTithalmia  Neonatorum:  An  Analysis  of  the  Laws  and  Reg- 
ulations Relating  Thereto  in  Force  in  the  United  States,"  Fublio  Health  Bull. 
Ko.  49,  U.  S.  P.  H.  &  M.  H.  S.,  Oct.,  1911. 


TETAXUS  75 

]a\vs  are  quite  varied.  In  all  of  them,  however,  the  object  is  to  insure 
early  treatment,  and  to  this  end  compulsory  notification  is  generally 
required.  The  health  authorities  of  Massachusetts,  New  Jersey,  Ver- 
mont, lihode  Island,  New  York,  and  the  District  of  Columbia  furnish 
jDrophylactic  outfits  to  physicians.  The  outfit  ordinarily  consists  of  a 
small  vial  containing  a  1  per  cent,  solution  of  nitrate  of  silver,  a  steri- 
lized dropper  and  bulb,  and  a  circular  of  instructions. 

In  order  to  make  material  progress  against  ophthalmia  neonatorum, 
as  well  as  against  infant  mortality,  it  is  essential  that  laws  require 
prompt  report  of  all  births;  it  is  the  duty  of  the  health  authorities  to 
see  to  it  that  such  laws  are  efi^ectively  carried  out.^ 


TETANUS 

Compared  with  the  major  plagues  of  man,  lockjaw  has  always  been 
a  rare  disease.  It  is  on  account  of  the  characteristic  and  fatal  spasms 
that  it  early  attracted  attention.  The  student  will  be  M^ell  repaid  by 
a  study  of  the  historical  development  of  the  theories  that  have  been 
advanced  since  the  time  of  Hippocrates  to  explain  the  cause  of  tetanus. 
These  theories  mirror  the  prevailing  thought  upon  the  nature  of  dis- 
ease as  it  developed  from  that  of  evil  spirits,  through  the  humoral 
theory,  the  realm  of  miasms  and  noxious  effluvia,  to  the  germ  theory. 
Tetanus  could  not  escajDe  the  rheumatism  theory  which  has  been  such 
an  alluring  catchall  for  symptoms  and  diseases  difficult  of  explanation. 
"Taking  cold"  was  assigned  its  usual  role  here  as  elsewhere.  When  no 
assignable  cause  seemed  at  hand,  the  disease  was  given  the  learned 
title — idiojjathic  tetaniis. 

Etiology. — In  1889,  with  the  aid  of  anaerobic  technic,  Kitasato  ^ 
for  the  first  time  grew  the  tetanus  bacillus  in  pure  culture,  and  by 

^  The  Massachusetts  law  reads  as  follows : 

Section  49.  .  .  .  Should  one  or  both  eyes  of  an  infant  become  inflamed^ 
swollen  and  red,  and  show  an  unnatural  discharge  at  any  time  within  two  weeks 
after  its  birth,  it  shall  be  the  duty  of  the  nurse,  relative,  or  other  attendant 
having  charge  of  such  an  infant  to  report  in  writing  within  six  hours-thereafter, 
to  the  board  of  health  of  a  city  or  town  in  which  the  parents  of  the  infant 
reside,  the  fact  tliat  such  infiammation,  swelling,  and  redness  of  the  eyes  and 
unnatural  discharge  exist.  On  receipt  of  such  report,  or  of  notice  of  tlie  sann; 
symptoms  given  by  a  physician  as  provided  by  the  following  section,  the  board 
of  health  shall  take  such  immediate  action  as  it  may  deem  necessary  in  order 
that  blindness  may  be  prevented.     Whoever  violates  the  provision's  of  this 

SECTION   SHALL  BE  PUNISHED  BY  A  FINE  OF  NOT  MORE  THAN   ONE  HUNDRED  DOLLARS. 

Section  50.  ...  If  a  physician  knows  that  ...  if  one  or  both  eyes 
of  an  infant  whom  or  whose  mother  he  is  called  to  visit  become  inflamed,  swollen, 
and  red,  and  show  an  unnatural  discharge  within  two  weeks  after  birth  of  such 
infant,  he  shall  immediately  give  notice  thereof  in  writing  over  his  own  signa- 
ture to  the  selectmen  or  board  of  health  of  the  town;  and  if  he  refuses  or  neg- 
lects   TO   GIVE   SUCH   NOTICE,   HE    SHALL   FORFEIT   NOT   LESS   THAN   FIFTY   NOR   MORE 

THAN  TWO  HUNDRED  DOLLARS  FOR  EACH  OFFENCE.     (Revised  Laws,  Chapter  75.) 
^ZeitsGhr.  f.  Hyg.,  Vol.  VII,  1889,  p.  225. 


76  DISEASES  HAVING  SPECIAL  I'KOI'll  YLAX  IS 

successful  inoculation  experiments  pyoxcd  tJiat  tlii.s  hacilliis  was  tlie  real 
cause  of  tetanus.  Kitasato  further  .showed  tiiat  tlie  tetanus  ha(,-ilhi.s  is 
not  found  in  the  heart's  hlood  of  mice  dead  of  tcstanus,  and  therefore 
concluded  that  we  are  dealing  with  an  intoxication,  and  not  an  infec- 
tion. We  now  regard  tetanus  as  a  type  of  the  true  toxemias.  This 
work  of  Kitasato's  was  one  of  great  importance,  and  led  up  to  the  epoch- 
making  discovery  of  Behring  and  Kitasato  ^  in  the  following  year  (1890) 
upon  tetanus  anxl  diphtheria  toxins  and  antitoxins,  laying  the  founda- 
tion of  serum  therapy. 

Tetanus  may  he  regarded  almost  solely  as  a  wound  complication. 
All  wounds  are  not  equally  liahle  to  this  complication,  even  though 
tetanus  spores  are  present.  Punctured,  lacerated,  and  contused  wounds 
are  much,  more  susceptible  to  tetanus  than  cleancut  or  superficial  wounds. 
The  size  of  the  wound  is  of  much  less  consequence  than  its  character. 
Fatal  tetanus  may  develop  from  trivial  wounds,  such  as  pin  scratches, 
small  splinters,  insect  bites,  vaccinations,  etc. 

Symbiosis  is  an  important  factor  in  tetanus.  Wounds  infected  with 
pyogenic  organisms  and  other  bacteria  favor  anaerobic  conditions  and 
permit  the  tetanus  spores  to  germinate,  and  seem  to  encourage  the 
growth  of  the  bacillus  and  the  development  of  toxin. ^  A  few  tetanus 
spores  free  of  tetanus  toxin  in  a  clean  wound  may  be  taken  care  of  by 
the  phagocytic  cells.  This  may  readily  be  demonstrated  experimentally 
by  injecting  animals  with  tetanus  spores  washed  free  of  toxin. 

The  normal  habitat  of  tetanus  is  in  the  intestinal  tract  of  herbiv- 
orous animals.  Sanchez,  Toledo,  and  Veillon  ^  found  tetanus  in  the 
feces  of  4  out  of  6  horses  and  in  the  feces  of  1  of  2  cows.  Park  found 
tetanus  bacilli  in  the  intestines  of  about  15  per  cent,  of  horses  and 
calves  living  in  the  vicinity  of  New  York  City.  They  are  present  to 
a  variable  extent  in  the  intestines  of  other  animals  and  of  man. 

It  is  rather  a  curious  paradox  that  the  horse,  which  is  the  most 
susceptible  of  all  animals  to  tetanus  toxin,  is  one  of  the  principal  hosts 
of  the  tetanus  bacillus.  The  intestinal  contents  of  certain  animals  offer 
^particularly  favorable  conditions  for  the  growth  of  tetanus  bacillus ;  such 
animals  may  be  regarded  as  "tetanus  carriers." 

The  spores  taken  in  the  food  are  not  affected  by  gastric  digestion, 
and  in  the  small  intestines  find  ideal  anaerobic  conditions,  food  supply 
and  temperature  for  growth  and  development.  Here  they  may  multiply 
and  pass  in  the  dejecta  to  pollute  the  soil.  The  soil,  therefore,  in  all 
regions  inhabited  by  man  and  domestic  animals  is  more  or  less  contami- 
nated with  tetanus.  The  bacilli,  however,  do  not  multiply  in  the  soil. 
While  the  soil  acts  only  as  a  vehicle,  it  is  the  immediate  source  of  the 

^Deutsch.  med.  Wochcns.,  Vol.  XVI,  No.  40,  p.  1113. 

^  In  tlie  laboratory  some  of  the  strongest  tetanus  toxins  have  been  prepared 
from  mixed  or  contaminated  cultures. 
^La  Semame  Med.,  1890,  X,  p.  45. 


TETANUS  77 

large  proportion  of  tetanus  in  man.  Tiio  proscnee  of  tetanus  spores  in 
soil,  street  dust,  fresli  vegetables  and  on  clothing  and  the  skin  may  be 
traced  to  fecal  contamination. 

On  account  of  the  great  resistance  of  the  spores,  they  are  blown  about 
in  dust  and  are  spread  everywhere  by  dirt  and  manure.  Tetanus 
has  been  found  in  hay  dust,  on  horses'  hair,  in  the  dust  of  houses,  bar- 
racks, and  hospitals,  in  the  mortar  of  old  masonry,  in  street  dust,  in 
gelatin,  and  in  the  greatest  variety  of  places. 

One  of  the  agencies  in  the  distribution  of  tetanus  spores  over  lim- 
ited areas  is  undoubtedly  the  common  house  fly.  The  poisoned  arrow- 
heads of  certain  savages  in  the  Xew  Hebrides  contain  tetanus  spores 
obtained  by  smearing  the  arrowheads  with  dirt  from  crab  holes  in  the 
swamps  (Le  Dantic). 

Tetanus  bacilli  are  not  equally  numerous  in  all  localities.  The  in- 
fection is  much  more  prevalent  in  warm  than  in  cold  countries.  It  is 
especially  severe  in  the  tropics,  yet  Iceland  at  one  time  sutfered  severely 
from  tetanus  neonatorum.  Some  parts  of  Long  Island  and  Xew  Jersey 
have  become  noticeable  for  the  number  of  cases  of  tetanus  complicating 
small  wounds.  Tetanus  spores  are  widely  disseminated  in  India.  Good- 
rich states  that  in  Bombay  alone  there  were  1,955  cases  of  tetanus  in 
five  years.     These  do  not  include  the  jjuerperal  cases. 

Tetanus  occurs  eitlier  sporadically  or  in  epidemic  form.  Formerly 
epidemics  in  hospitals  (especially  in  lyi]ig-in  liospitals)  and  in  wars 
were  rather  common.  The  conditions  of  trench  M'arfare  now  going  on 
favor  wound  complication,  including  a  frightful  amount  of  tetanus. 
Before  the  days  of  antisepsis  the  infection  was  readily  spread  through 
instruments,  fingers,  bandages,  etc. 

Trismus  neonatorum,  or  tetanus  of  the  newborn,  was  a  common  and 
very  fatal  infection,  especially  in  the  tropics.  Before  the  days  of 
asepsis  the  infection  was  permitted  to  enter  through  the  umbilical 
wound.  In  certain  of  the  West  Indian  islands  more  than  one-half  of 
the  mortality  among  the  negro  children  has  been  due  to  this  cause. 
Since  the  introduction  of  proper  methods  of  treating  the  cord  the 
disease  is  rare. 

The  wounds  produced  by  blank  cartridges  are  especially  liable  to 
develop  tetanus.  The  source  of  the  tetanus  spore  in  these  cases  is  not 
entirely  clear.  Wells  examined  200  cartridges  from  five  firms  without 
finding  the  tetanus  bacillus.  It  is  probable  that  the  spore  is  upon  th€ 
skin  and  is  carried  along  with  the  paper  and  powder  from  the  blank 
cartridge.  The  peculiar  character  of  the  wound  favors  the  develop- 
ment of  tetanus. 

The  great  decrease  in  the  number  of  cases  of  tetanus  following 
Fourth  of  July  wounds  is  due  to  the  vigorous  campaign  carried  on 
by  the  American  Medical  Association.     In  1903  there  were  40G  deaths 


78  DTSP]ASES  HAVING  SIM^XUAI.  I'llOl'll  VLAX  IS 

from  tetanus;  in  1904,  91;  1905,  87;  190G,  75;  3  907,  73;  1908,  70; 
and  in  1911  only  18  cases  and  10  deaths.  Eighty  per  cent,  of  these 
followed  blank  cartridge  wounds.  The  good  results  are  attributed  to 
the  more  thorough  and  careful  treatment  of  the  wounds  and  especially 
the  use  of  tetanus  antitoxin  as  a  prophylactic — and  more  recently  tti 
safer  and  saner  methods  of  celebration. 

Tetanus  spores  or  toxin  may  contaminate  bacterial  vaccines,  anti- 
toxic sera,  vaccine  virus,  and  other  biologic  products  used  in  human 
therapy.  The  possible  association  of  tetanus  with  bacterial  vaccines  A\'as 
demonstrated  in  the  unfortunate  outbreak  at  Mulkowal,  India,  in  190"i.^ 
One  hundred  and  seven  persons  were  inoculated  with  Haffkine's  plague 
prophylactic.  Of  these  19  were  affected  with  symptoms  of  tetanus  and 
died.  In  this  case  the  tetanus  probably  grew  as  a  contamination  in  the 
plague  culture,  for  it  is  now  well  known  that  the  anaerobic  conditions 
produced  in  B.  diphtJieriae,  B.  pestis,  B.  suhtilis,  and  other  organisms  in 
liquid  culture  media  favor  the  growth  of  tetanus  and  the  development 
of  its  toxin. 

In  St.  Louis  (1901)  diphtheria  antitoxin  was  taken  from  a  horse 
during  the  j^eriod  of  incubation  of  tetanus  and  used  in  amounts  from 
5  to  10  c.  c.  upon  7  children,  all  of  whom  died  of  tetanus.  Bolton, 
Fisch,  and  Walden  ^  found  that  the  serum  was  sterile,  but  contained 
tetanus  toxin  in  considerable  amount.  If  the  serum  had  first  been 
tested  upon  animals,  its  poisonous  properties  would  have  been  discov- 
ered. This  test  is  now  required  by  the  United  States  law  of  July  1, 
1903,  for  all  serums  and  vaccines  sold  in  interstate  traffic.  As  a  fur- 
ther precaution  against  this  complication  horses  undergoing  treatment 
for  the  production  of  immune  sera  are  given  prophylactic  doses  of  tet- 
anus antitoxin  from  time  to  time.  Tetanus  sometimes  occurs  as  a 
complication  of  vaccination  (see  page  22). 

It  is,  of  course,  not  the  rust  on  a  nail  that  is  dangerous,  so  far  as 
tetanus  is  concerned,  but  the  spore-bearing  dirt  it  carries  into  the  deep, 
contused  wound  that  causes  the  trouble.  Gelatin  may  contain  tetanus 
sjDores,  and  the  subcutaneous  injection  of  imperfectly  sterilized  gelatin 
as  a  hemostatic  has  sometimes  resulted  in  accidents. 

Tetanus  is  harmless  when  taken  by  the  mouth.  Susceptible  animals 
may  be  given  enormous  doses  of  tetanus  toxine  by  the  mouth  without 
producing  the  disease.  The  bacillus  and  its  spore  may  be  regarded  as 
a  saprophyte  in  the  intestinal  tract.  There  is,  however,  a  suspicion  that 
tetanus  spores  sometimes  invade  the  organism  through  small  wounds 
in  the  digestive  or  respiratory  tract.  Perhaps  some  of  the  cases  follow- 
ing surgical  operations  may  be  accounted  for  in  this  way  rather  than 
by  infection  of  the  catgut  used  for  ligatures. 

^Jour.  Trop.  Med.  and  Hyg.,  1907,  X,  p.  33. 

2  Bolton,  Fisch,  and  Walden  in  Ht.  Lovis  Medical  Revieiv,  Vol.  XLIV,  No.  21, 

Xov.  2?,.  inin.  p.  :^.(>i. 


TETANUS  79 

TctaiiiKS  sometimes  oeeurs  in  which  no  wound  can  be  found.  'I'liis 
is  the  so-called  "idiopathic  or  rheumatic  tetanus."  One  explaijatiou 
of  these  cases  is  to  be  found  in  the  fact  that  the  spores  are  numerous 
in  street  dust  and  may  enter  the  respiratory  tract.  They  cannot  do 
harm  so  long  as  the  mucous  membrane  is  healthy,  but  may  enter  through 
inflamed  memJbranes  or  through  small  vwunds  in  the  nose.  Tetanus 
bacilli  have  been  found  in  the  bronchial  mucus  of  idiopathic  cases.  Tet- 
anus spores  have  recently  been  found  in  the  lymph  glands,  liver,  and 
other  parts  of  the  body,  upsetting  our  previous  view  that  they  are  strictly 
confined  to  the  site  of  the  wound.  These  spores  may  remain  latent  for 
a  long  time,  awaiting  favorable  conditions  to  grow  and  produce  toxin, 
thus  giving  another  plausible  explanation  of  some  cases  of  idiopathic 
tetanus. 

Incubation. — The  period  of  incubation  in  man  is  usually  from  6  to 
14  days.  The  period  is  directly  proportional  to  the  amount  of  toxin  and 
the  severity  of  the  disease.  This  can  readily  be  demonstrated  upon 
susceptible  animals.  In  a  study  of  600  serial  tests,  Eosenau  and  Ander- 
son found  this  direct  relation  between  the  period  of  incubation  and  the 
severity  of  symptoms  by  the  subcutaneous  injection  of  varying  amounts 
of  toxin  into  guinea-pigs.  Thus,  guinea-pigs  receiving  fairly  large 
doses  showed  symptoms  on  the  third  day  and  usually  died,  a  very  small 
percentage  recovering.  The  smaller  the  dose  the  longer  the  period  of 
incubation  and  the  milder  is  the  disease,  and  the  greater  the  chances 
of  recovery.  With  a  short  period  of  incubation,  6  days  or  less,  the 
disease  in  man  is  almost  invariably  fatal.  With  longer  periods  the 
disease  is  milder  and  recovery  frequently  takes  place  without  the  use 
of  antitoxin  or  other  measures.  Tetanus  toxin  travels  up  the  axis  cylin- 
ders of  the  nerves  to  the  cord  and  brain.  It  is  also  distributed  in  the 
blood.  The  period  of  incubation,  therefore,  depends  somewhat  upon 
the  point  of  entrance  of  the  poison  and  its  proximity  to  large  motor 
nerve  endings. 

Resistance. — The  tetanus  bacillus  is  readily  destroyed  by  all  the  or- 
dinary agencies  that  kill  spore-free  bacteria.  It  is  killed  almost  at  once 
in  contact  with  the  free  oxygen  of  the  air.  On  the  other  hand,  few, 
if  any,  forms  of  life  have  a  greater  resistance  than  the  tetanus  spore. 
Hours  of  exposure  to  60°  or  70°  C.  do  not  affect  them.  They  usually 
survive  an  exposure  of  one  hour  to  80°  C,  but,  as  a  rule,  are  killed  in 
streaming  steam  or  boiling  water  in  60  minutes.  Tetanus  spores,  how- 
ever, vary  greatly  in  the  power  to  resist  the  boiling  temperature.  Ivita- 
sato  ^  found  them  to  resist  80°  C.  for  one  hour,  but  to  be  killed  in 
streaming  steam  in  5  minutes.  Vaillard  and  Vincent  ^  found  that  the 
spores  heated  in  the  presence  of  moisture  in  a  closed  vessel  would  resist 

^  Zeitschr.  f.  Hyg.,  VII.  p.  225. 

^  Ann.  de  I'lnst.  Pasteur,  18D1,  V,  p.  1. 


80  DISEASES  HAVINCt  SPECIAL  IMiOPHYLAXlS 

destruction  at  80°  C.  j'or  (i  liours,  at  90°  C.  for  )l  Jiolu'.s,  uud  100°  C. 
3  to  4  minutes,  that  they  were  not  always  destroyed  in  ■>  minutes,  hut 
never  resisted  more  than  8  minutes  at  100°  C.  Levy  and  Bruns  ^  found 
that  destruction  hcgins  at  81/^  minutes  at  100°  C. ;  after  15  miuuies 
few  survive,  after  30  minutes  none.  Falcioni  ^  studied  the  suhjcct  in 
view  of  tlie  dangers  of  the  suhcutaneous  injection  of  gelatin.  Jle  im- 
pregnated gelatin  with  spores  of  tetanus  bacilli  grown  in  agar  or  broth 
for  10  to  12  days,  and  used  Koch's  steam  sterilization.  He  found  the 
spores  to  resist  destruction  for  2i/2,  but  not  for  3,  hours  in  streaming 
steam. 

The  experimental  results  are,  therefore,  sufficiently  varied  and  con- 
flicting to  suggest  that  races  of  tetanus  bacilli  exist,  the  spores  of  which 
vary  widely  in  their  resistance  to  moist  heat  at  100°  C.  Theobald 
Smith  ^  found  that  under  certain  conditions  of  cultivation  some  tetanus 
spores  survive  a  single  boiling  or  streaming  steam  for  20  minutes  reg- 
ularly, usually  for  40  minutes,  and  occasionally  for  60  minutes;  in  one 
case  70  minutes'  exposure  did  not  destroy  the  spores.  He  also  showed 
the  possibility  of  tetanus  spores  surviving  in  culture  fluids  sterilized  by 
discontinuous  boiling  or  steaming  in  routine  laboratory  work  for  fully 
20  minutes  on  three  successive  days. 

Tetanus  spores  resist  the  action  of  5  per  cent,  carbolic  acid  for  10 
hours,  but  are  killed  in  15  hours.  A  5  per  cent,  solution  of  carbolic 
acid,  however,  to  which  0.5  per  cent,  of  hydrochloric  acid  has  been 
added,  destroys  them  in  2  hours.  Bichlorid  of  mercury,  1-1,000,  kills 
the  spores  in  3  hours,  and  in  30  minutes  when  0.5  per  cent,  of  hydro- 
chloric acid  is  added  to  the  solution.  According  to  Park,  silver  nitrate 
solution  destroys  the  spores  of  average  resistance  in  1  minute  in  1  per 
cent,  solution,  and  in  about  5  minutes  in  a  1  to  1,000  solution.  Tetanus 
spores  are  destroyed  with  certainty  when  exposed  to  dry  heat  at  or 
above  160°  C.  for  one  hour,  or  to  steam  at  120°  C.  for  20  minutes.  En- 
tire confidence  may  be  jDlaced  upon  either  of  these  two  methods. 

Direct  sunlight  does  not  kill  the  spores,  but  seems  to  diminish  their 
virulence.  Under  certain  circumstances  they  may  live  a  very  long  time ; 
Henrijean  rej^orts  that,  by  means  of  a  splinter  of  wood  Avhich  once 
caused  tetanus,  he  was  able  after  11  years  again  to  cause  the  disease 
by  inoculating  an  animal  with  the  infective  material. 

Prophylaxis. — Local  Treatment  of  Wounds. — Wounds,  however  in- 
significant, should  be  thoroughly  cleansed.  Punctured  or  lacerated 
wounds  in  which  there  is  special  danger  of  tetanus  should  be  freely 
opened,  and  every  particle  of  foreign  matter  carefully  removed.  Prompt- 
ness in  cleansing  the  wound  surgically  is  almost  as  important  as  thor- 
oughness.    Wounds  containing  garden  earth,  street  dust,  or  other  mate- 

*  Grenzgeb.  d.  Bled.  u.  Chir..  1902.  X,  p.  235. 

"  Annali  d'igiene  sperimentale,   1904,  N.  S.,  XIV,  p.   319. 

^Jour.  A.  M.  A.,  March  21,  1908,  Vol.  L,  pp.  929-934. 


TETANUS  81 

rial  liable  to  contain  tetanus  spores  should  receive  special  consideration. 
After  laying  open  and  thoroughly  cleansing  such  wounds,  it  may  be  ad- 
visable to  disinfect  them  with  the  actual  cautery  or  strong  chemical 
agents.  For  this  purpose  nitric  acid,  carbolic  acid  (from  25  per  cent,  to 
pure),  or  formalin  in  full  strength  may  be  used.  Silver  nitrate  destroys 
the  tetanus  spores  in  laboratory  experiments,  but  lacks  penetration  in 
the  presence  of  albuminous  matter.  It  is  sometimes  good  practice  to 
totally  excise  the  wound,  and  even  amputation  must  be  considered  in 
certain  cases.  The  division  of  the  umbilical  cord  and  the  treatment  of 
the  navel  in  the  newborn  must  be  done  under  the  strictest  asepsis. 
All  wounds  in  which  there  is  any  suspicion  of  tetanus  should  be  kept 
open  and  freely  drained,  and  otherwise  treated  so  as  to  discourage 
anaerobic  conditions. 

Tetanus  spores  gain  entrance  into  wounds  not  only  from  manure, 
garden  soil,  street  dust,  and  similar  sources,  but  also  from  the  hands, 
instruments,  bandages,  suture  material,  or  other  objects.  It  is  impor- 
tant to  remember  that  the  tetanus  spore  is  exceedingly  resistant  to  heat 
and  chemical  agents,  and  that  in  surgical  and  obstetrical  practice  con- 
fidence should  not  be  placed  simj^ly  upon  brief  boiling  to  destroy  the 
spores.  Very  particularly  care  must  be  exercised  in  the  disinfection 
of  substances  injected  into  the  body,  such  as  gelatin  and  other  organic 
materials.  For  the  destruction  of  tetanus  spores  complete  confidence 
may  be  placed  in  the  autoclave,  in  which  a  temperature  of  120°  C.  for 
20  minutes  is  attained,  or  exposure  to  dry  heat  at  160°  C.  for  1  hour. 

It  should  be  remembered  that  tetanus  toxin  is  manufactured  in  the 
wound  and  is  thence  transported  mainly  along  the  nerve  roots  to  the 
spinal  cord  and  brain.  It  is  therefore  important  to  destroy  or  neutral- 
ize the  toxin  in  the  wound.  For  this  purpose  dry  tetanus  antitoxin  may 
be  dusted  upon  the  wound.  Formaldehyd,  even  in  comparatively  weak 
solutions,  destroys  the  activity  of  tetanus  toxin. 

Specific  Prophylaxis. — Tetanus  antitoxin  is  a  specific  and  trustworthy 
preventive.  Its  use,  however,  must  be  understood  to  achieve  satisfactory 
results.  The  antitoxin  must  be  administered  before  the  advent  of 
symptoms,  for  after  the  tetanus  toxin  has  combined  with  the  motor 
nerve  cells  in  the  central  nervous  system  it  can  neither  be  displaced  nor 
neutralized  with  antitoxin.  In  such  cases  the  most  that  the  antitoxin 
can  do  is  to  combine  wi4:h  and  neutralize  the  free  toxin  and  thus  pre- 
vent further  damage.  This  in  itself  is  quite  worth  while  in  the  treat- 
ment of  tetanus.  At  least  1,500  units  of  tetanus  antitoxin  should  be 
given  as  a  prophylactic  dose.^     It  is  important  to  remember  that  the 

^As  soon  as  symptoms  appear  20,000  units  or  more  of  tetanus  antitoxin 
should  be  introduced  directly  into  the  circulation  by  intravenous  injection;  some 
antitoxin  may  also  be  injected  into  the  nerves  leading  from  the  wound.  Nicoll 
has  obtained  favorable  results  with  antitoxin,  even  after  symptoms  have  devel- 
oped, by   injecting   3   to  5,000  units  into  the  spinal   canal,    10,000  units   intra- 


82  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

tetanus  antitoxin  is  eliminated  or  otherwise  disposed  of  in  the  hody 
jn  the  eonrse  of  10  days  or  2  weeks.  Therefore,  in  eases  in  which  fh(! 
wound  does  not  heal  well,  as  a  result  of  mixed  infection,  or  for  otix  r 
reasons,  it  is  desirable  to  repeat  the  injection.  This  may  be  done  at 
intervals  as  long  as  the  danger  persists.  Occasionally  tetanus  bacilli 
persist  in  the  pus-infected  tissues,  and,  when  the  injected  antitoxin  has 
been  exhausted,  there  may  occur  a  late  development  of  tetanus,  liowan  ^ 
reports  a  fatal  case  of  tetanus  in  spite  of  the  prophylactic  use  of  2,000 
units  of  antitetanic  serum,  given  5  hours  after  the  accident.  In  this 
case,  however,  the  symptoms  appeared  25  days  later.  The  wound  in 
this  case  was  a  compound  fracture  with  a  free  discharge  of  rather 
foul-smelling  pus.  Instances  in  which  1,500  units  of  tetanus  antitoxin 
have  failed  to  prevent  the  development  of  tetanus  in  this  country  are 
rare.  The  few  failures  in  France  and  Germany  may  be  attributed  to  the 
fact  that  in  those  countries  it  is  customary  to  use  a  smaller  amount  or 
a  less  potent  serum  than  is  used  in  this  country. 

Wounds  produced  by  blank  cartridges  and  other  Fourth  of  July 
accidents  should  always  be  regarded  as  suspicious,  and  should  be  given 
careful  local  treatment,  supplemented  with  a  prophylactic  injection  of 
antitoxin.  The  prevention  of  tetanus  complication  of  vaccine  wounds 
consists  in : 

1.  The  use  of  a  reliable  vaccine  which  has  been  biologically  tested 
in  accordance  with  the  federal  act. 

2.  Proper  methods  of  vaccination  to  avoid  unnecessary  scabs  and 
anaerobic  wound  conditions. 

3.  Surgical  asepsis  of  the  operation  and  after-treatment. 

Tetanus  and  other  wound  infections  may  be  avoided,  in  those  ex- 
posed to  accidents,  by  cleanliness  of  body  and  clothing.  A  bath  before 
a  battle  is  a  reasonable  protection  said  to  be  adopted  in  the  Japanese 
Army  and  Navy.  The  common  experience  of  mankind  teaches  that 
most  wounds  heal  without  tetanus,  and  that  tetanus  is,  in  fact,  a  rela- 
tively rare  infection.  The  physician,  however,  is  in  no  case  justified 
in  taking  chances,  and  it  is  one  of  the  duties  of  the  medical  profes- 
sion to  teach  the  public  that  it  pays  to  thoroughly  cleanse  and  care 
for  wounds,  however  trivial,  at  once,  and  in  accordance  with  modern 
methods. 

venously,  and  10,000  units  subcutaneously.     (Jour.  A.  M.  A.,  LXIV,  24,  June  12, 
1915,  p.  1982.)      In  tetanus,  as  in  diphtheria,  time  is  the  important  element.     A 
few  units  introduced  early  are  wortli  more  than  thousands  late. 
Vow.  A.  M.  A.,  XIV,  No.  7,  Feb.   12,  1910,  p.  533. 


CHAPTER   II 

DISEASES  SPREAD  LARGELY  THROUGH  THE  ALVINE 
DISCHARGES 


TYPHOID  FEVER 

Typhoid  fever  is  a  sanitary  problem  of  first  magnitude,  especially 
in  this  country,  where  it  is  unduly  prevalent.  In  the  United  States 
typhoid  fever  stands  fourth  on  the  list  of  mortality  tables:  tuberculosis 
comes  first,  then  pneumonia,  cancer,  and  typhoid  fever.  The  aver- 
age fatality  from  typhoid  fever  being  nearly  10  per  cent.,  it  would, 
therefore,  take  still  higher  rank  on  the  morbidity  tables.  In  1910 
there  were  25,000  deaths  from  typhoid  fever  in  the  United  States, 
representing  at  least  250,000  cases — one  jjerson  in  every  400. 

Our  general  attitude  toward  typhoid  fever  is  inconsistent;  familiar- 
ity has  bred  a  remarkable  indifference  to  the  disease.  Every  case  of 
typhoid  fever  means  a  short  circuit  between  the  alvine  discharges  of 
one  person  and  the  mouth  of  another.  The  physician  has  a  dual  duty 
in  the  care  of  a  case  of  typhoid  fever:  one  is  to  assist  the  patient, 
the  other  is  to  protect  the  community.  On  the  other  hand,  the  people 
should  learn  the  lesson  that  a  case  of  typhoid  fever  should  be  regarded 
as  seriously  as  a  case  of  cholera.  These  two  diseases  present  many 
features  in  common.  Both  are  intestinal  infections  of  bacterial  na- 
ture; in  both  diseases  the  alvine  discharges  contain  the  microorgan- 
isms which  reinfect  another  person  when  taken  by  the  mouth.  Both 
diseases  prevail  especially  in  hot  weather,  both  diseases  are  peculiar 
to  man,  so  that  the  patient  is  the  fountainhead  of  each  infection. 
Water,  food,  fingers,  and  flies  play  a  similar  role  in  both  instances. 
In  the  case  of  cholera  the  dread  of  the  disease  is  an  important  factor 
in  keeping  it  out  of  the  country  or  in  preventing  its  spread  when  once 
introduced.  By  strange,  contrast,  there  is  a  remarkable  indifference 
to  typhoid  fever.  A  wholesome  fear  of  typhoid  fever  would  materially 
assist  the  health  authorities  in  combating  what  may  be  considered 
one  of  the  major  sanitary  problems  of  the  age.  From  the  standpoint 
of  preventive  medicine,  it  is  proper  to  regard  an  outbreak  of  typhoid 
fever  as  a  reproach  to  the  sanitation  and  civilization  of  the  community 
in  which  it  was  contracted.  When  the  matter  is  better  understood  health 
authorities  will  be  held  responsible  for  this  and  other  preventable  infec- 

83 


84  DISEASES  HAVING  SPECIAL  PEOPHYLAXIS 

tioiis,  just  as  soiiK'  one  is  now  held  responsible  for  preventable  accidents.^ 

Much  liarin  has  been  done  by  insistin<^  that  typhoid  fever  is  in- 
fectious, but  not  contagious;  it  is  both — that  is,  communicable.^ 

Typhoid  fever  occurs  both  in  endemic  and  epidemic  forms.  It 
may  truly  be  regarded  as  pandemic.  Normally,  typhoid  fever  is  a 
warm  weather  disease.  It  recurs  as  an  annual  crop  from  July  to  Octo- 
ber.^ Epidemics  caused  by  infected  water  occur  especially  in  the 
early  spring,  late  fall,  or  winter  months.  Milk  outbreaks  may  occur 
at  any  time  of  the  year.  Autumnal  typhoid  in  our  cities  is  due  partly 
to  infection  contracted  at  health  resorts,  and  has,  therefore,  been  called 
a  vacation  disease. 

Typhoid  fever  is  more  prevalent  in  rural  districts  than  in  cities. 
In  the  United  States  there  is  more  typhoid  fever  in  the  southern 
states  than  in  the  northern  zone.  The  only  explanation  to  account 
for  this  is  the  influence  of  temperature,  rural  conditions,  and  asso- 
ciation with  the  negro.  Typhoid  fever  is  no  respecter  of  rich  or  poor; 
it  attacks  those  in  robust  health,  all  ages,  both  sexes. 

Typhoid  fever  is  a  disease  which  ordinarily  attacks  the  individual 
during  the  period  of  greatest  economic  value  to  the  community.  The 
economic  loss,  therefore,  is  appalling,  and  has  been  estimated  to  reach 
the  sum  of  no  less  than  $100,000,000  annually  in  the  United  States. 
Again,  typhoid  fever  is  an  infection  against  which  the  individual  alone 
cannot  protect  himself  wholly  without  the  aid  of  the  community. 

Prevalence. — Typhoid  fever  prevails  more  or  less  in  all  countries — 

the  amount  of  the  disease,  however,  varies  greatly.     It  appears  to  be 

a  disease  of  defective  civilization,  for  those  communities  paying  least 

attention  to  sanitation,  as  a  rule,  suffer  most.     In  the  United  States 

there  are  comparatively  few  communities  of  1,000  inhabitants  or  more 

which,  during  any  period  of  twelve  consecutive  months  within  the  last 

decade,  have  been  entirely  free  from  typhoid  fever.     According  to  the 

United  States  census  report  for  1900,  the  average  typhoid  death-rate 

in  the  United  States  was  46.5  per  100,000  inhabitants.     In  1908  the 

death  toll  from  typhoid  fever  was  no  less  than  35,000  in  the  United 

States.     In  other  words,  one  person  in  about  200  in  the  United  States 

contracted  typhoid  fever  that  year.     It  is  estimated  that  in  1910-11  the 

number  of   deaths  was  reduced  to  about  25,000.     The   seriousness  of 

these  figures   may   be  judged  by  estimating  the   probable   number   of 

cases  of  typhoid  fever  among  persons  handling  the  milk  supply.     Take, 

for  instance,  a  city,  as  Washington,  receiving  its  milk  from  a  thousand 

dairy   farms.      On   the    average   there   will   be   about   four   persons   on 

each  farm  who  in  one  way  or  another  come  in  contact  with  the  milk. 

That  makes   4,000   persons   among   whom   about   20    cases   of   typhoid 

^  See  Vennen  vs.  New  Dells  Lumbar  Co.,  page   1046. 

^  For  distinction  between  these  terms  see  page  .366. 

^In  tlie  southern  hemisphere  tlie  typhoid   season   is   during  our  winter. 


TYPHOID    FEVER 


85 


may  be  expected  to  occur  annually.  Add  to  this  the  carriers  and  it  is 
no  wonder  that  milk-borne  outbreaks  of  tyjjhoid  fever  are  common  occur- 
rences. 

The  rate  of  prevalence  of  typhoid  fever  in  the  United  States  in 
comparison  with  the  rates  of  many  other  countries  is  very  high.  Thus, 
the  annual  death-rate  from  typhoid  fever  per  100,000  population  for  the 
period  1901-1905  was:  in  Scotland,  6.2;  in  Germany,  7.6;  in  England 
and  Wales,  11.2;  in  Belgium,  16.8;  in  Austria  (1901-1904),  19.9;  in 
Hungary,  28.3 ;  in  Italy,  35.2  ;  while  the  rate  in  the  United  States  during 
the  same  period  was  about  4:6.5.  A  great  improvement  in  the  typhoid 
situation  is  now  taking  place  in  this  country — and  many  states  and  cities 
are  reporting  figures  approaching  the  European  rates. 

A  comparison  between  the  prevalence  of  typhoid  fever  in  this 
country  and  abroad  is  impressive.  The  following  ten  European  cities 
with  a  total  population  of  about  15,000,000  have  an  average  typhoid 
rate  of  2.4  per  100,000  during  the  10  years  1901-10 1^ 

ANNUAL    DEATH-RATES   FROM   TYPHOID   FEVER  PER   100,000  POPULATION   IN   10 

EUROPEAN  CITIES 


Average 

Average 

.  for  10 
years, 

for  5 
years, 

1906 

1907 

1908 

1909 

1901-lClO 

1901-1905 

1.7 

3 

2 

2 

1 

5 

2.4 

3 

4 

2 

2 

1.7 

2.5 

4 

2 

3 

3 

1.9 

2.9 

8 

3 

3 

2 

1.2 

3.7 

4 

5 

3 

4 

2.8 

3.7 

4 

4 

3 

4 

3.3 

3.8 

4 

4 

4 

4 

4.2 

4.2 

4 

7 

2 

6 

4.2 

4.5 

8 

4 

2 

7 

2.7 

4.7 

8 

6 

4 

5 

2.2 

Stockholm . 
Christiania . 
Munich .... 
Edinburgh  . 
Vienna  .... 
Hamburg .  . 

BerUn 

Dresden .  .  . 
Copenhagen 
London .... 


1.8 
1.6 
1.4 
.3 
3.8 
4.1 
2.9 
2.2 
3.6 
3.3 


The  following  fifteen  European  cities  with  a  population  of  about 
9,000,000  had  a  typhoid  death-rate  of  5.3  per  100,000  in  1909  and 
only  4.5  in  1910 : 

^  These  facts  and  tlie  following  instructive  tables  are  taken  from :  "The 
Necessity  of  a  Safe  Water  Supply  in  the  Control  of  Typhoid  Fever,"  by  Allan 
J.  McLaughlin,  U.  8.  Pub.  Health  Reports,  XXVII,  12,  March  22,  1912. 


8G        DISEASES   SPREAD   TIIKOUCH   Al.VIXE   DISCHARGES 

ANNUAL  DEATH-RATES  FROM  TYPHOID  FEVER  PER  lOO.fKX}  POPUI  A'l'IOX  IN  lOOTJIER 

EUROPEAN  CITIES 


Citv 


Frankfort 

Antwerp 

Bristol 

Nuremberg 

Birmingham 

Belfast 

Lyon 

Leeds 

Lii'erpool 

Sheffield 

Rotterdam 

Amsterdam 

Paris 

Bradford 

Leipzig 

Total  average  rate 


l.o 

0.0 

1.0 

2.3 

2.8 

2.1 

2.6 

5.1) 

3.9 

5.2 

3.9 

5.8 

4.4 

7.2 

3.8 

8.4 

3.9 

9.4 

3.0 

6.4 

6.5 

3.8 

6.7 

8.4 

5.6 

4.3 

9.2 

8.3 

7.5 

4.5 


The  following  eight  European  cities  with  a  total  i^opulation  of 
7,500,000  had  a  typhoid  death-rate  of  13.9  in  1909  and  15.6  in  1910. 
These  rates  would  have  been  considered  low  in  America  before  1910, 
but  the  European  officials  consider  the  persistence  of  such  rates  to  be  a 
reflection : 


ANNUAL  DEATH-RATES  FROM  TYPHOID  FEVER  PER  100,000  POPULATION  IN  8  OTHER 

EUROPEAN  CITIES 


City 


1909 


1910 


Glasgow 

Budapest 

Brussels 

Dublin 

Manchester 

Moscow 

Warsaw 

Petrograd 

Total  average 


12.5 

6.4 

9.4 

13.6 

7.4 

16.1 

15.7 

12.2 

13.9 

10.3 

13.8 

15.0 

13.5 

17.4 

25.2 

33.7 

To  recapitulate,  in  northern  Europe  the  33  principal  cities,  with 
an  aggregate  population  of  31,500,000,  had  an  average  typhoid  death- 
rate  per  100,000  population  of  6.5  in  1909  and  1910.  This  includes 
such  a   notorious  typhoid   center  as   Petrograd,   which  had   a   rate   of 


TYPHOID    FEVER 


87 


33.7  in  1910.     The  high  rate  in  Petrograd  is  considered  to  be  due  to 

the  water  supply,  which  is  partly  filtered  and  partly  raw  Neva  water. 

Let  us  now  compare  these  rates  with  typhoid  fever  in  America : 


Annual  Death  Rates  from  Typhoid  Fever  per  100,000  Population  in  50  Cities 
OP  the  United  States  Having  More  than  100,000  Inhabitants 


City 

1909 

1910 

1911 

1912 

1913 

1914 

1915 

Birmingham,  Ala 

59.7 
16.1 
11.2 
13.9 
24.1 

9.0 
20.5 
34.3 
50.6 
12.6 
22.0 
45.3 
28.4 
24.9 
13.8 

7.7 
21.3 
10.5 

8.4 
20.5 
17.2 
21.0 
18.9 
29.3 
16.2 
36.8 

8.8 
11.9 

9.7 
19.0 
23.8 
12.1 

9.4 
11.2 
13.3 
13.3 
19.6 
26.9 
41.7 
22.0 
22.3 
24.6 
16.4 
11.4 
48.8 
52.0 
24.1 
23.8 
43.2 
21.4 

49.5 
14.2 
16.5 
15.5 
27.5 

4.9 
17.9 
23.2 
50.1 
13.7 
28.5 
31.7 
31.5 
42.0 
11.3 

9.5 
15.0 
19.7 
15.7 
23.0 
28.3 
58.7 
19.5 
54.4 
14.9 
86.7 
11.5 
13.1 

7.1 
14.0 
20.4 
11.6 
13.7 
28.2 

8.8 
17.9 
18.1 
21.4 
37.2 
22.4 
17.5 
27.8 
16.9 
17.9 
27.4 
48.9 
21.9 
14.2 
45.4 
45.7 

45.5 
11.6 
14.0 
15.3 
18.0 

3.8 
24.9 
22.2 
66.1 
10.9 
25.8 
23.7 
31.0 
27.6 

8.7 

2.8 
14.7 

7.3 

6.0 
15.8 
26.7 
11.9 
10.5 
29.9 
16.1 
18.1 

7.2 
10.5 

7.0 
18.8 
25.0 
10.9 
10.6 
16.2 
11.4 
14.2 
13.9 
18.6 
23.1 
19.1 
14.6 
25.6 
14.3 
12.1 
65.4 
53.9 
17.8 
10.3 
35.6 
19.0 

37.3 
15.0 
13.7 
13.6 

15.2 

8.3 

24.4 

23.0 

41.9 

7.4 

17.8 

21.8 

14.0 

24.6 

8.0 

3.7 

18.0 

10.1 

3.3 

17.5 

33.9 

11.7 

10.6 

12.0 

10.7 

14.0 

7.8 

8.1 

5.4 

17.7 

11.8 

9.6 

11.7 

16.7 

7.7 

6.9 

19.6 

19.1 

31.7 

16.6 

12.8 

13.1 

10.3 

10.2 

58.9 

32.8 

16.7 

7.6 

17.4 

25.7 

36.0 
12.1 
12.0 
16.1 
13.5 

6.2 
12.7 
16.4 
21.9 
10.4 
24.4 
23.2 
16.9 
23.8 

8.2 

9.2 

8.9 
10.0 

5.8 
29.4 
18.2 
12.0 

9.1 
21.9 
16.9 

7.6 
10.8 

8.7 

8.3 
27.4 
15.4 

7.0 

8.9 
13.0 

6.8 
14.1 
19.1 
18.0 
41.6 

6.5 
15.7 
19.5 

9.4 
11.2 
34.2 
36.9 
20.3 

4.7 

7.0 
11.3 

39.7 

7.7 

6.6 

12.7 

9.0 

3.5 

15.2 

11.9 

46.3 

6.6 

25.8 

25.9 

21.9 

22.6 

9.0 

1.8 

9.6 

10.8 

3.8 

14.1 

27.6 

12.5 

11.0 

16.3 

12.0 

4.5 

7.5 

7.5 

4.5 

17.5 

16.3 

6.3 

10.2 

10.0 

6.2 

8.1 

13.2 

11.3 

36.9 

6.9 

7.6 

15.0 

9.2 

11.0 

42.6 

51.3 

14.8 

7.0 

12.5 

8.1 

33.7 

Los  Angeles,  Cal 

5  5 

Oakland,  Cal 

6.7 

San  Francisco,  Cal 

Denver,  Colo 

9  4 
6.6 

Bridgeport,  Conn 

New  Haven,  Conn 

Washington,  D.  C 

Atlanta,  Ga 

5.1 
18.3 
11.7 
11.1 

Chicago  111 

5.4 

Indianapolis,  Ind 

Louisville,  Ky 

12.3 
12.0 

New  Orleans,  La 

21.5 

Baltimore,  Md 

21.9 

Boston,  Mass 

5.5 

Cambridge,  Mass 

Fall  River,  Mass 

1.8 
11.8 

Lowell,  Mass 

16.0 

Worcester,  Mass 

5.6 

Detroit,  Mich 

12.8 

Grand  Rapids,  Mich 

Minneapolis,  Minn 

St.  Paul,  Minn 

24.6 
7.1 

7.4 

Kansas  City,  Mo 

St.  Louis,  Mo 

7.2 
7.0 

Omaha,  Nebr 

3.7 

Jersey  City,  N.  J 

Newark,  N.  J 

5.6 
2.5 

Paterson,  N.  J 

5.1 

Albany,  N.  Y       

12.6 

Buffalo,  N.  Y 

9.9 

New  York,  N.  Y 

Rochester,  N.  Y 

6.0 
6  0 

Syracuse,  N.  Y 

5.9 

Cincinnati,  Ohio 

Cleveland,  Ohio 

7.8 
7.8 

Columbus,  Ohio 

13.3 

Dayton,  Ohio 

13.6 

Toledo,  Ohio 

23.9 

Portland,  Oregon 

Philadelphia,  Penn 

Pittsburgh,  Penn 

Scranton,  Penn    

5.2 

6.6 

24.7 

10.4 

Providence,  R.I 

Memphis,  Tenn 

8.4 
24.6 

Nashville,  Tenn 

35.1 

Richmond,  Va 

12.7 

Seattle,  Wash     

2.5 

Spokane,  Wash 

10.7 

Milwaukee,  Wis 

4.5 

OfBcial  figures  kindly  furnished  by  Richard  C.  Lappin,  Chief  Statistician  Division  of  Vital  Statis- 
tics, Bureau  of  the  Census,  U.  S.  Dept.  of  Commerce.  Data  for  191o  from  J.  A.  M.  A.  April  22,  1916, 
p.  1305. 


88        DTSEASl^LS   SPRKAD   ^rJlUOUGlI   ALVIXE   DiSOHAKGES 

These  50  registration  cities  in  the  United  States  have  an  aggregate 
population  of  over  20,000,000.  The  average  typhoid  death-rate  in 
these  cities  for  1910  was  25  per  100,000  irdiabitants. 


Unit  of  comparison 

Aggregate 
population 

Deaths  per 
100,000  from 

typhoid 
fever,  1910 

33  principal  European  cities  in  Russia,  Sweden,  Norway,  Austria- 
Hungary,    Germany,    Denmark,    France,    Belgium,    Holland, 

31,500,000 
20,250,000 

6.5 

25.0 

18.5 

The  excess  of  18  deaths  per  100,000  in  the  nrban  population  alone 
shows  that  we  have  had,  in  the  50  cities  mentioned  above,  at  least  3,600 
deaths,  and  probably  36,000  cases  of  typhoid  fever,  which  were  pre- 
ventable and  should  never  have  occurred.  For  the  whole  United  States 
the  number  of  cases  for  each  year  readily  preventable  by  methods  within 
our  grasp  would  probably  reach  175.000,  and  the  deaths  so  avoided  would 
total  about  16,000.  In  1909  there  were  more  cases  of  typhoid  fever 
in  the  United  States  than  there  were  cases  of  plague  in  India,  in  spite 
of  the  fact  that  India's  population  is  two  and  one-half  times  that  of  the 
United  States. 

The  typhoid  rates  in  our  larger  cities  are  coming  down,  owing  to  im- 
proved water  supplies  and  better  sanitary  conditions.  In  1912,  more 
than  half  the  cities  in  this  country  with  over  100,000  population  had 
typhoid  rates  under  13.9.  In  fact  the  improvement  in  our  typhoid  situ- 
ation is  one  of  the  great  sanitary  reforms  now  going  on. 

Residual  or  "Normal"  Typhoid. — When  a  city  such  as  Albany, 
Chicago,  Lawrence,  Lowell,  or  Pittsburgh,  which  has  been  using  grossly 
polluted  water,  is  furnished  with  a  water  supply  of  good  sanitary 
quality,  there  at  once  results  a  marked  reduction  in  the  amount  of 
typhoid  fever.  The  curve  is  not  only  lowered,  but  it  is  also  changed 
in  character.  The  remaining  typhoid  after  the  water-borne  infec- 
tion has  been  removed  is  known  as  residual  typhoid,  and  the  curve 
in  such  cases  is  spoken  of  as  the  "normal"  typhoid  curve.  The 
normal  curve  shows  a  distinct  summer  prevalence  recurring  with 
marked  regularity  each  year,  and  lacks  the  great  irregularities  which 
characterize  the  curve  of  a  community  drinking  badly  infected  water. 
Normal  typhoid  is  endemic  typhoid;  Sedgwick  has  proposed  the  name 
"prosodemic"  {proso,  through,  and  demos,  the  people)  as  more  expres- 
sive of  this  type  of  the  disease.    The  amount  of  residual  typhoid  varies 


TYPHOID    FEVEE  89 

markedly  in  different  localities;  thus  it  is  twice  as  high  in  the  southern 
as  in  the  northern  part  of  our  country ;  it  is  much  greater  here  than  in 
most  parts  of  Europe. 

Channels  of  Entrance  and  Exit. — The  typhoid  bacillus  probably  al- 
ways enters  by  the  mouth.  Typhoid  fever  is  generally  regarded  as 
primarily  a  gastro-intestinal  infection,  although  the  disease  itself  is 
not  produced  unless  the  blood,  glands,  and  other  structures  of  the 
body  are  invaded  with  the  specific  microorganism.  The  typhoid  bacil- 
lus grows  and  multiplies  in  the  intestinal  tract,  penetrates  the  mu- 
cosa, and  thus  invades  the  body.  The  bacillus  leaves  the  body  mainly 
in  the  feces  and  urine,  occasionally  in  the  sputum  and  other  discharges. 
Typhoid  bacilli  appear  in  the  feces  early  in  the  disease;  sometimes  be- 
fore the  fever.  Later  in  the  disease  they  diminish  in  niimber  and 
usually  disappear  during  convalescence,  although  they  may  continue  in- 
definitely (see  "Bacillus  Carriers,"  page  92).  The  feces  may  contain 
only  a  few  typhoid  bacilli;  usually  they  are  present  in  considerable 
numbers;  occasionally  they  occur  almost  in  pure  culture,  practically 
replacing  the  colon  bacillus. 

Typhoid  bacilli  commonly  appear  in  the  urine  about  the  second, 
third,  or  fourth  week.  They  grow  well  in  this  fluid  both  within  and 
without  the  body,  and  may  be  present  in  such  enormous  numbers  that 
the  urine  resembles  a  24-hour-old  bouillon  culture.  From  the  stand- 
point of  prevention,  it  is  very  important  not  to  neglect  the  virus  in 
the  urine.  Urotropin  (hexamethylenamin)  in  ten-grain  doses  or  more 
three  times  a  day  diminishes  the  frequency  of  typhoid  bacilluria,  and  is 
also  effective  in  curing  this  condition  when  once  established. 

The  sputum  ordinarily  does  not  contain  the  bacilli  unless  there  is 
a  pneumonia  or  severe  bronchitis.  Gould  and  Quales,  and  also  Purjesz 
and  Perl,^  have  recently  found  typhoid  bacilli  in  about  50  per  cent,  of 
the  cases  by  rubbing  the  gums,  tonsils,  and  tongue  of  patients  suffer- 
ing with  typhoid  fever.  These  microorganisms  from  the  mouth  were 
found  as  late  as  the  fourth  to  eighth  week  of  convalescence.  These 
findings  are  important  both  from  the  standpoint  of  diagnosis  and 
epidemiology.  The  bacilli  may  be  eliminated  with  the  discharges  from 
abscesses,  such  as  periostitis,  months  and  even  years  after  the  disease. 

Diagnosis. — An  early  diagnosis  of  typhoid  fever  is  important  not 
only  for  the  successful  treatment  of  the  patient,  but  is  of  vital  impor- 
tance in  controlling  the  spread  of  the  infection.  The  early  diagnosis 
can  only  be  assured  through  laboratory  methods.  Typhoid  bacilli  may 
be  isolated  either  from  the  blood  or  the  feces. 

Blood  Cultures. — Probably  the  easiest  method,  as  well  as  the  one 
giving  the  maximum  information,  is  through  blood  ciiltures.  The  tak- 
ing of  a  little  blood  for  this  purpose  is  no  more  difficult  or  annoying 

"■Wien.  klin.  Woch.,  1912,  XXV,  1494. 


90        DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

to  ilio  ]);ili('nt  tluui  ,swal)l)ij),i(  ilu;  tlir(jai  for  (li|)htheria.  A  few  drops 
of  blood  may  he,  ohlaiiu'd  by  pujicturiiig  Ibc  lobe  of  the  ear  or  the 
finger,  with  the  usual  preeautions  to  prevent  bacteiial  contamination, 
A  much  better  method,  however,  consists  in  withdrawing  5  to  10  c.  c. 
of  blood  by  means  of  a  syringe  from  one  of  the  veins  at  the  bend  of 
the  elbow.  The  technic  is  very  simple,  and,  if  the  needle  is  sharp, 
the  patient  scarcely  feels  the  puncture.  In  fact,  if  the  attention  of 
the  patient  is  distracted  a  skillful  oj)erator  can  withdraw  10  c.  c.  of 
blood  in  this  way  before  the  patient  is  aware  that  anything  has  been 
done.  The  blood  may  be  planted  in  bouillon,  or,  better,  in  bile.  After 
24  hours  in  the  incubator,  any  growth  that  occurs  is  transplanted  to 
other  media,  a  pure  culture  obtained,  and  tested,  for  agglutination. 
Often  a  pure  culture  is  obtained  in  the  first  medium,  so  that  the  diag- 
nosis may  be  established  in  34  hours — at  most,  2  or  3  days. 

Typhoid  bacilli  appear  in  the  blood  early  in  the  disease,  perhaps 
occasionally  during  the  prodromal  symptoms.  Kayser  obtained  posi- 
tive results  from  90  per  cent,  in  the  first  week,  C5  per  cent,  in  the 
second,  42  per  cent,  in  the  third,  35  per  cent,  in  the  fourth.  Our 
results  in  Washington  were  approximately  the  same.  The  typhoid, 
bacilli  probably  do  not  grow  in  the  blood  during  life.  Their  presence 
in  the  blood  stream  represents  an  overflow  from  the  spleen  and  lym- 
phatic tissues.  The  presence  of  typhoid  bacilli  in  the  blood  may  be 
taken  to  mean  typhoid  fever.  The  same  cannot  always  be  said  if 
found  in  the  feces  or  urine. 

The  Feces. — From  the  feces  or  urine  typhoid  bacilli  are  best 
isolated  upon  Endo's  medium.  This  consists  of  a  4  per  cent,  alkaline 
agar  containing  fuchsin,  wdiich  has  been  decolorized  with  sodium  sul- 
phite. Upon  the  surface  of  this  medium  typhoid  colonies  appear  in 
24  hours  as  translucent,  dewdrop-like  colonies,  wdiereas  colon  bacilli 
and  other  organisms  that  produce  acid  and  split  the  fuchsin  appear 
as  red  colonies.  Suspicious  colonies  are  fished  and  may  be  tested  at 
once  under  the  microscope  for  agglutination,  or  may  be  planted  in 
bouillon  to  obtain  a  growth  sufficient  for  macroscopic  agglutination 
tests.  In  any  critical  case  pure  cultures  should  be  obtained  and  studied 
for  morphological,  cultural,  and  other  biological  characters.  A  modi- 
fied Endo's  medium  and  a  rapid  technic  for  diagnostic  purposes,  de- 
scribed by  Kendall  and  used  with  success  in  my  laboratory,  are  sum- 
marized as  follows: 

Technic. — Make  plain,  nutrient,  sugar-free  agar  as  follows :  Tap 
water  (cold),  one  thousand  cubic  centimeters;  powdered  agar,  fifteen 
grams;  peptone  (Witte),  ten  grams;  meat  extract  (Liebig),  three 
grams.  Cook  in  double  boiler  one  hour.  Make  the  reaction  just  al- 
kaline to  litmus  by  the  cautious  addition  of  NaOH.  Cook  fifteen 
minutes  to  set  the  reaction,  and  then  filter  through  absorbent  cotton. 


TYPHOID    FEVEE  91 

The  tap  water  should  be  as  cold  as  possible  and  the  agar  should  be 
"dusted"  on  the  surface  and  allowed  to  settle  into  the  medium  before 
heat  is  applied  and  before  the  other  ingredients  are  added. 

After  filtration,  the  medium  is  stored  in  flasks  containing  known 
amounts,  conveniently  in  one  hundred-cubie-centi meter  lots,  and  steril- 
ized in  the  autoclave. 

To  use  the  medium:  (a)  Prepare  a  ten  per  cent,  solution  of  fuch- 
sin  in  ninety-six  per  cent,  alcohol,  (b)  Prepare  a  ten  jier  cent,  solu- 
tion of  sodium  sulphite  in  water. 

Add  one  cubic  centimeter  of  (a)  to  ten  cubic  centimeters  of  (b) 
and  heat  in  the  Arnold  sterilizer  for  twenty  minutes  =  (c). 

Add  one  per  cent,  of  lactose  (which  must  be  chemically  pure)  to 
the  agar  medium  described  above,  and  heat  in  the  Arnold  sterilizer 
until  the  medium  is  melted  and  the  lactose  thoroughly  distributed  in 
it.  The  decolorized  fuchsin  solution  (c)  is  then  added  in  the  pro- 
portion of  one  cubic  centimeter  of  the  mixture  to  each  one  hundred 
cubic  centimeters  of  medium;  then  thoroughly  mixed. 

Plates  are  then  poured  and  allowed  to  harden  (with  the  covers 
removed)  in  the  incubator  for  thirty  minutes,  after  which  time  they 
are  ready  for  inoculation. 

Preparation  of  Feces  for  Inoculation. — The  feces  are  collected  pref- 
erably in  the  small  rectal  tubes  described  by  Kendall.^  A  small  por- 
tion of  feces  (about  a  loopful)  is  thoroughly  emulsified  in  ten  cubic 
centimeters  of  sugar-free  broth,  and  preferably  incubated  one  hour  at 
37°  C  prior  to  the  inoculation  of  the  plates.  This  preliminary  in- 
cubation does  two  things :  the  clumps  of  bacteria  settle  down,  leaving 
a  more  uniform  suspension  of  bacteria  in  the  supernatant  fluid  for 
inoculation,  and  the  bacteria  undergo  a  slight  development  in  a  medium 
particularly  suited  for  their  growth.  The  thin  suspension  of  the  stool 
is  now  rubbed  upon  the  surface  of  the  agar  plates  by  means  of  a  bent, 
sterile,  glass  rod,  and  the  plates  incubated  for  18  hours  at  37°  C.  The 
suspicious  translucent,  colorless  colonies  are  removed  entire  to  small 
test-tubes  containing  one  cubic  centimeter  of  broth  and  incubated  for 
two  hours  at  37°  C.  At  the  end  of  this  time  there  will  be  sufficient 
growth  to  make  the  customary  microscopic  agglutination  tests.  Con- 
firmatory cultural  characters  may  be  obtained  by  inoculating  suitable 
media  from  the  same  tubes  as  those  from  which  the  organisms  for 
agglutination  were  obtained. 

Physicians  should  encourage  boards  of  health  to  furnish  diagnostic 
aids  of  a  laboratory  nature.  Such  work  should  be  in  the  hands  of 
specialists  rather  than  entrusted  to  those  who  make  occasional  anal- 
yses.    Early  and  accurate  diagnosis  is  just  as  important  to  prevent  the 

"■Boston  Med.  and  ^urg.  Jour.,  CLXIV,  No.  1,  Sept.,  1911. 


92        DISEASES   SPlfEAD   TlIIfOUrilL   ALVIXE    JMSCIIARCES 

spread,  of  other  coinmuiiieable  diseases  as  it  is  with  typhoid.  These 
facts  emphasized  here  will  not  be  repeated  under  each  disease. 

Bacillus  Carriers. — About  2  to  4  per  cent,  of  all  cases  of  typhoid 
fever  the  patient  continues  to  shed  typhoid  bacilli  in  tlie  urine  or 
feces  during  and  after  convalescence.  Some  persons  shed  typhoid  bacilli 
without  a  clinical  history  of  having  had  the  disease.  We  therefore 
recognize  three  kinds  of  carriers :  acute,  chronic,  and.  temporary.  An 
acute  typhoid  bacillus  carrier  continues  to  discharge  the  infection  not 
longer  than  6  weeks  following  convalescence.  A  chronic  carrier  con- 
tinues to  discharge  the  bacilli  6  weeks  longer.  A  temporary  carrier 
is  a  person  who  has  not  had  clinical  typhoid  fever  but  who  discharges 
typhoid  bacilli  for  a  short  period.  Albert  states  that  25  per  cent,  of  all 
chronic  typhoid  carriers  have  never  had  typhoid  fever;  and  further 
estimates  that  one  in  every  1,000  of  the  general  population  is  a  carrier. 

While  it  would  seem  that  typhoid  bacilluria  should  be  especially 
dangerous,  a  study  of  the  cases  indicates  that  most  of  the  outbreaks 
that  have  been  traced  have  been  due  to  carriers  who  discharge  the 
organisms  in  their  feces  rather  than  in  the  urine.  It  seems  that  some 
typhoid  carriers  are  more  dangerous  than  others.  More  cases  are 
traced  to  women  ^  than  to  men.  This  is  probably  owing  to  the  fact 
that  the  chief  danger  lies  in  handling  foodstuffs,  so  that  a  carrier  occu- 
pied as  a  cook  or  waitress,  or  on  a  dairy,  is  a  special  menace. 

Sawyer  ^  reports  a  very  instructive  history  of  a  typhoid  carrier 
(H.  0.)  responsible  for  several  outbreaks.  The  carrier  was  carefully 
studied  over  a  period  of  several  years,  during  which  time  he  infected 
thirty  persons,  five  of  whom  died.  Frequent  examinations  of  feces  of 
this  carrier  gave  negative  results  for  four  months  after  he  had  been 
treated  with  autogenous  typhoid  vaccines ;  nevertheless,  he  infected  three 
persons  when  subsequently  released  from  quarantine  on  parole.  The 
removal  of  the  gall-bladder  failed  to  cure  H.  0.,  for  typhoid  bacilli 
were  found  in  the  feces  several  times  after  the  operation.  It  is  particu- 
larly noteworthy  that  41  successive  examinations  of  feces  during  a 
period  of  fourteen  months  all  proved  negative,  yet  the  typhoid  bacillus 
was  finally  isolated  from  the  stomach  contents  containing  bile.  This 
carrier,  on  account  of  the  virulence  of  the  organism,  or  careless  per- 
sonal habits,  is  unusually  dangerous  and  represents  a  class  that  should 
be  controlled  by  quarantine  or  close  supervision.  . 

Another  instructive  outbreak  caused  by  a  carrier  is  reported  by 
Sawyer  ^  in  which  93  cases  of  typhoid  fever  occurred  in  Hanford,  Cal., 
as  a  result  of  infected  food  served  at  a  public  dinner.  The  vehicle  of 
infection  was  a  large  pan  of  spaghetti  prepared  by  a  carrier.     This  dish 

^  Women   are  more  subject   to  t;all-stones. 

^Jour.  A.  M.  A.,  June  19,  lOir/,  LXIV,  25,  p.  2051. 

'■Jour.  A.  M.  A.,  Oct.  31,  1914,  LXlll,  IS,  p.  15;J7. 


TYPHOID    FEYEE  93 

was  baked  after  it  had  been  infected,  but  this  baking  was  shown  by 
laboratory  experiments  to  have  incubated  tlie  bacteria  instead  of  dis- 
infecting tlie  food. 

The  Widal  reaction  is  almost  constantly  present  in  the  blood  of 
typhoid  bacillus  carriers.  It  is,  therefore,  of  distinct  value  as  a  pre- 
liminary test  in  the  epidemiological  search  for  carriers.  In  blood  test- 
ing for  this  purpose  dilutions  of  1 :50  and  1 :25,  and  even  a  titer  of  1 :10, 
may  be  used.  The  test  should  be  made  with  both  B.  typhosus  and 
B.  paratyphosus.  The  bacilli  should  then  be  searched  for  in  the  urine 
and  feces  of  those  giving  a  positive  reaction.  It  should  be  remembered 
that  about  90  per  cent,  of  persons  immunized  with  typhoid  vaccine  will 
give  a  positive  reaction. 

The  question  of  preventing  the  spread  of  the  disease  through  bacil- 
lus carriers  is  important  and  ditficult.  Surgical  methods  fail  to  cure 
carriers,  for  the  typhoid  bacillus  may  continue  to  grow  in  other  parts 
of  the  intestinal  tract  than  the  gall  bladder.  Medical  measures,  such  as 
urotropin,  are  efficient  for  bacilluria,  but  are  of  no  avail  in  the  fecal 
carriers.  Attempts  have  been  made  to  relieve  the  condition  by  the  use 
of  bacterial  vaccines.  Petfuschky  ^  and  also  Header  have  reported  en- 
couraging results,  especially  with  the  use  of  autogenous  cultures.  Hek- 
torn  suggests  the  use  of  kaolin,  which  acts  by  adsorption.  So  far  certain 
cases  resist  all  attempts  to  relieve  the  condition.  It  is  unnecessary  to 
place  bacillus  carriers  incommunicado.  It  is  sufficient  to  restrict  their 
activities  so  that  they  cannot  infect  food  or  their  surroundings.  With 
proper  care  and  cleanliness  typhoid  carriers  may  present  little  danger 
to  their  fellow  men.  The  problem,  at  present,  is  to  detect  the  carriers, 
so  as  to  establish  a  sanitary  isolation,  if  not  an  actual  quarantine." 

Resistance  of  the  Virus. — The  typhoid  bacillus  has  no  spore.  It  is, 
therefore,  comparatively  easy  to  destroy.  The  only  difficulty  present- 
ing itself  is  getting  at  the  bacillus  Avhen  imbedded  in  fecal  masses. 
When  dry,  most  typhoid  bacilli  die  in  a  few  hours;  occasionally  a  few 
survive  for  months.  The  fact  that  typhoid  bacilli  are  killed  by  drying 
renders  infection  through  dust  unlikely. 

When  a  moist  medium,  such  as  water,  milk,  or  urine,  is  heated  to 
60°  C,  practically  all  the  typhoid  bacilli  such  a  medium  may  contain 
are  killed.  An  exposure  at  60°  C.  for  20  minutes  will  surely  kill  all 
of  these  microorganisms.  They  are  not  destroyed  by  freezing  (see 
"Eelation  to  Ice,"  pages  948  et  seq.). 

In  their  resistance  to  germicides  typhoid  bacilli  behave  like  the 
average  non-spore-bearing  bacilli.  Thus  bichlorid  of  mercury,  1-1,000; 
phenol,  21/2  per  cent. ;  formalin,   10  per  cent.,  are   effective  upon  the 

^Deut.  med.  Wochschr.,  July  11,  1912,  XXXVIII,  28. 

^  The  facts  covering  the  infectivitv  of  carriers  are  summed  up  hj  Ledinghamj 
39th  An.  Report  Local  Gov.  Board,  1909-10,  Supplement,  p.  249. 


!)4     DISEASES   SPliKAI)   T\\\{i)\jilll   ALVINE    DISCHARGES 

naked  germs.  In  order  to  kill  the  typhoid  bacilli  in  feces  special  pre- 
cautions or  stronger  solutions  are  necessary  (see  pages  10!)  and  1171). 

The  viability  of  typhoid  bacilli  in  feces  is  very  variable,  depending 
on  the  compositioiT  of  the  feces  and  the  varieties  of  other  bacteria 
present.  Sometimes  the  ty})hoid  bacilli  in  feces  ])crisb  in  a  few  hours, 
usually  in  a  day;  under  exceptional  circumstances  they  may  live  for 
much  longer  periods.  In  the  Plymouth  epidemic  typhoid  bacilli  prob- 
ably remained  alive  and  virulent  in  the  feces,  exposed  to  the  winter's 
cold,  for  several  months.  Levy  and  Kayser  found  they  remaijied  alive 
in  feces  for  5  months  in  the  winter.  The  life  of  the  organism  in 
privies  and  in  water  is  usually  comparatively  short.  In  nature  they 
die,  as  a  rule,  in  water  in  about  7  days  and  often  after  48  hours.  They 
probably  live  longer  in  clean  water  than  in  contaminated  water.  In 
the  outer  world  antibiosis  plays  an  important  part,  also  the  presence 
of  deleterious  chemicals,  temperature,  light,  desiccation,  dryness,  and 
other  factors  known  to  be  injurious  to  spore-free  bacteria.  As  a  rule, 
the  typhoid  bacillus  does  not  survive  long  in  the  soil  under  the  usual 
conditions. 

Typhoid  Bacillus  in  Nature.-^The  typhoid  bacillus  should  be  re- 
garded as  a  pathogen,  not  as  a  saprophyte.  It  lives  and  grows  prin- 
cipally in  the  human  body.  It  has  a  tendency  to  die  in  water,  air, 
soil,  upon  fomites,  or  in  nature  generally.  The  grand  exception  to 
this  statement  is  in  the  case  of  milk,  in  which  the  typhoid  bacillus 
grows  well. 

The  typhoid  bacillus  may  live  13  days  in  crude  sewage  (Firth)  ;  14 
days  in  a  septic  tank  (Pickard)  ;  4  months  in  butter  (Bailey  and  Field)  ; 
5  days  in  home-made  cheese  (Heim) ;  12  days  in  pot  cheese  (Lemke)  ; 
39  days  in  ice  cream  (Mitchell).  It  is  destroyed  in  24  hours  in  milk, 
butter-milk,  whey  or  butter  having  an  acidity  of  0.3  to  0.4  per  cent. 

In  endemic  centers  the  typhoid  bacillus  is  much  more  widely  dis- 
tributed in  man  than  the  cases  indicate.  Thus,  in  the  District  of 
Columbia,  of  1,000  healthy  persons  examined  during  the  typhoid  season 
of  1908,  typhoid  bacilli  were  found  in  the  feces  in  3  instances.  At  least 
one  and  perhaps  two  of  these  individuals  were  regarded  as  temporary 
carriers.  In  each  instance  the  organisms  were  found  only  once.  The 
population  of  the  District  of  Columbia  in  1908  was  300,000,  and  at  the 
ratio  of  1  per  1,000  this  would  represent  about  300  healthy  persons  in 
that  community  harboring  and  shedding  typhoid  bacilli  for  a  brief 
period  of  time  during  the  typhoid  season. 

Modes  of  Spread. — Typhoid  fever  is  spread  either  by  direct  or  in- 
direct contact — indirectly  through  water,  milk,  and  other  foods ;  through 
"contacts";  and  also  flies,  fingers,  and  fomites.  Each  of  these  modes 
of  spread  needs  separate  consideration. 

Water. — Water-borne  typhoid  is  a  common  occurrence.     Not  long 


TYPHOID   FEVER:   1902   TO   1916 
Death  Rate  per   100,000  of  Population 


SouHi33(n6,ln6. 

SanAnfonio.Taos 

5fli;annali.6a. 


MewOrkans.La. 
Covington  .Xy. 
Riciimond.Ua. 
LouisuiUe.Ky. 
AHanlrfl.Ga. 


5«af  tie.  Wash. 

EuansuiUe.lni. 

SpringficU.lU. 

Granbftapifts.Wich. 

li)Uminaron,DcL 

lancasfer.Pa. 

HQTri5t»urj,Pa. 

Uttetlmfl.tf.Uo, 


fiinneapous.Minn. 
ToU^  O.Ohio 
Cincinnati, Ohio 
PhUa6clphia,Pa. 
AUcgricnK,Pa. 
PittsbuM  va.. 


ciTy 


Richmond  boToujh.iK.M. 
2u«ns(x)rouflh,flr.Sf. 
cam6en.3f.J. 
lowdinass. 


Unco[n,KtbT. 
Dayton.  Ohio 
Memphis.  TtttB. 


wexuton.rtass. 


HochcstcrA'.y. 

Suracuse.af.y. 

Tall  Riuer,<Has5. 

Brochton.Mass. 

Taunton.Mass. 

Mauerftin.tiass. 

PorHan6,Cle. 

3jlfm.(Mass. 


MilwauKcc.Wis. 
Detroit.  Mich. 
Chicago.  111. 
Buffalo,  itf.y. 
trie.  Pa. 
Clcyelan6,Oliio 
Piiluth  Minn. 


cim 


Fucnburg.Mass. 
camhridge,  Mass. 
SomeruiJie.Mass. 
Worcester,  Mass. 
Bridaeport.Conn. 
Mar(7or6,Conn. 
MaWen.Wass. 
Boston,  aass. 
Chelsea,  Mass. 
!itw  13e6for6,<nass. 
lOaterburjj  eonn. 


Scranton.Pa. 
Portland.  Oreg. 
JohnsfoiDn.Ta. 
Altoona.Pa. 


MolyoKe.^lass. 
Bronx  borough, Af.y. 
Manhattan  t'orough.ar.i*. 
Pawtuckct.n.l. 

3exsa\CU^.N.Z. 
BaUtinorc  Mt, 


St.Paul.Minn. 
(Tanl'on.Oluo 
Broohlyn  Porou^h.X.y. 
Columints.Ohio 
McKCCSport.Va, 


13.9 
20.4 
20. T 
68.9 
tP4..9 


MORRIS  PerCRS  CO.,  WASHINGTON, 


Fig.  12. — Influence  of  Public  Water  Supplies  on  the  Typhoid  Fever  Death  Rate. 
(Diagram  prepared  by  Marshall  O.  Leighton,  U.  S.  Geological  Survey,  from  figures 
furnished  by  Dr.  Cressy  L.  Wilbur,  Chief  Statistician  of  Vital  Statistics,  Bureau  of  the 
Census — from  Kober.) 


96     DISEASES   SPREAD   THROUGH    AI.VINIO    DISCHARGES 

ago  it  was  regarded  as  the  sole  or  usual  mode  of  spread;  now  we  know 
that  this  was  a  mistake.  Most  fecal  matter  ultimately  linds  its  way 
to  water;  most  water  courses  draining  iidiabited  regions  are  contam- 
inated with  human  feces.  Surface  water  is,  therefore,  apt  to  contain 
typhoid  bacilli.  The  fact  that  there  may  be  no  clinical  case  of  typhoid 
fever  in  the  drainage  area  is  no  guarantee  that  the  water  may  not  be 
infected — in  view  of  the  prevalence  of  missed  cases  and  bacillus  carriers. 

Fortunately,  typhoid  bacilli  do  not  grow  and  multiply  in  water 
under  natural  conditions.  They  usually  die  in  a  few  days,  and  rarely 
persist  longer  than  7  days.  They  succumb  more  quickly  in  some  waters 
than  others,  more  quickly  in  summer  than  winter.  Reudiger  ^  has 
shown  that  typhoid  bacilli  disappear  much  more  rapidly  from  polluted 
water  during  the  summer  months  than  during  the  winter  months  Avhen 
the  river  is  protected  with  a  covering  of  ice  and  snow. 

Water  plays  a  large  but  diminishing  role  in  the  spread  of  the 
typhoid  bacillus.  The  great  water-borne  epidemics  have  overshadowed 
the  other  media  of  communication.  We  know  that  the  larger  part  of 
the  typhoid  now  prevalent  in  this  country  is  not  water-borne;  Whipple 
in  1908  estimated  it  at  35  per  cent. ;  it  is  now  probably  less.  Typhoid 
fever  may  be  excessively  prevalent,  even  epidemic,  in  a  city  having  a 
water  supply  of  good  sanitary  quality. 

In  the  vast  majority  of  cases  water-borne  typhoid  is  contracted  from 
a  surface  supply,  that  is,  a  river,  small  stream,  pond,  or  lake.  Ground 
water  becomes  a  source  of  danger  only  under  special  conditions  (see 
chapter  on  water). 

Water-borne  epidemics  present  certain  definite  characteristics.  They 
almost  always  occur  in  the  spring,  fall,  or  winter,  when  the  water 
is  cold.  Most  of  the  great  water-borne  epidemics  have  occurred  in 
northern  cities,  both  in  this  country  and  in  Europe.  They  usually 
have  a  sharp  onset,  the  curve  rises  to  a  peak,  and  declines  rapidly. 
The  pollution  is  usually  nearby;  that  is,  there  is  a  rather  direct  trans- 
fer of  fresh  virulent  infection.  Granting  that  the  typhoid  bacillus 
does  not  grow  in  cold  water,  there  must  be  a  very  considerable  dilution 
in  most  of  the  epidemics. 

The  following  examples  are  given  of  the  fact  that  water-borne 
outbreaks  of  typhoid  fever  occur  during  the  winter,  fall,  or  early 
spring,  when  the  water  is  cold.  Thus  we  have  the  water-borne 
epidemic  in  Plymouth,  Penn.,  in  1885,  which  began  with  the  spring 
thaw  and  doubtless  came  from  the  frozen  accumulation  of  typhoid 
excrement  from  a  single  case.  Very  similar  to  the  Plymouth  out- 
break was  that  at  New  Haven,  Conn.,  in  1901.  The  outbreak  at 
Ithaca,  N.  Y.,  started  in  epidemic  proportions'  in  January.  The  epi- 
demic in  Sherbourne,  England,  in  1873,  likewise  started  in  January. 
^Jour.  Am.  Pub.  Health  Assn.,  June,  1911,  Vol.  I,  No.  16,  p.  411. 


TYPHOID    FEVER 


97 


Four  acute  epidemic  exacerbations  are  recorded  in  Philadelphia  in  De- 
cember of  the  years  1884,  1890,  1899,  and  1903.  Several  similar  epi- 
demics have  occurred  in  the  winter  time  in  Chicago — one  in  January, 
1890,  another  in  January,  1896,  and  one  in  March,  1891.  Another 
striking  instance  is  the  epidemic  in  Newark,  N".  J.,  in  February,  1899, 
and  one  in  December  1891.  Abroad,  epidemics  are  recorded  in  Ber- 
lin in  February,  1899,  in  Paris  in  February,  1894,  and  in  Vienna  in 
November,   1888.      All   of  these   are   generally   believed  to   have   been 


Pittsburgh.  Pa.  ■ 

-Typh 

010  Fev 

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Death  kau  pur  100.000  — /900  to  1910. 

1900 

1901 

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Fig.  13. — Immediate  and  Striking  Effect  of  Purifying  a  Badly  Infected  Water 
Supply  upon  the  Typhoid  Situation. 

water-borne  and  must  have  taken  place  when  the  water  was  very  cold. 

In  fact,  as  previously  pointed  out,  extensive  water-borne  epidemics  of 

typhoid  fever  rarely  occur  in  the  summer  time. 

The  epidemiology  of  water-borne  typhoid  caused  by  distant,  diluted 

and  attenuated  infection  is  not  understood.     It  was  formerly  thought 

that  a  high  typhoid  rate  necessarily  meant  badly  infected  water.     We 

know  now  that  this  does  not  necessarily  follow,  as  has  been  proven  by 

the   experiences    in   Washington,   Winnipeg,   army   camps,   and    many 

southern  cities. 


98     DISEASES   SPREAD   THEOUGIT    ALVT^^p^   DISCHARGES 

Almost  all  the  water-borne  epidemics  of  typhoid  fever  rest  up(jn  cir- 
cumstantial evidence.  It  is  difficult  to  isolate  the  typhoid  bacillus  from 
watei;,  and  the  damage  is  usually  done  before  suspicion  points  to  the 
water.^ 

It  is  clear  that  in  cities  which  have  had  safe  water  supplies  for  a 
period  of  years  the  typhoid  death  rate  should  not  be  above  5  per  100,000, 
unless  some  unusual  conditions  exist,  such  as  poor  control  of  milk  or 
lack  of  control  .over  patients  and  carriers,  and  disregard  of  modern  sani- 
tary knowledge. 

No  single  measure  in  reducing  typhoid  fever  on  a  large  scale  ap- 
proaches the  effect  of  substituting  a  safe  for  a  polluted  water  supply.  As 
an  instance  of  this  wholesale  saving  of  human  life,  the  reduction  of 
typhoid  fever  in  four  American  cities  is  shown  in  Fig.  14. 


Q          aO         4.0        6  0         80        lOO       120        140        |60       IBO        {100         \ 

1003  H 

1904.  H 

1905 

!■■ 

WaUrTowa.JOr. 

1906 

^ 

1992 

■ 

1893 

r 

1894 

Liawrcnc<2,Miss. 

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1996 

1998 

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r 

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AlbaiivjKr 

1901 

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1908 

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CinciTmatiu  Otiio. 

Fig.   14. 


-Abrupt  "Reduction  in  Death  Rates  prom  Typhoid  Fever  Incident  to 
Water  Purification  in  Four  American  Cities. 


Column  X. 


-The  Black  Squares  Indicate  Raw  Water  and  the  Clear  Squares  Filtered 
Water. 


Ice. — Ice  may,  under  exceptional  circumstances,  occasionally  be  the 
vehicle  by  which  typhoid  bacilli  are  transferred.  Freezing  does  not  kill 
B.  typhosus,  but  there  is  a  great  quantitative  reduction  not  only  in  the 
act  of  freezing,  but  during  storage,  hence  the  danger  is  greatly  lessened. 
The  most  suggestive  outbreak  of  typhoid  fever  attributed  to  ice  was 
reported  by  Hutchins  and  Wheeler  in  1903  in  the  St.  Lawrence  Hospital, 
three  miles  below  Ogdensburg.     A  few  other  instances  in  which  ice  is 


^  Examples  of  water-borne  outbreaks  of  typhoid  fever  will  be  found  in  the 
chapter  on  water. 


TYPHOID    FEVER  99 

believed  to  have  conveyed  the  infection  have  been  reported,  but  are  based 
upon  flimsy  evidence.  The  fact  that  natural  ice  is  usually  stored  many 
weeks  or  months  before  it  is  used  is  a  sanitary  safeguard.  Manufactured 
ice  made  from  distilled  water  and  handled  with  cleanly  methods  is  above 
reproach.  For  a  discussion  of  ice  in  relation  to  typhoid  fever  and  other 
infections  see  page  948  et  seq. 

Milk. — Trask  collected  317  typhoid  epidemics  up  to  1908  caused  by 
infected  milk.  Since  then  many  more  instances  have  come  to  light. 
Doubtless  many  milk  outbreaks  have  escaped  attention  or  have  been 
attributed  to  water  or  other  sources.  The  typhoid  bacillus  grows  well 
in  milk,  and  it  is  now  realized  that  this  medium  is  a  frequent  and 
important  mode  of  communication.  Most  milk  outbreaks  are  reported 
from  England  or  America.  On  account  of  the  almost  universal  custom 
of  boiling  the  milk  in  European  and  tropical  countries,  milk  outbreaks 
are  rarely  reported  from  these  regions.  During  the  four  years'  study  of 
typhoid  fever  in  Washington,  it  was  found  that  at  least  10  per  cent,  of 
the  cases  were  milk-borne. 

The  milk  usually  becomes  contaminated  on  the  farm,  from  a  case 
or  a  carrier.  It  may  also  become  infected  in  transportation,  at  the  city 
dairy,  or  in  the  home.  Milk  outbreaks  come  abruptly,  rise  to  a  peak  like 
a  water  epidemic,  and  subside  rather  sharply.  There  are  comparatively 
few  secondary  cases.  Milk-borne  epidemics  of  typhoid  fever  have  certain 
characteristics  which  permit  ready  recognition. 

(a)  There  is  a  special  incidence  of  the  disease  on  the  track  of  the 
implicated  milk  supply.     The  outbreak  is  localized  to  such  areas. 

(b)  The  better  class  of  houses  are  invaded,  and  persons  in  better  cir- 
cumstances generally  suffer  most. 

(c)  Those  who  drink  milk  are  chiefly  affected  and  those  suffer  most 
who  are  large  consumers  of  raw  milk. 

(d)  The  incidence  is  high  among  M^omen  and  children. 

(e)  The  incubation  period  is  shortened  perhaps  on  account  of  the 
large  amount  of  infection  taken. 

(f)  More  than  one  case  occurs  simultaneously  in  a  house.  This  is  a 
very  suspicious  circumstance  to  the  epidemiologists.  The  first  indication 
of  a  milk  outbreak  in  a  city  with  a  good  water  supply  is  usually  the  fact 
that  two  or  more  persons  in  a  household  came  down  with  typhoid  fever 
within  a  few  days  of  each  other. 

(g)  Clinically  the  disease  may  run  a  mild  course,  owing  to  the  fact, 
no  doubt,  that  the  virus  becomes  attenuated  in  the  process  of  multiplica- 
tion in  the  milk.  In  water-borne  typhoid  the  same  germs  are  ingested 
that  were  passed;  in  milk-borne  typhoid  it  may  be  the  succeeding  gen- 
erations that  are  ingested. 

Milk-borne  outbreaks  are  sometimes  very  extensive.  One  of  the 
largest  epidemics  occurred  in  Boston   (Jamaica  Plain)    in  March  and 


100      DISEASES   SPREAD   THIIOUGU    ALViXK    I)IS(niAll(;KS 

April,  1908.  Four  liuiidred  and  ten  cases  were  reported;  ;54<S  of  them 
drank  the  suspected  milk.  Among  the  first  victims  of  the  disease  was 
the  milkman,  who  was  believed  to  have  infected  the  milk  through  tasting 
it.  The  number  of  persons  involved  in  a  milk-borne  epidemic  varies 
greatly,  depending  upon  the  amount  of  milk  infected  and  other  factors. 
It  must  not  be  uncommon  for  a  sijigle  bottle  of  milk  or  a  small  quantity 
to  become  infected,  and  thus  transmit  the  disease  to  ojie  or  two  persons. 
Such  instances  are  exceedingly  difficult  to  trace.  Ofttijnes  ih(;  milk 
becomes  infected  from  a  carrier.  An  instance  of  this  occnrred  in  Wnsh- 
ington  (Georgetown)  in  1908.  In  tliis  case  liie  milkmaid  hud  typhoifl 
fever  18  years  previously.  Examinations  showed  almost  pure  culture  of 
B.  typhosus  in  her  feces.  Fifty-five  persons  who  drank  the  infected  milk 
contracted  the  disease. 

Milk  Products. — Fresh  milk  products,  such  as  cream,  ice  cream, 
butter,  and  buttermilk,  and  fresh  cheese,  may  contain  the  typhoid  bacil- 
lus, and  are  occasionally  media  of  communication. 

Cream  contains  more  bacteria  than  the  milk  from  which  it  is  taken. 
The  use  of  infected  cream  in  coffee,  on  cereals,  etc.,  is  sufficient  to  cause 
the  disease.  Several  instances  in  the  Washington  studies  were  traced 
to  such  use  of  cream.  As  a  rule,  coffee  in  the  cup  is  hot  enough  to  kill 
the  typhoid  bacillus. 

Freezing  kills  only  a  certain  percentage  of  the  typhoid  bacilli.  In 
Washington  several  cases  of  the  disease  were  traced  to  ice  cream. 

Bruck  has  shown  that  the  typhoid  bacillus  will  live  in  butter  for  27 
days. 

Buttermilk  may  be  quite  as  dangerous  as  the  cream  from  w^iich  it 
is  derived.  An  acidity  of  0.3  to  0.4  per  cent,  is  said  to  kill  the  typhoid 
bacillus  in  24  hours,  but  this  work  is  not  confirmed  and  the  results 
doubtful.  In  cheese  the  time  of  fermentation,  antibiosis,  etc.,  lessens 
the  likelihood  of  survival  of  the  typhoid  bacillus.  Fresh  cream  cheese, 
such  as  Cottage  cheese,  may  be  responsible  for  an  occasional  case. 

Oysters,  Mussels,  and  Shellfisk. — The  first  outbreak  of  typhoid 
fever  attributed  to  this  source  was  investigated  by  Conn  at  Wesleyan 
University,  Middletown,  October,  1894.  Twenty-five  cases  were  attrib- 
uted to  eating  infected  oysters;  4  died.  Not  all  of  those  who  took  sick 
had  clinical  typhoid  fever.  Some  had  gastro-intestinal  disturbances  with 
illness  lasting  but  a  few  days.  About  one-quarter  of  those  attending  the 
dinners  at  which  the  oysters  were  served  were  made  ill. 

A  similar  instance  occurred  at  the  Mayors'  banquets  at  South  Hamp- 
ton and  Winchester,  in  1903. 

Dr.  L.  W.  Darra  Mair  ^  showed  that  much  of  the  typhoid  fever  in 
Belfast,  Ireland,  from  1897  to  1901,  was  due  to  eating  cockles  and  mus- 
sels taken  from  sewage  polluted  water.     The  amount  of  the  fever  dimin- 

M'roc.  Roy.  Soc.  Epidomiology  Sec,  April,  1909,  Vol.  II,  Part  2. 


TYPHOID    FEVEE  101 

ished  markedly  and  its  seasonal  prevalence  was  changed  by  betterment  of 
the  shellfish  situation. 

In  Brighton,  England,  Dr.  J.  T.  C.  Nash  ^  proved  that  much  of  the 
typhoid  fever  in  the  Borough  of  Southhead-on-Sea  prior  to  1899  was  due 
to  infected  oysters.  There  was  a  sharp  reduction  in  the  amount  of  fever 
when  the  fore  shore  fisheries  were  stopped,  and  almost  a  cessation  of  all 
cases  when  attention  was  given  to  all  shellfish,  including  the  improved 
laying  and  cooking  of  cockles. 

In  the  Washington  studies  it  seems  that  oysters  and  shellfish  play  a 
minor  role  in  the  spread  of  the  disease,  which  occurs  mostly  in  the  sum- 
mer time,  while  oysters  and  similar  sea  food  are  relished  mainly  in  winter. 
Comparatively  few  of  the  cases  studied  gave  a  history  of  having  eaten 
oysters  within  30  days  prior  to  the  onset  of  the  disease.  Oysters  become 
dangerous  when  consumed  soon  after  taking  them  from  a  polluted  bed, 
or  when  floated  or  bloated  in  infected  water.  (For  further  discussion  of 
this  topic,  see  page  636.) 

Fruits  and  Vegetables. — Vegetables,  such  as  celery,  lettuce,  water 
cress,  and  radishes,  partaken  of  raw,  and  grown  on  land  fertilized  with 
fresh  night  soil,  may  be  dangerous,  and  this  probably  accounts  for  an 
occasional  case.  In  large  cities  it  is  practically  impossible  to  trace  this 
source  of  infection.  It  therefore  remains  more  a  suspicion  than  a  convic- 
tion. In  Springfield,  Mass.,  an  outbreak  which  occurred  in  the  summer 
of  1905  was  attributed  to  infected  fruits  and  vegetables. 

At  a  wedding  breakfast  in  Philadelphia  June  24th,  with  43  guests  in 
attendance,  19  persons  ate  watercress  sandwiches.^  Eighteen  of  these 
were  ill  July  32nd  with  typhoid  fever,  only  2  of  them  being  in  Phila- 
delphia at  the  time,  while  the  other  16  were  scattered  in  suburban  terri- 
tory and  in  summer  resorts  along  the  Atlantic  Coast  as  far  north  as 
Maine.  The  watercress  had  been  secured  from  a  farm  on  which  the 
sanitary  conditions  were  quite  unsatisfactory.  A  similar  outbreak  oc- 
curred in  Hackney,  London,  in  1903,  although  the  evidence  in  that  out- 
break was  not  so  convincing.  Morse  ^  reports  an  outbreak  presumably 
due  to  celery. 

Creel  *  found  typhoid  bacillus  upon  the  tips  of  leaves  of  plants  culti- 
vated in  contaminated  soil.  Under  conditions  most  unfavorable  to  the 
B.  typhosus  the  infection  lasted  at  least  31  days — a  period  sufficiently 
long  for  some  varieties  of  lettuce  and  radishes  to  mature. 

Flies. — The  evidence  is  now  complete  that  the  common  house  fly 
(Musca  domestica)  may  convey  the  infection  of  typhoid.  It  is  not  inap- 
propriately called  the  typhoid  fly.     The  typhoid  bacilli  may  be  smeared 

*Proc.  Eoy.  Soc.  Epidemiology  Sec,  April,  1909,  Vol.  II,  Part  2. 

''Engineering  News,  Aug.    14,    1913. 

^Report  State  Board  of  Health  of  Mass.,   1899,  p.  751. 

*  Public  Health  Reports,  Feb.  9,   1912,  p.   187,  XXVII,  6. 


mi      DISKASKS   SlMtl^^AI)   'rilUOTKJJf    ALVINK    blSCHAIlCES 

upon  the  feet  or  other  parts  of  the  insect,  or  may  live  in  tlie  intestinal 
tract  and  pass  in  the  dejecta  in  almost  pure  culture.  Flies  live,  feed, 
and  breed  in  fecal  matter  and  decomposing  organic  substances  of  all 
kinds.  It  is  easy  to  see  how  they  may  convey  infections  from  this  source 
to  our  food,  lips,  or  fingers.  Alice  Hamilton  isolated  typhoid  bacilli  from 
5  out  of  18  house  flies  captured  in  Chicago  in  the  privy  and  on  a  fence 
near  a  sick  room.  It  has  been  shown  experimentally  that  living  typhoid 
bacilli  may  remain  upon  the  bodies  of  flies  for  as  long  as  23  days.  Special 
attention  to  the  role  played  by  the  fly  was  given  by  Reed,  Vaughan,  and 
Shakespeare  in  their  studies  of  the  prevalence  of  typhoid  fever  in  our 
army  camps  in  1898.  They  concluded  that  flies  undoubtedly  served  as 
carriers  of  the  infection  and  attributed  about  15  per  cent,  of  the  cases 
to  this  mode  of  communication.  They  found  that  "flies  swarm  over 
infected  fecal  matter  in  the  pits  and  then  deposit  it  and  feed  upon  the 
food  prepared  for  the  soldiers  at  the  mess  tents.  In  some  instances, 
where  lime  had  recently  been  sprinkled  over  the  contents  of  the  pits,  flies 
with  their  feet  whitened  with  lime  were  seen  walking  over  the  food.^' 
The  danger  from  fly  transmission  varies  very  much,  and  depends  upon 
.  circumstances.  In  a  camp  it  is  considerable ;  in  a  well  sewered  city  the 
risk  is  diminished.  In  our  Washington  studies  we  could  find  no  relation 
between  fly  abundance  in  the  summer  of  1908  and  typhoid  prevalence.  It 
is  not  possible  to  express  mathematically  the  percentage  of  cases  caused 
by  flies — the  figures  would  vary  greatly,  depending  upon  circumstances. 
The  danger  of  typhoid  from  flies  in  cities  has  doubtless  been  overstated. 
However,  if  only  one  per  cent,  of  the  cases  were  thus  transmitted,  the 
suppression  of  flies  would  still  be  quite  worth  while  (page  247). 

Dust. — Typhoid  bacilli  soon  die  when  dried,  especially  when  exposed 
to  the  sun  and  air.  Dust-borne  infection  in  this  disease  must  be  rare. 
In  the  South  African  war  there  were  frequent  dust  storms  in  some  local- 
ities, so  that  the  food  was  covered  with  dust  and  sand.  Some  of  the  infec- 
tion was  believed  to  have  been  conveyed  in  this  way. 

FoMiTES. — The  infection  may  be  conveyed  upon  soiled  linen,  blankets, 
and  other  objects.  It  was  believed  by  Eeed,  Vaughan,  and  Shakespeare 
that  the  clothing,  blankets,  and  tents  in  the  Spanish- American  war  be- 
came infected  and  were  a  prime  factor  in  spreading  the  disease.  After 
the  South  African  war  some  of  the  blankets  used  by  the  troops  were  sent 
back  to  England  and  used  on  a  training  ship,  on  which  typhoid  fever 
appeared.  The  blankets  were  found  to  be  dirty  and  soiled  with  fecal 
matter,  from  which  Klein  is  reported  to  have  obtained  living  typhoid 
bacilli.  The  danger  of  fomites  contaminated  with  fresh  infection  is  real, 
and  emphasizes  the  importance  of  disinfecting  bedding,  towels,  handker- 
chiefs, body  linen,  and  other  fabrics. 

Soil. — The  soil,  long  regarded  as  the  most  important  factor  in  the 
spread  of  typhoid  fever,  and  by  Pettenkofer  and  others  considered  an 


TYPHOID    FEVER  103 

essential  element,  is  now  iiiveii  scant  consideration.  Pollution  of  the 
soil,  however,  cannot  Ije  disregarded.  The  typhoid  bacillus  may  live  for 
a  long  time  in  sewage-soaked  earth.  A  polluted  soil  may  endanger  the 
water,  milk,  and  other  foods,  or  infect  through  flies  and  other  means 
(see  Soil). 

Contact  Ixfectiox. — ^"Contact"  is  a  convenient  term  to  indicate  the 
spread  of  infection  directly  or  indirectly  as  a  result  of  close  association 
between  the  sick  and  the  sound.  Actual  contact  is  not  necessarily 
implied.  The  term  is  used  to  indicate  the  transfer  of  the  infection 
through  a  short  intervening  space  in  a  brief  period  of  time  (see  page 
367).  Thus  the  infection  may  be  passed  from  one  to  another  through 
kissing,  soiled  hands,  remnants  of  food,  infected  thermometers,  or  tongue 
depressors,  contaminated  towels  or  other  fabrics,  cups,  spoons,  glasses, 
etc.  If  the  nurse  infects  a  cup  of  milk  or  glass  of  water  that  carries  the 
infection  to  another  member  of  the  household,  such  cases  are  included 
under  "contacts."  The  infection  may  also  be  spread  in  the  household  by 
flies,  fingers,  and  various  other  means^  usually  difficult  to  trace,  and 
which  are,  therefore,  all  included  under  this  group.  Regarded  in  this 
light,  contacts  play  a  large  role  in  the  spread  of  the  disease. 

Extensive  municipal  outbreaks  have  been  reported  as  largely  or  en- 
tirely due  to  contact  infection.  Winslow  in  1901  studied  such  an  out- 
break in  iSTewport.  Others  have  been  reported  from  Knoxville,  Winnipeg, 
Springfield,  and  from  Germany  and  England.  Koch  regarded  the  spread 
of  typhoid  in  Trier  in  the  light  of  contact  infection.  Freeman  says  that 
the  majority  of  outbreaks  in  the  smaller  to^Tis  of  Virginia  are  due  to 
this  cause.  Extensive  outbreaks  in  institutions  are  often  due  to  contact 
with  mild  cases  or  carriers.  Flies,  fingers,  and  food  (Sedgwick),  and 
dirt,  diarrhea,  and  dinner  (Chapin),  which  too  often  get  sadly  confused, 
explain  the  occurrence  of  many  a  case  of  contact  infection  in  typhoid 
fever  as  well  as  other  infections. 

In  army  camps  with  clean  water  and  good  milk,  contact  infection  may 
rise  to  epidemic  proportions.  In  the  Spanish- American  war,  of  107,000 
of  our  troops  in  camp,  20,000  contracted  typhoid,  mostly  by  "contact." 
Similar  conditions  prevail  in  rapidly  growing  cities,  in  crowded  apart- 
ments, and  congested  regions  with  a  susceptible  population  and  other 
favoring  conditions.  The  danger  of  contact  is  well  shown  by  the  fre- 
quency with  which  nurses,  ward  attendants,  house  physicians,  and  others 
similarly  exposed  take  typhoid  fever.  Studies  of  the  incidence  of  the 
disease  in  the  Massachusetts  General  Hospital,  Boston,  in  the  Presby- 
terian Hospital,  Philadelphia,  and  the  Johns  Hopkins  Hospital,  Balti- 
more, show  that  typhoid  fever  is  at  least  twice  and  may  be  8  times  as 
prevalent  among  those  who  come  in  close  and  frequent  association  with 
the  patient  as  among  the  population  at  large.  Further,  the  disease  con- 
tracted under  such  conditions  seems  to  run  a  course  of  more  than  ordinary 


104      DISEASES   SPliEAD   THROIKMI    AEVINK    IMSCIIAIKJKS 

severity,  with  a  greater  number  of  complications  aiifJ  with  a  liigli  mor- 
tality. This  is  doubtless  due  largely  to  the  fact  that  the  contactors  receive 
fresh  virulent  virus. 

In  our  studies  of  typhoid  fever  in  Washington  we  were  impressed 
with  the  importance  and  frequency  of  contact  infection  in  that  endemic 
center.  In  1907  we  attributed  6  per  cent,  of  the  cases  to  contacts;  in 
1908,  15  per  cent.,  and  in  1909,  17  per  cent.  This  included  only  contact 
with  cases  during  the  febrile  stage  of  the  disease.  In  Strassburg,  Kayser 
attributed  16.8  per  cent,  of  the  cases  occurring  during  3  years  in  that 
city  to  contact  infection.  Little  groups  of  4,  6,  to  12  or  more  cases  fol- 
lowing a  primary  case  in  a  suburban  focus,  in  my  experience,  frequently 
fall  in  the  category  of  contacts. 

According  to  Conradi,  the  infection  is  transmissible  most  often  during 
the  early  stages  of  the  disease,  sometimes  even  during  the  period  of 
incubation. 

The  Washington  studies  do  not  support  this  view,  for  we  found  the 
disease  is  communicated  during  all  stages,  and  especially  during  con- 
valescence. This  may  be  due  to  the  fact  that  during  this  time  the  patient 
moves  about  and  scatters  the  infection  over  a  wider  radius. 

Typhoid  fever,  in  view  of  all  the  facts,  must  now  be  regarded  as  a 
"contagious"  disease.  We  will  never  have  an  end  of  it  until  it  is  so 
regarded  and  treated  accordingly. 

Preventive  Typhoid  Inoculations. — An  active  immunity  to  typhoid 
fever  may  be  artificially  induced  by  introducing  dead  typhoid  bacilli  into 
the  subcutaneous  tissue.  The  procedure  is  harmless,  rational,  and  effec- 
tive. 

Our  knowledge  of  inoculations  against  typhoid  fever  began  with  the 
work  of  Pfeiffer  and  Kolle,^  who  inoculated  two  volunteers  in  1896. 
About  the  same  time  Almroth  Wright  ^  inoculated  several  persons,  and 
in  1898  continued  the  work  upon  an  extensive  scale  in  India  upon  4,000 
British  soldiers.  In  1900,  during  the  Boer  war,  Wright,  together  with 
Leishman,  prepared  a  vaccine  ^  and  supervised  the  inoculation  of  100,000 
British  troops.  The  results  in  India  were  quite  encouraging,  but  for 
various  reasons  the  same  procedure  in  South  Africa  was  not  as  satisfac- 
tory as  had  been  anticipated.  Prophylactic  inoculation  on  the  advice  of 
Koch  was  used  by  the  Germans  in  the  Herero  campaign  in  southern  West 
Africa  in  1904.  The  prophylactic  was  voluntary  and  only  about  half  of 
the  command  (7,287  men)  availed  themselves  of  it.  The  results,  while, 
good,  fell  short  of  expectations.  In  this  country  Richardson  was  the  first 
to  advocate  and  practice  inoculations  as  a  means  of  protection  against 

*  Pfeiffer  and  Kolle:     Deutsche  med.  Wochnschr.,  1896,  XXII,  735. 

=  Wright:  Lancet,  London,  Sept.  19,  1890.  807;  Brit.  Med.  Jour.,  Jan.  ,30, 
1897,  16. 

^  The  material  injected  is  called  a  vaccine  and  the  process  spoken  of  as  vacci- 
nation.    The  term  in  this  connection  is  a  little  confusing. 


TYPHOID    FEVEE 


105 


typhoid  fever.    The  best  results  have  been  obtained  in  the  United  States 
Army  under  the  direction  of  Major  Eussell. 

Leishman^  in  his  Harben  lecture  (1910)  explains  the  lack  of  success 
in  early  years  by  saying  that  the  vaccine  may  have  been  made  less  efficient 
by  the  use  of  too  great  heat  in  killing  the  bacilli.  Further,  it  should  be 
noted  that  smaller  doses  and  fewer  injections  were  given  then  than  now. 

The  typhoid  vaccines  may  be  prepared  in  a  number  of  different  ways. 
Usually  dead  bacilli  are  used,  although  live  bacilli  have  been  inoculated. 
The  bacilli  may  be  killed  either  with  the  aid  of  heat  or  germicidal  sub- 
stances ;  the  dead  or  live  bacilli  may  be  sensitized  by  the  addition  of  anti- 
typhoid serum ;  the  vaccines  may  be  prepared  with  pulverized  bacilli,  from 
bacillary  extracts,  or  by  the  use  of  various  chemical  methods. 

Usually  the  vaccine  is  made  from  a  twenty-four-hour-old  culture 
killed  by  heating  to  53  °  C.  for  thirty  minutes.  OverliiBating  probably 
impairs  the  immunizing  power  of  the  vaccine.  ]\iost  typhoid  bacilli  die 
before  the  temperature  reaches  G0°  C.  Some  of  the  strains  have  a  lower 
thermal  death  point.  Stone  heats  only  to  53°  C.  for  one  hour,  depending 
upon  phenol  (0.5  per  cent.)  to  sterilize  the  culture.  Cultures  killed 
without  heat  have  perhaps  greater  protective  properties. 

Certain  strains  seem  to  cause  the  production  of  more  antibodies  than 
others.  In  the  earlier  work  it  was  believed  that  the  more  virulent  strains 
produce  a  greater  protection.  This  is  doubtful,  for  it  appears  that  the 
protection  afforded  is  not  in  proportion  to  the  local  or  febrile  reaction, 
but  to  the  amount  and  variety  of  antibodies  stimulated. 

The  injections  are  given  subcutaneously  at  intervals  of  five  days. 
From  500,000,000  to  1,000,000,000  dead  typhoid  bacilli  are  injected  at 
each  inoculation.  The  number  of  inoculations  varies  with  different 
authorities.  At  least  3,  preferably  4,  should  be  given;  the  greater  the 
number  of  injections  the  greater  the  immunity  induced. 

The  reactions  are  usually  moderate  and  never  serious.  They  consist 
of  local  manifestations ;  irritation,  and  inflammation  about  the  site  of 
inoculation,  such  as  pain,  redness,  swelling,  edema;  also  general  symp- 
toms, such  as  malaise,  pains  in  the  back  and  limbs,  and  fever.  The  num- 
ber and  character  of  the  reactions  in  the  experience  of  the  United  States 
Army  -  are  shown  in  the  following  table  : 


Number  of 
doses 

Reaction, 
Absent 

Reaction, 
Mild 

Reaction, 
Moderate 

Reaction, 
Severe 

45,680 
44,321 
38,902 

68.2% 
71.3% 
78.0% 

28.9% 
25.7% 
20.3% 

2.4% 
2.6% 
1.5% 

0.3% 

0.2% 

0.1% 

^Leishman,  W.  B.:     Jour.  Roy.  Inst.  Puh.  Health,  London,  1910,  XVIII,  394. 
^Russell,  F.  F.:     Jour.  A.  M.  A.,  LVIII,  No.  18,  May  4,  1912. 


106      DISEASES   SPEEAD   THROUGH   ALVINE   DISCHARGES 

Children,  as  a  rule,  react  less  than  adults.  Of  1,101  persons  inocu- 
lated by  Hartsock,  11  per  cent,  showed  no  reaction,  83  per  cent,  mild 
reaction,  5  per  cent,  a  moderate  reaction,  and  1  per  cent,  a  severe  reac- 
tion. There  is  always  some  local  tenderness  and  redness  at  the  point  of 
inoculation.    The  symptoms  of  the  reaction  usually  pass  in  24  hours. 

The  best  time  to  give  the  treatment  is  late  in  the  afternoon,  for  then 
the  severest  part  of  the  reaction  is  over  by  the  morning.  The  injections 
are  usually  given  into  the  subcutaneous  tissue  of  the  outer  side  of  the 
arm  or  into  the  abdominal  wall ;  sometimes  the  interscapular  space. 

There  is  no  laboratory  index  of  the  degree  or  duration  of  the  immu- 
nity produced  as  a  result  of  the  inoculations.  The  following  antibodies 
appear  in  the  blood :  agglutinins,  precipitins,  opsonins,  lysins,  stimulins. 
There  are  factors  involved  in  the  immunity  not  understood,  and  there- 
fore, the  subsequent  development  of  typhoid  fever  among  individuals 
protected  in  this  manner  is  the  only  index  of  value. 

The  negative  phase  advanced  by  Wright  and  denied  by  Leishman  and 
others  probably  does  not  occur.  At  least  there  appears  to  be  no  increased 
susceptibility  to  the  disease  during  the  so-called  negative  phase.  There 
is,  therefore,  no  known  objection  to  giving  the  prophylactic  to  those 
exposed  to  the  disease  or  during  an  epidemic.  In  fact,  the  typhoid  vac- 
cines have  been  used  as  a  therapeutic  agent  during  the  fever. 

The  immunity  varies  in  degree  and  also  in  duration ;  at  least  one  year 
(Pfeiffer  and  Kolle's  vaccine)  ;  four  years  (Wright's  vaccine).  On  the 
average,  the  immunity  may  probably  be  depended  upon  for  2  or  3  years 
when  produced  by  4  injections  of  dead  bacilli.  The  immunity  may  be 
prolonged  or  renewed  by  recourse  to  reinoculation.  One  attack  of  typhoid 
fever,  however  mild,  produces,  as  a  rule,  a  lasting  immunity.  Second 
attacks,  however,  occur.  Draschfeld's  figures,  based  on  2,000  persons  in 
the  Antwerp  Hospital,  show  that  only  0.7  per  cent,  of  that  number  were 
affected  twice.  This  percentage  is  doubtless  too  high,  for  the  figures  were 
collected  before  our  knowledge  of  paratyphoid  infections.  The  typhoid 
vaccines  do  not  protect  against  paratyphoid  infections,  and  contrariwise 
paratyphoid  does  not  protect  against  typhoid. 

The  best  results  have  been  obtained  in  the  United  States  Army,  where 
the  vaccinations  are  done  under  the  supervision  of  Major  Russell.^ 

During  1913  the  army  had  only  two  cases  of  typhoid  in  the  enlisted 
force  of  over  80,000  men.  One  of  these  occurred  in  a  man  who  had  not 
been  vaccinated ;  the  other  was  among  the  troops  in  China.  He  had  been 
immunized  in  1911  and  the  history  of  the  case  is  in  doubt.  In  six 
years,  1909  to  1914,  there  was  only  one  death  from  typhoid  in  the  U.  S. 
Army,  while  the  rate  in  the  country  at  large  averaged  over  16.5  per  hun- 
dred thousand. 

The  health   record   established   by   the   Maneuver   Division   of   the 

^Jour.  A.  M.  A.,  Aug.  30,  1913. 


TYPHOID    FEVER 


lor 


TABLE  3.- 


-TYPHOID,  1901-1912,  FOR  THE  WHOLE  ARMY,  AT  HOME  AND  ABROAD— 
OFFICERS  AND  ENLISTED  MEN 


Mean 
Strength 

Cases 

Deaths 

Occurring 
Among  Those 

Year 

Number 
of 

Ratios  per 

1,000  of 

Mean 

Strength 

Number 
of 

Ratios  per 

1,000  of 

Mean 

Strength 

Per   Cent 

of  Total 

Cases 

Who  Were 
Vaccinated 

Cases 

Deaths 

1901 

81,885 
80,778 
67,643 
67,311 
65,688 
65,159 
62,523 
74,692 
84,077 
81,434 
82,802 
88,478 
80,766 
87,228 

552 

565 

348 

293 

206 

373 

237 

239 

282 

198 

70 

27 

4 

7 

6.74 

6.99 

5.14 

4.35 

3.14 

5.72 

3.79 

3.20 

3.35 

2,43 

.85 

.31 

.04 

0.07 

74 
69 
30 
23 
20 
18 
19 
24 
22 
14 
8 
4 

3 

.88 
.85 
.44 
.33 
.30 
.27 
.30 
.31 
.26 
.17 
.10 
.044 

0.03 

13.0 

12.2 

8.6 

7.8 

9.7 

4.8 

8.0 

10.0 

7.8 

7.1 

11.4 

14.8 

42.8 

1 
7 
11 
8 
2 
1 

1902 

1903 

1904 

1905 

1906 

1907 

1908 

1909* 

1910^ 

19111 

1912 

0 
0 
1 
0 

1913 

0 

1914 

0 

^Typhoid  vaccination  was  voluntary  during  1909  and   1910,  and  until  Sept. 
30,  1911,  when  it  was  made  compulsory  for  officers  and  men. 


United  States  Army  at  San  Antonio,  Texas,  during  the  summer  of  1911, 
is  a  triumph  in  preventive  medicine.  The  division  had  a  mean  strength 
of  12,801  men.  All  were  treated  with  the  typhoid  vaccines.  The  result 
was  that  from  March  10th  to  July  10th  only  two  cases  of  typhoid  fever 
developed;  no  deaths.  One  patient  was  a  private  of  the  hospital  corps 
who  had  not  completed  his  immunization,  having  taken  only  two  doses. 
His  case  was  very  mild  and  probably  would  have  been  overlooked  but  for 
the  rule  that  blood  cultures  were  made  in  all  cases  of  fever  of  over  48 
hours'  duration.  The  other  case  was  a  teamster  who  had  not  been  inocu- 
lated. Among  the  12,801  men  there  were  only  11  deaths  from  all  dis- 
eases. Typhoid  fever  prevailed  at  the  time  in  the  neighborhood.  Thus, 
there  were  49  cases  of  typhoid  fever  with  19  deaths  in  the  city  of  San 
Antonio  during  this  period.  This  contrasts  markedly  with  the  typhoid 
record  of  the  United  States  Army  during  the  Spanish-American  war, 
when-  the  typhoid  record  of  a  division  of  volunteer  troops  camped  at 
Jacksonville,  Florida,  in  1898,  under  conditions  similar  to  those  at  San 
Antonio,  was  as  follows:  The  division  at  Jacksonville  had  2,693  cases 
with  248  deaths,  which  was  about  the  average  typhoid  incidence  of  the 
camps, 

The  U.  S.  Navy  had  only  seven  cases  among  50,000  men  during  the 
year  ending  June,  1913.     Four  of  these  occurred  among  men  treated  at 


lOS      D1SBASP:S   SPEEAD   through   ALVINK   D]S(JJ1AI{(JKS 

a  tropical  station,  where  tlie  vaccine  had  deteriorated.     All  the  cases  were 
mild.    In  1911  the  rate  was  3.G1  per  1,000. 

Spooner  reports  that  in  the  Massachusetts  General  Hospital,^  among 
the  nurses  and  others  exposed  to  typhoid  fever,  80  per  cent,  of  whom  have 
been  inoculated  during  the  past  three  years,  not  a  case  has  been  con- 
tracted, and  for  the  first  year  in  the  history  of  the  institution  (1912) 
there  were  no  cases  among  the  nurses  or  attendants.  The  case  morbidity 
in  training  schools  for  nurses  in  ]\Iassacliusetts  during  three  years  was 
nearly  nine  times  greater  in  the  uninoculated  than  among  the  inocu- 
lated. 

Metchnikoff  and  Besredka  -  failed  to  protect  chimpanzees  against 
typhoid  infection  by  means  of  killed  bacilli,  but  obtained  immunity 
apparently  as  definite  as  that  produced  by  an  attack  of  the  disease  by  the 
use  of  living  cultures.^ 

Summary — The  results  of  typlioid  inoculations  can  no  longer  bo 
questioned.  Tlie  morbidity  is  lowered  in  tliose  who  have  been  properly 
"vaccinated."  Tlie  most  striking  effect  is  in  the  lowering  of  the  mor- 
tality.* Preventive  typhoid  inoculations  involve  no  risk  whatever,  and 
are  especially  applicable  to  those  unduly  exposed  to  the  infection, 
such  as  nurses,  hospital  attendants,  pliysicians,  travelers,  soldiers  in 
camps,  persons  in  epidemic  localities,  and  persons  in  the  family  of  a 
bacillus  carrier.  The  method  has  been  proposed  for  general  use  among 
the  public  in  endemic  foci,  but  it  is  a  question  whether  this  artificial 
method  of  acquiring  immunity  would  serve  as  good  a  purpose  in  the  end 
as  fighting  the  disease  along  the  lines  of  general  sanitation — which  has 
been  so  successfully  done  in  many  European  centers.  It  would  certainly 
be  a  mistake  to  immunize  the  population  with  this  artificial  method  to 
the  neglect  of  general  sanitary  improvements,  such  as  good  water,  clean 
milk,  fly  suppression,  cleanliness,  and  personal  hygiene.  Because  a  per- 
son has  received  the  protection  afi^orded  by  typhoid  inoculations  is  no 
reason  for  reckless  disregard  of  other  prophylactic  measures. 

Management  of  a  Case  so  as  to  Prevent  Spread. — Success  depends 
upon  an  early  and  accurate  diagnosis.  All  cases  of  typhoid  fever  and 
all  cases  suspected  of  being  typhoid  fever  should  be  isolated.  This  does 
not  mean  imprisonment  in  a  lazaretto.  The  proper  place  to  care 
for  typhoid  fever  is  in  a  suitable  hospital.  A  private  home  is  a  poor 
makeshift  for  a  hospital,  and  it  is  unreasonable  to  turn  a  household 
into  a  hospital  for  4  to  8  weeks  or  longer.     The  room  in  which  the 

*  Transactions  of  the  Assn.  of  Amer.  Pliysicians,  1912. 
''Ann.  de  VInst.  Pasteur,  Dec,  1911,  XXV,  12,  p.  865. 
"Ann.  de  VInst.  Pasteur,  Mar.  25,  1911,  and  Dec,   1911. 

*  See  the  svnnming  Up  of  the  antityphoid  inoculations,  by  Leishman,  in  the 
July  and  September,  1910,  numbers  of  the  Journal  of  the  Royal  Institute  of  Pub- 
lic Health,  xviii,  Nos.  7,  8,  and  9 ;  also  Report  of  the  French  Commission,  Public 
Health  Reports,  P.  H.  &  M.  H.  S.,  October  6,  1911,  xxvi,  40,  1507. 


TYPHOID    FEVEE  109 

patient  is  treated  should  be  large  and  well  ventilated,  and  should 
contain  no  unnecessary  furniture,  curtains,  carpets,  etc.  It  must  be 
kept  scrupulously  clean,  dry  sweeping  and  dusting  prohibited;  and  well 
screened. 

The  case  should  be  reported  to  the  health  authorities  without  delay, 
and  the  house  should  be  placarded  so  as  to  warn  others,  and  visiting  dis- 
couraged. Under  no  circumstances  should  visitors  be  admitted  into  the 
sick  room. 

The  disinfection  of  the  stools,  urine,  ^sputum,  and  other  excretions  is 
of  the  first  importance,  and  should  be  carried  out  with  great  care  and 
conscientiousness.  For  the  urine,  sufficient  bichlorid  may  be  added  to 
make  a  1-1,000  solution,  or  carbolic,  2.5  per  cent.,  or  formalin,  10  per 
cent.,  and  allowed  to  stand  one  hour  before  discarding.  Stools  may  be 
disinfected  with  bleaching  powder,  3  per  cent.;  milk  of  lime  (1  to  8)  ; 
cresol,  1  per  cent. ;  carbolic  acid,  5  per  cent. ;  formalin,  10  per  cent. ;  or 
unslaked  lime  and  hot  water.  (Page  1171.)  The  discharges  should  be 
received  in  a  glass  or  earthenware  vessel  containing  some  of  the  germi- 
cidal solution.  Then  add  more  of  the  solution  so  that  it  shall  be  present 
in  twice  the  volume  of  the  excreta  to  be  disinfected;  disintegrate  the 
masses  thoroughly  and  let  stand  at  least  one  hour,  protected  from  flies. 
Masses  are  so  difficult  to  penetrate  that  they  must  be  broken  up  thor- 
oughly with  a  wooden  paddle.  It  takes  a  strong  carbolic  solution  12 
hours  to  penetrate  the  interior  of  a  small  fecal  mass ;  larger  masses  are 
impenetrable  to  most  germicides. 

The  sputum  may  be  burr.cd  or  boiled.  Strong  carbolic  acid,  cresol, 
or  formalin  are  also  applicable. 

The  patient  should  have  his  own  dishes,  cups,  spoons,  glasses,  etc., 
which  should  be  scalded  after  each  use.  Kemnants  of  lunch,  especially 
meat,  milk,  gelatin,  broths,  and  other  organic  food  in  which  the  infection 
may  live  and  even  grow  should  not  be  eaten  by  others.  Such  remnants 
may  be  burned  or  first  boiled  and  then  discarded.  Those  who  nurse  the 
sick  should  keep  out  of  the  kitchen  on  account  of  the  risk  of  contam- 
inating the  food. 

Towels,  sheets,  nightgowns,  and  all  fabrics  used  about  the  patient 
should  be  disinfected  either  by  boiling,  or  immersion  for  one  hour  in 
bichlorid  of  mercury,  1-1,000,  carbolic  acid,  2.5  per  cent.,  or  cresol,  or 
liquor  cresolis  compositus  1  per  cent. 

The  water  used  to  bathe  the  patient  should  be  disinfected  before  it  is 
allowed  to  run  into  the  sewer.  This  may  be  done  by  heat  or  by  adding 
sufficient  carbolic  acid  or  bleaching  powder;  the  latter  is  cheapest  and 
most  practical. 

Milk  bottles  must  be  kept  out  of  the  sick  room.  In  any  case,  they 
should  be  scalded  before  returning  to  the  dairy. 

The  thermometer  should  be  kept  in  formalin,  alcohol  or  other  suitable 


110      DISEASES   SPEEAD   THIJOIKMI   ALVIXK    DISCHAEGES 

germicidal  solution.  Eectal  tul)es,  especially  in  liospital  practice,  must 
be  carefully  disinfected  each  time  before  using. 

The  nurse  must  protect  herself  as  well  as  others;  a  solution  of 
bichlorid  should  be  kept  constantly  at  hand.  Every  time  the  patient  is 
bathed;,  his  mouth  cleaned,  or  his  buttocks  washed,  the  hands  must  be 
disinfected  and  washed  in  soap  and  water.  The  nurse  must  exercise 
especial  care  if  she  is  to  go  to  the  kitchen  or  to  the  ice-box,  etc.,  as  is 
frequently  the  case  in  private  houses,  where  a  special  diet  kitchen  cannot 
be  provided.  The  nurses,  physicians,  ward  attendants,  and  others  par- 
ticularly exposed  may  protect  themselves  with  preventive  typhoid  inocu- 
lations. The  physician  should  be  quite  as  careful  as  the  nurse,  not  only 
so  that  he  may  not  carry  the  infection  to  himeslf  or  other  patients,  but 
also  that  his  practice  may  serve  as  a  stimulating  example. 

At  the  conclusion  of  the  case  a  general  disinfection  and  cleansing  of 
the  room  and  its  contents  should  be  practiced. 

Convalescents  should  not  be  given  liberty  until  the  danger  of  bacillus 
carrying  has  passed.  This  may  be  determined  only  by  bacteriologic  exam- 
inations of  the  stools  and  urine.  Four  successive  negative  results  at  inter- 
vals of  several  days  are  required  before  a  report  may  be  vouchsafed  in  the 
case  of  the  stools.  In  Sawyer's  case  frequent  examination  extending  over 
a  period  of  4  months  proved  negative,  yet  the  carrier  subsequently  in- 
fected 3  persons.    One  examination  of  the  urine  is  ordinarily  sufficient. 

The  use  of  urotropin  (hexamethylenamin)  diminishes  the  incidence 
of  bacilluria,  and  is  becoming  a  routine  practice. 

Summary — Personal  Prophylaxis. — The  prevention  of  typhoid  fever 
may  be  summed  up  in  the  word  cleanliness — ^physical  and  biological 
cleanliness.  By  this  is  meant  not  only  clean  food,  especially  water  and 
milk,  but  also  cleanliness  of  person  and  environment.  Typhoid  fever  has 
always  prevailed  where  cleanliness  is  neglected  and  has  diminished  where 
it  has  been  intelligently  observed.  It  is  true  that  typhoid  bacilli  do  not 
breed  in  the  rubbish  and  dirt  of  back  yards  and  alleys,  or  in  unkempt 
city  lots,  but  these  conditions  in  a  city  may  be  taken  as  an  index  of  the 
general  cleanliness  of  its  inhabitants. 

The  eradication  of  typhoid  fever  is  easier  in  cities  than  in  country 
districts;  clean  cities  now  have  less  typhoid  fever  than  the  surrounding 
rural  region.  Cities  can  well  afford  extensive  and  expensive  sanitary 
works  which  are  beyond  the  financial  possibilities  of  sparsely  settled  dis- 
tricts. If  a  clean  water  from  natural  sources  is  not  available,  then  large 
volumes  of  a  polluted  water  may  be  rendered  reasonably  safe  for  munici- 
pal use  by  slow  sand  filtration  and  by  bleaching  powder.  Further,  cities 
can  afford  to  inspect  their  milk  supply  and  to  supervise  the  pasteurization 
of  all  that  is  not  safe.  These  two  measures  would  practically  eliminate 
typhoid  infection  coming  into  cities  in  its  food  supply — especially  if  in 
addition  to  this  a  supervision  is  maintained  over  oysters  and  shellfish. 


TYPHOID    FEVEE  111 

«nd  vegetables  partaken  in  their  raw  state.  Further,  cities  can  well  afford 
to  employ  skilled  and  experienced  health  officials  and  are  financially  able 
to  engage  the  services  of  experts.  On  the  other  hand,  each  farmhouse 
represents,  in  miniature,  all  the  problems  with  which  the' city  deals  by 
wholesale,  and  is  often  not  financially  able  to  meet  its  sanitary  require- 
ments. The  country  is  the  weakest  link  in  our  sanitary  chain.  The 
good  results  obtained  in  the  rural  region  of  Yakima,  Washington,  and  in 
several  counties  of  Maryland  by  Lumsden,  through  intelligent  and  in- 
tensive measures,  are  a  great  object  lesson  in  rural  sanitation. 

Cities  will  find  it  a  paying  proposition  to  suppress  flies,  rats,  and 
other  vermin,  which  may  be  done  much  more  easily  than  in  rural  or 
suburban  conditions.  This  should  be  done  not  only  on  account  of  the 
suppression  of  typhoid  fever,  but  other  diseases  thus  conveyed.  The  city 
beautiful  must  also  be  the  city  clean  in  its  cellars,  garrets,  back  yards, 
empty  lots,  alleys,  and  stables. 

To  sum  up,  the  main  factors  in  the  spread  of  typhoid  fever  in  our 
large  cities  are :  (1)  water;  (2)  milk;  (3)  contact;  (4)  miscellaneous. 
In  a  city  having  a  clean  water  supply  the  residual  typhoid  must  be 
attacked  along  two  definite  lines,  viz.,  improvement  of  the  milk  supply 
and  its  pasteurization,  and  a  warfare  against  the  disease  in  the  light  of 
an  infection  spread  from  man  to  man. 

The  health  officer  should  establish  a  laboratory  for  the  early  diagnosis 
of  cases  and  for  the  discovery  of  carriers.  The  health  officer  should  at 
once  send  a  trained  agent  to  every  house  from  which  a  case  of  typhoid 
fever  is  reported.  The  visit  should  be  made  as  early  as  practicable  and 
with  the  object  of  seeing  that  the  stools  and  urine  are  properly  disin- 
fected, patients  isolated,  milk  bottles  scalded,  sick  rooms  screened,  house 
placarded,  visiting  discouraged,  and  other  necessary  measures  taken  to 
prevent  the  spread  of  the  infection.  Convalescents  should  not  be  released 
until  the  absence  of  typhoid  bacilli  from  the  urine  and  stools  has  been 
demonstrated  by  at  least  four  successive  examinations.  Carriers  need  not 
be  indefinitely  quarantined,  but  should  be  prohibited  from  engaging  in 
any  employment  having  to  do  with  foods,  or  in  which  close  personal  con- 
tact, as  in  nursing,  is  required.  Carriers  should  be  instructed  concerning 
the  danger  and  educated  to  thoroughly  wash  and  disinfect  their  hands, 
especially  after  a  visit  to  the  toilet. 

The  health  officer  alone  cannot  eliminate  typhoid  fever  from  a  city. 
He  needs  the  help  of  the  community.  Much  can  be  done  through  educa- 
tion. A  stimulating  leader  may  accomplish  a  world  of  good  through 
voluntary  effort,  but  in  the  end  it  requires  comprehensive  laws  and  an 
energetic  enforcement  of  them,  without  fear  or  favor. 

The  personal  prevention  of  typhoid  fever  resolves  itself  into  boiling 
the  water,  if  suspicious;  partaking  only  of  milk  or  fresh  milk  products 
that  have  been  pasteurized,  and  otherwise  assuring  oneself  that  all  food 


113      DISEASES   SPEEAD   THROUGH   ALVINK   JJJSCHAKGES 

has  been  thoroughly  cooked.  In  addition  to  this,  direct  and  indirect  con- 
tact with  persons  who  have  the  disease,  or  who  are  known  to  be  carriers, 
must  be  avoided.  Sanitary  habits  should  be  encouraged,  especially  the 
one  simple  precaution  of  washing  the  hands  after  defecation  and  before 
eating,  and  of  keeping  the  fingers  and  other  unnecessary  objects  away 
from  the  mouth  and  nose.  Finally  the  protection  afforded  through 
typhoid  inoculations  may  be  used. 


CHOLERA 

The  prevention  of  cholera  corresponds  to  the  prevention  of  typhoid 
fever.  In  the  case  of  cholera  vigorous  measures  have  been  rewarded  with 
signal  success.  It  is  quite  possible  to  live  in  the  midst  of  a  raging  cholera 
epidemic  without  contracting  the  disease.  Within  recent  years  epidemics 
have  been  suppressed  and  the  spread  of  the  infection  limited. 

The  home  of  true  cholera  is  the  delta  of  the  Ganges,  hence  it  is  usually 
called  "Asiatic  cholera"  to  distinguish  it  from  Cholera  nostras  or  Cholera 
morbus.  During  the  sixteenth,  seventeenth,  and  eighteenth  centuries 
cholera  was  epidemic  at  various  times  in  India.  It  is  only  in  the  nine- 
teenth century  that  cholera  has  spread  along  the  routes  of  trade  and 
travel  to  Europe  (first  in  1830),  Africa,  and  America  in  1832.  There 
have  been  four  pandemics;  one  from  1817  to  1823,  another  1826  to  1837, 
a  third  1846  to  1862,  and  a  fourth  from  1864  to  1875.  In  1832  it  entered 
the  United  States  by  way  of  New  York  and  Quebec  and  reached  as  far 
west  as  the  military  posts  of  the  upper  Mississippi.  The  disease  recurred 
in  1835  and  1836.  In  1848  it  entered  the  country  through  New  Orleans 
and  spread  widely  up  the  Mississippi  and  was  dragged  across  the  conti- 
nent by  the  searchers  for  gold  all  the  way  to  California  (1849) .  It  again 
prevailed  widely  through  this  country  in  1854,  having  been  introduced 
by  immigrant  ships  into  New  York.  In  1866  and  1867  there  were  less 
extensive  epidemics.  In  1873  it  again  appeared  in  the  United  States,  but 
did  not  prevail  widely.  In  1892  the  great  epidemic  of  Hamburg  occurred, 
and  the  disease  threatened  to  become  pandemic  in  Asia,  Africa,  and 
Europe.  Cases  were  brought  by  transatlantic  liners  to  New  York,  and 
a  few  cases  occurred  in  the  city,  but  its  spread  was  prevented  by  aggres- 
sive measures.  Cholera  has  prevailed  for  years  in  the  Philippines,  but  is 
now  under  control.  While  the  home  of  cholera  is  in  the  tropics,  there  is 
scarcely  a  country  in  the  world  that  has  not  been  visited  some  time  or 
other  by  the  ravages  of  this  fatal  disease. 

The  incubation  period  of  cholera  is  short,  frequently  1  or  2  days, 
rarely  over  5.  The  period  of  detention  in  quarantine  is  5  days.  One 
attack  produces  a  mild  grade  of  immunity  which  is  not  lasting.  The 
disease  is  peculiar  to  man. 


CHOLERA  113 

The  Cause  and  Contributing  Causes  of  Cholera. — The  Vibrio  cholerae 
or  the  "comma  bacillus''  of  Koch  is  the  undisputed  cause  of  the  disease. 
The  conditions  of  infection,  however,  are  complex.  Not  everyone  who 
takes  the  specific  microorganism  by  the  mouth  necessarily  gets  the  dis- 
ease, but  without  it  there  can  be  no  cholera.  Many  cholera  vibrios  prob- 
ably die  in  the  acid  juices  of  the  stomach.  There  is,  therefore,  perhaps 
less  danger  in  taking  small  amounts  of  infection  during  active  digestion 
than  upon  an  empty  stomach,  for  it  has  been  shown  experimentally  that 
cold  drinks  do  not  stay  long  in  an  empty  stomach,  but  pass  quickly 
through  the  pylorus.  After  the  cholera  vibrio  has  passed  the  pylorus  and 
reaches  the  alkaline  juices  of  the  intestines,  it  may  find  ideal  conditions 
for  growth  or  may  still  have  a  hard  struggle  for  existence.  Here  sym- 
biosis or  antibiosis  must  play  a  dominant  role.  It  is  well  known  in  all 
cholera  epidemics  that  a  deranged  digestion  is  an  important  predisposing 
factor  to  the  disease.  In  the  Hamburg  epidemic  a  marked  access  of  cases 
on  Monday  following  the  Sunday  dissipations  was  noted.  Eaw  fruits, 
crude  fibrous  vegetables,  and  other  fermentable  food,  difficult  of  diges- 
tion, seem  to  favor  the  growth  and  multiplication  of  the  cholera  vibrio 
in  the  intestinal  tract.  In  the  light  of  this  view  raw  fruits  and  vegetables 
may  often  be  the  predisposing  factor  rather  than  the  medium  which 
conveys  the  infection.  Just  what  the  factors  are  that  favor  or  handicap 
the  growth  of  the  cholera  vibrio  in  the  intestinal  tract  are  undetermined. 
Pettenkofer  stoutly  maintained  that  the  "comma  bacillus"  was  only  one 
of  the  factors  in  the  etiology  of  the  disease.  He  placed  special  impor- 
tance upon  the  condition  of  the  host  and  his  environment,  and  considered 
at  least  three  fundamental  factors  in  his  X,  Y,  Z  theory.    X  is  the  germ, 

Y  the  host  or  soil,  Z  the  environment.  In  this  connection  disease  may 
aptly  be  compared  to  fermentation,  in  which  X  represents  the  yeast,  Y 
the  carbohydrate,  and  Z  the  temperature,  moisture,  reaction,  and  other 
essential  conditions  for  the  growth  and  activity  of  the  yeast.  Pettenkofer 
maintained  that  X  without  Y  and  Z  would  not  produce  cholera,  that  is, 
while  the  cholera  vibrio  was  pathogenic  in  India  or  Hamburg  (1892), 
where  Y  and  Z  were  favorable,  it  would  be  harmless  in  Munich,  where 

Y  and  Z  were  unfavorable.  To  prove  this  theory,  he  and  his  assistant, 
Emmerich,  drank  pure  cultures  of  cholera  after  first  rendering  the 
stomach  contents  alkaline.  Pettenkofer,  then  an  old  man,  had  a  diar- 
rhea; Emmerich,  on  the  other  hand,  had  a  sharp  attack  from  which  he 
almost  lost  his  life.  Similar  convincing  experiments  have  occurred 
among  laboratory  workers,  who  have  accidentally  gotten  pure  cultures  of. 
cholera  into  their  mouths.  On  the  other  hand,  a  number  of  persons  who 
imitated  Pettenkofer's  experiment  were  not  affected.  Pettenkofer  did 
not  regard  his  own  case  as  cholera,  and  insisted  that  the  inconclusive  re- 
sults lent  confirmation  to  his  theory  of  the  importance  of  contributing 
factors  (Y  and  Z). 


114     DISEASES   SPliEAD   THROUGH   ALVINE   DISCHARGES 

Diagnosis. — The  diagnosis  of  cliolera  depends  upon  isolation  and 
identiiicatiou  of  the  cholera  vibrio  in  pure  culture.  This  has  become 
comparatively  simple,  but  great  care  must  be  taken  Jiot  to  confuse  the 
true  vibrio  of  cholera  with  a  great  host  of  other  microorganisms  which 
closely  resemble  it.  , 

A  presumptive  diagnosis  of  cholera  may  be  made  by  finding  large 
numbers  of  comma-shaped  bacilli  in  direct  microscopic  examination  of 
stained  preparations,  or  in  hanging  drops  of  the  mucous  flakes  ordinarily 
found  in  cholera  stools.  This  test  is  only  presumptive,  the  final  criterion 
being  the  biological  reactions  of  the  microorganism  obtained  in  pure 
culture.  The  two  reactions  which  are  specific  and  reliable  are  Pfeiffer's 
phenomenon  and  agglutination. 

Dependence  should  not  be  placed  upon  morphological  characters,  cul- 
tural peculiarities,  or  pathogenicity  upon  laboratory  animals,  for  these 
do  not  furnish  the  means  of  certainly  defining  the  cholera  vibrio.  For 
the  isolation  of  the  cholera  vibrio,  agar  is  preferable  to  gelatin,  formerly 
so  much  used.  The  suspected  material  should  be  planted  upon  the  sur- 
face of  ordinary  alkaline  agar  or  upon  Dieudonne's  medium,  using  one 
of  the  small  rice-like  flakes  or  an  equivalent  quantity  of  feces. 

Dieudonne's  medium  is  prepared  as  follows : 

Sol.  A. — Equal  parts  of  a  normal  solution  of  potassium  hydroxid  and 
defibrinated  ox-blood  are  mixed  and  sterilized  in  the  autoclave. 

Sol.  B. — Ordinary  nutrient  agar,  exactly  neutral  to  litmus. 

Seven  parts  of  B  are  mixed  with  3  parts  of  A  and  poured  into  Petri 
dishes.  The  plates  should  not  be  used  immediately  after  their  prepara- 
tion. Dieudonne  recommends  keeping  them  several  hours  in  the  incu- 
bator at  37°  C,  uncovered  and  face  down,  or  to  heat  them  for  5  minutes 
at  65°  C.  Equally  good  results  can  be  obtained  by  keeping  them  48 
hours  at  room  temperature.  The  surface  of  the  agar  should  be  slightly 
dry.  Once  in  condition,  the  plates  should  be  used  in  a  period  not  exceed- 
ing 5  or  6  days. 

Upon  this  medium  cholera  vibrios  grow  abundantly.  On  the  con- 
trary, the  organisms  which  most  often  accompany  them  on  plate  cul- 
tures, especially  B.  coli,  grow  either  very  poorly  or  not  at  all. 

When  it  is  suspected  that  the  cholera  vibrios  are  few  in  number,  they 
may  be  enriched  by  first  planting  in  Dunham's  solution.  Approximately 
1  c.  c.  of  fecal  matter  should  be  placed  in  50  c.  c.  of  the  peptone  solution. 
This  is  incubated  at  37°  C,  and  in  from  6  to  8  hours  a  loopful  is  taken 
from  the  surface  and  transferred  to  ordinary  agar  or  Dieudonne's. 
medium.  Suspicious  colonies  are  fished  and  studied  further.  A  quick 
method  of  detecting  carriers  is  given  on  page  108.^ 

Kolle  and  Gotchlich  have  shown  from  a  large  number  of  observations 

*  Some  New  Selective  Cholera  Media.  Goldberger,  Hyg.  Lab.  Bull.j  91^ 
P.  H.  S. 


CHOLERA  115 

that  with  strongly  aggiutinativo  serum,  the  power  of  which  reaches 
1-4,000,  the  agglutinative  power  for  common  vibrios,  not  cholera,  does 
not,  as  a  general  rule,  exceed  1-50  and  rarely  reaches  1-200 ;  agglutination 
in  dilutions  of  1-500  has  been  only  very  exceptionally  observed.  On  the 
contrary,  the  true  cholera  vibrios  agglutinate  in  dilutions  varying  from 
1-1,000  and  1-20,000.  Therefore,  with  a  specific  agglutinating  serum 
having  a  titer  of  1-4,000,  any  organism  which  is  agglutinated  in  1-1,000 
may  be  considered  true  cholera.  Organisms  agglutinating  in  dilutions 
of  1-500  should  be  regarded  as  doubtful. 

In  any  critical  case  Pfeiffer's  reaction  (see  page  441)  should  be  tried. 
This  is  specific.    See  also  page  118. 

Modes  of  Transmission. — Cholera  is  spread  by  man  from  place  to 
place.  It  follows  the  lines  of  trade  and  travel.  Seaports  are  invariably 
first  attacked.  The  epidemic  at  Hamburg  in  1892  was  brought  to  that 
port  by  immigrants  on  board  vessels  from  Russia.  There  are  many  sim- 
ilar instances.  In  1849  many  a  gold  hunter  found  another  Eldorado 
than  the  one  he  was  searching  for,  as  cholera  was  dragged  across  the  con- 
tinent by  the  caravans  seeking  fortunes  in  California.  The  same  thing 
takes  place  in  the  Indian  pilgrimages  to  Mecca. 

The  cholera  vibrio  enters  the  digestive  tract  through  the  mouth.  It 
is  taken  in  the  food  and  drink.  Infected  water  is  a  frequent  medium  of 
transference,  and  probably  the  sole  vector  of  the  great  epidemic  outbursts. 
Cholera,  however,  may  be  transferred  from  man  to  man  directly,  also 
indirectly  by  flies,  fingers,  food,  and  all  the  innumerable  channels  from 
the  anus  of  one  man  to  the  mouth  of  another  that  have  been  described 
in  the  case  of  typhoid. 

In  endemic  or  residual  cholera,  water-borne  infection  plays  a  minor 
role.  This  was  well  proven  in  the  recent  sanitary  campaign  against  the 
disease  in  the  Philippine  Islands,  in  which  the  water  was  practically 
ignored  and  the  disease  conquered  in  the  light  of  a  contact  infection  com- 
municated rather  directly  from  man  to  man.  Cholera  was  spreading 
rapidly  despite  active  measures.  Its  progress  was  stopped  by  throwing  a 
sanitary  corps  across  a  narrow  neck  of  land  some  miles  in  advance  of  the 
march  of  the  disease.  Here  a  quarantine  was  established  and  persons 
held  5  days  under  observation  before  they  were  permitted  to  pass.  The 
usual  disinfection  and  other  measures  were  practiced  and  the  disease 
effectively  stopped.     , 

The  cholera  vibrio  leaves  the  body  in  enormous  numbers  in  the 
dejecta,  also  sometimes  in  the  matter  vomited.  The  cholera  vibrio  does 
not  invade  the  blood  and  tissues  generally,  and,  therefore,  is  not  voided 
in  the  urine.  Disinfection  in  this  disease  must,  therefore,  be  concentrated 
upon  the  discharges  from  the  bowels  and  mouths,  at  the  bedside. 

Water. — The  cholera  vibrio  may  live  and  even  multiply  in  water. 
Koch  in  his  original  investigations  found  the  oro;anism  in  the  foul  water 


1U;      DISEASES    SPREAD   TIIIfOTT(JIT    ATAHXF.   DTSCHAROES 

of  a  tank  in  India  which  was  used  by  the  natives  for  drinking  ])uri)oses. 
It  has  been  shown  by  experiment  that  the  cholera  vibrio  may  multiply  to 
some  extent  in  sterilized  river  water  or  well  water;  and  that  it  preserves 
its  vitality  in  such  water  for  several  weeks  or  even  months.  In  recent 
times  cholera  organisms  have  been  foinid  not  infrequently  in  the  water 
of  wells,  water  mains,  rivers,  harbors,  canals,  and  even  sea  water  (the 
Korth  Sea  near  the  mouth  of  the  Elbe),  which  have  become  contam- 
inated with  the  discharges  of  cholera  patients.  It  is  plain  from  the 
nature  of  the  case  that  infected  water  must  play  a  very  large  role  in 
spreading  this  infection. 

The  earliest  and  now  classic  instance  in  favor  of  the  water-borne 
theory  we  owe  to  the  late  Dr.  John  Snow.  This  is  the  well-known  Broad 
Street  pump  outbreak  in  London  in  1854,  an  account  of  which  will  be 
found  on  page  925. 

The  best  example  of  water-borne  cholera  is  the  Hamburg  epidemic  of 
1892,  which  I  was  fortunate  enough  to  see  in  part.  In  this  case  no  link 
in  the  chain  of  evidence  is  missing.  Cholera  was  brought  to  Hamburg 
by  immigrants  either  from  Eussia  or  France.  The  water  of  the  Elbe  was 
infected  with  their  discharges.  The  Vibrio  cholerae  was  readily  isolated 
from  the  river  water  which  was  distributed  throughout  the  city  for  drink- 
ing purposes  without  purification.  The  sewers  of  Hamburg  emptied  into 
the  river  Elbe  near  the  water  intake,  which  produced  an  increased  con- 
centration of  the  infection.  An  account  of  the  epidemic  will  be  found 
on  page  929. 

Other  Modes  of  Transeerence.; — The  fact  that  water-borne  infec- 
tion is  practically  the  only  cause  of  the  large  cholera  epidemics  must  not 
overshadow  the  importance  of  other  modes  of  transmission.  In  addition 
to  the  violent  outbreaks,  cholera  occurs  in  nests  or  smoulders  like  endemic 
typhoid.  It  is  difficult  to  trace  the  connection  between  cases  in  endemic 
areas.  Thus,  a  careful  study  of  the  cholera  situation  in  Manila  disclosed 
the  fact  that  isolated  cases  would  crop  up  at  widely  different  points  with- 
out any  evident  connection  between  them.  Cholera  carriers  were  sus- 
pected and  later  demonstrated.  At  irregular  intervals  of  several  years 
the  disease  would  gather  force,  and  cases  multiply,  until  it  assumed 
epidemic  proportions,  it  is  believed  entirely  independent  of  the  water 
supply.  The  way  cholera  was  dragged  across  our  continent  by  the  "forty- 
niners,"  and  its  occurrence  among  the  Mecca  pilgrims,  are  instances  of 
its  spread  largely  independent  of  infected  water. 

Contact  Infection. — Contact  infection  in  cholera  must  not  be 
underestimated.  Persons  frequently  become  infected  through  handling 
the  dejecta  or  through  freshly  infected  fomites,  such  as  soiled  linen. 
Direct  transmission  from  person  to  person  was  formerly  seen  among 
physicians  and  nurses.  In  congested  quarters,  where  many  persons  live 
under  uncleanly  conditions,  contact  infection  plays  an  important  part. 


CHOLEKA  117 

The  same  thing  may  be  seen  on  board  vessels;  in  which  case  the  disease 
may  be  confined  to  the  firemen,  stewards,  or  some  other  limited  group 
who  are  required  to  live  in  close  contact  with  each  other.  Epidemic  out- 
breaks due  to  contact  infection  have  been  recorded,  such  as  the  30  cases 
which  occurred  in  the  fall  of  1892  in  Boizenburg. 

Cholera  is  not  highly  "contagious,"  for  physicians,  nurses,  and  others 
in  close  contact  with  patients  need  not  become  infected  jirovided  intelli- 
gent measures  are  adopted.  On  the  other  hand,  there  is  great  danger  of 
the  spread  of  the  disease  through  devious  and  hidden  routes,  as  is  the 
case  with  typhoid  and  dysentery.  Washerwomen  and  those  who  are 
brought  in  very  close  contact  with  the  linen  of  cholera  patients  or  with 
their  stools  may  contract  the  disease.  Koch,  in  his  original  inves- 
tigations, found  that  the  "comma  bacillus''  may  multiply  rapidly  upon 
the  surface  of  moist  linen. 

Milk  may  be  contaminated,  but  is  proljably  not  a  frequent  medium 
of  infection,  for  the  reason  that  its  acid  reaction  is  inimical  to  the  chcjlera 
vibrio.  Green  vegetables  and  fruit  that  have  been  washed  in  an  infected 
water  may  convey  the  disease.  The  bacilli  may  live  on  fresh  bread,  but- 
ter, and  meat  for  from  6  to  8  days,  if  not  too  acid. 

Flies,  Etc. — It  has  been  shown  that  the  cholera  vibrios  may  live  in 
the  intestines  of  flies  for  at  least  3  days,  and  these  and  other  insects  may 
also  spread  the  infection  mechanically.  The  cholera  vibrio  is  a  frail 
organism  and  dies  rapidly  when  dried  or  exposed  to  light  and  other 
injurious  influences.  Infection  through  the  air  is,  therefore,  not  to  be 
dreaded.  Fomites,  such  as  bed  and  body  linen  or  other  objects,  including 
floors,  walls,  toys,  etc.,  contaminated  with  the  dejecta,  can  be  regarded  as 
possible  sources  of  infection.  There  is,  however,  a  special  limitation  in 
this  case,  owing  to  the  fact  that  this  organism  is  so  readily  destroyed  by 
desiccation  and  crowded  out  by  saprophytic  microorganisms.  Thus,  as  a 
rule,  only  fresh  dejecta  and  freshly  contaminated  objects  are  liable  to 
convey  the  infection. 

Bacillus  Caeeiees. — The  cholera  vibrios  are  passed  in  the  feces 
during  the  early  part  of  the  disease.  They  usually  disappear  after  the 
fourth  to  the  fourteenth  day,  but  may  remain  a  much  longer  time. 

McLoughlin  found  bacillus  carriers  numerous  in  epidemic  centers. 
Thus  he  found  6  to  7  per  cent,  of  carriers  among  healthy  individuals 
living  in  the  infected  neighborhoods  in  Manila.  On  the  other  hand,  car- 
riers were  exceedingly  rare  in  neighborhoods  having  few  cases.  Persons 
in  good  health  may  harbor  the  cholera  organism  in  their  intestines. 
Cholera  carriers,  therefore,  play  a  similar  role  to  typhoid  carriers  in 
spreading  the  infection.  Carriers  are  the  principal  factor  in  the  spread 
of  endemic  cholera  and  they  keep  the  infection  alive  in  the  Philip- 
pines, India  and  other  places  where  there  is  little  or  no  water-borne 
infection. 


118       DISEASES  SPEEAD  Tl [ROUGH  ALVINE  DISCHARGES 


In  the  outbreak  of  cholera  in  Manila,  1914,  carriers  were  the  most 
numerous  and  also  the  most  insidious  source  of  infection.^  The  follow- 
ing data  was  collected  by  Pfeiffer.^ 

PERSISTENCE  OF  CHOLERA  VIBRIOS  IN  STOOLS  OF  CONVALESCENTS,  OR  BACILLUS 

CARRIERS 


Name  of  Observer 


Guttman 

Lazarus  and  Pulicke 

Michailow 

Simonds 

Rumpel 

Rommelaere 


Longest 
Duration 

(days) 


10 
12 
12 
18 
24 
47 


Name  of  Observer 


KoUe 

Donitz 

Abel  and  Clausen 

Pfeiffer 

Burgers 


Longest 
Duration 

(days) 


48 
49 
15 
13 


Several  different  methods  for  the  detection  of  cholera  carriers  are 
applicable.  All  of  them  are  based  upon  the  facility  with  which  the 
vibrio  grows  upon  Dunham's  solution.  Particles  of  feces  are  planted  in 
this  medium  and  subsequently  examined  for  comma-shaped  microorgan- 
isms. If  found,  the  diagnosis  is  presumptive.  Pure  cultures  should  then 
be  made  and  studied  for  agglutination.    See  page  114. 

The  routine  bacteriological  examination  of  immigrants  from  cholera- 
infected  ports,  as  practised  at  the  Quarantine  Station  at  New  York,  in 
1912,  was  as  follows :  ^ 

1.  Inoculation  of  feces  into  Dunham's  peptone  solution  (at  37°  C). 

2.  Subinoculation  at  the  end  of  six  hours  of  one  loop  of  the  surface 
growth  into  a  second  Dunham's  peptone  tube. 

3.  Examination  of  a  smear  taken  from  the  surface  growth  of  the 
second  Dunham's  peptone  tube,  after  incubation  6  to  9  hours  at  37°  C. 

Bendick  uses  a  modified  Dunham's  solution  containing  sodium  car- 
bonate, 1  gram;  saccharose,  5  grams;  and  phenolphthalein  solution,  5 
c.  c,  in  addition  to  the  usual  amount  of  water,  peptone  and  salt.  The 
cholera  vibrios  ferment  the  saccharose ;  the  acid  produced  unites  with  the 
sodium  carbonate  and  the  medium  becomes  neutral,  hence  the  red  color 
of  the  phenolphthalein  disappears. 

Immunity  and  Prophylactic  Inoculations. — The  immunity  produced 
by  an  attack  of  the  disease  is  of  short  duration.  Attempts  have  been 
made  to  produce  an  artificial  immunity  by  the  injection  of  cholera  cul- 
tures. These  were  first  made  by  Ferran  of  Spain  in  1884,  but  the  cultures 
used  by  him  obtained  directly  from  cholera  stools  were  not  pure.  Haff- 
kine  tested  the  method  on  a  large  scale  in  India ;  over  40,000  persons  were 
inoculated  with  attenuated  cultures  up  to  1895.     Haffkine  proceeded  in 

^Philippine  Journal.  Sc.  Sec.  B.,  Trop.  Med.,  1915,  X.  1. 
'  Hygienische  Rundschau,  February,  1910,  Vol.  XX,  No.  4. 
»  Bendick:     Jour,  of  Am.  Pub.  Health  Assn.,  I,  No.  12,  906,  Dec,  1911. 


CHOLEEA  119 

accordance  with  the  well-known  methods  of  Pasteur  in  anthrax,  by  using 
two  vaccines  of  different  strengths.  The  first  was  obtained  by  growing  the 
culture  at  a  heightened  temperature,  which  produced  a  very  attenuated 
strain.  The  second  contained  living  vibrios  altered  by  passage  through 
guinea-pigs.  The  reactions  produced  were  generally  slight  in  degree  and 
consisted  of  a  brief  elevation  in  temperature,  headache,  malaise,  as  well 
as  redness,  swelling,  and  pain  at  the  site  of  injection.  The  results  were 
not  clear  cut  on  account  of  the  difficulty  of  comparing  the  disease  in  the 
inoculated  with  suitable  controls.  However,  the  general  impression  is 
that  the  method  has  distinct  prophylactic  value.  This  opinion  has  been 
confirmed  by  the  later  work  in  various  parts  of  India,  where,  up  to  the 
year  1899,  of  5,778  inoculated  persons,  only  27  had  cholera  and  14  died, 
whereas,  of  5,519  non-inoculated,  198  had  cholera,  of  which  121  died. 
Kolle  showed  that  the  blood  serum  of  the  inoculated  persons  contains  a 
specific  bacteriolysin  similar  to  that  contained  in  the  blood  serum  of 
those  who  have  recovered  from  the  disease.  Kolle  uses  2  nig.  of  an  agar 
culture  suspended  in  1  c.  c.  of  physiological  salt  solution  and  killed  at 
58°  C.  for  one  hour  for  the  first  injection,  and  twice  this  dose  (1  mg.) 
for  the  second;  0.5  per  cent,  of  phenol  is  added  as  a  preservative.  The 
immunity  produced  by  these  protective  inoculations  lasts  a  long  time, 
but  after  a  year  the  specific  antibodies  begin  to  diminish  in  the  blood 
serum. 

There  seems  to  be  little  doubt  in  Japan  concerning  the  value  of  the 
protection  afforded  by  the  inoculation  of  dead  cultures,  for  in  the  district 
of  Hiogo,  during  the  epidemic  of  1902,  77,907  persons  were  inoculated. 
Of  these  47,  or  0.06  per  cent.,  took  cholera,  and  20,  or  0.02  per  cent., 
died,  whereas,  among  825,287  persons  not  inoculated,  1,152,  or  0.13  per 
cent.,  took  the  disease,  and  863,  or  0.1  per  cent.,  died.  It  is  especially 
noteworthy  that  all  the  cases  among  the  inoculated  group  were  in  those 
who  received  an  injection  of  2  mg.  of  the  dead  culture.  Later  i  mg.  were 
used,  and  in  this  group  no  cases  occurred. 

Protective  inoculations  as  a  prophylactic  measure  against  cholera  will 
never  be  popular  or  necessary  in  communities  with  sufficient  sanitation. 
It  is,  however,  of  value  in  camps,  armies  on  the  march,  for  physicians, 
nurses,  ward  tenders,  and  others  especially  exposed. 

Quarantine. — ^Cholera  is  an  infection  which  fully  justifies  maritime 
quarantine  practice.  The  disease  may  be  blocked  by  a  careful  system  of 
inspection,  detention,  and  disinfection  at  the  seaport.  In  order  for  mar- 
itime quarantine  to  be  effective  for  cholera,  it  must  have  the  assistance 
of  a  bacteriological  laboratory  to  diagnose  cases  and  recognize  carriers. 
A  strict  watch  must  be  kept  for  mild  and  ambulant  cases  of  the  disease. 

In  the  summer  of  1912  the  quarantine  authorities  at  the  large  sea- 
ports on  our  Atlantic  littoral  examined  about  34,000  specimens  of  bowel 
discharges  from  passengers  and  crew  from  cholera-infected  ports.     At  the 


120      DISEASES   SPKEAD   THKOUCJH   ALVINE    DISCHARf;ES 

New  York  quarantine  the  cholera  vibrio  was  isolated  from  28  persons  sick 
with  the  disease,  and  27  healthy  persons  were  found  to  be  discharging 
vibrios  in  their  feces.  These  carriers  could  jiot  have  been  discovered 
except  by  laboratory  examination.  Seven  cases  of  cholera  were  detected 
at  other  ports  by  the  same  methods.  There  can  be  no  doubt  that  the 
adoption  of  this  measure  kept  cholera  out  of  the  country. 

The  Foreign  Inspection  maintained  by  the  United  States  Government 
during  the  epidemic  of  1892-93  was  a  convincing  demonstration  of  the 
value  of  this  service  as  one  of  the  safeguards  against  cholera.  Officers  of 
the  Public  Health  Service  stationed  at  foreign  ports  supervised  the  water 
and  food  supply  of  the  departing  vessels,  inspected  the  crew  and  passen- 
gers as  to  their  health;  those  coming  from  infected  localities  were  de- 
tained under  observation  5  days  before  they  were  permitted  to  embark. 
On  practically  none  of  the  vessels  complying  with  these  requirements  did 
cholera  appear,  whereas  it  broke  out  comparatively  frequently  on  vessels 
which  did  not  comply  with  the  restrictions,  but  sailed  from  the  same 
ports  under  similar  conditions.  A  similar  experience  demonstrating  the 
value  of  a  sanitary  inspection  of  vessels  leaving  an  infected  port  was 
demonstrated  in  the  Philippines,  where,  since  the  American  occupation, 
cholera  has  been  kept  off  the  returning  transports  and  its  interisland 
spread  has  been  checked  by  a  sanitary  supervision  of  vessels  at  both  the 
ports  of  departure  and  arrival. 

Personal  prophylaxis  requires,  first  of  all,  scrupulous  cleanliness  on 
the  part  of  the  person  and  his  surroundings.  Those  who  handle  cholera 
patients,  their  dejecta,  or  infected  articles  must  carefully  disinfect  their 
hands  each  time,  and  should  under  no  circumstances  eat  or  drink  any- 
thing in  the  sick  room.  During  cholera  times  all  water  and  food  of  every 
description  should  be  boiled  or  thoroughly  cooked  just  before  it  is  par- 
taken of.  Great  care  must  be  exercised  that  the  water  or  food  does  not 
become  infected  after  it  has  been  boiled  or  cooked.  The  usual  measures 
should  be  taken  to  guard  against  flies  and  other  vermin.  With  strict 
attention  to  these  measures,  it  is  possible  to  avoid  the  infection.  In  addi- 
tion, however,  attention  to  general  hygiene  and  especially  to  the  character 
of  the  food  and  regularity  of  meals  should  be  given.  Slight  attacks  of 
indigestion  and  diarrhea  should  receive  prompt  medical  attention.  Those 
exposed  should  protect  themselves  with  cholera  inoculations. 

Summary — Prevention. — Preventive  measures  should  first  of  all  be 
focused  upon  the  cholera  cases  in  order  to  prevent  the  spread  of  the 
infection  at  the  bedside.     This  includes  early  and  controlled  diagnosis. 

Cholera  patients  should  be  cared  for  in  special  hospitals  where  all 
these  necessary  measures  may  be  carried  out  by  trained  assistants.  The 
infection  in  cholera  stools  may  be  destroyed  with  formalin  (10  per  cent.), 
carbolic  acid  (5  per  cent.),  milk  of  lime  (1  to  8),  or  chlorinated  lime  (3 
percent.).     (See  page  1171.) 


DYSENTEEY  121 

Persons  leaving  a  cholera  region  should  either  be  detained  in  quaran- 
tine for  5  days  or  be  watched  this  length  of  time  after  arrival  at  the 
place  of  destination.  This  may  be  accomplished  by  requiring  them  to 
report  twice  daily  to  the  sanitary  authorities.  Fecal  examinations  should 
be  made  to  detect  carriers.  It  is  unnecessary  to  disinfect  merchandise 
shipped  from  a  cholera  town. 

For  the  control  of  a  cholera  outbreak  it  is  important  to  require  that 
all  cases^  as  well  as  all  suspicious  cases,  be  reported.  A  bacteriological 
laboratory  is  necessary  to  confirm  the  diagnosis  and  arrangements  must 
at  once  be  made  to  isolate  the  cases  and  to  disinfect  the  dejecta,  the  body 
and  bed  linen,  and  other  materials.  Convalescents  are  not  released  until 
two  successive  examinations  at  5-day  intervals  show  the  absence  of  the 
cholera  vibrios. 

On  account  of  the  frail  character  of  the  vibrio  a  general  disinfection 
of  the  house  is  not  necessary  in  cholera.  The  room  itself  may  be  treated 
with  formaldehyd  or  the  surfaces  washed  down  with  a  bichlorid  solution 
Or  one  of  the  alkaline  coal-tar  creosotes.  The  water-closets  may  be  disin- 
fected with  formalin,  carbolic  acid,  milk  of  lime,  or  chlorinated  lime. 
Spoons,  cups,  saucers,  and  remnants  of  food  should  be  treated  as  in  the 
case  of  typhoid.  Otherwise  the  prevention  of  cholera  is  a  strict  counter- 
part of  that  of  typhoid. 

A  summary  of  the  preventive  measures  necessary  to  control  an  epi- 
demic of  cholera  are :  centralization  of  authority  in  one  person ;  estab- 
lishment of  a  system  of  securing  and  reporting  information ;  organization 
of  the  personnel  for  the  sanitary  work;  enactment  of  necessary  ordi- 
nances ;  house  to  house  inspection ;  safe  disposal  of  feces  of  entire  popu- 
lation ;  provision  for  a  safe  water  supply ;  supervisory  control  of  food  and 
drink ;  a  search  for,  and  control  of  carriers ;  isolation  and  care  of  patients 
in  special  hospitals;  separate  hospitals  or  wards  for  suspects;  a  labora- 
tory ;  detention  camps  or  barracks  for  those  desiring  to  leave  the  infected 
area;  disinfection,  etc.  For  further  discussion  concerning  the  control  of 
epidemics,  see  page  368. 

DYSENTERY 

Classification. — For  the  purpose  of  prevention  we  may  consider  all 
dysenteries  under  three  heads:  (1)  bacillary  dysentery,  (2)  amebic 
dysentery,  (3)  symptomatic  dysentery. 

Bacillary  dysentery  is  an  acute  infectious  disease  caused  by  the 
B.  dy s enter iae,  an  organism  that  closely  resembles  the  typhoid  bacillus  in 
cultural  respects.  It  differs  from  typhoid  in  that  it  has  limited  or  no 
motility.  More  fundamental  differences  are  found  in  its  biological  prop- 
erties, such  as  specific  agglutination  and  pathogenic  poAver.  There  are 
at  least  two  well  recognized  types  of  B.  dysenteriae.    One  corresponds  to 


132      DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

Ihe  original  organism  discovered  by  Shiga  in  ]8!)7  in  llie  Japanese  epi- 
demic, and  the  other  to  that  described  by  Flexncr  in  Manila.  The  Shiga 
bacillus  does  not  ferment  mannite,  while  the  Flexner  ferments  that 
"sugar"  with  the  production  of  acid.  Further,  the  two  organisms  differ 
in  their  properties  of  agglutination  toward  specific  sera.  A  very  strong 
endotoxin  may  he  extracted  from  the  Shiga  type  which,  when  injected 
intravenously  into  rabbits,  produces  a  fatal  intoxication  with  a  faithful 
reproduction  of  the  symptoms  and  lesions  of  bacillary  dysentery.  Kraus 
and  Dorr  and  also  Todd  have  found  that  the  Shiga  strain  produces  such 
a  soluble  toxin,  which  is  not  the  case  with  the  Flexner  strain. 

Amebic  dysentery  results  from  infection  with  the  Entameha  his- 
tolytica, now  known  as  Loschia  histolytica.  There  are  marked  differences 
between  the  amebic  and  the  bacillary  types  of  the  disease.  The  former 
is  a  chronic  infection  which  starts  insidiously,  is  characterized  by  relapses 
and  recurrences,  is  frequently  associated  with  sequelae,  such  as  liver 
abscesses,  and  occurs  sporadically  or  in  endemic  foci,  mainly  in  the 
tropics.  Epidemic  outbreaks  of  the  amebic  form  of  dysentery  are  not 
known.  Bacillary  dysentery,  on  the. other  hand,  is  an  acute  febrile  dis- 
ease, usually  self-limited,  with  marked  symptoms  of  toxemia,  sudden 
onset,  no  sequelae,  and  occurs  in  widespread  and  severe  epidemics.  The 
bacillary  disease  occurs  in  the  temperate  regions  as  well  as  in  the  tropics, 
and  is  almost  always  the  cause  of  dysentery  outbreaks  in  ships,  camps, 
jails,  etc.  The  lesions  of  the  two  diseases  also  differ  markedly.  In  amebic 
dysentery  the  ulcers  are  undermined,  whereas  in  the  bacillary  disease  the 
inflammation  is  diffuse  and  of  varying  grades  of  severity,  which  may 
reach  coagulation  necrosis  or  gangrene.  There  are  also  notable  differ- 
ences in  the  treatment;  for  example,  ipecac  or  its  alkaloid  emetin  is  of 
service  in  amebic  dysentery,  but  of  no  value  in  the  bacillary  form.  So 
far  as  prevention  is  concerned,  however,  both  diseases  may  be  regarded 
as  intestinal  infections  entering  by  the  mouth,  and  therefore  the  prophy- 
laxis corresponds  closely  to  that  of  typhoid  or  cholera. 

Under  symptomatic  dysentery  are  grouped  all  other  conditions  with 
dysenteric  symptoms  resulting  from  a  great  variety  of  causes. 

Mode  of  Transmission. — The  dysentery  bacillus  enters  the  body  by 
the  mouth  and  leaves  the  body  in  the  alvine  discharges.  So  far  as  known, 
the  dysentery  bacillus  does  not  penetrate  deeply  into  the  tissues,  and  is 
seldom  found  in  the  circulating  blood.  It  therefore  does  not  appear  in 
the  urine. 

The  infection  is  transferred  from  man  to  man  directly  or  indirectly 
in  precisely  the  same  ways  described  for  typhoid.  Undoubtedly  drinking 
water  frequently  contains  the  infection,  and  well  marked  water-borne 
epidemics  have  been  reported  in  recent  years,  particularly  in  Japan. 
Contacts,  food,  and  flies  also  play  an  important  role.  The  epidemiology 
of  bacillary  dysentery  is  about  the  same  as  that  of  typhoid.     It  is  largely 


DYSENTEEY  123 

a  summer  disease.  In  wars  it  used  to  cause  great  ravages;  as  in  the 
Crimean  war^  our  own  civil  war,  the  Franco-Prussian  war,  and  the  recent 
Eussian-Japanese  war.  Overcrowding,  lack  of  cleanliness,  and  other  un- 
hygienic conditions  favor  the  spread  of  bacillary  dysentery,  so  that  it  is 
sometimes  called  famine,  asylum,  ship,  or  jail  dysentery.  The  mortality 
varies  greatly,  from  6  or  7  to  26  or  30  per  cent.  Bacillus  carrying  in 
dysentery  occurs,  and  probably  plays  a  more  important  part  in  spreading 
the  disease  than  we  now  suspect.  As  a  rule,  the  bacilli  soon  disappear 
from  the  stools  in  the  light  cases,  but  Shiga  has  found  them  more  per- 
sistent in  some  instances,  von  Drigalski  reports  an  outbreak  in  Germany 
caused  by  a  returning  soldier.  Eecent  convalescents  are  particularly  apt 
to  spread  the  infection.  Much  of  the  summer  diarrheas  of  infants  is  true 
bacillary  dysentery. 

The  Entameba  histolytica  is  also  taken  in  by  the  mouth  and  passed 
by  the  bowels.  There  has  long  been  a  suspicion  that  the  ameba  exists  in 
its  free  living  state  in  water,  upon  vegetables  and  fruits,  and  other  moist 
surfaces.  However,  Walker  ^  believes  it  is  possible  to  distinguish  between 
pathogenic  and  non-pathogenic  amebas,  and  reports  that  the  ordinary 
water  ameba  found  in  the  Philippines  is  harmless  to  man.  This  is  said 
to  accord  largely  with  similar  experience  in  Panama  and  other  tropical 
countries,  and  is  of  far-reaching  importance  from  the  point  of  view  of 
prevention.  It  emphasizes  the  point  that  amebic  dysentery  is  an  infec- 
tion conveyed  by  contacts  rather  than  through  water.  The  danger  of 
transmission  centers  in  the  infected  individual. 

Resistance. — The  dysentery  bacillus  has  about  the  same  resistance  to 
germicides  and  other  unfavorable  conditions  as  the  general  class  of  spore- 
free  bacteria.  It  dies  in  about  8  to  10  days  when  dried.  It  may  live  for 
months  when  moist.  It  is  sensitive  to  acids.  Phenol,  0.5  per  cent.,  kills 
the  dysentery  bacillus  in  6  hours,  1  per  cent,  in  30  minutes,  3  per  cent,  in 
1  to  2  minutes.  Bichlorid  of  mercury,  1-1,000,  kills  it  at  once,  and  direct 
sunlight  in  about  one-half  an  hour.  I  have  found  certain  strains  of  the 
dysentery  bacilli  somewhat  more  resistant  to  heat  than  the  typhoid  bacil- 
lus. They  are  killed  with  certainty  at  58°  C.  for  one  hour,  or  at  60°  C. 
for  20  minutes.  The  dysentery  bacillus  resists  cold  and  may  live  for 
months  when  frozen. 

The  Entameha  histolytica  is  probably  less  resistant  to  heat  and  germi- 
cides than  the  B.  dysenteriae.  Our  knowledge  concerning  the  effects  of 
drying,  sunlight,  and  other  deleterious  influences  is  still  uncertain. 

Immumty. — The  susceptibility  to  dysentery  varies  greatly.  This  is 
doubtless  due  in  part  to  the  bacterial  flora  of  the  intestinal  tract  as  well 
as  the  conditions  of  the  intestinal  mucosa.  Symbiosis  or  antibiosis  must 
play  a  very  important  role  either  in  permitting  or  hindering  the  dysentery 

^  Annual  Report  of  the  Bureau  of  Health  for  the  Philippine  Islands  for  the 
fiscal  year  July  1,  1912,  to  June  30,  1913.    Manila,  1913,  p.  102. 


l-?4:      DTSEASKS    SlM.'i^AD    'I'll  IJOCfl  II    AL\'IXK    DTSCHAPtOES 

bacillus  to  grow  in  the  intestinal  tract.  There  is  still  a  question  whether 
a  true  immunity  is  acquired  by  one  attack  of  bacillary  dysentery.  This 
seems  probable,  although  it  is  not  unusual  for  a  person  to  have  two  or 
more  attacks  of  dysentery  in  one  season.  Kolle  looks  upon  this  as  an 
exacerbation  of  a  chronic  type  brought  on  by  errors  of  diet,  exposure,  etc. 
The  experiments  on  animals  indicate  that  dysentery  probably  belongs  to 
that  group  of  diseases  which  leave  a  certain  amount  of  protection  after 
one  attack.  A  definite  and  high  grade  of  immunity  can  be  produced 
experimentally  in  several  of  the  lower  animals.  Upon  this  question,  how- 
ever, we  need  light.  Horses  may  be  immunized  to  a  high  degree,  and 
their  sera  contain  a  certain  amount  of  antitoxin  and  other  antiljodies. 
This  serum  has  been  used  in  treatment,  but  has  no  particular  value 
as  a  preventive.  There  is  evidently  no  immunity  in  amebic  dysen- 
tery. 

Prophylaxis. — To  avoid  dysentery  the  two  essentials  are :  scrupulous 
cleanliness  and  the  boiling  of  all  water  and  cooking  of  all  food  that  passes 
the  mouth.  The  usual  precautions  against  flies  and  vermin,  and  care  as 
to  personal  hygiene,  especially  diet,  are  indicated. 

Bacillary  dysentery  is  a  common  disease  in  infants,  and  it  would  be 
a  wise  precaution  to  consider  all  cases  of  infantile  diarrhea  as  infectious 
and  to  take  precautions  accordingly. 

Eecent  researches  ^  have  shown  that  emetin,  one  of  the  alkaloids  of 
ipecac,  is  quite  as  specific  for  amebic  dysentery  as  quinin  is  for  malaria. 
Large  doses  of  ipecac  have  been  used  for  many  years  in  the  treatment  of 
dysentery,  particularly  by  English  practitioners  in  India.  The  difficulty 
has  been  in  inducing  patients  to  retain  a  sufficient  amount  of  the  drug  by 
the  mouth.  Pelletier,  in  1878,  described  an  alkaloid  in  ipecacuanha 
which  he  called  "emetin."  Eogers,  in  1907,  demonstrated"  that  this  alka- 
loid would  rapidly  cure  an  amebic  hepatitis  in  the  presuppurative  stage, 
and  thus  prevent  the  formation  of  amebic  liver  abscess.  Having  con- 
vinced himself  of  the  action  of  emetin  on  amebas  in  vitro,  Eoger  decided 
to  use  emetin  subcutaneously  in  June,  1913-.  He  reported  two  cases  of 
the  severe  amebic  dysentery,  and  one  case  of  acute  hepatitis,  which  were 
rapidly  cured  as  the  result  of  this  treatment.  It  is  now  clear  that  emetin 
when  so  administered  will  promptly  kill  the  motile  forms  of  the  ameba, 
but  has  no  effect  whatever  upon  the  encysted  forms,  therefore  while  it 
promptly  cures  the  disease  it  does  not  cure  or  prevent  ameba  carriers, 
nor  does  it  prevent  relapses,  but  cures  them  as  soon  as  they  occur.  The 
amount  of  emetin  injected  is  from  %  to  1  grain,  although  as  much  as  -4 
grains  of  emetin  hydrochlorid  has  been  given  at  a  single  dose  by  Allan. 
Eoger  reports  the  use  of  one  grain  intravenously  with  no  bad  results. 
Emetin  has  no  therapeutic  virtue  in  bacillary  dysentery. 

'  Vedder.   E.   P>.:      Origin   and  Present   Status   of  the  Emetin  Treatment   of 
Amehic  Dysentery.     ./.  A.  Af.  A.,  Feb.  14.   1914,  Vol.  LXTT,  No.  7,  p.  501. 


HOOKWOEM    DISEASE  125 

Ameba  carriers  may  possibly  be  reached  by  irrigations  of  quinin  or 
nitrate  of  silver. 

Walker  and  Sellards  ^  emphasize  the  point  that  it  is  possible  to  recog- 
nize the  specific  Entameha  histolytica  in  all  cases  of  amebic  dysentery  or 
amebic  dysentery  carriers.  They  consider  it  probable  that  the  motile 
forms  found  in  the  acute  stage  of  the  disease  have  little  to  do  with  its 
transmission,  which  they  believe  is  probably  due  to  the  ingestion  of  the 
more  resistant  encysted  forms  derived  from  carriers.  Prophylaxis,  there- 
fore, should  be  directed  toward:  (1)  the  identification  of  carriers  by  the 
systematic  examination  of  stools  of  all  persons  whose  history  or  occupa- 
tion would  fit  them  for  such  a  role;  (2)  the  sanitary  disposal  of  feces; 
(3)  treatment  of  carriers  controlled  by  stool  examinations,  and  (-i)  pre- 
cautionary examination  of  the  stools  of  all  persons  living  in  endemic 
regions  in  the  effort  to  recognize  the  organism  while  the  disease  is  still 
in  the  somewhat  prolonged  period  of  incubation. 

Dysentery  shovild  be  included  in  the  notifiable  diseases  and  laboratory 
aid  furnished  by  the  Board  of  Health  to  assist  diagnosis.  Cases  should 
be  isolated  in  the  same  sense  that  cases  of  typhoid  are  isolated  and  disin- 
fection practiced  at  the  bedside.  Outbreaks  in  institutions  should  always 
be  investigated  and  vigorous  measures  taken  to  check  further  spread  and 
to  prevent  recurrences.  In  all  respects  the  prevention  of  dysentery  is  a 
close  parallel  to  that  of  typhoid. 


HOOKWORM  DISEASE 

(Uncinariasis  or  Ancylostomiasis) 

Theoretically  the  prevention  of  hookworm  disease  is  comparatively 
simple,  for  here  we  have  an  infection  of  which  Ave  know  the  parasite  and 
its  life  history,  its  mode  of  exit  and  entrance  into  the  body,  and  we  possess 
a  satisfactory  cure  for  the  disease  within  reach  of  all.  Practically,  how- 
ever, we  have  ignorance,  apathy,  poverty,  and  uncleanliness  to  deal  with 
before  satisfactory  prevention,  much  less  eradication,  can  be  achieved.  It 
is  now  plain  that  hookworm  disease  presents  a  sanitary  problem  of  first 
magnitude,  not  alone  in  our  southland,  but  in  practically  all  tropical  and 
subtropical  countries.  Further,  there  is  a  large  economic  and  industrial 
aspect  to  this  question  in  medical  biology. 

Distribution. — Hookworm  disease  encircles  the  globe  in  the  tropical 
and  subtropical  climes;  it  diminishes  toward  the  temperate  regions.  It 
is  not  endemic  in  the  colder  latitudes,  except  in  mines,  especially  those 
of  Wales,  Germany,  Netherlands,  Belgium,  France,  and  Spain.  The 
infection  belts  the  earth  in  a  zone  about  66°  wide,  extending  from  par- 

*  Walker  and  Sellards:  Experimental  Entamebic  Dysentery.  Third  Biennial 
Conforoncc,  Far  Eastern  Association  of  Tropical  Medicine. 


126     DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

allel  3G  north  to  parallel  30  south  latitude.  The  amount  of  infection  is 
great  in  American  Samoa,  where  it  is  found  in  70  per  cent,  of  the  pop- 
ulation ;  in  the  southern  two-thirds  of  China,  in  75  per  cent,  of  the  pop- 
ulation ;  in  India  from  CO  to  80  per  cent,  of  the  300,000,000  population 
have  the  worms;  in  Ceylon,  90  per  cent,  in  many  parts;  in  Natal,  50  per 
cent,  of  the  coolies  on  sugar  and  tea  estates;  in  Egypt,  50  per  cent,  of 
the  laboring  class;  in  Dutch  Guiana,  90  per  cent,  in  many  parts;  in 
British  Guiana,  50  per  cent,  of  all;  in  Colombia,  90  per  cent,  of  those 
living  between  sea-level  and  3,000  feet,  which  includes  most  of  the  pop- 
ulation ;  in  1904  the  Porto  Rican  Anemia  Commission  found  that  90  per 
cent,  of  the  rural  population  of  that  island  were  infested.  Stiles  esti- 
mates that  in  this  country  2,000,000  individuals  have  the  parasites  from 
the  Potomac  to  the  Mississippi,  along  the  Atlantic  littoral  and  the  Gulf 
states.  In  some  German  mines  from  30  to  80  per  cent,  of  the  miners 
have  been  found  to  be  infested.  Gunn  ^  has  shown  that  from  50  to  80 
per  cent,  of  those  working  in  the  California  mines  harbored  hookworms 
in  1911.  It  is  probable  that  all  the  older  mines  employing  foreign  la- 
borers sooner  or  later  become  endemic  foci. 

In  1879  an  outbreak  of  hookworm  disease  occurred  among  the  labor- 
ers in  St.  Gothard's  tunnel  and  was  called  miner's  anemia.  This  aroused 
the  interest  of  the  scientific  world.  The  polluted  soil  of  the  tunnel  was 
found  to  be  impregnated  with  the  eggs  and  larvae.  Interest  in  the  dis- 
ease in  this  country  was  aroused  through  the  work  and  enthusiasm  of 
Stiles. 

Varieties  of  Hookworm. — Almost  all  mammalian  animals  have  hook- 
worms, but  each  host  species  has  a  different  kind  of  hookworm;  that  is, 
the  hookworms  of  the  dog,  fox,  horse,  the  seal,  etc.,  differ  from  each 
other,  and  are  specific.  The  hookworm  of  the  dog  will  not  infest  man 
or  other  mammalian  host;  the  hookworms  of  man  do  not  develop  to 
maturity  in  the  lower  animals. 

Two  species  of  hookworm  are  found  in  man — the  old  world  form 
(Ancylostoma  duodenale) ,  and  the  new  world  form  (Necator  ameri- 
canus).  The  distinction  between  these  two  worms  has  a  zoological  rather 
than  a  practical  bearing,  for  both  produce  the  same  symptoms,  require 
the  same  treatment,  have  the  same  life  history,  and  call  for  the  same 
preventive  measures.  The  chief  differences  between  these  two  hookworms 
consist  in  the  fact  that  the  old  world  form  has  one  pair  of  ventral  hooks, 
two  conical  dorsal  teeth,  and  the  posterior  ray  of  the  caudal  bursa  divides 
two-thirds  its  way  from  the  base,  and  each  division  has  three  tips  (tri- 
partite). The  new  world  form  has  ventral  lips,  a  dorsal  median  tooth, 
and  one  pair  of  dorsal  and  one  pair  of  ventral  lancets  deep  in  the  buccal 
capsule.  The  posterior  ray  of  the  caudal  bursa  divides  at  its  base  and 
each  division  has  two  tips  (bipartite). 

^Jour.  A.  M.  A.,  Vol.  LVI,  No.  4,  Jan.  28,  1911,  p.  259. 


HOOKWORM    DISEASE 


127 


Fig.  15. — Hook- 
worms, Natural 
Size. 


According  to  Stiles,  the  vast  majority  of  cases  of  hookworm  disease 
in  man  in  the  United  States  are  due  to  the  new  world  form  {Necator 
americanus) . 

Modes  of  Transmission. — The  usual  mode  of  trans- 
mission, perhaps  in  90  per  cent,  or  more  of  the  cases, 
is  through  the  skin.  The  embryos  may  also  be  taken 
by  the  mouth  in  drinking  water  or  solid  food,  or  from 
contaminated  objects,  such  as  dirty  fingers.  It  has 
been  shown  by  experiment  that  animals  can  be  in- 
fected by  drinking  water  containing  the  embryos.  While  this  source  of 
infection  plays  a  minor  role,  it  is  not  to  be  disregarded. 

The  infection  leaves  the  body  exclusively  in  the  feces, 
which  contain  the  eggs  of  the  parasite. 

The  Parasite.' — For  a  correct  understanding  of  the  pre- 
vention of  hookworm  disease  it  is  necessary  to  have  a  knowl- 
edge of  the  essential  features  of  the  life  history  of  the 
parasite. 

Hookworms  are  round  worms  (nematodes)  belonging  to 
the  sub-family  Uncinariinae.  The  adult  worm  is  about  one- 
half  to  three-quarters  of  an  inch  long,  and  about  the  diameter 
of  a  wire  hairpin. 

The  adult  hookworm  lives  in  the  intestinal  tract,  usually 
in  the  small  intestine.  It  attaches  itself  to  the  intestinal 
wall,  wounds  the  mucosa,  sucks  blood,  eats  the  epithelium, 
and  probably  produces  a  toxic  substance  which  injures  the 
host. 

The  female  worm  lays  a  prodigious  number  of  eggs  in  a 
never-ending  stream,  which  pass  from  the  host  in  the  feces. 
The  embryo  does  not  mature  within  the  egg  except  in  the 
presence  of  oxygen.     Hookworm  embryos,  therefore,  do  not 
undergo   full   development  until  the   eggs   are 
discharged  into  the  outer  world.     On  the  other 
hand,  the  eggs  of  Strong yloides  stercoralis,  the 
parasite    of    Cochin-China    diarrhea,    contain 
fully  developed  embryos  in  the  freshly  passed 
feces.     The  hookworm  embryos  become  mature 
'within  the  egg  in  6  to  8  hours  in  the  presence 
of  moisture,  warmth,  and  oxygen.     It  is,  there- 
fore, necessary  to  examine  the  fresh  stools  in 
order  that  this  difference  between  the  two  infec- 
tions may  be  of  value  in  differential  diagnosis. 
Under  favorable  conditions  the  embryo  escapes  from  the  egg  and 
becomes  a  larva  in  about  24  hours.     This  free-living  larva  exists  and 


Fig.  16.- 


-HooKWORM   Em- 
bryo. 


UA    T)iSKy\siw  siM.'KAi)  'riTKOTTrar  ALViXK  i)isc;irAi{riii:s 

moves  in  moist  soil  niid  Feeds  upon  the  or^aiiie  niiiiier  foiuid  tliere.  In 
the  course  of  two  days  or  more  tlie  larva  sheds  its  skin  (ecdysis)  and  thus 
passes  to  the  first  molt.  TIk!  larva  continues  as  a  free-livin<^  j)arasit(?, 
aiul  ill  ahoiii  a,  week  a,i!,ain  sheds  ils  skin,  hut  now  eontiniies  to  livi;  en- 
cysted inside  this  discarded  skin.  This  is  the  second  ecdysis  and  this 
encysted  larva  no  longer  takes  food.  This  stage  in  the  life  history  of  the 
parasite  is  of  special  importance  for  the  reason  that  it  is  capable  of 
piercing  the  skin ;  that  is,  it  is  the  infecting  stage.  In  this  condition  the 
parasite  may  continue  its  free  living  existence  in  a  dormant  condition  for 
five  months,  p'erhaps  longer.  The  larva  has  a  slow  motion  and  under 
favorable  conditions  probably  travels  a  number  of  yards,  increasing  the 
radius  of  soil  pollution. 

The  hookworm  larva  passes  in  all  through  five  ecdyses  or  molts.  Two 
of  them  occur  during  its  free-living  stage  and  three  of  them  during  its 
residence  in  the  host.  With  each  ecdysis  the  larva  approaches  more  nearly 
the  appearance  and  structure  of  the  adult  worm. 

The  larva  pierces  the  skin  and  passes  by  a  circuitous  route  to  the 
intestinal  tract.  The  parasite  may  enter  the  skin  at  any  place,  but  it 
usually  goes  through  the  soft  and  thin  skin  between  the  toes.  In  its 
passage  through  the  skin  the  larva  produces  an  inflammatory  reaction 
(ground-itch)  which  results  partly  from  the  irritating  action  of  the  pres- 
ence of  the  foreign  body,  but  mainly  from  the  bacteria  carried  along  with 
the  larva.  These  primary  lesions  may  consist  of  a  few  itching  papules 
or  pustules  to  a  severe  dermatitis.  Of  4,741  patients  questioned  by 
Ashford,  King,  and  Gutierrez  in  Porto  Eico,  4,664,  or  about  98  per  cent., 
gave  a  history  of  ground-itch,  which  is  now  recognized  as  the  first  stage 
of  the  disease. 

The  fact  that  the  infection  with  hookworm  disease  is  usually  con- 
tracted through  the  skin  was  discovered  by  Looss  in  Cairo,  Egypt.  He 
also  nnraveled  the  course  of  the  parasite  from  the  skin  to  the  intestines. 
This  brilliant  discovery,  which  is  one  of  the  romances  of  medical  biology, 
is  the  foundation  upon  which  prevention  against  the  infection  depends. 
In  1895  Looss  accidentally  spilled  a  drop  of-  water  containing  many 
encysted  larvae  upon  his  hand,  and  noted  that  they  disappeared,  leaving 
their  delicate  sheaths  behind  them.  Seventy-one  days  subsequently  he 
developed  intestinal  uncinariasis.  The  experiment  was  then  repeated 
upon  a  volunteer,  and  hookworm  eggs  appeared  in  his  stools  in  74  days. 
Claude  Smith  found  eggs  in  the  feces  6^/^  weeks  and  7  weeks  after  experi- 
mental skin  infection  on  two  persons  with  the  American  parasite  (Neca- 
tor  americanus) . 

The  wanderings  of  the  parasite  from  the  skin  to  the  intestine  were 
worked  out  by  Looss  partly  by  placing  larvae  upon  an  amputated  leg  and 
also  by  studying  the  question  upon  puppies.  The  hookworm  larva  usually 
pierces  the  skin  through  a  hair  follicle,  enters  the  subcutaneous  tissue. 


HOOKWORM    DISEASE  129 

and  then  finds  its  way  through  the  lymphatics  to  the  neighboring  lymph 
nodes.  The  larvae  are  able  to  squirm  through  the  lymph  nodes,  pass  to 
the  thoracic  duct,  and  thence  to  the  vena  cava  and  the  right  heart. 
From  the  right  heart  they  are  carried  in  the  blood  stream  to  the  lungs. 
The  larvae  are  too  large  to  pass  the  capillaries  of  the  lungs.  They  pierce 
the  capillary  walls  and  appear  in  the  alveoli  and  are  now,  to  all  intents 
and  purposes,  again  in  the'  outer  world.  They  pass  up  the  bronchi  and 
trachea  to  the  throat,  whence  they  are  swallowed,  and  finally  lodge  in  the 
small  intestines.  During  their  travel  through  the  body  they  pass  through 
three  ecdyses. 

The  adult  worm  attaches  itself  to  the  mucous  membrane  by  means  of 
the  powerful  buccal  lancet.  The  epithelium  is  drawn  into  the  buccal 
cavity  as  though  by  a  powerful  suction.  The  worms  are  usually  found  in 
the  small  intestine,  especially  in  the  Jejunum,  less  often  in  the  duodenum, 
and  rarely  in  the  ileum  and  lower  reaches  of  the  intestinal  tract;  they 
are  occasionally  met  with  in  the  stomach. 

The  parasites  imbibe  large  amounts  of  blood,  some  of  which  passes 
through  the'  worm  unaltered.  The  wound  continues  to  bleed  after  the 
worm  releases  its  hold,  owing  perhaps  to  a  hemolytic  substance  in  the 
mouth  parts  of  the  parasite.  The  worm  does  not  remain  fastened  to  one 
place  indefinitely,  but  releases  its  hold  and  attaches  itself  anew.  This 
produces  numerous  minute  wounds,  favoring  secondary  infections.  The 
hookworm  probably  produces  a  poison  which  is  absorbed  and  which  ac- 
counts, in  part,  for  the  anemia  and  other  symptoms  of  the  disease.  The 
severity  of  the  symptoms  bears  no  definite  relation  to  the  number  of 
worms.  The  number  varies  greatly  in  individual  cases ;  from  one  or  two 
to  thousands.  Sandwith  counted  250  worms  and  575  bites  in  one  case ; 
2,000  worms  are  not  an  uncommon  number.  The  Porto  Eican  Anemia 
Commission  counted  as  many  as  4,600  passed  by  one  individual. 

Immunity. — There  is  no  acquired  immunity  to  this  disease.  There 
is,  however,  a  definite  racial  immunity,  as  shown  by  the  negroes  and  the 
Filipinos,  who  are  often  infested  but  have  comparatively  slight  symptoms. 
Stiles  found  that  in  this  country  the  negro  is  the  great  reservoir  for 
hookworm  disease  in  that  he  is  frequently  infected  but  slightly  affected. 
Perhaps  the  negro  has  had  the  disease  so  many  generations  in  Africa  that 
he  has  become  immune.  It  is  conjectured  that  the  infection  was  brought 
to  America  through  the  negro  slave  trade.  Hookworm  disease  lowers 
resistance  and  greatly  increases  the  chances  of  other  infections,  especially 
tuberculosis.  The  secondary  results  are  often  more  disastrous  than  the 
primary  effects. 

Resistance  of  the  Parasite. — The  adult  worm  in  the  intestinal  tract 
may  be  benumbed  or  killed  with  thymol,  betanaphthol,  chloroform,  gaso- 
line, eucalyptus  oil,  and  other  vermifuges. 

From  the  standpoint  of  prevention,  it  is  more  important  to  know  the 
6 


130      DISEASES   SPREAD   THROUGH   ALVINE   DISCHARGES 

resistance  of  the  eggs  and  larvae  during  their  free-living  stages.  Stiles 
and  Gardner  have  shown  that  the  soil  under  and  around  privies  is  not 
entirely  free  from  infection  with  hookworm  even  five  months  after  the 
privy  was  last  used,  although  the  infection  is  considerably  reduced  at  the 
end  of  four  months.  When  the  fecal  matter  has  undergone  decomposition 
under  water  most  of  the  hookworm  eggs  are  dead  in  about  ten  weeks, 
though  some  still  survive,  but  probably  all  are  dead  in  three  months.  It 
would  not  be  safe  to  use  such  material  as  a  fertilizer  in  less  than  three 
months.  The  larvae  may  live  in  water  at  least  thirty  days.  The  encysted 
stage  is  most  resistant,  surviving  five  months ;  perhaps  longer. 

The  larvae  are  readily  killed  by  dryness  and  freezing.  The  infection 
was  once  considered  to  be  dust-borne,  but  the  fact  that  the  parasites  are 
killed  by  drying  renders  the  danger  from  dust  negligible.  The  fact  that 
freezing  kills  the  larvae  largely  explains  why  the  disease  is  not  endemic 
in  this  country  north  of  the  Potomac. 

It  has  been  shown  that  chlorinated  lime  fails  to  kill  hookworm  eggs 
in  23  to  40  hours.  Schiiffler  kept  the  larvae  alive  almost  four  months  in 
water  with  two  or  three  drops  of  a  one  per  cent,  quinin  solution  to  10  c.  c. 
Oliver  found  that  sea  water  killed  the  larvae  in  37  minutes. 

Prevention,. — The  prevention  of  hookworm  disease  consists  in  prevent- 
ing pollution  of  the  soil  and  in  treating  existing  cases  so  as  to  diminish 
the  amount  of  infection.  The  principles  of  prevention  are  easy  in  theory, 
but  their  application  is  difficult  in  practice  on  account  of  the  widespread 
and  enormous  amount  of  the  disease.  The  suppression  of  hookworm 
disease  means  the  social  and  economic  uplift  of  nations,  the  education 
of  millions  of  people,  and  an  entire  change  in  their  daily  hygienic  habits. 
Education  of  the  masses  is  an  important  factor,  calling  for  cooperation 
between  the  health  authorities,  civic  forces,  the  medical  profession, 
schools,  and  philanthropic  agencies ;  it  is  something  for  the  preacher  and 
teacher. 

Soil  Pollution. — The  prevention  of  soil  pollution  is  the  essential 
factor;  it  is  the  key  to  the  situation.  This  one  line  of  prevention  would 
blot  hookworm  disease  out  of  existence.  This  requires  the  building  of 
proper  privies,  and  insisting  upon  their  being  used  in  country  districts. 
In  warm  countries  direct  pollution  of  the  soil  is  much  more  common  and 
also  much  more  dangerous  than  in  cold  countries.  Add  to  this  the  cus- 
tom of  going  barefooted  and  we  have  all  the  factors  necessary  for  the 
dissemination  of  hookworm  infection. 

Stiles  estimates  that  68  per  cent,  of  the  rural  homes  in  the  South  are 
without  privies.  Even  many  schools  do  not  have  these  accommodations, 
and  are,  therefore,  hotbeds  of  infection.  For  the  care  and  disposal  of 
night  soil  see  chapter  on  sewage. 

The  Eradication  of  the  Infection  in  Man. — Hookworms  may  be 
expelled  from  the  intestinal  tract  by  the  use  of  thymol,  betanaphthol   or 


HOOKWOEM    DISEASE  131 

other  anthelmintic.  The  eradication  of  the  infection  through  the  treat- 
ment of  all  infected  persons  is  an  essential  factor  in  preventive  measures. 
The  usual  treatment  is  as  follows :  Saturday  evening  a  full  dose  of  mag- 
nesium sulphate  is  given  to  permit  direct  access  of  the  thymol  to  the 
worms,  which  are  often  imbedded  in  the  mucus  or  chyme.  The  object  is 
to  treat  the  parasite  and  not  the  host.  On  Sunday  morning,  at  8  o'clock, 
2  grams  (30  grains)  of  thymol,  for  an  adult,  finely  powdered  in  capsules, 
are  given  by  the  mouth.  TWo  hours  later,  at  10  o'clock,  2  more  grams  are 
administered ;  and  at  12  o'clock  another  dose  of  salts.  During  the  treat- 
ment it  is  important  to  avoid  alcohol,  fats,  and  oils,  as  thymol  is  soluble 
in  these  substances  and  may,  therefore,  be  dangerous,  as  they  favor 
absorption.  The  treatment  is  repeated  every  Sunday  until  the  eggs  dis- 
appear. Usually  two  or  more  treatments  are  necessary.  Eoughly  speak- 
ing, about  one-half  of  the  cases  clear  up  in  three  treatments;  90  per  cent, 
in  five  treatments,  and  it  is  necessary  to  administer  drugs  to  the  other 
10  per  cent,  anywhere  from  6  to  20  times,  according  to  the  case.  A 
microscopic  examination  of  the  feces  for  eggs  will  determine  when  the 
treatment  has  been  effective. 

The  eradication  of  the  infection  in  man  was  carried  out  on  a  whole- 
sale scale  by  the  Porto  Eican  Anemia  Commission,  consisting  of  Ashford, 
King,  and  Gutierrez.  Their  methods  were  highly  successful  and  will 
doubtless  serve  an  equally  useful  purpose  in  other  places.  They  estab- 
lished a  clinic  for  the  microscopic  diagnosis  and  free  treatment  of  the 
disease.  The  good  results  of  treatment  spread  rapidly,  so  that  the  facil- 
ities of  the  clinic  were  soon  taxed  to  its  utmost  capacity.  Not  the  least 
important  function  of  the  clinic  was  to  educate  the  profession  as  well  as 
the  people.  In  a  little  while  the  clinic  was  moved  to  another  point,  and 
so  on,  until  it  gradually  covered  the  entire  island. 

Education. — Education  is  one  of  the  most  important  factors  in  erad- 
icating hookworm  disease,  for  the  reason  that  its  final  control  depends 
upon  improvements  in  the  sanitary  habits  of  the  people,  especially  in  the 
rural  districts.  To  change  the  daily  habits  of  half  a  nation  is  an  uplift 
that  requires  time  and  patience.  It  is  perhaps  best  to  begin  with  the 
school  children;  even  then  it  will  take  a  generation  for  results.  Very 
little  can  be  accomplished  by  force,  and,  if  the  customs  and  prejudices  of 
the  people  are  ignored,  the  reformer  and  benefactor  meet  with  rebuff  and 
failure.  It  is  a  good  idea  to  have  a  public  health  day  or  a  public  health 
week  in  the  schools,  during  which  time  lectures  and  educational  work 
upon  hookworm,  typhoid,  tuberculosis,  and  other  prevalent  infections  are 
considered.  The  children  carry  the  lesson  into  the  home.  Pamphlets, 
posters,  lectures,  exhibits,  and  popular  articles  in  the  magazines  and 
newspapers  all  contribute  their  share.  The  medical  profession  in  the 
infected  areas  may  need  instruction  and  a  little  prodding  to  awaken 
interest  in  the  problem.     In  the  popular  education  on  health  matters 


132      DISEASES   SPllEAD   THROUGH   ALVJNE   DISCHARGES 

the  medical  profession  sliould  lead,  especially  tlirougli  the  health  au- 
thorities. This  has  also  become  one  of  the  manil'est  duties  of  the  prac- 
titioner. 

Cleanliness. — After  all,  the  prevention  of  hookworm  disease  is  a 
question  of  decency  and  cleanliness.  Water  sometimes  carries  the  infec- 
tion, hence  it  should  be  clean  or  cleansed  by  filtration  or  boiling.  Soiled 
hands  may  carry  the  infection  to  the  mouth,  hence  they  should  be  washed 
before  eating.  Vegetables  fertilized  with  night  soil  may  be  infected. 
This  practice  is  not  clean  and  should  be  forbidden,  especially  in  the  case 
of  those  vegetables  usually  eaten  raw.  With  cleanly  habits  there  would 
be  no  soil  pollution,  and  the  disease  would  be  checked. 

Personal  Prophylaxis. — Personal  prophylaxis  consists  in  wearing 
shoes  and  otherwise  avoiding  contact  with  the  infected  soil.  Brick  mak- 
ers, miners,  and  others  compelled  to  work  in  infected  soil  should  wear 
gloves.  Other  measures,  such  as  boiling  the  water,  eating  only  cooked 
or  clean  food,  washing  the  hands,  and  avoiding  the  infected  area, 
have  either  been  dwelt  upon  or  are  too  obvious  to  need  further  em- 
phasis. 

Immigration. — An  important  factor  in  the  spread  of  hookworm  dis- 
ease in  the  United  States  is  immigration.  Every  country  that  brings 
laborers  from  hookworm  regions  is  bringing  in  a  constant  stream  of 
infection.  California  has  established  quarantine  measures  against  Indian 
coolies,  90  per  cent,  of  whom  are  infected. 

Collateral  Benefits. — The  best  part  of  a  hookworm  campaign  is  the 
collateral  good  it  does.  This  applies  as  well  to  a  sanitary  campaign 
directed  against  almost  any  disease.  The  suppression  of  hookworm  dis- 
ease will  diminish  the  amount  of  tuberculosis,  typhoid  fever,  dysentery, 
and  other  infections.  Thus,  in  Bilibid  prison,  Manila,  the  death  rate  was 
formerly  excessive — 234  per  thousand  when  the  Americans  took  charge. 
This  was  reduced  to  75  per  thousand  by  sanitary  measures,  such  as  boiled 
water,  screens,  disinfection,  improved  food,  less  crowding,  better  air,  more 
sunlight,  etc.,  but  despite  these  sanitary  improvements  the  death  rate 
could  not  be  hammered  down  below  75  per  thousand.  Then  it  was  found 
that  many  of  the  prisoners  were  infected  with  hookworms.  Thymol  was 
administered  and  the  death  rate  fell  to  13.5  per  thousand.  Another 
instance  of  the  collateral  benefits  resulting  from  sanitary  work  is  the 
plague  campaign  in  San  Francisco,  which  cut  typhoid  fever  in  half, 
although  no  special  attention  whatever  was  paid  to  the  latter  disease. 
The  purification  of  the  water  supply  in  Hamburg  by  filtration  cut  down 
the  general  death  rate  and  diminished  the  morbidity  of  diseases  not 
water-borne.  One  of  the  most  encouraging  phases  of  sanitary  work 
directed  against  tuberculosis,  typhoid  fever,  and  hookworm  disease  is  the 
assurance  that  a  successful  campaign  will  result  in  fundamental  and 
permanent  control  or  eradication  of  other  communicable  diseases.     The 


HOOKWORM    DISEASE  133 

preveutioii  oi:  tuberculosis  deals  especially  with  personal  hygiene,  aud  the 
prevention  of  typhoid  fever  and  hookworm  with  the  sanitation  of  the 
environment.  The  combination  of  the  two,  therefore,  embraces  almost 
the  entire  range  of  preventive  medicine. 


CHAPTER  ITI 

DISEASES  SPEEAD  LARGELY  THROUGH  DISCHARGES  EROM 
THE  MOUTH  AND  NOSE 

TUBERCULOSIS 

Tuberculosis  is  the  most  frequent  and  widespread  of  ail  the  major 
infectious.  In  this  country  9  per  cent,  of  all  deaths,  and  in  Germany  12 
per  cent.,  are  caused  by  tuberculosis.  The  toll  falls  heaviest  during  the 
period  of  life  of  greatest  usefulness — thus  30  per  cent,  of  all  deaths 
between  the  years  of  15  and  60  are  due  to  pulmonary  tuberculosis  alone. 
Naegeli,  from  a  careful  examination  of  a  large  number  of  bodies  in 
Zurich,  found  evidence  of  tuberculosis  in  over  90  per  cent.  The  lowest 
figures  based  on  the  evidence  of  pathologic  anatomy  are  those  of  Bitzke, 
who  examined  1,100  bodies  in  Berlin.  In  children  under  15  he  found 
evidence  in  27.3  per  cent.,  and  in  persons  over  15,  58.2  per  cent.  The 
difi^erence  between  Naegeli's  figures  and  Bitzke's  is  due  to  a  difference  in 
the  interpretation  of  the  pulmonary  scars  and  adhesions  at  the  apices, 
and  the  small  fibrous  nodules  in  the  lungs.  Bitzke  does  not  consider  such 
lesions  as  of  tuberculous  origin,  and  leaves  them  out  of  his  figures.  If 
these  were  included,  his  percentage  would  also  be  very  much  higher.  The 
frequency  with  which  we  become  tuberculized  is  indicated  by  the  fact  that 
practically  all  persons  more  than  a  few  years  old  give  the  von  Pirquet 
cutaneous  reaction. 

In  the  United  States  it  is  estimated  that  160,000  persons  die  each 
year  of  tuberculosis.  Of  the  90,000,000  people  now  living  in  this  country, 
it  is  estimated  that  8,000,000  are  doomed  to  die  of  tuberculosis,  unless 
the  disease  is  checked.  The  loss  in  life  and  treasure  is  appalling.  It  is, 
therefore,  most  encouraging  that  preventive  measures  based  upon  modern 
conceptions  of  the  disease  as  a  communicable  infection  are  giving  encour- 
aging results. 

The  number  of  cases  of  clinical  tuberculosis  in  a  community  may  be 
estimated  according  to  Philip  of  Edinburgh,  by  multiplying  the  number 
of  deaths  from  tuberculosis  at  a  given  time  by  20.  More  conservative 
estimates  in  this  country  use  10  as  a  factor.  Thus  in  1911  there  were 
4,817  deaths  from  tuberculosis  in  Massachusetts,  which  would  mean 
nearly  50,000  cases  in  the  state  during  that  year.     About  1/5  of  these 

134 


TUBEECULOSIS  135 

are  extrapulmonary,  and  about  1/5,  or  10,000,  need  hospital  or  sani- 
tarium care.  Therefore,  the  number  of  deaths  from  tuberculosis  multi- 
plied by  2  give  an  approximate  estimate  of  the  number  of  beds  necessary 
to  provide  for  tlie  open  cases. 

Tuberculosis  began  to  decline  before  the  nature  of  the  infection  was 
known. ^  The  decline  is  gradual.  Modern  methods  have  so  far  made 
little  apparent  impression  upon  the  gross  amount  of  the  infection.  The 
social  and  economic  conditions  of  the  mass  of  the  population  must  be 
improved  before  any  great  decline  in  the  mortality  rate  can  be  expected, 
as  will  presently  be  pointed  out. 

Tuberculosis  is  fast  becoming,  in  fact  already  is,  a  class  disease ;  it  is 
more  prevalent  among  the  poor  than  the  well-to-do.  Hence  the  preven- 
tion of  tuberculosis  has  become  a  sociological  problem.  Poverty  with  all 
its  attendant  hardships,  such  as  poor  food,  bad  housing,  overwork,  and 
worry,  diminishes  resistance  to  the  infection;  while  prosperity,  which 
buys  good  food,  rest,  change  of  air  and  scene,  choice  of  occupation,  and 
diversion,  increases  our  resistance  to  the  infection,  and  avoids  contact 
with  it.  An  increase  of  wage  or  decrease  in  the  cost  of  living ;  shortening 
the  hours  of  work ;  improving  the  conditions  of  industrial  hygiene ; 
adding  to  the  number  of  holidays ;  playgrounds,  parks,  and  wholesome 
recreation,  all  help  to  increase  our  resistance  against  and  diminish  the 
prevalence  of  tuberculosis.  Science  has  shown  the  way;  it  remains  for 
society  to  apply  the  knowledge. 

The  Difference  Between  the  Human  and  the  Bovine  Tubercle  Bacilli. 
— There  are  at  least  four  kinds  of  tubercle  bacilli :  human,  bovine,  avian 
and  fish.  The  human  and  bovine  varieties  resemble  each  other  closely; 
the  essential  difference  lies  in  the  fact  that  the  human  type  is  very 
pathogenic  for  man,  but  has  little  pathogenicity  for  cattle,  rabbits,  mon- 
keys, and  other  animals.  On  the  other  hand,  the  bovine  type  is  very 
pathogenic  for  almost  all  mammalian  animals  except  man;  it  is  patho- 
genic for  man,  but  less  so  than  the  human  bacillus.  Even  when  large 
numbers  of  the  human  bacilli  are  injected  into  a  calf,  a  general  disease 
does  not  usually  result;  at  most  only  a  local  lesion  is  produced.  The 
critical  test  used  in  almost  all  laboratories  is  upon  rabbits.  When  0.01 
milligram  of  a  bovine  culture  is  injected  intravenously,  or  10  milligrams 
subcutaneously,  into  a  full-grown  rabbit,  generalized  tuberculosis  results 
in  about  6  weeks;  whereas  10  to  100  times  these  amounts  of  a  human 
strain  produces  at  most  a  slight  localized  tuberculosis.  The  culture  must 
be  young,  that  is,  about  3  weeks  old ;  it  should  be  taken  from  solid  media 
and  weighed  while  moist. 

The  human  bacillus  grows  more  luxuriantly  upon  culture  media, 
covering  the  entire  surface  of  the  medium  with  a  rich,  dry,  crinkled, 

^Villamin  in  1863  demonstrated  tliat  tuberculosis  is  a  contagious  disease; 
proven  hj  Koch  in  1882. 


136      DISEASES    SPREAD   THROUGH   MOUTH   AND   NOSE 

mold-like  vegetation.  The  growth  of  the  bovine  bacillus  upon  artificial 
culture  media  is  more  sparse,  thinner,  less  extensive,  and  somewhat 
slower.  According  to  Theobald  Smith,  who  first  pointed  out  the  differ- 
ences between  these  two  types,  the  human  bacillus  produces  in  artificial 
culture  media  a  different  reaction  curve  than  that  produced  by  the  bovine 
bacillus. 

Morphologically  the  bovine  bacillus  is  often  shorter,  plumper,  and 
stains  more  uniformly  than  the  human  bacillus,  which  is  ordinarily  club- 
shaped,  irregular,  and  stains  with  interrupted  markings.  The  morpho- 
logical and  tinctorial  characters  are  not  sufficiently  distinctive  to  dis- 
tinguish one  type  from  the  other. 

It  is  doubtful  whether  there  are  any  specific  differences  between  the 
tuberculins  of  bovine  and  human  origin. 

The  avian  tubercle  hacillus  is  found  most  frequently  in  chickens  and 
also  in  pigeons,  pheasants,  and  guinea-fowl.  Geese  and  ducks  appear 
immune.  The  avian  bacillus  is  quite  pleomorphic  and  stains  somewhat 
more  readily  than  either  the  human  or  bovine  types.  The  avian  bacillus 
grows  luxuriantly  upon  artificial  culture  media  at  45°  C.  and  even  multi- 
plies at  temperatures  as  high  as  50°  C,  which  is  in  marked  contrast  to 
the  mammalian  types,  which  do  not  vegetate  above  40°  C.  The  avian 
bacillus  grows  rapidly,  so  that  upon  glycerin-agar  or  upon  blood  serum 
there  is  an  abundant  growth  in  10  days,  which  consists  of  a  white,  moist, 
and  fatty  mass  quite  different  in  young  cultures  from  the  dried  and 
crinkled  appearance  of  the  human  type.  Guinea-pigs  show  a  decided 
resistance  to  the  avian  cultures,  but  rabbits  are  susceptible.  Chickens 
and  pigeons  may  be  infected  with  certainty  by  feeding,  and  it  is  probable 
that  in  nature  avian  tuberculosis  is  generally  transmitted  in  this  way. 

Fish  tuberculosis  shows  a  marked  difference  to  the  races  found  in 
warm-blooded  animals.  The  bacillus  grows  between  13°  and  36°  C,  the 
optimum  temperature  being  25°  C.  It  was  first  found  in  a  carp  and  is 
pathogenic  for  frogs.  Neither  the  avian  nor  the  fish  tubercle  bacilli  are 
pathogenic  for  man. 

Bovine  Tuberculosis  in  Man. — Concerning  bovine  tuberculosis  in  man 
we  now  possess  definite  knowledge  which  permits  of  precise  statements. 
At  one  time  the  danger  of  bovine  tuberculosis  to  man  was  greatly  exag- 
gerated. Koch  went  too  far  on  the  other  side  when  he  announced  at 
London  before  the  International  Congress  on  Tuberculosis  in  1901  that 
there  was  practically  no  danger  of  man  contracting  tuberculosis  from 
cattle.  In  recent  years  Koch  modified  this  dictum,  for  it  was  soon  proven 
that  the  bovine  bacillus  has  a  certain  amount  of  pathogenic  power  for 
man  and  that  some  of  the  tuberculosis  in  man  is  contracted  from  bovine 
sources.  It  is  now  estimated  that  perhaps  7  per  cent,  of  all  tuberculosis 
in  man  is  of  l)ovine  origin. 

Pulmonary  tul)ercu]osis  in  man  is  practically  never  associated  with 


TUBEECULOSIS 


137 


the  bovine  bacillus.  Bovine  tuberculosis  in  man  is  usually  a  disease  of 
the  lymph  glands  or  bones — the  lymph  nodes  of  the  cervical  region  and 
the  lymph  nodes  in  the  abdomen  being  especially  attacked.  This  is 
doubtless  due  to  the  fact  that  the  portal  of  entry  of  the  bovine  bacillus  is 
usually  through  the  tonsils  or  the  small  intestines.  Bovine  tuberculosis 
may  become  a  fatal  infection  in  man  when  it  is  generalized  through  the 
blood  in  the  form  of  acute  miliary  tuberculosis  or  when  it  localizes  in  the 
meninges  or  other  vital  parts.  About  one-quarter  to  one-third  of  all  cases 
of  tuberculosis  in  children  under  5  years  of  age  is  associated  with  the 
bovine  type.  It  is  probable  that  all  these  cases  derive  their  infection 
through  the  tubercle  bacilli  in  cow's  milk.  There  is  little  danger  from 
meat,  as  it  is  usually  cooked  and  tuberculosis  of  the  muscles  is  very  rare. 
The  following  table  ^  shows  the  relation  between  bovine  and  human 
tuberculosis  in  1,511  cases.  These  cases  were  collected  from  the  literature 
and  include  those  studied  by  the  English  and  German  Commissions;  and 
those  studied'  in  the  research  laboratory  of  the  Xcw  York  Board  of  Health 
by  Park  and  Krumwiede : 

COMBINED  TABULATION  OF  CASES  OF  TUBERCULOSIS 


Diagnosis 


Pulmonary  tuberculosis 

Tuberculous  adenitis,  axillary  or  in- 
guinal   

Tuberculous  adenitis,  cervical 

Abdominal  tuberculosis 

Generalized  tuberculosis,  alimentary 


origin 

Generalized  tuberculosis 

Generalized    tuberculosis,    including 

meninges,  alimentary  origin . . .  , 
Generalized    tuberculosis,    including 

meninges 

Tubercular  meningitis 

Tuberculosis  of  bones  and  joints . 

Genito-urinary  tuberciilosis 

Tuberculosis  of  skin 

Miscellaneous  cases: 

Tuberculosis  of  tonsils 

Tuberculosis  of  mouth  and  cervical 
nodes 

Tuberculous  sinus  or  abscess.  . 
Sepsis,  latent  bacilli 


Adults  16  Years 
and  Ove  • 


Human 


36 
16 


0 
29 


5 

1 
32 
22 
10 


Bovine 


Children  5  to  16 
Years 


Children  Under  5 
Years 


Human 


4 
36 

8 

3 
5 


10 
3 

41 

2 
4 


Bovine 


22 
9 


Human 


35 


17 
74 


76 
28 
27 


Bovine 


24 
14 


10 


Totals . 


940 


15 


131 


292 


76 


Mixed  or  double  infections,  11  cases  +  1,500=  1,511  total  cases, 
^Jour.  Med.  Research,  XXVI,  1  Sept.,  1912,  p.  109. 


138      DISEASES   SPREAD   THROUGH   MOUTH   AND   NOSE 

From  a  study  of  1,040  of  these  cases  wc  find: 

16  years  and  over 686  cases —  0  witli  bovine  bacilli — 1.3% 

Between  5  and  16  years 132       "    —33      "         "  "  —25.0% 

Under  5  years 120       "    —59      "         "  "  —49.1% 

It  should  be  remembered  that  many  of  the  cases  included  in  the  above 
total  were  selected  cases.  The  436  cases  studied  in  the  Research  Labora- 
tory in  New  York,  however,  were  not  selected;  of  these  cases  the  follow- 
ing were  found  associated  with  the  bovine  bacillus : 


Diagnosis 

Pulmonary  tuberculosis 

Tuberculous  adenitis,  cervical 

Abdominal  tuberculosis 

Generalized  tuberculosis 

Tubercular    meningitis    with    or    without    generahzed 

lesions 

Tuberculosis  of  bones  and  joints 


Adults 


Five  to 
Sixteen 


Under 
Five 


None 

4% 

16% 

3% 


5% 


None 

37% 
50% 
40% 


3% 


None 

57% 
68% 
26% 

15% 


Of  the  total  of  1,511  cases  we  find  the  following: 

PERCENTAGE    INCIDENCE    OF   BOVINE    INFECTION  ^ 


Diagnosis 


Adults  16 

Years  and 

Over 


Children 
5  to  16 
Years 


Children 

Under  5 

Years 


Pulmonary  tuberculosis 

Tuberculous  adenitis,  cervical 

Abdominal  tuberculosis 

Generalized  tuberculosis,  alimentary  origin 

Generalized  tuberculosis 

Generahzed    tuberculosis,    including    meninges, 
ahmentary  origin 

Tubercular  meningitis  (with  or  without  general- 
ized lesions  other  than  preceding) 

Tuberculosis  of  bones  and  joints 

Tuberculosis  of  skin 


.4% 
2.7% 

20% 

14% 
0% 

0% 

0% 
3.3% 
23% 


0% 
38% 
53% 
57% 
16% 

0% 

0% 
6.8% 
60% 


2.8% 
61% 
58% 
47% 

8.6% 

66% 

4.6% 

0% 

0% 


As  is  evident  from  the  table  summarizing  the  total  cases  reported, 
many  of  those  in  children  had  slight  or  latent  infections,  found  on  their 
Vow.  Med.  Research,  XXVII,  1,  Sept.,  1912. 


TUBBECULOSIS 


139 


(Icalh  rroin  dther  causes.     The  percentages  deduced,  therefore,  only  give 
the  incidence  of  infection,  nothing  more. 

Eastwood  and  also  Gritfith  ^  studied  a  series  of  195  deaths  from  all 
causes,  between  the  ages  of  2  and  10  years.  The  results  of  these  interest- 
ing studies  are  combined  in  the  following  table : 


Age  Periods 


Number  of  Cases 


Free  from 

Tubercle 

Bacilli 


Tubercle 
Bacilli 
Dead 


Tubercle 
Bacilli 
Living 


Classification  of  Cultures  Isolated 


Bovine 


Human 


Mixed 

Bovine  and 

Human 


2 —  3  years 

3 —  4  years 

4 —  5  years 

5 —  6  years 

6 —  7  years 

7 —  8  years 

8 —  9  years 
9 — 10  years 


27 

12 

14 

12 

1 

3 

4 

4 


19 

21 

14 

15 

16 

2 

4 

7 


77 


20 


98 


17 


80 


It  will  be  noted  that  of  the  total  of  195  children,  118,  or  60.5  per  cent., 
showed  evidence  of  tuberculous  infection.  The  condition  found  in  the 
118  was  as  follows:  In  92  (47.2  per  cent,  of  195  or  78.0  per  cent,  of 
118)  tuberculous  lesions,  verified  by  subsequent  cultures,  were  found,  in 
six  (3.1  per  cent,  of  195  or  5.1  per  cent,  of  118)  living  bacilli  were  ob- 
tained in  culture,  but  there  were  no  tuberculous  lesions;  and  in  20  (10.3 
per  cent,  of  195  or  16.9  per  cent,  of  118)  tuberculous  lesions  were  present, 
but  the  tubercle  bacilli  apparently  were  dead.  One  of  the  interesting 
features  of  this  investigation  is  that  living  tubercle  bacilli  may  be  present 
in  children  in  the  absence  of  lesions,  and  on  the  other  hand,  tuberculous 
lesions  may  be  present  while  the  bacilli  responsible  for  them  may  be  dead. 

Weber,  of  the  Imperial  Board  of  Health  of  Germany,  has  made  obser- 
vations to  determine  just  how  much  danger  there  is  in  drinking  milk 
containing  bovine  tubercle  bacilli.  The  milk  coming  from  all  known 
cases  of  udder  tuberculosis  was  traced  to  the  consumer  and  all  the  persons 
drinking  such  milk  or  using  fresh  milk  products  from  infected  sources 
were  examined  with  reference  to  tuberculosis.  In  all  113  separate  inves- 
tigations were  made,  including  628  persons  (284  of  whom  were  children, 
335  were  adults,  and  9  of  unstated  age),  all  of  whom  had  undoubted 
opportunities  of  consuming  milk  or  fresh  milk  products  from  cows  hav- 
ing tuberculosis  of  the  udder.     The  evidence  presented  is  not  equally 


^  Reports  to  the  Local  Government  Board  on  Pub.  Health  and  Med.  Subjects. 
London,  1914,  N.  S.,  88,   1914. 


140      DISEASES   SPHEAD   ^I^IJHOIJCH   MOU'ril   AND   NOSE 

valuable  in  each  ijivestif^aiion,  furtliermore  only  tin:  living  could  bo 
studied,  as  "there  w,\s  no  way  of  determining  how  many  may  have  died 
as  a  result  of  drinking  the  infected  milk."  In  44  of  the  113  investiga- 
tions cited,  the  milk  was  either  lieated,  used  in  coffee  or  tea,  or  mixed 
with  milk  from  apparently  tubereulosis-free  cows  before  it  was  con- 
sumed. 

Three  hundred  and  sixty  persons  (of  whom  151  were  children,  200 
adults,  and  9  of  unknown  age)  were  known  to  use  milk  or  milk  products, 
such  as  butter,  buttermilk,  sour  milk,  and  cheese,  Avhich  came  from  cows 
having  undoubted  tuberculosis  of  the  udder.  Of  these  3G0  persons  2 
were  shown,  by  actual  animal  experimentation,  to  have  infections  with 
the  bovine  tubercle  bacillus.  Both  positive  cases  w'ere  children  with 
tuberculous  neck  glands.  Six  other  children  and  1  adult  had  glandular 
swellings  in  the  neck,  and  in  4  other  children  and  1  adult  there  was  a 
strong  suspicion  on  the  part  of  the  attending  physician  that  abdominal 
tuberculosis  was  present. 

In  another  series  of  3 GO  persons,  12  children  and  1  adult  had  swellings 
of  the  lymph  glands  of  the  neck.  In  this  group  the  diagnosis  was  not 
confirmed  bacteriologically. 

Weber  concludes  from  these  studies  that  the  danger  which  man  under- 
goes through  the  consumption  of  uncooked  milk  and  milk  products  of 
cows  having  tuberculosis  of  the  udder  is  similar  to  the  danger  which 
persons  having  well-marked  pulmonary  tuberculosis  exhibit  for  their 
fellowmen,  although  very  much  less.  He  believes  it  is  fair  to  assume 
from  the  statistics  presented  above  that  the  danger  from  drinking  un- 
cooked milk  or  using  milk  products  of  cows  with  tuberculous  udders  is 
surprisingly  small. 

Woodward  voices  the  prevailing  opinion  when  he  maintains  that  the 
more  deeply  we  go  into  the  subject,  the  bovine  side  of  the  question  comes 
to  take  a  larger  and  larger  place,  especially  in  connection  with  surgical 
and  abdominal  tuberculosis,  not  only  in  the  child  but  even  in  the  adult. 

Erom  the  standpoint  of  our  present  knowledge  we  must  consider  that 
practically  every  case  of  bovine  tuberculosis  in  man  is  ingestion  tubercu- 
losis, contracted  from  milk  or  fresh  milk  products.  However,  it  may 
require  favorable  circumstances  in  the  teeth,  tonsils  or  other  portions  of 
the  digestive  tube  to  permit  the  bacilli  to  penetrate.  It  is  likely  that 
ofttimes  the  bovine  bacillus  lodges  in  the  glands  but  fails  to  set  up  disease 
on  account  of  low  virulence  or  resistance  of  the  host.  How  the  tubercle 
bacilli  get  into  milk  and  the  frequency  with  which  it  is  infected  are 
discussed  on  page  572. 

Occasionally  butchers  and  also  pathologists  at  autopsies  become  in- 
fected with  the  bovine  bacillus  through  wounds.  These  accidents  furnish 
further  experimental  proof  that  the  bovine  type  of  the  tubercle  bacillus 
possesses  a  certain  degree  of  pathogenicity  for  man. 


TUBEECULOSIS  141 

MODES  OF  INFECTION 

There  are  two  great  sources  of  human  tuberculosis :  the  principal 
source  is  man  himself;  the  secondary  source  is  cattle. 

From  man  tubercle  bacilli  leave  the  body  mainly  in  the  sputum,  where 
they  are  found  in  great  numbers  in  all  open  cases  of  pulmonary  tubercu- 
losis. Tubercle  bacilli  may  also  leave  the  body  in  the  discharges  from 
any  open  tuberculous  lesion  wherever  situated,  especially  in  discharges 
from  the  lymphatic  glands,  l)ones,  intestinal  or  genito-urinary  tracts,  or 
the  skin.  In  pulmonary  tuberculosis  some  of  the  sputum  is  swallowed 
and  the  bacilli  appear  in  the  feces,  therefore  any  or  all  of  the  discharges 
from  the  body  may  be  infective.  But,  from  the  practical  standpoint  of 
prevention,  the  bacilli  in  the  matter  brought  up  from  the  lungs  is  the 
source  of  the  danger  in  the  overwhelming  majority  of  cases. 

Practically  all  observers  agree  with  Koch  that  human  sputum  is  the 
main  source  of  human  tuberculosis.  Whether  the  tubercle  bacillus  is 
usually  transferred  directly  or  indirectly,  in  moist  or  in  dry  state,  by 
inhalation  or  ingestion,  are  questions  still  undetermined.  The  question 
at  issue  is  a  quantitative  one;  that  is,  how  often  are  we  infected  by  the 
direct  aerogenic  route,  how  often  through  the  tonsils  and  upper  respira- 
tory passages,  how  often  through  the  digestive  tube,  etc.  ? 

Aerogenic  Infection — The  Cornet-Koch  Theory. — The  belief  that 
tuberculosis  is  air-borne,  that  is,  that  pulmonary  tuberculosis  is  a  primary 
inhalation  infection,  has  long  been  the  natural  and  favorite  theory, 
from  the  fact  that  the  lungs  are  most  frequently  affected.  This  opinion 
was  strongly  expressed  by  Koch  in  1884,  and  repeated  by  him  in  1901,  at 
the  British  Congress  on  Tuberculosis.  For  many  years  it  found  prac- 
tically universal  acceptance.  Cornet  taught  that  the  tubercle  bacilli 
entered  the  lungs  in  the  dust  of  dried  and  pulverized  sputum. 

The  evidence  of  pathologic  anatomy  stren^gthens  the  belief  in  the 
importance  of  aerogenic  infections  as  the  chief  portal  of  entry.  Thus, 
the  recent  studies  by  Ghon,^  at  the  St.  Anne's  Children's  Hospital  in 
Vienna,  indicate  very  strongly  that  the  actual  path  of  infection  is  by  the 
air  passages.  Approximately  95  per  cent,  of  184  autopsies  studied  by 
him  represent  a  primary  localization  of  the  bacilli  in  the  lungs.  On  the 
other  hand,  it  seems  that  direct  aerogenic  infection  has  been  greatly  over- 
estimated, and  some  students  of  the  subject  go  so  far  as  to  state  it  is  of 
little  or  no  practical  importance.  It  is  supposed  that  very  few  bacteria 
suspended  in  the  air  actually  reach  the  lungs,  being  caught  on  the  moist 
mucous  membranes  of  the  upper  air  passages.  Further,  tuberculosis  of 
the  lungs  is  usually  at  the  apex,  which  is  not  in  the  direct  line  that  float- 
ing particles  in  the  air  would  usually  be  mechanically  carried.  It  is  true 
that  dust  under  certain  conditions  may  contain  tubercle  bacilli,  but  it  is 
"Der  primare  Lungenherd  liei  der  Tuberkulose  der  Kinder,"  Rprlin.  ]n]2. 


143      DISEASES   SPliEAD   TITROUail   MOTJTTI   A^T)   NOSI^] 

now  known  that  this  organism  soon  dies  when  exposed  to  the  sun  and 
air,  and  that  the  dust  out  of  doors  is  not  apt  to  contain  the  live  bacilli, 
and  when  it  does  so  the  dilution  must  he  enormous.  It  is  different  with 
house  dust.  Tubercle  bacilli  may  live  a  long  time  in  dark,  moist  places, 
but  even  here  the  danger  cannot  be  as  great  as  might  be  supposed  when 
we  study  the  nature  of  tuberculous  sputum.  This  substance  is  usually 
tenacious  and  gummy,  and  dries  into  tough,  glue-like  masses,  which  are 
pulverized  with  great  difficulty.  It  therefore  seems  unlikely  tliat  dust 
under  ordinary  circumstances  would  contain  dangerous  numbers  of  live 
tubercle  bacilli.  The  danger  from  this  source  is  further  diminished  when 
we  consider  that  a  large  number  of  tubercle  bacilli  die  in  sputum  even 
when  protected  from  sunlight  and  other  injurious  influences.  It  is  noAV 
known  that  even  under  most  favorable  conditions  in  artificial  culture 
media  the  great  majority,  perhaps  99  per  cent.,  of  the  bacilli  die  within 
three  months.  Transplants  made  from  cultures  over  three  months  old 
usually  do  not  grow.  The  danger  of  house  dust  containing  live  tubercle 
bacilli  from  a  quantitative  standpoint  is,  therefore,  reduced. 

A  dusty  atmosphere,  even  though  it  contains  no  tubercle  bacilli,  is, 
however,  exceedingly  dangerous,  in  that  it  irritates  the  delicate  mucous 
membranes  and  thus  opens  the  door  for  infection. 

One  point  of  importance  in  this  controversy  is  the  experimental  evi- 
dence that  it  requires  very  few  tubercle  bacilli  by  inhalation  to  produce 
the  disease,  whereas  it  may  require  hundreds  and  even  thousands  to  cause 
infection  by  the  mouth.  This  is  given  as  a  reason  why  infection  via  the 
digestive  tract  is  comparatively  rare  in  man,  for  he  fortunately  would 
seldom  swallow  the  necessary  numbers  of  human  bacilli. 

Cornet  and  others  have  actually  found  live  tubercle  bacilli  in  the  dust 
and  upon  objects  of  rooms  where  tuberculous  patients  are  careless  with 
their  sputum.  In  one  of  Cornet's  experiments  47  out  of  48  guinea-pigs 
exposed  to  the  dust  produced  by  sweeping  a  carpet  with  a  stiff  broom 
became  tuberculous.  The  carpet  had  been  purposely  infected  with  tuber- 
culous sputum  shortly  before.  Dust  containing  tubercle  bacilli  may  also 
enter  the  atmosphere  from  soiled  linen,  upholstery,  handkerchiefs,  and 
other  fabrics  containing  the  dried  tuberculous  sputum.  Tuberculous  dust 
may  also  be  stirred  up  by  walking  over  floors  and  the  dragging  of  the 
infection  by  ladies'  skirts.  Crawling  infants  are  exposed  to  especial 
danger  of  infection.  They  get  the  fresh  virulent  material  on  their  hands, 
which  are  then  carried  to  the  mouth.  It  is  now  believed  that  most  cases 
of  tuberculosis  are  contracted  in  infancy,  but  develop  later. 

Droplet  Infection. — When  it  was  found  that  the  danger  from  dust 
theoretically  was  not  as  great  as  was  supposed,  Fliigge  called  attention 
to  the  fact  that  in  speaking,  coughing,  sneezing,  and  in  other  violent 
expiratory  efforts  the  fluid  contents  of  the  mouth  are  sprayed  into  the 
air  in  the  form  of  a  fine  mist.     These  tiny  droplets  contain  tubercle 


TUBEECULOSIS  143 

bacilli  or  germs  of  any  other  infection  that  may  be  in  the  mouth.  Ordi- 
narily these  droplets  are  carried  several  feet,  but  under  exceptional  cir- 
cumstances may  be  carried  30  or  40  feet  or  more;  however,  at  these 
distances  the  dilution  is  enormous  and  the  danger,  therefore,  much 
diminished.  The  tubercle  bacilli  contained  in  the  droplets  sprayed  from 
the  mouth  are  fresh  and  virulent,  and  may  land  directly  upon  the  mucous 
membranes  of  the  healthy  individual  or  may  be  conveyed  indirectly 
through  food,  fingers,  and  other  objects.  There  is  danger  from  droplet 
infection,  but  it  cannot  be  the  usual  mode  of  transmission  in  tuberculosis 
from  the  nature  of  the  circumstances.  The  danger  from  droplet  infec- 
tion is  increased  by  close  association  with  the  patient  in  stuffy,  ill-venti- 
lated rooms,  especially  if  the  individual  does  not  take  proper  care  in 
coughing  and  sneezing.  For  a  further  discussion  of  droplet  infection 
see  page  719. 

Ingestion  Infection. — Little  by  little  the  view  gained  ground  that 
some  cases  of  tuberculosis,  particularly  in  children,  might  be  due  to 
bacilli  entering  through  the  mucous  membrane  of  the  alimentary  canal. 
JSTow  we  recognize  that  much  of  the  tuberculosis  in  children  comes  through 
the  alimentary  tract.  Many  years  before  the  discovery  of  the  tubercle 
bacillus  Chauveau  (1868)  was  inclined  to  the  belief  that  the  alimentary 
canal  may  be  the  portal  of  entry  in  tuberculosis.  "Woodward  in  1894 
maintained  that  the  infecting  bacilli  might  reach  the  lungs  through  some 
part  of  the  alimentary  canal.  He  drew  attention  to  the  fact  that  in  many 
children,  and  also  in  animals  fed  on  tuberculous  material,  the  lungs  may 
be  markedly  affected.  He  traced  the  course  of  the  infection  through 
caseous  or  old  calcareous  mesenteric  glands  iip  through  the  diaphragm 
to  the  posterior  mediastinal  glands,  and  so  to  the  lungs.  Still  in  1899 
analyzed  259  fatal  cases  of  tuberculosis  occurring  in  the  Hospital  for 
Sick  Children,  London,  and  concluded  that  the  infection  had  occurred 
through  the  alimentary  canal  in  20.5  per  cent,  of  the  eases.  Shennan  in 
1900,  dealing  with  316  autopsies  at  the  Boyal  Hospital  for  Sick  Children 
in  Edinburgh,  found  this  ratio  to  be  28.1  per  cent. 

There  is  no  doubt  that  the  lungs  are  more  or  less  involved  in  all  cases 
of  generalized  infection,  especially  in  children,  bvit  these  are  not  cases  of 
pulmonary  tuberculosis  (phthisis)  in  the  usual  meaning  of  the  term.  It 
is  phthisis  or  pulmonary  tuberculosis  which  causes  70  per  cent,  of  all  the 
mortality  from  tuberculosis  and  whose  mode  of  origin  is  now  in  question. 

Behring  in  1903  maintained  that  the  tubercle  bacilli  might  be  taken 
up  from  the  intestine  and  pass  through  the  mesenteric  glands,  so  gaining 
access  by  the  blood  stream  to  the  lungs  without  leaving  any  lesion  in  the 
gut  or  glands  to  mark  the  portal  through  which  they  had  entered  or  the 
route  by  which  they  had  traveled,  and  that  pulmonary  tuberculosis  was 
commonly  caused  in  this  way.  Behring's  theory  of  the  origin  of  phthisis 
did  not  find  a  ready  acceptance.     Nevertheless,  the  belief  that  phthisis 


144      DISEASES    SPREAD   ^rilUOUGH   MOUTH   AND   NOSE 

may  be  caused  by  bacilli  which  have  been  swallowed  and  absorbed  from 
the  digestive  tube  gradually  gained  ground.  Vallee  in  1904  concluded 
from  his  own  investigations  that  ingestion  of  dust  or  food  infected  with 
tubercle  bacilli  was  the  quickest  and  surest  method  of  infection,  A  little 
later  Calmette  (1905)  of  Lille  appeared  as  a  strong  supporter  of  this 
view.  Calmette  went  so  far  as  to  assert  that  the  immense  majority  of 
cases  of  pulmonary  tuberculosis  in  man  are  caused  by  ingested  bacilli  and 
not  by  inhalation.  Whitla,  in  1908,  and  Symmers  repeated  some  of  this 
work  and  became  converted  to  Calmette's  doctrine,  and  these  views  have 
gained  a  number  of  adherents.  Cobbett  (1910)  considers  that  the  inges- 
tion theory  is  based  on  a  slender  substructure  of  experiments  from  which 
too  sweeping  conclusions  have  been  found.  Thus  Calmette  and  his  col- 
leagues claim  that  even  anthracosis  is  caused  not  by  the  carbon  particles 
inhaled,  but  the  particles  ingested,  which  pass  through  the  intestinal 
mucosa  and  lodge  in  the  lungs.  Cobbett  showed  the  experimental  error 
and  demonstrated  that  India  ink  intimately  mixed  with  cream  is  not 
absorbed  in  any  great  amount  from  the  intestine,  for  the  cream  reappears 
of  a  normal  color  in  the  lacteals.  He  fomid,  however,  that  feeding  finely 
divided  carbon  matter  caused  traces  of  pigmentation  in  the  lung  and 
bronchial  glands  when  long  continued.  Heller  and  Vulcanstein  showed 
that  the  feeding  of  large  amounts  of  coal  dust  never  produces  that  grade 
of  anthracosis  which  is  found  after  the  inhalation  of  much  smaller 
amounts. 

There  is  now  sufficient  proof  to  state  definitely  that  tubercle  bacilli, 
when  taken  in  food  or  drink,  may  pierce  the  mucous  membrane  of  the 
digestive  tube  and  produce  lesions  in  distant  parts  of  the  body.  It  is  also 
demonstrated  that  the  tubercle  bacillus  may  thus  travel  without  leaving 
macroscopic  evidence  of  its  passage  in  its  wake.  Fraenkel  ^  and  others 
have  shown  that  the  tul^ercle  bacilli  may  pass  through  the  uninjured  skin 
of  guinea-pigs,  leaving  no  trace  of  their  passage  at  the  place  where  they 
had  been  rubbed  upon  the  skin,  but  caused  tuberculosis  of  the  internal 
organs.  Ravenel  and  others  have  shown  that  tulxTcle  bacilli  may  pas^ 
through  the  intestinal  wall  without  lea^•ing  a  trail  behind  them.  It  does 
not,  therefore,  necessarily  follow  that  the  seat  of  the  primary  lesion  in 
tuberculosis  is  the  site  of  the  entrance  of  the  infection. 

It  is  also  claimed  that,  no  matter  how  the  tubercle  bacillus  reaches  us, 
whether  in  dust  or  droplets,  by  kissing  or  through  fingers,  flies,  cups, 
handkerchiefs,  or  milk,  it  either  passes  through  the  tonsils  or  mucous 
membrane  of  the  upper  respiratory  passages,  or  is  carried  into  the  intes- 
tinal tract  and  absorbed  from  the  intestines.  Viewed  in  this  light,  the 
portal  of  entry  even  in  dust  infection  may  be  through  ingestion  rather 
than  through  direct  aerogenic  infection  of  the  lungs.  Experimentally  it 
is  easy  to  prove  that  tubercle  bacilli  given  by  tlie  mouth  may  produce  a 

^Hyg.  Rundschau,  XX,  15,  Aug.  1,  1910,  p.  817. 


TUBEECULOSIS  145 

generalized  aud  fatal  tuberculosis;  thus,  of  100  guinea-pigs  given  one 
large  feeding  of  a  bovine  culture  by  Eosenau  and  Anderson,  99  died  of 
tuberculosis.  That  infection  by  ingestion  does  not  tell  the  whole  story  is 
judged  from  the  fact  that  primary  tuberculosis  of  the  mesenteric  nodes  in 
man  is  not  as  common  as  we  might  expect.  On  the  other  hand,  it  is 
claimed  that  the  tubercle  bacillus  may  pass  these  lymph  glands,  leaving 
little  or  no  trace  behind  them.  Thus  the  work  of  Weichselbaum  and  his 
pupils,  Bartel,  Neuman,  and  Spieler,  strengthens  the  importance  of 
ingestion  as  the  portal  of  entry.  These  investigators  found  that  the 
tubercle  bacillus  produces,  in  addition  to  the  specific  tubercles,  other 
lesions  of  a  simple  lymphatic  hyperplastic  character.  These  early  lesions 
are  called  the  "lymphoid  stage"  ("'lymphoide  stadium'').  The  recogni- 
tion of  this  early  stage  is  of  importance  in  determining  the  point  of 
invasion.  The  evidence  obtained  from  the  macroscopic  appearance  of 
the  lesions  at  autopsy  must  be  supplemented  by  microscopic  studies. 
Bartel  and  Spieler  found  that  in  ingestion  experiments  the  different 
lymphatic  groups  were  infected  with  the  following  frequency,  judged  by 
the  lymj)hoid  stage : 

Tonsils  and   surrounding.  . .    11.7  per  cent. 

Cervical  glands 58.8  per  cent. 

Bronchial  glands .   52.9  per  cent. 

Mesenteric  glands 100.0  per  cent. 

These  investigators  assume  that  the  tubercle  bacillus  is  carried  from 
the  mesenteric  or  the  neck  glands  either  through  the  lymphatics  directly 
or  through  the  thoracic  duct  and  the  arterial  circulation  to  the  lungs  and 
other  tissues  and  organs  of  the  body.  The  disease  usually  localizes  itself 
in  the  lung  because  this  organ  presents  the  least  resistance. 

Weichselbaum  believes  that  ingestion  tubercidosis  occurs  much  more 
often  in  man  than  is  commonly  supposed  and  especially  in  cliildren.  He 
assumes  that  the  tubercle  bacilli  may  pass  through  the  mouth,  nose,  or 
throat.  It  seems  immaterial  whether  the  bacillus  is  taken  with  food  or 
other  substances  placed  in  the  mouth,  or  is  contained  in  the  inspired  air, 
or  enters  the  mouth  and  nose  through  any  other  medium.  The  first 
lesions  do  not  consist  in  the  formation  of  specific  tubercles,  but  in  the 
so-called  lymphatic  tuberculosis.  This  stage  lasts  a  variable  time  and 
may  end  in  recovery  or  may  lead  to  specific  tuberculosis  either  through 
reinfection,  or  it  may  light  up  itself  without  a  new  infection.  The  specific 
tubercles  may  occur  either  at  the  portal  of  entry  or  in  the  lungs  and 
bronchial  glands  or  in  other  organs. 

Behring  (1903)  brought  forward  the  theory  that  alimentary  infection 
occurs  in  the  early  months  of  life.  The  tender  nuicous  membrane  of 
babies  permits  the  bacillus  to  pass  readily.     The  bacilli  remain  latent  in 


146      DISEASES   SPKEAD   THROUGH   MOUTH   AND   NOSE 

the  tissues  and  acquire  increased  activity  later  in  life.  According  to  this 
view  tuberculosis  of  adults  is  the  "end  of  a  song,  the  beginning  of  which 
for  the  unfortunate  patient  was  sung  in  tbe  cradle." 

It  is  clear  from  the  evidence;  at  hand  tiiat  pnlnionaiy  1  iilicriMdosis  may 
arise  either  by  inhalation  or  by  ijigeslion.  'I'he  probleiu  iov  us  now  to 
solve  is  a  quantitative  one;  that  is,  Avhat  percentage  of  cases  are  air-borne 
and  what  percentage  come  through  the  mucosa  of  the  digestive  tract? 
Opinions  differ  widely,  but  opinions  are  of  little  value.  We  must  have 
the  facts  before  we  can  give  the  final  answer  to  this  very  important  and 
practical  question.^ 

Flies. — Under  certain  circumstances  flies  may  readily  transfer  tuber- 
cle bacilli  from  exposed  sputum  to  fingers,  lips,  or  food.  This  may 
account  for  an  occasional  case. 

Water. — Large  quantities  of  tuberculous  sputum  that  escape  disinfec- 
tion and  an  additional  large  number  of  tubercle  bacilli  in  the  excreta 
finally  reach  the  drinking  water.  Nearly  all  persons  with  tubercle  bacilli 
in  their  sputum,  pass  some  of  them  in  their  feces.  The  tubercle  bacillus 
is  particularly  resistant  to  putrefactive  processes,  and  may  live  a  long 
time  in  water.  The  use  of  contaminated  water  can,  therefore,  not  be 
disregarded.  A  study  of  the  vital  statistics  of  Hamburg,  Lowell,  and 
Lawrence  seems  to  show  a  diminution  in  tuberculosis  following  a  purifi- 
cation of  the  water  supply  by  filtration  (Mills-Eeinke  Phenomenon,  page 
804). 

Contact  Infection. — The  majority  of  cases  of  tuberculosis  contract 
the  disease  through  "contact."  Contact  infection  is  a  general  and  con- 
venient term;  it  implies  the  rather  quick  transference  of  fresh  infection 
in  which  the  bacilli  pass  from  one  individual  to  the  other  in  a  brief  space 
of  time  and  through  a  short  distance.  Contact  infection  may  be  either 
direct  or  indirect;  through  dust,  through  bacilli  in  the  air,  or  through 
contaminated  food,  through  soiled  fingers  or  objects;  through  files,  as 
well  as  in  numerous  other  ways.  The  infections  transferred  through  kiss- 
ing, pencils,  pipes,  toys,  cups,  and  other  objects  all  come  under  the  con- 
venient category  of  "contacts."  Even  the  infection  through  droplets  is 
included  in  the  present-day  conception  of  contact  infection.  The  term 
is  a  practical  one,  and  implies  close  association,  though  not  necessarily 
actual  contact,  between  the  sick  and  the  well.  Viewed  in  this  sense, 
tuberculosis  is  a  house  disease  or  a  family  disease.  With  this  conception 
it  makes  little  practical  difference  whether  the  infection  enters  the  body 
through  the  respiratory  tract  or  the  digestive  tube.  Either  or  both  would 
be  possible  in  regarding  the  disease  as  contagious  in  the  sense  of  contact 
infection. 

^  An  exhaustive  and  able  summary  of  this  question  will  be  found  in  Bulloch's 
article  in  Allbutt's  "System  of  Medicine^"  from  which  some  of  the  facts  in  this 
article  have  been  used. 


TUBEECULOSIS  147 

Dr.  H.  G.  Lampson  in  his  "Studies  on  the  Spread  of  Tuberculosis  in 
Five  Counties  of  Minnesota"  ^  came  to  the  conclusion  that  79  per  cent,  of 
individuals  fully  exposed  for  a  long  period  of  time  to  open  cases  of 
tuberculosis,  became  infected.  Only  28  per  cent,  of  those  partially  ex- 
posed or  exposed  for  a  short  period  of  time  became  infected.  The  per- 
centage of  infections  from  casual  exposure  such  as  ever3^one  encounters, 
was  small,  8  per  cent.  The  more  frequent  infection  of  children  is  ex- 
plained, at  least  in  part,  by  their  more  intimate  contact  with  the  patient. 
At  all  ages,  the  intimacy  and  length  of  exposure  are  the  determining 
factors  in  infection  with  tuberculosis. 

Pollak  states  that  the  earlier  the  infection  the  more  serious  the  out- 
come. This  receives  support  from  Wallgren's  statistics,  for  out  of  51 
consumptives,  15  had  been  exposed  during  the  first  5  years  of  life, 
whereas  of  the  13  healthy  persons  who  gave  a  history  of  exposure,  in  but 
1  case  had  that  exposure  been  before  the  sixth  year.  It  is  now  believed 
that  the  infection  is  usually  received  during  childhood,  but  remains  latent 
until  adolescence  or  early  adult  life,  when  the  disease  becomes  clinically 
apparent. 

Although  there  is  some  doubt  concerning  the  exact  mode  of  transmis- 
sion and  the  portal  of  entry  that  the  tubercle  bacillus  usually  takes,  we 
have  sufficient  knowledge  to  guide  our  preventive  measures  with  every 
assurance  of  success.  One  thing  is  certain:  tuberculosis  is  an  infection 
spread  mainly  from  man  to  man,  usually  through  direct  association 
between  the  sick  and  the  well ;  and  secondarily  from  cows,  through  milk. 


IMMUNITY 

Man  possesses  a  considerable  resistance  to  tuberculosis.  This  is  shown 
by  the  fact  that  many  cases  recover  spontaneously  and  that  perhaps  all 
individuals  who  reach  the  age  of  30  years  and  w^ho  spend  most  of  this 
time  in  association  with  their  fellowmen  under  the  usual  urban  condi- 
tions have  at  one  or  more  times  been  infected.  The  resistance  to  tuber- 
culosis increases  after  middle  life,  due  perhaps  to  the  immunity  which  is 
induced  by  these  prior  infections.  There  is  probably  no  true  racial  im- 
munity to  tuberculosis.  Some  races  show  a  smaller  incidence  to  the 
disease,  owing  probably  to  modes  of  life,  habits  of  nutrition,  and  condi- 
tions of  exposure.  Some  of  the  white  races  have  acquired  a  certain 
degree  of  resistance  through  inheritance  (?)  and  almost  universal  infec- 
tion.  All  races  long  removed  from  infection  are  particularly  susceptible. 

The  human  organism  is  capable  of  taking  care  of  a  certain  amount  of 
infection.  The  dose,  that  is,  the  number,  of  tubercle  bacilli  and  their 
virulence,  is,  therefore,  a  very  important  factor  in  determining  infection. 

*U.  S.  Public  Health  Reports,  Vol.  30,  No.  2,  Jan.  8,  ini5. 


148      DISEASES   SPERAD   THROUGH   MOUTH   AND   NOSE 

This  may  readily  be  demonstrated  upon  susceptible  animals  and  is  doubt- 
less true  of  man.  It  takes  at  least  ten  tubercle  bacilli  to  infect  a  guinea- 
pig.  Frequent  reinfections  occurring  at  short  intervals  with  small  num- 
bers of  tubercle  bacilli  may  break  down  the  immunity.  In  man  the  bal- 
ance between  immunity  and  susceptibility  to  tuberculosis  is  delicately 
adjusted:  there  is  a  very  small  factor  of  safety.  The  resistance  to  the 
infection  may  be  increased  by  attention  to  personal  hygiene,  fresh  air, 
and  good  food ;  immunity  may  readily  be  broken  down  by  any  weakening 
influence;  herein  lies  the  keynote  of  personal  prophylaxis. 

The  immunity  to  tuberculosis  is  not  sufficiently  strong  to  overcome 
a  large  amount  of  infection.  As  in  all  other  infectious  processes,  the 
strongest  and  most  robust  individuals  in  the  prime  of  life  succumb  to 
the  disease  in  a  short  time  if  they  receive  into  their  system  a  large  number 
of  virulent  tubercle  bacilli.  Hence  the  avoidance  of  the  infection  is  one 
of  the  most  important  of  our  preventive  measures. 

The  mechanism  of  the  immunity  to  tuberculosis  is  probably  exceed- 
ingly complex.  There  is  no  antitoxic  immunity.  The  tuberculins  are 
not  true  toxins.  Phagocytosis  and  cellular  reactions  play  a  very  impor- 
tant role.  The  recent  studies  upon  anaphylaxis  throw  a  certain  amount 
of  light  upon  the  mechanism  of  immunity  in  tuberculosis.  The  phe- 
nomenon of  hypersusceptibility  is  beautifully  illustrated  in  the  action 
of  tuberculin,  which  is  a  comparatively  harmless  substance  to  a  normal 
individual,  but  produces  a  marked  reaction  in  a  sensitized  individual. 
This  reaction  must  be  useful  in  protecting  the  organism  against  the 
invasion  of  the  tubercle  bacillus,  and  also  in  guarding  it  against  the 
spread  of  the  disease  after  it  has  become  localized.  Thus,  if  tuberculin 
is  placed  iipon  a  normal  conjunctiva  no  reaction  follows.^  This  first 
application,  however,  sensitizes  the  tissues  of  the  conjunctiva  so  that, 
if  the  application  is  repeated  after  the  lapse  of  a  few  weeks,  there  is  a 
violent  reaction.  The  same  phenomenon  doubtless  occurs  when  a  tubercle 
bacillus  lodges  in  a  lymph  gland  or  in  the  lung  or  some  other  part  of  the 
body.  The  first  time  it  meets  with  little  resistance;  the  next  time  the 
tissues  react  immediately  and  vigorously.  All  of  nature's  protecting 
agencies,  such  as  the  germicidal  substances  in  the  blood,  the  phagocytic 
cells,  and  antibodies,  are  concentrated  upon  the  point  where  they  are 
most  needed.  In  the  same  way  the  body  protects  itself  against  the  exten- 
sion of  a  tuberculous  focus.  The  parts  surrounding  a  tubercle  become 
sensitized  and  react  so  as  to  encapsulate  the  focus  with  a  cellular  and 
fibrous  coat  of  mail.  This  reaction  is  probably  stimulated  by  small 
amounts  of  tuberculin  produced  within  the  tuberculous  focus.  When 
the  tuberculin  is  not  produced  autogenously  in  sufficient  amounts,  as  in 
chronic  lesions  of  the  bones,  or  inactive  processes  of  the  glands  or  skin, 
the  specific  reaction  may  be  stimulated  to  advantage  by  the  injection  of 
*Roseriau  and  Anderson,  J.  A.  M.  A.,  Vol.  I,  March  28,  1908,  p.  901. 


TUBEECULOSIS  149 

small  quantities  of  tuberculin.  If,  however,  the  tuberculin  is  given  in 
too  large  amounts  or  too  frequently,  the  power  of  reaction  is  readily 
broken  down.  When  this  occurs  the  mechanism  of  immunity  has  been 
destroyed,  there  is  little  resistance  left  to  the  extension  of  the  infection, 
and  death  soon  occurs.  Clinical  experience  has  demonstrated  the  danger 
of  large  doses  of  tuberculin  or  small  amounts  too  often  repeated  in  tuber- 
culosis. The  same  may  readily  be  demonstrated  experimentally  in  the 
lower  animals.  These  facts  are  of  fundamental  importance  in  the  use 
of  tuberculin. 

It  is  quite  proper  to  deny  dogmatically  the  hereditary  transmission  of 
tuberculosis  in  educational  pamphlets  for  popular  use.  The  infection 
is  not  transmitted  hereditarily,  although  it  occasionally  passes  from 
mother  to  fetus  congenitally.  Tubercle  bacilli  do  not  occur  in  the  sper- 
matozoon, and  do  not  appear  in  the  seminal  fluid.  They  are  not  found 
in  the  ovum;  in  fact,  a  tubercle  bacillus  in  the  ovum  would  doubtless 
result  in  the  death  of  the  egg.  The  bacilli,  however,  may  pass  from 
mother  to  fetus  through  the  placenta.  Warthin  shows  that  placental 
tuberculosis  is  more  common  than  is  supposed.  The  lesions  in  the  pla- 
centa are  not  those  of  typical  tubercle  formation. 

While  the  tubercle  bacillus  itself  is  rarely  transmitted  from  parent 
to  offspring,  an  hereditary  tendency  or  disposition  to  the  disease  may  be 
transmitted.  We  have  no  definite  knowledge  as  to  what  this  decreased 
resistance  consists  in ;  it  may  be  a  diminished  power  of  reaction.  For  this 
view  there  is  analogy  in  the  experiments  upon  anaphylaxis  in  guinea- 
pigs,  in  which  it  has  been  shown  that  hypersusceptibility  to  a  foreign 
protein  such  as  tuberculin  may  be  transmitted  from  mother  to  young. 

A  mild  infection  with  bovine  tuberculosis  in  early  life  seems  to  leave 
a  certain  degree  of  immunity  against  the  human  strain.  At  least  persons  ■ 
who  have  glandular  tuberculosis  of  the  bovine  type  in  childhood  are  said 
to  be  less  apt  to  have  tuberculosis  of  the  lungs  in  later  life.  Likewise, 
the  human  strain  injected  into  cattle  produces  a  definite  immunity 
against  the  bovine  type.  Cattle  are  now  immunized  by  the  intravenous 
injection  of  2  c.  c.  of  a  suspension  of  a  pure  culture  of  the  human  tubercle 
bacillus.  This  produces  an  immunity  which  probably  lasts  for  1  to  2 
years.  It  should  be  remembered  that  the  human  bacillus  under  these 
circumstances  remains  alive  for  a  very  long  time,  and  may  appear  in  the 
milk  provided  there  is  a  lesion  in  the  udder.  This  presents  a  danger 
which  cannot  be  disregarded. 

Trudeau  long  ago  showed  that  the  only  definite  immunity  that  could 
be  induced  in  experimental  animals  was  through  the  use  of  live  tubercle 
bacilli.  Webb  and  Williams  ^  have  produced  a  certain  amount  of  immu- 
nity in  guinea-pigs  and  monkeys  by  the  injection  of  live  tubercle  bacilli. 

1  "Immunity  in  Tuberculosis,"  J.  A.  M.  A.,  Oct.  28,  1911,  Vol.  LVII,  No.  18, 
p.  1431. 


150      DlSh^ASKS    Sl'UKAl)   THKOUGJI    iMOU'JMT    AM)    NOSR 

'^^I'he  first  ijijcction  consists  of  the  introduction  of  n  (Vw  hiicilli  (I'l-diii 
1-200),  which  is  repeated  subcutancously  at  vai'yiiig  inlcrvyls.  'I'wd  cliil- 
dren  have  also  been  successfully  'S'accinatcd"  Avith  upward  of  600  \  indent 
Imman  tubercle  bacilli  without  infection  being  produced. 

RESISTANCE  OP  THE  VIRUS 

We  have  no  easy  method  of  determining  just  when  the  tuljercle  bacil- 
lus dies.  The  criterion  of  death  depends  upon  animal  experimentation. 
The  tubercle  bacillus  has  no  spore  and  may  be  classed  with  other  non- 
spore-bearing  organisms  so  far  as  its  viability  is  concerned.  Its  virulence 
fades  before  it  dies.  It  is  doubtful  whether  the  waxy  substances  protect 
the  bacillus  against  external  harmful  influences  to  any  unusual  extent. 
The  thermal  death  point  is  60°  C,  for  20  minutes.  This  is  much  less 
than  was  once  considered.^  Failure  to  recognize  the  lesions  produced  by 
the  dead  tubercle  bacillus  is  responsible  for  some  of  the  false  conclusions 
reached  by  experimenters  upon  this  subject. 

From  a  practical  standpoint  the  resistance  of  the  tubercle  bacillus  in 
sputum  is  of  prime  importance.  Protected  from  the  sunlight  it  is  now 
known  that  they  may  live  in  dried  sputum  for  months.  All  the  bacilli 
do  not  survive  under  these  conditions,  but  we  lack  methods  to  determine 
the  quantitative  reduction. 

The  tubercle  bacillus  withstands  cold  very  well.  It  has  a  marked 
resistance  against  putrefactive  processes.  It  will  live  a  year  in  water, 
which  is  a  fact  not  to  be  neglected,  as  many  tubercle  bacilli  finally  find 
their  way  into  drinking  water,  and  infection  through  this  source  is 
possible. 

For  the  destruction  of  the  bacilli  in  sputum  only  very  strong  germi- 
cides or  exposure  to  steam  or  boiling  water  should  be  depended  upon. 
Burning  is  the  most  practical  method  for  disposing  of  tuberculous 
sputum  (see  page  1173).  Five  per  cent,  carbolic  acid  is  sufficient,  pro- 
vided equal  parts  of  sputum  and  solution  are  mixed  and  the  exposure 
continued  for  24  hours. 

Sunlight  is  one  of  the  best  germicides  and  often  destroys  tubercle 
bacilli  quickly.  In  direct  sunlight  the  bacilli  due  in  a  few  hours,  in 
diffuse  sunlight  in  a  few  days,  provided  the  sputum  masses  are  not  too 
thick. 

PREVENTION 

Preventive  measures  are  based  upon  two  important  facts :  that  tuber- 
culosis is  an  infection  mainly  spread  from  man  to  man  through  direct 
association,  and  secondarily  from  cattle  through  infected  milk.     Pre- 

^  The  thermal  death  point  of  pathogenic  microorganisms  in  milk.  M.  J. 
Rosenau,  Hyg.  Lab.  Bull.  V.  8.  Pub.  Health  and  Mar.  Eosp.  Serv.,  No.  42. 


TUBERCULOSIS 


151 


'  ventive  measures  fall  into  two  categories:  (1)  avoiding  the  infection, 
and  (2)  increasing  resistance  through  personal  hygiene.    Both  are  neces- 

j  sary.  The  infection  may  be  avoided  through  segregation;  the  use  of 
milk  from  tuberculin-tested  cattle,  else  pasteurized;  education;  disinfec- 
tion; proper  disposal  of  tuberculous  sputum;  the  avoidance  of  contact 
with  o]3en  cases,  especially  with  those  who  do  not  use  proper  precautions ; 
early  diagnosis,  etc.  Increased  resistance  may  be  gained  through  fresh 
air,  good  food,  rest,  and  compliance  with  the  dictates  of  personal  hygiene. 
This  part  of  the  subject  includes  sociologic  and  economic  reforms,  with- 
out which  the  warfare  against  tuberculosis  cannot  succeed.  Improvement 
in  housing  conditions,  lowering  of  the  cost  of  living,  increase  in  the  scale 
of  wages,  and  all  forms  of  uplift  help  secondarily  to  diminish  the  amount 
of  the  disease.  Furthermore,  it  will  be  necessary  to  consider  secondary 
agencies,  as  preventive  clinics,  industrial  insurance,  notification,  open-air 
schools,  day  and  night  camps,  etc. 

It  is  well  to  remember  that  tuberculosis  has  gradually  declined  in 
England  and  also  in  Massachusetts  since  1850 — before  the  tubercle  bacil- 
lus was  discovered.  The  decline  was  gradual  from  1850-1885,  but  quite 
pronounced  since  that  date.     (See  Fig.  17.) 


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?IG.  17. — Showing  the  Decline  in  the  Death-Rate  from  Tuberculosis.  The  de- 
cline is  general  from  1850  until  1882,  when  the  tubercle  bacillus  was  discovered, 
since  which  time  the  decline  is  sharper. 


152      DISEASES    SPTJEAD   I'TTF^OUDTI   MOU'l'TT    AND   NOSE 

The  causes  of  this  decline  have  been  much  discussed.  It  may  be  due 
to  better  food  supply  at  all  seasons  of  the  year,  brouglit  about  by  improved 
methods  of  transportation,  and  the  general  use  of  refrigeration  and  can- 
ning; it  may  be  due  to  better  hygiene  and  sanitation;  or,  it  may  be  due 
in  part  to  the  special  antituberculosis  measures.  On  the  other  hand,  the 
decline  may  have  been  little  influenced  by  any  of  the  usually  assigned 
causes,  but  may  simply  be  a  biological  phenomenon  indicating  a  falling 
off  in  the  virulence  of  the  tubercle  bacillus. 

Segregation.  Sanatoria, — Tuberculosis  is  a  "contagious"  disease,  and 
it  is  now  perfectly  plain  that  one  of  the  most  important  single  preventive 
measures  in  this  as  in  all  other  communicable  diseases  consists  in  isola- 
tion. A  case  isolated  is  a  case  neutralized,  hence  the  great  value  to  the 
community  of  sanatorium  treatment.  Isolation  in  this  case  refers  only 
to  those  individuals  having  tubercle  bacilli  in  their  sputum,  and  especially 
to  the  advanced  and  helpless  cases.  The  power  of  forcible  removal  and 
isolation  of  the  irresponsible,  careless  or  indigent  consumptive  is  often 
essential  to  success.  The  isolation  in  tuberculosis  need  not  go  to  the 
extreme  practiced  in  the  acute  communicable  fevers.  In  fact,  Ave  cannot 
for  many  years  to  come  object  to  giving  a  case  of  open  pulmonary  tuber- 
culosis his  complete  liberty,  provided  he  is  careful  and  cleanly  and  uses 
proper  precautions  in  the  disposal  of  his  expectoration.  When  the  disease 
becomes  less  prevalent  more  stringent  and  arbitrary  measures  may  then 
be  enforced. 

Special  measures  must  be  taken  to  protect  infants  and  children 
against  the  infection. 

"Every  case  of  tuberculosis  isolated  means  an  average  of  at  least  three 
less  new  infections."  Sanatoria  should,  therefore,  be  attractive  and  as 
cheap  as  it  is  possible  to  run  them.  Free  hospital  care  for  the  incurable 
cases  is  necessary,  especially  for  the  poor.  Tuberculosis  has  diminished 
most  in  those  countries  where  sanatoria  are  most  in  use. 

Separate  sanatoria  should  be  provided  for  the  incipient  cases  and  for 
the  advanced  cases.  A  sharp  division  is  not  always  possible,  for  an. 
incipient  case  may  develop  into  an  open  case  within  a  week,  and,  on  the 
other  hand,  open  cases  may  return  to  latency  in  a  short  time.  It  is  better 
for  each  locality  to  have  its  own  sanatorium  than  to  provide  large  institu- 
tions which  become  unwieldy.  Furthermore,  tuberculosis,  like  all  other 
widespread  infections,  is  a  local  problem.  A  distant  sanatorium  will 
neither  attract,  nor  keep  the  advanced  cases,  which  are  perhaps  the  most 
dangerous  so  far  as  spreading  the  infection  is  concerned.  Persons  with 
tuberculosis  need  not  necessarily  go  to  a  sanatorium  with  the  object  of 
remaining  until  cured.  It  is  worth  while  if  they  go  there  but  for  a  few 
months  to  learn  the  methods  of  treatment  and  the  technic  of  prevention. 
While  sanatoria  should  be  well  built  and  comfortable,  extravagance  is  not 
necessary.    An  initial  expenditure  of  about  two  hundred  dollars  per  bed 


TUBERCULOSIS  153 

will  meet  all  reasonable  requirements.  Special  police  power  to  restrain 
the  incorrigible  consumptive  in  special  detention  wards  or  places  is  desir- 
able. 

Tuberculosis  Dispensaries. — Every  community  should  be  provided 
with  a  dispensary  for  diagnosis,  treatment,  and  for  teaching  the  consump- 
tive how  to  care  for  himself  at  home.  Each  dispensary  should  have  at 
least  one  physician  and  a  nurse  with  special  experience  in  the  problem. 
Much  social  service  work  can  be  done  from  such  a  dispensary,  especially 
in  following  up  cases  after  leaving  the  sanatorium. 

Associations. — Associations  for  the  cure  and  relief  of  tuberculosis  are 
essential  parts  of  the  problem,  and  such  associations  should  be  active  in 
every  community  in  order  to  obtain  hospital  accommodations  for  the 
advanced  cases,  sanatorium  treatment  for  the  hopeful  cases,  and  advice 
for  the  incipient  cases,  to  obtain  establishment  of  dispensaries,  district 
nursing  and  necessary  legislation. 

Personal  Prophylaxis. — Personal  prophylaxis  consists  in  avoiding  the 
infection  and  in  obeying  all  the  dictates  of  personal  hygiene — that  is, 
living  a  clean,  normal,  and  temperate  life. 

Close  association  with  persons  known  to  have  tubercle  bacilli  in  their 
sputum  is  hazardous.  This  becomes  especially  dangerous  when  the  con- 
tact is  prolonged  and  intimate,  such  as  working  in  the  same  room,  espe- 
cially if  it  is  small  and  ill-ventilated,  or  living  in  the  same  house,  sleeping 
in  the  same  bed.  The  more  intimate  the  association  and  the  less  care 
the  tuberculous  individual  takes  with  the  expectoration,  the  greater  is  the 
danger.  The  danger  diminishes  somewhat  with  age ;  infants  and  children 
need  special  protection.  The  infection  may  further  be  avoided  by  refus- 
ing to  drink  from  common  cups,  by  taking  care  in  placing  objects  to  the 
mouth  that  do  not  belong  there,  by  avoiding  dusty  atmospheres,  and 
refusing  to  drink  milk  that  does  not  come  from  tuberculin-tested  cattle 
unless  it  is  pasteurized. 

Mechanical  obstructions  to  breathing  should  be  corrected,  by  surgical 
methods  if  necessary.  Functional  lack  of  proportion  in  the  chest  and 
lungs  of  young  people  favor  infection,  and  every  effort  should  be  made 
to  help  the  child  to  outgrow  them.  Breathing  exercises  and  outdoor  play 
are  especially  useful. 

A  generous  diet  is  one  of  the  best  prophylactics  against  tuberculosis. 
A  fat-rich  food  favors  the  development  of  a  water-poor  body,  and  it  is 
known  from  experimental  observation  that  animals  with  the  largest  pro- 
portion of  water  in  their  tissues  yield  to  the  infection  more  readily  than 
others. 

Eesistance  to  the  disease  is  increased  by  rest,  fresh  air,  good  food, 
sunshine,  the  avoidance  of  all  depressing  influences,  siieh  as  worry,  over- 
work, intemperance,  and  excesses  of  all  kinds.  Attention  should  be  given 
to  slight  colds  and  ot1ier  conditions  known  to  be  predisposing  causes  to 


154      DISEASES   SPREAD   THROUGH   MOUTH   AND   NOSE 

the  disease.  Tuberculosis  is  the  one  disease  in  wliicli  the  measures  of 
treatment  and  of  prevention  are  to  a  large  extent  identical. 

Conditions  favoring  tuberculosis  are  anemia  and  underweight,  con- 
tinuous overfatigue,  recurrent  colds,  especially  recurrent  bronchitis,  slow 
recuperation  from  any  acute  infection,  whether  influenza,  measles  or 
whooping-cough,  prolonged  sej)tic  processes,  or  typhoid  fever.  It  is  well 
to  remember  that  maturity  of  tissues,  freedom  from  trauma,  normal 
nutrition,  and  the  absence  of  intercurrent  disease  or  toxic  influences  are 
the  important  "factors  of  safety"  on  the  part  of  the  body. 

Education. — The  prevention  of  tuberculosis,  like  all  other  widespread 
infections,  depends  for  its  success  upon  the  education  of  the  people.  We 
are  now  in  possession  of  sufficient  information  of  a  precise  nature  to 
place  the  facts  in  plain  words  before  the  public.  This  has  been  done  in 
numerous  excellent  pamphlets  and  popular  articles  in  the  daily  press  and 
magazines,  through  lectures,  conferences,  moving  pictures,  exhibits,  and 
meetings,  so  that  there  is  now  a  widespread  understanding  of  the  prob- 
lem. The  modern  message  in  tuberculosis  has  been  one  of  hope,  in  that 
the  disease  is  curable;  and  one  of  fear,  in  that  it  is  transmissible.  The 
former  has  been  a  great  encouragement  and  has  added  strength  to  the 
movement;  the  latter  is  also  helpful,  although  it  has  run  to  extremes  in 
some  quarters.  An  unwarranted  fear  of  tuberculosis  (phthisiophobia) 
has  subjected  the  tuberculous  individual  to  severe  hardships  by  branding 
him  as  a  leper.  Even  cured  cases  of  the  disease  now  find  difficulty  in 
obtaining  work.  A  wholesome  regard  for  the  infection  is  useful  and 
helpful  in  preventive  medicine,  but  an  hysterical  fear  of  tuberculosis  is 
quite  as  unwarranted  as  a  total  disregard  for  the  infection. 

Notification, — Tuberculosis  should  be  included  among  the  list  of  dis- 
eases requiring  compulsory  notification.  Without  this  important  feature 
an  adequate  control  of  the  disease  cannot  be  effected.  The  objection  to 
compulsory  notification  is  based  largely  upon  sympathy  with  the  large 
number  of  individuals  affected  and  the  sensitiveness  of  the  afflicted. 
Compulsory  notification  may  result  in  individual  harm,  in  that  the 
knowledge  of  the  fact  may  result  in  loss  of  occupation  and  an  avoidance 
by  his  fellowmen  on  account  of  the  fear  people  now  have  of  associating 
with  a  tuberculous  individual.  These  effects  may,  for  the  present,  be 
neutralized  by  considering  the  records  as  confidential  communications 
between  physician  and  health  officer. 

Tuberculosis  is  required  to  be  reported  in  Maine,  Michigan,  Massa- 
chusetts (since  1907)  ;  many  cities:  Alameda,  California;  Asbury  Park, 
N.  J. ;  Boston,  Buffalo,  Cincinnati,  New  York,  Salt  Lake  City,  Trenton, 
Yonkers — also  in  Washington,  D.  C,  Minneapolis,  San  Francisco,  and 
Syracuse.  The  list  is  growing  and  the  returns  are  gradually  improv- 
ing. 

In  Eng-land  and  Wales  the  notification  of  all  forms  of  tuberculosis. 


TUBEECULOSIS  155 

whether  in  public  or  private  practice,  is  obligatory,  since  Feb.  1,  1913. 
The  information  thus  received  is  held  as  confidential. 

Disposal  of  the  Sputum. — As  the  tuberculous  sputum  is  the  principal 
source  of  the  infection,  it  should  be  disinfected  or  disposed  of  so  that 
it  will  be  harmless  to  others.  Perhaps  the  best  way  is  to  receive  the 
expectorated  matter  into  cloths,  which  may  be  burned,  or  the  material 
may  be  received  into  one  of  the  various  forms  of  sputum  cups  and 
finally  burned  or  disinfected.  Persons  with  pulmonary  tviberculosis  must 
be  warned  against  the  possible  danger  to  others  of  coughing  without 
holding  the  handkerchief  before  the  mouth  and  nose;  under  no  circum- 
stances should  they  spit  upon  the  floor.  Penalty  for  spitting  upon  the 
sidewalk,  upon  the  floor  of  public  buildings,  and  in  street  cars  serves 
a  useful  purpose  in  diminishing  the  spread  of  tuberculosis  as  well  as 
other  diseases.     (Disinfection  of  Sputum,  see  page  1173.) 

Disinfection. — Eooms  occupied  by  tuberculous  individuals  should  be 
kept  clean  and  disinfected  from  time  to  time.  A  thorough  disinfection 
and  cleansing  should  also  be  practiced  before  such  rooms  are  occupied  by 
other  persons.  This  may  be  accomplished  by  mopping  surfaces  with  the 
usual  solutions  of  bichlorid  of  mercury  or  one  of  the  coal-tar  prepara- 
tions, followed  by  formaldehyd  fumigation  and  a  mechanical  cleansing, 
and  then  a  thorough  airing  and  sunning.  Formaldehyd  gas  alone  cannot 
be  depended  upon  because  it  lacks  the  power  of  penetration. 

Early  Diagpiosis. — Early  diagnosis  plays  an  important  role  in  success- 
ful prevention;  not  only  does  it  give  the  individual  the  best  chances  of 
cure,  but  at  the  same  time  it  assures  the  possibility  of  maximum  protec- 
tion to  others.  Through  the  use  of  tuberculin  and  through  reflnements 
of  clinical  methods  it  is  now  possible  to  diagnose  tuberculosis  at  a  stage 
when  it  was  formerly  not  suspected.  It  is  a  great  mistake,  from  the 
standpoint  of  prevention,  to  wait  until  tubercle  bacilli  appear  in  the 
sputum  before  making  a  diagnosis  of  tuberculosis.  The  symptoms  that 
suggest  incipient  tuberculosis  are  rather  general  in  character.  It  is  often 
necessary  to  make  a  diagnosis  by  exclusion,  for  it  may  be  impossible  for 
the  clinician  to  state  just  where  the  process  is  located.  The  symptoms 
that  suggest  incipient  tuberculosis  are  loss  of  weight,  rise  of  temperature 
in  the  afternoon,  or  subnormal  temperature  with  rapid  pulse,  loss  of 
appetite,  languor  and  lack  of  energy,  anemia,  dyspepsia,  with  or  without 
a  cough.  Probably  many  cases  of  "a  slight  run-down  condition,"  of 
transient  and  irregular  febrile  attacks,  are  due  to  a  small  focus  of  tuber- 
culosis hidden  from  the  ken  of  the  clinician.  In  such  cases  a  course  of 
rest,  fresh  air,  and  better  food,  with  a  change  of  scene,  may  often  pre- 
vent irreparable  damage.  The  establishment  of  preventive  clinics  to 
look  after  such  cases  and  the  maintenance  of  medical  clinics  to  diagnose 
and  care  for  the  early  cases  are  important  adjuncts  to  preventive  meas- 
ures. 


150      DISEASES   SPEEAD   THROUGH   MOUTH   AND   NOSE 

Housing  Conditions. — It  has  long  been  realized,  eveu  before  the  rea- 
sons were  understood,  that  improvement  in  housing  conditions  diminishes 
the  incidence  to  tuberculosis.  This  is  a  common  observation  in  the 
stabling  of  cattle  as  well  as  the  domicile  of  man.  The  reasons  wliy 
improving  the  housing  conditions  diminishes  the  spread  of  tuberculosis 
are  complex.  In  addition  to  raising  the  standard  of  living,  better  houses 
diminish  the  chances  of  contact  infection,  afford  better  air  and  more  sun- 
shine, and  tend  generally  to  the  well-being  and  uplift  of  mankind.  jMu- 
nicipalities  do  well  to  enact  and  enforce  stringent  laws  regulating  the 
construction  of  houses,  offices,  stores,  and  workshops.  The  congested 
and  squalid  slums  are  both  a  disgrace  and  a  menace.  Germs  are  social 
climbers,  and  many  a  palace  is  invaded  with  an  infection  from  a  nearby 
neglected  alley.  Philanthropists  cannot  do  better  than  assist  in  improv- 
ing the  housing  conditions  of  the  poor. 

Care  of  the  Cases  in  the  Home. — Open  cases  of  tuberculosis  should 
not  be  cared  for  in  the  home,  but  in  case  they  are,  such  homes  should  be 
visited  by  a  social  service  nurse.  Home  visitation  is  a  simple  but  very 
powerful  means  of  attacking  this  and  other  diseases.  It  is  the  surest  way 
of  reaching  the  indifferent  and  ignorant  portion  of  the  public  which  con- 
stitutes the  great  obstacle  in  the  successful  prevention  of  disease.  Home 
visitation  is  not  merely  applicable,  but  almost  indispensable  in  many  pub- 
lic health  problems,  and  should  become  one  of  the  routine  methods  of  a 
good  public  health  organization.  Such  a  system  recognizes  the  fact  that 
tuberculosis  is  not  merely  a  bacterial  invasion,  but  a  disease  of  defective 
civilization.  Through  this  means  social  relief  may  teach  better  standards 
of  living  and  provide  better  food,  light,  air,  housing,  clothing,  and  occu- 
pation. A  study  of  tuberculosis  at  close  range  has  taught  the  lesson  of 
the  absolute  necessity  for  individualizing  the  treatment  of  each  case  in 
order  to  obtain  satisfactory  results. 

Industrial  Conditions. — Many  a  case  of  tuberculosis  is  contracted  by 
those  who  are  required  to  work  alongside  of  a  fellow  workman  who  has 
pulmonary  tuberculosis,  especially  in  crowded,  poorly  ventilated  and  in- 
sanitary workshops.  Mr.  Allen  Joslin  helped  to  suppress  the  disease 
within  two  years  at  Oxford,  Mass.,  where  tuberculosis  was  unduly  preva- 
lent, through  medical  inspection,  aided  by  a  nurse;  removing  the  sick  to 
sanatoria,  and  by  a  general  improvement  in  the  sanitary  and  hygienic 
conditions  of  the  mill.  Similar  measures  have  been  met  with  signal  suc- 
cess in  other  industrial  centers.  Much  real  good  can  be  accomplished 
along  these  lines. 

Tuberculosis  in  Children. — In  one  sense  tuberculosis  is  a  disease  of 
childhood,  for  almost  all  children  by  the  time  they  reach  fourteen  years 
of  age  react  to  tuberculin,  thus  indicating  that  they  have  become  sensi- 
tized or  "tuberculized."  Children  rarely  have  tuberculosis  of  the  kings 
(consumption)  ;  when  they  do  it  is  usually  rapidly  fatal.    It  is  hazardous 


TUBEliCULOSIS  157 

to  permit  such  children  in  schoolrooms  or  even  to  remain  at  home ;  they 
should  be  cared  for  in  sanatoria.  It  is  the  anemic,  incipient,  pretubercu- 
lar,  glandular,  or  scrofulous  type  that  demands  especial  attention.  Such 
children  are  best  cared  for  in  school-hospitals,  sometimes  called  open-air 
schools.  These  children  are  going  to  furnish  a  large  percentage  of  the 
open  pulmonary  cases  in  later  life.  In  a  school-hospital  emphasis  should 
be  laid  on  treatment,  and  the  teaching  given  secondary  consideration. 

Bovine  Tuberculosis. — The  prevention  of  bovine  tuberculosis  consists 
simply  in  using  milk,  cream,  and  fresh  milk  products  from  tuberculin- 
tested  cattle.  The  cattle  should  be  tested  frequently;  at  least  twice  a 
year,  for  the  disease  may  develop  in  the  cow  in  a  few  months.  When 
milk  is  used  from  non-tested  cattle,  it  should  be  pasteurized,  and  the 
same  precaution  applies  to  the  milk  used  for  making  cream,  butter,  ice- 
cream, and  other  fresh  milk  products. 

The  Bang  Method  of  Suppressing  Bovine  Tuberculosis. — More  work 
lias  been  done  in  Denmark  in  accordance  with  the  recommendations  of 
Bang  in  the  suppression  of  tuberculosis  of  cattle,  and  the  results  achieved 
are  of  greater  value  than  in  any  other  part  of  the  world.  The  system, 
in  short,  is  as  follows :  Herds  are  tested  with  tuberculin  upon  the  appli- 
cation of  the  owner  of  the  cattle.  After  the  test,  the  herd  is  divided  into 
two  parts,  (1)  the  healthy  section  and  (2)  the  reacting  or  tuberculous 
section.  These  herds  are,  if  possible,  kept  in  separate  buildings.  If  this 
cannot  be  done,  they  are  kept  in  separate  parts  of  the  same  building,  a 
tight  partition  separating  them.  The  milk  from  both  sections  is  used  by 
the  creameries,  but  it  is  the  almost  universal  practice  in  Denmark  to 
pasteurize  the  cream  preparatory  to  ripening  it  for  churning,  and  the  law 
requires  that  skim  milk  shall  be  heated  to  a  point  that  will  kill  the 
tubercle  bacilli  before  it  is  returned  to  the  farmers  to  be  used  for  feeding 
purposes.  The  law  further  provides  that  the  sediment  that  remains  in 
the  separator  shall  be  burned. 

The  calves  from  the  cows  in  the  reacting  sections  are  removed  from 
their  dams  immediately  after  birth  and  are  reared  on  the  milk  of  healthy 
cows  or  on  milk  that  has  been  heated.  These  calves  are  tested  when  they 
are  three  or  four  months  old,  and  if  they  do  not  react,  they  are  permitted 
to  enter  the  sound  section  of  the  herd.  x\s  a  matter  of  fact,  reactors  are 
very  rare  among  these  calves.  Most  of  them  are  born  healthy,  and  when 
cared  for  as  directed,  they  remain  free  from  tuberculosis.  All  cows  with 
tuberculosis  of  the  udder  are  required  to  be  reported  and  are  killed. 
Some  compensation  is  allowed  for  them.  The  appraisement  is  equivalent 
to  one-fourth  of  the  meat  value  of  the  animal.  The  other  tubercular 
cattle  in  the  reacting  section  are  examined  physically  from  time  to  time 
and  killed  in  public  abattoirs  under  veterinary  control.  Their  flesh  is 
then  disposed  of  in  accordance  with  the  recommendation  of  the  inspector. 
Some  of  it  is  seized  and  destro^^ed,  some  of  it  is  sold  for  food.     The  law 


158      DISEASES   SPEEAD   THEOUGH   MOUTH   AND   NOSE 

I'lirthcr  ))r()vi(les  tliat  cattle  brought  into  Denmark  shall  he  kept  in  quar- 
antine until  tested  with  tuberculin  and  found  free  from  tuberculosis. 

]\lany  herds  have  been  tested  in  Denmark  with  negative  results,  prov- 
ing that  tuberculosis  is  not  a  necessary  disease  among  highly  developed 
dairy  cattle,  and  that  the  tubercle  bacilli  are  not  omnipresent. 

Industrial  Insurance. — Industrial  insurance  patterned  after  the  plan 
used  in  Germany  is  a  useful  adjunct  in  the  fight  against  tuberculosis. 
The  German  industrial  associations  under  government  supervision  do 
more  than  care  for  the  tuberculous  workman.  The  heavy  drains  upon 
the  funds  of  the  industrial  associations  have  been  checked  by  the  estab- 
lishment of  "preventoria."  These  are  attractive  country  places  where 
the  working  man  can  go  when  he  is  "run  down."  This  simple  measure 
is  a  great  boon,  and  prevents  the  development  of  many  a  case  of  tubercu- 
losis as  well  as  other  diseases. 

Org"anizing  a  Local  Tuberculosis  Campaign. — Tuberculosis  being  a 
local  problem  should  be  attacked  by  every  town  throughout  the  country. 
The  method  of  organizing  a  tuberculosis  campaign  is  first  to  interest  a 
number  of  different  agencies,  such  as  the  church,  business,  doctors,  politi- 
cians, women's  clubs,  the  press,  and  the  board  of  health.  This  beginning 
can  best  be  done  by  one  person  who  will  devote  himself  or  herself  to  the 
work.  After  the  press  has  printed  a  few  articles  on  tuberculosis  and  the 
pulpit  has  helped  to  emphasize  the  importance  of  the  movement,  a  local 
committee  should  then  be  formed  to  invite  a  tuberculosis  exhibit.  These 
exhibits  may  be  obtained  either  from  the  National  Association  for  Tuber- 
culosis, or  from  most  of  the  state  boards  of  health.  It  will  require  at 
least  one  hundred  and  fifty  dollars  to  finance  such  an  exhibit.  A  tubercu- 
losis society  should  then  be  formed.  The  next  step  is  to  establish  a  dispen- 
sary with  a  physician  and  a  nurse.  An  efficient  nurse  with  social  service 
training  is  essential  for  the  success  of  the  movement.  After  this  is  well 
under  way,  a  day  camp  should  be  started  in  a  modest  way  at  a  convenient 
locality,  and,  should  this  succeed,  a  night  camp  may  be  added.  A  day 
and  a  night  camp  is  the  equivalent  of  a  local  sanatorium.  This  much 
can  be  done  by  voluntary  efforts  and  private  subscription,  but  at  this 
point  the  town  authorities  should  take  over  the  work. 

Summary. — The  prevention  of  tuberculosis  is  no  longer  solely  a  med- 
ical problem  but  largely  a  sociological  problem.  It  is  a  disease  of  defec- 
tive society.  Its  eradication  will,  however,  take  time  on  account  of  the 
chronic  nature  of  the  disease  and  its  widespread  prevalence.  We  should 
be  satisfied  if  we  diminish  the  amount  of  tuberculosis  appreciably  in  a 
generation.  The  momentum  thus  gained  will  increase  rapidly.  The  time 
will  come  when  the  comparatively  few  cases  left  may  be  treated 
by  compulsory  isolation  or  other  aggressive  measures.  Persistence  along 
the  lines  now  understood  will  in  time  control  the  disease,  which  will  be 
the  crowning  achievement  in  preventive  medicine. 


DIPHTHERIA  159 


DIPHTHERIA 


Our  knowledge  of  diphtheria  is  most  satisfactory  in  that  we  know  the 
cause  of  the  disease  and  its  modes  of  transmission;  we  are  able  to  check 
its  spread,  and  possess  a  specific  preventive  and  curative  agent  of  great 
potency. 

Diphtheria  spreads  slowly  from  person  to  person  and  from  community 
to  community.  It  is  not  necessary  to  consider  it  endemic  in  special 
indigenous  foci,  because  it  is  never  completely  absent  in  any  large  com- 
munity. Newsholme  points  out  that  diphtheria  epidemics  and  pandemics 
occur  cyclically.  The  intervals  between  the  years  of  epidemic  prevalence 
vary  greatly.  In  Boston  diphtheria  was  epidemic  in  1863-G4,  1875-76, 
1880-81,  1889-90,  and  1894;  in  New  York  in  1876-78,  1880-82,  1886-88, 
and  1893-94;  in  Chicago  in  1860-65,  1869-70,  1876-79-81,  1886-87,  and 
1890.  The  causes  of  these  epidemic  outbursts  are  not  clear.  They  may 
be  due  to  a  fortuitous  combination  of  such  circumstances  as  a  new  crop 
of  susceptible  children,  a  particularly  virulent  strain  of  the  bacillus,  the 
opening  of  the  schools,  and  similar  factors  favoring  the  spread  of  the 
infection.  On  the  other  hand,  external  conditions,  such  as  dryness,  may 
be  important,  for  ISTewsholme  states  that  "diphtheria  only  becomes  epi- 
demic in  years  in  which  the  rainfall  is  deficient.  There  is  no  instance  of 
a  succession  of  wet  years  in  which  diphtheria  was  epidemic."  It  is  more 
than  likely  that  the  great  outbreaks  are  due  to  a  combination  of  the  three 
factors  (1)  man,  (2)  the  bacillus,  and  (3)  the  environment.  Just  as  a 
spark  in  a  forest  may  cause  a  brush  fire  or  a  conflagration,  depending 
upon  the  amount  of  plant  growth,  its  distribution,  its  condition  as  to 
dryness,  the  direction  and  force  of  the  wind,  the  topography  and  nature 
of  the  soil,  and  many  other  conditions,  so  diphtheria  and  other  infections 
will  smolder  or  burst  into  flame,  depending  upon  many  factors. 

Diphtheria  is  said  to  prevail  more  in  rural  than  in  urban  districts. 
Sir  George  Buchanan  first  pointed  out  that  it  has  always  displayed  a. 
more  marked  tendency  to  prevail  in  sparsely  settled  districts  than  in 
centers  of  population,  although  outbreaks  in  congested  centers,  schools, 
camps,  on  board  ships,  and  in  other  crowded  places,  are  common.  In 
the  tropics  diphtheria  is  practically  absent.  JSTewsholme  pointed  out  that 
it  is  more  of  a  continental  than  an  insular  disease.  The  fatality  from 
diphtheria  has  been  greatly  lowered  since  1894,  owing  to  the  use  of  anti- 
toxin and  to  refinements  of  diagnosis,  as  a  result  of  which  many  mild 
cases  are  now  included  that  were  formerly  omitted  from  the  statistical 
records.  Whether  or  not  there  has  been  a  natural  tendency  for  the  disease 
to  become  milder  in  recent  years  cannot  be  stated. 

Diphtheria  reaches  its  maximum  prevalence  in  the  autumn  of  each 
year,  which  corresponds  to  the  seasonal  prevalence  of  scarlet  fever.   Diph- 


160      DISEASES   SPEEAD   THROUCII   MOlJ^rii   AND   NOSE 


theria  is  a  cold  weather  disease.  The  iiifhienee  of  climate  is  confirmed  hy 
its  rare  iiicidciice  in  the  tropics.  While  the  seasonal  prevalence  is  in  the 
colder  montlis,  an  epidemic  once  estahlished  may  go  on  regardless  of 
season,  reaching  its  maximum  at  the  period  of  higliest  tem7)eraturo. 

In  1878  Dr.  Thrushfield  published  papers  illustrating  the  way  in 
which  diphtheria  hung  about  damp  houses.     A  damp  dwelling  favors 

sore  throats  and  colds,  and 
may  thus  open  a  way  for  in- 
vasion of  the  bacilli,  just  as 
any  depressing  influence  may 
predispose  to  the  infection. 
Children  with  scarlet  fever 
or  measles  are  especially 
prone  to  take  diphtheria  .if 
the  infection  is  around.  Any 
abnormal  condition  of  the 
mucous  membrane  of  the 
throat  and  nose  favors  the 
localization  of  the  diphtheria 
bacillus,  and  may  thus  act  as 
a  predisposing  cause;  there- 
fore, sore  throat,  foreign 
bodies,  adenoids,  as  well  as 
dust  or  any  i:;ritant,  may 
predispose  to  the  disease  if 
the  diphtheria  bacillus  is 
present.  Formerly  imperfect 
drains  and  sewer  gas  were 
given  as  the  causes  of  diph- 
theria; this  is  a  fetish  which 
dies  hard. 

Modes  of  Transmission. — 
The  diphtheria  bacillus  usu- 
ally enters  by  the  mouth  or 
nose,  and  the  lesions  are  usu- 
ally localized  in  the  mucous 
membranes  of  the  throat, 
nose,  larynx,  or  upper  respiratory  tract.  The  bacillus  leaves  the  body  in 
the  discharges  from  the  mouth  and  nose.  Diphtheria  occasionally  affects 
other  mucous  membranes  or  abraded  surfaces,  such  as  the  conjunctiva  or 
vaginal  mucous  membrane,  or  open  wounds,  the  discharges  from  these 
lesions  containing  the  infective  agent. 

The  bacillus  may  be  transmitted  directly  from  one  person  to  another, 
as  by  kissing;  exposure  to  droplet  infection  in  coughing;  speaking;  sneez- 


JA« 

Ffeb, 

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Apr. 

M&tj 

June 

Juli^ 

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Sept 

Oct 

Nov 

Dec 

14000 

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Fig.  18. — Chart  Computed  from  the  United 
States  Census  Report  to  Show  How  the 
Opening  of  the  Schools  in  Autumn  In- 
creases Diphtheria. 

The  broken  line  shows  the  number  of  cases  among 
school  children  five  to  fourteen  years  old  dur- 
ing 1900-1904  in  the  registration  area  of  the 
United  States.  The  unbroken  line  shows  the 
number  of  eases  among  children,  from  birth  to 
five  years  of  age,  for  same  period  and  area. 

On  this  chart  the  augmented  increase  in  diphtheria 
among  school  children  from  five  to  fourteen 
years  of  age,  as  compared  with  children  under 
five  years,  is  strikingly  shown. 

(Mass.  State  Board  of  Health,  Monthly  Bull.,  Sept. 
1910.) 


DIPHTHEEIA  161 

ing ;  or  the  infection  may  be  conveyed  indirectly  from  one  person  to  an- 
other in  many  ways;  most  common  among  children,  perhaps,  are  toys, 
slate  pencils,  food,  fingers,  handkerchiefs,  or  other  objects  that  have  been 
mouthed  first  by  the  infected  child  and  then  by  the  susceptible  child. 
Experience  points  clearly  to  the  conclusion  that  diphtheria  is  transmitted 
usually  by  a  direct  exchange  of  the  flora  of  the  nose  and  throat,  rather 
than  indirectly  through  inanimate  objects.  Bacillus  carriers  play  a  large 
role  in  spreading  the  infection.  Milk  and  other  foods  may  become  in- 
fected and  transmit  the  disease.  The  diphtheria  bacillus  is  frail  and  soon 
dies  when  dried  or  exposed  to  sunlight,  therefore  air-borne  infection  is 
probable  only  in  the  case  of  close  association,  that  is,  within  a  few  feet 
of  the  infected  person  and  within  the  radius  of  the  possibility  of  droplet 
infection. 

Experience  clearly  teaches'  that  diphtheria  is  spread  mainly  by  the 
active  cases;  recent  convalescents;  mild  and  missed  cases;  and  carriers. 

The  following  description  by  Chapin  illustrates  how  diphtheria  and 
all  other  infections  contained  in  the  secretions  from  the  mouth  and  nose 
may  be  transmitted;  it  also  emphasizes  the  importance  of  education  in 
personal  hygiene  based  upon  habits  of  biological  cleanliness : 

"Not  only  is  the  saliva  made  use  of  for  a  great  variety  of  purposes, 
and  numberless  articles  are  for  one  reason  or  another  placed  in  the  mouth, 
but,  for  no  reason  whatever,  and  all  unconsciously,  the  fingers  are  with 
great  frequency  raised  to  the  lips  or  the  nose.  Who  can  doubt  that  if 
the  salivary  glands  secreted  indigo  the  fingers  would  not  continually  be 
stained  a  deep  blue,  and  who  can  doubt  that  if  the  nasal  and  oral  secre- 
tions contain  the  germs  of  disease  these  germs  will  not  be  almost  as  con- 
stantly found  upon  the  fingers?  All  successful  commerce  is  reciprocal, 
and  in  this  universal  trade  in  human  saliva  the  fingers  not  only  bring 
foreign  secretions  to  the  mouth  of  their  owner,  but  there,  exchanging  it 
for  his  own,  distribute  the  latter  to  everything  that  the  hand  touches. 
This  happens  not  once,  but  scores  and  hundreds  of  times  during  the  day's 
round  of  the  individual.  The  cook  spreads  his  saliva  on  the  muffins  and 
rolls,  the  waitress  infects  the  glasses  and  spoons,  the  moistened  fingers  of 
the  peddler  arrange  his  fruit,  the  thumb  of  the  milkman  is  in  his  measure, 
the  reader  moistens  the  pages  of  his  book,  the  conductor  his  transfer 
tickets,  the  'lady'  the  fingers  of  her  glove.  Everyone  is  busily  engaged 
ill  this  distribution  of  saliva,  so  that  the  end  of  each  day  finds  this  secre- 
tion freely  distributed  on  the  doors,  window  sills,  furniture,  and  play- 
things in  the  home,  the  straps  of  trolley  cars,  the  rails  and  counters  and 
desks  of  shops  and  public  buildings,  and,  indeed,  upon  everything  that 
the  hands  of  man  touch.  What  avails  it  if  the  pathogens  do  die  quickly  ? 
A  fresh  supply  is  furnished  each  day.  Besides  the  moistening  of  the 
fingers  with  saliva  and  the  use  of  the  common  drinking  cup,  the  mouth 
is  put  to  numberless  improper  uses  which  may  result  in  the  spread  of 


162      DISEASES   SPEEAD   THEOUGH   MOUTH   AND   NOSE 

infection.  It  is  used  to  hold  pins,  string,  i)ei)cils,  i)apcr,  and  money. 
The  lips  are  used  to  moisten  the  pencil,  to  point  the  thread  for  the  needle, 
to  wet  postage  stamps  and  envelopes.  Children  'swap'  apples,  cake,  and 
lollipops,  while  men  exchange  their  pipes  and  women  their  hatpins. 
Sometimes  the  mother  is  seen  'cleansing'  the  face  of  her  child  with  her 
saliva-moistened  handkerchief,  and  perhaps  tlie  visitor  is  shortly  after 
invited  to  kiss  the  little  one. 

"Children  have  no  instinct  of  cleanliness,  and  their  faces,  hands,  toys, 
clothing,  and  everything  that  they  touch  must  of  necessity  be  continually 
daubed  with  the  secretions  of  the  nose  and  mouth.  It  is  well  known  that 
children  between  the  ages  of  two  and  eight  years  are  more  susceptible  to 
scarlet  fever,  diphtheria,  measles,  and  whooping-cough  than  at  other 
ages,  and  it  may  be  that  one  reason  for  this  is  the  great  opportunity  that 
is  afforded  by  their  habits  at  these  ages  for  the  transfer  of  the  secretions. 
Infants  do  not,  of  course,  mingle  freely  with  one  another,  and  older  chil- 
dren do  not  come  in  close  contact  in  their  play,  and  they  also  begin  to 
have  a  little  idea  of  cleanliness." 

Milk-borne  Diphtheria. — The  diphtheria  bacillus  grows  well  in  milk 
without  appreciably  changing  its  flavor  or  appearance.  Trask  collected 
33  diphtheria  epidemics' from  the  literature  between  1895  and  1907.  Fif- 
teen of  these  occurred  in  the  United  States  and  8  in  Great  Britain.  The 
milk  is  usually  contaminated  by  cases  of  the  disease  occurring  on  the 
farm  or  at  the  dairy  or  milk  shop.  In  some  cases  the  diseased  person 
milks  the  cows  or  the  same  person  nurses  the  sick  and  handles  the  milk. 
In  two  instances  the  outbreak  was  supposed  to  be  due  to  disease  of  the 
cow.  One  instance  studied  by  Dean  and  Todd  is  instructive.  In  certain 
families  supplied  with  milk  from  two  cows  there  occurred  two  cases  of 
clinically  typical  diphtheria  and  three  of  sore  throat,  whereas  in  another 
family  using  the  milk,  only  after  sterilization,  no  case  occurred.  One  of 
the  cows  had  mammitis  and  furnished  a  scanty,  ropy,  semi-purulent,  and 
slightly  blood-tinged  milk.  The  Klebs-Loffler  bacilli  were  isolated  in  all 
cases  and  also  from  the  milk  of  the  cow  with  mammitis.  Experiments 
justified  the  conclusion  that  the  ulcers  upon  the  udder  of  the  cow  with 
mammitis  had  become  secondarily  infected  with  B.  di-plitlieriae,  acci- 
dentally from  some  apparently  healthy  person. 

Bacillus  Carriers. — It  was  in  the  case  of  diphtheria  that  the  danger 
of  bacillus  carriers  was  first  realized.  It  is  now  known  that  persons  who 
come  in  contact  with  diphtheria  patients  are  very  apt  to  harbor  diph- 
theria bacilli,  though  they  may  remain  in  good  health.  It  is  also  now 
well  known  that  a  certain  percentage  of  the  population  at  large  harbor 
the  diphtheria  bacilli  in  their  nose  or  throat,  even  though  they  have  had 
no  known  association  with  the  disease.  Graham-Smith  found  that  dQ 
per  cent,  of  the  members  of  the  family  to  which  the  diseased  person 
belonged  were  in|ected;  the  proportion  being  higher  (100  to  50  per  cent.) 


DIPHTHERIA  163 

in  families  in  which  no  precautions  were  taken  to  isolate  the  sick,  and 
much  lower  (10  per  cent.)  when  such  precautions  were  taken.  Of  the 
more  distant  relatives  examined,  29  per  cent,  were  found  to  be  carriers. 
Bacilli  were  found  in  37  per  cent,  of  persons  in  attendance  on  the  sick. 
Observations  of  the  inmates  of  hospital  wards  and  institutions  showed 
that  14  per  cent,  are  likely  to  give  positive  cultures  when  diphtheria 
occurs  among  them.  In  infected  schools  8.7  per  cent,  of  the  scholars 
were  found  to  be  bacillus  carriers".  In  New  York,  Scholley  examined 
1,000  children  from  the  tenement  districts,  and  found  18  with  virulent 
and  38  with  non- virulent  bacilli.  Moss,  Guthrie  and  Gelien  found  B. 
diphtheriae  in  3.61  per  cent,  of  1,217  school  children  in  Baltimore,  and 
3.48  per  cent,  of  1,290  individuals  in  the  city  at  large.  Slack,  Arms, 
Wade,  and  Blanchard  took  cultures  at  the  beginning  of  the  school  year 
from  about  4,500  pupils  in  the  Brighton  district,  Boston.  Diphtheria 
was  not  prevailing  at  the  time.  Nevertheless,  at  least  1  per  cent,  of  all 
these  healthy  school  children  were  found  to  carry  morphological  typical 
diphtheria  bacilli.  It  is  estimated  that  this  is  the  average  ratio  in  the 
population  at  large. 

Ordinarily  the  bacilli  found  in  diphtheria  carriers  under  such  cir- 
cumstances have  little  or  no  virulence.  It  is  exceedingly  unlikely  that 
the  virulence  of  such  strains  may  be  raised  by  passing  through  a 
susceptible  individual.  It  is  probable,  however,  that  diphtheria  is  kept 
alive  in  a  community  rather  by  the  virulent  organisms  in  immune  persons 
than  by  these  non-virulent  strains.  None  of  the  children  in  the  Brighton 
district  above  mentioned  had  any  known  association  with  the  disease,  nor 
did  they  afterward  develop  diphtheria.  The  danger  of  such  carriers  is, 
therefore,  problematic,  and,  on  account  of  their  large  number,  it  is  a 
question  whether  they  should  be  isolated.  The  dangerous  carrier  is  he 
who  harbors  the  virulent  strain,  and  this  is  usually  obtained  from  the 
patient,  convalescent,  or  from  a  third  person  who  has  come  in  contact 
with  the  patient.  From  our  present  standpoint  it  seems  impractical  to 
stamp  out  diphtheria  from  a  large  city  by  cultural  tests  of  all  its  inhab- 
itants and  isolation  of  all  carriers,  especially  where  dependence  is  placed 
upon  morphological  diagnosis.  Some  harmless  bacteria  have  the  morpho- 
logical appearance  of  the  diphtheria  bacillus.  The  virulent  bacilli  may  be 
differentiated  from  the  avirulent  strains  by  injecting  pure  cultures  into 
guinea-pigs.  Zingher  and  Soletsky  ^  have  improved  Neisser's  method  by 
using  2  guinea-pigs  for  the  testing  of  from  4  to  6  different  strains.  One 
guinea-pig  serves  as  a  control  and  receives  about  200  units  of  antitoxin 
intracardially  at  the  time  of  making  the  test,  or  intraperitoneally  24 
hours  before.  Both  pigs  are  injected  with  suspensions  of  the  cultures  to 
be  tested  intracutaneously.     A  fresh  24-hour  growth  from  an  ordinary 

^Zingher  and  Soletsky:  Proceedings  of  the  New  York  Pathological  Society, 
N.  S.,  Vol.  XV,  Nos.  1  and  2,  January  and  February,  1915. 


164     DISEASES   SPEEAD   THKOUUH   MOUTH    AM)    NOSK 

Loffler  slant  is  suspended  in  25  to  ;W)  c.  c.  oC  normal  nail  .-dliilicjii ;  0.10 
('.  c.  is  injected  into  the  skin.  'I'lic  I'csult.s  of  llio  t(,'sls  an-  noted  in  24 
to  48  hours.  Virulent  strains  produce  a  definite  l(j<-al  iidlaniinatory 
lesion,  which  shows  a  superlicial  necrosis  in  4<S  to  72  hours,  in  the  con- 
trol pig  the  skin  remains  normal.  With  non-virulent  strain,-  no  lesiojis 
will  be  found  in  either  control  or  test  animal.  It  is  phiin  that  the 
control  of  diphtheria  outbreaks  in  institutions,  camjjs,  on  sliiphoard, 
schools,  and  in  similar  places,  where  a  number  oC  people  arc  crowded 
together,  as  well  as  the  final  control  of  epidemic  (nithreaks  in  cities  and 
towns,  depends  eventually  upon  the  recognition  of  carriei's  and  their 
isolation. 

The  length  of  time  it  requires  for  diphtheria  bacilli  to  disappear  fnnn 
the  throat  and  nose  varies  greatly.  Beebe  and  Park  found  that  in  304 
of  605  consecutive  cases  the  bacilli  disappeared  within  3  days  after  the 
disappearance  of  the  false  membrane.  In  176  cases  they  persisted  for  7 
days,  in  64  cases  for  12  days,  in  36  for  15  days,  in  12  cases  for  3  weeks, 
in  4  cases  for  4  weeks,  and  in  2  cases  for  9  weeks.  In  some  instances  the 
virulent  organisms  may  remain  for  months. 

Diphtheria  bacilli  disappear  in  about  50  per  cent,  of  cases  by  the  time 
the  local  membrane  has  disappeared.  The  bacilli  persist  in  about  5  per 
cent,  of  persons  at  the  end  of  two  months,  about  2  per  cent,  at  the  end 
of  3  months,  and  approximately  1  per  cent,  continue  as  chronic  bacillus 
carriers.  Of  the  general  population  who  have  not  been  affected  by  the 
disease  1  or  2  per  cent,  are  carriers  under  ordinary  circumstances,  and 
from  5  to  10  per  cent,  during  epidemics  of  the  disease.  These  figures 
include  both  virulent  and  avirulent  forms.  It  is  now  believed  that  the 
carriers  of  avirulent  bacilli  are  harmless.  The  virulence  of  the  diph- 
theria bacilli  seems  to  be  but  slightly  lessened  during  the  carrier  con- 
dition. 

Many  methods  have  been  used  to  cure  diphtheria  carriers.  These 
consist  of  liquid  antiseptics  applied  as  swabs,  sprays  or  gargles;  the 
inhalation  of  antiseptic  vapors;  the  use  of  diphtheria  vaccin,  toxin,  anti- 
toxin, and  antibacillary  serum;  also  toxins  of  the  BaciUus  pyocyaneus, 
and  the  introduction  of  cultures  of  staphylococci,  yeast  and  other  micro- 
organisms. Hektoen  and  Eappaport  ^  obtained  results  by  the  use  of  kao- 
lin.   Good  results  have  followed  and  failed  in  all  the  methods  so  far  tried. 

The  diphtheria  bacilli  probably  do  not  long  persist  upon  normal 
mucous  membranes,  but  continue  in  pockets,  folds,  crypts  of  the  tonsils, 
fissures  of  adenoids,  spaces  about  the  turbinates,  the  sinuses  connected 
with  the  nasal  cavity,  and  in  any  irritated,  inflamed  or  ulcerated  portion 
of  the  mucous  membrane.  Therefore,  the  removal  of  enlarged  tonsils, 
polypi,  foreign  bodies,  and  other  sources  of  irritation  and  inflammation 

^Albert,  Henrv:  "The  Treatment  of  Diphtheria  Carriers."  J.  A.  U..  M„ 
Scj)l.  27,   ID  1.3.  LXI.   l:i.  ]).  1027. 


DirHTHERTA  105 

has  resulted  in  the  cure  of  diphtheria  carriers.  The  first  indication  is 
to  treat  the  mucous  membrane  of  the  upper  respiratory  passages  so  as  to 
get  it  in  a  normal  condition.  Albert  ^  recommends  the  application  of 
silver  nitrate  to  the  crypts  of  the  tonsils. 

The  disappearance  of  the  bacilli  from  the  throat  and  nose  cannot  be 
hastened  by  the  usual  injections  of  antitoxin.  Diphtheria  antitoxin,  when 
injected  subcutaneously,  protects  the  individual  but  does  not  harm  the 
bacilli.  A  serum  containing  agglutinins  has  been  used.  This  serum  in 
powdered  form  is  blown  into  the  throat.  The  diphtheria  bacilli  are  sup- 
posedly agglutinated  and  may  then  be  more  readily  washed  away  by 
gargling  and  douching.  A  substance  proposed  by  Emmerich  known  as 
"pyocyanase"  has  been  used.  This  contains  a  ferment  from  bouillon  cul- 
tures of  the  Bacillus  pyocyaneus.  It  is  applied  locally  and  acts  by  its 
power  of  bacteriolysis. 

Encouraging  results  have  recently  been  reported  by  "over-riding"  the 
throats  of  diphtheria  carriers  with  suspensions  of  Staphylococcus  pyo- 
genes aureus,  which  are  sprayed  into  the  throat  and  nose.  The  method 
was  introduced  by  Schiotz  in  1909,  who  reported  the  prompt  disappear- 
ance of  diphtheria  bacilli  in  six  carriers.  Page,  also  Catlin,  Scott  and 
Day,  Lorenz  and  Eavenel,  and  others,  have  reported  successful  results. 

Hewlett  and  Nankivell,  and  also  Petrusehky,  report  encouraging 
results  in  clearing  up  diphtheria  carriers  by  the  subcutaneous  injection 
of  a  diphtheria  vaccine. 

AVe  must  acknowledge  that  all  these  measures  often  fail.  The  relief  of 
bacillus  carriers  is  one  of  the  rewardful  problems  in  preventive  medicine. 

Resistance. — The  diphtheria  bacillus  has  less  resistance  to  adverse 
conditions  than  the  majority  of  the  spore-free  bacteria.  It  is  more  read- 
ily destroyed  by  light,  heat,  and  disinfecting  substances  than  the  typhoid 
bacillus.  In  this  regard  it  corresponds  more  to  the  frailer  streptococci. 
Under  certain  circumstances  the  diphtheria  bacillus  resists  drying  for  a 
long  time.  When  enclosed  in  the  false  membrane  or  other  albuminous 
substances,  they  may  remain  virulent  for  some  months. 

Immunity. — Immunity  to  diphtheria  is  an  antitoxic  immunity  and 
persists  for  some  months  or  years  following  a  natural  attack  of  the  dis- 
ease. Occasionally  immunity  is  of  short  duration,  for  second  and  third 
attacks  are  not  uncommon.  Eeiche  ^  states  that  5.8  per  cent,  of  4,761 
cases  of  diphtheria  iii  Hamburg  were  known  to  have  had  a  previous 
attack.  He  presents  further  data  to  confirm  the  absence  of  any  lasting 
immunization  by  a  single  attack  of  diphtheria.  Graef  and  Ginsberg  ^ 
have  shown  by  the  Schick  Reaction  that  immunity  obtained  by  having 

Vow.  A.  M.  A.,  LXIV,  24,  June  12.  1915,  p.  1991. 

-  Reiche,  F.  Reinfection  with  Diphtheria.  Med.  Klin.,  Berlin,  Oct.  12,  IX,  No. 
41,  pp.   1663-1708. 

"Jour.  A.   M.  A.,  LXIV,   1915.  p.   1205. 


1G()     DISEASES   SPREAD   'I'll ROUGH   MOUTH   AND   NOSE 

the  disease  or  the  use  of  immunizing  doses  of  antitoxin  lasts  from  a 
month  to  several  years,  varying  greatly  in  different  individuals,  and  being 
very  brief  in  children.  The  fact  that  healthy  persons  may  harbor  virulent 
bacilli  upon  their  mucous  membrane  for  a  long  time  without  contracting 
the  disease  shows  the  high  grade  immunity  enjoyed  by  many  individuals, 
due  to  antitoxin  in  the  blood.  Persons  vary  markedly  in  susceptibility. 
During  the  first  6  months  of  life  there  is  but  little  susceptibility.  Chil- 
dren between  the  ages  of  3  and  10  are  most  susceptible;  after  that  age 
the  susceptibility  again  decreases.  It  is  known  that  guinea-pigs  born  of 
immunized  mothers  inherit  a  certain  degree  of  resistance,  which  may 
explain  the  relative  insusceptibility  of  children  under  6  months.  This 
may  also  be  accounted  for  by  the  diminished  danger  of  exposure  of  babies 
during  this  age,  especially  in  those  that  are  breast-fed.  Mother's  milk, 
even  colostrum,  contains  protective  antibodies,  which  are  absorbed  by 
the  infant,  and  thus  may  protect  it. 

The  Schick  Reaction. — The  presence  or  absence  of  immunity  in  any 
individual  may  readily  be  determined  by  the  Schick  test,  which  tells 
whether  antitoxin  is  present  or  absent  in  the  blood  of  that  individual. 
The  Schick  Eeaction  is  made  by  injecting  into  the  skin  l/50th  of  a  min- 
imum lethal  dose  of  diphtheria  toxin  for  a  250-gram  guinea-pig.  A 
positive  reaction  at  the  site  of  the  injection  means  absence  of  antitoxin, 
that  is,  a  susceptible  individual.  A  negative  reaction  means  the  presence 
of  antitoxin,  hence  immunity.  A  positive  reaction  consists  of  a  reddened 
area  with  a  white  center  at  the  site  where  the  toxin  was  injected  into 
the  skin. 

A  positive  Schick  reaction  is  sufficiently  delicate  to  indicate  less  than 
l/30th  of  a  unit  of  antitoxin  in  1  c.  c.  of  blood  serum.  Such  persons 
are  susceptible  to  diphtheria. 

We  therefore  possess  a  ready  method  of  determining  who  is  sus- 
ceptible and  who  is  naturally  immune.  Persons  Avho  react  negatively  to 
the  Schick  test  will  not  develop  diphtheria.  Therefore  when  an  epidemic 
breaks  out,  such  persons  need  not  be  treated  with  prophylactic  doses  of 
diphtheria  antitoxin. 

The  Schick  test  has  shown  a  striking  similarity  in  reactions  in  fam- 
ilies. If  the  youngest  child  of  a  family  has  a  negative  reaction  all  the 
older  children  are  likely  to  be  negative,  and  if  the  older  children  are 
positive  the  young  ones  are  also.  When  variations  are  found,  the  younger 
children  show  the  positive  reaction  (Park).  The  Schick  reaction  may 
be  used  to  differentiate  between  clinically  doubtful  cases  of  diphtheria, 
in  experimental  work,  and  in  the  handling  of  diphtheria  epidemics  in 
institutions,  etc.,  and  it  is  particularly  applicable  as  a  preliminary 
measure  for  all  persons  who  have  been  exposed  to  diphtheria. 

It  has  been  demonstrated  that  93  per  cent,  of  new-born  infants  have 
antitoxin  in  their  blood.    At  1  year  only  57  per  cent,  of  these  children 


DIPHTHERIA  167 

remain  immune;  50  per  cent,  of  those  between  5  and  15 ;  and  76  per  cent, 
of  those  between  21  and  40.  The  above  figures  obtained  through  the  Schick 
Reaction  correspond  very  closely  to  the  age  distribution  of  the  disease. 

Prevention. — Control  of  Outbreaks  in  Institutions. — Diphtheria 
frequently  appears  in  asylums,  hospitals,  jails,  on  shipboard,  and  similar 
places.  Under  these  conditions  of  crowding  the  disease  has  a  highly 
contagious  tendency.  It  may,  however,  be  controlled  with  every  assur- 
ance of  success  by  the  application  of  well-tried  measures. 

The  most  important  measure  to  suppress  diphtheria  in  an  institution 
is  to  isolate  all  cases  and  all  carriers.  This  is  possible  in  an  institution, 
although  not  very  practical  among  the  population  at  large.  The  isolation 
of  both  cases  and  carriers  is  the  most  important  and  radical  of  our  pre- 
ventive measures.  In  the  case  of  institutions,  jails,  ships,  and  similar 
places  all  those  who  show  cultures  containing  organisms  which  morpho- 
logically resemble  the  diphtheria  bacillus  should  be  isolated,  whether  the 
strains  are  virulent  or  not. 

The  bacilli  frequently  grow  in  the  mucous  membrane  of  the  nose  and 
nasal  pharynx  without  symptoms  indicating  their  localization.  Unless 
cultures  are  taken  from  the  nose,  many  carriers  will  be  overlooked,  leav- 
ing a  large  loophole  in  our  preventive  measures.  Ward  and  Henderson 
in  a  public  school  epidemic  in  Berkeley  in  1907  found  that  all  attempts 
to  isolate  infected  children  had  no  effect  on  the  epidemic  so  long  as  they 
made  throat  cultures  alone.  When  they  took  both  nose  and  throat  cul- 
tures and  quarantined  all  the  children  showing  positive  cultures,  the 
epidemic  stopped. 

Convalescents  should  not  be  released  from  quarantine  until  at  least 
two  cultures  taken  from  both  the  nose  and  throat  are  negative. 

All  persons  within  the  institution,  including  both  inmates  and  ad- 
ministrative force,  should  then  be  tested  to  the  Schick  Reaction.  Those 
reacting  positively  should  be  given  a  prophylactic  dose  of  diphtheria  anti- 
toxin. This,  however,  must  be  regarded  more  as  a  measure  of  temporary 
personal  protection  than  as  a  radical  means  of  stamping  out  the  infection. 
It  is  not  possible  by  the  use  of  diphtheria  antitoxin  alone  to  wipe  out 
diphtheria.  The  bacilli  remain  in  the  throats  of  the  immunized  and 
the  disease  continues  to  crop  out  after  the  antitoxic  immunity  has 
passed  away,  which  may  be  a  matter  of  only  a  few  weeks.  When  diph- 
theria antitoxin  is  used  as  a  prophylactic,  the  customary  dose  is  1,000 
units.  Schick  recommends  50  units  per  kilogram  of  body  weight.  The 
immunizing  dose  may  be  repeated  every  10  days  or  two  weeks  as  long  as 
the  danger  persists. 

Those  who  react  positively  to  the  Schick  Test  may  be  immunized 
with  a  toxin-antitoxin  mixture.^     Each  cubic  centimeter  of  the  mixture 

^Von  Behring:  Deutsche  med.  Wochenschr.,  1913,  XXXIX,  873.  Park  and 
Zingher:    J.  A.  M.  A.,  Dec.  25,  1915,  LXV,  26,  p.  2216. 


1G8      DISEASES    SPKEAD   THKOU(MI    MOUTH    AND    NOSK 

contains  from  80  to  90  per  cent,  of  tlie  L  -(-  dose  of  toxin,  and  one  unit 
of  antitoxin.  One  cubic  centimeter  of  this  mixture  is  injected  subcu- 
taneously  and  repeated  three  times  at  intervals  of  six  or  eight  days.  'J'he 
results  as  determined  by  the  Schick  Eeaction  produce  an  immunity  in 
about  35  to  30  per. cent,  of  injected  individuals  within  four  weeks;  the 
remainder  react  slowly,  in  four  months  to  two  years. 

In  addition  to  the  above-mentioned  measures,  care  must  be  taken  tli;it 
the  infection  is  not  spread  by  the  use  of  cups,  spoons,  dishes,  toys,  towels, 
handkerchiefs,  and  other  articles  used  in  common.  The  infected  dis- 
charges should  be  rendered  harmless  at  the  bedside,  and  all  objects  that 
come  in  contact  with  the  discharges  from  patients  or  carriers  should  be 
disinfected.  A  general  fumigation  with  formaldehyd  may  be  practiced, 
but  in  a  well-ordered  institution  special  cleanliness  of  floors,  walls,  and 
other  surfaces  will  suffice. 

Control  of  Epidemics. — The  principles  which  guide  us  for  the  con- 
trol of  outbreaks  among  the  population  at  large  are  precisely  the  same 
as  those  described  for  the  control  of  epidemics  in  institutions.  The  only 
difference  is  that  in  the  population  at  large  it  is  more  difficult,  if  not 
impossible,  to  apply  the  one  real  important  measure,  namely,  that  of 
isolating  the  carriers. 

In  certain  complex  situations  in  cities,  the  free  and  general  use  of 
antitoxin  will  help  check  an  outbreak  of  diphtheria  by  reducing  the 
number  of  clinical  cases. 

Schools  need  not  be  closed  during  an  epidemic  of  diphtheria;  in  fact, 
better  results  will  be  achieved  by  daily  inspection  and  examination  of  cul- 
tures from  the  nose  and  throat  of  each  pupil.  The  well  children  of  a 
household,  where  a  person  is  ill  with  diphtheria,  should  be  excluded  from 
school  until  one  week  has  expired  from  the  date  of  the  last  exposure, 
unless  showing  two  negation  cultures  from  throat  and  nose.  All  other 
members  of  the  household  may  be  allowed  to  continue  their  usual  occu- 
pations, except  those  who  are  engaged  in  the  handling  of  milk. 

In  almost  all  communities  diphtheria  is  now  one  of  the  diseases  which 
must  be  reported  to  the  health  authorities.  The  houses  are  placarded 
and  the  cases  isolated.  There  is  no  great  objection  to  treating  a  case  of 
diphtheria  in  the  household  provided  the  patient  and  the  nurse  may  also 
be  quarantined  from  the  rest  of  the  household.  Under  these  circum- 
stances and  with  intelligent  care  and  disinfection  at  the  bedside  there  is 
little  danger  to  the  rest  of  the  family;  but  the  great  menace  that  some 
of  the  members  of  the  family  will  become  bacillus  carriers  of  a  dangerous 
type  makes  it  advisable  to  treat  all  cases  of  diphtheria  in  a  special  hos- 
pital. 

The  prompt  and  early  diagnosis  of  diphtheria  has  now  become  one  of 
the  routine  measures  of  board  of  health  laboratories.  This  example  in  the 
case  of  diphtheria  could  be  extended  with  advantage  to  the  other  com- 


DIPHTHERIA  169 

miinicable  diseases  for  which  we  have  satisfactory  laboratory  aids.  Espe- 
cially commendable  is  the  general  practice  of  refusing  to  lift  the  quaran- 
tine until  two  successive  cultures  prove  negative. 

Disinfection  in  diphtheria  should  be  applied  especially  to  the  secre- 
tions from  the  mouth  and  nose.  These  may  be  received  upon  a  piece  of 
gauze  and  burned.  For  the  hands  and  other  objects  bichlorid  of  mercury 
(1-1,000),  carbolic  (2i/2  per  cent.),  formalin  (10  per  cent.),  cresol  prep- 
arations (1  per  cent.),  are  efficient.  As  a  terminal  disinfectant  formal- 
dehyd  gas  may  be  used,  but  the  ordinary  fumigation,  as  practiced  by 
Boards  of  Health,  seems  to  have  little  influence  in  cheeking  the  spread  of 
the  disease.  Evidence  is  accumulating  that  the  infection  usually  comes 
from  persons  rather  than  from  things.  Bed  linen,  towels,  and  other 
fabrics  should  be  boiled  or  steamed. 

Personal  Prophylaxis. — In  individual  cases  diphtheria  may  be 
avoided  by  the  use  of  diphtheria  antitoxin.  The  antitoxic  immunity, 
however,  depends  upon  the  free  circulation  of  the  antibodies  in  the  blood, 
and  as  the  antitoxin  is  gradually  eliminated  it  cannot  be  depended  upon 
to  protect  more  than  2  or  3  weeks.  Those  who  react  negatively  to 
the  Schick  reaction  will  not  contract  the  disease,  but  may  become 
carriers. 

Diphtheria  antitoxin  is  a  specific  and  sovereign  remedy.  When  given 
in  sufficient  amounts  during  the  first  2-t  hours  of  the  disease  it  reduces 
the  mortality  to  practically  nil.  Ordinarily  500  units  are  sufficient  for 
prophylactic  purposes,  but  1,000  units  are  preferable,  as  this  amount 
produces  an  immunity  of  higher  degree  and  longer  duration.  When  the 
exposure  to  the  infection  continues  the  antitoxin  may  be  administered 
at  successive  intervals  of  about  2  or  3  weeks.  Upon  the  first  appearance 
of  sore  throat,  fever,  or  other  suggestive  symptoms  in  persons  who  are 
exposed  to  diphtheria  a  full  dose  of  3,000  to  10,000  units  should  be 
administered  without  delay.  Shick  recommends  500  units  per  kilogram 
of  body  weight  given  intramuscularly.  In  order  to  obtain  the  full  life- 
saving  benefits  of  diphtheria  antitoxin,  it  should  be  given  early  in  the 
disease.  Time  is  the  most  important  factor.  When  the  damage  to  the 
cells  has  been  done,  it  may  be  too  late.  It  is  not  always  advisable  to 
wait  for  bacterial  confirmation. 

People  still  die  of  diphtheria  because  antitoxin  is  not  given  in  time. 
The  disease  often  begins  insidiously  and  the  true  diagnosis  is  often  not 
made  until  too  late  for  antitoxin  to  exert  its  life-saving  power — this  is 
prone  to  occur  in  physician's  families. 

Personal  prophylaxis  is  further  favored  by  the  individual  having  his 
own  glass,  cups,  spoons,  towels,  etc.,  and  exercising  personal  cleanliness, 
especially  concerning  the  hands  and  all  objects  placed  in  the  mouth. 
Physicians,  nurses,  and  others  who  come  in  close  contact  with  the  patient 
should  guard  against  droplet  infection. 


170     DISEASES    SPREAD   THROUGH   MOUTH   AND   NOSE 

PREVENTION  OF  POSTDIPHTHERITIC  PARALYSIS 

It  has  been  observed  that  postdiphtheritic  paralysis  is  more  fre- 
quent since  the  use  of  antitoxin  than  before  the  days  of  serum  therapy. 
This  is  due  to  the  fact  that  many  cases  now  recover  that  would  for- 
merly have  died.  It  is  also  due  to  the  fact  that  diphtheria  antitoxin 
is  sometimes  used  too  late^  thus  neutralizing  only  the  acute  effects  of 
the  toxin,  but  not  neutralizing  the  after-effects  of  the  toxon  which 
acts  specifically  upon  the  nerves.  The  prevention  of  postdiphtheritic 
paralysis,  therefore,  consists  in  giving  sufficient  amounts  of  antitoxin 
early  in  the  disease.  The  antitoxin  does  not  influence  the  paralysis 
after  it  has  once  appeared. 

PRETENTION  OF  SERUM  SICKNESS 

This  subject  may  appropriately  be  considered  here,  although  it  is 
a  condition  that  may  follow  the  injection  of  any  alien  serum  into 
the  system.  Serum  sickness  is  a  syndrome  which  frequently  follows 
the  injection  of  horse  serum  into  man.  The  symptoms  come  on  after 
about  8  or  10  days  following  the  injection.  They  consist  of  various  skin 
eruptions,  usually  urticarial  or  erythematous  in  character;  also  fever, 
edema,  glandular  enlargements,  rheumatic-like  pains  in  the  joints, 
and  albuminuria.  The  eruptions  may  be  either  local  or  general,  and 
sometimes  resemble  those  of  scarlet  fever  or  measles.  Serum  sickness 
has  nothing  to  do  with  the  antitoxin,  but  is  caused  entirely  by  the 
foreign  proteins  contained  in  the  horse  serum.  It  may  be  produced 
with  normal  horse  serum  as  well  as  with  antitoxic  horse  serum.  The 
studies  upon  anaphylaxis  have  thrown  much  light  upon  the  nature  of 
this  complication.  The  serum  of  some  horses  is  said  to  be  more  apt  to 
produce  the  syndrome  than  that  of  other  horses.  A  serum  that  is  sev- 
eral years  old  is  perhaps  less  apt  to  produce  these  reactions  than  a 
fresh  serum.  Manufacturers  of  antitoxin,  therefore,  prefer  to  keep 
their  serum  in  the  ice  chest  some  time  before  they  place  it  upon  the 
market,  although  this  is  a  doubtful  expedient.  The  occurrence  and  se- 
verity of  the  symptoms  are  in  direct  proportion  to  the  amount  of  foreign 
protein  injected  and  the  sensitiveness  of  the  individual.  Fortunately, 
this  form  of  anaphylactic  reaction  soon  passes  away  and  is  never  serious. 
Under  certain  circumstances,  however,  there  may  be  an  accelerated  or 
immediate  reaction  threatening  in  its  consequence  or  even  leading  to 
death.  Rosenau  and  Anderson  have  collected  some  19  cases  of  sudden 
death  following  the  injection  of  horse  serum,  and  they  know  of  more  in- 
stances which  have  not  appeared  in  the  literature.  This  unusual  and 
serious  complication  comes  on  within  5  or  10  minutes  of  the  injection. 


DIPHTHEEIA  171 

and  is  characterized  by  collapse,  unconsciousness,  cyanosis,  labored  respi- 
ration, and  edema.  The  heart  continues  to  beat  after  respiration  has 
ceased.  The  entire  picture  is  an  exact  counterpart  of  the  anaphylactic 
shock  so  readily  reproduced  by  a  second  injection  of  horse  serum  or  other 
foreign  protein  in  the  guinea-pig.  Contrary  to  the  experimental  work 
on  the  lower  animals,  most  of  the  cases  of  sudden  death  in  man  follow  the 
first  injection  of  horse  serum.  The  serious  symptoms  and  death  in  these 
cases  are  not  due  to  any  inherent  poisonous  property  in  the  antitoxic 
serum,  but  result  entirely  from  a  hypersusceptibility  of  the  individual. 
Just  how  man  becomes  sensitized  in  these  cases  is  not  known.  Most  of 
the  cases,  however,  occur  in  asthmatics  or  in  persons  who  gave  a  history 
of  asthma  or  discomfort  when  about  horses.  This  is  a  practical  and  im- 
portant point,  and  should  be  inquired  into  before  horse  serum  of  any 
kind  is  injected.  Horse  serum  should  not  be  injected  into  such  individ- 
uals unless  the  indications  are  clear,  and  then  only  with  a  statement  as 
to  the  possible  outcome. 

In  order  to  prevent  this  serious  complication  a  small  quantity 
may  first  be  injected,  1/20  to  1/50  c.  c,  and  after  waiting  an  hour  the 
remainder  may  be  given.  Vaughan  proposed  0.5  c.  c.  as  the  trial  dose, 
but  this  is  excessive,  as  some  of  the  fatal  cases  have  followed  the  in- 
jection of  about  1  c.  c.  It  is  known  that  in  man,  as  in  the  experi- 
mental cases  in  the  guinea-pig,  the  severity  of  the  symptoms  bears  a 
definite  ratio  to  the  amount  of  serum  and  the  mode  of  injection.  Thus, 
second  injections  in  the  guinea-pig  are  much  more  fatal  when  given 
directly  into  the  circulation  than  into  the  subcutaneous  tissue.  It  is 
sometimes  advisable  to  give  antitoxic  sera  directly  into  the  circula- 
tion, but  in  the  susceptible  persons  under  discussion  this  would  be 
hazardous.     Bovine  antitoxin  may  be  used. 

Friedberger  and  Mita  ^  found  it  possible  to  avoid  all  symptoms  of 
anaphylaxis  in  experimental  work  with  guinea-pigs  by  injecting  the 
serum  extremely  slowly.  When  thus  introduced  animals  are  able  to 
tolerate  an  amount  far  beyond  the  ordinary  lethal  dose. 

Eichholz  -  demonstrated  that  a  suspension  of  desiccated  antitoxic 
serum  in  olive  oil  seems  to  retain  all  the  therapeutic  possibilities  unim- 
paired while  the  serum  is  absorbed  so  much  more  slowly  and  gradually 
that  the  danger  of  anaphylactic  reactions  is  thereby  diminished.  This 
method  cannot  be  used  where  speedy  action  is  wanted,  but  it  may  be 
found  useful  in  prophylaxis  and  in  cases  in  which  there  are  reasons  for 
anticipating  trouble  from  anaphylaxis. 

*  Friedberger,  E.,  and  Mita.  S. :  "To  Prevent  Anaphylaxis  in  Serotlierapy" 
("Methode,  grossere  Mengen  artfremden  Serums  bei  iiberempfindlichen  Individuen 
zu  injizieren"),  Deutsche  med.  Wochenschr.,  Berlin,  Feb.  1,  XXXVIII  No.  5,  pp. 
201-248. 

^Eichholz,  W.:  Desiccated  Antitoxin  and  Serums.  Munchen.  med.  Wchnschr., 
Nov.  18,  LX,  46. 


'l72     DISEASES   SPKEAD   THKOUGH   MOUTH   AX  I)    NOSE 

Chloral,  chloroform,  and  atropiu  in  Cull  therapeutic  amounts  are 
claimed  to  ameliorate  or  even  prevent  anaphylactic  shock,  but  it  must  be 
admitted  that  none  of  the  above  procedures  is  wholly  satisfactory. 

Historical  Note. — A  complete  summary  and  bibliography  of  diph- 
theria up  to  1908  will  be  found  in  the  system  edited  by  Nuttall  and 
Graham-Smith  entitled  "The  Bacteriology  of  Diphtheria,"  containing 
articles  by  Loffler,  Newsholme,  Mallory,  Graham-Smith,  Dean,  Park, 
and  Bolduan;  Cambridge  University  Press,  1908. 

The  original  clinical  description  of  the  disease  is,  by  common  as- 
sent, attributed  to  Bretonneau  in  1S26:  Traite  de  la  diphtherite.  Des 
inflammations  speciales  du  tissu  muqueux  et  en  particulier  de  la  diph- 
therite ou  inflammation  pelliculaire,  connue  sous  le  nom  de  croup,  d"an- 
gine  maligne,  d'angine  gangreneuse,  etc.,  Paris. 

The  bacillus  of  diphtheria  was  first  cultivated  and  adequately  de- 
scribed by  Loffler,  1884 :  Dntersuchungen  fiber  die  Bedeutung  der 
Mikroorganismen  fur  die  Entstehung  der  Diphtheric  beim  Menschen 
bei  der  Taube  und  beim  Kalbe.  MiWi.  a.  d.  K.  Gesundheitsamte,  ii, 
451. 

The  classical  article  in  which  Behring  and  Kitasato  announced 
their  discovery  of  diphtheria  antitoxin  in  1890  will  be  found  in  Deutsche 
med.  Wochenschr.,  xvi,  1113.  TJeber  das  Zustandekommen  der  Diph- 
therieimmunitat  und  die  Tetanusimmunitat  bei  Tieren. 

Ehrlich's  important  work,  in  which  he  laid  the  foundations  of  his 
side-chain  theory  and  established  the  present  satisfactory  method  of 
standardizing  diphtheria  antitoxin,  will  be  found  in  the  following: 
Die  Werthbemessung  des  Diphtherieheilserums  und  deren  theoretische 
Grundlagen.  Klin.  Jahrb.,  Jena,  v,  6  (2),  1897,  pp.  299-326.  Ueber 
die  Constitution  des  Diphtheriegiftes.  Deut.  med.  Wocli.,  Leipzig,  v. 
24  (38),  1898,  pp.  597-600.  Croonian  lecture.  On  Immunity  with 
Special  Eeference  to  Cell  Life.  Proc.  Roy.  Soc,  London,  v,  66,  pp. 
424-448,  pis.  6-7. 

The  official  method  for  standardizing  diphtheria  antitoxin  in  this 
country  and  the  principle  upon  which  it  is  based  are  described  by 
Eosenau  (1905),  The  Immunity  Unit  for  Standardizing  Diphtheria 
Antitoxin  (based  on  Ehrlich's  normal  serum).  Hygienic  Laboratonj 
Bull,  No.  21,  P.  H.  and  M.  H.  S.,  Washington,  Govt.  Print.  Office,  92  pp. 


MEASLES 

Measles  is  usually  taken  as  the  type  of  a  contagious  disease  because 
it  is  one  of  the  most  readily  communicable  of  all  diseases,  in  this  re- 
gard ranking  with  smallpox.  As  a  cause  of  death  it  ranks  high  among 
the  acute  fevers  of  children. 


MEASLES 


173 


In  the  registration  area  of  the  United  States,  during  the  twelve  years 
from  1900-1911,  50,000  deaths  from  measles  were  recorded,  and  it  is 
estimated  that  over  100,000  deaths  were  caused  by  measles  in  the  con- 
tinental United  States  during  the  same  period.  The  number  of  deaths 
from  measles  as  compared  with  those  of  certain  other  diseases  in  the 
registration  area  during  the  year  1910,  is  shown  in  the  following  table: 


Disease 


Deaths. 


Deaths  per 

100,000 
Population 


Diphtheria  and  croup. .  . 

Measles 

Scarlet  fever 

Whooping  cough 

Cerebrospinal  meningitis 
Infantile  paralysis 


11,512 
6,598 
6,255 
6,148 
2,272 
1,459 


21.4 
12.3 
11.6 
11.4 
4.2 
2.7 


Measles  is  an  infection  peculiar  to  man,  although  experimental 
measles  has  recently  been  produced  in  monkeys.  The  virus  is  contained 
in  the  blood,  as  has  been  shown  by  Hektoen,  who  thus  transmitted  the 
disease  from  man  to  man.  More  important  from  the  standpoint  of 
prevention,  the  virus  has  been  demonstrated  in  the  secretions  from  the 
nose  and  mouth  by  Anderson  and  Goldberger.  The  period  of  incubation 
is  quite  constant  (from  9  to  11  days),  and  the  rash  appears  quite  uni- 
formly on  the  13th  or  14th  day  after  the  infection.  In  Hektoen's  two 
experimental  cases  the  eruption  appeared  on  the  14th  day.  The  cause 
of  measles  is  not  known. 

Measles  is  more  or  less  constantly  present  in  all  large  cities  in  the 
temperate  zone;  it  is  less  common  in  the  tropics,  although  it  spreads 
as  readily  in  hot  as  in  cold  climates.  All  races  are  susceptible ;  the  death 
rate  is  higher  in  urban  than  in  rural  districts.^  Measles  frequently 
becomes  epidemic,  usually  in  the  cooler  months,  in  this  respect  resem- 
bling smallpox.  The  epidemics  recur  cyclically,  at  intervals  of  two  or 
three  years.  Levy  and  Foster  noticed  that  in  Eichmond,  Va.,  epidemic 
outbreaks  recurred  at  intervals  of  about  3  years.  They  were  able  to 
predict  and  warn  against  an  epidemic  prevalence  of  the  disease  in  the 
winter  of  1910.  During  1909,  40  cases  of  measles  occurred  in  Eichmond, 
but  during  this  year  the  disease  showed  no  special  tendency  to  spread.  In 
the  middle  of  February,  1910,  8  cases  occurred  among  the  pupils  of  one 
school  and  the  infection  showed  a  high  degree  of  communicability.  Ac- 
cording to  the  history  of  the  disease,  an  epidemic  year  was  due  and  an 
epidemic  was  predicted.  Over  2,000  cases  occurred  with  26  deaths. 
Measles  is  highly  contagious  during  the  preemptive  stage,  when  the 


*Crum,  F.  S. :     A  Statistical  Studv  of  Measles.     Am.  Jour,  of  Puh.  Health, 
April,  1914,  Vol.  IV,  No.  4,  p.  289. 


174      DISEASES   SPREAD   THROUGH   MOUTH   AND   NOSE 

nature  of  the  disease  is  not  recognized  and  wiicn  most  of  the  damage 
is  done;  it  remains  contagious  for  a  variable  time  during  convalescence. 
Recent  experimental  evidence  and  clinical  experience  plainly  indicate 
that  the  infection  of  measles  soon  dies  out,  and  that  there  is  little  danger 
of  transmitting  the  infection  after  the  temperature  returns  to  normal. 
An  isolation  of  two  weeks  from  the  onset  of  the  disease  is  sufficient  in 
public  health  work;  health  officers,  however,  adopt  arbitrary  times. 
Thus,  in  Detroit  cases  of  measles  are  isolated  one  week ;  in  Buffalo,  Con- 
cord, New  York,  Providence,  and  Yonkers,  two  weeks;  in  Brookline  and 
Pall  River,  two  weeks  after  the  eruption  fades;  in  Boston,  two  weeks 
after  recovery ;  and  three  weeks  in  Montclair,  N.  J.,  New  Bedford,  Mass., 
Ottumwa,  Iowa.  For  public  health  purposes  the  maximum  period  of 
incubation  is  placed  at  14  days. 

Immunity. — One  attack  of  measles  usually  confers  a  definite  protec- 
tion against  subsequent  attacks;  second  attacks,  however,  are  more  com- 
monly reported  than  in  the  other  eruptive  fevers.  Some  persons  are  said 
to  have  the  disease  three  or  four  times.  The  close  similarity  between 
rubella  (German  measles)  and  rubeola  (measles)  accoimts  for  many  so- 
called  second  attacks  of  measles.  As  with  smallpox,  there  appears  to  be 
no  natural  immunity  to  measles — man  is  exquisitely  susceptible  to  these 
two  infections.  There  appears  to  be  a  relative  immunity  sometimes  of 
a  high  grade  during  the  first  few  months  of  life,  although  measles  oc- 
casionally occurs  in  infants  of  a  month  or  six  weeks. 

Adults  are  susceptible  to  measles,  provided  they  have  not  had  a 
previous  attack.  Susceptibility  to  the  infection  does  not  diminish  with 
increasing  age;  the  disease  is  apparently  one  of  childhood  only  on  ac- 
count of  the  chances  of  exposure  in  early  life.  Before  the  days  of  vac- 
cination smallpox  was  also  a  disease  mainly  of  childhood. 

The  following  instances  demonstrate  the  susceptibility  of  adults  to 
measles  and  also  the  serious  nature  of  the  disease:  Measles  was  intro- 
duced into  the  Faroe  Islands  in  1846  from  Copenhagen,  and  over  6,000 
of  the  7,782  inhabitants  were  stricken.  In  1775  it  was  introduced  into 
the  Sandwich  Islands,  and  in  4  months  40,000  of  the  population  of 
150,000  died.  In  1874,  Thacombau,  the  native  chief  of  the  Fiji  Islands, 
had  measles  while  on  a  visit  to  Sydney.  His  son  and  a  native  attendant 
sickened  on  the  voyage  home,  and  carried  the  infection  to  the  islands, 
with  the  result  that  one-fifth  of  the  population  (20,000)  died. 

Measles  is  common  in  army  camps,  especially  among  troops  enlisted 
from  country  districts,  who  are  thus  exposed  to  the  infection  for  the 
first  time. 

]\Ieasles  is  often  fatal  both  in  adults  and  children  on  account  of 
pneumonic  complications.  It  lowers  the  resistance  to  tuberculosis  and 
noma;  it  is  a  common  history  to  find  tuberculosis  develop  in  children 
following  an  attack  of  measles. 


MEASLES  175 

Resistance  of  the  Virus. — In  general  the  virus  of  measles  is  known 
to  be  much  less  resistant  than  that  of  scarlet  fever  and  many  other  in- 
fections. The  virus  does  not  live  long  upon  fomites.  There  is  prac- 
tically no  danger  of  children  contracting  the  infection  from  the  room 
in  which  the  patient  was  treated,  even  though  no  disinfection  was  prac- 
ticed, provided  two  weeks  have  elapsed. 

Goldberger  and  Anderson  ^  found,  as  the  result  of  experiments  upon 
monkeys,  that  the  virus  in  measles'  blood  is  filterable ;  that  is,  may  pass 
through  a  Berkefeld  filter.  In  blood  serum  it  resists  desiccation  for  25^2 
hours,  loses  its  infectivity  after  15  minutes  at  55°  C,  resists  freezing  for 
25  hours,  and  possibly  retains  some  infectivity  after  21  hours  at  15°  C. 

From  the  standpoint  of  our  present  knowledge  it  is  evident  that 
any  of  the  ordinary  germicidal  agents  sufficient  to  kill  spore-free  bac- 
teria will  serve  as  efl'ective  disinfectants  for  measles.  Aside  from  the 
few  scientific  observations  upon  the  viability  of  the  virus  of  measles, 
epidemiological  observations  have  long  pointed  out  the  fact  that  the 
virus  of  measles  is  frail  and  soon  dies  in  the  convalescent  as  well  as  in 
the  environment. 

Modes  of  Transmission. — The  virus  of  measles  is  contained  in  the 
nasal  and  buccal  secretions.  While  it  is  possible  that  the  virus  may 
leave  the  body  in  other  secretions,  it  is  highly  probable  that  the  dis- 
charges from  the  nose  and  mouth  are  the  means  of  transmitting  the 
infection  in  the  vast  majority  of  cases.  We  are  less  certain  concerning 
the  modes  of  entrance  into  the  body,  although  it  is  presumed  that  the 
virus  also  enters  by  the  mouth  and  nose. 

Mayr  ^  showed  in  1852  by  experiments  on  the  human  subject  that 
the  buccal  and  nasal  secretions  were  infective.  Anderson  and  Gold- 
berger ^  have  demonstrated  by  experiments  upon  monkeys  that  the  nasal 
and  buccal  secretions  of  uncomplicated  cases  of  measles  may  be  at  times, 
-but  are  not  always,  infective.  Hektoen  *  in  1905,  as  well  as  Goldberger 
and  Anderson,  1911,  demonstrated  that  the  virus  of  measles  is  also 
contained  in  the  circulating  blood.  The  virus  appears  in  the  blood  at 
least  24  hours  before  the  eruption  appears,  and  begins  to  diminish  about 
25  hours  after  the  first  appearance  of  the  eruption.  JSTicolli  and  Conseil, 
also  Lucas  and  Prizer  have  produced  experimental  measles  in  monkeys. 

It  has  long  been  assumed  that  the  virus  of  measles  is  carried  in  the 
fine  bran-like  desquamating  epithelium,  which  is  one  of  the  characteris- 
tics of  the  disease.  Mayr  long  ago  failed  in  his  attempts  to  inoculate 
children  with  measles  by  using  the  desquamating  epithelium.  Anderson 
and  Goldberger  also  obtained  negative  results  in  three  experiments,  in 
M^hich  it  was  shown  that  the  ''scales"  were  not  infective  for  monkeys. 

V.  A.  M.  A.,  Vol.  LVII,  No.  12,  Sept.  16,  1911,  p.  971. 

*Mayr,  Franz:     Zeitschr.  d.  k.  k.  Gesellsch.  de  Aertze  zu  Wien,  1852,  I,  13-14. 

V.  A.  M.  A.,  Vol.  LVII,  Nov.  11,  1911,  p.  1612. 

*  Experimental  Measles:     Jour.  Infect.  Dis.,  1905,  Vol.  II,  p.  238. 


17G      DISEASES   SPEEAD   THROUGH   MOUTH   AND   NOSE 

These  authorities  believe  that  it  is  highly  probable,  JI  not  altogether 
certain,  that  the  desquamating  epithelium  of  measles  in  itself  does  not 
carry  the  virus  of  the  disease.  This  conclusion  is  warrantd  by  epidemio- 
logical evidence. 

Measles  is  so  readily  communicable  that  clinicians  receive  the  im- 
pression that  the  virus  is  "volatile."  It  has  long  been  suspected  that 
the  virus  is  contained  in  the  expired  breath,  but  this  is  very  doubtful. 
In  fact,  it  may  now  be  stated  with  confidence  that  measles  is  not  air- 
borne, in  the  sense  in  which  this  term  is  usually  understood.  In  any 
case,  the  radius  of  danger  through  the  air  is  confined  to  the  immediate 
surroundings  of  the  patient — ^that  is,  within  the  danger  zone  of  droplet 
infection.  Droplet  infection  is  quite  possible,  as  the  virus  is  contained 
in  the  secretions  of  the  mouth  and  nose;  furthermore,  it  evidently  re- 
quires an  exceedingly  minute  quantity  of  the  virus  to  reproduce  the 
disease  in  man,  who  is  exquisitely  susceptible  to  this  infection. 

Chapin  has  collected  important  evidence  indicating  that  the  infec- 
tion of  measles  is  not  air-borne.  Thus,  in  the  Pasteur  Hospital,  Paris, 
each  patient  is  cared  for  in  a  separate  room  opening  into  a  common 
hall.  Trained  nurses  exercise  strict  medical  asepsis.  In  214  years  after 
this  hospital  was  opened  in  1900  many  cases  of  smallpox,  diphtheria, 
scarlet  fever,  and  126  cases  of  measles  were  cared  for.  In  no  instance 
did  measles  spread  within  the  hospital.  At  the  Children's  Hospital  in 
Paris  (Hopital  des  Infants  Malades),  instead  of  being  in  separate  rooms, 
the  beds  are  separated  only  by  partitions.  Strict  asepsis  is  observed. 
Of  5,017  cases  there  were  only  7  cross-infections,  6  of  measles  and  1  of 
diphtheria.  Dr.  Moizard  thinks  that  this  experience  proves  that  even 
measles  is  not  air-borne,  for  the  few  cases  of  this  disease  which  did 
arise  were  not  all  in  cubicles  adjoining  those  occupied  by  measles  patients. 
Grrancher  in  another  Paris  hospital  had  two  Avards  in  which  there  were 
no  partitions,  but  only  wire  screens  around  the  beds,  simply  as  a  re- 
minder for  the  nurses.  Of  6,541  patients  treated  from  1890-1900,  115 
contracted  measles,  7  scarlet  fever,  and  1  diphtheria.  Grancher  insists 
that  measles  is  probably  not  an  air-borne  disease.  Adjacent  patients  do 
not  necessarily  infect  one  another.  At  various  English  hospitals  similar 
methods  have  been  tried  with  success.  These  various  hospital  experiences 
indicate  that  the  danger  of  aerial  infection  in  measles  is  much  less 
than  is  generally  supposed. 

The  infection  of  measles  is  usually  transmitted  more  or  less  directly 
from  person  to  person  by  means  of  the  excretions  from  the  mouth  and 
nose,  and  most  often  during  the  early  stages  of  the  disease.  Measles 
may  be  transmitted  by  third  persons  or  by  fomites,  though  such  in- 
stances are  rather  exceptional. 

Prevention. — The  suppression,  of  measles  is  one  of  the  most  difficult 
problems  we  have  to  face,  for  the  reason  that  the  disease  is  one  of  the 


MEASLES  17? 

most  highly  communicable  of  all  infections,  and  for  the  further  reason 
that  it  is  most  contagious  during  the  preeruptive  stage.  To  the  student 
of  preventive  medicine  the  problem  of  measles  is  very  similar  to  that 
of  smallpox,  and  the  final  control  will  probably  have  to  await  a  specific 
prophylactic  measure.  Improved  sanitation,  better  hygiene,  and  the 
general  advance  of  civilization,  which  have  made  such  a  marked  im- 
pression upon  typhus  fever,  relapsing  fever,  typhoid  fever,  and  other 
"filth"  diseases,  have  no  influence  whatever  upon  such  infections  as 
measles  or  smallpox. 

Measles  is  such  a  common  disease  that  parents  are  prone  to  take 
little  pains  to  avoid  the  infection;  they  even  sometimes  purposely  ex- 
pose their  children.  This  is  a  mistaken  attitude.  Special  care  should 
be  exercised  especially  during  the  first  five  years  of  life,  as  over  90  per 
cent,  of  the  fatal  cases  occur  in  this  period.  While  it  may  be  almost 
hopeless  to  lessen  the  morbidity  in  measles,  it  is  quite  possible  to  ma- 
terially decrease  the  mortality  by  simply  delaying  the  age  incidence. 

Clinical  experience  plainly  indicates  that  few  people  die  of  measles 
if  properly  cared  for.  The  mortality  may,  therefore,  be  decreased  by 
careful  nursing  and  protection,  especially  from  pneumonia,  which  is 
one  of  the  most  dangerous  complications.  Newman  sums  up  the  mat- 
ter of  prophylaxis  when  he  states  that  "the  prevention  and  control  of 
measles,  like  that  of  whooping-cough  and  tuberculosis,  is  largely  in  the 
hands  of  the  public  themselves." 

In  the  present  state  of  our  knowledge  the  prophylaxis  of  measles 
rests  almost  entirely  upon  one  measure — isolation.  Chapin  believes  that 
isolation  has  been  a  failure  in  measles.  This  is  because  of  the  unrecog- 
nized but  infectious  preeruptive  stage.  "No  amount  of  isolation  after 
the  disease  is  recognized  can  atone  for  the  harm  done  before  the  diagnosis 
is  made."  Isolation,  however,  accomplishes  one  worthy  object,  viz., 
the  prevention  of  further  damage.  Isolation,  as  carried  out  in  our  large 
cities,  has  had  no  apparent  effect  upon  the  prevalence  of  the  disease. 
In  Aberdeen,  restrictive  measures  apparently  protected  only  7  to  10  per 
cent,  of  the  population. 

Despite  its  limitations,  isolation  is  quite  worth  while.  Cases  should 
be  at  once  reported  to  the  health  officer,  the  house  placarded,  and  visit- 
ing prohibited.  Quarantine  should  not  be  raised  nor  should  the  child 
be  permitted  to  retur^i  to  school  until  the  manifestations  of  the  disease 
have  disappeared.  Measles  may  be  treated  in  the  household,  but  it  is 
difficult  under  ordinary  circumstances  to  prevent  the  spread  of  the  dis- 
ease to  the  other  children.  If  the  case  is  treated  at  home,  the  children 
who  have  not  had  the  disease  should  be  sent  away,  but  kept  under  observa- 
tion and  also  under  conditions  that  will  protect  other  children  in  case  the 
disease  develops. 

Mild  atypical  and  unrecognized  cases  of  measles  occur,  but  are  far 


178      DISEASES   SPKEAD   THKOUGH  MOUTH  AND   NOSE 

less  numerous  than  such  cases  in  scarlet  fever,  diphlhoria,  and  typhoid. 
Clinical  evidence  points  to  the  fact  that  "carriers"  of  measles  do  not 
occur.  The  disease  is  usually  spread  directly  from  person  to  person, 
rarely  indirectly  through  a  third  person,  or  by  fomites.  Physicians  may 
convoy  the  infection  to  healthy  children.  I  am  convinced  that  I  carried 
the  disease  to  my  own  son.  When  measles  is  conveyed  by  a  third  person 
or  by  fomites  it  is  by  means  of  contamination  with  the  fresh  buccal, 
nasal,  or  bronchial  secretions  upon  the  hands,  handkerchief,  or  some 
other  object  that  comes  in  contact  with  the  mouth  or  nostrils  of  a  sus- 
ceptible child.  Physicians  may  readily  avoid  this  danger  by  wearing  a 
gown  and  carefully  washing  the  hands,  face,  and  hair,  and  waiting  a 
reasonable  time  before  visiting  healthy  children. 

Terminal  fumigation  is  of  comparatively  little  value  in  preventing 
the  spread  of  measles.  After  the  patient  is  released  from  isolation  a 
general  fumigation  with  formal dehyd  may  be  practiced,  especially  if 
healthy"  children  are  soon  to  occupy  the  playroom  or  bedroom.  However, 
if  from  3  to  3  weeks  have  elapsed,  there  is  practically  no-  danger  in  a 
well- ventilated,  sunny,  and  clean  room.  All  bedding,  towels,  handker- 
chiefs, and  other  fabrics  that  have  been  exposed  should  be  boiled  or 
otherwise  disinfected.  Terminal  fumigation  for  measles  has  been  given 
up  in  New  York  and  other  cities  as  unnecessary. 

The  question  of  closing  the  schools  in  order  to  prevent  the  spread 
of  measles  requires  consideration.  If  the  school  is  closed  at  the  begin- 
ning of  an  outbreak  and  the  disease  continues  to  spread  after  two  weeks, 
little  more  will  be  gained  in  keeping  the  school  closed,  for  it  must  then 
be  evident  that  other  factors  are  at  work  in  spreading  the  infection. 
As  the  disease  is  mainly  spread  in  the  preemptive  stage,  it  is  sufficient 
to  examine  the  children  each  morning  before  they  enter  school  for  symp- 
toms of  a  cold,  injection  of  the  eyes,  running  at  the  nose,  cough,  sore 
throat,  fever,  etc.  All  such  cases  should  be  sent  home  to  await  further 
developments.  Better  results  are  often  obtained  by  daily  inspection  than 
by  closing  the  schools. 

McVail  suggests  that  when  a  child  develops  measles  all  the  children 
exposed  may  be  allowed  to  continue  at  school  8  or  10  days,  and  then 
excluded  for  a  week  to  ten  days,  when  those  who  do  not  develop  the  dis- 
ease may  be  allowed  to  return.  This  is  a  rational  plan  used  in  certain 
districts  in  England.  When  measles  breaks  out  in  an  orphan  asylum, 
a  public  institution,  or  an  encampment,  the  only  chance  of  checking  the 
spread  of  the  disease  is  through  the  early  recognition  of  iirst  symptoms 
and  isolation. 

SCARLET   FEVER 

Scarlet  fever  is  an  acute  febrile  infection  characterized  by  a  diffuse 
eruption  which  appears  during  the  first  day  or  two  of  the  fever,  and 


SCAELET    FEYER  179 

sore  throat  of  variable  intensity.  The  seasonal  prevalence  of  scarlet 
fever  resembles  that  of  diphtheria.  The  disease  increases  in  the  fall 
of  the  year,  due,  in  part,  to  the  gathering  of  children  in  the  schools. 
The  period  of  incubation  is  from  1  to  7  days;  usually  2  to  4,  In  a 
few  instances,  in  which  individuals  have  been  inoculated  with  the  blood 
of  scarlet  fever  patients,  3  to  4  days  elapsed  before  the  onset  of  symp- 
toms. For  public  health  purposes  the  maximum  period  of  incubation  is 
placed  at  7  days.  Scarlet  fever  is  rare  in  the  tropics;  when  introduced 
it  soon  dies  out.  There  is  probably  always  more  or  less  scarlet  fever  in 
every  thickly  settled  district  in  the  temperate  zone.  The  infection  is  kept 
alive  largely  through  the  mild  and  unrecognized  cases.  Scarlet  fever 
varies  greatly  in  intensity  in  different  outbreaks.  In  some  epidemics 
the  death  rate  is  30  per  cent;  in  others  it  is  practically  nil. 

Landsteiner,  Levaditi  and  Prasek  ^  apparently  succeeded  in  transfer- 
ring scarlet  fever  to  chimpanzees  and  also  to  monkeys.  The  animals 
were  inoculated  both  by  applying  throat  swabs  from  scarlet  fever  patients 
to  the  pharynx  of  the  animals,  and  also  by  injecting  the  animals  with 
blood  from  scarlet  fever  patients.  While  the  nature  of  the  virus  is  still 
unknown,  it  seems  to  be  present  in  the  tonsils,  tongue,  blood,  lymph 
nodes,  and  pericardial  fluid. 

The  cause  of  scarlet  fever  is  not  known.  Mallory  and  Medlar  ^  have 
described  a  small  bacillus  (B.  scarlaiinae)  in  the  mucous  membrane  of 
the  tonsils  and  throat  and  upper  respiratory  passages  in  the  early  stages 
of  the  disease.  It  is  difficult  to  find  this  bacillus  after  the  second  or 
third  day  following  the  eruption.  It  is  not  very  virulent  in  itself,  but  it 
opens  the  way  for  streptococcus  invasion,  and  seems  to  favor  its  growth. 
Streptococci  are  almost  constantly  found  in  the  throat  and  blood  of 
scarlet  fever  cases.  Klein  in  1885  was  the  first  to  advocate  the  Strepto- 
coccus scarlatinae  as  the  specific  cause  of  scarlet  fever.  Kurth  assigns  an 
etiological  factor  to  the  Streptococcus  conglomeratus.  It  is  said  to  pro- 
duce a  rash  in  animals  and  men  who  are  injected  with  it.  Streptococci 
of  the  beta  type  described  by  Theobald  Smith  are  the  pathogenic  type 
frequently  found  in  scarlet  fever.  The  chief  reasons  for  considering 
streptococci  as  the  cause  of  scarlet  fever  are  that  they  are  constantly 
found  in  the  throat  of  scarlet  fever  patients ;  that  frequently  they  can  be 
isolated  from  the  blood  of  scarlet  fever  patients  during  life,  and  almost 
constantly  after  death;  the  cause  of  the  complications  and  death  in  the 
majority  of  cases  of  scarlet  fever  is  due  to  a  streptococcus.  It  is  probable, 
however,  that  streptococci  play  a  secondary  role  in  scarlet  fever  as  they  do 
in  smallpox;  the  disease  itself  may  be  due  to  a  protozoon-like  body  de- 
scribed by  Mallory,  which  lowers  the  resistance  of  the  organism  to  strep- 
tococcal invasion. 

^  Ann.  de  I'lnst.  Pasteur,  Oct.,  1911.  XXV,  No.  10,  p.  754. 

"Journal  of  Medical  Research,  March,  1916,  Vol.  XXXIV,  No.  1,  pp.  127-130. 


180      DISEASES   SPREAJ)   ^rifROUGH   MOU'JMl   ANJ)   NOSK 

Modes  of  Transmission. — It  is  taken  for  granted  that  the  virus  of 
scarlet  fever  is  contained  in  the  secretions  from  the  nose,  thi-oat,  and 
respiratory  tract.  The  virus  probably  enters  by  the  mouth  and  respira- 
tory passages.  It  is  commonly  stated  that  scarlet  fever  is  not  contagious 
during  the  period  of  incubation;  little,  if  any,  during  the  period  of 
invasion,  and  most  contagious  during  the  period  of  eruption.  The  con- 
tagiousness depends  upon  the  discharge  of  the  virus,  which  in  turn  de- 
pends upon  the  condition  of  the  mucous  membranes  of  the  nose  and 
throat.  This  varies  in  different  cases,  but  as  the  catarrhal  symptoms  are 
usually  most  pronounced  during  the  time  of  the  rash  this  is  therefore 
the  time  of  greatest  danger  in  the  average  case.  Scarlet  fever  may  be 
communicable  from  the  beginning  of  mucous  membrane  lesions  until 
long  after  convalescence.  Scarlet  fever  is  readily  communicable,  but  less 
so  than  measles  or  smallpox ;  it  ranks  about  with  diphtheria. 

It  has  long  been  accepted  and  taught  by  the  medical  profession 
that  the  desquamation  is  the  most  infectious  stage  of  scarlet  fever,  and 
it  is  now  very  difficult  to  unteach  the  public  this  erroneous  view.  It  is 
now  known  that  desquamating  patients  may,  as  a  rule,  be  safely  released 
from  quarantine  in  the  6th  week  of  their  attack  of  scarlet  fever,  provided 
they  have  no  mucous  complications  or  other  sequelae.  Convalescents  may 
be  a  source  of  danger  to  others  even  after  desquamation  has  ceased. 
This  fact  has  been  emphasized  from  a  study  of  the  so-called  "return 
cases."  Thus  convalescents  are  released  from  hospital  and  permitted  to 
return  home;  soon  another  case  appears  in  one  of  the  members  of  the 
household,  who  in  turn  comes  to  the  hospital.  Neech  in  a  study  of 
15,000  cases  found  that  the  percentage  of  return  cases  was  1.86  in  those 
cases  who  submitted  to  an  average  period  of  isolation  of  49  days  or  under. 
With  an  average  period  of  50  to  56  days  the  percentage  was  1.12 ;  where 
the  isolation  extended  to  between  57  and  65  days  the  percentage  of  return 
cases  was  1.  McCoUom  states  that  in  the  South  Department  of  the  City 
Hospital,  Boston,  the  children  are  kept  50  days,  and  no  patient  is  released 
who  has  a  discharge  from  the  nose  or  an  abnormal  condition  of  the 
throat.  Of  3,000  patients  discharged  from  the  scarlet  fever  ward,  1.7 
per  cent,  of  return  cases  occurred. 

There  is  no  accurate  means  of  determining  just  how  long  a  child 
remains  infective  after  scarlet  fever.  The  period  of  detention  varies 
very  much.  Fifty  days  may  be  taken  as  a  working  average.  In  New 
Haven  and  Seattle  cases  are  dismissed  after  desquamation ;  in  North  Da- 
kota 5  days  after  desquamation ;  in  Ohio  and  South  Dakota  10  days  after 
desquamation.  In  various  cities  and  states  the  period  of  isolation  varies 
from  3  weeks  to  8  weeks  unless  the  physician  certifies  that  desquamation 
has  ceased.  In  Milwaukee,  Paterson,  and  Pittsburgh  it  is  never  main- 
tained longer  than  30  days,  even  if  desquamation  continues.  Owing  to 
our  lack  of  knowledge  on  the  subject,  the  period  of  isolation  must  remain 


SCAKLET    FEVEE  '  181 

more  or  less  guesswork.  An  unduly  long  detention  is  a  hardship  upon 
the  patient  and  the  family ;  on  the  other  hand,  a  scant  period  is  hazard- 
ous to  the  community.  Cases  Avith  rhinorrhea,  otorrhea,  throat  trouble, 
or  discharging  abscesses  must  receive  special  care,  as  the  secretions  from 
these  parts  are  now  known  to  remain  infective  for  a  long  time.  Any 
unhealed  area  of  the  body  surface  either  cutaneous  or  mucous  may  con- 
tain the  virus. 

Many  cases  of  walking  scarlet  fever  present  little  further  evidence 
than  a  passing  sore  throat.  These  cases  doubtless  spread  the  disease, 
esjjecially  in  schools.  Third  persons  may  carry  the  virus  perhaps  on 
their  person  and  perhaps  also  as  carriers.  Toys,  cups,  spoons,  pencils^ 
chewing  gum,  candy,  drinking  glasses,  thermometers,  handkerchiefs,  and 
other  objects  contaminated  by  the  secretions  of  the  mouth  play  the  same 
role  here  that  they  do  in  diphtheria.  Scarlet  fever  is  not  air-borne;  at 
least  the  radius  of  infection  is  limited  to  droplet  infection. 

Direct  contact  is  the  most  important  and  most  frequent  method  of 
transmitting  scarlet  fever.  The  communicability  is  indicated  by  the  fact 
that  less  than  3  per  cent,  of  the  nurses  at  the  South  Department  (Boston 
City  Hospital)  contract  the  disease;  and  only  a  small  fraction  of  a  per 
cent,  of  medical  students.  Place  believes  that  a  large  majority  of  people, 
probably  75  per  cent.,  escape  scarlet  fever. 

MiLK-BOKFE  Scarlet  Fever. — Milk  is  a  rather  frequent  vehicle  for 
scarlet  fever  infection.  The  milk  is  practically  always  contaminated 
from  human  sources.  There  is,  however,  some  suspicion  that  strepto- 
coccal diseases  of  the  cow  may  in  some  instances  be  identical  with  scarlet 
fever.  This  is  doubtful.  It  is  believed,  however,  that  such  diseases  of  the 
udders  of  the  cows  may  cause  outbreaks  of  an  infection  resembling  scarlet 
fever.  Trask  collected  51  scarlet  fever  epidemics  reported  as  spread 
by  milk.  Twenty-five  of  these  occurred  in  the  United  States  and  26  in 
Great  Britain.  In  35  of  the  epidemics  a  case  of  scarlet  fever  was  found 
at  the  producing  farm,  the  distributing  dairy,  or  milkshop  at  such  a  time 
as  to  have  been  the  possible  source  of  infection ;  in  3  of  the  outbreaks  the 
bottles  returned  from  infected  households  and  refilled  without  previous 
sterilization  were  given  as  the  source  of  infection ;  in  3  of  the  outbreaks 
scarlet  fever  persons  handled  the  milk  or  milk  utensils,  and  in  12  of  the 
outbreaks  the  cows  were  milked  by  persons  having  scarlet  fever ;  in  one 
epidemic  the  same  person  nursed  the  sick  and  handled  the  milk ;  in  2 
of  the  outbreaks  the  source  of  infection  was  supposed  to  be  due  to  disease 
of  the  cow.  A  milk-borne  outbreak  in  Washington  was  traced  to  a  con- 
valescent with  a  discharging  ulcer  on  the  finger.  Milk-borne  outbreaks 
of  scarlet  fever  are  sometimes  very  extensive. 

An  unusually  extensive  milk-borne  outbreak  of  scarlet  fever  occurred 
in  Boston  during  April  and  May,  1910.  A  total  of  842  cases  were 
reported  from  Boston  and  the  surroiniding  towns  of  Chelsea,  Wintlirop, 


182      DISEASES   SPEEAD   THKOUGH   MOUTH   AND   NOSE 

Cambridge,  Somerville,  Maiden,  and  Everett.  Investigation  showed  that 
most  of  the  cases  oecurred  on  the  route  of  a  large  milk  contractor.  Of 
the  409  cases  in  Boston,  286,  or  nearly  70  per  cent.,  were  on  the  route 
of  this  dealer;  while  123,  or  30  per  cent.,  used  other  milk.  Of  the  155 
cases  that  occurred  in  Cambridge,  126,  or  over  80  per  cent.,  were  on  the 
route  of  the  same  dealer.  About  the  same  proportion  of  the  cases  in 
the  other  cities  used  the  milk  of  this  dealer.  The  cases  appeared  sud- 
denly April  25th,  and  the  outbreak  ceased  May  7th.  The  epidemic 
reached  its  highest  mark  on  April  29th,  when  128  cases  were  reported. 
The  indications  were  plain  that  the  outbreak  vi^as  the  result  of  more 
than  a  single  infection.  The  milk  was  pasteurized  at  60°  C.  for  30 
minutes  on  April  27th,  and  three  days  following  there  was  a  notable  and 
sharp  decline  in  the  number  of  cases.  The  source  of  the  infection  could 
not  be  traced,  although  it  probably  consisted  of  a  "missed"  case  on  one  of 
the  250  dairy  farms  from  which  the  dealer  obtained  this  particular  sup- 
ply of  milk. 

Immunity. — One  attack  of  scarlet  fever  usually  protects  against  sub- 
sequent attacks.  In  rare  instances  second  attacks  may  occur  after  an 
interval  of  several  years.  Children  under  10  are  most  susceptible.  Suck- 
lings are  rarely  attacked,  though  susceptible.  After  the  lOtli  year  the 
resistance  to  the  disease  increases.  Ninety  per  cent,  of  the  fatal  cases 
occur  in  children  under  10  years  old.  The  reason  why  infants  at 
the  breast  are  less  likely  to  take  the  disease  may  be  on  account  of  the 
diminished  chances  of  the  infection  entering  the  mouth.  The  immunity 
acquired  in  later  life  may  in  part  be  due  to  previous  unrecognized  mild 
attacks. 

Prophylaxis. — Prophylaxis  in  scarlet  fever  must  necessarily  be  in 
excess  of  the  requirements,  awaiting  more  precise  knowledge  of  its 
cause  and  modes  of  transmission.  The  essential  features  of  prevention 
consist  in  isolation  and  disinfection.  It  is  important  to  recognize  the 
mild  cases  in  schools  through  an  efficient  medical  inspection.  The  answer 
to  the  question  whether  schools  should  be  closed  when  scarlet  fever  breaks 
out  varies  with  the  circumstances.  In  country  districts  this  is  advisable, 
as  the  children  may  be  kept  separate,  but  in  the  cities  little  is  gained. 
Better  results  may  often  be  achieved  by  daily  inspection  of  all  pupils  than 
by  closing  the  school.  All  members  of  the  household,  where  a  person 
is  ill  with  scarlet  fever,  should  be  excluded  from  school  until  one  week 
has  expired  from  the  last  possible  exposure,  unless  immunized  by  a 
previous  attack  of  the  disease.  All  other  members  of  the  household  may 
be  allowed  to  continue  their  usual  occupations  except  those  engaged  in 
handling  milk.  There  is  no  objection  to  treating  a  case  of  scarlet  fever 
in  the  household,  provided  a  suitable  room  and  trained  attendant  may  be 
had.  The  infection  may  be  confined  to  the  sick  room,  but  it  is  preferable 
to  take  no  chances  and  send  the  susceptible  individuals  out  of  the  house. 


SCAELET   FEVEE  183 

The  nurse  should  use  the  precautions  described  for  diphtheria,  smallpox, 
or  measles.  The  physician  should  wear  a  gown  and  thoroughly  disinfect 
his  hands  and  other  exposed  parts  after  the  visit.  Special  care  must  be 
taken  with  the  thermometer  and  other  instruments.  The  physician  may 
find  the  necessary  precautions  and  disinfection  to  be  irksome,  but  they 
should  not  be  shirked  in  justice  to  his  other  patients  and  the  community. 

The  discharges  from  the  mouth,  nose,  and  respiratory  passages,  etc., 
should  be  collected  upon  suitable  fabrics  and  burned.  Bed  and  body 
clothing,  dishes,  and  other  exposed  objects  must  be  disinfected.  Care 
must  be  taken  concerning  remnants  of  food  from  the  sick  room. 

Scarlet  fever  is  not  as  highly  contagious  as  measles,  but  the  meas- 
ures employed  should  be  practically  the  same  until  at  least  we  have 
more  definite  knowledge  concerning  the  channels  of  entrance  and  exit 
of  the  virus  and  its  modes  of  transmission.  The  virus  of  scarlet 
fever  is  more  resistant  than  that  of  measles.  It  clings  persistently  to 
clothing  and  various  objects.  A  terminal  fumigation  with  formaldehyd 
gas  may  be  practiced,  although  little  seems  to  be  gained  thereby.  A 
thorough  cleansing  of  all  surfaces,  with  a  good  sunning  and  airing  of 
the  room,  is  always  in  order.  All  fabrics  and  other  objects  that  have 
been  exposed  should  be  disinfected.  The  virus  is  killed  with  agents 
that  destroy  non-spore-bearing  bacteria.  In  Glasgow  a  sanitary  wash- 
house  has  been  established,  where  the  clothing  of  scarlet  fever  cases  may 
be  disinfected  and  washed.  This  is  a  commendable  example  that  might 
be  followed  with  advantage  by  other  cities.  The  prevention  of  nephritis, 
which  is  a  frequent  and  serious  sequel  of  scarlet  fever,  consists  in  absolute 
rest  in  bed  for  four  weeks  even  in  the  mildest  cases,  and  a  low  protein 
diet — chiefly  bread  and  milk. 

Specific  Prophylaxis. — Attempts  at  artificial  immunity  by  inocula- 
tion have  failed  because  the  inoculated  disease  does  not  prove  milder,  as 
in  the  case  of  smallpox.  Whether  immunity  may  be  secured  through 
general  hygiene  is  doubtful,  although  good  care  of  the  teeth  and  gums, 
normal  tonsils  and  healthy  mucous  membranes  of  the  throat  may  afford 
some  protection. 

Gabritschewsky  first  proposed  the  use  of  streptococcus  vaccines  as  a 
prophylaxis  against  scarlet  fever.  The  results  of  streptococcal  vaccines  in 
Eussia  indicate  that  vaccinated  persons  contract  the  disease  in  from  0 
to  8.5  per  cent,  in  different  villages  as  contrasted  with  13.3  per  cent,  to 
70.6  per  cent,  in  unvaccinated.  Of  ninety-one  unvaccinated  persons  re- 
ported by  Smirnoff,  37.3  per  cent,  developed  scarlet  fever  as  contrasted 
with  3.93  per  cent,  of  127  vaccinated.  The  value  of  these  vaccines  for 
scarlet  fever  needs  confirmation  and  until  more  evidence  is  obtained  we 
must  remain  sceptical  as  to  their  prophylactic  value. 

Moser's  polyvalent  antistreptococcus  serum  has  been  used  in  the  treat- 
ment of  the  disease,  but  has  not  been  advocated  as  a  prophylactic. 


184      JUiSEASEJS   SlTtEAD    'rillfOLKai   MOU'lli   AM)   NOSE 


WHOOPING-COUGH 

Whoop ing-eoiigh  oeciiTs  in  epidemics,  M'hich  vary  greatly  in  viru- 
lence, intensity,  and  mortality.  Tlie  disease  is  more  frequent  and  severe 
in  cold  climates;  otherwise  uninfluenced  by  season  and  weather.  The 
cause  of  whooping-cough  is  a  small  bacillus,  described  by  Bordet  and 
Gengou.'-  This  bacillus  is  found  most  readily  in  the  beginning  of  the 
disease,  in  the  matter  from  the  depths  of  the  bronchi  brought  up  during 
the  paroxysms.  In  this  exudate,  which  is  white,  thick,  and  rich  in 
leucocytes,  the  bacilli  exist  in  considerable  numbers  and  sometimes  in 
almost  pure  culture. 

Mode  of  Transmission. — Whooping-cough  is  usually  transmitted 
directly  from  person  to  person  in  the  same  ways  that  diphtheria  and  other 
infections  contained  in  the  secretions  of  the  mouth  and  nose  are  spread. 
Handkerchiefs,  toys,  drinking  cups,  roller  towels,  and  other  objects  re- 
cently contaminated  with  the  infective  secretions  may  act  as  vectors. 
It  may  also  be  transmitted  by  droplet  infection,  although  in  the  ordinary 
sense  whooping-cough  is  not  air-borne. 

Jahn  and  others  called  attention  to  the  fact  that  domestic  animals 
may  be  affected  by  whooping-cough,  and  that  they  may  be  the  means  of 
transmitting  it  to  children.  It  has  been  observed  in  dogs,  and  has  also 
been  noted  in  cats.  Whooping-cough  may  be  reproduced  in  puppies 
by  dropping  a  pure  culture  into  the  nares;  once  started,  it  is  readily 
transmitted  from  puppy  to  puppy.  Ivlimenco  ^  and  Fraenkel  ^  were  able 
to  produce  what  seemed  like  typical  pertussis  in  monkeys,  and  Inabo  * 
showed  that  injection  of  the  bacillus  in  an  ape  gave  rise  to  a  typical 
whooping-cough  with  an  incubation  period  of  13  days.  Kittens  and  pup- 
pies seldom  take  the  disease  under  ordinary  circumstances  and  for  prac- 
tical purposes  of  prevention  are  usually  disregarded.  Mallory  and 
Horner  ^  have  shown  that  bacilli  are  found  in  masses  in  the  superficial 
layer  of  the  trachea,  thereby  mechanically  paralyzing  the  ciliae. 

Whooping-cough  is  apparently  not  contagious  during  the  period  of 
incubation,  but  is  communicable  from  the  appearance  of  the  early  symp- 
toms, and  is  most  contagious  during  the  early  stage.  It  may  be  trans- 
mitted in  the  late  stages  and  after  convalescence.-  While  the  virus  is 
known  to  be  in  the  secretions  from  the  respiratory  tract,  all  secretions 
from  the  mouth  and  nose  (including  vomitus)  must  be  regarded  as 
infective. 

Immunity, — There  is  no  natural  immunity  to  whooping-cough;  all 

^Ann.  de  I'Inst.  Pasteur,  Vol.  XX,  1906,  p.  731. 
'CentralU.  f.  Bakteriol.,  1908,  XLVIII,  64. 
^Munchen.  med.  Wochschr.,  1908,  LV,  1683. 
*  Ztschr.  f.  Kinderh.,  June  15,   1912. 
"Jour.  Med.  Res.,  Nov.,  1912,  XXVII,  2,  p.  115. 


WHOOPING-COUGH  185 

are  susceptible.  Whooping-cough  at  one  time  or  another  affects  almost 
every  member  of  a  community  and  causes  10,000  or  more  deaths  yearly 
in  this  country  alone.  The  greatest  susceptibility  is  between  6  months 
to  5  years.  After  5  years  the  susceptibility  decreases  with  age.  One  at- 
tack confers  a  definite  and  prolonged  immunity;  second  attacks  are 
rare. 

Prevention. — The  incubation  is  probably  2  days  to  2  weeks,  but  the 
time  is  indefinite,  owing  to  vagueness  of  the  onset  of  symptoms.  If  16 
days  have  passed  without  symptoms  the  danger  may  be  considered  as  hav- 
ing passed.  For  practical  purposes  of  prevention  14  days  will  cover  most 
cases.  The  long-drawn-out  nature  of  the  disease,  the  difficulty  of  diag- 
nosis in  the  early  stages  when  it  is  most  contagious,  and  the  fact  that 
patients  sometimes  continue  to  spread  the  infection  for  6  weeks  after 
apparent  recovery,  make  the  control  of  whooping-cough  an  exceedingly 
dilffcult  problem.  Hence,  with  whooping-cough  we  have  the  same  diffi- 
cult problem  that  confronts  us  in  the  prevention  of  measles. 

Whooping-cough  should  be  reported,  houses  placarded,  and  the  pa- 
tient isolated,  but  the  isolation  in  this  case  need  not  include  strict  con- 
finement to  a  room.  This,  in  fact,  may  be  an  unnecessary  hardship  to 
the  patient,  who  does  better  out  of  doors.  If  the  patient  is  permitted 
to  take  the  air,  he  must  avoid  contact  with  his  fellowmen  and  not  go 
to  school,  theater,  church,  public  assemblies,  nor  ride  in  street  cars  or 
public  vehicles.  Children  should  go  out  only  when  accompanied  by  an 
intelligent  caretaker  as  a  protection  to  others.  It  has  been  suggested 
tbat  children  with  whooping-cough  who  are  permitted  their  liberty 
should  be  plainly  labeled  with  a  red  cross  on  their  arm,  or  a  yellow 
flag,  or  the  word  "whooping-cough"  conspicuously  displayed  on  their 
clothing,  to  serve  as  a  warning  to  others.  Each  community  should  pro- 
vide a  hospital-farm  for  children  with  whooping-cough  who  lack  proper 
care. 

Patients  should  not  be  released  from  quarantine  until  the  spasmodic 
stage  is  over  or  until  (!  weeks  have  elapsed  since  the  onset  of  symptoms. 
The  duration  of  isolation  varies  in  different  cities ;  thus  it  is  6  weeks  in 
Montclair,  N.  J. ;  on  recovery  in  Providence ;  as  long  as  the  cough  lasts 
in  Boston.  In  Michigan  the  disease  is  considered  infectious  3  weeks 
before  the  whoop  and  4  to  6  weeks  after  apparent  recovery.  The  State 
Board  of  Health  of  Michigan  requires  disinfection  of  the  clothing  and 
premises  before  the  patient  is  released,  and  forbids  public  funerals  in 
deaths  from  whooping-cough. 

Individual  prophylaxis  consists  in  avoiding  the  infection.  The  great- 
est care  in  this  regard  should  be  taken  with  children  before  the  age 
of  5  years.  Mnety-six  per  cent,  of  the  6,324  deaths  from  whooping- 
cough  in  the  United  States  in  1906  were  in  children  under  5  years  of  age. 
Dogs,  cats,  and  other  domestic  animals  should  be  kept  away  from  the 


18G      DISEASES   SPKEAD   THROUGH   MOUTH   AND   NOSE 

patient,  and  the  possibility  of  conveying  the  disease  in  this  way  must  be 
guarded  against  in  the  susceptible. 

The  Bordet-Gengou  bacillus  is  frail  and  soon  dies  in  the  environment ; 
therefore,  terminal  fumigation  of  the  room  is  not  necessary,  although 
cleaning  and  airing  of  the  premises  are  in  order.  Handkerchiefs,  fabrics, 
toys,  and  other  objects  that  have  come  in  contact  with  the  secretions 
from  the  mouth  and  nose  should  be  boiled  or  saturated  with  a  strong 
germicidal  solution.  The  sputum  and  vomitus  should  be  disinfected  as 
for  tuberculosis. 

Whooping-cough  usually  runs  a  favorable  course  in  healthy  children 
over  five  years  old,  and  after  puberty  it  is  rarely  fatal.  The  most  im- 
portant thing  then  is  to  keep  babies  and  young  children  from  having  the 
disease.  Delaying  the  age  incidence  will  materially  decrease  the  mor- 
tality. Particular  care  should  be  taken  during  and  for  several  months 
following  convalescence  to  prevent  the  development  of  tuberculosis. 

Schools  need  not  be  closed  on  account  of  whooping-cough.  Daily  in- 
spection of  pupils  may  achieve  better  results.  The  well  children  of  a 
household,  where  a  person  is  ill  with  whooping-cough,  should  be  excluded 
from  school  unless  they  have  had  the  disease  or  until  two  weeks  have 
elapsed  since  the  last  exposure,  and  then  only  provided  they  are  free  from 
catarrhal  symptoms.  Other  members  of  the  household  may  be  allowed 
to  follow  their  usual  occupations. 

Hess  has  recently  used  vaccines  of  the  Borden-Gengou  bacillus  as  a 
prophylactic  with  seeming  success.^ 

The  control  of  whooping-cough  is  a  matter  which  is  largely  in  the 
hands  of  the  public  itself.  The  dangerous  nature  of  this  infection 
should  be  emphasized,  and  people  taught  that  it  is  contagious  both  be- 
fore and  after  the  "whoop."  Mild  cases  which  do  not  have  the  charac- 
teristic whoop  spread  the  disease ;  this  is  especially  common  in  adults. 

Mortality. — ^^The  dangerous  nature  of  whooping-cough  is  not  gen- 
erally realized.  Whooping-cough  almost  everywhere  causes  more  deaths 
than  scarlet  fever.  Many  deaths  registered  as  bronchitis  and  broncho- 
pneumonia are  secondary  to  whooping-cough.  In  the  United  States  in 
1910  the  death  rate  per  100,000  was  as  follows:  Whooping-cough  11.4; 
scarlet  fever  11.6;  measles  12.3;  and  diphtheria  21.4.  In  Glasgow  the 
annual  mortality  from  whooping-cough  for  40  years,  1855-1894,  was  13.5 
per  hundred  thousand  inhabitants,  and  exceeded  that  from  any  other 
acute  communicable  disease.  In  England  and  Wales  in  1891  more 
deaths  occurred  from  whooping-cough  than  from  measles,  diphtheria, 
scarlet  fever,  or  typhoid  fever.  The  mortality  figures  would  be  still 
higher  if  all  the  deaths  directly  or  indirectly  due  to  it  were  completely 
reported,  for  the  fatal  termination  is  usually  due  to  complications  and 
sequelae  which  occur  in  one-third  to  one-fourth  of  all  cases.    As  a  result 

'Jour.  A.  M.  A.,  XLIII,  2,  Sept.  19,  1914,  p.  1007. 


MUMPS  187 

of  these  complications  the  original  disease  is  frequently  lost  sight  of 
entirely  in  the  vital  statistics.  According  to  Farr's  law — that  contagious 
diseases  increase  as  density  of  population  increases — the  death  rate  from 
whooping-cough  in  our  country  will  undoubtedly  increase  in  our  more 
sparsely  settled  states  with  increasing  population  and  rapidly  extending 
lines  of  railroad  and  other  facilities,  and  with  easy,  frequent,  and  rapid 
movements  of  the  people. 

The  gravity  of  whooping-cough  is  scarcely  appreciated,  either  by  the 
physician  or  the  public,  and  there  is  much  heedless  neglect  with  reference 
to  the  prevention  of  this  infection. 


MUMPS 

Mumps  usually  occurs  between  the  ages  of  5  to  15  years.  There  is 
decreased  susceptibility  both  before  and  after  this  time.  One  attack 
usually  confers  immunity,  but  second  attacks  are  by  no  means  rare,  and 
third  attacks  are  sometimes  reported.  The  disease  may  occur  as  epi- 
demics in  institutions,  which  usually  develop  slowly  and  last  a  long  time. 
Orchitis  is  a  frequent  and  painful  complication  and  when  both  testicles 
are  involved  may  cause  sterility.  Mumps  is  contagious  before  the  symp- 
toms appear,  and  for  some  time,  even  6  weeks,  after  symptoms  have  dis- 
appeared. The  disease  is  usually  spread  by  direct  contact;  rarely  by 
indirect  contact  or  by  a  third  person.  It  is  not  air-borne.  The  virus  is 
contained  in  the  secretions  from  the  mouth  and  perhaps  the  nose.  The 
incubation  is  variously  stated  at  from  4-25  days;  it  is  usually  prolonged. 
For  public  health  purposes  the  maximum  period  of  incubation  is  placed 
at  21  days. 

Martha  Wollstein  ^  has  shown  that  the  salivary  secretion  in  mumps 
contains  a  virus,  which  when  filtered  and  injected  into  the  parotid  glands 
and  testicles  of  cats,  causes  pathological  changes  resembling  mumps  in 
human  beings. 

Mumps  is  required  to  be  reported  in  Maryland,  Grand  Eapids,  and 
Ealeigh,  and  placarded  in  Cleveland.  Prevention  depends  upon  the  usual 
practice  of  isolation  and  disinfection. 

Hess  ^  injected  6  to  8  c.  c.  of  blood  of  convalescents  intramuscularly 
into  17  children.  None  of  these  children  developed  mumps,  although 
exposed  to  it  in  an  institution  where  the  disease  was  epidemic.  If  con- 
firmed, this  procedure  could  be  made  use  of  in  the  home  as  well  as  in 
institutions. 

"■Journ.  Exp.  Med.,  March,  XXITT,  No.  3,  pp.  26.5-429. 

'Proceedings  of  the  Society  for  Experimental  Biology  and  Medicine,  Apr.  21^ 
19],5,  XII,  7,  p.   144. 


l.ss       DISMASKS    SI'I{I':AI)    TIIKOlJOil    MOUTH    AM)    XOSK 


LOBAR    PNEUMONIA 

Lobar  pneumonia  is  a  eommnni cable  disease  which  should  be  classi- 
fied with  the  infectious  fevers.  If  pneumonia  were  a  new  disease  it 
would  be  regarded  as  "contagious,"  and  its  spread  would  be  guarded 
against  by  isolation  and  the  application  of  antiseptic  principles.  Many 
different  infections  are  caused  by  the  pneumococcus,  but  here  we  will 
consider  only  the  specific  self-limiting  disease  associated  with  massive 
involvements  of  one  or  more  lobes  of  the  lung,  known  as  lobar  or  croupous 
pneumonia. 

The  pneumococcus  is  found  not  alone  in  the  local  lung  lesions,  but 
it  frequently  invades  the  blood.  When  this  happens  it  increases  the 
severity  of  the  disease. 

Pneumonia  is  one  of  the  most  prevalent  and  fatal  of  all  acute  diseases. 
As  a  cause  of  death  it  rivals  and  sometimes  exceeds  tuberculosis.  Accord- 
ing to  the  U.  S.  Census  of  1890,  over  9  per  cent,  of  all  deaths  were 
due  to  pneumonia,  and  in  1900  over  10.5  per  cent.  Pneumonia  is  prob- 
ably on  the  increase,  owing  to  factors  favoring  the  spread  of  the  infection, 
especially  crowding ;  and  also  to  certain  devitalizing  influences  of  modern 
life  which  heighten  susceptibility  to  the  disease;  further,  more  persons 
are  now  saved  from  the  acute  and  fatal  infections  of  childhood  and  adoles- 
cence to  become  victims  of  pneumonia  later  in  life. 

Pneumonia  occurs  everywhere,  in  all  climates,  at  all  times  of  the 
year,  in  both  sexes,  and  at  all  ages ;  it  is  more  frequent,  however,  during 
the  cold  months  of  the  year.  The  incidence  is  marked  at  both  extremes 
of  life.  It  is  common  in  children  under  six  years;  between  the  sixth 
or  fifteenth  year  the  predisposition  is  less  marked,  but  for  each  subsequent 
decade  it  increases. 

Pneumonia  occurs  in  well-marked  epidemics.  Wells  gives  an  ex- 
haustive tabulation  of  the  epidemics  of  pneumonia  extending  back  to 
1440.^  Epidemics  of  pneumonia  have  occurred  in  all  parts  of  the  world : 
in  Alaska,  at  Erlangen,  Boston,  Ireland,  Italy,  France,  Switzerland,  and 
on  board  ships.  The  disease  has  also  been  observed  to  spread  in  hospitals 
and  in  houses.  The  excessive  prevalence  of  pneumonia  often  found  in 
barracks  and  among  working  people,  as  at  Panama  and  at  the  African 
mines,  is  due  to  contact  infection  resulting  from  overcrowding.  It  is 
quite  proper  to  regard  pneumonia  as  pandemic. 

A  great  advance  in  our  knowledge  of  pneumonia  has  recently  been 
achieved  through  the  work  of  Cole,  Dochez  and  others. 

Four  groups  or  strains  of  pneumococci  are  now  recognized.^  Being 
all  diplococci  they  can  be  difilerentiated  only  by  their  agglutination  re- 

V.  A.  M.  A.,  Feb.  23,  1889.    Med.  'News,  May  20,  1905. 

==  Dochez  and  Gillespie:     Jour.  A.  M.  A.,  1913,  LXT,   10,  p.  727. 


LOBAK    PI^EUMONIA  189 

actions  with  specific  sera,  except  Group  III,  which  is  morphologically 
characteristic. 

Group  I  is  the  cause  of  from  30  to  47  per  cenC.  of  all  cases  of  pneu- 
monia and  has  a  mortality  of  about  24  per  cent. 

Group  II  is  indistinguishable  from  Group  I  save  by  the  agglutination 
reaction.  It  is  found  in  from  18  to  39  per  cent,  of  cases  and  is  fatal  in 
about  60  per  cent,  of  cases  caused  by  it. 

Immune  sera  ^  produced  by  each  of  these  two  groups  liave  been 
obtained  from  horses  and  seem  to  have  specific  thera])eutic  value. 

Group  III  is  the  pneumococcus  mucosus/  formerly  classified  with  the 
streptococcus  mucosus.  It  has  a  distinct  mucoid  capsule  and  produces 
an  abundant,  stringy  mucous  growth  on  surface  colonies.  It  is  the  cause, 
of  from  8  to  13  per  cent,  of  all  pneumonia  and  is  fatal  in  about  61  per 
cent,  of  cases. 

Group  IV  comprises  a  heterogeneous  lot  of  pneumococci  not  classified 
with  Groups  I,  II,  or  III.  Each  strain  of  cocci  in  this  group  produces  a 
specific  agglutinin  for  itself,  which  does  not  agglutinate  the  other  strains 
or  groups.  This  is  the  type  ordinarily  found  in  normal  mouths.  These 
organisms  are  of  low  virulence,  cause  about  20  per  cent,  of  cases,  and 
have  a  mortality  of  only  about  7  per  cent. 

These  four  groups  seem  quite  stable  and  show  no  tendency  to  muta- 
tion. 

The  pneumococci  of  the  first  three  groups  cause  about  80  per  cent,  of 
all  cases  of  pneumonia  and  occur  only  in  the  mouths  of  people  recover- 
ing from  the  disease  or  of  those  in  direct  contact  with  such  cases.^  In 
other  words,  pneumonia  is  a  contact  disease  in  at  least  80  per  cent,  of 
cases,  the  infection  being  obtained  from  a  patient  or  carrier. 

Modes  of  Transmission. — The  pneumococcus  leaves  the  mouth  mainly 
in  the  discharges  from  the  mouth  and  nose,  and  enters  the  system  through 
the  same  channels.  The  infection  is  spread  directly  and  indirectly 
through  the  great  variety  of  ways  discussed  under  diphtheria  and  tuber- 
culosis. Indirect  transmission  through  cups,  thermometers,  handker- 
chiefs, and  other  objects  contaminated  with  the  fresh  discharges  may 
occur ;  and  droplet  infection  also  comes  into  consideration. 

Resistance  of  the  Virus. — The  pneumococcus  is  a  frail  organism;  it 
does  not  multiply  in  nature  outside  of  the  body  and  indirect  trans- 
mission is  not  likely  except  with  fresh  infectious  material.  Even  upon 
artificial  culture  media  the  life  of  the  pneumococcus  is  brief;  it  must 
be  transplanted  frequently  in  order  to  keep  it  alive;  it  is  customary  in 
laboratories  to  pass  it  through  a  susceptible  animal,  such  as  a  mouse  or 
rabbit,  from  time  to  time,  in  order  to  maintain  its  virulence, 

>Cole:      Arch.  Tnt.  Med.,  1914.  XTV,  1,  p.  56. 

'Hanes:      Jour.  Exp.   J\Jed..   1914,   XIX,    1.   p.   38. 

"Doehez  and  Averv:     Jour.  Exp.  Med.,  191.5,  XXII,  2,  p.   105. 


190      DISEASES    SPEEAD   THROUGH   MOUTH   AND   NOSE 

The  pneumococcus  is  readily  destroyed  by  heat;  52°  C.  for  10  min- 
utes is  sufficient.  On  the  other  hand,  it  withstands  low  temperatures 
very  well.  The  ordinary  germicidal  agents  destroy  it  quickly  and  with 
certainty.  It  may  live  for  months  in  dried  sputum,  in  which  it  also 
maintains  its  virulence. 

Immuiiity. — One  attack  of  pneumonia  does  not  leave  an  immunity. 
In  fact,  one  attack  predisposes  to  subsequent  attacks,  as  is  the  case  with 
erysipelas  and  rheumatic  fever.  Man,  however,  must  possess  a  certain 
degree  of  resistance  to  the  pneumococcus,  else  the  disease  would  be 
even  more  prevalent  than  it  is,  and  recovery  would  probably  be  less  fre- 
quent. 

The  mechanism  of  the  immunity  to  this  infection  is  not  at  all  un- 
derstood. Phagocytosis  may  play  a  prominent,  perhaps  a  dominant, 
role.  Protective  antibodies,  rather  feeble,  have  been  found  in  the  blood 
serum  of  immunized  animals,  and  also  in  the  blood  serum  of  persons 
M^ho  have  recovered  from  pneumonia.  The  pneumococcic  attack,  espe- 
cially the  crisis,  resembles  an  anaphylactic  reaction,  and,  while  the 
mechanism  of  immunity  in  this  infection  is  probably  complex,  the  best 
explanation  of  it  at  present  is  in  terms  of  anaphylaxis. 

Many  weakening  diseases  diminish  resistance  to  the  pneumococcus. 
Pneumonia  is  frequent  in  alcoholics,  and  is  commonly  brought  on  by 
exposure  to  cold,  to  trauma,  or  to  local  irritation.  It  is  a  frequent 
complication  of  typhoid  fever,  influenza,  Bright's  disease,  and  other  de- 
bilitating affections.  Old  age,  as  well  as  other  enfeebling  conditions, 
may  act  as  a  predisposing  cause  by  lowering  immunity.  Other  factors 
which  predispose  to  pneumonia  are  sudden  changes  in  temperature, 
trauma,  irritation  caused  by  aspiration  of  foreign  substances,  or  the  in- 
halation of  dust  or  irritating  vapors. 

It  should  be  remembered  that  pneumonia,  like  other  communicable 
infections,  frequently  attacks  the  strong  and  robust. 

The  pneumococcus  is  particularly  virulent  when  it  attacks  races  in 
which  the  disease  has  not  been  prevalent.  This  was  the  case  with  the 
laborers  on  the  Panama  Canal  and  the  miners  on  the  Eand.  Such  cir- 
cumstances indicate  that  a  certain  amount  of  racial  resistance  is  acquired 
through  long  conflict  with  the  pneumococcus. 

Prevention. — The  prevention  of  pneumonia  must  be  based  upon  gen- 
eral principles  guided  by  analogy  from  similar  infections.  As  long  as 
we  are  ignorant  of  the  fundamental  factors  concerned  in  the  etiology 
and  pathogenesis  of  the  disease,  our  preventive  measures  must  lack  pre- 
cision. 

The  virulent  pneumococcus  should  not  be  lightly  regarded  as  a  nor- 
mal inhabitant  of  the  mouth,  throat,  and  nose.  Because  the  pneumo- 
coccus is  very  widely  spread  and  the  disease  is  ubiquitous,  and  because 
the  associated  factors  which  determine  infection  seem  complicated  and 


LOBAR    PNEUMONIA  191 

not  well  understood,  are  not  sufficient  excuses  for  a  supine  and  hope- 
less attitude.  The  problem  of  tuberculosis  has  been  attacked  with  vigor 
with  scarcely  better  understanding  of  the  fundamental  problems  at 
issue.  Each  case  of  pneumonia  should  be  regarded  as  a  focus  for  the 
spread  of  the  infection.  Ultimate  control  of  the  disease  will  probably 
have  to  await  the  discovery  of  a  specific  prophylactic  and  the  recognition 
of  dangerous  carriers.  Meanwhile  we  should  think  of  pneumonia  very 
much  as  we  think  of  whooping-cough  and  influenza,  as  an  infection 
which  is  spread  from  man  to  man  through  the  secretions  of  the  mouth 
and  nose.  It  is  true  that  pneumococci  are  frequently  found  in  the 
buccal  secretions  of  healthy  persons.  Sternberg  in  1880  first  demon- 
strated the  pneumococcus  in  his  own  saliva.  ISTetter  found  it  in  20  per 
cent,  of  the  persons  whom  he  examined,  and  the  New  York  Commission 
reported  its  presence  in  from  48  to  85  per  cent.  In  other  words,  many 
persons  are  pneumococcus  carriers.  However,  there  are  at  least  four 
different  strains  of  the  pneumococcus,  which  vary  greatly  in  pathogenic 
power.  A  somewhat  analogous  situation  is  noted  in  the  diphtheria-like 
organisms  in  the  throats  of  about  1  per  cent,  of  all  healthy  individuals. 
The  findings  of  the  Medical  Commission  for  the  Investigation  of  Acute 
Eespiratory  Diseases  seem  to  make  prevention  a  less  hopeless  task  than 
at  first  sight  appears  possible  from  the  widespread  distribution  of  the 
pneumococcus.  It  was  shown  that,  while  a  number  of  individuals  con- 
stantly harbor  virulent  strains  of  the  pneumococci  in  their  mouths,  the 
majority  of  people  do  so  only  from  time  to  time.  Individuals  who  come 
in  contact  with  pneumonia  patients  are  more  apt  to  harbor  the  pneumo- 
coccus than  those  not  so  exposed.  Patients  convalescent  from  pneu- 
monia may  carry  virulent  organisms  in  their  respiratory  passages  for 
weeks  or  even  months.  We  now  know  that  the  ordinary  pneumococcus 
carrier  harbors  Group  IV,  which  is  the  least  virulent.  Healthy  persons 
carry  the  virulent  types  only  when  in  close  association  with  the 
disease. 

Pneumonia  should  be  added  to  the  list  of  diseases  requiring  com- 
pulsory notification.  Cases  should  be  isolated  at  least  in  the  same  sense 
that  diphtheria  is  isolated — the  discharges  from  the  nose  and  throat 
should  be  burned  or  disinfected.  If  the  patient  is  treated  at  home,  the 
house  should  be  placarded  in  order  to  discourage  visiting  and  as  an 
educational  measure. 

There  is  no  specific  prophylaxis  for  pneumonia.  Prevention  con- 
sists in  avoiding  the  infection,  sustaining  the  tone  of  the  machine,  care 
and  cleanliness  of  the  upper  respiratory  passages,  avoiding  chills,  expo- 
sure, and  other  predisposing  causes,  and  especially  avoiding  living  in 
stuffy,  ill-ventilated  rooms  and  dusty  atmospheres. 

As  carriers  doubtless  play  an  important  role  in  disseminating  this 
infection,  the  education  of  the  public  concerning  certain  sanitary  habits 


192      ])ISEASK8    SPREAI)   THROUGH   MOUTH   AND   NOSE 

should  be  actively  continued.  These  include  the  danger  of  spitting 
promiscuously  and  of  kissing;  the  proper  care  to  he  exercised  in  sneezing 
and  coughing;  the  peril  in  the  common  drinking  cup,  the  roller  towel; 
and  the  habit  of  placing  unnecessary  things  in  the  mouth. 

It  should  become  common  knowledge  that  anything  which  tends  to 
reduce  vitality  predisposes  to  pneumonia,  such  as  dissipation,  loss  of 
sleep,  overwork,  worry,  poor  or  insufficient  food,  lack  of  exercise,  al- 
cohol, colds,  or  excesses  of  all  kinds;  the  atonic  effect  of  living  in  over- 
heated rooms,  and  the  injurious  effect  of  excessively  dried  and  warmed 
air,  and  sleeping  in  warmed  rooms.  Cold  baths,  regulation  of  tempera- 
ture and  ventilation,  sleeping  with  open  windows  or  in  the  open  air, 
as  well  as  oral  hygiene,  are  useful  prophylactic  measures  for  pneumonia 
as  well  as  tuberculosis,  "colds,"  and  a  large  group  of  diseases. 

Upon  the  Isthmus  of  Panama  pneumonia  was  unduly  prevalent  ow- 
ing to  overcrowding,  which  favors  contact  infection.  The  same  was  found 
by  Colonel  Gorgas  among  the  workmen  of  the  African  mines.  The  pre- 
vention consisted  in  scattering  the  workmen,  giving  them  separate  homes 
in  place  of  barracks.  In  Chicago,  Evans  believes  that  the  prevalence  of 
pneumonia  was  influenced  by  better  ventilation  of  the  street  cars.  Allay- 
ing street  dust  and  house  dust  removes  one  of  the  predisposing  causes  of 
pneumonia  and  other  respiratory  infections. 

Health  officers  may  assist  in  the  cause  of  disseminating  knowledge 
concerning  the  disease  and  by  enforcing  antispitting  regulations,  by 
proper  cleansing  and  oiling  of  streets,  by  requiring  a  stricter  compliance 
with  building  and  housing  laws,  and  by  the  regulation  of  the  ventilation 
and  conditions  of  the  air  in  theaters,  schools,  street  cars,  and  public 
buildings,  as  well  as  the  crowding  of  such  places. 


INFLUENZA 

The  cause  of  influenza  is  assumed  to  be  a  small  bacillus  which  is 
constantly  associated  with  the  disease;  it  was  described  by  Pfeiffer  in 
1892  and  1893.^  Influenza  prevails  without  relation  to  climate,  wind, 
weather,  or  telluric  conditions.  It  occurs  sporadically,  in  epidemics  and 
in  great  pandemics.  In  1889  and  1890  influenza  spread  to  the  four 
quarters  of  the  globe,  and,  judged  by  the  morbidity  and  mortality,  this 
was  the  most  extensive  and  serious  pandemic  that  has  occurred  in  modern 
times.     These  worldwide  outbreaks  usually  spread  from  east  to  west. 

Immunity. — Immunity  to  influenza  is  slight;  in  fact,  one  attack 
seems  to  predispose  to  subsequent  attacks;  second  and  third  attacks  are 
common  as  a  result  of  new  infections  or  reinfections.  Influenza  bacil- 
lus carriers  are  numerous.     Males  and  the  robust  individuals  in  a  com- 

^Dentsch.  med.  Wochenschr.,  2,  1892,  p.  28.     Zeitschr.  f.  Hyg.,  XIII,  1893. 


INFLUENZA  193 

munity  seem  more  susceptible,  perhaps  on  account  of  greater  exposure. 

Modes  of  Transmission. — Influenza  is  spread  directly  from  person 
to  person.  It  is  highly  contagious  in  the  early  stages.  The  influenza 
bacillus  is  found  in  the  secretions  from  the  nose,  throat,  and  respira- 
tory tract.  The  bacillus  does  not  multiply  outside  the  body  and  has  a 
very  feeble  resistance.  It  grows  with  difficulty  upon  artificial  culture 
media  and  soon  dies  out;  therefore  "contact"  infection  or  the  use 
of  handkerchiefs,  towels,  cups,  and  other  objects  contaminated  with  the 
fresh  secretions  are  the  common  modes  of  transmission.  Influenza  is 
kept  alive  in  interepidemic  years  in  carriers.  Lord  found  the  bacillus 
influenza  in  25  to  59  per  cent,  of  all  cases  with  cough  and  expectoration 
in  an  interepidemic  period  in  Boston. 

Prophylaxis. — Prophylaxis  is  practically  the  same  as  for  all  other 
infections  transferred  by  the  secretions  from  the  mouth  and  nose.  Iso- 
lation is  not  always  practicable,  but  patients  for  their  own  good  as  well 
as  the  protection  of  others  should  remain  in  bed  during  the  febrile  stage. 
This  one  measure  would  very  largely  diminish  the  prevalence  of  influenza 
as  well  as  common  colds.  The  infection  could  be  kept  out  of  a  country 
by  strict  maritime  quarantine,  provided  mild  cases  and  carriers  could 
be  recognized;  this,  however,  is  not  practicable.  The  public  has  not 
sufficient  regard  for  influenza  to  tolerate  aggressive  measures.  The 
disease  may  frequently  be  avoided  by  individual  prophylaxis.  During 
epidemics  individuals  should  avoid  theaters,  mass  meetings,  closed  and 
crowded  cars,  and  close  contact  with  their  fellowmen,  especially  those  who 
have  catarrhal  symptoms.  It  is  quite  worth  while  to  isolate  the  first  case 
of  influenza  in  a  household  in  order  to  prevent  a  house  epidemic.  This 
may  be  done  on  precisely  parallel  lines  to  those  described  for  diphtheria. 
Influenza  is  especially  dangerous  when  complicating  pulmonary  tuber- 
culosis, and  care  should  be  taken  to  keep  it  out  of  sanitaria.  Even  dur- 
ing epidemics  influenza  may  successfully  be  kept  out  of  institutions  by 
an  intelligent  quarantine.  Once  within  the  walls,  it  is  exceedingly  diffi- 
cult to  control.  Persons  who  continually  carry  the  influenza  bacillus  in 
their  nose,  throat,  or  respiratory  tract  should  guard  against  exposure 
to  wet  and  cold  on  account  of  the  danger  of  reinfection.  Influenza  is 
another  one  of  those  diseases  the  control  of  which  rests  with  the  public. 
Education,  therefore,  is  of  prime  importance.  The  danger  from  the  use 
of  the  common  drinking-  cup,  the  roller  towel,  kissing,  droplet  infection, 
handkerchiefs,  pipes,  toys,  soda-water  glasses,  spoons,  and  other  ob- 
jects recently  mouthed  should  be  emphasized:  spitting  ordinances  en- 
forced, ventilation  and  overcrowding  of  street  cars  corrected,  and  dust 
allayed. 


194      DISEASES    SPKKAD   Til  K'Ol'CJH    MOUTH   AND   NOSE 


COMMON    COLDS 

More  people  probably  suffer  from  common  colds  than  from  any  other 
single  ailment.  Vital  statistics  give  no  hint  of  the  prevalence  and  im- 
portance of  these  minor  affections  because  the  mortality  is  nil  and  the 
morbidity  records  are  notoriously  imperfect  and  difficult  to  collect.  Could 
the  sum  total  of  suffering,  inconveniences,  sequelae,  and  economic  loss 
resulting  from  common  colds  be  obtained,  it  would  at  once  promote 
these  infections  from  the  trivial  into  the  rank  of  the  serious  diseases. 

The  common  colds  here  considered,  are  a  group  of  acute  infections  of 
the  mucous  membranes  of  the  nose,  pharynx,  tonsils,  larynx,  trachea,  or 
larger  bronchi.  A  common  cold  is  not  merely  a  congestion,  it  is  an 
infection. 

Congestion  and  inflammation  of  the  mucous  membrane  of  the  up- 
per respiratory  tract  frequently  occur  as  a  result  of  irritants  other  than 
bacteria.  Thus,  chemical  and  mechanical  irritants  will  produce  a  con- 
gestion or  inflammation;  an  increased  acidity  causes  a  flaring  up  of 
the  mucous  membranes,  especially  of  the  nose;  and  many  other  local 
and  reflex  causes  lead  to  acute  or  chronic  catarrhal  conditions  of  these 
membranes,  which  may  become  exquisitely  sensitive  and  sometimes  hyper- 
susceptible.  In  the  absence  of  the  proper  microorganism,  however,  these 
conditions  do  not  develop  into  infectious  colds,  and  are,  therefore,  not 
communicable. 

The  popular  fallacy  of  colds  being  due  to  exposure  to  drafts,  sud- 
den changes  of  temperature,  and  chilling  of  the  body  clings  persistently 
in  both  the  professional  and  lay  mind.  These  are  predisposing  causes 
and  will  not  produce  a  cold  without  the  presence  of  the  specific  cause. 
The  bacteria  usually  found  associated  with  these  catarrhal  infections  are : 
staphylococci,  streptococci,  pneumococci,  influenza  bacillus,  the  Gram  neg- 
ative cocci  classed  together  as  members  is  of  the  micrococcus  catarrhalis 
group,  diphtheroid  bacilli.  Bacillus  catarrhalis,  and  other  microorgan- 
isms. The  etiological  relationship  between  these  organisms  and  the 
disease  is  not  always  clear.^  Many  of  the  above-mentioned  bacteria  are 
also  found  normally  upon  the  mucous  membranes  of  the  nose,  mouth, 
throat,  and  upper  respiratory  passages;  reinfections  must,  therefore,  be 
common,  and  predisposing  factors  which  diminish  resistance  have  a 
special  importance.  Common  colds  frequently  attack  the  strong  and 
robust  if  exposed. 

^  Foster,  working  in  my  laboratory,  has  just  confirmed  and  extended  Kruse's 
observations,  showing  tlie  presence  of  a  filtrable  virus  in  the  secretions  from 
the  nose  in  common  colds.  Tliis  filtrate,  as  well  as  subcultures  grown  in  selective 
media,  when  dropped  into  tlie  nostril  of  healtliy  persons,  produces  a  cold.  (J.  A. 
M.  A.,  April  8,  1916,  Vol.  LXVI,  No.  14.)  There  are  different  types  of  colds,  due 
to  different  viruses,  or  to  the  associated  bacteria. 


COMMON    COLDS  195 

Colds  are  contracted  from  other  persons  having  colds,  just  as  diph- 
theria is  contracted  from  diphtheria.  Arctic  explorers  exposed  to  all 
the  conditions  ordinarily  supposed  to  produce  colds  do  not  suffer  from 
these  ailments  until  they  return  to  civilization  and  become  reinfected 
by  contact  with  their  fellowmen.  A  campaign  to  prevent  the  spread 
of  the  common  cold  would  have  much  collateral  good  in  aiding  the 
suppression  of  tuberculosis  and  causing  a  diminution  of  pneumonia  and 
other  infections.  Common  colds  occur  in  epidemics  and  have  all  the 
earmarks  of  a  contagious  disease.  Colds  are  apt  to  go  through  all  the 
members  of  a  household,  and  outbreaks  in  schools,  factories,  and  other 
places  where  people  are  closely  associated  frequently  occur  and  result  in 
considerable  loss  of  time  and  money. 

While  common  colds  are  never  fatal,  the  complications  and  sequelae 
are  serious.  These  are :  rheumatic  fever,  pneumonia,  sinusitis,  nephritis, 
and  a  depressed  vitality  which  favors  other  infections  and  hastens  the 
progress  of  organic  diseases. 

Common  colds  are  perhaps  most  contagious  during  the  early  stages. 
If  persons  would  isolate  themselves  by  remaining  in  bed  during  the 
first  three  days  of  a  cold,  they  would  not  only  benefit  themselves,  but 
would  largely  prevent  the  spread  of  the  infection.  The  contagiousness 
and  severity  of  colds  vary  greatly  in  different  epidemics  and  in  dif- 
ferent seasons  of  the  year,  depending  upon  the  particular  microorganism 
involved  and  other  factors  not  well  understood. 

Prevention. — The  prevention  of  colds  consists,  first,  in  avoiding  the 
infection,  and,  secondly,  in  guarding  against  the  predisposing  causes. 
Contact  should  be  avoided  with  persons  who  have  colds,  especially  in 
street  cars,  offices,  and  other  poorly  ventilated  spaces  where  the  risk  of 
persons  coughing  or  sneezing  directly  in  one's  face  is  imminent.  Con- 
tact with  the  infection  may  further  be  guarded  against  by  a  careful 
self-education  in  sanitary  habits  and  cleanliness  based  upon  the  modern 
conception  of  contact  infection. 

Colds,  like  other  diseases  conveyed  in  the  secretions  from  the  nose 
and  mouth,  are  often  conveyed  by  direct  and  indirect  contact  through 
lack  of  hygienic  cleanliness  and  a  disregard  of  sanitary  habits.  Kissing, 
the  common  drinking  cup,  the  roller  towel,  pipes,  toys,  pencils,  fingers, 
food,  and  other  objects  contaminated  with  the  fresh  secretions  will 
transmit  the  disease. 

The  predisposing  causes  of  colds  include  a  number  of  conditions  that 
depress  vitality  and  thereby  diminish  resistance.  The  mechanism  by 
which  immunity  is  lessened  is  discussed  on  page  403.  The  principal 
predisposing  factors  in  "catching"  cold  are:  vitiated  air,  dust,  drafts, 
sudden  changes  of  temperature,  exposure  to  cold  and  wet,  overwork, 
loss  of  sleep  or  insufficient  rest,  improper  food,  and  other  conditions  that 
lower  the  general  vitalitv  of  the  bodv-     On  the  other  hand,  it  must  be 


196     DISEASES   SPEEAD   THEOUGH   MOUTH   AND   NOSE 

clearly  kept  in  miiul  that  vigorous  persons  in  prime  health  will  contract 
a  cold  if  they  receive  the  infection. 

A  special  word  concerning  drafts  is  necessary.  Drafts  in  them- 
selves cannot  produce  an  infectious  cold.  The  first  symptom  of  the 
disease  is  a  chill,  which  is  not  the  cause,  but  the  effect,  of  the  infec- 
tion. It  is  a  common  belief  that  the  cold  is  caught  when  the  chill 
occurs.  The  rigor  frequently  consists  of  only  a  transient  chilliness,  and 
it  is  during  this  time  that  the  individual  thinks  he  feels  a  draft  which 
is  producing  his  cold.     (See  page  686.) 

Drafts  have  no  appreciable  injurious  effect  upon  persons  in  good 
physical  tone.  They  are,  however,  injurious  to  infants,  the  aged,  and 
to  susceptible  individuals.  Drafts  are  particularly  apt  to  harm  persons 
accustomed  only  to  still,  warm  air.  "It  is  not  the  engine  drivers  and 
firemen  of  trains  that  catch  colds,  but  the  passengers  in  the  stuffy  car- 
riages." Coddling  renders  one  susceptible  to  drafts,  partly  for  the  reason 
that  the  vasomotor  impulses  which  contract  the  blood  vessels  of  the 
skin  are  not  sent  out  by  the  nervous  mechanism,  and  consequently  undue 
cooling  of  the  part  blown  upon,  and  perhaps  of  the  blood  itself,  takes 
place.  Normally,  when  the  wind  blows  upon  the  skin  the  vasomotor 
contraction  reduces  the  supply  of  blood  and  the  tendency  to  cooling  is 
further  met  by  a  stimulus  which  increases  heat  production.  While  it  is 
true  that  a  draft  can  no  more  cause  an  infectious  cold  than  it  can  cause 
diphtheria,  nevertheless,  it  is  true  that  a  draft  may  increase  the  severity 
of  a  cold  or  be  the  predisposing  cause  by  which  immunity  is  lowered. 

It  is  a  mistake  to  think  that  the  skin  alone  is  involved  in  the  ques- 
tion of  drafts.  The  hardening  of  the  skin  as  a  prevention  of  colds  is, 
therefore,  a  misnomer.  The  good  effects  of  cold  baths,  exercise,  fresh 
air,  sunlight,  and  wholesome  food  do  not  consist  in  'Tiardening^'  the 
skin,  but  in  improving  the  nutrition,  stimulating  the  metabolism,  help- 
ing the  control  of  the  nervous  system,  improving  the  tone  of  the  vaso- 
motor system,  strengthening  the  musculature,  and  enriching  the 
blood. 

In  preventing  the  ill  effects  of  drafts,  therefore,  the  entire  organiza- 
tion of  the  body  must  be  considered,  and  not  the  skin  alone. 

Other  important  predisposing  factors  to  colds  are  mechanical  defects 
in  breathing,  or  the  filtering  power  of  the  upper  respiratory  passages,  also 
local  pathological  conditions,  such  as  adenoids,  polypus,  enlarged  tonsils, 
deviation  of  the  septum,  chronic  catarrhal  conditions,  all  of  which  should 
receive  appropriate  treatment. 

One  of  the  most  important  predisposing  factors  to  cold  is  breathing 
vitiated  and  dusty  air.  Good  ventilation,  therefore,  with  air  not  too 
dry  nor  too  warm,  and  the  allaying  of  dust  would  prevent  many  a  cold. 
The  bacteria  accompanying  colds  are  frequently  found  in  the  mouth, 
nose,  throat  and  teeth  of  persons  in  good  health.    Cleanliness  and  care  of 


CEEEBEOSPINAL    FEVER  197 

these  parts  is',  therefore,  an  important  consideration  in  the  prevention  of 
the  complications  of  common  colds. 


CEREBROSPINAL   FEVER 

Cerebrospinal  fever  is  an  infection  with  the  meningococcus  {Diplo- 
coccus  intracellularis  meningitidis,  Weichselbaum) .  The  essential  lesions 
of  the  disease  are  chiefly  focused  upon  the  meninges  of  the  brain  and 
cord.    The  disease  occurs  both  in  localized  epidemics  and  sporadically. 

The  meningococcus  is  a  frail  microorganism,  closely  resembling  the 
gonococcus.  Both  are  biscuit-shaped  cocci ;  both  grow  feebly  on  artificial 
media.  They  are  readily  killed  by  drying,  sunlight,  heat,  and  other  un- 
favorable conditions.  They  live  a  strict  parasitic  existence  and  cause 
diseases  peculiar  to  man,  with  lesions  which  resemble  each  other,  both 
as  far  as  the  character  of  the  inflammation  and  the  distribution  of  the 
cocci  within  and  without  the  cells  are  concerned.  As  a  rule,  these  two 
microorganisms  are  usually  distinguished  by  the  source  frum  which  they 
are  obtained.  Otherwise  the  difi^erentiation  is  difficult  and  depends  upon 
careful  cultural  and  biological  studies. 

All  cases  of  meningitis  are  not  caused  by  the  meningococcus.  Spo- 
radic cases  may  be  due  to  the  pneumococcus,  streptococcus,  bacillus  of 
influenza,  the  colon  bacillus,  the  typhoid  bacillus,  the  bacillus  of  bubonic 
plague,  and  of  glanders.  The  gonococcus  may  also  cause  meningitis  as 
a  secondary  complication.  The  epidemic  form  of  cerebrospinal  menin- 
gitis is  always  due  to  the  meningococcus.  Only  one  epidemic  so  far 
studied  bacteriologically  was  certainly  not  due  to  the  meningococcus;  in 
this  the  microorganism  responsible  seems  to  have  been  the  Streptococcus 
mucosus,  or  a  close  relative. 

The  first  epidemic  outbreak  of  meningitis  was  reported  by  Vieus- 
seux  in  Geneva  in  1805.  The  next  year  James  Jackson,  Thomas  Welch, 
and  J.  C.  Warren  investigated  an  outbreak  in  Massachusetts.  Since  then 
numerous  epidemics  have  occurred.  In  New  York  in  1904-05  there  were 
6,755  cases  and  3,455  deaths. 

The  epidemiology  of  cerebrospinal  fever  differs  from  that  of  infantile 
paralysis  in  several  aspects.  The  seasonal  prevalence  of  infantile  paral- 
ysis follows  the  curve  of  the  summer  diarrheas  (July  to  September), 
while  cerebrospinal  fever  prevails  especially  in  the  fall  and  winter 
months.  The  seasonal  prevalence  of  cerebrospinal  fever  is  strikingly 
similar  to  that  of  pneumonia  and  influenza,  and  corresponds  to  a  num- 
ber of  diseases,  such  as  scarlet  fever,  measles,  diphtheria,  and  smallpox, 
in  which  the  principal  mode  of  infection  is  believed  to  be  through  the 
respiratory  tract,  and  which  are  supposed  to  be  spread  mainly  by  con- 
tact. 


198      DISEASES   SPREAD   THROUGH   MOUTH   AND   NOSE 

The  epidemics  are  usually  localized.  Couutry  districts  are  more 
afflicted  than  cities.  Children  and  young  adults  are  most  susceptible. 
Outbreaks  sometimes  occur  in  camp  or  on  shipboard.  The  immunity 
produced  by  one  attack  is  not  lasting.  Councilman  reports  five  instances 
in  which  the  same  individual  is  reported  to  have  had  the  disease  twice. 

It  is  probable  that  the  meningococcus  enters  the  system  through  the 
mucous  membrane  of  the  nasopharynx.  From  this  position  it  may  reach 
the  meninges  directly  through  the  lymph  channels  or  indirectly  through 
the  circulation.  The  experiments  of  Flexner  in  the  monkey  indicate  that 
when  the  meningococcus  is  introduced  into  the  cerebral  cavity  it  escapes 
by  a  reversed  lymphatic  current,  so  that  under  these  circumstances  it  may 
be  found  in  the  mucous  membrane  of  the  nasopharynx.  Fliigge,  Weich- 
selbaum,  Scheurer,  and  others  have  found  the  meningococcus  present 
in  great  numbers  in  the  nose  and  pharynx  in  most  cases  of  the  disease 
during  the  first  12  days  of  illness.  Park  states  that  after  the  14th 
day  they  cannot  usually  be  found.  The  admirable  monograph  of  Elser 
and  Huntoon  ^  includes  a  careful  study  of  210  cases  of  the  disease.  The 
most  striking  conclusion  by  these  authors  is  the  essential  importance 
of  meningococcus  carriers  in  the  transmission  of  epidemic  meningitis. 
The  number  of  persons  who  become  such  carriers  during  an  epidemic 
of  meningitis  is  far  greater  than  the  number  of  cases  of  actual  menin- 
gitis. Perhaps  70  per  cent,  of  healthy  persons  exposed  may  harbor  menin- 
gococci in  the  respiratory  passages.  Carriers  exceed  the  number  of  cases 
in  the  proportion  of  ten  to  one.  Apart  from  epidemics  the  meningococcus 
can  be  found  but  rarely  in  healthy  individuals,  but  apparently  there  are 
persons  who,  once  harboring  this  organism  in  the  nasopharynx,  carry  it 
permanently  and  thus  perpetuate  the  disease. 

Meyer,  Voltmann,  Furst,  and  Grieber  ^  studied  the  question  of  car- 
riers in  cerebrospinal  meningitis.  They  found  1.73  per  cent,  of  menin- 
gococcus carriers  in  over  9,111  healthy  soldiers  in  the  Munich  garrison 
at  a  time  when  no  cerebrospinal  fever  was  present.  One  examination 
was  made  from  each  soldier.  A  special  study  was  made  of  1,911  healthy 
persons  who  were  examined  many  times,  with  the  result  that  2.46  per 
cent,  were  found  to  be  meningococcus  carriers.  Of  the  total  of  11,022 
healthy  persons,  about  2  per  cent,  examined  contained  the  meningococcus 
in  their  throats.  Isolation  of  the  carriers  had  no  influence  on  the  inci- 
dence of  the  disease,  and  epidemiologically  they  found  only  exceptional 
relationship  between  the  carriers  and  the  sick.  In  one  of  the  years  during 
this  study  numerous  clinical  cases  occurred;  in  another  year  none,  al- 
though the  number  of  carriers  remained  the  same  both  years.  The 
authors  conclude  that  extreme  painstaking  cultural  detection  of  meningo- 
coccus carriers  is  unnecessary  in  combating  the  spread  of  cerebrospinal 

^Journal  of  Medical  Research,  1909,  Vol.  XX,  pp.  377-536. 
^  Munchener  med.  Wochensch.,  1910,  No.  30,  July  26. 


CEEEBROSPINAL    FEVER  199 

meningitis;  that  the  practical  benefits  do  not  justify  the  care  and  time 
necessary  for  such  work.  They  believe  that  the  chief  foci,  aside  from 
factors  not  understood  in  the  spread  of  this  disease,  seem  to  be  the  sick 
and  especially  the  mild  cases.  Great  ciare  should,  therefore,  be  taken 
to  isolate  the  mild  ease  so  as  to  diminish  the  number  of  carriers.  On 
the  other  hand,  in  the  epidemic  of  cerebrospinal  meningitis  in  Texas  in 
1912,  Thayer  examined  421  persons;  59.6  per  cent,  were  healthy  carriers, 
as  determined  by  the  examination  of  stained  smears.  The  results  ob- 
tained from  cultures  showed  53.75  per  cent,  to  be  positive.  It  is  now 
believed  that  cerebrospinal  meningitis  is  transmitted  principally  through 
the  medium  of  healthy  carriers.  Only  a  small  percentage  of  the  carriers 
develop  the  disease. 

The  occurrence  of  more  than  one  case  of  the  disease  in  families  is  com- 
mon. In  the  recent  Texas  epidemic  there  were  many  instances  in  which 
two  members  developed  the  disease,  and  in  a  smaller  number  three, 
four,  and  five  members  became  infected.  The  disease  is  undoubtedly  trans- 
mitted rather  directly  from  person  to  person,  for  the  meningococcus  is 
of  such  low  vitality  that  it  succumbs  quickly  to  drying,  sunlight,  and 
other  injurious  influences.  On  account  of  its  severity,  persons  suffering 
from  the  disease  are  decidedly  limited  in  their  sphere  of  influence,  and, 
as  only  a  very  small  proportion  of  those  who  receive  the  microorganism 
are  susceptible  to  it,  the  perpetuation  and  spread  of  meningitis  must 
depend  on  the  healthy  carriers  who  pass  the  meningococcus  on  from  one 
to  another  until  a  susceptible  individual  is  infected  and  develops  meningi- 
tis.   The  virulence  of  the  organism  is  also  a  determining  factor. 

Preventian. — From  our  present  knowledge  preventive  measures  are 
clearly  indicated,  though  very  difficult  to  carry  out.  Epidemic  cerebro- 
spinal meningitis  is  a  good  example  of  a  group  of  diseases  in  which  a 
more  precise  knowledge  of  the  modes  of  transmission  of  the  disease 
makes  it  obvious  that  prevention  is  a  matter  of  extreme  practical  diffi- 
culty. Flugge  estimates  that  healthy  carriers  of  this  disease  are  ten 
times  more  numerous  than  recognized  cases,  and,  therefore,  are  more 
than  ten  times  as  prolific  a  source  of  infection.  While  the  isolation 
of  the  known  cases  will  prevent  a  certain  number  of  secondary  cases, 
this  measure  alone  cannot  hope  to  control  the  disease.  It  is  obviously 
impractical  to  undertake  to  make  bacteriological  examinations  sufficient 
to  discover  all  the  carriers  in  a  community  of  any  considerable  size; 
moreover,  the  control  of  so  many  carriers  when  discovered  would  re- 
quire military  rule.  We  must  frankly  admit  that  when  cerebrospinal 
meningitis  has  once  become  epidemic  it  cannot  be  stamped  out  by  any 
known  means  of  practical  application. 

This  does  not  mean  that  we  should  assume  a  supine  attitude,  for, 
even  though  the  disease  cannot  be  satisfactorily  controlled,  a  certain 
number  of  secondary  cases  can  be  prevented.    Every  case  and  every  sus- 


200      DISEASES   SPEEAD   THROUGH   MOUTH   AND   NOSE 

pected  case  should  at  once  be  reported  to  the  health  authorities  and 
the  patient  isolated.  The  virus  is  contained  especially  in  the  discharges 
of  the  mouth  and  nose,  and  these  secretions  should  be  disinfected.  The 
house  should  be  placarded,  visiting  prohibited,  and  isolation  practiced. 
These  measures  will  help  diminish  the  number  of  carriers. 

Personal  prophylaxis  consists  in  avoiding  the  infection  so  far  as 
possible,  and  in  the  use  of  antiseptic  gargles  and  nasal  douches.  When 
the  disease  is  epidemic  people  should  keep  Siwaj  from  large  public  gath- 
erings, crowded  street  cars,  avoid  the  use  of  public  drinking  cups,  and 
the  like.  They  should  be  advised  to  exercise  more  than  the  usual  care 
as  to  personal  cleanliness  and  oral  prophylaxis.  The  closing  of  the 
schools  may,  under  certain  circumstances,  be  justified.  Urotropin  in 
moderate  doses  has  been  suggested  as  a  possible,  though  quite  unproven, 
prophylactic. 

While  rigid  quarantine  is  not,  as  a  rule,  effective  in  controlling  this 
disease,  localized  outbreaks  in  institutions,  military  camps,  or  small 
towns  may  be  kept  from  spreading  by  a  strict  system  of  isolation,  even 
with  a  military  cordon. 

Antimeningitis  serum  is  useful  in  the  treatment  of  the  disease;  it 
is  not  practical  as  a  preventive.  It  must  be  introduced  into  the  subdural 
space  by  lumbar  puncture.  The  serum  should  be  provided  free  of  cost 
or  at  a  minimum  price  by  health  authorities.  Further,  boards  of  health 
should  provide  laboratory  facilities  for  the  bacteriological  diagnosis  of 
the  disease,  and  the  recognition  of  carriers. 

Sophian  and  Black  ^  recommend  an  active  immunization  induced  by 
inoculating  killed  cultures  of  the  meningococcus.  The  cultures  are 
grown  on  2  per  cent,  glucose  agar,  and  after  18  hours'  growth  are  washed 
off  in  distilled  water,  shaken  for  20  minutes,  heated  at  50°  C.  for  1  hour, 
and  tested  for  sterility.  One  million  bacteria  are  injected  at  the  first 
dose,  7  days  later  the  same  number,  and  7  days  later  2,000,000.  The 
injection  of  the  dead  meningococcus  confers  a  considerable  immunity, 
and  may  prove  to  be  a  valuable  measure  for  personal  prophylaxis. 
Chronic  carriers  should  be  inoculated  with  the  killed  cultures,  and  their 
sphere  of  activity  should  be  restricted.  Ftirthermore,  they  should  be 
impressed  with  the  danger  to  their  fellowmen,  and  given  careful  in- 
structions concerning  spitting,  sneezing,  coughing;  the  care  of  fomites, 
such  as  handkerchiefs,  spoons,  cups,  etc. ;  and  the  importance  of  cleanli- 
ness of  the  teeth,  mouth,  nose,  and  throat. 

V.  A.  M.  A.,  Aug.  17,  1912,  LIX,  7,  p.  527,  and  LXIII,  24,  Dec.  12,  1914,  p. 
2126. 


CHAPTEE   IV 
INSECT-BOKNE  DISEASES 

GENERAL    CONSIDERATIONS 

The  fact  that  disease  may  be  transmitted  through  the  bites  of  in- 
sects was  suspected  for  years,  but  it  was  not  until  1893  that  it  was 
demonstrated  as  a  new  principle  by  Theobald  Smith  in  the  case  of 
Texas  fever  of  cattle  and  the  tick.^  Since  then  many  diseases  have 
been  added  to  the  list,  which  is  constantly  growing.  We  now  know 
that  some  diseases  are  always  transmitted  through  insects  and  others 
occasionally.  A  thorough  comprehension  of  the  subject  is  necessary  for 
sanitarians  and  others  in  the  fight  against  disease  in  all  climates  and 
in  all  places. 

It  may  be  stated  as  a  general  law  that,  if  a  period  of  incubation 
in  the  insect  is  necessary,  it  indicates  that  the  parasite  probably  be- 
longs to  the  animal  kingdom  and  passes  part  of  its  life  cycle  within 
the  insect.  This  constitutes  the  so-called  extrinsic  period  of  incubation. 
Malaria  and  yellow  fever  are  examples  of  this  class,  which  is  spoken 
of  as  biological  transmission.  If,  on  the  other  hand,  insects  convey 
infection  at  once  without  a  period  of  incubation  in  the  insect,  the  trans- 
fer is  a  mechanical  one;  in  this  case  the  insect  does  not  play  the  part 
of  an  intermediate  host  in  the  true  biological  sense,  and  there  is  no 
cycle  of  development  of  the  parasite  within  the  insect.  These  cases 
are  almost  all  bacterial  infections. 

It  may  be  stated  as  a  general  rule  that  the  insect  hosts  are  not 
harmed  by  the  parasites  which  they  harbor  and  which  are  pathogenic 
for  man.  Thus,  the  malarial  protozoon  is  pathogenic  for  man,  but  a 
saprophyte  for  the  mosquito.  The  same  is  true  of  yellow  fever  and 
the  Stegomyia,  Texas  fever  and  the  tick,  plague  and  the  flea,  sleeping 
sickness  and  the  tsetse  fly,  typhoid  and  the  house  fly,  typhus  fever  and 
the  louse,  etc. 

The  intermediate  host  in  the  zoological  sense  is  that  animal  which 

harbors  the  asexual  phase  of  the  life  cycle  of  the  parasite;  the  definitive 

host  is  the  animal  which  harbors  the  sexual  phase.     Thus,  in  malaria 

man  is  the   intermediate  host,   the  mosquito   the   definitive   host.      In 

^The  other  names  associated  with  the  early  work  upon  insects  and  their  re- 
lation to  disease  are:  Maiison,  Finlay,  Ross,  Grassi,  and  the  U.  S.  Army  Com- 
mission— Reed,  Carroll,  Lazear,  and  Agramonte. 

201 


202  INSECT-BORNE    DISEASES 

popular  parlance,  the  insects  are  spoken  of  as  the  intermediate  hosts  in 
all  cases. 

Insects  transfer  infections  mechanically  in  a  variety  of  ways.  The 
mouth  parts,  legs,  or  outer  surfaces  of  the  body  may  be  smeared  with 
the  virus,  which  is  thus  simply  carried  to  the  lips,  iingers  or  food,  and 
thus  enter  the  susceptible  individual;  or  the  virus  may  remain  attached 
to  the  proboscis  of  a  biting  insect,  thus  transferring  the  infection  very 
much  as  a  hypodermic  syringe  would;  or  the  virus  may  be  contained 
in  the  dejecta  of  the  insect  and  be  scratched  or  rubbed  into  the  wound 
made  by  the  bite;  or  the  virus  may  be  contained  in  the  digestive  tube 
or  the  body  cavity  and  be  released  when  the  insect  bites  or  is  crushed. 

Insect-borne  infections  are  types  of  true  endemic  diseases,  as  they 
are  necessarily  limited  in  geographical  distribution  to  the  habitat  of 
the  insect  host. 

As  a  rule,  only  one  species,  or  at  most  a  single  genus,  acts  the  part 
of  a  host  for  any  particular  infection,  excepting  in  the  mechanical 
transference  of  infection  by  insects.  Malaria  is  confined  to  Anopheles, 
yellow  fever  to  Stegomyia,  Texas  fever  to  the  Margaropus  annula- 
tus,  sleeping  sickness  to  the  Glossina  palpalis,  etc.  This  is  a  question 
of  specificity.  The  specific  nature  of  some  of  these  diseases  may  be  due 
to  the  fact  that  the  parasite  is  not  pathogenic  for  other  hosts.  Thus, 
yellow  fever  and  malaria  cannot  be  given  to  any  other  animal  than 
man,  even  though  large  amounts  of  the  infected  blood  be  inoculated. 
The  disease  may  be  specific,  in  the  sense  that  it  is  confined  to  one  species, 
because  the  insect  conveying  the  infection  refuses  to  bite  other  than 
its  own  host.  True  specificity  is  found  in  all  the  cases  of  biological 
transference,  whereas  mechanical  transference  of  infection  may  take 
place  through  widely  separated  genera. 

In  some  instances  the  virus  is  transmitted  hereditarily  through  the 
insect  from  one  molt  to  another,  and  even  from  one  generation  to  the 
next.  So  far  as  known,  however,  hereditary  transmission  takes  place  only 
in  those  "insects"  having  an  incomplete  metamorphosis,  such  as  the 
ticks.  Brues  suggests  that  the  hereditary  transmission  of  a  virus  is 
practically  impossible  in  insects  passing  through  complete  metamorphosis, 
owing  to  the  active  phagocytosis  during  the  pupal  stage. 

Protozoa,  bacteria,  and  even  parasitic  worms  may  be  transferred 
by  insects.  The  character  of  the  disease  cannot  be  predicated  from  the 
nature  of  the  insect  host.  Thus,  ticks  convey  Pirosoma  and  also  spi- 
rochetes; flies  convey  trypanosomes,  bacteria,  the  eggs  of  worms,  and 
a  variety  of  other  infections;  mosquitoes  are  concerned  in  the  transmis- 
sion of  the  Plasmodium,  a  protozoon,  filaria,  a  round  worm,  and  a 
filtrable  virus  (yellow  fever). 

Insect-bjorne  diseases  may  occur  in  great  epidemics,  as  yellow  fever, 
TQalaria,   dengue,   plague,   relapsing   fever,    etc.      When    this    occurs   it 


GENERAL    CONSIDERATIONS 


203 


means  that  the  particular  insect  involved  prevails  in  enormous  num- 
bers in  the  epidemic  area. 

Ticks  and  mites  belong  to  the  lower  class  of  the  Arachnida  and 
are  not,  strictly  speaking,  insects  (insecta),  but  are  here  considered  in 
the  same  group  for  practical  convenience. 

All  the  parasitic  animals  vphich  live  upon  man  and  the  higher  ani- 
mals may  act  as  go-betweens  in  the  transportation  of  the  microorganisms 
of  disease.  Parasites  which  live  upon  the  skin  are  known  as  ectoparasites, 
in  contradistinction  to  endo parasites,  which  live  within  the  body.  The 
ectoparasites  may  be  temporary  parasites,  as  the  mosquito ;  or  permanent, 
as  the  tick,  which  spends 
all  but  its  earliest  and 
last  days  attached  to  the 
skin  of  its  host.  Between 
these  extremes  there  are 
parasites  spending  more 
or  less  of  their  life  at- 
tached to  the  host;  thus, 
the  bedbug  and  flea  are 
temporary,  whereas  lice 
are  permanent  parasites. 

Many  of  the  insect- 
borne  diseases  were  for- 
merly  known   as   "^place 

diseases."      Thus,  in  yel-    Fig.   19. — A    South    African    Blood-Sucking    Fly 

low  fever  it  was  realized 
that  the  infection  was 
not  conveyed  directly  from  man  to  man,  but  it  was  believed  that  the 
house  or  place  became  infected,  and  it  was  thought  that  the  virus 
lived  in  the  soil,  upon  the  bedding,  or  on  the  clothing.  This  led  to 
the  notion  that  fomites  or  inanimate  objects  played  an  important  role 
in  the  transference  of  disease.  The  early  studies  in  bacteriology  gave 
countenance  to  this  view  until  our  knowledge  of  the  part  played  by  in- 
sects and  the  importance  of  "contacts"  has  placed  fomites  in  a  subordi- 
nate and  oftentimes  negligible  position. 

The  prevention  of  the  class  of  infections  belonging  to  the  insect- 
borne  diseases  depends  upon  a  knowledge  and  thorough  comprehension 
of  three  factors:  (1)  the  disease,  (2)  the  parasite,  and  (3)  the  insect. 
The  suppression  or  control  of  the  insect  depends  upon  a  thorough  knowl- 
edge of  its  biology.  Entomology,  therefore,  has  become  a  vitally  im- 
portant subject  so  far  as  preventive  medicine  is  concerned.  Without 
an  acquaintance  with  the  life  history  and  habits  of  the  insect  host  there 
will  be  economic  loss,  wasted  energy,  and  disappointing  results.  The 
malaria  mosquito  is  active  at  night  and  breeds  in  the  swamps;  the 


(Pangonia),   Illustrating  Long  Proboscis  to 
Pierce  Heavy  Fur  of  Certain  Animals.  (Brues.) 


304  INSECT-BOKNE    DISEASES 

yellow  fever  mosquito  is  active  by  day  and  breeds  about  houses.  Other 
mosquitoes  have  their  own  particular  breeding  and  hiding  places.  The 
suppression  of  lice  depends  largely  upon  bodily  cleanliness,  the  suppres- 
sion of  the  bedbug  upon  house  cleanliness,  the  dangerous  fleas  come 
largely  from  association  with  other  animals,  the  flies  from  manure  and 
decomposing  organic  filth,  the  ticks  from  other  animals  and  from  the 
infested  ground  and  woods. 

For  the  control  of  the  insect-borne  diseases  it  is  not  always  neces- 
sary to  exterminate  the  particular  insect  host.  In  fact,  the  extermina- 
tion of  a  particular  species,  much  more  a  genus,  is  practically  a  biologic 
impossibility.  A  material  reduction  in  the  numbers  of  the  insects  in 
a  particular  area  will  often  result  in  an  elimination  of  the  disease. 

The  geographical  distribution  of  the  disease  is  always  more  limited 
than  the  geographic  distribution  of  the  insect  host.  Anopheles  exist 
in  many  places  where  there  is  little  or  no  malaria.  Stegomyia  mos- 
quitoes are  numerous  in  the  Philippines,  but  the  infection  has  not  yet 
been  carried  there. 

In  the  migration  of  insect-borne  diseases  it  is  usually  the  human 
host  and  not  the  insect  that  acts  as  the  traveler.  Insects,  as  a  rule, 
do  not  go  great  distances  of  their  own  volition,  and  never  over  seas 
or  from  one  country  to  another,  unless  taken  in  the  conveyances  of 
man  or  upon  some  animal  host.  When  yellow  fever  or  malaria  go 
from  one  country  to  another,  the  infection  is  translated  in  man.  The 
infected  mosquitoes  are  rarely  transported,  except  occasionally  upon 
wooden  sailing  vessels  with  water  barrels  that  afford  breeding  places. 

An  apparent  exception  to  this  statement  is  the  case  of  plague.  It  is 
the  rat  rather  than  man  that  spreads  plague  from  land  to  land.  In  this 
case,  however,  the  disease  is  primarily  an  infection  of  the  rat,  which 
carries  the  flea  along  and  man  is  secondarily  attacked.  Flies,  mosquitoes, 
and  other  insects  are  known  to  travel  or  be  blown  a  mile  or  more  upon 
the  wing. 

An  effective  campaign  against  mosquitoes,  flies,  or  other  insect 
pests  requires  the  expenditure  of  time  and  money.  Further,  it  requires 
the  assistance  of  the  entomologist,  the  engineer,  and  the  practical  ad- 
ministrator. When  the  campaign  involves  extensive  drainage  or  fllling-in 
operations,  this  calls  for  the  services  of  an  engineer  who  has  specialized 
along  these  lines.  To  attack  the  problem  without  a  complete  knowledge 
obtained  from  a  careful  study  of  the  habits  and  breeding  places  of  the 
particular  species  of  insect  will  probably  result  in  economic  waste.  Thus, 
in  New  Orleans,  during  the  yellow  fever  campaign  of  1905,  much  time 
and  effort  were  saved  by  knowledge  of  the  fact  that  the  Stegomyia  mos- 
quito did  not  breed  in  the  street  gutters  of  New  Orleans.  The  habits  and 
habitat  of  some  species  may  vary  in  different  localities,  and  a  careful 
study  of  the  local  conditions  is  important  to  insure  success.     In  the 


GENERAL    CONSIDERATIONS  205 

organization  of  a  mosquito  campaign  the  several  branches  of  the  work 
may  be  allotted  to  special  divisions,  each  consisting  of  a  foreman  and 
crew.  These  men  become  skilled  in  their  particular  duties,  and  efficiency 
is  thereby  greatly  promoted.  One  division  should  have  charge  of  the 
oiling,  another  of  the  fumigation,  another  should  seek  to  destroy  the 
natural  breeding  places,  another  should  attend  to  the  screening,  etc.  In 
fly  suppression  one  division  should  look  after  the  storing  and  handling 
of  horse  manure,  another  to  garbage  and  organic  refuse,  and  so  on.  All 
the  work  must  be  centralized  under  the  direction  of  one  person  with 
executive  ability  and  a  thorough  understanding  of  the  problem. 

The  suppression  of  insects  and  household  vermin  is  essentially  a 
question  of  cleanliness.  The  most  efi^ective  measures  are  those  which 
strike  at  the  breeding  places,  and  these  will  be  considered  in  detail  un- 
der mosquitoes,  flies,  ticks,  lice,  fleas,  and  bedbugs.  Next  to  the  sup- 
pression of  their  breeding  places,  the  most  important  measure  in  a 
household  is  to  starve  out  these  pests.  Food  must  be  so  protected 
that  insects,  mice,  and  rats  cannot  gain  access  to  it.  Floors  and  other 
surfaces  must  be  kept  clean,  so  that  they  do  not  have  the  least  fllm  of 
organic  dirt  upon  which  insects  feed.  There  should  be  no  cracks  or 
crevices  to  collect  dust  and  dirt,  which  offer  comfort  for  insect  life. 
Cleanliness  and  incessant  care  must  not  only  be  exercised  in  the  house- 
hold itself,  particularly  the  kitchen,  pantry,  dining  room,  cellar,  attic, 
and  toilets,  but  must  also  include  the  back  yard  and  surroundings  of 
the  house.  Old  cans  and  broken  bottles,  rubbish,  garbage,  and  general 
untidiness  around  the  household  afford  breeding  places,  hiding  places,  or 
food  for  vermin. 

All  the  blood-sucking  parasites  must  be  regarded  as  dangerous.  If 
they  do  not  play  the  role  of  an  intermediate  host  in  the  biological 
sense,  they  may  occasionally  transfer  infections  in  a  mechanical  way, 
or  the  little  wounds  may  allow  the  entrance  of  such  infections  as  ery- 
sipelas, the  pus  cocci,  anthrax,  tetanus,  and  other  microorganisms.  Fur- 
ther, all  blood-sucking  parasites  are  potentially  dangerous,  in  that  new 
diseases  may  be  established  as  the  old  ones  must  have  been  established 
at  one  time  through  the  triple  alliance  of  host,  insect,  and  parasite. 

Science  has  demonstrated  the  danger  from  insects.  Experience  long 
ago  decided  that  a  healthy  home  must  be  free  of  insects  and  vermin  of 
all  kinds — it  remains  for  the  future  to  extend  this  kind  of  cleanliness 
to  municipal  housekeeping  and  rural  sanitation. 

The  principal  insect-borne  diseases,  their  causes,  and  the  insect  re- 
sponsible in  each  case  are  stated  in  the  following  table : 


206 


INSECT-BOENE    DISEASES 
The  Principal  Insect-borne  Diseases. 


MOSQUITOES 


Malaria     (Laveran,     1880,     the 
parasite;    Ronald    Ross,    1895- 
1898,  relation  to  the  mosquito) 

Plasmodium  malariae  (Laveran) 
Plasmodium   vivax    (Grassi   and 

Feletti) 
Plasmodium  falciparum  (Welch) 

Anophelinae 

Yellow    Feveh    (Reed,    Carroll, 
Lazear,  and  Agramonte,   1900- 
1902) 

A  filtrable  virus 

Stegomyia  calopus  (Aedes  calopus) 

FiLARiASis     (Demarquay,     1863; 
Manson,  1899) 

Filaria  bancrofti 

Culex  fatigans  and  others 

Dengue  (Graham,  1903;  Ashburn 
and  Cleaia,  1907) 

A  filtrable  virus 

Culex  fatigans 

FLxj 


Sleeping     Sickness     (Gambian) 
(Button,  1902) 


Trypanosom,a  gambiense 


A  tsetse  fly — Qlossina  palpalis 


Sleeping    Sickness    (Rhodesian) 
(Stephens  &  Fantham,  1910) 


Trypanosomxi  rhodesiense 


A  tsetse  fly — Glossina  morsitans 


Nagana   (of  cattle,   etc.)    (Bruce, 
1896) 


Trypanosom-a  brucei 


A  tsetse  fly — Glossina  morsitans 


SuHRA     (of    horses,    etc.)     (Steel, 
1885) 


Trypanosoma  evansi 


Tahaninae,     Stomoxys     calcitrans, 
and  other  biting  flies;  also  fleas 


Pappataci    Fever    (3   day   fever) 
(Doerr,  1909) 


A  filtrable  virus 


Phlebotomus  pappatasii — A  dipter- 
ous biting  gnat 


Calabar     Swelling     (Loa    loa) 
(Cobbold,  1864;  Manson,  1891) 


Filaria  diurna 


Chrysops  dimidiatus — A  biting  fly 


Poliomyelitis  (?)  (Rosenau  and 
Brues,  1912)  (Flexner  and 
Noguchi,  1913) 


A  filtrable  virus 


Stomoxys  calcitrans — The  stable  fly 


South  American  Trypanoso- 
miasis (Barbiero  fever)  (Chagas, 
1909) 


Trypanosoma  cruzi 


Lamus    megislus — A    hemipterous 
biting  insect 


Typhoid,  Cholera,  Dysentery, 
etc.  Contagious  ophthalmia, 
"pink  eye,"  erysipelas,  anthrax, 
glanders,  skin  infections.  Small- 
pox and  other  exanthemata. 


Flies  and  other  insects,  by  mechan- 
ical transmission. 


TICKS 

Texas  Fever  (of  cattle)    (Smith 
&  Kilborne,  1893) 

Babesia  bigemina 

Magaropus  annulatus 

Rocky  Mountain  Spotted  Fever 
(Ricketts,  1906;  Wolbach,  1916) 

A  bacillus  (?) 

Dermacentor  andersoni 

Canine     Babesiasis     (Plana     & 
Valeric,  1895) 

Babesia  canis 

Haemaphysalis  leachi 

La  Spihillose  des  Poules  (Mar- 
choux  &  Salembeni,  1903) 

Spiroschaudinnia  marchouxi 

Argas  persicus  and  others 

Relapsing   Fever    (W.    Africa) 
(African  tick  fever)  (Button  and 
Todd,  1904) 

Spiroschaudinnia  duttoni 

Ornithodorus  moubata 

BEDBUGS 

European      Relapsing      Fever 
(Obermeier,  1873) 

Spiroschaudinnia  recurrentis 

Clinocoris  lectularis  (?) 
Pediculi  (?) 

Indian  Kala-azab  (Ross,  1903) 

Leishmania  donovani 

Clinocoris  rotundatus 
Conorhinus  (?) 

(Continued  next  page.) 


GEN^EEAL    CONSIDEEATIONS 
Insect-borne  Diseases —  ( Continued) 


207 


DISEASE 

CAUSE 

INSECT 

LICE 

Algerian  Relapsing  Fever  (Ser- 
gent  and  Foley,  1910) 

Spiroschaudinnia  berbera 

Pediculi 

European      Relapsing      Fever 
(Obermeier,  1873) 

Spiroschaudinnia  recurrentis 

Clinocoris  (?) 
Pediculi  (?) 

Asiatic  Relapsing  Fever   (Car- 
ter, 1877) 

Spiroschaudinnia  carteri 

Pediculus  vestimentis  (?) 

Ttphus     Fever     (Nicolle,     1909; 
Ricketts  &  Wilder,  1910;  Ander- 
son &  Goldberger,  1910) 

B.    typhus    exanthematicus     (?) 
(Plotz,  1914) 

Pediculus  vestimenti 
Pediculus  capitis 

FLEAS 

Plague   (Kitasato,    1894;  Yersin, 
1894) 

B.  pestis 

Xenopsylla  cheopis  and  others 

Infantile    Kala-azar    (Pianese, 
1905) 

Leishmania  infantum 

Ctenocephalus  canis  (?) 

The  following  table  gives  a  list  of  the  principal  diseases  which  are 
transmitted  by  "intermediate"  hosts  other  than  insects. 


DISEASE  AND  ADULT 
PARASITE 

INTERMEDIATE  OR 
USUAL  HOST 

INFECTING  STAGE 
OF  PARASITE 

MODE  OF 
INFECTON 

Liver  fluke 
Fasciola  hepatica 

Snails 
Limnaeus 

Cercariae 

Ingestion 

Liver  fluke 
Clonorchis  endemicus 

Fish 

Encysted  stage 

Ingestion 

Lung  fluke 
Paragonimus  westermanii 

Fresh-water  crab 
Potamon  dehaanii 

Encysted  larvae 

Ingestion 

"Katayama  disease" 
Schistosomum  japonicum 

Fresh-water  snails 
Katayama  nosophora 

Cercariae 

Through 
the  skin 

Fish  tapeworm 
Dibothricephalus  latus 

Pike,  salmon,  etc. 

Plerocercoids 

Ingestion 

Dog  tapeworm 
Dypilidium  caninum 

Dog  fleas  and  dog  lice 

Cysticercoids 

Contact 
with  dogs 

Rat  tapeworm 
Hymenolepis  diminuta 

Meal  moth,  Asopia  farinalis 
and  other  insects 

Cysticercus 

Ingestion 

Dwarf  tapeworm 
Hymenolepis  nana 

(?) 

Cysticercoid 

Ingestion 

Pork  tapeworm 
Taenia  solium 

Swine 

Cysticercus 

Ingestion 

Beef  tapeworm 
Taenia  saginata 

Cattle 

Cysticercus 

Ingestion 

Hydatid  disease 
Echinococcus  granulosus 

Dogs 

Onchosphere 

Ingestion 

Guinea  worm 
Dracunculus  medinensis 

A  small  crustacean 
Cyclops  coronatus 

Larvae 

Ingestion 

Lamhlia  intestinalis 

Rats,  mice 

Encysted  stage 

Ingestion 

Trichiions 
Trichinella  spiralis 

Swine 

Encysted  stage 

Ingestion 

A  number  of  other  diseases  are  suspected. 


208  INSECT-BOENE    DISEASES 


INSECTICIDES 

Practically  all  the  germicidal  agents  are  also  insecticides.  There 
are  some  exceptions  to  this  statement,  notably  formaldehyd,  which  is  a 
potent  germicide,  but  has  little  or  no  effect  upon  insect  life  in  its  gaseous 
state. 

The  action  of  insecticides  may  be  considered  under  three  classes: 
(1)  those  that  act  as  general  protoplasmic  poisons,  such  as  strong  acids 
or  alkalies,  hydrocyanic  acid,  sulphur  dioxid,  etc.;  (2)  those  that  suf- 
focate the  insects,  such  as  oily  substances,  and  (3)  those  that  act  upon 
the  nervous  structures,  such  as  chloroform,  ether,  and  other  general 
anesthetics. 

Another  classification  considers  insecticides  under  four  groups:  (1) 
those  used  by  contact  in  liquid  form  or  in  solution;  (2)  those  used 
by  contact  in  dry  or  powdered  form;  (3)  those  used  by  contact  in 
vapor  form;  (4)  those  used  by  mixing  with  food  and  which  are  poisonous 
when  ingested.  Insects  differ  markedly  in  their  power  of  resisting 
insecticides.  Those  with  well-developed  chitinous  protection,  such  as 
bedbugs  and  roaches,  are  more  difficult  to  kill  than  flies,  fleas,  and 
mosquitoes. 

The  most  practical  of  the  insecticides  for  the  destruction  of  the 
winged  insects  in  an  enclosed  space  are  those  that  may  be  used  in  the 
gaseous  state.  Of  these,  sulphur  dioxid,  hydrocyanic  acid  gas,  carbon 
bisulphid,  or  carbon  tetrachlorid  are  most  commonly  employed  and  are 
most  reliable.  The  uses  and  limitations  of  these  and  other  insecticidal 
agents  will  now  be  considered  in  detail. 

Preparation  of  the  Room  for  Fumigation. — It  is  more  important  to 
tightly  seal  a  room  in  which  insects  are  to  be  destroyed  than  where 
only  a  germicidal  action  of  the  gas  is  looked  for.  Insects  may  escape 
through  minute  openings,  and  they  may  hide  in  nooks  and  corners 
where  the  gas  permeates  slowly  and  feebly,  or  may  take  cover  under 
the  folds  of  crumpled  paper  or  folded  fabrics,  and  thus  escape  the  in- 
secticidal action  of  the  gas.  Self-preservation  tempts  mosquitoes  and 
other  insects  as  well  as  rats  and  mice  to  seek  the  light  when  in  the 
presence  of  an  irritating  gas.  It  is,  therefore,  convenient  to  darken 
the  place  to  be  treated,  leaving  one  source  of  light.  The  dead  vermin 
may  then  be  readily  collected  about  this  place. 

Strips  of  paper  should  be  pasted  over  doors  and  windows.  Cracks 
and  crevices  may  be  caulked  with  towels,  waste,  or  other  suitable  sub- 
stance. Ventilators,  fireplaces,  hot-air  registers,  and  all  openings  into 
the  room  must  be  covered,  otherwise  both  the  gas  and  the  insects  will 
escape.  Closets  and  small  doors  should  be  opened  and  all  the  drawers, 
lockers,  and  similar  places  exposed  in  such  a  way  that  the  gas  raav 


mSECTICIDES 


209 


have  fresh  access  to  remote  corners.  Furniture  should  be  moved  away 
from  the  walls.  Fabrics,  paintings,  instruments,  bright  metal  work,  or 
other  objects  liable  to  injury  may  be  removed  or  covered,  especially  when 
sulphur  is  used. 


Fig.  20. — Example   of    Sealing    Do»iks    lam    PukP' 


OF   Fumigation. 


The  Relative  EiRciency  of  Insecticides. — McClintock,  Hamilton,  and 
Lowe  ^  have  tested  a  number  of  insecticidal  substances,  the  values  of 
which  are  shown  in  Table  4,  Avhich  gives  a  list  of  the  substances  tested 
and  the  species  of  insects  used  in  the  experiments,  together  with  the 
quantity  of  each  substance  which,  when  properly  transformed  into 
vapors,  was  sufficient  to  kill  the  species  indicated.  The  coefficient  col- 
umn shows  the  inverse  ratio  between  this  quantity  and  8  grams,  the 
weight  of  sulphur  which,  when  burned,  kills  the  bedbug  in  the  800,000 
c.  c.  of  inclosed  space. 

The  efficient  dilution  of  the  vapors  of  any  substances  may  be  ob- 
tained from  this  coefficient  by  multiplying  by  100,000. 

For  example,  if  'one  wishes  to  use  carbon  disulphid,  by  consulting 
No.  28  in  the  table  it  is  shown  that  24  grams  were  required  to  kill 

^Jour.  Am,  Pub,  Health  Assn.,  Vol.  II,  No.  4,  Apr.,  1911,  p.  227. 


310 


INSECT-BOENE    DISEASES 


bedbugs,  while  only  8  grams  were  required  of  sulphur.  It  is  therefore 
ouly  one-third  as  strong  and  its  coefficient  is  0.3-1- .  Its  efficient  dilu- 
tion is  33,000. 

TABLE  4 

INSECTICIDES 
Time  of  exposure — Varied  as  conditions  required. 
Column  1 — Quantity  used  to  kill  the  specified  insect. 
Column  2 — Coefficient  of  efficiency  compared  with  the  efficiency  of  sulphur  dioxid  on  bedbugs. 


Substance 


Bedbug 


Cockroach 


Housefly 


Clothes 
Moth 


Mosquito 


1  Sulphur  Dioxid]as  Sulphur .  . . 

2  Pyridin 

3  Pyridin  Bases  (Merck) 

4  Quinolin 

5  Creosote  Oil .  . 

6  Carbolic  Acid 

7  Naphthalene 

8  Kerosene 

9  AniUn  Oil 

10  Cedar  Oil 

11  Citronella  Oil 

12  Cloves  Oil ... 

13  Peppermint  Oil 

14  Pennyroyal  Oil 

15  Australene 

16  Turpentine  (Oregon  Fir) 

17  Oil  Pinus  Palustris 

18  Oil  Turpentine 

19  Turpentine  (Mich.  Wood) .  .  .  . 

20  Benzaldehyd 

21  Nitrobenzol 

22  Ammonia  28% 

23  Alcohol,  Ethyl 

24  Alcohol,  Methyl 

25  Acetone 

26  Chloroform 

27  Ether  (Ethyl  Oxide) 

28  Carbon  Disulphid 

29  Carbon  Tetrachlorid 

30  Chloretone 

31  Camphor 

32*Niootin,  80%  Sol 

33  Hydrocyanic   Acid,    as   Potas- 

sium Cyanid 

34  Paraf orm 

35tFormaldehyd  40%  Sol 

36  Stramonium  Leaves 

37  Sabadilla  Seeds 

38  Chrysanthemum  Flowers 


4  + 

8 

8  + 
16  + 

6.3  + 
11.5  + 

4  + 

4  + 

4  + 

8  + 

8  + 
36  + 
16  + 
20  + 
16  + 

4  + 

8  + 
36  + 
80  + 
80  + 
40  + 
40  + 


1 

1 

1.6 

1 

2 

1 

1 

0.5 

1.3 

0.7 

2 

2 

2 

1 

1 

0.2 

0.5 

0.4 

0.5 

2 

1 

0.2 

0.1 

0.1 

0.2 

0.2 


4 
4 
4 
8 
4  + 


16  + 
6.3  + 
11.5 

4  + 

4  + 

4  + 

8  + 

8  + 
36  + 
16  + 
20  + 
24  + 

4  + 

8 
36  + 
80  + 
80  + 
40  + 
40  + 


2 

2 

2 

1 

2 

1 

1 

0.5 

1.3 

0.7 

2 

2 

2 

1 

1 

0.2 

0.5 

0.4 

0.3 

2 

1 

0.2 

0.1 

0.1 

0.2 

0.2 


3.2 

2 

1.6 


2.5 

4 

5 


2.6 


24 
40 

4  + 
8  + 
25 

6.3 

8  + 
54  + 
10 

+ 
80  + 


0.3 
0.2 
2 
1 

4 

1.3 
1 

0.1 
0.8 


0.1 


36 

40  + 
4  + 
8 

25 

6.3 

8  + 
54  + 
10 

+ 
+ 


0.2 
0.2 
2 
1 

4 

1.3 
1 

0.1 
0.8 


0.1 


2 

4  + 

6.3 

8 

2 

2 

4 

4 

3.2 
36  + 

4 
20 
16 

2 

1.6 
20  + 
80  + 
80  + 
40  + 
16  + 

15  + 
4 

40  + 
4 
4 
6 

2 
4 

16  + 
10  + 
16 

2.6 


4 
1 
4 
2 

1.3 
1 
4 
4 
2 
2 

2.5 
0.2 
2 

0.4 
0.5 
4 
5 

0.4 
0.1 
0.1 
0.2 
0.5 
0.5 
2 

0.2 
2 
2 
20 

4 

2 

0.5 

0.8 

0.5 

3 


4 

4 

6.3 

2 

4 

2 

4  + 

4 

8 
16  + 

4 
20 
16 

2 

1.6 
36  + 
80  + 
80  + 
40  + 
16  + 


3 

5 

5 

4 

8 

1 

2 

2 

1.3 

4 

2 

4 

2 

2 

1 

0.5 

2 

0.4 

0.5 

4 

5 

0.2 

0.1 

0.1 

0.2 

0.5 


3.2 
1.6 


2.5 

5 


4 
1 

4  + 
4 
1 
1 
1 
2 
1 
2 
8 
2 
10 


4 
1 
4 
0.8 


1 

1 
20 
80 
80  + 
14  + 
16  + 


0.4 
0.1 
0.1 
0.2 
0.5 


2 

40  + 

4 

4 
25 

1 

8 

16  + 
10  + 
16  + 

4 


4 

0.2 
2 
2 
40 


1 

0.5 

0.8 

0.5 

2 


20 
0.2 


4 
100 


The   +  sign  after  a  number  indicates  that  this  quantity  was  the  largest  used  and  that  it  was 

insufficient. 
*  Coefficient  of  nicotin  based  on  100%  alkaloid, 
t  Quantity  of  formaldehyd  to  be  an  efficient  germicide  is  13J^  c.  c.  or  a  coefficient  of  0.625. 


The  best  methods  of  generating  gases  for  fumigating  purposes  are 
considered  below.  For  further  information  concerning  these  substances, 
with  special  reference  to  their  germicidal  action,  see  Section  XII. 

To  insure  success  the  gas  used  to  fumigate  a  room  should  be  liber- 
ated in  a  large  volume  in  a  short  time.  If  the  gas  is  evolved  slowly 
much  of  it  will  be  lost  before  the  room  can  become  charged  with  a 
sufficient  amount  to  kill  the  insects- 


INSECTICIDES  311 

The  anioiiiit  of  gas  and  the  time  of  exposure  stated  in  each  case 
are  the  minimum.  When  large,  leaky,  or  irregularly  shaped  spaces  are 
to  be  fumigated,  the  amount  of  gas  should  be  increased  and  the  time 
of  exposure  prolonged.  It  is  also  advisable  to  generate  the  fumes 
in  as  many  different  places  as  practicable,  as  this  favors  rapid  diffu- 
sion. 

Sulphur,. — Sulphur  is  one  of  the  most  valuable  insecticides  we  pos- 
sess. It  may  be  used  either  as  a  gas — ^SOg — or  in  its  povi^dered  form — 
flowers  of  sulphur. 

Sulphur  dioxid  is  destructive  to  all  forms  of  life.  It  will  kill 
mosquitoes,  flies,  fleas,  roaches,  bedbugs,  and  all  kinds  of  vermin,  in- 
cluding rats  and  mice.  While  sulphur  dioxid  is  one  of  the  most  de- 
pendable insecticides  it  is  a  rather  feeble  germicide.  It  is  limited 
in  practice  on  account  of  its  destructive  and  corrosive  action.  This 
destructive  action  results  from  the  sulphurous  acid  and  sulphuric  acid 
produced  in  the  presence  of  moisture.  Fortunately  the  dry  gas  is  quite 
as  poisonous  to  mosquitoes,  flies,  rats,  mice,  etc.,  as  the  moist  gas. 
Dry  sulphur  dioxid,  however,  has  absolutely  no  germicidal  value.  Dry 
sulphur  dioxid  does  not  tarnish  metals,  does  not  rot  fabrics,  and  does 
not  bleach  pigments.  Fumigation  with  SO2  may,  therefore,  be  done 
with  little  damage  to  property  on  dry  days.  Metal  work,  fabrics,  and 
pigments  that  cannot  be  removed  from  the  room  may  be  protected  from 
the  sulphur  fumes  by  simple  mechanical  devices. 

Sulphur  dioxid  may  be  produced  either  by  burning  sulphur  or  by 
liberating  liquefied  sulphur  dioxid.  The  methods  of  generating  the 
gas  will  be  found  on  page  1139.  Two  pounds  of  sulphur  burned  for  each 
thousand  cubic  feet  of  air  space  and  an  exposure  of  two  hours  is  sufficient 
to  kill  mosquitoes,  flies,  and  other  insects  in  a  small  tight  space.  Three 
to  four  hours  are  ample  for  rats  and  mice.  If  the  space  is  large  or  leaky 
the  amount  of  gas  should  be  increased  and  the  time  of  exposure  pro- 
longed. Sulphur  dioxid  has  surprising  power  of  penetration  through 
clothing  and  fabrics.  In  very  dilute  proportions  it  will  in  one  hour's 
time  kill  mosquitoes  even  when  covered  with  eight  layers  of  toweling.  It 
has  absolutely  no  power  of  penetration  when  used  as  a  germicide.  This 
substance,  which  has  so  long  been  disparaged  as  a  disinfectant  because  it 
fails  to  kill  spores  and  many  spore-free  bacteria  under  certain  condi- 
tions, must  now  be  considered  as  holding  first  rank  as  an  insecticide. 
For  consideration  of  sulphur  dioxid  as  a  germicide  see  page  1138. 

Flowers  of  Sulphur. — Sulphur  in  its  dry,  powdered  state  is  use- 
ful against  a  number  of  parasites.  In  this  form,  however,  it  has  little 
use  as  an  insecticide  in  preventive  medicine,  not  being  efficacious  against 
bedbugs,  ants,  roaches,  or  fleas. 

It  may  be  applied  in  several  ways,  the  simplest  of  which  is  to 
sprinkle  the   dry   sulphur   about  the   places   where  insects   are   found. 


212  INSECT-BOENE    DISEASES 

Flowers  of  sulphur  may  also  be  combined  advantageously  with  other 
insecticides,  such  as  kerosene  emulsion,  resin  wash,  or  soap  wash.  It 
should  first  be  mixed  into  a  paste  and  then' added  to  the  spray  tank 
in  the  proportion  of  about  1  or  2  pounds  to  50  gallons.  It  is  particu- 
larly efficacious  for  the  destruction  of  the  mites  and  rust  of  plants  and 
fruits. 

Sulphur  in  the  form  of  an  ointment  is  particularly  obnoxious  to 
ticks  and  other  ectoparasites.  The  itch-mite  {Sarcoptes  scahiei)  is 
very  susceptible  to  the  flowers  of  sulphur,  which  is,  therefore,  one  of 
the  ingredients  of  almost  all  ointments  used  in  this  skin  affection. 

Sulphur  dips  are  used  to  destroy  the  mites  on  domestic  animals. 
The  formula  now  recommended  for  the  treatment  of  scabies  of  cattle  is 
as  follows :  Flowers  of  sulphur,  24  pounds ;  unslaked  lime,  12  pounds ; 
water,  100  gallons.  It  is  common  experience  that,  while  sulphur  dips  may 
be  depended  upon  to  destroy  the  mites,  they  do  not  destroy  the  eggs, 
hence  the  treatment  should  be  repeated  in  about  10  days,  which  per- 
mits time  for  the  eggs  to  hatch  and  develop  into  adults.  The  lime  and 
sulphur  dips  are  widely  used  for  both  cattle  and  sheep  affected  with 
scabies.  The  advantages  of  this  class  of  dips  over  arsenical  dips  are  that 
they  are  effective,  but  not  poisonous  for  cattle  or  man.  For  the  Texas 
fever  tick  lime  and  sulphur  dips  are  not  effective  and  arsenic  should 
therefore  be  used. 

Formaldehyd. — Formaldehyd,  while  holding  the  front  rank  as  a 
germicide,  is  a  feeble  insecticide.  The  gas  seems  to  have  no  effect 
whatever  upon  roaches,  bedbugs,  and  insects  of  this  class  even  after 
prolonged  exposure  to  very  high  percentages.  As  a  differential  poison 
formaldehyd  gas  is  a  very  remarkable  substance.  It  destroys  bacteria 
almost  instantly,  but,  while  it  is  irritating  to  the  higher  forms  of  ani- 
mal life,  it  is  not  very  toxic.  I  have  repeatedly  found  that  roaches  and 
other  insects  with  strong  chitinous  protection  seem  unharmed  after 
12  hours'  exposure  to  very  strong  percentages  of  the  gas  in  air-tight  dis- 
infecting chambers.  Mosquitoes  may  live  in  a  weak  atmosphere  of  the 
gas  over  night.  It  will  kill  them,  however,  if  the  gas  is  brought  in  direct 
contact  with  them  in  the  strength  and  time  prescribed  for  bacterial 
disinfection. 

When  a  weak  insecticidal  gas  is  used  it  is  much  more  difficult  to 
obtain  direct  contact  between  the  gas  and  the  insects  than  between 
the  gas  and  germs,  because  the  sense  of  self-preservation  aids  the  for- 
mer in  escaping  from  the  effects  of  the  irritating  substance.  Mos- 
quitoes and  other  insects  hide  in  the  folds  of  towels,  bed  clothing, 
hangings,  fabrics,  and  out-of-the-way  places  where  the  formaldehyd  gas 
does  not  permeate  in  sufficient  strength  to  kill  them.  The  gas  is 
polymerized  and  deposited  as  paraform  on  the  surface  of  fabrics  which 
prevent  its  penetration,  and  large  quantities  are  lost  by  being  absorbed 


INSECTICIDES  213 

by  the  organic  matter  of  woolen  fabrics.  Mosquitoes  have  a  lively  in- 
stinct in  finding  cracks  or  chinks  where  fresh  air  may  enter  a  room 
or  other  places  where  the  gas  is  so  diluted  that  they  escape  destruc- 
tion. Therefore,  formaldehyd  gas,  as  well  as  other  culcides,  cannot 
be  trusted  to  kill  all  the  mosquitoes  in  a  room  which  cannot  be  tightly 
sealed.  On  account  of  its  feeble  action,  formaldehyd  is  not  recom- 
mended as  reliable. 

For  the  best  methods  of  evolving  formaldehyd  gas,  the  quantities 
to  be  used,  and  other  details  of  the  process,  see  page  1133. 

Formaldehyd  gas  in  watery  solution,  known  as  formalin,  is  use- 
ful for  the  destruction  of  flies.  Small  quantities  of  dilute  formalin  (4 
per  cent.)  placed  in  saucers  about  the  room  attract  flies.  They  drink 
the  fluid,  which  soon  kills  them. 

Pyrethmm. — Pyrethrum  is  a  popular  and  much  used  insecticida 
because  it  is  comparatively  cheap  and  non-poisonous  to  man  and  the 
higher  animals.  It  is  also  non-corrosive,  but  unfortunately  it  is  not 
very  powerful  for  the  destruction  of  roaches,  ants,  bedbugs,  flies,  fleas, 
mosquitoes,  etc.     It  has  no  germicidal  action. 

Pyrethrum,  also  sold  under  the  names  of  Buhach  or  Persian  insect 
powder,  or  simply  "insect  powder,"  is  the  flowers  of  the  Chrysanthemum 
roseum  and  the  Chrysanthemum  carneum,  both  hardy  perennials  and 
resembling  camomile  in  appearance.  According  to  Kalbrunner,  4  grains 
of  the  pure  powder  sprinkled  on  a  fly  in  a  vial  should  stupefy  it  in 
one  minute,  and  kill  it  in  2  or  3  minutes.  It  acts  on  insects  exter- 
nally through  their  breathing  pores.  When  brought  in  direct  con- 
tact with  them  it  is  fatal,  to  many  forms  of  biting  and  sucking  in- 
sects, such  as  roaches,  flies,  and  ants.  It  may  be  used  either  as  a  dry 
powder  or  by  its  burning  fumes.  As  a  dry  powder  it  may  be  used 
pure  or  mixed  with  flour,  in  which  form  it  should  be  puffed  about  the 
room,  especially  into  cracks. 

When  pyrethrum  powder  is  ignited  it  smolders,  giving  off  fumes 
which  stun,  but  do  not  always  kill,  mosquitoes.^  It  is  not,  therefore, 
a  dependable  insecticide.  This  uncertainty  and  the  price  of  pyrethrum 
restrict  its  field  of  usefulness. 

Pyrethrum  fumes  do  not  corrode  metals  or  act  injuriously  upon 
fabrics  and  pigments.  However,  a  slight  brown  deposit  is  occasionally 
left  on  exposed  surfaces- which  may  stain  linen  a  yellowish  color.  This 
deposit  or  stain  is  readily  washed  out,  or  soon  fades. 

Pyrethrum  powder  has  been  used  very  much  in  those  cases  where 
sulphur  is  prohibited  on  account  of  the  danger  of  damage  to  paintings, 
fabrics,  tapestries,  metal  work,  musical  instruments,  upholstered  furni- 
ture, and  the  like.     It  is  used  in  the  proportion  of  2  pounds  per  1,000 

'  Tobacco  smoke  and  other  substances  which  produce  dense  fumes,  particu- 
larly those  containing  pyroligneous  products,  will  kill  mosquitoes. 


314  INSECT-BOENE    DISEASES 

cubic  feet  of  air  space,  the  exposure  being  for  not  less  than  4  hours. 
As  its  insecticidal  effect  is  uncertain,  it  is  necessary  carefully  to  sweep 
up  and  burn  all  the  mosquitoes  that  have  been  stunned  and  are  appar- 
ently dead  after  the  fumigation.  Most  of  these  mosquitoes  will  be  found 
on  the  window  sill  or  on  the  floor  close  to  the  window,  where  they  are  at- 
tracted by  the  light  in  their  efforts  to  find  an  exit  to  escape  the  fumes. 
Advantage  should  be  taken  of  this  tendency  of  the  mosquito  to  seek  the 
light  by  darkening  all  but  one  window. 

Sheets  of  paper  containing  some  sticky  preparation  may  be  placed 
upon  the  floor  and  upon  the  window  sill  in  order  to  catch  the  mos- 
quitoes. A  satisfactory  adhesive  preparation  may  be  made  by  dissolv- 
ing, by  the  aid  of  heat,  65  parts  of  colophony  resin  in  35  parts  of 
castor  oil.     This  simplifies  the  collection  and  disposal  of  the  insects. 

Pyrethrum  powder  should  be  distributed  in  pots  or  pans  and  set  on 
fire  with  a  little  alcohol,  which  should  first  be  sprinkled  over  it.  The 
quantity  apportioned  to  any  one  pot  or  pan  should  not  exceed  II/2 
inches  in  depth,  if  the  exposure  is  to  be  for  4  hours.  The  pots  and 
pans  should  be  set  on  bricks  to  prevent  scorching  the  floor. 

Much  of  the  pyrethrum  upon  the  market  is  impure,  which  further 
weakens  what  is  a  feeble  insecticide  at  best. 

Phenol-camphor  {Mim's  Culicide). — Camphophenique  or  phenol- 
camphor  is  prepared  by  rubbing  up  equal  weights  of  phenol  crystals  and 
camphor.  It  may  be  more  conveniently  prepared  by  first  liquefying  the 
phenol  by  gentle  heat  and  then  pouring  it  over  the  camphor.  The  cam- 
phor and  phenol  combine  to  form  a  new  chemical  compound,  which  re- 
mains fluid  at  ordinary  temperatures.  This  preparation  was  first  used 
on  a  considerable  scale  during  the  yellow  fever  epidemic  in  New  Or- 
leans toward  the  close  of  1905  at  the  suggestion  of  Mr.  Mim,  the  city 
chemist.  At  this  time  I  took  the  opportunity  of  making  a  number  of 
tests  with  Dr.  Metz  concerning  the  culicidal  value  of  this  substance. 
The  effect  of  the  fumes  on  mosquitoes  was  later  studied  by  Berry  and 
Francis.  When  phenol-camphor  is  moderately  heated  it  gives  off  dense 
fumes,  which  rise  rapidly  and  diffuse  slowly,  and  after  30  to  60  min- 
utes, depending  upon  the  amount  employed  and  the  temperature  of  the 
air,  the  fumes  condense  and  are  deposited  as  a  slight  moisture  on  all 
exposed  surfaces.  As  a  culicide  phenol-camphor  may  be  compared  to 
pyrethrum;  the  fumes  stun  the  mosquitoes,  but  do  not  invariably  kill 
them.  The  fumes  are  somewhat  irritating  to  the  mucous  membranes, 
especially  the  eyes;  they  may  cause  dizziness,  headache,  cloudy  urine, 
and  other  mild  symptoms  of  phenol  poisoning  in  susceptible  individuals 
much  exposed  to  their  inhalation.  The  fumes  of  phenol-camphor  do 
not  tarnish  metals,  rot  fabrics,  or  bleach  pigments.  They,  however, 
have  the  disagreeable  property  of  softening  the  varnish  of  surfaces  on 
which  they  condense.     On  account  of  its  slight  power  of  diffusion,  rela- 


mSECTICIDES  315 

tively  high  cost,  and  uncertainty  of  action,  it  cannot  take  the  place  of 
sulphur  except  in  the  parlor,  pilot  house,  and  other  compartments  where 
sulphur  is  prohibited  on  account  of  the  damage  it  produces.  Compared 
with  pyrethrum,  phenol-camphor  is  less  expensive,  more  certain,  and 
not  so  objectionable  to  the  housekeeper.  Its  use  involves  a  little  more 
care  and  intelligence  than  that  required  for  the  simple  burning  of  py- 
rethrum. If  it  is  overheated  it  will  take  fire,  and  no  culicidal  action 
is  produced.  Goldberger  concludes  that,  for  use  on  a  large  scale,  as 
in  times  of  epidemics,  in  the  hands  of  trained  fumigators,  phenol-cam- 
phor is,  on  the  whole,  to  be  preferred  to  pyrethrum,  being  more  easily 
transportable  on  account  of  the  small  bulk  required,  and  because  the 
fumes  condense  quickly  and  the  room  may,  if  desired,  be  entered  in  an 
hour  and  the  apparatus  removed,  thus  making  it  possible  to  fumigate 
a  larger  number  of  rooms  in  a  given  time  with  less  labor  than  in  the 
case  of  either  sulphur  or  pyrethrum. 

Phenol-camphor  is  used  in  the  proportion  of  4  ounces  to  every  thou- 
sand cubic  feet  of  air  space,  and  with  an  exposure  of  2  hours.  In  this 
proportion  and  time  the  film  of  condensation  is  slight  and  is  rapidly  dis- 
sipated after  the  doors  and  windows  are  opened.  The  preparation  of 
the  room  is  the  same  as  that  described  above.  The  phenol-camphor  ap- 
portioned to  the  room  to  be  fumigated  should  be  distributed  in  agate- 
ware basins,  not  more  than  8  to  10  ounces  to  any  one  basin.  Each 
basin  is  set  over  an  alcohol  lamp  at  such  an  elevation  and  in  such  a 
manner  as  will  permit  a  rapid  evolution  of  the  fumes.  Care  must  be 
taken  not  to  heat  the  basin  so  quickly  as  to  cause  the  liquid  to  become 
overheated  and  take  fire.  This  point  must  first  be  determined  experi- 
mentally for  each  type  of  lamp  used.  One  of  the  small  brass  alcohol 
vapor  lamps  to  be  found  on  the  market  serves  excellently.  As  a  saie- 
guard  against  accidents  the  lamp  should  stand  in  a  pan  containing  about 
one-half  inch  of  water.  The  basin  containing  the  phenol-camphor  may 
be  set  upon  a  section  of  galvanized  iron  stove-pipe,  at  one  end  of  which 
sectors  are  cut  out  so  as  to  form  legs  of  a  length  equal  to  the  height  of 
the  lamp;  just  below  the  upper  margin  of  the  pipe  a  series  of  holes 
are  punched  so  as  to  provide  for  draft.  The  stove-pipe  should  be  of 
such  a  length  as  to  support  the  basin  containing  the  phenol-camphor 
about  10  inches  above  the  flame.  This  ingenious  and  simple  device, 
suggested  by  Berry  and  Francis,  acts  as  a  chimney,  protects  the  flame, 
is  relatively  cheap,  and  has  proven  satisfactory. 

Hydrocyajiic  Acid  Gas. — Hydrocyanic  acid  gas  is  extremely  poison- 
ous to  all  forms  of  life.  It  kills  roaches,  bedbugs,  mosquitoes,  fleas, 
flies,  rats,  mice,  and  other  vermin  with  great  certainty  and  very  quickly. 
It  is  much  less  poisonous  to  the  higher  forms  of  plant  life,  although 
it  has  a  certain  amount  of  germicidal  power.  Hydrocyanic  acid  gas 
is  much   used  in  greenhouses  for  the  destruction  of  insect  pests  and 


216  INSECT-BORNE    DISEASES 

for  scale  and  other  parasites  of  fruit  trees.  The  gas  has  a  distinct 
place  in  the  fumigation  of  granaries,  stables,  ships,  barns,  outhouses, 
railroad  cars,  and  other  uninhabited  structures  infested  with  vermin. 
It  is  also  extensively  used  in  flouring  mills  against  weevils,  in  rail- 
road cars  against  bedbugs,  and  in  tobacco  warehouses  against  insects  in 
general.  It  should  be  used  in  the  household  only  with  the  greatest 
precaution,  as  the  least  carelessness  with  it  would  probably  mean  the 
loss  of  human  life.  It  has  the  marked  advantage  that  it  does  not  harm 
metals,  fabrics,  or  pigments,  and  may  be  used  in  the  most  expensive 
drawing  rooms. 

Hydrocyanic  acid  gas  is  lighter  than  air  and  has  an  agreeable 
aromatic  odor  quite  familiar  in  the  flavoring  essence  of  bitter  almonds. 
The  best  method  of  generating  it  for  the  purpose  of  fumigation  is  by 
the  action  of  dilute  sulphuric  acid  upon  potassium  cyanid,  in  the  fol- 
lowing proportions : 

Potassium  cyanid 1.0     part 

Sulphuric  acid 1.5     parts 

Water    2.25  parts 

The  first  step  is  to  dilute  the  acid,  which  is  done  by  adding  the 
acid  to  water  in  a  vitrified  clay  jar  or  receptacle  capable  of  withstand- 
ing the  heat.  The  whole  amount  of  cyanid  must  be  put  into  the  acid  at 
once.  As  the  evolution  of  the  gas  is  very  rapid,  the  operator  should 
be  ready  to  leave  the  spot  immediately.  As  pointed  out  by  Fulton,  it 
is  convenient  to  tie  the  cyanid  up  in  a  bag  made  of  cheese  cloth  or  tissue 
paper,  which  is  lowered  into  the  acid  by  a  cord  passing  outside  of  the 
room.  The  amount  of  gas  used  for  plant  fumigation,  expressed  in  terms 
of  cyanid,  is  about  1  ounce  per  100  cubic  feet;  about  the  same  quantity 
is  effective  as  an  insecticide  in  rooms  and  confined  spaces.  Hydrocyanic 
acid  gas  is  quite  as  efi'ective  as  sulphur  dioxid,  is  not  destructive,  is 
reasonably  cheap,  and  is  certain  in  its  action,  but  its  poisonous  nature 
is  such  a  serious  drawback  that  it  has  a  limited  place  as  an  insecticide 
in  public  health  Avork.     (See  page  1144.) 

Bisulphid  af  Carbon. — Bisulphid  of  carbon  (CSo)  is  a  very  efficient 
insecticide,  but  a  dangerous  one,  on  account  of  its  inflammable  and  ex- 
plosive nature.  It  quickly  kills  mosquitoes,  roaches,  flies,  ants,  and 
insects  of  all  kinds,  as  well  as  rats,  mice,  and  squirrels.  When  pure  it 
is  a  mobile,  colorless  liquid  with  an  agreeable  ethereal  odor,  but  often 
it  has  a  more  or  less  fetid  odor  from  the  presence  of  other  volatile 
compounds.  The  liquid  must  be  kept  in  well-stoppered  bottles  in  a  cool 
place,  and  away  from  the  light  and  fire.  It  evaporates  rapidly  at  ordi- 
nary temperatures,  so  that  in  using  this  substance  in  a  confined  space  it 
is  sufficient  to  pour  it  into  open  pans.     Carbon  bisulphid  is  very  in- 


INSECTICIDES  217 

flammable — more  so  than  ether — and  burns  with  a  pale  blue  flame 
yielding  sulphur  dioxid  and  carbon  dioxid  or  monoxid.  In  its  use 
every  precaution  must  be  taken  to  see  that  there  is  no  fire,  lighted 
cigar,  etc.,  in  or  about  the  field  of  operation.  On  account  of  its  poison- 
ous nature,  if  used  in  a  house  or  other  inhabited  structure,  the  rooms 
must  be  thoroughly  aired  after  its  use. 

According  to  Hinds,  shallow  tin  pans  or  plates  make  good  evaporat- 
ing dishes  for  carbon  bisulphid.  The  larger  the  evaporating  area  the 
better.  About  one  square  foot  of  evaporating  surface  is  used  to  every 
25  square  feet  of  floor  area,  and  one-half  to  one  pound  of  the  liquid 
carbon  bisulphid  is  used  for  each  square  foot  of  evaporating  surface. 
These  figures,  of  course,  are  only  suggestive  and  approximate.  The 
pans  should  be  placed  as  high  in  the  room  as  possible,  since  the  vapor 
is  so  heavy  that  it  settles  rapidly.  Care  should  be  taken  when  placing 
the  pans  to  see  that  they  are  nearly  level  so  as  to  hold  the  liquid,  though 
ordmarily  no  particular  harm  will  be  done  if  some  of  it  is  spilled.  It 
should  not  be  found  necessary  to  lose  time  in  adjusting  such  things  after 
the  operation  has  begun. 

Carbon  bisulphid  is  being  extensively  used  in  California  in  the  plague 
campaign.  A  piece  of  waste  the  size  of  an  orange  is  saturated  with 
the  liquid  and  the  wet  ball  placed  in  the  mouth  of  the  squirrel  hole. 
Wet  clay  is  then  stamped  into  the  warren  so  that  the  gas  which  is 
generating  may  have  no  opportunity  to  escape.  All  of  the  holes  of 
the  burrows  are  treated  in  this  way.  In  some  instances  the  ball  is 
placed  deeply  in  the  hole  and  then  ignited.  This  is  more  or  less  un- 
certain, as  an  explosion  occurs,  and,  while  the  gas  is  thus  disseminated, 
its  action  only  covers  a  limited  period  of  time,  and  is,  therefore,  not  as 
certain  as  simply  allowing  the  carbon  bisulphid  to  evaporate.  It  not  only 
kills  the  squirrels,  but  also  the  fleas  on  them.  Carbon  tetrachlorid  may 
be  used  in  place  of  carbon  bisulphid.  It  is  about  as  poisonous  but  neither 
inflammable  nor  explosive. 

Petroleum. — Petroleum,  kerosene,  or  coal  oil  is  a  very  valuable  insec- 
ticide, but  of  limited  application,  as  it  must  be  used  in  liquid  form. 
As  a  remedy  for  mosquitoes  it  is  applied  in  the  proportion  of  about  1 
ounce  to  15  square  feet  of  water  surface.  It  should  form  a  uniform 
film  over  the  surface,  and  will  then  destroy  the  larvae  and  pupae  of 
the  mosquito  and  the-  adult  females  coming  to  the  water  to  lay  their 
eggs.  The  oil  must  be  renewed  every  week  or  two,  depending  upon 
the  temperature  and  other  conditions.  A  light  grade  of  fuel  oil  is  best 
for  this  purpose  (see  page  224). 

Petroleum  is  also  useful  against  roaches,  bedbugs,  fleas,  lice,  and 
other  insect  vermin  when  used  by  direct  application  or  by  spraying, 
either  in  the  form  of  the  pure  oil  or  as  an  emulsion.  Petroleum  is 
very  efficient  against  fleas.     Frequent  application  to  the  floor  or  other 


218  INSECT-BORNE    DISEASES 

places  will  keep  away  ants,  and  by  direct  application  to  the  breeding, 
feeding,  and  traveling  places  it  is  a  useful  remedy  against  house- 
hold vermin  in  general.  By  direct  application  to  the  head  or  other 
parts  affected,  coal  oil  is  the  cheapest  and  most  effective  remedy 
for  lice. 

Emulsion  of  crude  petroleum  for  application  to  the  skin  of  animals 
or  to  trees,  or  other  plants,  or  for  general  insecticidal  purposes  is  made 
from  the  formula  of-T.  M.  Price: 

Crude  petroleum 2  gallons 

Water   V2  gallon 

Hard  soap   %  pound 

Dissolve  the  soap  in  the  water  with  the  aid  of  heat.  To  this  add 
the  crude  petroleum;  mix  with  a  spray  pump  or  shake  vigorously  and 
dilute  with  the  desired  amount  of  water.  The  emulsion  of  crude  petro- 
leum made  according  to  this  modified  formula  remains  fluid,  and  can 
be  easily  poured.  It  will  stand  indefinitely  without  any  tendency 
toward  separation  of  the  oil  and  water,  and  can  be  diluted  in  any  pro- 
portion with  cold  soft  water. 

Gasoline,  naplitha,  and  benzine  are  among  the  best  pulicides,  and  as 
such  are  extensively  used  to  kill  lice  in  typhus  fever  campaigns. 

Arsenic. — The  arsenical  compounds,  according  to  Marlatt,^  have  sup- 
planted practically  all  other  substances  as  a  food  poison  for  biting  in- 
sects. The  two  arsenicals  in  most  common  use  obtainable  everywhere 
are  arsenate  of  lead  and  Paris  green.  Scheele's  green,  or  arsenate  of 
copper,  is  less  known  and  less  easily  obtainable,  but  in  some  respects 
is  better  than  Paris  green.  The  use  of  powdered  white  arsenic  is  not 
recommended  on  account  of  its  corrosive  action,  as  well  as  the  fact  that 
it  is  apt  to  be  mistaken  for  harmless  substances. 

The  arsenical  poisons  may  be  applied  in  one  of  three  ways:  (1)  in 
suspension,  as  poisoned  waters,  mainly  in  the  form  of  sprays;  (2)  as  a 
dry  powder  blown  or  dusted  about  the  infested  areas ;  or  ( 3 )  as  poisoned 
bait. 

It  must  be  remembered  that  the  arsenicals  are  very  poisonous,  and 
should  be  so  labeled,  and  care  taken  to  prevent  accidents. 

Paris  geeen  is  a  definite  chemical  compound  of  arsenic,  copper,  and 
acetic  acid  (acetoarsenite  of  copper),  and  should  have  a  nearly  uniform 
composition.  It  is  rather  a  coarse  powder,  or,  more  properly  speaking, 
crystal,  and  settles  rapidly  in  water,  which  is  its  greatest  fault  so  far  as 
the  making  of  suspensions  of  this  substance  is  concerned. 

Scheele's  geeen  is  similar  to  Paris  green  in  color  and  differs  from 
it  only  in  lacking  acetic  acid;  in  other  words,  it  is  simply  arsenite  of 

^Farmers'  Bulletin  No.  19,  U.  S.  Dept.  of  Agriculture. 


mSECTICIDES  219 

copper.  It  is  a  finer  powder  than  Paris  green,  and,  therefore,  is  more 
easily  kept  in  suspension. 

Arsenious  oxid  (AsgOg)  is  used  in  dips  to  destroy  ticks  (page  288). 

Arsenite  of  lead  is  prepared  by  combining,  approximately,  3  parts 
of  the  arsenite  of  soda  with  7  parts  of  the  acetate  of  lead  (white  sugar 
of  lead)  in  water.  These  substances,  when  pulverized,  unite  readily 
and  form  a  white  precipitate,  which  is  more  easily  kept  suspended  in 
water  than  any  of  the  other  arsenical  poisons.  Its  use  is  advised  where 
excessive  strengths  are  not  desirable,  and  upon  delicate  plants,  where 
otherwise  scalding  is  likely  to  result. 

An  average  of  one  pound  of  either  Paris  green  or  Scheele's  green,  or 
London  purple  to  150  gallons  of  water  is  a  good  strength  for  general 
purposes  in  using  the  wet  method.  The  powder  should  first  be  made 
up  into  a  thin  paste  in  a  small  quantity  of  water,  and,  if  the  suspen- 
sion is  to  be  used  upon  plants,  vegetables,  or  about  foliage,  an  equal 
amount  of  quicklime  should  be  added  to  take  up  the  free  arsenic  and 
remove  or  lessen  the  danger  of  scalding. 

For  the  distribution  of  dry  poison  the  arse'nicals  are  diluted  with 
10  parts  of  flour,  lime,  or  dry  gypsum. 

The  following  mixtures  are  used  in  the  form  of  sprays,  to  destroy 
insects  and  fungi  upon  plants.^  The  arsenate  of  lead  mixture  has  been 
much  used  in  Massachusetts  with  success  against  the  gipsy  moth  and 
other  destructive  insects  upon  trees  and  plants.  These  mixtures  are 
equally  useful  as  insecticides  wherever  sprays  or  local  applications  are 
practicable. 

AESENATE  OF  LEAD 

Arsenate  of  soda  (5  per  cent,  strength),  4  ounces. 
Acetate  of  lead,  11  ounces. 
Water,  100  gallons. 

Put  the  arsenate  of  soda  in  2  quarts  of  water  in  a  wooden  pail,  and 
the  acetate  of  lead  in  four  quarts  of  water  in  another  wooden  pail. 
When  both  are  dissolved,  mix  with  the  rest  of  the  water.  Warm  water 
in  the  pails  will  hasten  the  process.  For  the  elm-leaf  beetle  use  10 
instead  of  100  gallons  of  water. 

A  number  of  ready-made  arsenates  of  lead  are  now  on  the  market, 
and,  except  when  very  large  amounts  are  needed,  it  will  probably  prove 
cheaper  to  buy  the  prepared  material  than  to  make  it.  With  this 
ready-made  material  take  3  pounds  to  50  gallons  of  water  for  codling 
moth,  and  5  pounds  to  50  gallons  to  the  elm-leaf  beetle  and  on  potatoes. 

^  From  Bulletin  No.  123,  April,  1908,  of  the  Massachusetts  Agricultural 
Experiment  Station  by  Stone  and  Ferald. 


220  INSECT-BOENE    DISEASES 

ARSENITE  OF  LIME 

White  arsenic,  2  pounds. 
Sal-soda,  8  pounds. 
Water,  2  gallons. 

Boil  till  the  arsenic  all  dissolves — about  45  minutes.  Make  up  the 
water  lost  by  boiling  and  place  in  an  earthen  dish.  For  use  take  one 
pint  of  this  stock,  2  pounds  freshly  slaked  lime,  and  45  gallons  water, 
and  spray. 

KEROSENE  EMULSION 

Hard  soap,  shaved  fine,  1/2  pound. 
Water,  1  gallon. 
Kerosene,  2  gallons. 

Dissolve  the  soap  in  the  water,  which  should  be  boiling;  remove 
from  the  fire  and  pour  it  into  the  kerosene  while  hot.  Churn  this  with 
a  spray  pump  till  it  changes  to  a  creamy,  then  to  a  soft,  butter-like 
mass.  Keep  this  as  a  stock,  using  one  part  in  nine  of  water  for  soft- 
bodied  insects,  such  as  plant  lice,  or  stronger  in  certain  cases. 

EESIN-LIME   MIXTURE 

Pulverized  resin,  5  pounds. 
Concentrated  lye,  1  pound. 
Fish  or  other  animal  oil,  1  pint. 
Water,  5  gallons. 

Place  the  oil,  resin  and  one  gallon  of  hot  water  in  an  iron  kettle 
and  heat  till  the  resin  softens;  then  add  the  lye  and  stir  thoroughly; 
now  add  4  gallons  of  hot  water  and  boil  till  a  little  will  mix  with  cold 
water  and  give  a  clear,  amber-colored  liquid;  add  water  to  make  up  5 
gallons.    Keep  this  as  a  stock  solution.     For  use  take : 

Stock  solution,  1  gallon. 
Water,  16  gallons. 
Milk  of  lime,  3  gallons. 
Paris  green,  14  pound. 

BORDEAUX   MIXTURE 

Copper  sulphate  (blue  vitriol),  4  pounds. 
Lime  (unslaked),  4  pounds. 
Water,  25  to  50  gallons. 


MOSQUITOES  221 

Dissolve  the  copper  in  hot  or  cold  water,  using  a  wood  or  earthen 
vessel.  Slake  the  lime  in  a  tub,  adding  the  water  cautiously  and  only 
in  sufficient  amount  to  insure  thorough  slaking.  After  thoroughly 
slaking,  more  water  can  be  added  and  stirred  in  until  it  has  the  con- 
sistency of  thick  cream.  When  both  are  cold,  dilute  each  to  the  re- 
quired strength  and  pour  both  together  in  a  separate  receptacle  and 
thoroughly  mix.  Before  using,  strain  through  a  fine  mesh  sieve  or  a 
gunny  cloth;  the  mixture  is  then  ready  for  use. 

If  the  amount  of  lime  in  the  Bordeaux  mixture  is  insufficient  there 
is  danger  of  burning  tender  foliage.  In  order  to  obviate  this,  the  mix- 
ture can  be  tested  with  a  knife  blade  or  with  ferrocyanid  of  potassium 
(1  oz.  to  5  or  6  oz.  of  water).  If  the  amount  of  the  lime  is  insufficient, 
copper  will  be  deposited  on  the  knife  blade,  while  a  deep  brownish-red 
color  will  be  imparted  to  the  mixture  when  ferrocyanid  of  potassium 
is  added.  Lime  should  be  added  until  neither  reaction  occurs.  A  slight 
excess  of  lime,  however,  is  desirable,  and  it  is  seldom  one  has  to  apply 
these  tests.  The  Bordeaux  mixture  is  a  good  fungicide,  but  is  less  useful 
as  an  insecticide. 

MOSQUITOES 

Mosquitoes  differ  markedly  in  their  habits.  Some  species  may  be 
classed  as  domestic  animals  because  they  are  commonly  or  almost  ex- 
clusively found  in  or  close  to  human  habitations.  This  is  notably  the 
case  with  Stegomyia  calopus,  the  yellow  fever  mosquito ;  Culex  pungens, 
the  intermediary  for  Filaria  hancrofti  (filariasis) ;  and  Culex  fatigans, 
the  carrier  of  dengue  fever.  The  sylvan  or  wild  mosquitoes,  of  which 
the  Culex  soUicitans,  the  common  salt  marsh  mosquito  of  our  Atlantic 
coast,  is  a  well-known  example,  are  seldom  met  with  in  human  habita- 
tions. A  third  or  semi-domestic  class  may  be  encountered  either  in 
or  near  houses,  or  in  fields  or  swamps.  This  class  includes  the  malarial 
mosquitoes  belonging  to  the  genus  Anopheles. 

The  adult  mosquito  may  be  carried  to  considerable  distances  by 
winds;  but  of  its  own  volition  it  does  not  ordinarily  travel  outside  of 
a  radius  of  half  a  mile  from  its  breeding  place.  Most  species  do  not 
fly  nearly  so  far.  This  means  that  the  destruction  of  all  breeding  places 
within  a  comparatively  small  radius  of  a  habitation  will  rid  it  of  all 
but  those  mosquitoes  which  are  blown  in  by  the  winds  from  more  or 
less  distant  marshes,  or  which  are  brought  in  the  vessels  and  vehicles 
of  trade  and  travel. 

Life  History  and  Habits. — Mosquitoes  pass  through  four  stages:  (1) 
the  egg  or  embryo,  (2)  the  larva,  (3)  the  pupa,  and  (4)  the  imago 
or  adult  winged  insect.  The  egg,  larval,  and  pupal  stages  are  aquatic. 
Mosquitoes  never  breed  in  damp  grass,  weeds,  or  bushes,  as  is  popularly 


322  INSECT-BORNE    DISEASES 

supposed,  but  the  winged  insects  frequently  rest  and  hide  in  vegeta- 
tion. The  different  species  of  mosquitoes  not  only  differ  markedly  in 
their  habits,  but  differ  considerably  in  the  character  of  their  breeding 
places.  The  domestic  species,  such  as  the  yellow  fever  mosquito  and 
Culex  pungens,  may  be  found  breeding  in  any  collection  of  water  in  or 
about  houses.  Thus,  they  have  been  found  in  discarded  tin  cans,  bottles, 
and  broken  crockery  on  the  garbage  heap;  in  buckets,  tubs,  barrels, 
cisterns,  and  wells;  in  baptismal  fonts;  in  flower  pots  and  sagging  roof 
gutters ;  in  street  and  roadside  puddles,  gutters,  and  ditches ;  in  cesspools 
and  sewers. 

The  semi-domestic  mosquitoes,  to  which  the  malarial-bearing  insects 
belong,  may  occasionally  be  fovmd  breeding  in  tin  cans,  barrels,  hoof 
prints,  post  holes,  and  hollows  in  trees  or  tree  stumps,  but  they  usually 
prefer  grass-bordered  pools,  slowly  flowing  ditches,  the  margins  of  lakes 
and  streams,  even  such  as  are  stocked  with  fish,  provided  the  margins 
are  shallow  or  are  more  or  less  choked  with  reeds  and  water  plants  so 
that  the  fish  cannot  reach  them.  The  sylvan  or  wild  mosquitoes  select 
breeding  places  of  much  the  same  character  as  do  the  semi-domestic 
species,  with  which  they  are  not  infrequently  found  associated,  except 
that  such  breeding  places  are  more  or  less  remote  from  human 
habitations,  in  woods,  swamps,  and  fresh  or  salt  (brackish)  coastal 
marshes. 

Male  mosquitoes  are  vegetarians.  The  females  of  many  species 
have  developed  a  taste  for  blood,  and,  indeed,  blood  has  become  indis- 
pensable to  nearly  all  for  the  full  development  of  their  eggs.  This 
is  the  case  with  Stegomyia  calopus.  Eemembering  how  all-important 
the  generative  instinct  is,  we  can  now  well  understand  why  the  yellow 
fever  mosquito,  for  example,  will,  when  disturbed,  return  again  and 
again  in  an  endeavor  to  obtain  her  fill  of  this  life-giving  fluid. 

The  mosquito  lays  her  eggs  upon  the  surface  of  the  water,  and 
these,  depending,  upon  the  species,  either  float  separately  on  their  sides 
{Stegomyia  calopus  and  Anopheles),  or  adhere  together  in  irregular, 
raft-like  masses  {Culex).  In  a  day  or  two,  under  ordinary  conditions, 
the  eggs  hatch  out  into  larvae  or  "wiggle-tails."  Although  the  larva 
is  an  aquatic  animal,  it  is  a  true  air-breather.  The  larva  of  Anopheles 
ordinarily  rests  and  feeds  at  the  surface,  where  it  lies  in  an  almost 
horizontal  position,  its  tail  and  dorsal  bristles  touching  the  surface 
film,  while  it  breathes  through  a  breathing  siphon,  which  is  very  short  and 
insignificant  in  appearance. 

The  larvae  of  the  other  species  move  about  more  or  less,  actively 
searching  for  food,  but  at  intervals  of  a  minute  or  two  they  may  be 
seen  to  come  to  the  surface  for  air,  where  they  hang,  head  down,  at- 
tached by  their  more  or  less  prominent  conical  breathing  tubes  to  the 
surface  film.     The  mosquito  remains  in  the  larval  stage  about  a  week 


MOSQUITOES  223 

and  is  then  transformed  into  a  curiously  shaped  creature  known  as  the 
pupa. 

The  pupa  has  no  mouth  and  does  not  feed.  It  remains  quietly  at 
the  surface  except  when  disturbed.  It  breathes  through  a  pair  of  trum- 
pet-shaped tubes,  which  project  from  the  dorsum  of  the  thorax.  The 
pupal  stage  usually  lasts  two  or  three  days,  and  is  terminated  by  the 
emergence  of  the  adult  winged  insect  (imago)  from  its  pupal  case 
through  a  rent  in  the  region  of  the  breathing  tubes. 

The  time  from  the  laying  of  the  egg  to  the  winged  insect  may,  there- 
fore, be  as  short  as  nine  days.  The  time  depends  upon  the  tempera- 
ture and  the  abundance  of  the  food  supply.  Warmth  favors  and  cold 
retards;  therefore,  mosquitoes  are  most  abundant  during  the  summer, 
late  spring,  and  early  fall  months  in  our  climate.  In  the  tropics  the 
wild  species  become  more  abundant  during  the  wet  season. 

The  way  in  which  mosquitoes  manage  to  pass  through  the  rigors  of 
the  winter  probably  varies  with  the  different  species.  Some,  like  the 
malarian  Anopheles,  hide  in  sheltered  cellars  or  dark  nooks,  or  hibernate 
in  other  out-of-the-way  places.  Other  species  survive  through  the  power 
of  the  larva  or  egg  to  resist  cold,  for  the  larvae  or  eggs  of  some  species 
will  hatch  even  after  they  have  been  frozen. 

THE  DESTRUCTION  OF  MOSQUITOES^ 

The  life  of  a  mosquito  may  be  divided  into  an  aquatic  and  an  aerial 
stage,  the  former  including  the  egg,  larva,  and  pupa,  and  the  latter 
the  adult  winged  insect.  Accordingly,  the  measures  aimed  at  the  de- 
struction of  the  mosquito  naturally  fall  into  two  classes:  (a)  those  di- 
rected against  the  larva  and  pupa — the  aquatic  stages — and  (b)  those 
directed  against  the  winged  insect. 

For  the  extermination  of  mosquitoes  the  most  effective  measures 
are  those  which  aim  to  destroy  their  breeding  places,  and  thus  prevent 
their  multiplication.  For  the  best  results  both  individual  and  com- 
munal effort  are  necessary,  but  the  importance  of  individual  effort  alone 
cannot  be  too  much  emphasized.  The  individual,  by  attacking  the  prob- 
lem on  his  own  premises,  grounds,  or  estate,  can  not  only  do  much  to 
rid  his  own  immediate  neighborhood  of  mosquitoes,  and  thereby  in- 
crease his  own  comfort  and  guard  against  disease,  but  the  example  thus 
set  will  perhaps  stimulate  his  less  enterprising  neighbor. 

To  insure  success  it  is  important  to  know  the  habits  and  breeding 
places  of  the  particular  species  that  it  is  desired  to  suppress. 

Natural  Breeding  Places. — Natural  collections  of  water  which  may 
serve  as  breeding  places  are  best  dealt  with  by  filling  in  or  by  draining. 

*Le  Prince  and  Orenstein:  Mosquito  Control  in  Panama.  J.  P.  Putnam's. 
Sons,  New  York,   1916. 


^24  INSECT-BOENE    DISEASES 

In  this  way  tkey  are  disposed  of  once  for  all.  For  filling,  inorganic 
refuse,  such  as  cinders  and  ashes,  may  be  employed,  or  sufficient  earth 
may  be  dug  from  a  nearby  knoll  or  hill,  care  being  observed  that  in  so 
doing  a  depression  capable  of  holding  water  is  not  made.  Low  marshy 
lands  adjacent  to  rivers,  lakes,  or  the  sea  may  be  filled  by  pumping  silt 
or  sand. 

When  filling  is  not  practicable,  good  and  permanent  results  may 
be  obtained  by  drainage.  As  a  rule,  the  draining  of  ponds,  pools,  or 
marshes  is  the  simpler  and  cheaper  method.  By  the  draining  of  marshes 
is  meant  the  draining  of  the  pools  of  stagnant  water,  or  in  the  case  of 
coastal  marshes  the  draining  of  the  stagnant  fishless  pools  that  are  be- 
yond the  reach  of  the  ordinary  tides;  it  does  not  necessarily  include  the 
draining  of  the  water-soaked  soil  itself.  The  underdraiuing  of  wide 
acreages  of  our  arable  land  in  the  Middle  West  has  been  very  effective 
in  suppressing  the  malarial  mosquito.  Marshy  lands  may  be  drained 
simply  by  means  of  ditches.  These  must  be  dug  of  sufficient  depth  to 
completely  empty  the  pools  under  treatment  and  have  sufficient  fall  to 
prevent  stagnation  in  the  course  of  the  ditch  itself.  Where  a  sufficient 
fall  is  not  obtainable  fishless  pools  may  be  connected  with  those  con- 
taining fish  or  with  a  neighboring  stream,  so  that  the  fish  may  freely 
enter.  Mosquito  breeding  places  in  the  pools  in  coastal  marshes  may 
be  suppressed  by  connecting  them  with  tide  water,  so  that  they  may 
be  freely  scoured  by  the  daily  tides.  Ditches  should  have  straight  sides 
and  must  be  inspected  at  frequent  intervals,  and  care  must  be  taken  to 
see  that  they  do  not  become  choked. 

Fish  are  among  the  most  effective  of  the  natural  enemies  of  the 
mosquito.  The  fish  may  be  admitted  to  ponds  and  pools  in  the  man- 
ner just  described,  or  the  ponds,  pools,  ornamental  lakes,  and  fountains 
may  be  directly  stocked  with  minnows  or  gold  fish.  The  margins  of 
pools,  rivers,  and  other  bodies  of  water  must  be  kept  free  of  reeds 
and  water  plants,  so  as  to  permit  the  fish  to  reach  the  edges — a  favorite 
breeding  place  for  mosquitoes.  One  of  the  very  best  means  of  clear- 
ing the  land  of  the  numerous  small  natural  collections  of  water  is  to  place 
it  under  cultivation. 

When  radical  measures,  such  as  filling  in  or  draining,  are  not  prac- 
ticable, resort  may  then  be  had  to  coal  oil.  Coal  oil  upon  the  surface 
of  the  water  acts  mainly  by  suffocating  the  larvae  and  pupae.  A  light 
quality  of  oil  should  be  used,  and  it  may  be  poured  upon  the  surface 
from  an  ordinary  sprinkling  pot,  or  the  surface  may  be  sprayed  with 
a  hose.  Along  the  banks  of  ponds,  lakes,  and  slowly  moving  streams 
with  shallow  margins  containing  vegetation,  which  offer  favorite  breed- 
ing places  for  the  mosquito,  the  oil  may  be  applied  with  a  mop.  This 
practice  is  laborious,  but  effective.  Sufficient  oil  should  be  used  to 
.cover  the  entire  surface  with  a  thin  film.    As  the  oil  is  volatile,  it  may 


MOSQUITOES  335 

disappear  within  a  few  days.  Furthermore,  the  film,  which  should  be 
intact  to  be  effective,  may  be  broken  by  winds.  A  strong  wind  will  blow 
all  of  the  oil  to  one  side,  thereby  entirely  defeating  the  object  desired. 
It  is,  therefore,  important  to  repeat  the  oiling  regularly  at  intervals 
of  not  more  than  one  week,  and  as  often  in  addition  as  necessary. 
Oiling,  though  fairly  effective  when  properly  carried  out,  is  only  a  tem- 
porary expedient,  and  in  the  end  is  rather  expensive.  (See  also  page 
217.) 

In  Panama  a  larvicide  is  being  used  which  is  made  as  follows :  150 
gallons  of  crude  carbolic  acid  having  a  specific  gravity  not  greater  than 
0.97  and  containing  not  less  than  30  per  cent,  tar  acids,  is  heated  in  an 
iron  tank  with  a  steam  coil  to  a  temperature  of  212°  F.,  then  200  pounds 
of  powdered  or  finely  broken  common  resin  is  poured  in.  The  mixture  is 
kept  at  a  temperature  of  212°  F.  Thirty  pounds  of  caustic  soda  dissolved 
in  60  gallons  of  water  are  then  added,  and  the  solution  is  kept  at  the 
same  temperature  until  a  perfectly  dark  emulsion  without  sediment  is 
formed.  The  mixture  is  thoroughly  stirred  from  the  time  the  resin 
is  added  until  the  end.  One  part  of  this  emulsion  to  10,000  parts  of 
water  is  said  to  kill  Anopheles  larvae  in  less  than  half  an  hour,  while  1 
part  to  5,000  parts  of  water  will  kill  them  in  from  5  to  10  minutes. 

The  Panama  larvicide  is  mixed  with  5  parts  of  water  and  sprayed 
upon  pools  or  along  the  banks  of  streams.  This  larvicide  added  to  5 
parts  of  crude  petroleum  favors  its  spread  upon  the  surface  of  the  water. 
A  good  method  is  to  place  the  mixture  in  a  barrel  and  permit  it  to 
drip  upon  the  surface  of  the  stream  or  pond  to  be  treated. 

Other  larvicides  that  may  be  used  in  water  not  used  for  drinking 
purposes  are :  sulphuric,  hydrochloric,  and  other  acids,  potassium  per- 
manganate, sulphate  of  copper,  sulphate  of  iron,  bichlorid  of  mercury, 
carbolic  acid,  anilin  products,  or  coal  tar.  They  must  be  used  in  rela- 
tively large  amounts  to  be  effective,  and  frequently  renewed  according 
to  circumstances. 

No  body  of  water  is  too  small  for  a  mosquito  nursery.  They  breed 
in  puddles  by  the  roadside ;  in  water  that  accumulates  in  furrows  in 
gardens  or  fields,  especially  in  clayey  soil;  in  street  gutters  and  house 
gutters ;  in  holes  in  rocks ;  in  hollows  in  trees,  in  pitcher  plants,  and  any- 
where that  a  gill  of  water  is  allowed  to  stand. 

Artificial  Breeding  Places. — The  permanent  elimination  of  artificial 
breeding  places  for  mosquitoes  in  a  city  depends  first  of  all  upon  provid- 
ing a  good  quality  and  sufficient  quantity  of  potable  water  by  means  of  a 
modern  closed  system.  This  will  permanently  do  away  with  the  neces- 
sity of  cisterns,  barrels,  and  tubs  for  the  storage  of  water  about  the 
premises.  When  domestic  storage  is  a  necessity,  care  must  be  taken  to 
prevent  the  mosquito  from  gaining  access  to  the  water.  The  water  bar- 
rels should  be  provided  with  tightly  fitting  covers.    Burlap,  sheeting,  or 


226  mSECT-BOENE    DISEASES 

several  thicknesses  of  cheese-cloth,  or,  better,  wire  screening  held  in 
place  by  a  well-fitting  hoop,  serve  this  purpose  very  well.  Wooden 
covers  are  unsatisfactory,  for  they  rarely  fit  accurately  enough  to  keep 
out  the  mosquito,  and  this  defect  is  enhanced  by  the  warping  of  the 
wood,  which  usually  makes  an  old  cover  worse  than  useless.  More 
satisfactory  than  the  wooden  cover  is  one  made  of  light  galvanized 
sheet  iron,  the  central  portion  of  which  may  be  made  of  wire  gauze.  The 
rim  of  the  barrel  should  be  trimmed  to  remove  any  irregularities  that 
might  prevent  the  cover  from  fitting  evenly  all  around.  Whatever  the 
form  of  the  cover  employed,  it  should  not  be  removed  except  for  cleaning 
or  refilling  the  barrel.  The  water  should  be  drawn  from  a  spigot. 
Where  the  water  is  very  turbid  and  must  undergo  sedimentation  before 
being  used,  several  barrels  should  be  provided  for  its  storage  and  the 
water  used  from  each  barrel  in  turn.  In  such  a  case  the  spigot  should 
be  placed  about  a  foot  from  the  bottom,  so  that  the  sediment  need  not 
be  disturbed  as  the  water  is  drawn  off  for  use.  Wells  should  be  pro- 
vided with  tight  covers  and  the  water  drawn  by  pumps. 

Cisterns  and  tanks  should  also  be  provided  with  accurately  fitting 
covers,  and  should  be  inspected  frequently  for  seams  and  cracks  result- 
ing from  warping  and  shrinking  of  the  wood.  To  guard  against  this 
loophole,  wire  gauze  should  be  used  to  screen  the  joint  between  the  tank 
and  its  cover.  The  gauze  should  include  about  one  foot  of  the  tank 
and  overlap  well  upon  the  cover.  The  inlet  to  the  tank  or  cistern 
should  be  provided  with  a  cap  of  copper  meshed  wire  gauze  which  may 
be  protected  by  another  and  coarser  meshed  cap  of  stout  wire,  to  pre- 
vent its  choking  with  leaves,  etc.  As  an  additional  precaution,  the  in- 
let pipe  should  be  long  and  extend  well  below  the  water  level.  In  cases 
of  emergency,  as  in  times  of  epidemics  of  yellow  fever  or  dengue,  where 
the  permanent  measures  for  preventing  mosquito  breeding  have  been 
neglected,  the  surface  of  the  water  in  barrels,  tanks,  and  cisterns  may 
be  covered  with  some  neutral  non-volatile  oil  which  does  not  impart  a 
taste  to  the  water. 

Cesspools  and  privy  vaults  should  be  done  away  with  and  replaced 
with  dry  earth  closets  or  a  water  carriage  cistern.  Where  this  has  not 
been  done  they  may  be  frequently  and  copiously  oiled. 

Among  the  artificial  breeding  places  for  mosquitoes  may  be  men- 
tioned chicken-pens  in  poultry  yards;  water  cups  on  the  frames  of 
grindstones;  baptismal  fonts;  tin  cans  or  broken  bottles  in  back  yards; 
the  catch  basins  of  sewers;  the  water  that  stands  in  sagging  house  gut- 
ters ;  flower-pots,  fire  buckets,  and  similar  places. 

Screening. — Mosquito  screens  are  the  obvious  and  most  effective 
single  measure  for  personal  prophylaxis  where  disease-carrying  mosqui- 
toes exist.  In  order  to  be  effective  the  screening  must  be  intelligently 
carried  out  with  careful  attention  to  details.     The  screen  itself  must 


MOSQUITOES  227 

be  sufficiently  close  to  keep  out  the  mosquitoes.  Some  of  them  are  able 
to  squeeze  through  surprisingly  narrow  chinks.  I  was  able  to  demon- 
strate, in  the  experimental  work  at  Vera  Cruz,  that  the  Stegomyia  mos- 
quito can  pass  a  metal  wire  screen  containing  16  strands  or  15  meshes  to 
the  inch,  but  cannot  pass  one  containing  20  strands  or  19  meshes  to  the 
inch.  When  the  screen  consists  of  a  fabric  which  is  apt  to  pull  out  of 
shape  so  that  some  of  the  meshes  are  larger  than  others,  it  is  advisable 
to  use  a  net  woven  closer  than  20  strands  to  the  inch.  Experience  in 
malarial  and  yellow  fever  districts  has  taught  this  lesson,  so  that  it  is 
customary  in  those  countries  to  use  a  rather  closelj'  woven  material  re- 
sembling nainsook.  Metal  screens  made  of  iron  wire  are  cheapest  only 
when  first  cost  is  considered.  They  hardly  last  a  season  unless  painted, 
in  which  case  the  size  of  the  mesh  is  considerably  reduced  and  inter- 
feres with  ventilation,  a  serious  objection  in  hot  weather  or  a  tropical 
climate.  Mesh  made  of  galvanized  iron  wire  has  a  greater  durability. 
Screens  made  of  brass  or  bronze  are  expensive,  but  cheap  in  the  long 
run,  as  they  are  found  to  last  almost  indefinitely. 

The  screening  should  include  the  entire  house,  or  at  least  those 
parts  that  are  occupied.  In  the  tropics  it  is  better  to  screen  the  gal- 
leries than  each  individual  window.  In  any  case,  frequent  and  repeated 
inspection  should  be  made  to  discover  breaks  in  the  screen  or  openings 
due  to  warping  of  the  woodwork.  In  screening  care  must  be  exercised 
not  to  overlook  fireplaces,  ventilators,  and  other  openings.  The  door 
should  be  guarded  by  a  screened  vestibule  of  such  a  depth  as  to  make 
it  impossible  for  a  person  to  hold  both  doors  open  at  the  same  time. 
The  screen  door  should  open  outward  and,  if  possible,  should  be  exposed 
to  the  direct  sunlight  during  the  day  without  vines  or  nearby  vegeta- 
tion of  any  kind  to  protect  and  lodge  the  mosquitoes.  During  the  night 
the  door  should  not  be  in  an  artificial  light,  which  attracts  many  mos- 
quitoes. An  electric  fan  directed  outward  is  a  very  good  device  to  pre- 
vent mosquitoes  flying  through  the  doorway.  In  addition,  a  whisk- 
broom  or  feather  duster  should  hang  in  the  vestibule  to  brush  off  the 
insects  that  may  rest  upon  the  clothing.  A  screened  house  is  safe  only 
to  careful  and  intelligent  people. 

In  addition  to  screening  the  house,  mosquito  bars  over  the  bed  will 
be  found  necessary  in  mosquito-infested  places.  It  is  best  to  suspend  the 
mosquito  bar  from  the  ceiling  and  carefully  gather  the  bottom  together 
so  as  to  keep  the  insects  out  during  the  day  time.  At  night  the  bar 
should  be  carefully  tucked  in  around  the  bed  so  as  to  leave  no  openings. 
Mosquitoes  have  no  trouble  in  biting  through  the  meshes  of  the  bar, 
provided  a  restless  sleeper  comes  close  enough  to  it. 

Persons  who  are  required  to  go  out  at  night  in  a  malarious  district, 
or  who  must  expose  themselves  during  yellow  fever  times,  may  screen 
themselves  effectively  with  a  veil  of  mosquito  netting  hanging  from  a 


238  INSECT-BORNE    DISEASES 

broad-brimmed  hat  to  the  shoulders  and  chest.  The  hands  and  wrists 
may  be  protected  with  gloves,  and  the  ankles  with  leather  leggings  or 
other  suitable  mechanical  device. 

Volatile  Substances. — Spirits  of  camphor,  oil  of  pennyroyal,  and 
other  volatile  substances,  such  as  oil  of  peppermint,  lemon  juice,  or 
vinegar,  rubbed  upon  the  face  and  hands,  or  a  few  drops  on  the  pillow 
at  night,  may  keep  mosquitoes  away  only  for  a  time.  Oil  of  citronella 
is  one  of  the  best  known  substances  used  in  this  way.  Ordinarily  a 
few  drops  on  a  bath  towel  hung  over  the  head  of  the  bed  may  keep  some 
mosquitoes  away.  When  they  are  very  abundant  and  persist,  a  few 
drops  rubbed  on  the  face  and  hands  may  be  tried.  All  these  substances 
soon  lose  their  efficiency;  none  of  them  last  until  morning. 

The  diseases  known  to  be  conveyed  by  mosquitoes  are :  malaria 
(Anopheles  spp.)  yellow  fever  (Stegomyia  calopus),  filariasis  {Culex 
pungens),  dengue  {Culex  fatigans),  and  doubtless  others. 

MALARIA 

Malaria  is  one  of  the  most  prevalent  of  all  preventable  diseases;  it  is 
the  scourge  of  the  tropics.  The  cause  of  this  infection  was  one  of  the 
first  to  be  discovered  (Laveran,  1880),  and  its  mode  of  transmission 
was  one  of  the  most  brilliant  discoveries  in  sanitary  science  (Eoss, 
1895).  Despite  the  fact  that  we  have  more  exact  knowledge  of  malaria, 
considering  the  difficulties  of  the  subject,  than  perhaps  any  other  dis- 
ease, despite  the  fact  that  we  have  accurate  means  of  diagnosis  and  a 
ready  cure,  and  despite  the  fact  that  we  have  assured  measures  of  pre- 
vention, malaria  counts  its  victims  by  the  hundreds  of  thousands  annu- 
ally. In  geographic  distribution  malaria  extends  from  the  Arctic  circle 
to  the  Equator,  but  becomes  more  virulent  the  warmer  the  climate. 

At  least  three  separate  malarial  parasites  of  man  are  known,  namely : 
(1)  Plasmodium  malariae  (Laveran),  quartan  fever;  (3)  Plasmodium 
vivax  (Grassi  and  Filetti),  tertian  fever;  and  (3)  Plasmodium  falcip- 
arum (Welch),  estivoautumnal  or  tropical  malaria.  These  are  closely 
allied  hematocytozoa  or  blood  parasites.  They  produce  diseases  with 
well-defined  clinical  differences,  but  having  the  same  etiology  and  mode 
of  transference,  so  that,  as  far  as  prevention  is  concerned,  they  may 
be  regarded  as  one  infection. 

Many  species  of  animals  have  a  malarial-like  infection  closely  re- 
sembling malaria  in  man ;  for  example,  Texas  fever  of  cattle,  piroplas- 
mosis  of  dogs  and  sheep,  proteosoma  of  birds,  etc.  So  far  as  is  known, 
no  other  animal  than  the  Anopheles  "mosquito  is  subject  to  the  malarial 
parasites  pathogenic  for  man.  Both  man  and  the  mosquito  are  neces- 
sary to  complete  the  life  cycle  of  the  plasmodium.     Man  is  the  inter- 


MOSQUITOES  229 

mediate  host  harboring  the  asexual  phase,  and  the  mosquito  is  the  defin- 
itive host  harboring  the  sexual  phase  of  the  life  cycle  of  the  Plas- 
modium. 

Mosquito  Transmission. — It  is  now  definitely  known  that  in  nature 
malaria  is  transmitted  only  by  the  bite  of  the  Anopheles  mosquito.^ 
Experimentally,  the  infection  may  be  transferred  by  injecting  blood 
(containing  the  parasites)  of  one  person  into  the  system  of  another. 
Nearly  2,000  years  ago  Varro  and  Columbella  mentioned  the  possibility 
that  the  disease  was  transmitted  by  mosquitoes.  In  Africa  some  savage 
tribes  call  malaria  the  "mosquito  disease."  In  1848  Nott,  of  jSTew  Or- 
leans, considered  the  matter  proven  from  biological  analogies.  In  1882 
King,  of  Washington,  vigorously  advocated  the  mosquito  theory  based 
upon  philosophical  deductions  but  no  proof.  In  1884  Laveran  suggested 
mosquito  transmission  as  probable.  In  1894  Manson  elaborated  the 
mosquito  theory  and  inspired  Eoss,  of  the  Indian  Army  Medical  Service, 
who  in  1895  demonstrated  that  the  crescents  of  estivoautumnal  malaria 
underwent  changes  in  the  mosquito.  In  1896  Bignami  advocated  the 
theory  and  compared  it  to  the  transmission  of  Texas  fever  by  the  tick. 
In  1897  Eoss  published  further  convincing  observations  upon  the  de- 
velopment of  the  estivoautumnal  parasite  in  the  mosquito.  In  1898  Mc- 
CoUum  observed  an  important  missing  link  in  the  life  cycle  by  observ- 
ing the  flagellum  of  the  microgametocyte  (male)  fertilize  the  macro- 
gametocyte  (female)  with  the  formation  of  the  vermicule.  These  ob- 
servations were  made  upon  Halteridum  or  malaria  of  birds ;  later  he  saw 
the  same  phenomenon  in  estivoautumnal  malaria.  The  life  cycle  of  the 
malarial  parasite  has  been  confirmed  by  Daniels,  Koch,  Grassi,  Big- 
nami, Celli,  Manneberg,  Schaudinn,  and  many  others. 

Further  evidence  that  malaria  is  transmitted  by  the  mosquito  was 
furnished  by  Sambon  and  Low,  of  the  London  School  of  Tropical  Medi- 
cine, and  Dr.  Terzi,  who  lived  during  the  three  most  malarial  months  of 
1900  in  Ostia,  a  very  malarial  locality  of  the  Eoman  Campagna.  These 
observers  escaped  infection  simply  by  keeping  within  their  well-screened 
huts  from  before  sundown  until  after  sunrise.  The  final  proof  was  fur- 
nished in  1900  by  Dr.  P.  Thurber  Manson  and  Mr.  George  Warren,  who 
were  bitten  by  infected  mosquitoes  forwarded  from  Italy  in  cages  to 
London. 

The  Malarial  Mosquito.— At  least  twenty-five  species,  in  six  genera 
of  the  subfamily  Anophelinae  are  more  or  less  definitely  known  to  carry 
malaria.^     In  Europe  Anopheles  maculipennis;  in  tropical  America  A. 

^The  subfamily  Anophelinae  has  been  divided  by  Theobald  (1901)  into  sev- 
eral genera:  Anopheles,  Myzomyia,  Cellia,  Myzorhynchus,  Nyssorhyncus,  Py- 
retophorus,  etc. 

^See  Craig,  The  Malarial  Fevers,  New  York,  1909,  and  Knab,  Am.  Jour,  of 
Tropical  Diseases  and  Preventive  Medicine,  July,  1913,  I,  1,  p.  37,  also  Castellani 
and  Chalmers,  Manual  of  Tropical  Medicine,  1913,  for  full  list,  classification  and 
geographical  distribution. 


230 


INSECT-BORNE    DISEASES 


argyrotarsus  or  albipes;  in  temperate  America,  A.  quadrimaculatus 
which  is  probably  the  same  as  A.  maculipennis ;  in  India  A.  sin&nsis;  in 
Africa  A.  costalis  are  the  chief  culprits.  Darling^  found  that  70.8  per 
cent,  of  Anopheles  albimanus  induced  to  bite  malarial  patients  became 
infective,  while  with  Anopheles  pseudo  pun  clip  ennis  only  12.9  per  cent, 
could  be  infected. 

The  Anopheles  mosquitoes  are  brownish  and  rather  large.  They  may 
be  distinguished  by  the  fact  that  the  palpi  in  both  the  male  and  the 
female  are  at  least  as  long  as  the  proboscis.  Only  the  female  transmits 
the  infection.  It  sits  more  or  less  at  right  angles  upon  the  wall,  the 
head,  thorax,  and  abdomen  being  in  a  straight  line.     Contrary  to  the 

yellow  fever  mosquito,  the  mala- 
rial mosquito  is  nocturnal  in  its 
habits  and  breeds  chiefly  in  the 
open  ponds,  puddles,  and  natural 
collections  of  water  in  the  woods, 
fields  and  swamps. 

The  mosquito  becomes  infect- 
ed upon  drinking  the  blood  con- 
taining the  micro-  and  macroga- 
metocytes.  It  requires  about 
twelve  days  before  the  sporozo- 
ites  appear  in  the  salivary  glands 
of  the  insect.  It  cannot,  there- 
fore, transmit  the  infection  to  an- 
other person  until  the  lapse  of 
this  extrinsic  period  of  incuba- 
tion. The  infected  mosquito  may 
live  a  long  time  and  infect  more 
than  one  person  successively.  The  malarial  parasite  seems  to  be  a  harm- 
less saprophyte  for  the  mosquito. 

The  parasite  will  not  develop  in  the  mosquito  when  the  mean  tem- 
perature is  below  60°  F. 

None  of  the  Anophelinae  are  "domestic"  in  the  sense  of  our  house 
mosquitoes,  such  as  Culex  pipicus,  C.  quinquefasciatus  and  Aedes  calopus, 
and  this  is  not  necessary  for  the  transmission  of  malaria.  The  long 
presence  of  the  malarial  parasite  in  the  human  circulation,  and  the  conse- 
quent frequent  opportunity  for  the  mosquito  to  acquire  the  infection 
from  carriers  compensates  for  a  much  looser  association. 

Practically  all  the  species  of  Anopheles  are  blood  feeders,  but  they 
have  the  appetite  for  blood  developed  to  different  degrees. 

Immunity. — A  person  who  once  has  had  malaria  is  more  apt  to  have 

^  Darling,  Samuel  T.  Transmission  of  Malarial  Fever  in  the  Canal  Zone  by 
Anopheles  Mosquitoes.     Jour.  A.  M.  A.,  1909,  LIII,  pp.  2051-2053. 


Fig.  21. — Anopheles  Punctipennis. 


MOSQUITOES  231 

subsequent  attacks.  Ordinarily  there  is  an  increased  susceptibility  rather 
than  an  immunity.  However,  repeated  infections,  especially  during  early 
life,  leave  a  very  pronounced  resistance.  In  malarious  regions  many  chil- 
dren carry  the  parasites  in  their  circulating  blood  without  any  manifesta- 
tions of  the  disease.  These  carriers  are  important  factors  in  spreading 
the  infection  in  endemic  areas,  and  must  be  taken  into  account  in  pre- 
ventive measures. 

There  is  no  true  racial  immunity  in  this  disease.  Occasionally  a  con- 
genital immunity  seems  to  be  transmitted;  this  must  be  rare.  Prac- 
tically all  persons  who  receive  the  infection  for  the  first  time  are  sus- 
ceptible. The  freedom  from  malaria  which  some  persons  seem  to  enjoy 
may  be  accounted  for  partly  by  the  fact  that  mosquitoes  seldom  bite 
such  persons.  It  is  well  known  that  on  account  of  the  odors,  or  what 
not,  mosquitoes  do  not  bother  certain  individuals.  No  doubt  the  infec- 
tion of  a  small  number  of  parasites  is  often  overcome  largely  through 
a  vigorous  phagocytosis. 

Individual  resistance  varies  in  different  individuals  and  in  the  same 
individual  at  different  times.  The  parasite  may  remain  latent  in  the 
spleen  and  other  organs  for  years.  Exposure,  overeating,  fasting,  over- 
work, or  worry,  or  anything  that  lowers  the  vitality  of  such  individuals 
predisposes  to  an  attack  of  malaria.  The  disease  often  breaks  out  in 
persons  in  good  health  leaving  a  malarial  region  for  a  health  resort, 
whether  mountain  or  seashore.  I  was  enabled  to  confirm  this  observa- 
tion upon  the  returning  transports  from  Cuba  following  the  Spanish- 
American  war,  when  many  cases  of  malaria  broke  out  among  the  troops 
previously  in  good  health  upon  reaching  the  cold  winds  about  Cape 
Hatteras.  Personal  prophylaxis,  therefore,  involves  careful  attention  to 
personal  hygiene. 

Prevention. — The  successful  suppression  of  malaria  requires  a  com- 
bined attack  upon  the  mosquito  and  the  parasite  in  the  human  host. 
Ultimate  success  rests  upon  the  suppression  of  the  mosquito.  This, 
however,  is  a  difficult  and  expensive  undertaking  in  the  case  of  Anophe- 
linae.  Immediate  relief  is  most  quickly  gained  by  measures  directed 
against  the  infection  in  man.  Screening  and  quinin  prophylaxis,  while 
practical,  are  only  temporary  measures. 

Celli  ^  found  that  although  the  destruction  of  mosquitoes  is  possible 
in  the  laboratory  and  in  small  areas,  the  difficulties  in  extensive  areas 
are  generally  insuperable. 

Harris  maintains  that  the  most  practical  measure  at  this  time  in  the 
crusade  against  malaria  is  the  radical  cure  of  those  harboring  parasites. 
Every  person  cured  means  one  less  focus  of  infection.  Koch  and  Celli, 
in  1900,  urged  that  the  best  way  of  dealing  with  malaria  in  the  island  of 

^  Celli:  Cited  by  Leslie:  Proc.  of  the  Imperial  Malarial  Conf.,  Simla,  India, 
1910,  p.  8. 


232  INSECT-BOKNE    DISEASES 

Mauritius  would  be  to  leave  the  mosquito  alone  and  to  cure  the  human 
patients  from  whom  the  insects  become  infected.  By  the  use  of  this 
method  Eoss  tells  us  that  Stephensport  in  New  Guinea  was  cleared  of 
malaria  in  a  few  months. 

Le  Prince  ^  demonstrated  that  in  some  sections,  at  least,  anopheles 
will  fly  great  distances.  There  is,  however,  very  little  doubt  that  in 
the  majority  of  places  malaria  is  a  local  infection ;  that  is,  the  mosquitoes 
acquire  the  gametes  and  transmit  the  sporozoites  within  a  restricted  area. 

The  maximum  malarial  rate  is  at  its  height  at  or  toward  the  end  of 
the  warm  season,  because  warmth  over  60°  F.  favors  the  development 
of  the  parasite  within  the  mosquito.  The  best  time  to  attack  the  parasites 
in  man  is  during  the  winter  and  early  spring  so  as  to  prevent  infection 
of  the  new  summer  brood  of  mosquitoes. 

Measures  Directed  Against  the  Mosquito. — If  the  breeding  of 
Anophelinae  mosquito  could  be  stopped  malaria  would  cease.  Mosquito 
suppression  is  fundamental  and  radical.  The  best  way  to  abolish  the 
breeding  places  of  malaria  mosquitoes  is  to  fill  up  low  places  or  to  dry 
the  surface  of  the  land  with  drains.  These  two  measures  hold  first 
place  as  permanent  work.  The  underdraining  of  large  areas  of  our 
arable  land  of  the  Middle  West  with  tiled  drain  has  been  very  effective 
in  suppressing  malaria.  Open  ditches  properly  constructed  and  cared 
for  are  likewise  effective.  In  the  tropics  the  ditches  should  be  lined 
with  cement,  on  account  of  the  luxuriant  vegetation  which  soon  interferes 
with  their  efficiency  or  may  actually  convert  them  into  breeding  places. 
The  open  ditches  are  much  the  cheapest  in  first  cost,  but  not  when 
maintenance  is  reckoned.  The  draining  of  swamp  lands  is  an  engineer- 
ing problem  in  which  the  economic  factor  looms  large.  One  of  the  very 
best  means  of  destroying  the  breeding  places  of  the  malaria  mosquito 
is  to  clear  the  land  and  to  keep  it  under  cultivation. 

"When  drainage  is  not  practical,  the  number  of  mosquitoes  may  be 
kept  down  by  introducing  fish  into  the  pools,  streams,  ditches,  and  other 
collections  of  water.  Upon  limited  water  surfaces  the  larvae  may  be 
killed  with  a  film  of  coal  oil  or  the  Panama  larvicide  (page  225). 

Large  open  spaces  cause  the  destruction  of  a  number  of  mosquitoes, 
as  they  cannot  live  long  in  the  hot  sun;  therefore,  clearing  the  brush 
and  high  grass,  which  furnish  shelter  to  the  insects,  aids  in  preventing 
wild  mosquitoes  approaching  dwelling  houses. 

The  use  of  screens  and  culicides  has  already  been  referred  to. 

Personal  Prophylaxis. — Persons  visiting  or  residing  in  a  malari- 
ous region  should  be  particularly  careful  not  to  expose  themselves  at 
night  time.     The  experience  of  Sambon  and  Low  on  the  Eoman  Cam- 

*Le  Prince:  "Recent  Progress  in  Antimalaria  Work,  with  Special  Eeference 
to  Anopheles  Flight  as  Studied  on  the  Isthmus  of  Panama."  Tr.  Fifteenth  In- 
ternat.  Cong,  on  Hyg.  and  Demog.,  V,  Part  II,  p.  544. 


MOSQUITOES  233 

pagna  is  instructive  and  should  be  imitated.  The  location  of  the  resi- 
dence is  important.  In  a  city  it  should  be  a  reasonably  safe  distance 
from  the  native  quarter,  because  the  infection  is  there  most  concentrated. 
The  dwelling  should,  if  possible,  face  the  trade  winds.  A  row  of  tall 
trees  will  partly  screen  the  house  from  the  swamp,  but  the  trees  must 
not  be  too  close,  else  they  will  furnish  shelter  for  the  insects.  The 
house  should  be  on  high  land  if  practicable,  as  it  is  an  old  observation 
that  the  malarial  mosquito  does  not  fly  high.  People  living  upon  the 
second  floor  are  less  apt  to  contract  the  infection  than  those  who  sleep 
on  the  ground  floor.  If  it  is  necessary  to  go  out  in  the  night  time,  one 
may  protect  himself  by  the  use  of  gloves  and  mosquito  netting  hang- 
ing from  the  helmet  to  the  shoulders.  Care  must  be  taken  to  guard 
the  ankles  against  mosquito  bites.  As  all  these  measures  require  much 
time  and  attention  to  details,  they  are  usually  not  efficient  in  actual 
practice.     Therefore,  quinin  prophylaxis  is  much  used. 

QuiNiN  Prophylaxis. — Theoretically  the  administration  of  quinin 
to  healthy  individuals  for  the  prevention  of  malaria  is  not  an  ideal 
method  of  prophylaxis,  for  it  does  not  prevent  infection,  but  only  destroys 
the  parasites  in  the  blood  during  the  period  of  incubation ;  practically  it 
is  cheap  and  effective.  It  should  be  remembered  that  quinin  kills  only 
the  young  and  tender  forms  of  the  plasmodium,  and  has  no  influence 
upon  the  crescents.  Quinin  prophylaxis  is  indicated  in  proportion  to  the 
difficulty  of  pursuing  more  permanent  methods.  It  is  especially  valuable 
where  screens  and  mosquito  bars  are  not  available,  as  in  camping,  march- 
ing, traveling,  or  where  the  occupation  takes  one  out  at  night.  When 
residents  of  non-malarial  countries  go  into  malarial  localities,  especially 
in  the  rural  districts,  for  short  periods  of  time,  quinin  is  a  valuable 
preventive. 

A  farmer  may  not  be  able  to  drain  and  clear  his  land  so  as  to  get 
rid  of  mosquitoes;  he  may  not  be  able  to  screen  his  house  and  keep  his 
screens  in  order,  but  he  will  always  be  able  to  buy  the  amount  of  quinin 
which  will  protect  his  family  from  fever,  especially  as  it  may  cost  no 
more  to  prevent  malaria  than  it  would  to  cure  it — maybe  less.  Quinin 
prophylaxis  is  not  so  good  a  method  as  suppressing  mosquitoes,  but  in 
many  communities  this  is  impracticable;  it  is  not  so  good  as  screening, 
carefully  watched,  but  this  is  also  impracticable  in  many  rural  com- 
munities. 

The  systematic  use  of  quinin  as  a  prophylactic  on  a  large  scale  is 
of  recent  origin.  The  government  of  Italy  in  1902  began  the  sale  of 
quinin  at  cost  price  to  communities  and  towns,  which  agreed  to  distribute 
it  gratuitously  to  those  unable  to  purchase  it.  In  1903  the  towns,  etc., 
were  obligated  to  issue  it  free  of  cost  to  poor  people  for  prophylactic 
use.  The  next  year,  1904,  it  was  ordered  to  be  given  to  all  working 
people  for  use  in  this  way.     This  is  a  beneficent  public  health  measure 


^34  INSECT-BOENE    DISEASES 

comparable  to  the  free  distribution  of  antitoxin  and  vaccin  virus.  There 
has  been  a  great  diminution  in  the  amount  of  malaria  among  the  farm- 
ing people  of  Italy  since  the  introduction  of  quinin  prophylaxis;  further- 
more, the  reduction  has  been  progressive — increasing  as  the  people  learn 
its  value. 

To  be  effective  as  a  preventive  of  malaria,  quinin  must  be  taken  in 
sufficient  doses  during  the  entire  malarial  season.  The  size  of  the  dose 
and  the  interval  at  which  the  prophylactic  is  administered  are  of  the 
utmost  importance.  There  are  two  principal  methods  of  administration ; 
the  one  canonized  by  Koch  consists  of  large  doses  at  considerable  inter- 
vals; the  other,  used  in  Italy,  consists  of  smaller  daily  amounts.  Koch 
advised  16  grains  (one  gram)  of  quinin  every  sixth  or  seventh  day,  or 
every  seventh  or  eighth  day,  eighth  or  ninth,  ninth  or  tenth  day,  ac- 
cording to  the  danger  of  the  infection.  This  manifestly  leaves  several 
intervening  days  in  which  there  is  no  quinin  in  the  circulation.  The 
method  has  been  eminently  successful  in  the  very  malarious  districts 
of  German  West  Africa,  and  also  in  the  hands  of  the  Japanese  in  For- 
mosa. There  are  several  modifications  of  Koch's  method.  Plehn  advises 
8  grains  every  five  days;  this  amount  may  even  be  taken  twice  a  week. 

Ziemann  gives  a  gram  of  quinin  sulphate  every  four  days.  The  al- 
kaloid is  administered  in  solution  with  5  drops  of  hydrochloric  acid  early 
in  the  morning  or  about  one  and  one-half  to  two  hours  after  a  meal. 
A  convenient  rule  is  to  give  a  dose  on  the  first  of  the  month  and  there- 
after on  each  day  of  the  month  divisible  by  4.  By  this  method  the  alka- 
loid is  probably  constantly  in  the  circulating  blood. 

The  administration  of  small  doses  of  quinin  daily  is  the  oldest  method 
of  giving  quinin  as  a  prophylactic.  The  amount  varies  from  II/2  to  7 
grains  daily.  In  Italy  the  average  amount  is  5  to  7  grains  of  sulphate 
of  quinin  daily,  and  half  that  amount  for  children  under  10  years.  For 
children  the  tannate  of  quinin  made  up  into  chocolates  is  recommended. 
The  tannate  of  quinin  contains  only  about  half  the  amount  of  quinin 
found  in  the  sulphate,  therefore  about  5  grains  of  the  tannate  is  the 
equivalent  of  2I/2  grains  of  the  sulphate. 

On  the  Isthmus  of  Panama  good  results  have  been  obtained  by  the 
use  of  moderate  doses,  3  to  6  grains  per  day.  When  the  disease  increases 
in  prevalence  or  virulence  the  amount  is  raised  to  8  or  10  grains  per 
day,  then  dropping  off  to  4  or  5.  Craig  found  2%  grains  of  quinin 
per  day  sufficient  against  tertian  and  quartan  infections. 

The  particular  method  of  election  in  giving  quinin  prophylaxis 
should  be  chosen  according  to  the  experience  of  the  region.  Whatever 
method  of  quinin  prophylaxis  is  selected  the  quinin  should  be  taken 
throughout  the  malarial  season,  say  June  to  November.  Those  who  have 
had  malaria  should  begin  in  ^larch  or  April  in  order  to  prevent  relapses, 
for  latent  malaria  is  very  apt  to  reassert  itself  in  the  spring. 


MOSQUITOES  335 

It  is  advisable  not  to  stop  the  use  of  quinin  immediately  on  the 
advent  of  cold  weather  or  on  leaving  a  malarial  district,  even  if  one  has 
not  had  malarial  fever.  It  is  good  practice  to  continue  the  quinin  for 
one  or  two  months,  until  natural  resistance  can  overcome  the  infec- 
tion. 

No  ill  effects  have  been  noted  from  the  prolonged  use  of  quinin  as 
advised  above.  Carter  ^  states  that  many  Americans  at  Panama,  where 
the  malarial  season  lasts  12  months,  took  three  2-grain  tablets  of  quinin 
daily  for  2^^  years  without  complaint  or  injury.  The  quinin  was  passed 
around  at  the  mess  tables  at  Ancon  Hospital  as  regularly  as  the 
biscuits. 

Occasionally  an  individual  is  found  who  has  an  idiosyncrasy  to 
quinin.  Some  people  bear  quinin  less  well  than  others.  Five  to  7  grains 
may  cause  discomfort  at  first,  but  a  tolerance  may  be  established  by 
persevering  a  week  or  two. 

Quinin  taken  as  a  prophylactic  does  not  develop  ''blackwater  fever" — 
on  the  contrary,  by  diminishing  the  number  and  severity  of  the  malarial 
attacks,  it  diminishes  the  liability  to  hemorrhagic  malarial  fever. 

Quinin  prophylaxis  lowers  the  malarial  sick-rate  and  death-rate. 
Celli's  statistics  for  Italy  are  convincing.  Good  results  are  also  reported 
from  Greece,  Algeria  and  Panama.  The  deaths  from  malaria  in  Italy 
during  10  years  preceding  1902  averaged  14,048  annually,  whereas  dur- 
ing the  nine  years  following  1902  the  average  fell  to  3,853  per  year  as 
a  result  of  quinin  prophylaxis.  Better  results  were  obtained  when  quinin 
prophylaxis  was  compulsory  as  in  the  penal  agricultural  colony  at  Castia- 
das,  where  the  malaria  was  reduced  from  76  per  cent,  of  the  force  to 
5  per  cent.  The  results  in  the  Italian  Army  were  equally  good.  When 
the  quinin  was  taken  under  orders  malarial  fever  fell  from  27.5  per 
cent,  in  1902  to  4.9  per  cent.,  of  which  3  per  cent,  were  relapses,  in 
1911. 

The  way  quinin  prevents  the  development  of  malaria  is  almost  cer- 
tainly by  keeping  the  number  of  parasites  below  the  number  necessary 
to  produce  an  attack.  It  does  not  prevent  the  development  of  "carriers," 
yet  it  lessens  the  amount  of  malaria  by  diminishing  the  number  of  para- 
sites. As  malaria  lessens,  prosperity  increases  from  the  improvement  in 
strength  and  energy  of  the  people,  and  with  increased  prosperity  comes 
land  better  cleared  and  better  drained,  houses  screened,  and  better  hygiene 
generally — an  endless  chain  of  betterment.  It  is  only  in  this  way — by 
quinin  prophylaxis  leading  to  antimosquito  work — that  permanent  re- 
sults can  be  obtained. 

Quinin  prophylaxis  has  advantages  that  commend  it  as  a  prompt, 
cheap  and  practical  measure.  It  is  at  best,  however,  only  tentative,  and 
does  not  take  the  place  of  mosquito  suppression. 

ip.  H.  Reports,  Mar.  28,  1914,  Vol.  29,  No.  13,  p.  741. 


236  mSECT-BOENE    DISEASES 

REFERENCES 

Deadrick:     "A  Practical  Study  of  Malaria."    Philadelphia,  1909. 

Craig :    "The  Malarial  Fevers,  Hemoglobinuric  Fever  and  the  Blood  Proto- 
zoa of  Man."    New  York,  1909. 

Hanson :    "Malaria  Etiology,  Pathology,  Diagnosis,  Prophylaxis  and  Treat- 
ment."    St.  Louis,  1913. 

Ross :     "The  Prevention  of  Malaria."     London,  1910. 

The   original   discovery    of   the   malarial   parasite   was    announced   by 

Laveran  in  the  Acad,  de  Med.,  Paris,  Nov.  23,  1880,  and  Dec.  28,  1880. 


YELLOW  FEVER 

The  prevention  of  yellow  fever  rests  entirely  upon  the  fact  that  it 
is  communicated  through  the  bite  of  an  infected  mosquito — the  Stego- 
myia  calopus}  The  mosquito  becomes  infected  by  sucking  the  blood  of 
yellow  fever  patients  during  the  first  three  days  of  the  fever.  All  the 
experimental  evidence  thus  far  shows  that  the  infection  is  absent  from 
the  blood  after  the  third  day,  and  that  mosquitoes  do  not  become  in- 
fective after  this  period.  The  importance  of  this  fact  in  preventing  the 
spread  of  the  disease  is  evident.  The  mosquito,  after  drinking  the  in- 
fected blood,  is  not  able  to  transfer  the  infection  to  another  person  until 
about  twelve  days  ^  have  elapsed ;  that  is,  it  requires  about  twelve  days 
for  the  yellow  fever  parasite,  whatever  it  may  be,  to  undergo  its  cycle 
of  development  in  the  mosquito.  The  mosquito  once  infected  remains 
so  during  the  rest  of  its  life,  which  may  be  many  months.  Only  the 
female  mosquito  transmits  the  infection;  the  male  Stegomyia  calopus  is 
a  vegetarian;  its  proboscis  is  too  soft  to  penetrate  the  skin.  A  single 
sting  of  a  single  infected  mosquito  is  sufficient  to  produce  the  disease. 
An  infected  mosquito  may  infect  more  than  one  person  at  different 
times. 

The  prevention  and  control  of  yellow  fever  are  based  upon  a  series 
of  epoch-making  investigations  and  discoveries  (1900-1902)  by  a  com- 
mission composed  of  Walter  Eeed,  James  Carroll,  Aristides  Agramonte, 
and  Jesse  W.  Lazear,  medical  officers  of  the  United  States  army.  These 
experiments  have  been  fully  confirmed,  and  in  some  respects  amplified, 
by  independent  workers,  namely,  Guiteras  of  Cuba  (1901)  ;  Barreto,  de 
Barros,  and  Eodrigues,  of  Brazil  (1903)  ;  Eoss  (1902) ;  Parker,  Beyer, 
and  Pothier  (1903)  ;  Eosenau,  Parker,  Francis,  and  Beyer  (1901) ;  Eose- 

^This  mosquito  was  first  called  Culeoo  fasciatus,  which  was  changed  to 
Stegomyia  fasciatus,  and  then  to  Stegomyia  calopus,  and  recently  expressed  as 
Aedes  calopus  by  Coquillett. 

.^This  constitutes  the  extrinsic  period  of  incubation,  in  contradistinction  to 
the  intrinsic  period  of  incubation,  that  is,  the  time  between  the  mosquito  bite 
and  the  onset  of  symptoms,  whicli  is  from  2  to  5  and  sometimes  6  days  in  this 
disease. 


MOSQUITOES  337 

nau  and  Goldberger  (1906),  of  America;  Marchoux,  Salimbeni,  and 
Simond  (1903);  Marchoux  and  Simond  (1906)^  of  France;  and  Otto 
and  jSTeumann  (1905),  of  Germany. 

The  cause  of  yellow  fever  is  unknown.  The  virus  is  ultramicroscopic, 
that  is,  passes  the  close-grained  pores  of  the  finest  porcelain  filter. 
While  in  nature  the  disease  is  transmitted  only  through  the  bite  of  an 
infected  Stegomyia,  the  disease  may  be  transferred  experimentally  by 
taking  some  of  the  blood  from  a  patient  during  the  first  three  days  of 
the  fever  and  injecting  it  into  a  susceptible  individual.  So  far  as  is 
known,  yellow  fever  is  peculiar  to  man,  for  all  other  animals  tested  have 
failed  to  react.  At  one  time  it  was  generally  believed  that  yellow  fever 
infection  was  conveyed  by  fomites.  This  has  been  disproved,  and  we  now 
know  that  there  is  no  danger  from  soiled  clothing  or  other  inanimate 
things,  even  though  stained  with  the  black  vomit  and  other  dis- 
charges. 

The  diagnosis  of  yellow  fever  rests  upon  clinical  evidence  and  is  fre- 
quently difficult  to  make,  especially  in  the  early  stages.  It  is,  therefore, 
important  to  screen  all  cases  of  fever  in  a  yellow  fever  campaign  until 
the  nature  of  the  illness  is  established. 

Immunity. — There  is  no  natural  immunity  to  yellow  fever.  All  per- 
sons receiving  the  infection  for  the  first  time  seem  to  be  susceptible. 
Contrary  to  the  usual  statement,  there  is  no  racial  immunity  in  this  dis- 
ease, for  negroes,  Chinese,  Indians,  and  other  races  take  the  disease.  One 
attack  of  yellow  fever  afi^ords  protection  against  a  subsequent  attack. 
The  acquired  immunity  in  this  disease  is  one  of  the  strongest  known 
and  lasts  throughout  the  lifetime  of  the  individual.  Two  attacks  of  yel- 
low fever  are  almost  unknown.  I  reported  a  supposed  instance  in  a 
Spaniard  in  Havana,  but  the  diagnosis  of  the  first  attack  was  not  con- 
clusive. 

In  endemic  areas  children  may  have  yellow  fever,  which  leaves  them 
immune  for  life.  The  disease  often  runs  a  mild  and  unrecognized  course 
in  children,  and  this  fact  explains  the  supposed  natural  immunity  of 
natives  in  endemic  foci. 

The  Yellow  Fever  Mosquito. — The  yellow  fever  mosquito  has  a  wide 
distribution  ranging  from  38  degrees  south  to  38  degrees  north  latitude. 
They  are  found  in  the  East  and  West  Indies,  China,  Sumatra,  Java, 
India,  Philippine  Islands,  Japan,  Hawaiian  Islands,  in  the  southern  part 
of  Italy,  Africa,  Spain,  South  America,  etc.  They  usually  prefer  the 
lowlands.  I  have  found  them  as  far  up  the  mountains  as  Orizaba  in 
Mexico,  4,200  feet  above  sea  level.  In  the  United  States  they  are  very 
prevalent  south  of  the  Potomac  along  the  gulf  coast,  but  are  absent  or 
rare  in  the  higher  elevations  of  Georgia  or  Alabama,  which  are,  there- 
fore, non-infectable  regions. 

The  yellow  fever  mosquito  is  a  domestic  insect.     It  breeds  by  pref- 


238 


INSECT-BOENE    DISEASES 


erence  in  any  standing  water  about  the  household,  such  as  cisterns,  rain 
barrels,  or  any  collection  of  water  in  buckets,  bottles,  old  cans,  etc.  The 
yellow  fever  mosquito  does  not  breed  in  the  fields,  woods,  and  swamps, 
which  are  the  favorite  resorts  of  the  malarial  mosquito.  The  Stegomyia 
mosquitoes  do  not  fly  far  of  their  own  volition,  but  show  a  cat-like  ten- 
dency to  remain  about  their  place  of  birth  or  adoption.     All  these  facts 

have  an  evident  bearing 
upon  preventive  meas- 
ures. A  thorough  knowl- 
edge of  the  biology  of  the 
mosquito  is  essential  to 
the  success  of  a  yellow 
fever  campaign. 

It  is  important  to  re- 
member that  the  yellow 
fever  mosquito  is  chiefly 
active  during  the  day 
time.  It  cannot,  how- 
ever, distinguish  between 
artificial  light  and  sun- 
light. I  have  watched 
Stegomyia  mosqu  i  t  o  e  s 
bite  me  by  electric  light 
at  eleven  o'clock  at  night. 
Its  attack  is  often  noise- 
less and  its  bite  painless. 
However,  as  a  rule,  they 
rest  at  night,  which, 
therefore,  diminishes  the 
risk  of  exposure  at  that 
time.  The  Stegomyia 
mosquito,  however,  can- 
not survive  for  long  in 
the  direct  rays  of  a  tropi- 
cal sun.  There  is,  therefore,  little  danger  in  visiting  a  community  where 
yellow  fever  is  epidemic  during  the  day  time,  provided  the  person  keeps 
out  of  houses.  The  experiences  during  the  last  yellow  fever  epidemic 
at  New  Orleans,  1905,  showed  that  the  radius  of  activity  of  an  infected 
Stegomyia  is  contracted.  It  may  possibly  at  times  fly  across  the  street, 
but  it  is  evident  that  it  neither  flies  far  nor  is  it  ordinarily  transported 
to  any  great  distance  on  railroad  cars,  although  it  may  be  carried  over 
seas  on  ships. 

The  yellow  fever  mosquito  may  pass  a  screen  composed  of  16  strands 
or  15  meshes  to  the  inch,  but  cannot  pass  one  containing  20  meshes  or 


Fig.  22. — Stegomyia  Calopus  (female). 


MOSQUITOES 


239 


19  strands  to  the  inch.     Effective  screens  must,  therefore,  be  at  least 
this  fine. 

Stegomyia  calopus  is  a  grayish  mosquito  of  average  size  with  beauti- 
ful glistening  silver-white  markings.  These  markings  are  lyre-shaped 
on  the  back  of  the  thorax ;  silver-white  spots  are  seen  on  the  side  of  the 
thorax.  White  lines  are  apparent  at  each  tarsal  joint  and  also  on  the 
palpi ;  the  scutellum  is  white.  In  the  female  the  palpi  are  much  shorter 
than  the  proboscis,  which  at  once  distinguishes  it  from  Anopheles. 

Egg. — The  female  lays  her  eggs  on  the  surface  of  the  water  or  just 
above  the  water  line.  The  eggs  do  not  adhere  to  one  another,  and  hence 
do  not  form  the  compact  boat-shaped  mass  characteristic  of  the  culex, 
but  float  on  their  sides  more  or  less  singly.  At  the  moment  of  laying 
the  eggs  are  a  cream  color, 
but  rapidly  become  jet  black. 
They  are  somewhat  cigar- 
shaped,  and  measure  on  the 
average  about  0.55  mm.  in 
length  and  0.16  mm.  in  width 
at  the  broadest  part.  The  eggs 
show  marked  powers  of  resist- 
ance to  unfavorable  influences. 
They  may  be  kept  dry  for  six 
and  one-half  months,  and  still' 
retain  their  vitality,  and  hatch 
out  when  put  back  into  the 
water.  Freezing  does  not  kill 
them.  The  egg  probably  plays 
an  important  role  in  the  hi- 
bernation of  the  yellow  fever 
mosquito.  The  winged  insect  may  also  survive  a  short  winter.  Under 
the  most  favorable  conditions  as  to  temperature  (30°  C.)  Stegomyia 
eggs  hatch  out  in  about  36  hours  after  they  are  laid.  Under  20°  C. 
they  will  not  hatch  at  all. 

Laeva. — The  egg  hatches  the  larva  ("wiggle-tail"),  which  has  a 
black  barrel-shaped  respiratory  siphon.  This  distinguishes  it  from  Culex 
pipiens,  its  common  mess  mate,  in  which  the  air  tube  is  brown,  longer, 
and  more  slender.  Although  the  larva  lives  in  the  water,  it  is  strictly 
an  air-breather  and  must  come  to  the  surface  for  air.  It  thrusts  its 
breathing  tube  up  into  the  surface  film  and  remains  suspended,  head 
down,  at  an  angle  of  somewhat  less  than  45  degrees,  which  distinguishes 
it  from  Anopheles  larvae,  which  lie  horizontal.  A  film  of  oil  on  the 
surface  of  the  water  is  sufficient  to  obstruct  the  air  tube  and  thus  cause 
the  death  of  the  larva  by  suffocation.  The  larva  is  very  timid,  so  that 
a  slight  jar  or  agitation  or  a  sudden  shadow  will  cause  it  to  wriggle 


Fig.  23. — Head  of  Stegomyia  Calopus  (male). 


240 


INSECT-BOENE    DISEASES 


rapidly  to  the  bottom,  where,  indeed,  it  may  very  commonly  be  observed 
to  feed.     The  duration  of  the  larval  sta^e  is  never  less  than  G  to  7 


Fig.  24. — Eggs  of  Stegomyia  Calopus. 


days,  and  depends  upon  the  food  supply  and  temperature.  Under  certain 
conditions  it  may  be  prolonged  for  weeks.  Freezing  for  short  periods 
does  not  appear  to  injure  it. 

Pupa. — The  larva  changes  into  the  pupa.    The  pupa  is  not  provided 


Fig.  25. — Larva  of  Stegomyia  Calopus. 
Respiratory  Syphon  of  Culex  to  the  Right. 


MOSQUITOES 


241 


with  a  mouth  and  does  not  feed.  It  is  an  air-breather  and  spends  most 
of  its  time  at  the  surface  of  the  water.  The  pupal  stage  lasts  at  least 
36  hours,  during  which  time  metamorphosis  occurs  into  the  imago  or 
perfect  winged  insect. 

Imago. — Under  the  most  favorable  conditions  it  is  at  least  9  days 
from  the  time  the  Stegomyia  lays  its  egg  to  the  appearance  of  the 
imago.  Under  natural  conditions  the  length  of  life  of  the  adult  female 
probably  varies  greatly.  Guiteras  succeeded  in  keeping  a  presumably 
infected  one  alive  for  154  days  during  the  fall  and  winter  temperature 


Fig.  26. — Pupa  of  Stegomtia  Calopus. 


in  Havana.  Deprived  of  water,  it  does  not  usually  survive  longer  than 
3%  to  4  days,  and  only  very  exceptionally  5  days.  This  fact  has  a 
bearing  on  the  possibility  of  transporting  the  mosquito  in  band-boxes, 
trunks,  and  other  containers. 

"Aerial"  Conveyance. — It  is  notorious  that  yellow  fever  is  usually 
conveyed  but  a  short  distance  "aerially" — perhaps  across  the  street,  or, 
more  often,  to  a  neighboring  house  in  the  rear.  This  represents  a  dis- 
tance of  some  75  yards,  which  is  about  as  far  as  we  may  expect  it  to 
be  thus  conveyed,  from  our  knowledge  of  the  habits  and  flight  of  the 
Stegomyia  mosquito.  The  longest  distance  recorded  in  recent  years  of 
aerial  conveyance  is  one  of  225  meters  (Melier)  and  one  of  456  feet 
(Carter).  These  are  entirely  exceptional.  My  experience  in  the  deten- 
tion of  hundreds  of  susceptible  immigrants  in  quarantine  for  days  in 
Havana  harbor  showed  that  infected  Stegomyiae  do  not  travel  a  short 


343  INSECT-BORNE    DISEASES 

distance  across  the  water.  This  observation  is  in  confirmation  of  others, 
that  vessels  moored  within  1,200  feet  off  the  shore  are  entirely  safe  so 
far  as  yellow  fever  is  concerned,  provided,  of  course,  personal  intercourse 
is  interdicted  or  supervised. 

Prevention. — The  prevention  or  suppression  of  yellow  fever  may  be 
attacked  in  either  one  of  its  two  hosts,  man  or  insect.  If  every  person 
developing  yellow  fever  were  immediately  isolated  from  the  Stegomyia 
mosquito,  the  disease  would  inevitably  cease.  The  elimination  of  the 
Stegomyia  mosquito  would  give  the  same  happy  result.  Usually  both 
methods  of  attack  are  employed.  It  would  seem  easier  to  control  the 
human  host  simply  by  screening  during  the  first  three  or  four  days 
of  the  fever.  Practically  this  method  has  been  found  insufficient,  be- 
cause the  disease  is  difficult  to  diagnose  in  the  early  stage,  and  the 
mild  cases  escape  attention.  The  essence  of  yellow  fever  prevention, 
therefore,  consists  in:  (1)  screening  cases  of  yellow  fever  and  all  sus- 
pected cases  of  yellow  fever;  (2)  destruction  of  infected  insects;  (3) 
the  suppression  of  Stegomyiae  through  the  control  of  their  breeding 
places.  It  was  a  combination  of  these  three  methods  which  was  first  so 
brilliantly  carried  out  by  Gorgas  in  Havana  in  1901,  and  later  in 
Panama;  by  White  in  New  Orleans,  1905;  by  Liceaga  for  Vera  Cruz, 
and  recently  by  Oswaldo  Cruz  in  Eio  de  Janeiro,  1909. 

Yellow  fever  patients  should  be  isolated  only  in  the  sense  of  separat- 
ing them  from  Stegomyia  calopus.  This  may  be  done  by  proper  screen- 
ing. It  is  not  necessary  to  remove  the  patient  to  a  hospital,  although 
this  is  desirable,  for  the  reason  that  a  special  hospital  is  more  carefully 
guarded  than  is  practicable  in  a  private  house,  and  the  trained  assistants 
are  an  additionl  safeguard.  As  soon  as  the  patient  is  removed,  the 
mosquitoes  in  the  house  and  the  surrounding  houses  should  at  once  be 
destroyed.  Yellow  fever  patients  must  be  moved  with  caution,  for  the 
reason  that  undue  excitement  or  exertion  seems  to  increase  the  severity 
of  the  disease. 

The  insecticides  best  suited  for  the  destruction  of  mosquitoes  are : 
sulphur  dioxid,  hydrocyanic  acid  gas,  pyrethrum  powder,  tobacco  smoke, 
Mim's  culicide  (camphor  and  phenol)  (see  page  214).  At  first  glance 
it  might  appear  to  be  a  hopeless  task  to  attempt  to  eradicate  the  yel- 
low fever  mosquito  in  a  large  city,  but  that  this  is  possible  was  demon- 
strated in  New  Orleans  in  1905,  when,  after  several  months  of  a  vigorous 
campaign,  it  was  difficult  to  find  a  Stegomyia  mosquito.  The  measures 
consisted  mainly  in  screening  the  water  cisterns  and  eliminating  all 
standing  collections  of  water  in  and  about  the  household. 

Histoirical  Note, — Dr.  Charles  J.  Finlay  studied  the  relation  of  the 
mosquito  to  yellow  fever  as  far  back  as  1883  and  1883.  The  first  in- 
sects used  by  the  United  States  Army  Commission  to  bring  about  the 
demonstration  of  the  new  doctrine  were  received  from  the  hands  of  Dr. 


MOSQUITOES  343 

Finlay.  Finlay  believed  that  the  cause  of  the  disease  was  a  micrococcus 
and  considered  that  the  insects  were  capable  of  transmitting  the  infection 
a  few  days  after  they  had  stimg  a  yellow  fever  patient.  Sternberg's 
studies  upon  yellow  fever  are  published  by  the  Government  as  a  report 
of  the  United  States  Marine  Hospital  Service  on  the  Etiology  and 
Prevention  of  Yellow  Fever,  1890.  Carter's  observations  at  Orville, 
Mississippi,  upon  the  extrinsic  period  of  incubation  were  published  in 
the  Medical  Record,  June  15,  1901. 

The  work  of  the  United  States  Army  Commission  appeared  in  the 
following  publications : 

"The  Etiology  of  Yellow  Fever — a  Preliminary  Note,"  Proceedings 
of  the  28th  Annual  Meeting  of  the  x\m.  Pub.  Health  Assn.,  Oct.  22-26, 
1900;  also  Philadelphia  Med.  Jour.,  Oct.  27,  1900. 

"The  Etiology  of  Yellow  Fever— An  Additional  Note,"  J.  A.  M.  A., 
Feb.  16,  1901. 

"Experimental  Yellow  Fever,"  Am.  Med.  Jour.,  July  6,  1901. 

"Etiology  of  Yellow  Fever — Supplemental  Note,"  Am.  Med.  Jour., 
Feb.  22,  1902. 

On  account  of  their  historical  interest  and  accuracy,  the  conclusions 
of  the  United  States  Army  Commission  are  here  given: 

1.  The  mosquito — C.  fasciatus — serves  as  the  intermediate  host 
for  the  parasite  of  yellow  fever. 

2.  Yellow  fever  is  transmitted  to  the  non-immune  individual  by 
means  of  the  bite  of  the  mosquito  that  has  previously  fed  on  the  blood 
of  those  sick  with  this  disease. 

3.  An  interval  of  about  12  days  or  more  after  contamination  ap- 
pears to  be  necessary  before  the  mosquito  is  capable  of  conveying  the 
infection. 

4.  The  bite  of  the  mosquito  at  an  earlier  period  after  contamina- 
tion does  not  appear  to  confer  any  immunity  against  a  subsequent  at- 
tack. 

5.  Yellow  fever  can  also  be  experimentally  produced  by  the  sub- 
cutaneous injection  of  blood  taken  from  the  general  circulation  during 
the  first  and  second  days  of  the  disease. 

6.  An  attack  of  yellow  fever  produced  by  the  bite  of  the  mosquito 
confers  immunity  against  the  subsequent  injection  of  the  blood  of  an 
individual  suffering  from  the  non-experimental  form  of  this  disease. 

7.  The  period  of  incubation  in  thirteen  cases  of  experimental  yel- 
low fever  has  varied  from  forty-one  hours  to  five  days  and  seventeen 
hours. 

8.  Yellow  fever  is  not  conveyed  by  fomites,  and  hence  disinfection 
of  articles  of  clothing,  bedding,  or  merchandise,  supposedly  contami- 
nated by  contact  with  those  sick  with  this  disease,  is  unnecessary. 

9.  A  house  may  be  said  to  be  infected  with  yellow  fever  only  when 


244  INSECT-BOENE    DISEASES 

there  are  present  within  its  walls  contaminated  mosquitoes  capable  of 
conveying  the  parasite  of  this  disease. 

10.  The  spread  of  the  yellow  fever  can  be  most  effectually  con- 
trolled by  measures  directed  to  the  destruction  of  mosquitoes  and  the 
protection  of  the  sick  against  the  bites  of  these  insects. 

11.  While  the  mode  of  propagation  of  yellow  fever  has  now  been 
definitely  determined,  the  specific  cause  of  this  disease  remains  to  be 
discovered. 

Prevention  of  Malaria  and  Yellow  Fever  Contrasted. — For  the  pre- 
vention of  malaria  the  same  principles  guide  us  that  have  been  set 
forth  for  the  prevention  of  yellow  fever.  In  practical  application,  how- 
ever, our  methods  of  attack  differ,  owing  to  differences  in  the  habits  of 
the  two  mosquitoes,  and  owing  to  differences  in  the  two  diseases.  The 
malarial  problem  is  much  more  difficult,  because  it  is  harder  to  get  rid 
of  Anopheles  than  of  Stegomyia.  The  breeding  places  of  the  yellow 
fever  mosquito  are  practically  confined  to  artificial  containers  in  the 
neighborhood  of  human  habitations,  while  those  of  Anopheles  are  found 
in  marshes,  pools,  or  streams,  and  often  in  collections  of  water  in  the 
grass  or  brush.  The  breeding  places  of  the  malarial  mosquito  cover  a 
much  larger  area,  frequently  the  whole  country,  and  are  rather  hard 
to  find  and  difficult  to  destroy;  also  this  insect  travels  much  further 
from  its  breeding  place  than  the  Stegomyia.  Compared  to  yellow  fever, 
the  control  of  the  malarial  human  host  presents  special  difficulties.  In 
yellow  fever  man  is  infective  to  the  Stegomyia  only  three  days ;  in  malaria 
the  parasites  continue  in  the  circulating  blood  a  very  long  time.  In  the 
case  of  malaria,  then,  we  have  to  deal  with  chronic  carriers,  which,  for- 
tunately for  us,  does  not  occur  in  yellow  fever.  For  malaria  we  have 
quinin  as  a  prophylactic,  whereas  no  known  drug  will  prevent  yellow 
fever. 

DENGUE 

All  who  visit  the  tropics  or  subtropical  countries  where  dengue  pre- 
vails are  very  apt  sooner  or  later  to  contract  this  infection.  So  far  as 
known,  few  persons  have  ever  died  of  dengue.  Although  the  mortality 
is  practically  nil,  the  disease  is  a  painful  affection  and  sometimes  leaves 
the  body  in  a  weakened  condition  for  long  periods  of  time.  In  its 
epidemiology  and  symptomatology  the  disease  strikingly  parallels  yellow 
fever,  which  adds  to  its  importance.  Outbreaks  of  dengue  often  precede 
and  may  be  coincident  with  those  of  yellow  fever.  In  the  tropics  influ- 
enza and  dengue  are  also  frequently  confused.  Dengue  also  has  some 
resemblance  to  the  three-day  fever  or  pappataci  fever  of  Herzegovina, 
which  is  transmitted  by  the  bite  of  the  Phlehotomus  pappatasii,  a  biting 

There  is  no  definite  immunity  produced  by  an  attack  of  dengue. 


MOSQUITOES  345 

Persons  often  give  a  history  of  an  attack  in  each  outbreak.     The  cause 
of  the  disease  is  not  known. 

Graham  studied  dengue  in  Beirut,  Syria,  and  described  a  protozoon 
inhabiting  the  red  blood  corpuscles  and  closely  resembling  the  Plasmo- 
dium of  malaria  except  for  the  absence  of  pigment.^  Graham  believed 
that  this  organism  underwent  a  developmental  stage  within  the  mos- 
quito (Culex  fatigans).  He  claimed  to  have  observed  the  spores  of  this 
organism  "in  among  the  cells  of  the  salivary  glands"  after  48  hours  in 
mosquitoes  which  had  bitten  a  dengue  patient  upon  the  fourth  day  of 
the  disease.  Graham  produced  a  very  severe  case  of  fever  resembling 
dengue  by  inoculating  a  man  subcutaneously  with  peptonized  normal 
salt  solution  containing  the  salivary  glands  of  a  mosquito  which  had 
.bitten  a  dengue  patient  24  hours  before.  Graham's  observations  con- 
cerning the  parasite  in  the  blood  and  in  the  mosquito  have  not  been 
confirmed,  although  the  subject  has  been  studied  by  several  experienced 
microscopists.  Carpenter  and  Sutton,^  however,  obtained  two  positive 
results  out  of  four  experimental  cases  of  mosquito  inoculation.  The 
period  of  incubation  in  one  of  these,  however,  was  two  weeks,  and  the 
subjects  were  not  sufficiently  controlled  to  exclude  the  bites  of  other  mos- 
quitoes. Agramonte  ^  studied  an  epidemic  in  Habana  which  was  ac- 
companied by  a  plague  of  Culex  fatigans.  He  attempted  to  transmit 
the  disease  by  mosquitoes,  trying  various  species  at  various  intervals 
after  the  insects  had  fed  upon  dengue  patients,  but  did  not  succeed  in 
producing  the  disease  in  this  way.  Guiteras  and  Finlay  *  endeavored 
to  transmit  the  disease  with  Culex  piniens,  but  with  negative  results. 
Guiteras,  Finlay,  Agramonte,  and  others  who  have  worked  upon  this 
subject  state  that  their  faith  remains  unshaken  that  the  mosquito  acts 
as  the  vector  of  dengue,  despite  the  negative  results  of  their  experi- 
ments. 

Ashburn  and  Craig  ^  in  1907  studied  the  disease  in  Manila  and 
showed  that  the  virus  is  contained  in  the  blood  during  the  febrile  stage. 
The  intravenous  inoculation  of  filtered  dengue  blood  into  healthy  men 
is  followed  by  a  typical  attack  of  the  disease.  The  cause  of  the  disease 
is,  therefore,  probably  ultramicroscopic.  They  transmitted  the  infec- 
tion by  the  mosquito,  Culex  fatigans,  and  concluded  that  this  is  probably 
the  most  common  method  of  transmission.  The  period  of  incubation  in 
the  experimental  cases  averaged  3  days  and  14  hours.  They  concluded 
from  their  studies  that  dengue  is  "not  a  contagious  disease,  and  is 
infectious  in  the  same  manner  as  are  yellow  fever  and  malaria."  At 
times  dengue  appears  to  be  one  of  the  most  communicable  of  all  diseases, 

Vow.  Trop.  Med.,  1903,  Vol.  VI,  p.  209. 

''Jour.  A.  M.  A.,  1905,  XLIV. 

^'New  York  Med.  Jour.,  1906,  LXXXIV, 

*Rev.  Med.  Trop.,  1906,  Vol.  VII,  p.  53. 

^Philippine  Jour,  of  8ci.,  Vol.  II,  No.  2,  Section  B,  May  1,  1907. 


246  INSECT-BORNE    DISEASES 

for  it  spreads  like  wildfire  and  spares  practically  no  one  in  the  com- 
munity. 

All  our  preventive  measures  are  novi^  based  upon  the  supposition  that 
dengue  is  a  mosquito-borne  infection.  An  instance  showing  the  non- 
contagiousness  of  dengue  is  given  by  Persons,  U.  S.  N. :  A  squad  of 
marines  from  the  U.  S.  S.  Baltimore  were  given  shore  leave  at  Cavite. 
Twenty  of  the  24  marines  who  had  been  ashore  came  down  with  the 
disease  after  returning  to  the  ship,  while  there  was  a  totcl  absence  of 
infection  among  those  who  had  remained  aboard.  Observations  made 
at  the  Naval  Hospital  at  Canacao  demonstrated  that  in  the  mosquito- 
free  wards  the  disease  did  not  spread,  M^hereas  when  the  hospital  was 
located  at  Cavite  it  was  noted  that  practically  every  case  admitted 
became  infected  with  dengue  while  under  treatment  for  the  original  com- 
plaint (Stitt). 

FILARIASI8 

The  filaria  is  a  long,  slender  filiform  threadworm  with  a  curved  or 
spiral  tail.  The  adult  worms  live  in  the  connective  tissue,  lymphatics, 
and  body  cavities.  The  embryos  or  larvae  are  found  in  great  numbers 
in  the  blood.  In  several  species  of  which  the  life  history  is  known  mos- 
quitoes act  as  the  intermediate  host.  The  most  important  filariae  of  man 
are:  (1)  Filaria  hancrofti,  the  larva  of  which  is  known  as  Filaria 
nocturna,  appearing  in  the  blood  at  night  and  occurring  in  all  tropical 
lands,  including  America;  (2)  Filaria  loa,  the  larva  of  which  is  known 
as  Filaria  diurna  occurring  in  the  blood  by  day  and  prevalent  in  West 
Africa  and  India;  (3)  the  Filaria  perstans,  the  larva  of  which  is  known 
as  Filaria  perstans,  which  persists  in  the  blood  both  day  and  night,  and 
occurs  especially  in  West  Africa  and  a  number  of  other  places.  None  of 
these  young  worms  do  any  appreciable  injury  in  the  blood;  of  the  adult 
worms,  only  one,  namely,  Filaria  lancrofti,  can  be  viewed  as  serious, 
causing  elephantiasis,  while  the  second  species,  Filaria  loa  is  more  or  less 
troublesome.  According  to  Manson,  we  are  hardly  justified  at  present  in 
assuming  that  all  the  other  species  are  entirely  without  effect  upon  their 
hosts.  These  parasites  infect  man  throughout  the  tropical  and  sub- 
tropical belt.  In  the  United  States  the  infection,  while  not  very  preva- 
lent, is  endemic  as  far  north  as  Charleston. 

According  to  Manson,  Culex  jatigans,  and  according  to  James  the 
Anopheles  nigerrinus,  are  the  intermediate  hosts.  When  fed  on  the 
blood  of  a  filarial-infested  individual,  it  is  found  that  the  filarial  larvae 
soon  escape  from  their  sheaths  in  the  thickened  blood  within  the  stomach 
of  the  mosquito.  They  pierce  the  stomach  wall,  enter  the  thoracic  mus- 
cles of  the  insect,  pass  through  a  metamorphosis  which  takes  from  16 
to  20  days  (longer  or  shorter,  according  to  atmospheric  temperature) ; 
they  now  quit  the  thorax  and  a  few  find  their  way  to  the  abdomen;  the 


FLIES 


247 


vast  majority,  however,  pass  forward  through  the  prothorax  and  neck, 
and,  entering  the  head,  coil  themselves  up  close  to  the  base  of  the  pro- 
boscis and  beneath  the  pharynx  and  under  surface  of  the  cephalic  ganglia. 
This  account  is  taken  from  Manson,  to  whose  personal  interest  in  this 
disease  we  are  indebted  for  the  advances  in  our  knowledge  of  the  entire 
subject  of  filariasis.  The  wonderful  preparations  of  Low  may  be  seen 
at  the  London  School  of  Tropical  Medicine,  showing  the  Filaria  nocturna 
in  the  head  and  proboscis  of  the  mosquito  ready  to  come  out  when  the 
proboscis  of  the  insect  pierces  its  victim.  The  fact  that  the  mosquito  is 
the  intermediate  host  in  conveying  the  infection  of  Filaria  rests  upon 
these  observations  and  not  upon  experiments  which  demonstrate  the 
actual  transference  of  the  disease.  Whether  the  worm  may  obtain  an 
entrance  by  any  other  channel  or  medium  would,  according  to  Manson, 
be  hard  to  prove  and  rash  to  deny.  Our  correct  preventive  measures  are 
based  upon  the  theory  that  this  is  an  insect-borne  disease,  although  other 
possible  modes  of  transference  must  not  be  neglected.-  Prophylaxis, 
therefore,  depends  upon  the  suppression  of  the  mosquito  and  the  pre- 
vention of  the  infective  mosquito-bite.  As  it  is  not  definitely  known 
how  many  species  of  mosquitoes  convey  the  infection,  the  preventive 
measures  must  be  along  general  lines;  a  combination  of  those  described 
under  malaria  and  yellow  fever,  as  well  as  general  sanitation  and  per- 
sonal hygiene. 

FLIES 


The  true  flies  have  but  two  wings,  that  is,  they  belong  to  the  order 
Diptera.  They  comprise  an  enormous  number  of  species.  Contrary  to 
popular  opinion,  flies  are  poor  scavengers.  Most  flies  prefer  the  sun- 
shine, but  species  vary  greatly 
in  their  habits  and  breeding 
places.  However,  surprisingly 
little  is  known  of  the  life  his- 
tory and  habits  of  most  flies. 
The  subject  lacks  attraction — 
especially  the  maggots  or  larval 
stage.  The  life  history  of  the 
house  fly  in  general  was,  down 
to  1873,  mentioned  in  only 
three  European  works,  and  few 
exact  facts  were  given.  Dr.  A. 
S.    Packard,    then    of    Salem, 

Mass.,  studied  the  house  fly  and  gave  descriptions  of  all  its  stages, 
showing  that  the  growth  of  a  generation  from  the  egg  to  the  adult 
occupies  from  10  to  14  days.     In  1895  Howard  further  traced  the  life 


Fig.  27. — House  Fly  (Musca  domestica) , 
Showing  Proboscis  in  the  Act  of 
Eating  Sugar. 


348 


INSECT-BOENE    DISEASES 


history  and  indicated  that  120  eggs  are  laid  by  a  single  female,  and 
that  a  generation  is  produced  every  10  days  at  the  summer  tempera- 
tures of  Washington.  There  may  be,  therefore,  12  generations  in  a 
summer.  If  each  female  lays  only  120  eggs  (1,000  have  been  noted), 
we  have  the   possibility   of   countless   millions   coming  from   a  single 

fly  during  a  single  sea- 
son. Allowing  2,880  flies 
to  the  ounce,  it  has  been 
estimated  that  the  total 
product  of  a  single  fly  in 
40  days  would  equal  810 
pounds,  provided  only 
one-half  of  them  sur- 
vived; hence,  the  logical 
time  to  begin  fly  sup- 
pression is  in  the  early 
spring.  Flies  transmit  disease  in  one  of  several  ways.  The  biting  flies, 
such  as  the  tsetse  flies,  which  transmit  sleeping  sickness,  inoculate  the 
trypanosome  directly  into  the  system  by  piercing  the  skin  with  their 
mouth  parts.  The  common  house  fly  does  not  bite.  Biting  flies,  such 
as  the  Stomoxys  calcitrans,  abound  in  the  United  States  in  stables, 
houses,  and  also  in  nature.     They  have  recently  been  implicated  as 


Fig.  28. — Eggs  of  House  Fly  as  Laid  in  a  Mass. 


Fig.  29. — Eggs  of  House  Fly.     Some  have  hatched. 


go-betweens  in  poliomyelitis,  and  also  in  anthrax,  relapsing  fever,  horse 
sickness  (Pferdesterbe),  and  epithelioma  of  fowls.  Other  blood-sucking 
genera,  such  as  Tabanus,  Clirysops,  Haematohia,  etc.,  are  of  common 
occurrence,  but  are  not  known  to  carry  any  infection  regularly. 


FLIES 


249 


The  following  brief  account  of  the  common  house  fly  may  be  taken 
as  a  type  of  the  life  history  and  habits  of  flies  in  general.  Eemedies 
and  preventive  measures  depend  upon  the  peculiarities  in  the  life  his- 
tory and  habits  of  each  particular  genus  and  species. 

Life  History  of  the  Musca  Domestica. — A  few  adults  live  over  the 
winter  in  cellars,  barns,  attics,  and  out-of-the-way  places,  and  as  soon 
as  warm  weather  sets  in  they  lay  their  eggs  in  manure  or  organic 
refuse.  In  6  to  8  hours  the  eggs  hatch  into  larvae  (maggots),  which 
grow  rapidly  and  are  fully  developed  in  4  or  5  days.  Each  larva  then 
becomes  a  pupa  in  a  hard  brown  case — the  puparium.  In  5  days  more 
the  pupal  case  opens  and  the  adult  fly  appears  for  a  season  of  activity 
covering  several  weeks.    Most  of  them  die  in  the  early  autumn,  in  great 


Fig.  30. — Larvae  of  House  Fly. 


part  due  to  a  fungus  disease,  caused  by  Empusa  muscae  which  becomes 
prevalent  among  the  flies  at  this  season  of  the  year.  A  few  are  left  and 
hibernate  to  continue  the  species.  Hence,  it  takes  about  10  days  from 
egg  to  imago.  It  is,  therefore,  important  to  remove  manure,  garbage, 
and  other  organic  refuse  at  least  as  often  as  this  in  order  to  prevent 
the  development  of  the  winged  insects. 

The  chief  breeding  place  of  common  house  flies  is  in  horse  manure. 
They  also  have  been  found  to  breed  in  human  excrement,  fermenting 
vegetable  and  putrefying  animal  matter,  in  the  bedding  in  poultry  pens, 
in  refuse  hog  hair,  in  tallow  vats,  in  carcasses  of  various  animals,  and  in 
garbage  and  organic  material  of  all  kinds.  All  of  which  means  that  if 
we  allow  the  accumulation  of  filth  we  will  have  house  flies. 

The  larvae  of  house  flies  have  a  tendency  to  crawl  away  from  their 
breeding  places ;  many  of  them  burrow  into  the  loose  ground  just  beneath 
the  manure  piles,  or  crawl  under  boards  or  stones,  or  into  dry  manure 
collected  under  platforms  or  the  like.  This  tendency  of  migrating  ap- 
pears three  or  four  days  before  pupating.     The  larvae  leave  the  moist 


250 


INSECT-BOKNE    DISEASES 


manure  for  a  dry,  dark  place.  This  migrating  habit  is  of  great  advan- 
tage in  that  the  winged  fly,  at  the  time  of  emergence,  is  thus  afforded 
an  easy  path  to  freedom.  Advantage  may  be  taken  of  this  migrating 
habit  to  trap  many  larvae.     They  should  be  driven  out  of  the  manure 

pile  by  moistening  it  and 
trapped  in  a  basket  or  box,  or 
drowned  in  water. 

Life  History  of  Stomoxys 
Calcitrans. —  Stromoxys  ccdci- 
trans,  the  biting  stable  fly,  is 
very  similar  to  the  house  fly 
in  its  life  history  and  in  ap- 
pearance during  the  pre- 
paratory stages,  but  devel- 
ops more  slowly,  requiring 
nearly  a  month  to  undergo  a 
complete  life  cycle.  The  eggs 
are  laid  like  those  of  the 
house  fly  in  horse  manure,  but 
more  frequently  in  ferment- 
ing heaps  of  grass,  cow-dung, 
The  adult  flies  are  much  like  the 
They  feed  exclu- 


FiG.  31. — PuPAHiuM  OF  House  Fly. 


brewer's  refuse  ("spent  hops"),  etc 
house  fly,  but  have  a  sharp,  needle-like  proboscis, 
sively  on  mammalian  blood  and  are  a  great  annoyance  to  horses  and 
cattle  in  late  summer  and  autumn.  They  bite  persons  less  frequently, 
but  are  of  importance  on 
account  of  their  possible 
relation  to  poliomyelitis, 
anthrax,  etc.  The  sta- 
ble fly  can  best  be  con- 
trolled by  eliminating  its 
breeding  places. 

Flies    as    Mechanical 
Carriers   of   Infection. — 
Leidy  in  1864  attributed 
the   spread   of   gangrene 
in   hospitals   during   the 
Civil  War  to  the  agency 
of  the  house  fly.     Short- 
ly thereafter  it  was  dis- 
covered that  the  bite  of  the  gad-fly  may  transmit  anthrax  from  cattle 
to  man.    Later  it  was  found  that  purulent  ophthalmia  of  the  Egyptians 
is  carried  by  the  house  fly,  and  the  spread  of  an  infectious  conjunctivitis 
known  as  "pink  eye"  in  the  South  has  been  shown  by  Hubbard  to  be 


Fig.  32. — Stable  FhY  (Stomoxys  calcitrans) .     (Brues.) 


FLIES 


251 


Fig.  33.— Head  Show- 
ing Proboscis,  Stom- 
oxYS  Calcitrans. 
(Brues.) 


facilitated  by  little  midges  of  the  genus  Hippelates.  Reference  has 
already  been  made  to  the  bite  of  the  tsetse  flies  in  spreading  nagana, 
sleeping  sickness,  and  other  t'rypanosomatic  infections.  Recently  the 
stable  fly  has  been  shown  to  be  able  to  transmit  various  infections  in  a 
mechanical  way. 

It  is  now  known  that  typhoid  fever  and  other  intestinal  infections 
may  be  transmitted  by  the  common  house  fly.     Celli  in  1888  fed  flies 

with  pure   cultures  of  typhoid,  tuberculosis   and 

anthrax,  and  showed  that  the  virulent  bacilli  were 
passed  in  the  dejecta.  Kober  in  1892  was  one  of 
the  first  to  call  special  attention  to  the  danger  of 
contaminating  food  supplies  by  flies  coming  from 
the  excreta  of  typhoid  patients.  The  United  States 
Army  Commission — Eeed,  Vaughan,  and  Shake- 
speare— studied  the  presence  of  typhoid  fever  in 
our  camps  during  the  Spanish-American  war  in 
the  summer  of  1898.  They  concluded  that  flies 
undoubtedly  serve  as  carriers  of  the  infection. 
"Flies  swarm  over  infected  fecal  matter  in  the  pits 

and  then  deposit  it  and  feed  upon  the  food  prepared  for  the  soldiers  at 
the  mess  tents.  In  some  instances,  where  lime  had  recently  been  sprinkled 
over  the  contents  of  the  pits,  flies  with  their  feet  whitened  with  lime  were 
,  seen  walking  over  the  food."  Vaughan  subsequently  stated  that  he  con- 
sidered that  about  15  per  cent,  of  the  cases  of  typhoid  in  the  camps  were 
caused  by  fly  transmission. 

Alice  Hamilton  ^  isolated  typhoid  bacilli  from  5  out  of  18  house  flies 

captured  in  Chicago  in 
the  privies  and  fence  near 
a  sick  room.  It  has  been 
shown  experimentally 
that  living  typhoid  bacilli 
may  remain  in  or  upon 
the  bodies  of  flies  for  as 
long  as  33  days  after  in- 
fection. 

Howard    studied    fly 
abundance  in  relation  to 
the  origin  and  prevalence  of  typhoid  fever  in  the  District  of  Columbia 
in  the  summer  of  1908.^     No  particular  correlation  between  the  preva- 
lence of  the  flies  and  the  prevalence  of  the  disease  could  be  made  out. 
Flies  undoubtedly  spread  the  infection  of  typhoid  fever,  but  the  im- 

^Jour.  A.  M.  A.,  1903,  40,  p.  .576. 

='Rosenau,  Lumsden.  ar-d  Kastle:     Report  No.  3,  1908,  P.  H.  and  M.  H.  S., 
Hygienic  Laboratory  BvJl.  .A"o.  52. 


Fig.  34. — Wing  of  Stable  Fly  {Stomoxys  calcitrans). 


252 


INSECT-BORNE    DISEASES 


portance  of  the  role  they  play  in  this  regard  varies  considerably  with 
circumstances.  In  camps,  unsewered  towns,  and  overcrowded  places  in 
poor  sanitary  condition  the  danger  from  flies  may  be  considerable,  but 
even  under  the  worst  conditions  it  is  doubtful  whether  flies  ever  play 
the  major  role  or  are  responsible  for  the  bulk  of  typhoid  fever,  as  has 
been  stated.  In  a  well-sewered  city,  such  as  Washington,  we  concluded 
that  the  flies  are  probably  responsible  but  for  an  occasional  case  of  the 
disease.  It  is  very  difficult  in  any  particular  instance  to  know  quantita- 
tively just  how  much  of  the  infection  is  conveyed  by  flies  and  how  much 
by  contacts.  The  danger  of  flies  is  great  enough  without  the  need  of 
exaggeration,  and  their  suppression  fully  justifies  the  best  energies  of 
the  health  officer.  It  is  perhaps  a  mistake  to  call  the  common  house 
fly  the  "typhoid  fly,"  not  alone  for  the  reason  that  the  disease  is  spread 

in  many  other  ways,  but 
for  the  reason  that  the 
fly  is  responsible  for  the 
spread  of  many  infec- 
tions other  than  typhoid 
fever.  Flies  undoubtedly 
play  the  same  role  in  dys- 
entery, cholera,  and  all 
other  intestinal  infec- 
tions that  they  do  in 
typhoid  fever.  Tizzoni 
and  Cattani  in  1896  dem- 
onstrated active  cholera 
organisms  in  the  dejecta 
of  flies  caught  in  the  cholera  colonies  of  Bologna,  Italy.  These  observa- 
tions were  subsequently  verified  and  extended  by  Simonds,  Offelman, 
McRae,  and  others. 

It  is  now  quite  evident  that  flies  lighting  upon  a  case  of  smallpox, 
measles,  scarlet  fever,  and  other  exanthematous  disease  may  very  readily 
transmit  these  infections  to  another  person.  I  have  actually  seen  mag- 
gots breeding  in  the  open  lesions  of  a  case  of  smallpox  treated  in  the 
open  air  at  Eagle  Pass,  Texas. 

Flies  may,  in  the  same  mechanical  way,  transmit  the  infection  of 
erysipelas,  anthrax,  glanders,  and  other  skin  infections.  It  is  known 
that  flies  may  ingest  tuberculous  sputum  and  excrete  tubercle  bacilli 
which  may  remain  virulent  as  long  as  15  days.  Flies  have  also  been 
associated  with  leprosy  and  many  other  diseases. 

Esten  and  Mason  ^  counted  the  bacterial  population  of  415  flies  and 
found  that  the  number  of  bacteria  on  a  single  fly  may  range  all  the 
way  from  550  to  6,600,000.     Early  in  the  fly  season  the  numbers  of 
'^Store's  Agricultural  Experiment  Station,  Bull.  No.  51,  April,  1908. 


Fig.  35. — The    "Little    House    Fly"    {Homalomyia 
canicularis   $).     (Hewitt.) 


FLIES 


253 


bacteria  on  flies  are  comparatively  small,  while  later  the  numbers  are 
very  large.  The  places  where  flies  live  also  determine  largely  the  num- 
ber of  bacteria  they  carry.  The  average  of  the  415  flies  was  about  one 
and  one-quarter  million  bacteria.  The  method  of  the  experiment  was 
to  introduce  the  flies  into  a  sterile  bottle  and  pour  into  the  bottle  a 
known  quantity  of  sterilized  water,  then  shake  the  bottle  to  wash  the 
bacteria  from  the  body  of  the  fly.  The  numbers,  therefore,  only  repre- 
sent those  carried  on  the  outside  and  not  those  in  the  intestinal  tract. 
The  experiments  of  Esten  and  Mason  were  designed  to  stimulate  the 
number  of  microorganisms  that  would  come  from  a  fly  in  falling  into 
milk. 

Torrey  ^  found  that  a  single  fly  may  carry  from  570  to  4,400,000 
bacteria  upon  its  surface,  and  from  16,000  to  28,000,000  in  its  intes- 
tinal tract.     The  prevailing  types  are  Streptococcus  equinus  fecalis  and 


Fig.  36. — Wing  of  House  Fly,  Showing  How  It  Carries  Dust  Particles. 

salivarius,  which  are  also  found  in  the  breeding  and  feeding  places  of 
the  house  fly.  Torrey  also  obtained  three  cultures  of  B.  paratypJiosus 
which  is  especially  significant. 

Even  though  flies  breed  in  manure,  and  the  larvae  teem  with  bacteria, 
the  adult  winged  insect,  when  newly  hatched,  contains  fewer  micro- 
organisms. This  cleansing  is  due  to  the  active  phagocytosis  which  takes 
place  during  metamorphosis  from  pupa  to  imago.  The  bacteria  in  the 
intestinal  tract  of  the  newly  hatched  imago  are  mostly  extruded  soon  after 
emergence  from  the  puparium. 

Bacot,^  however,  has  shown  that  certain  species  of  bacilli  ingested 
during  the  larval  period  of  Musca  domestica  can  retain  their  existence 
while  their  host  is  undergoing  the  process  of  metamorphosis,  and  continue 
their  existence  in  the  gut  of  the  adult  fly,  but  that  their  number  dimin- 
ishes suddenly  after  emergence.  In  a  subsequent  work  Bacot  ^  demon- 
strated that  Bacillus  pyocyaneus  may  thus  survive.     Faichnie,* 

V.  A.  M.  A.,  May  11,  1912,  LVIII,  No.  19,  p.  1445. 
''Trans.  Ento.  Soc,  London,  1911,  Part  II,  p.  497. 
^Parasitology,  IV,  I,  Mar.,  1911,  p.   68. 
*Jour.  Roy.  Army  Med.  Corps,  XIII,  1909. 


254  INSECT-BOENE    DISEASES 

how  B.  iypkoHUs  may  also  persist.  Lediii^^liain  coiifirnis  these  con- 
clusions, and  states  that  he  has  recently  isolated  li.  lijplioKus  from  pupa, 
the  larvae  of  which  have  fed  on  this  organism. 

Graham- Smith  ^  recovered  B.  anthracis  from  blow  flics  bred  from 
larvae  fed  on  meat  infected  with  the  organism,  but  failed  to  recover 
B.  typhosus  and  B.  enteritidis. 

Among  the  list  of  diseases  of  which  there  is  more  or  less  evidence 
that  the  infection  may  be  conveyed  by  flies  are :  typhoid,  cholera,  dysen- 
tery, diarrhea  in  infants,  anthrax,  yaws,  erysipelas,  ophthalmia,  diph- 
theria, smallpox,  plague,  tropical  sore,  parasitic  worms,  sleeping  sick- 
ness, poliomyelitis,  relapsing  fever,  and  several  infections  of  the  lower 
animals. 

An  interesting  light  was  thrown  on  the  possible  modes  of  dissemina- 
tion of  the  eggs  and  larvae  of  hookworms  by  Galli-Valerio  (1905).  He 
placed  eggs  and  larvae  of  Ankylostoma  duodenalis  in  a  bottle  with  flies, 
and  on  washing  found  many  eggs  and  encapsulated  larvae  which  had 
adhered  to  their  bodies,  but  none  in  the  flies'  intestines. 

Flies  may  transmit  the  virus  of  disease  mechanically,  either  through 
their  dejecta  or  upon  their  mouth  parts,  legs,  and  other  surfaces  of  the 
body.  The  flies  may  carry  the  infection  directly  to  our  lips  or  indirectly 
to  our  food  or  to  any  surface  upon  which  they  light. 

English  observers  prove  that  house  flies  may  come  a  mile  from  an 
infected  dump  to  the  nearest  village.  Hodge,^  investigating  the  abun- 
dance of  flies  on  the  cribs  in  Lake  Erie  off  Cleveland,  came  to  the  con- 
clusion that  flies  are  blown  at  least  six  miles  off  shore,  and  that  they 
gather  on  the  cribs  as  temporary  resting  places. 

The  maximum  flight  in  the  experiments  made  at  Cambridge,  Eng- 
land, was  770  yards  across  open  fenland.^  Their  dispersal  is  favored 
by  fine  weather  and  warm  temperature.  They  will  even  go  against  or 
across  the  wind,  attracted  perhaps  by  the  odors  it  may  convey.  Flies  do 
not  travel  as  far  in  towns  as  in  open  country,  probably  on  account  of 
food  and  shelter  afforded  by  the  houses. 

Suppression. — The  suppression  of  the  common  house  fly  may  be  ac- 
complished by  striking  at  their  breeding  places.  In  a  city  this  does  not 
present  very  great  difficulty.  It  resolves  itself  simply  into  a  matter  of 
cleanliness — organic  cleanliness  of  our  environment.  The  chief  breed- 
ing places  are  in  horse  manure  and  garbage-  These  should  be  given 
first  attention.  One  neglected  stable  will  furnish  a  plague  of  flies  for 
an  entire  neighborhood.  Their  suppression  in  a  well  ordered  city  for- 
tunately is  neither  expensive  nor  difficult,  but  it  requires  a  well-trained 

^Eepts.  to  Local  Gov.  Bd.,  New  Series,  No.  .53,  1911. 
'Hodge,  C.  F.:      Science,   1913,  XXXVIII,  512. 

^  Local  Gov.  Board  on  Public  Health  Subjects,  1913,  N.  S.  No.  85,  pp.  20-41, 
by  Hindley  and  Merriman,  also  Jour.  Hyg.,  1914,  XIV,  23. 


FLIES 


255 


and  capable  corps  of  inspectors  with  sufficient  authority  to  enforce  the 
regulations.  The  suppression  of  flies  by  voluntary  effort  through  the 
slow  process  of  education  cannot  be  relied  upon. 

In  cities,  stable  manure  should  be  placed  in  properly  covered  recep- 
tacles and  removed  at  least  once  a  week.  This  one  measure  obviates  the 
use  of  borax,  kerosene,  chlorid  of  lime,  Paris  green,  or  arsenate  of  lead,  all 
of  which  are  expensive  and  uncertain  unless  used  frequently  and  in  liberal 
amounts;  further,  they  decrease  the  fertilizing  value  of  the  manure. 

Garbage  should  be  kept  in  water-tight  cans  with  good  covers  and 
removed  frequently,  especially  in  the  warm  weather.  Eefuse  on  city 
lots,  in  back  yards,  in  alleys,  about 
wharves,  markets,  and  similar  places 
should  be  regularly  taken  away. 
Householders,  provision  merchants, 
storekeepers,  and  others  should  be 
held  responsible  for  the  cleanliness 
and  tidiness  of  their  premises,  and 
those  who  violate  these  simple 
and  primitive  hygienic  requirements 
should  have  their  places  cleaned  up 
for  them  at  their  own  expense. 

Where  it  is  not  practicable  to  re- 
move manure,  it  may  be  kept  cov- 
ered in  a  dark  place,  which  discour- 
ages the  visitation  and  breeding  of 
flies,  and  in  addition  should  be  care- 
fully screened.  Larvae  may  be  de- 
stroyed. The  best  results  are  ob- 
tained by  the  use  of  borax  (sodium 

borate)  and  calcined  colemanite  (crude  calcium  borate).^  Both  sub- 
stances possess  a  marked  larvacidal  action  and  appear  to  exert  no  per- 
manent injury  on  bacteria.  In  order  to  kill  fly  eggs  and  maggots,  apply 
0.63  pound  borax  or  0.75  pound  calcined  colemanite  to  every  10  cu.  ft. 
(8  bushels)  of  manure  immediately  on  its  removal  from  the  barn.  Apply 
the  borax  particularly  around  the  outer  edges  of  the  pile  with  a  flour  sieve 
or  any  fine  sieve  and  sprinkle  two  or  three  gallons  of  water  over  the  borax 
treated  mass.  As  the  maggots  congregate  at  the  outer  edges  of  the 
pile,  most  of  the  borax  should  be  applied  there.  The  treatment  should 
be  repeated  with  each  addition  of  fresh  manure.  Borax  may  also  be 
applied  to  floors  and  crevices  in  barns,  markets,  stables,  etc.,  as  well  as 
to  street  sweepings.  The  borax  does  not  appear  to  injure  the  fertilizing 
value  of  the  manure. 


-The  Hodge  Fly  Trap  on 
Garbage  Can. 


*The  United  States  Department  of  Agriculture  {Bull,  of  the  U.  8.  Dept.  Agri- 
culture, No.  118,  July  14,  1914). 


256  INSECT-BOENE    DISEASES 

Unsatisfactory  results  were  obtained  l)y  the  use  of  kerosene,  iron 
sulphate,  potassium  eyanid,  coi)per  sulphate,  lime  sulphur  mixture,  Paris 
green,  sodium  fluorite,  formaldehyd,  and  the  Isthmian  Canal  Commission 
larvicide. 

Flies  are  thirsty  insects  and  will  be  attracted  to  a  saucer  of  water 
containing  a  little  formalin  (4  per  cent.).  This  simple  measure  will 
kill  many  of  them  in  a  room.  The  salts  of  barium,  cobalt,  and  other 
poisons,  such  as  arsenic,  potassium  bichromate,  o^  quassia  infusion,  may 
be  used  instead  of  formalin,  and  are  better  bait  if  sweetened.  Sticky 
fly-paper,  fly  traps,  electric  fans,  and  other  well-known  measures  will  help 
dispose  of  a  certain  number  of  flies,  but  all  these  measures  are  tentative, 
and  attack  the  problem  at  the  wrong  end. 

The  fly  has  a  number  of  natural  enemies :  various  fungi,  especially 
one  belonging  to  the  Entomopliilioreae,  which  destroys  flies  in  the  au- 
tumn. Flies  also  harbor  protozoa  and  nematodes  as  parasites,  which, 
however,  seem  to  do  them  little  harm.  The  little  bright  red  objects  often 
seen  attached  to  flies  are  mites,  which  are  usually  only  temporary  ecto- 
parasites stealing  a  free  ride.  When  spider  webs  are  not  disturbed  they 
catch,  and  the  spiders  devour,  a  large  number  of  flies.  The  house  centi- 
pede (Scutigera)  also  sometimes  catches  and  eats  flies,  as  do  the  com- 
mon garden  toad,  some  lizards,  and  a  few  insectivorous  birds. 

Flies  and  similar  dipterous  insects  are  responsible  for  the  transmis- 
sion of  a  large  number  of  diseases,  most  of  which  are  discussed  else- 
where. It  now  remains  to  consider  sleeping  sickness,  transmitted  by 
the  tsetse  fly  (Glossina  palpalis),  and  pappataci  fever,  transmitted  by 
a  biting  dipterous  insect  (Phlehotomus  pappatasii).  For  convenience 
a  general  consideration  of  the  trypanosomes  is  inserted  in  this  chapter. 

SLEEPING  SICKNESS 

Sleeping  sickness  was  limited  to  tropical  Africa,  especially  in  the 
Congo,  on  the  shores  of  Victoria  Nyanza,  and  about  the  head  waters 
of  the  Nile,  but  is  gradually  spreading.  Many  thousands  have  perished 
from  this  infection,  caused  by  Trypanosoma  gambiense  and  transmit- 
ted by  the  tsetse  fly  (Glossina  palpalis).  The  disease  is  characterized 
by  two  stages:  in  the  first  there  are  irregular  fever,  glandular  enlarge- 
ments, an  erythematous  rash,  and  localized  edemas.  In  the  second 
there  are  slowly  increasing  lethargy  and  other  morbid,  nervous  symp- 
toms. After  a  chronic  course  sleeping  sickness  usually  terminates  in 
death;  few  cases  recover.  Many  instances  of  fatal  homesickness  in  the 
negroes  during  the  slave  trade  are  now  believed  to  have  been  this  disease. 

The  Trypanosoma  gamMense  was  discovered  by  Button  in  1901  dur- 
ing the  first  or  febrile  stage  of  sleeping  sickness,  and  subsequently 
studied  by  Button  and  Todd,  who  did  not  at  first  suspect  the  relation 


FLIES 


257 


of  the  trypanosome  to  sleeping  sickness.  This  was  shown  by  Castellane 
in  1903.  Tlie  trypanosomes  are  found  in  the  cerebrospinal  fluid,  in 
the  enlarged  lymphatic  glands,  and  also  in  the  circulating  blood.  It 
seems  that  when  the  trypanosomes  are  inoculated  through  the  skin  by 
the  tsetse  fly  they  are  temporarily  blocked  by  the  lymphatic  glands. 
From  here  small  numbers  of  them  pass  into  the  circulation  and  thus 
to  other  parts  of  the  body.  They  are  always  in  the  fluids;  never  in  the 
cells  or  tissues.  ISTovy  and  McNeal  in  1903  accomplished  the  remarkable 
feat  of  growing  trypanosomes  in  the  water  of  condensation  of  blood 
agar  tubes.  Pure  cultures  show  marked  differences  between  the  Trypano- 
soma lewisi  of  the  rat 
and  the  Trypanosoma 
grussei  of  horses  and 
other  domestic  animals. 
So  far  no  one  has  suc- 
ceeded in  cultivating  the 
Trypanosoma  gambiense 
in  artificial  culture  me- 
dia. 

Sleeping  sickness  in 
Rhodesia  is  caused  by 
Trypanosoma  rhodesiense 
(Stephens  and  Fantham, 
1910),  transmitted  by 
Gl  0  s  sina  morsitans 
(Kinghorn     and     York, 

1912).     The  disease  in  Ehodesia  is  similar  to  that  in  the  Gambia;  fur- 
thermore, the  parasites  and  tsetse  flies  of  both  are  closely  allied  species. 

The  relation  of  the  tsetse  fly  to  the  transmission  of  this  disease 
rests  upon  satisfactory  evidence.  Button  and  Todd,  as  well  as  others, 
find  these  flies  abundant  wherever  sleeping  sickness  exists.  Wherever 
the  Glossina  palpalis  is  absent  sleeping  sickness  never  spreads,  as  Koch 
observed;  while,  on  the  other  hand,  if  a  case  is  brought  to  a  locality 
where  the  tsetse  fly  prevails,  it  soon  spreads.  It  is  probable  that  the 
transmission  by  the  tsetse  fly  is  not  of  the  simple  mechanical  type,  but 
that  the  parasite  undergoes  a  sexual  evolution  within  the  insect.  Flies 
seem  to  lose  their  power  of  transmission  soon  after  feeding  on  an  infected 
animal,  and  Bruce  considers  it  thoroughly  impossible  that  mechanical 
transmission  alone  could  explain  the  situation.  Kleine's  experiment  on 
monkeys,  conflrmed  by  Bruce,  showed  that  the  flies  may  convey  the 
disease  21  days  after  one  feeding  upon  a  monkey  infected  with  sleeping 
sickness.  In  another  experiment  by  Taute,  which  is  reported  by  Kleine, 
infection  was  produced  on  each  of  the  first  three  days  after  feeding.  From 
the  fourth  to  the  tenth  day  no  infection  resulted.  The  flies  then  became 
10 


Fig.  38. — Tsetse  Fly  {Glossina  palpalis). 


258  INSECT-BORNE    DISEASES 

infective  again  and  produced  the  disease  from  the  eleventh  to  the  forty- 
fourth  day.  Kleine  ^  concludes  that  the  period  of  development  or  intrin- 
sic period  of  incubation  in  the  fly  is  about  20  days  or  a  little  less.  Flies 
remain  infective  at  least  75  days.  Not  all  flies  which  drink  blood  con- 
taining trypanosomes  become  infective.  The  proportion  is  about  1  in 
20.  Of  the  fl.ies  caught  in  nature  in  endemic  areas,  from  2  to  10  in  one 
thousand  are  capable  of  transmitting  the  disease  to  animals.  Novy  has 
emphasized,  and  Minchim  has  corroborated  the  fact,  that  tsetse  flies 
may  harbor  non-pathogenic  as  weW  as  pathogenic  trypanosomes,  a  fact 
which  impairs  the  value  of  a  great  deal  of  the  microscopic  work  which 
has  been  done.  As  a  means  of  avoiding  the  accident  of  dealing  with 
naturally  infected  flies,  it  is  best  to  use  those  which  have  been  bred 
and  raised  in  the  laboratory. 

Prevention. — The  prevention  of  sleeping  sickness  in  the  present  state 
of  our  knowledge  depends  first  upon  isolation  of  the  sick,  protecting 
both  the  sick  and  the  well  against  fly  bites,  and  the  suppression  of  the 
flies  themselves.  The  sick  should  be  isolated  in  a  location  where  Glos- 
sina  palpalis  is  absent,  or  in  a  well-screened  and  carefully  managed 
hospital.  It  is  especially  important  to  isolate  all  those  who  carry  the 
infection  in  the  early  stages  of  the  disease,  whether  they  feel  sick  or 
not.  It  is  not  sufficient  simply  to  isolate  those  who  have  enlarged 
glands,  but  careful  blood  examinations  must  be  made.  The  trypano- 
somes have  been  found  in  the  circulating  blood  of  persons  with  normal 
lymph  glands. 

All  persons  taken  to  the  hospital  and  detention  station  are  given  a 
thorough  treatment  with  atoxyl  (a  combination  of  arsenious  acid  and 
anilin  oil).  Atoxyl  is  one-tenth  as  toxic  and  contains  about  three  times 
as  much  arsenic  as  arsenious  acid  alone.  The  dose  is  from  %  to  3 
grains  (0.05-0.2  grams)  subcutaneously. 

The  extermination  of  the  tsetse  fly  seems  a  hopeless  task.  The  larvae 
remain  in  the  body  of  the  mother  fly  until  fully  developed  and  are  then 
dropped  on  moist  soil,  in  which  they  burrow  to  undergo  transformation  to 
the  adult  state;  therefore,  clearing  of  the  land  in  limited  locations 
largely  diminishes  the  number  of  flies.  Clearing  the  brush  exposes  the 
earth  to  the  sun,  and  the  surface  becomes  dry  and  hard,  so  that  flies  die 
during  the  pupal  period.  This  measure  has  limited  possibilities,  but  is 
useful,  as  Shirata  points  out,  around  ports,  in  the  neighborhood  of  vil- 
lages, wharves,  and  other  places. 

The  tsetse  fly  may  also  be  fought  by  suppressing  its  food  supply.  It 
must  obtain  the  blood  of  some  vertebrate  animal  every  two  or  three  days. 
The  German  Commission  has  shown  that  on  the  banks  of  the  Victoria 
Nyanza  the  tsetse  fly  lives  largely  upon  crocodile  blood.  This  fact  was 
discovered  by  the  interesting  observation  that  the  flies  frequently  con- 

^Bull.  of  the  Sleeping  Sickness  Bureau,  No.  7,  1909. 


FLIES 


259 


tain  parasites  peculiar  to  the  crocodile's  blood.  Koch  believes  that  the 
disease  may  be  successfully  controlled  by  destruction  of  the  crocodileS;, 
a  theory  which  later  research  has  rendered  very  unlikely. 

Todd  and  Wolbach  ^  suggest  a  systematic  examination  of  the  natives 
in  the  endemic  area  by  gland  palpation  and  gland  puncture.     The  latter 


Fig.  39. 


Culicoides  milnei,  Austen. 
Culicoides  grahamii,  Austen. 
Simulium  latipes,  Mg. 
Simulium  wellmanni,  Roubaud. 


-Various  Gnats 

2.  Culicoides  brucei,  Austen. 

4.  Phlebotomus  duboscqi,  Neven-Lemaire 

6.  Simulium  damnosum,  Theob. 

8.  Simulium  griseicoUis,  Becker. 


Simulium  has  been  accused  of  transmitting  pellagra;  Phlebotomus  of  pappataci  fever. 


consists  in  withdrawing  a  drop  of  fluid  from  one  of  the  enlarged 
lymphatic  glands  by  means  of  a  hypodermic  syringe.  The  little  drop 
of  bloody  fluid  thus  obtained  is  examined  as  a  fresh  preparation  under 
the  microscope  for  trypanosomes.  By  this  method  these  investigators 
found  at  least  0.8  per  cent,  of  the  population  of  the  Gambia  to  harbor 

^Annals  of  Tropical  Medicine  and  Parasitology,  Vol.  V,  No.  2,  Aug.,  1911, 
p.  245. 


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260 


FLEAS  361 

trypanosomes.  If  all  the  infected  individuals  could  be  collected  in  vil- 
lages for  observation,  treatment,  and  isolation,  it  would  do  much  to 
limit  the  disease. 

Trypanosomes  are  the  cause  of  numerous  other  diseases  in  animals, 
as  will  be  seen  by  reference  to  the  table  on  page  260.  So  far  as  known, 
sleeping  sickness  is  the  only  important  disease  of  man  produced  by 
trypanosomes.  Kala-azar,  however,  is  produced  by  a  flagellated  proto- 
zoon  parasite  which  probably  belongs  to  the  trypanosomes. 

Practically  all  animals  are  susceptible  to  almost. all  trypanosomes. 
The  trypanosomes  which  infect  man  may  readily  be  transmitted  to  mon- 
keys, guinea-pigs,  rabbits,  etc. 

PAPPA TA CI  FE VER 

Doerr  and  Russ  ^  and  also  Doerr,  Franz,  and  Taussig  originally  de- 
scribed a  three-day  fever  which  occurs  on  the  shores  of  the  Mediterranean, 
also  known  in  India,  Egypt  and  South  America.  The  cause  of  pappataci 
fever,  or  sand-fly  fever,  is  not  known,  but  is  of  special  interest  for  the 
reason  that  it  has  been  demonstrated  to  be  transmitted  through  the  bite 
of  a  dipterous  insect  commonly  called  a  gnat — Plilehotomus  pappatasii. 
This  little  insect  only  bites  in  darkness  and  only  in  houses.  Prevention 
consists  in  using  a  fine  mosquito  netting,  and  insecticidal  agents  (see 
page  233). 

FLEAS 

Fleas  are  latterly  flattened,  wingless  creatures  related  to  the  Diptera. 
They  pass  through  a  complete  metamorphosis:  egg,  larva,  pupa,  and 
imago.  The  adult  female  flea  deposits  her  eggs  among  the  hair  or  fur 
of  the  host  animal,  but,  unlike  the  eggs  of  many  ectoparasites,  they  are 
not  fastened  to  the  hairs  and  therefore  fall  freely  to  the  ground.  The 
eggs  are  oval,  whitish,  and  smooth  and  about  half  a  millimeter  long.  The 
larvae  escape  from  the  eggs  in  2  to  5  days.  They  are  able  to  break  the 
egg  shell  by  a  slender  process  on  the  top  of  the  head  which  disappears 
after  the  first  molt.  The  larva  is  a  slender,  legless,  cylindrical  creature, 
whitish  or  yellowish  in  color,  with  a  head  and  13  segments.  There  are  a 
few  scattered  hairs  or  bristles  on  the  body,  and  at  the  tip  is  a  pair  of  cor- 
neus  processes.  At  the  front  of  the  head  is  a  pair  of  biting  jaws  or 
mandibles.  The  larvae  feed  on  almost  any  kind  of  refuse.  They  have 
been  reared  on  the  sweepings  from  rooms.  There  is  always  some  or- 
ganic matter  in  such  dust,  and  this  is  doubtless  their  nourishment.  In 
houses  the  larvae  usually  crawl  into  cracks  or  in  carpets,  where  they  feed 

^Schiffs  und  Tropen  Hyg.,  1909,  Vol.  XIII.  No.  22,  p.  693. 


263 


INSECT-BORNE    DISEASES 


and  grow.  Those  that  infest  wild  animals  probably  feed  on  the  refuse 
in  the  nests  or  retreats  of  these  animals.  It  will  be  noticed  that,  con- 
trary to  the  mosquito,  the  larval  and  pupal  stages  of  the  flea  are  not 
aquatic.  They  remain  in  the  larval  stage  from  a  week  to  ten  days, 
sometimes  two  weeks,  molting  the   skin  three  times  in  this  interval. 


Fig.  40. — The  Indian  Rat  Flea  {Xenopsylla  cheopis  Rothsc). 


Then  they  spin  flat,  white,  silken  cocoons  in  which  they  transform  to 
the  pupal  stage.  In  from  5  to  8  days  the  adult  flea  emerges  from  the 
cocoon.  The  period  of  their  transformation  is  affected  by  the  tempera- 
ture and  moisture.  In  warm,  damp  weather  a  generation  may  develop 
in  ten  days  or  two  weeks,  but  usually  about  18  days  to  three  weeks 


Fig.  41. 


-The   Common   Rat  Flea  op  Europe   and   North  America    {Ceratophyllu 
fasciatus  Bosc). 


elapse  from  the  egg  to  the  adult.     Although  some '  moisture  is  neces- 
sary for  their  development,  an  excess  is  apt  to  destroy  the  larvae. 

The  leaping  ability  of  adult  fleas  is  familiar  to  all.  This,  however, 
has  been  greatly  exaggerated.  The  British  Plague  Commission  de- 
termined that  fleas  jump  3  to  5  inches,  never  over  6.     No  part  of  the 

^  Formerly  Loemopsylla  cheopis. 


FLEAS 


263 


leg  is  particularly  enlarged,  so  that  the  jump  is  made  by  the  entire  leg,  as 
in  the  leaf-hopper  insect,  and  not  by  the  femur  of  the  hind  leg,  as  in 
the  grass-hopper.  Fleas  do  not  vary  much  in  size.  They  are  mostly 
about  2  to  3  millimeters  long.  The  adult  insect  has  a  hard,  strongly 
chitinized  body.  The  mouth  parts  resemble  somewhat  those  of  the  mos- 
quito. Both  the  male  and  the  female  flea  are  capable  of  piercing  the  skin 
to  obtain  blood  and  thus  transmit  infection.  Fleas,  as  a  rule,  prefer 
certain  hosts,  but  are  not  as  particular  in  this  regard  as  are  many  para- 
sites. Those  species  which  are  best  known  are  found  to  attack  several 
hosts,  including  man.  This  is  one  reason  that  makes  them  dangerous 
parasites,  so  far  as  plague  and  other  infections  are  concerned.  Over  300 
species  are  described.  Formerly  all  fleas  were  classified  in  the  single 
family  Pulicidae,  genus  Pulex;  now  they  are  arranged  in  many  genera 


Fig.  42. — The  Human  Flea  (Pulex  Irritans  Linn.). 

and  these  genera  grouped  into  families.^  Pulex  serraticeps  or  Ctenoce- 
phaltis  canis  occurs  all  over  the  world,  infesting  cats  and  dogs,  also  many 
other  animals.  They  are  frequently  brought  into  houses  upon  domestic 
animals,  and  thus  become  troublesome  to  man.  Pulex  irritans  is  the 
human  flea,  sometimes  called  the  "house  flea"  or  "common  flea."  The 
fleas  concerned  in  the  transmission  of  plague  are  Xenopsylla  cheopis,  the 
Indian  rat  flea,  and  Ceratophyllus  fasciatus,  the  common  rat  flea  of 
Europe  and  North  America.  Plague  may  also  be  transmitted  by  Cteno- 
cephalus  felis,  the  cat  flea ;  Pulex  irritans,  the  human  flea ;  Ceratophyllus 
acutus,  the  squirrel  flea,  and  doubtless  other  genera  and  species. 

In  addition  fleas  act  as  intermediate  hosts  for  certain  tapeworms 
(Dipylidium  caninum),  and  doubtless  are  the  mechanical  or  biological 
carriers  of  other  infections.  Kicolle  incriminates  the  flea  in  typhus 
fever. 


^  Banks: 
H.  S.,  p.  69. 


"The  Eat  and  Its  Relation  to  the  Public  Health/'  P.  H.  and  M. 


264  INSECT-BOENE    DISEASES 

Pulicides.— Adult  fleas  succumb  to  the  agents  applicable  to  insects 
in  general.  Mitzmain  ^  has  shown  that  water  is  of  little  value  in 
the  destruction  of  mature  fleas.  Glycerin  is  also  practically  inert  as  a 
pulicide,  but  tincture  of  green  soap  is  very  quick  and  effective.  Kerosene 
(coal  oil)  is  a  very  efficient  flea  destroyer.  Formalin,  phenol,  mercuric 
bichlorid,  and  tricresol  in  the  strength  used  as  disinfectants  are  of  little 
value  in  killing  fleas.     Powdered  sulphur  seems  to  be  of  no  value. 

Of  gases,  bisulphid  of  carbon  (CS,),  hydrocyanic  acid  gas  (HCN), 
and  sulphur  dioxid  (SOg)  are  highly  efficient  in  the  strengths  recom- 
mended for  general  insecticidal  purposes.  Chloroform  or  ether  first 
anesthetizes  fleas,  and  if  continued  kills  them.  This  is  important  for 
the  safe  handling  of  rats,  squirrels,  and  other  plague  animals.  The 
host  may  be  chloroformed  and  the  fleas  and  other  ectoparasites  removed 
with  a  comb.  The  anesthetic  may  be  controlled  by  practice  so  that  the 
host  will  recover  and  the  fleas  die,  or  both  recover,  or  both  die,  as  may 
be  desired. 

In  flea-infected  houses  the  larvae,  living  in  the  cracks  of  the  floor, 
etc.,  may  be  controlled  by  sprinkling  a  thin  coating  of  flake  naphthalene 
on  the  floor  and  then  leaving  the  room  tightly  closed  over  night.  In, 
the  morning  the  naphthalene  may  be  swept  wp  and  what  remains  used 
again. 

Kitasatc  ^  confirms  the  efficacy  of  the  method  of  collecting  rat  fleas 
by  turning  guinea-pigs  loose  in  a  building.  The  fleas  collect  upon  the 
guinea-pigs  and  both  the  fleas  and  the  pigs  may  then  be  examined  for 
plague  bacilli. 


RELATION  OF  PLAGUE  TO  RATS  AND  FLEAS 

Plague  is  primarily  a  disease  of  the  rat  and  secondarily  of  man. 
This  fact  is  now  firmly  established  not  only  by  the  recent  experiences, 
but  especially  through  the  admirable  studies  of  the  Indian  Plague  Com- 
mission,^ which  established  beyond  doubt  the  fact  that  plague  may  be 
and  generally  is  transmitted  from  rat  to  rat  and  from  rat  to  man 
through  the  agency  of  the  flea — Xenopsylla  cheopis — and  sometimes  by 
Ceratophyllus  fasciatus,  et  al.  During  some  plague  epidemics  it  has  been 
noted  that  the  rats  die  in  great  numbers  before  and  during  the  out- 
break. It  is  now  known  that  this  epizootic  in  the  rat  is  true  plague. 
In  nature,  rats  suffer  both  with  acute  and  chronic  plague. 

In  the  laboratory,  rats  may  be  infected  with  plague  by  ingestion,  by 
application  of  the  virus  to  mucous  or  cutaneous  surfaces,  or  by  sub- 

^  Public  Health  Reports,  July  29,  1910,  Vol.  XXV,  No.  30,  p.  1039. 
^  Kitasato,  S. :     "Bubonic  Plague  and  Rat  Fleas."    Berl.  klin.  Wchnschr.,  Oct. 
13,  L,  41,  pp.    1881-1928. 

^^ Journal  of  Hygiene,  Vol.  VI,  No.  4;  Vol.  VII,  Nos.  3,  6;  Vol.  VIII,  No.  2. 


EELATION  OF  PLAGUE  TO  EATS  AND  FLEAS   265 

cutaneous  inoculation.  In  nature,  rats  may  become  infected  by  any  of 
these  means,  but  probably  flea  transmission  is  the  only  one  that  ordinarily 
operates  to  any  extent. 

Eats  are  great  travelers,  and  have  carried  the  plague  to  all  quarters 
of  the  globe.  A  more  complete  discussion  of  the  rat  and  its  relation 
to  plague  and  other  diseases  will  be  found  on  page  369. 

Within  the  past  few  years  it  has  been  discovered  that,  while  the 
rat  is  the  great  medium  for  the  spread  of  plague,  the  disease  was  prob- 
ably preserved  from  extinction  in  Thibet  by  another  rodent,  the  marmot 
(Arctomys  bohac).  The  tarbagan,  a  fur-bearing  rodent,  infected  trap- 
pers and  traders,  who  in  turn  started  the  epidemic  of  pneumonic  plague 
in  Manchuria  in  1910-1911.  In  California  the  infection  has  gotten  into 
the  ground  squirrels  (Citellus  beecheyi),  in  which  the  disease  will  doubt- 
less be  kept  alive  for  many  years  to  come.     To  realize  the  full  impor- 


FiG.  43. — A  Squirrel  Flea  (Hoplopsyllus  anomalus  Baker.). 


tance  of  these  discoveries,  it  is  only  necessary  to  call  to  mind  that,  in 
order  to  eradicate  plague  forever  from  the  surface  of  the  globe,  a  war- 
fare against  the  rat  alone  is  not  sufficient,  but  must  include  the  rodents 
mentioned  and  perhaps  others. 

Simond  in  1897  advanced  the  theory  that  plague  was  carried  by 
fleas.  This  theory  was  developed  by  J.  Ashburton  Thompson  and  others 
and  conclusively  proved  by  the  Indian  Plague  Commission.  The  exact 
method  by  which  the  flea  transmits  the  infection  from  animal  to  ani- 
mal is  not  definitely  understood.  The  mouth  parts  appear  not  to  re- 
main infected.  It  is  possible  that  the  salivary  secretions  contain  the 
microorganisms.  It  is  known  that  the  plague  bacilli  may  live  in  the 
digestive  tract  and  be  passed  in  live  and  virulent  numbers  in  the  de- 
jecta. It  is  easy  to  understand  how  some  of  the  infected  dejecta  may 
be  rubbed  or  scratched  into  the  little  wound  produced  by  the  flea 
bite. 

Bacot  and  Martin  ^  found  that  Xenopsylla  clieopis  and  Ceratophyllus 

^Jour.  of  Eyg.,  Plague  Supplement,  III,  p.  423,   1914. 


266  INSECT-BORNE    DISEASES 

fasciatus  may  transmit  plague  during  the  act  of  sucking  by  regurgitating 
some  of  the  blood.  These  investigators  found  that  in  a  proportion  of 
infected  fleas  the  plague  bacilli  developed  to  such  an  extent  in  the  esopha- 
gus and  proventriculus  as  to  occlude  the  alimentary  canal  at  the  entrance 
to  the  stomach.  Fleas  in  this  condition  are  not  prevented  from  sucking 
blood  as  the  pump  is  in  the  pharynx,  but  they  only  succeed  in  distending 
an  already  obstructed  esophagus,  and  on  cessation  of  the  pumping  act 
some  of  the  blood  is  forced  back  into  the  wound.  Such  fleas  are  per- 
sistent in  their  endeavors  to  feed,  and  this  renders  them  particularly 
dangerous. 

When  it  was  found  that  the  common  rat  flea  of  Europe,  the  Cera- 
topJiylltis  fasciatus,  does  not  readily  bite  man,  considerable  doubt  was 
thrown  upon  the  part  played  by  the  flea  in  plague  transmission.  These 
negative  results,  however,  are  offset  by  the  convincing  positive  proofs 
of  the  British  Plague  Commission  in  India,  and  by  McCoy  and  Mitz- 
main  in  San  Francisco,  who  showed  that  under  certain  conditions  the 
rat  flea  will  bite  man,  especially  if  the  natural  food  supply  is  limited, 
and  that  these  fleas  may  feed  on  a  man's  hand  even  in  the  presence  of 
a  rat. 

Raybaud^  calls  attention  to  the  fact  that  the  rat  flea  {Ceratophyllus 
fasciatus)  is  able  to  hibernate  for  a  month  or  45  days  without  nourish- 
ment, and  that  virulent  plague  germs  may  persist  unharmed  in  its 
stomach  during  this  length  of  time  and  even  longer.  This  fact  may 
be  of  importance  for  the  transmission  of  plague  to  a  distance. 

Bacot  and  Martin  ^  found  that  infected  fleas  which  were  fed  regu- 
larly might  live  for  50  days,  at  from  10  to  15°  C.  and  23  days  at  27°  C. 
and  remain  infected  at  death. 

The  Commission  for  the  Investigation  of  the  Plague  in  India  ^  found 
that  infection  conveyed  by  fleas  might  take  place  three  weeks  after  the 
flea  population  had  any  opportunity  of  imbibing  infected  blood.  Bacot  * 
has  observed  that  fleas  (Ceratophyllus  fasciatus)  are  able  to  carry  the 
bacillus  of  plague  for  periods  up  to  47  days  and  subsequently  infect  a 
mouse. 

The  indications,  thus,  are  that  plague  infection  may  persist  in  fleas 
at  least  1  or  2  months  in  cold  weather  and  subsequently  give  rise  to  an 
epizootic. 

Ii  should  be  remembered  that,  according  to  the  observations  of  Nut- 
tall  and  Yersin,  flies  and  possibly  other  insects  may  also  occasionally 


^Presse  Medicate,  March  8,  1911,  No.  20. 

'Jour.  A.  M.  A.,  Apr.  10,  1915,  LXIV,  15,  p.  1251. 

*  Reports  on  Plague  Investigations  in  India,  Jour.  Eyg.,  1906,  VI,  435. 

*  Observations  on  the  length  of  time  that  fleas  (Ceratophyllus  fasciatus) 
carrying  Bacillus  pestis  in  their  alimentary  canals  are  able  to  survive  and  retain 
the  power  to  reinfect  with  plague.  Jour.  Hyg.,  Plague  Supplement  IV,  1915,  770. 


EATS  AND  OTHEE  EODENTS  267 

convey  the  infection.  Walker^  considers,  as  the  result  of  experiments, 
that  bedbugs  and  other  biting  insects  play  an  important  role  in  the 
transmission  of  plague.  Bacot  ^  has  demonstrated  that  bedbugs  are 
capable  of  carrying  Bacillus  pestis  and  may  thus  infect  mice  after  a 
period  of  48  days'  starvation. 


RATS    AND    OTHER    RODENTS 

Eats,  mice,  squirrels,  and  other  rodents  have  become  a  serious  prob- 
lem in  preventive  medicine,  and  their  habits  and  methods  of  suppression 
may  be  considered  conveniently  at  this  place.  Plague  being  primarily 
a  disease  of  rats,  the  prevention  and  suppression  of  this  infection  re- 
solve themselves  into  a  war  upon  these  rodents.  For  the  control  of  plague 
it  is,  therefore,  necessary  to  have  a  knowledge  of  the  life  history  and 
methods  of  attacking  the  problem  in  the  lower  animals.  In  addition  to 
plague,  rats  are  the  great  reservoir  of  trichinosis.  They  are  responsible 
for  the  transmission  of  certain  tapeworms  and  other  parasites.  They 
are  subject  to  leprosy,  cancer,  and  numerous  other  diseases,  some  of 
which  concern  man. 

Eodents  comprise  more  than  one-third  of  all  living  species  of  mam- 
mals, and  exceed  any  other  mammalian  order  in  the  number  of  in- 
dividuals. They  have  no  canine  teeth,  but  strongly  developed  incisors. 
Only  the  front  of  the  incisors  is  covered  with  enamel,  which  keeps 
them  sharp  and  chisel-like,  owing  to  the  more  rapid  wearing  away  of 
the  softer  dentine.  The  incisor  teeth  continue  to  grow  throughout  the 
life  of  the  animal.  The  most  extensive  family  of  rodents  is  the  Muridae, 
which  includes  the  true  rats  and  mice,  typified  by  the  genus  Mus. 
Trouessart,  in  his  "Catalogus  mammalium,"  enumerates  250  species  of 
Mus  described  before  1905.  Since  that  date  a  number  of  new  forms 
have  been  described. 

The  genus  Mus  is  characterized  by  narrow,  ungrooved  incisors ;  three 
small-rooted  molars;  soft  fur  mixed  with  hairs,  sometimes  with  spines; 
a  rudimentary  pollex  (thumb)  having  a  short  nail  instead  of  a  claw; 
a  long  tail  bearing  rings  or  overlapping  scales  and  often  naked  or 
nearly  so.  The  ears  are  rather  large,  the  eyes  bright  and  prominent, 
and  the  muzzle  somewhat  pointed. 

The  distinction  between  rats  and  mice  is  arbitrary  and  based  on 
size.  Of  the  many  species  of  the  genus  Mus  only  three  or  four  have 
developed  the  ability  to  adapt  themselves  to  such  a  variety  of  condi- 
tions as  to  become  cosmopolitan.    Four  have  found  lodgment  in  America : 

» Walker:    Indian  Med.  Gaz.,  1910,  No.  3,  p.  93. 

'Notes  on  the  Development  of  Bacillus  Pestis  in  Bugs  (Cimex  Lectularius) 
and  Their  Power  to  Convey  Infection,  Jour,  Hyg.,  Plague  Supplement  IV,  1915, 
p.  779. 


268  INSECT-BORNE    DISEASES 

The  common  house  mouse,  Mus  musculus. 

The  English  black  rat,  Mus  rattus. 

The  Egyptian  or  roof  rat,  Mus  alexandrimis. 

The  brown  rat,  Mus  norvegicus  (formerly  decumanus). 

The  black  rat  and  the  roof  rat  differ  from  each  other  mostly  in 
color,  and  some  zoologists  regard  them  as  races  of  the  same  species. 
The  brown  rat  is  also  known  as  the  gray  rat,  barn  rat,  wharf  rat,  sewer 
rat,  and  Norway  rat. 

The  black  rat  (1/us  rattus)  has  been  known  in  Europe  since  the 
twelfth  century,  and  from  there  has  been  carried  to  America.  The 
brown  rat  (Mu^  norvegicus)  came  later,  and,  as  it  is  more  destructive, 
larger,  and  more  ferocious,  it  is  rapidly  driving  the  black  rat  before  it. 
The  brown  rat  differs  somewhat  in  habits  from  the  black  rat,  especially 
in  that  it  burrows,  which  protects  it  against  its  enemies  and  renders  its 
suppression  more  difficult. 

The  house  mouse  holds  its  own  everywhere  against  the  brown  or 
Norway  rat,  as  it  is  able  to  get  into  holes  too  small  for  the  rat  to  fol- 
low. Albinism  and  melinism  occur  in  all  species;  pied  forms  are  com- 
mon. The  white  rat  of  the  laboratory  is  an  albino  form  of  either  Mus 
rattus  or  Mus  norvegicus. 

Breeding  and  Prevalence.— The  brovm  rat  is  more  prolific  than 
either  the  roof  rat  or  the  black  rat.  The  brown  rat  reproduces  from 
three  to  five  times  a  year,  each  time  bringing  forth  from  six  to  nine, 
and  sometimes  as  many  as  22  or  23,  young.  They  breed  more  rapidly 
in  temperate  and  equable  climates  than  in  those  of  great  variability. 
The  number  of  rats  is  only  limited  by  the  food  supply  and  opportu- 
nities to  nest.  Few  people  have  any  conception  of  the  enormous  num- 
bers of  rats  in  cities  and  on  farms.  Although  few  are  seen  in  the  day 
time,  at  night  they  fairly  swarm  along  river  fronts  and  wharves,  as 
well  as  in  sewers,  stables,  warehouses,  markets,  and  other  places  where 
food  may  be  found.  A  few  instances  will  illustrate  the  prolific  habits 
and  give  an  idea  of  the  destructive  tendency  of  rats. 

In  1901  an  estate  near  Chichester,  England,  was  badly  infested  with 
rats;^  31,981  were  killed  by  traps,  poisons,  and  ferrets,  while  it  is  esti- 
mated that  tenants,  at  the  threshing,  destroyed  fully  5,000  more.  Even 
then  the  property  was  by  no  means  free  from  rats. 

During  the  plague  of  rats  on  the  island  of  Jamaica,  in  1833,  the 
number  killed  on  a  single  plantation  in  a  year  was  38,000."  The  in- 
jury to  sugar  cane  on  the  island  caused  by  the  animals  was  at  that  time 
estimated  at  half  a  million  dollars  a  year. 

The  report  of  the  Indian  Famine  Commission  in  1881  affords  one 

^The  Field,  London,  Vol.  C,  p.  545,  1902. 
'New  England  Farmer,  Vol.  XII,  p.  315,  1834, 


EATS  AND  OTHEE  EODENTS  269 

of  the  best  illustrations  of  the  number  of  rats  that  may  infest  a  coun- 
try. An  extraordinary  number  of  the  animals  at  that  time  inhabited 
the  Southern  Deccan  and  Mahratta  districts  of  India.^  The  autumn 
crop  of  1878  and  the  spring  crop  of  1879  were  both  below  the  average, 
and  a  large  portion  of  each  was  destroyed  by  rats.  The  resulting  scarcity 
of  food  led  to  the  payment  of  rewards  for  the  destruction  of  the  pests, 
and  over  12,000,000  were  killed. 

Miration. — The  migrations  of  rats  have  often  been  recorded.  The 
brown  rat  is  known  in  Europe  quite  generally  as  the  migratory  rat; 
the  Germans  call  it  the  Wanderratte.  Pallas  relates  that  in  the  autumn 
of  1772  they  arrived  from  the  East  at  Astrakhan,  southeastern  Eussia, 
in  such  great  numbers  and  so  suddenly  that  nothing  could  be  done  to 
oppose  them.  They  crossed  the  Volga  in  immense  troops.  The  cause 
of  this  general  migration  was  attributed  to  an  earthquake,  but,  since 
similar  movements  of  the  same  species  often  occur  without  earthquakes, 
it  is  probable  that  only  the  food  supply  of  the  animals  was  involved 
in  the  migration  which  first  brought  the  brown  rat  to  Europe. 

Seasonable  movements  of  rats  from  houses  and  barns  to  the  open 
fields  take  place  in  the  spring,  when  green  and  succulent  plant  food  is 
ready  for  them.  The  return  movement  takes  place  in  the  autumn. 
This  seasonal  migration  is  notable  even  in  large  cities.  In  1903  a 
multitude  of  migrating  rats  spread  over  several  counties  of  western 
Illinois.  They  traveled  in  great  armies  and  invaded  the  farms  and 
villages  of  Eock  Island  and  Mercer  counties,  and  caused  heavy  losses 
during  the  winter  and  summer  of  1901.  In  one  month  Mr.  Montgom- 
ery of  Mercer  county  killed  3,435  rats  on  his  farm.  He  caught  most  of 
them  in  traps. 

In  England  a  general  movement  of  rats  inland  from  the  coast  oc- 
curs every  October.  This  is  known  to  be  closely  connected  with  the 
closing  of  the  herring  season.  During  the  fishing  the  rodents  swarm 
to  the  coast  attracted  by  the  offal  left  in  cleaning  the  herring,  and 
when  this  food  fails  the  animals  troop  back  to  the  farms  and  villages. 

An  invasion  of  rats  (Mus  rattus)  in  the  Bermuda  Islands  occurred 
about  the  year  1615.  Within  two  years  they  had  increased  so  alarmingly 
that  none  of  the  islands  was  free  from  them.  The  rodents  "devoured 
everything  that  came  in  their  way — fruits,  plants,  and  even  trees" — so 
that  for  a  year  or  two^  the  people  were  nearly  destitute  of  food.  A  law 
was  passed  requiring  every  man  in  the  island  to  keep  12  traps.  In 
spite  of  all  efforts  the  animals  continued  to  increase  until  they  finally 
disappeared,  so  suddenly  that  it  is  supposed  they  must  have  been  vic- 
tims of  a  pestilence. 

While  stationed  upon  Angel  Island  in  San  Francisco  harbor  I  ob- 
served several  migrations  of  rats  between  the  army  post  and  the  quar- 

"■  British  Med.  Jour.,  Sept.  16,  1905,  p.  623. 


270  mSECT-BOENB    DISEASES 

antine  station,  which  were  about  a  mile  apart  and  separated  by  an  in- 
tervening ridge.  Everyone  is  familiar  with  the  sudden  invasion  of 
stores,  factories,  and  other  structures  with  these  rodent  pests,  which 
causes  considerable  economic  loss. 

On  Vesselsi. — Eats  are  found  on  all  vessels ;  they  are  great  travelers. 
It  is  through  this  seagoing  tendency  that  the  rat  has  become  cosmo- 
politan. Eats  get  on  board  vessels  readily  as  they  lie  at  their  dock; 
sometimes  they  are  carried  on  board  in  the  cargo. 

It  is  very  important  to  prevent  the  introduction  of  rats  on  vessels 
at  plague-infected  ports;  it  is 'also  important  to  prevent  the  passage  of 
rats  from  ship  to  shore,  particularly  if  the  vessel  is  from  a  plague  port. 
In  order  to  accomplish  this,  it  is  necessary  to  exercise  particular  care. 
In  extreme  cases  the  ship  should  not  approach  the  dock,  but  the  cargo 
should  be  handled  by  means  of  lighters.  When  the  ship  lies  at  its 
moorings  in  a  stream  or  in  the  open  bay  rats  may  get  on  board  by 
swimming,  and  climbing  in  through  the  hawse  pipe.  Eats  rarely  swim 
more  than  one-quarter  to  one-third  of  a  mile.  If  the  vessel  ties  up  at 
the  dock,  inverted  funnels  should  be  placed  on  the  hawsers.  The  gang- 
planks should  be  watched  during  the  day  and  always  taken  up  at  night. 
Vessels  from  plague  ports  should  always  be  treated  with  sulphur  dioxid, 
preferably  when  empty,  and  always  before  leaving,  and  also  en  route, 
to  kill  the  rats  that  may  be  on  board.  A  wise  measure  in  international 
sanitation  would  be  to  require  all  vessels,  whether  trading  at  plague 
ports  or  not,  to  fumigate  for  rats  no  less  than  three  or  four  times  a  year. 

Food. — Eats  are  not  strictly  herbivorous,  as  might  be  inferred  from 
their  dentition;  they  are  practically  omnivorous.  Their  bill  of  fare  in- 
cludes grains  and  seeds  of  every  kind ;  flour,  meal,  and  all  food  products 
made  from  them;  garden  vegetables,  mushrooms,  bark  of  growing  trees, 
bulbs,  roots,  stems,  leaves,  and  flowers  of  herbaceous  plants ;  eggs,  chick- 
ens, ducklings,  squabs,  and  young  rabbits,  milk,  butter,  and  cheese; 
fresh  meat  and  carrion;  fish,  frogs,  mollusks,  and  crustaceans;  they  are 
also  cannibals.  This  great  variety  of  food  explains  the  ease  with  which 
rats  maintain  themselves  in  almost  any  environment. 

Habits. — The  roof  rat  {Mus  alexandrinus)  and  the  black  rat  {Mus 
rattus)  are  more  expert  climbers  than  the  brown  rat,  which  is  larger 
and  clumsier.  In  buildings  the  brown  rat  keeps  mainly  to  the  cellar 
and  lower  parts,  where  it  commonly  lives  in  burrows.  From  these  re- 
treats it  makes  nightly  excursions  in  search  of  food.  The  roof  rat  and 
the  black  rat  live  in  the  walls  or  in  the  space  between  ceilings  and  roofs. 
Eats  readily  climb  trees  to  obtain  fruit.  In  the  tropics  the  roof  rat 
and  the  black  rat  habitually  nest  in  trees.  In  the  open,  rats  seem  to 
have  defective  vision;  by  daylight  they  move  slowly  and  uncertainly; 
on  the  contrary,  at  the  side  of  the  room  and  in  contact  with  the  wall 
they  run  with  great  celerity.     This  fact  suggests  that  the  vibrissae 


EATS    AND    OTHEE    EODENTS  271 

(whiskers)  serve  as  feelers,  and  that  the  sense  of  touch  in  them  is  ex- 
tremely delicate.  The  animals  always  prefer  narrow  places  as  high- 
ways— another  circumstance  which  may  be  made  use  of  in  placing 
traps. 

The  ferocity  of  rats  has  been  grossly  exaggerated.  The  stories  of 
their  attacks  upon  human  beings,  sleeping  infants  especially,  have  but 
slight  foundation.  Ordinarily  the  probability  of  being  bitten  by  rats  is 
remote,  and  the  bite  is  not  usually  poisonous.  Miyake  ^  has  described 
a  "rat-bite  disease,"  called  Sodoku  in  Japan,  or  rat-bite  fever. 

Rat-Bite  Fever. — Eat-bite  fever  ^  is  a  paroxysmal  febrile  disease  of 
the  relapsing  type  following  the  bite  of  a  rat.  It  is  due  to  Streptotlirix 
muris  ratti,  first  described  by  Schottmliller  in  1914.  The  wound  heals 
readily,  but  after  a  variable  incubation  period  of  a  few  days  to  a  month 
the  wound  becomes  inflamed  and  painful.  Lymphangitis  and  adenitis 
set  in  and  are  quickly  followed  by  symptoms  of  systemic  infection  ushered 
in  by  a  chill  and  rapid  rise  in  temperature.  A  characteristic  exanthem  of 
bluish  red,  erythematous,  sharply  marginated  macules  appears,  generally 
distributed.  About  10  per  cent,  of  the  cases  terminate  fatally,  usually 
during  the  first  febrile  period,  occasionally  later  from  nephritis  or  ex- 
haustion. 

Plague  in  Rats. — It  is  now  known  that  rat  fleas  are  responsible  for 
most  cases  of  human  plague  of  the  bubonic  type,  and  in  addition  are  the 
most  frequent  medium  by  which  plague  is  carried  from  one  locality  to 
another.  They  also  convey  the  plague  infection  to  other  rodents,  such 
as  ground  squirrels. 

The  clinical  manifestations  of  plague  in  rats  are  of  little  importance. 
It  is  generally  said  that  a  plague-infected  rat  staggers  about  with  a 
drunken  gait,  loses  fear  of  its  natural  enemies,  and  is  readily  captured. 
Eats  experimentally  infected  show  no  marked  manifestations  of  illness 
until  shortly  before  death,  when  they  become  quiet,  crouch  in  the  cor- 
ner of  the  cage,  and  try  to  hide.  It  is  rather  surprising  that  compara- 
tively few  dead  plague  rats  are  found  in  endemic  centers.  In  the  San 
Francisco  campaign  McCoy  estimates  that  certainly  not  more  than  20 
per  cent,  of  the  infected  rodents  were  found  dead,  the  remainder  being 
trapped. 

Eats  suffer  both  with  acute  plague  and  chronic  plague,  the  lesions 
of  which  differ. 

The  diagnosis  of  plague  in  rats  may  be  made  macroscopically.  The 
Indian  Plague  Commission,  which  had  the  opportunity  of  examining  an 
enormous  number  of  plague  rats  in  Bombay  and  elsewhere  in  India,  state 
that  "the  results  of  tests  carried  out  for  the  purpose  of  comparison 

*  Mitt.  a.  d.  Grenzgeh.  d.  Med.  u.  CMr.,  1902 ;  also  Proescher,  Internat.  Clin' 
ics,  IV,  25th  Series,  p.  77. 

^JourA.  Exp.  Medicine,  Vol.  XXIII,  No.  1,  January  1,  1916,  p.  39. 


272  INSECT-BOENE    DISEASES 

make  it  manifest  that  the  naked  eye  is  markedly  superior  to  the  micro- 
scopic method  as  an  aid  in  diagnosis,  and  as  the  result  of  our  experi- 
ence we  are  prepared  to  make  a  diagnosis  of  plague  on  the  strength  of 
the  macroscopical  appearance  alone,  even  though  the  other  results  of 
cutaneous  inoculation  and  culture  are  negative  and  the  animals  show 
signs  of  putrefaction."  The  experience  of  McCoy  and  others  in  the 
Federal  Plague  Laboratory  in  San  Francisco  leads  to  the  same  conclu- 
sion. It  should  be  remembered,  however,  that  occasionally  plague  oc- 
curs in  rats  without  gross  lesions.  This  has  been  observed  by  Dunbar 
and  Kister  and  also  by  McCoy.  In  any  critical  case  the  bacteriological 
confirmation  is  essential. 

Acute  plague  in  rats  is  characterized  by  engorgement  of  the  subcu- 
taneous blood  vessels  and  a  diffuse  pink  color  of  the  subcutaneous 
structures  and  muscles.  The  diagnosis  may  often  be  inferred  at  the 
first  incision.  The  lymphatic  glands  of  the  neck,  axilla,  groin,  or  pel- 
vis are  enlarged  and  frequently  surrounded  by  a  hemorrhagic  exudate 
and  edema.  The  liver  is  granular  with  focal  necroses,  the  spleen  en- 
larged and  friable,  and  pleural  effusions  are  common. 

Chronic  plague  in  rats  has  been  encountered  in  a  considerable  num- 
ber of  cases  among  Mus  rattus  in  the  Punjab  villages  of  Kasel  and 
Dhand.  It  has  not  been  found  in  California.  In  the  chronic  disease 
the  lesions  consist  of  purulent  or  caseous  foci,  usually  of  the  visceral 
type;  that  is,  they  occur  as  splenic  nodules  and  abscesses,  or  mesenteric 
abscesses.  Sometimes  the  abscesses  are  situated  in  the  regions  of  the 
peripheral  lymph  glands.  Plague  bacilli  are  either  absent  or  very 
scanty  upon  microscopic  examination  in  these  abscesses,  but  they  may 
be  recovered  by  cultural  methods  or  more  surely  by  inoculating  the 
material  into  susceptible  animals.  There  is  no  evidence  to  show  that 
chronic  rat  plague  has  anything  to  do  with  the  recurrence  of  acute  plague 
among  the  rats. 

Eats  may  be  infected  by  the  ingestion  of  infective  material  or  the 
application  of  virulent  plague  bacilli  to  a  mucous  or  cutaneous  surface, 
or  by  subcutaneous  injection  of  the  microorganism.  The  infection  may 
also  be  transferred  from  rat  to  rat  through  the  agency  of  the  flea.  In 
nature  the  mode  of  transference  probably  takes  place  through  all  of 
these  methods,  but  commonly  through  the  flea. 

Contrary  to  the  general  impression,  the  wild  rat  has  a  considerable 
resistance  to  plague  infection.  The  Indian  Plague  Commission  found 
that  59  per  cent,  were  immune  when  inoculated  by  the  subcutaneous 
method  from  the  spleen  of  infected  rats.  A  series  of  experiments  con- 
ducted in  the  Federal  laboratory  in  San  Francisco  also  showed  a  high 
grade  of  immunity,  especially  among  the  large  rats.  About  15  per 
cent,  of  small  rats  and  about  50  per  cent,  of  large  rats  were  found  to 
bo  immune  when  inoculated  with  highly  virulent  material.     The  experi- 


EATS    AXD    OTHER    EODEXTS  273 

ments  demonstrated  that  this  immunity  is  not  acquired  through  a  prior 
attack  of  the  disease,  but  must  be  a  natural  immunity. 

The  natural  subsidence  of  plague  among  rats  in  any  community  is  a^ 
point  about  which  much  more  evidence  must  be  obtained  before  we  can 
speak  with  any  degree  of  authority.  It  may  be  due  to  a  lack  of  suscep- 
tible material,  possibly  to  a  loss  of  virulence  of  the  organism,  but  it 
seems  more  probable  that  it  is  due  to  a  change  in  the  number  or  rela- 
tions of  the  ectoparasites  of  the  rat. 

Rat  Leprosy. — An  infection  resembling  leprosy  occurs  spontaneously 
among  rats  and  bears  a  close  resemblance  to  the  disease  in  man,  but  it 
seems  that  the  rat  leprosy  is  not  communicable  to  man.  For  a  further 
discussion  of  rat  leprosy  see  page  325. 

Trichinosis. — The  three  most  important  hosts  for  the  Trichinella 
spiralis  are  man,  swine,  and  rats.  The  infection  is  spread  by  one  ani- 
mal- eating  the  flesh  of  another.  It  is,  therefore,  evident  that  if  the 
disease  occurred  only  in  hogs  and  man  it  would  soon  die  out.  Eats,  on 
account  of  their  habits,  may  then  be  viewed  as  the  great  reservoir  for 
the  parasite  and  for  the  disease  it  causes.  Hence,  a  well-directed  pub- 
lic health  campaign  against  trichinosis  should  consider  the  eradication 
of  rats,  especially  around  slaughter  houses,  butcher  shops,  hog  pens, 
and  similar  places. 

Trichinosis  is  very  common  among  rats;  they  become  infected  by 
eating  each  other,  by  eating  scraps  of  pork  found  on  the  offal  pile  of 
slaughter  houses,  butcher  shops,  or  in  swill.  Swine  become  infected  by 
eating  rats  and  infected  offal.  Man  becomes  infected  almost  exclusively 
by  eating  pork  or  boar  meat  that  has  not  been  thoroughly  cooked. 

Other  Parasites. — Eats  and  mice  may  harbor  eleven  species  of  inter- 
nal parasites  which  also  occur  in  man.  Several  of  these  are  of  academic 
importance  only.  Those  which  concern  us  principally,  in  addition  to 
the  Trichinella  spiralis,  are  the  Hymenolepis  diminuta  and  Lamblia 
duodenalis.  Eats  also  harbor  the  Cysticercus  cellulosae  and  are  suscep- 
tible to  experimental  infections  with  Trypanosoma  gambiense,  the  cause 
of  sleeping  sickness. 

Lynch  ^  states  that  the  rat  {Mus  norvegicus)  suffers  from  spon- 
taneous amebic  dysentery  similar  to  that  occurring  in  man.  The  rat  is, 
therefore,  a  possible  disseminator  of  dysentery  amebas  pathogenic  for 
man. 

Eats  have  also  been  accused  of  dragging  typhoid  from  the  sewers 
to  our  food.  The  connection  is  close  and  the  possibility  apparent.  A 
recent  outbreak  of  typhoid  fever  in  an  asylum  has,  in  fact,  been  traced 
to  this  source  by  Dr.  Mills. ^ 

Economic  Importance. — The  destruction  of  food,  merchandise,  and 

^Jour.  A.  M.  A.,  LXV,  No.  26,  Dec.  25,  1915,  p.  2232.     K.  M.  Lynch. 
"Brit.  Med,  Jour.,  January  21,  1911. 


274  mSECT-BOENE    DISEASES 

property  by  rats  is  so  great  that  this  alone  would  justify  active  measures 
of  suppression,  even  though  they  were  not  responsible  for  plague,  trichi- 
. nosis,  and  other  infections.  Eats  destroy  grain  while  growing;  invade 
stores,  destroy  flowers,  laces,  silks,  carpets;  eat  fruits,  vegetables,  meat, 
etc.,  in  the  market ;  destroy  by  pollution  ten  times  as  much  as  they  eat ; 
cause  conflagration  by  dragging  matches  into  their  holes;  gnaw  lead 
pipes  and  floors  of  houses;  ruin  artificial  ponds  and  embankments  by 
burrowing;  destroy  eggs  and  young  poultry;  damage  foundations,  floors, 
doors,  piers;  in  short,  they  have  become  the  worst  mammalian  pest 
among  us.  It  is  estimated  that  in  the  United  States  alone  the  losses 
due  to  rat  depredations  vary  from  $35,000,000  to  $50,000,000  an- 
nually. 

Suppression. — The  extermination  of  the  rat  is  hopeless;  they  are 
very  intelligent  and  cautious.  Extermination  seems  a  biological  im- 
possibility, for  killing  off  large  numbers  gives  the  survivors  an  easier 
living.  Millions  of  rats  have  been  killed  in  India,  Japan,  San  Francisco, 
and  other  places  during  the  recent  plague  measures  without  making 
an  appreciable  impress  upon  the  numbers  remaining.  They  may  be 
exterminated  and  kept  out  of  a  limited  area,  such  as  a  ship,  a  granary, 
a  stable,  a  warehouse,  a  market,  or  local  compound.  In  the  well-built 
residential  sections  of  a  city,  with  concrete  walks,  asphalt  streets,  stone 
cellars,  and  few  stables,  there  are  very  few  rats.  In  10  years  of  resi- 
dence in  such  a  district  in  Washington  I  never  saw  or  heard  of  one  in 
the  neighborhood.  Mus  rattus  and  Mus  alexandrinus  are  much  more 
difl&cult  to  suppress  than  Mus  norvegicus;  indeed  it  is  probable  that  we 
have  no  very  satisfactory  method  of  dealing  with  these  rats,  owing  to  the 
fact  that  frequently  they  live  in  trees  and  in  the  fields. 

The  measures  for  the  repression  and  destruction  of  rats  will  be 
considered  under:  (1)  rat-proof  buildings,  (2)  keeping  food  from  rats, 
(3)  natural  enemies,  (4)  traps,  (5)  poisons,  (6)  domestic  animals,  (7) 
shooting,  (8)  fumigation,  and  (9)  bacterial  viruses, 

Eat-proof  Buildings. — This  is  a  measure  of  first  importance  in 
the  fight  against  rats.  Eats  can  only  gain  entrance  to  a  cement  struc- 
ture properly  constructed  through  neglect  or  ignorance.  They  come  in 
through  drain  pipes  if  left  open;  through  doors,  especially  from  alleys; 
and  through  basement  windows.  Once  in,  they  intrench  themselves  in 
out-of-the-way  places,  nest  behind  rubbish,  and  are  difficult  to  dislodge. 
The  lower  parts  of  the  outer  doors  of  public  structures,  such  as  markets 
and  wharves,  should  be  reinforced  with  metal  to  keep  the  rats  from 
gnawing  through.  Basement  windows  should  be  screened  and  doors 
provided  with  springs  to  keep  them  closed.  Screens  or  wire  cloth  to 
keep  out  the  rats  must  be  not  less  than  20  gauge  nor  greater  than  I/2  an 
inch  mesh.  The  special  points  of  ingress  and  egress  of  rats  which  must 
be  guarded  against  besides  basement  windows  and  doors  are  hatches. 


EATS    AND    OTHER   RODENTS  275 

ventilators,  skylights,  unused  chimney  flues,  and  openings  around 
water,  sewer,  gas,  and  steam  pipes,  and  electric  wires. 

Foundation  walls  should  be  laid  without  a  break  around  the  entire 
building  and  should  extend  not  less  than  18  inches  beneath  the  surface 
of  the  surrounding  soil,  and  should  always  be  flush  with  the  under- 
surface  of  the  floor  above.  Floor  joists  should  be  imbedded  in  this  wall 
or  the  spaces  between  the  joists  filled  in  and  completely  closed  up  to  the 
floor  level.  Ground  areas  should  be  concreted  with  a  layer  at  least  3 
inches  in  thickness,  finished  with  a  wearing  surface  of  cement  about 
Y2  an  inch  thick.  The  walls  of  a  wooden  house  should  have  one  foot 
of  concrete  between  the  sheathing  and  lathing.  All  water  and  drain 
pipes  should  be  surrounded  with  cement  where  they  pierce  the  walls.  Rat 
holes  may  be  closed  with  a  mixture  of  cement,  sand,  and  broken  glass, 
or  sharp  bits  of  crockery  and  stone. 

Buildings  may  be  raised  from  the  surface  of  the  ground  on  piers, 
thus  rendering  them  rat-proof.  Cribs  for  grain  in  the  country  can  be 
so  raised  and  further  protected  ^\^th  metal  netting. 

Aside  from  dwellings,  the  chief  refuges  for  rats  in  cities  are  sewers, 
wharves,  stables,  provision  houses,  markets,  out-buildings,  slaughter 
houses,  restaurant  kitchens,  bakery  shops,  candy  factories,  and  uninhab- 
ited structures.  Modern  sewers  are  highways  and  not  nesting  places  for 
rats.  They  find  a  safe  retreat  from  nearly  l,11  enemies  under  wooden 
sidewalks.  In  the  country  it  is  important  to  build  corn  cribs,  barns,  and 
granaries  rat-proof  with  the  liberal  use  of  cement,  iron  sheeting,  or 
galvanized  iron  netting. 

Keeping  Food  feom  Rats. — Well-fed  rats  mature  quickly,  breed 
often,  and  have  large  litters.  A  scarcity  of  food  helps  all  other  sup- 
pressive measures.  Garbage  and  offal  must  be  disposed  of  so  that  rats 
cannot  get  at  such  stuff.  Well-covered  garbage  cans  should  be  required 
and  the  garbage  frequently  removed  and  burned.  To  deposit  it  upon 
the  ground  anywhere  only  invites  and  nourishes  rats  and  other  vermin. 
Slaughter  houses  are  centers  of  rat  propagation.  The  offal  is  best  dis- 
posed of  by  burning.  Care  should  also  be  taken  as  to  the  disposal  of 
remnants  of  lunches  in  office  buildings  and  the  disposal  of  organic  waste 
generally.    Produce  in  provision  stores  may  be  protected  with  wire  cages. 

JSTatukal  Enemies. — The  natural  enemies  of  the  rat  are  the  larger 
hawks,  owls,  snakes,  skunks,  foxes,  coyotes,  weasels,  minks,  dogs,  cats,  and 
ferrets.  The  persistent  killing  off  of  the  carnivorous  birds  and  mammals 
that  prey  upon  rats  has  been  an  important  factor  in  the  increase  of 
these  rodents  in  the  United  States.  Rats  actually  destroy  more  eggs, 
chickens,  and  game  than  all  the  wild  animals  combined. 

Traps. — There  are  many  kinds  of  traps,  such  as  the  guillotine,  spring 
trap,  the  cage  trap,  the  barrel  and  pit  trap.  One  of  the  best  is  the  old- 
fashioned  wire  cage  trap.    The  rats  get  in  but  cannot  get  out.    In  plac- 


276  INSECT-BORNE    DISEASES 

ing  the  trap  it  is  advisable  to  leave  a  rat  in  as  a  decoy.  The  trap  should 
be  placed  along  runways,  or  the  entrance  to  the  trap  may  be  arranged  so 
that  the  rats  first  have  to  go  through  a  pipe,  as  they  like  to  explore 
dark  passages.  It  requires  ingenuity  to  successfully  trap  rats.  They 
are  very  wary  and  avoid  man-smell.  To  guard  against  this  the  traps 
may  be  burned  and  then  smeared  with  the  bait,  always  handling  them 
with  tongs  or  properly  prepared  gloves.  Cheese,  bacon,  grain,  and  also 
meat,  vegetables,  or  bread  are  the  best  baits. 

Poisons. — Poisons  are  objectionable  in  dwellings,  owing  to  the  odor 
of  the  dead  rats.  They  are  of  service  in  granaries,  stables,  wharves, 
storage  depots,  garbage  dumps  and  similar  places  where  rat-proofing  is 
difficult  or  too  expensive.  Most  rat  poisons  are  dangerous  to  children 
as  well  as  to  chickens  and  other  domestic  animals,  and,  therefore,  the 
greatest  care  must  be  exercised  in  their  use.  It  requires  experience  in 
laying  out  poisons;  the  old  rats  are  very  smart  and  will  refuse  the  bait 
unless  artfully  concealed  and  judiciously  placed. 

The  principal  poisons  used  for  rats  are  barium  carbonate,  strychnin, 
arsenic,  and  phosphorus.  In  several  states  the  law  requires  that  notice 
of  intention  to  lay  poison  must  be  given  to  persons  living  in  the  neigh- 
borhood. Poisons  for  rats  should  never  be  placed  in  open  or  unsheltered 
places.  In  buildings  and  yards  occupied  by  poultry  the  following  pro- 
cedure is  recommended :  Two  wooden  boxes  should  be  used,  one  con- 
siderably larger  than  the  other,  and  each  having  two  or  more  holes  in  the 
sides  large  enough  to  admit  rats.  The  poisoned  bait  should  be  placed 
in  the  bottom  and  near  the  middle  of  the  smaller  box,  and  the  larger 
box  should  then  be  inverted  over  the  other.  Eats  thus  have  free  access 
to  the  bait,  but  fowls  are  excluded. 

The  cheapest  and  most  effective  poison  is  barium  carbonate.  This 
may  be  made  into  a  dough,  with  four  parts  of  meal  or  flour  to  one  part 
of  barium  carbonate.  A  good  plan  is  to  spread  the  barium  carbonate 
upon  fish,  on  toasted  bread  (moistened),  or  upon  ordinary  bread  and 
butter. 

Strychnin  is  effective  and  may  be  used  by  inserting  the  dry  crystals 
in  a  piece  of  meat,  cheese,  or  sausage,  which  is  placed  in  the  runways. 

Arsenic  is  popular;  the  powdered  white  arsenic  (arsenious  acid) 
may  be  used  as  described  for  strychnin  or  barium;  or  a  stiff  dough 
may  be  made  by  mixing  twelve  parts  by  weight  of  com  meal  and  one 
part  of  arsenic  with  whites  of  egg.  An  old  English  formula  is  one 
pound  of  oatmeal,  one  pound  of  brown  sugar,  and  a  spoonful  of  ar- 
senic. 

Phosphorus  is  an  effective  and  attractive  bait.  The  yellow  phosphorus 
in  the  proportion  of  one  to  four  per  cent,  may  be  mixed  with  glucose 
or  other  suitable  material.  The  use  of  phosphorus  is  very  dangerous  on 
account  of  fire.    Eats  poisoned  with  phosphorus  may  die  on  the  premises 


EATS  AND  OTHER  RODENTS  277 

and  decompose,  contrary  to  the  statements  sometimes  made  in  the  adver- 
tisements. 

The  following  formula  is  recommended  as  a  poisonous  bait  for  rats, 
mice,  squirrels,  etc. : 

Strychnin   1  oz. 

Cyanid  of  potassium 3  oz. 

Eggs    1  doz. 

Honey   1  pint 

Wheat  or  barley 30  lbs. 

Stir  eggs  well,  then  mix  in  honey  and  again  stir.  Then  put  in  dry 
powdered  strychnin  and  cyanid  and  stir  until  well  mixed.  Put  wheat 
in  large  box  or  can  and  pour  in  the  mixture  of  poison  and  stir  until 
it  is  well  distributed  over  the  wheat.  Stir  two  or  three  times  during 
twenty-four  hours,  then  spread  out  and  dry.  Before  putting  it  out  for 
squirrels  add  oil  of  rhodium,  1  dram. 

Poisons  and  traps  reduce  the  number  of  rats  but  do  not  eliminate 
them.  Poisons  and  traps  find  their  greatest  usefulness  in  ridding  large 
rat-proof  structures  of  contained  rats.  Starving  rats  by  keeping  food 
from  them  is  one  of  the  best  methods  of  suppression. 

Domestic  Animals. — A  well-trained  dog  may  be  relied  upon  to 
keep  the  farm  premises  reasonably  free  of  rats.  Small  Irish,  Scotch, 
and  fox  terriers  make  the  best  ratters;  the  ordinary  cur  and  the  larger 
breeds  of  dogs  seldom  develop  the  necessary  qualities  for  ratters. 

However  valuable  cats  may  be  as  mousers,  few  of  them  care  to 
catch  rats.  The  ordinary  house  cat  is  too  well  fed  and  too  lazy  to  un- 
dertake the  capture  of  an  animal  as  formidable  as  the  brown  rat.  Koch 
has  advised  the  breeding  and  distribution  of  cats  capable  and  willing  to 
attack  rats. 

Shooting. — Many  rats  may  be  shot  as  they  come  out  to  forage  about 
sundown.  This  method  is  particularly  effective  in  a  large  building 
which  is  suddenly  overrun  with  the  rodents.  The  shooting  of  a  number 
of  them  upon  two  or  three  successive  nights  discourages  the  remainder, 
who  leave  for  some  other  happier  hunting  ground. 

Fumigation. — Rats  may  be  killed  with  certainty  in  any  inclosed 
structure  by  the  use  of  sulphur  dioxid,  carbon  bisulphid,  hydrocyanic 
acid  gas,  or  carbon  monoxid.  The  methods  of  evolving  these  substances 
have  been  described  in  Section  XII.  Sulphur  dioxid  is  particularly 
useful  to  destroy  rats  on  board  ships,  in  cellars,  stables,  sewers,  and 
places  where  they  abound  and  which  are  not  injured  by  the  corrosive 
action  of  the  sulphur  fumes.  Enormous  numbers  of  rats  are  frequently 
killed  when  ships  are  fumigated  with  sulphur  dioxid.  I  have  seen  buck- 
ets full  thrown  overboard  from  comparatively   small   vessels.      Hobdy 


278  INSECT-BOENE    DISEASES 

counted  310  on  a  lumber-carrying  schooner  of  only  260  tons  burden. 
The  S.S.  Minnehaha,  a  new  vessel  only  nine  months  in  commission 
fumigated  in  London  in  May,  1901,  yielded  a  bag  of  1,700  rats. 

For  the  destruction  of  rats  upon  vessels  the  sulphur  dioxid  may  be 
produced  by  the  pot  method,  if  the  hold  is  empty,  or  may  be  generated 
in  a  Kinyoun-Francis  or  a  Clayton  furnace,  or  may  be  liberated  from 
its  compressed  liquefied  state.  No  less  than  three  pounds  of  sulphur 
should  be  burned  for  each  1,000  cubic  feet  of  space,  and  the  exposure 
should  not  be  less  than  5  hours  (see  page  1142). 

Carbon  Monoxid. — Carbon  monoxid  is  an  exceedingly  poisonous  gas. 
From  the  fact  that  it  has  no  odor  it  is  even  more  hazardous  in  practice 
than  hydrocyanic  acid.  Carbon  monoxid  is  fatal  to  all  forms  of  mam- 
malian life,  but  has  no  germicidal  properties  whatever.  It  has  been 
used  in  Hamburg  ^  and  other  ports  for  the  destruction  of  rats  on  ships. 

Carbon  monoxid  is  a  colorless,  odorless  gas,  lighter  than  air.  It 
forms  a  stable  compound  with  the  hemoglobin  of  the  blood — carbon 
monoxid-hemoglobin.  For  the  toxic  action  of  this  gas  and  its  other 
properties  see  page  721.  The  particular  advantages  of  carbon  monoxid 
for  the  destruction  of  rats  on  board  ship  are  that  it  may  be  generated 
cheaply,  is  quickly  effective,  and  does  no  injury  to  cargo  or  vessel.  The 
disadvantages  are  that  it  is  poisonous  and  inflammable.  The  addition 
of  a  little  sulphur  dioxid  to  the  gas  makes  its  presence  known  and  tends 
to  prevent  accidents.  After  exposure  the  hold  must  be  thoroughly  ven- 
tilated, and  it  is  customary  to  lower  a  mouse  in  a  cage  for  10  minutes 
to  be  sure  that  it  is  safe  for  a  man  to  enter.  Divers'  helmets  should 
also  be  kept  in  readiness  so  that  the  hold  may  be  entered  in  case  of  need. 

A  gas  generator  has  been  made  by  Pintsch  which  furnishes  a  mix- 
ture consisting  of  CO,  5  per  cent.,  CO 2,  18  per  cent.,  N",  77  per  cent. 
These  gases  are  generated  by  the  incomplete  combustion  of  coke.  The 
mixture  of  gases  is  pumped  into  the  hold  of  the  vessel  or  other  com- 
partments where  it  is  desired.  The  hold  should  be  kept  tightly  closed 
from  7  to  8  hours.    Funnel  gases  are  also  serviceable. 

The  Bacterial  Eat  Viruses. — Eats  are  notoriously  resistant  to 
bacterial  infection.^  Even  plague  usually  fails  markedly  to  diminish 
their  prevalence.  An  epizootic  of  bacterial  nature,  therefore,  cannot  be 
classed  with  the  natural  enemies  of  the  rat.  We  are  not  surprised,  then, 
to  learn  that  the  bacterial  rat  viruses  have  signally  failed  to  accomplish 
their  mission. 

These  bacterial  viruses  belong  to  the  colon-typhoid  group  of  organ- 
isms.    They  are  either  identical  with  or  closely  related  to  the  original 

*Nocht  and  Giemsa:  Arbeiten  a.  d.  kaiserlichen  Gesundheitsampte,  Bd.  20, 
Ersten  Heft,  1904,  p.  91. 

*  "The  InefRciency  of  Bacterial  Viruses  in  the  Extermination  of  Rats,"  M.  J. 
Rosenau.  "The  Rat  and  Its  Relation  to  the  Public  Health,"  Bulletin  of  the 
P.  H.  &  M.  H.  S.,  1910. 


EATS  AND  OTHEK  EODENTS  279 

bacillus  of  mouse  typhoid  (B.  typhi  murium)  discovered  by  Loeffler,  or 
the  paratyphoid  bacillus,  type  B,  which  is  frequently  the  cause  of  meat 
poisoning,  or  the  Bwcillu^  erderitidis  of  Gaertner,  which  has  been  asso- 
ciated with  gastro-intestinal  disorders. 

The  claim  that  these  rat  viruses  are  harmless  to  man  needs  revision, 
in  view  of  the  instances  of  sickness  and  death  reported  by  various  ob- 
servers. The  pathogenicity  for  man  depends  upon  the  virulence  of  the 
culture,  the  amount  ingested,  the  nature  of  the  medium  in  which  it 
grows,  and  many  other  factors. 

Danysz  virus  {B.  typhi  murium)  is  pathogenic  for  rats  under  labora- 
tory conditions,  but  has  feeble  powers  of  propagating  itself  from  rat  to 
rat.  It  rapidly  loses  its  virulence,  especially  when  exposed  to  light  and 
air.  The  result  depends  largely  upon  the  amount  ingested.  The  other 
viruses  have  proven  even  less  satisfactory. 

Under  natural  conditions  these  rat  viruses  may  be  likened  to  a 
chemical  poison,  with  the  great  disadvantage  that  they  rapidly  lose  their 
virulence  and  are  comparatively  expensive.  They  also  have  the  further 
disadvantage  that  chemical  poisons  do  not  possess  of  rendering  animals 
immune  by  the  ingestion  of  amounts  that  are  insufficient  to  kill  or  by 
the  ingestion  of  cultures  that  have  lost  their  virulence. 

Squirrels. — In  August,  1903,  a  blacksmith  died  of  plague  probably 
contracted  from  a  squirrel  in  Contra  Costa  County,  California.  In 
1904  Currie  demonstrated  the  susceptibility  of  the  ground  squirrel  to 
bubonic  plague.  In  1908  McCoy  and  Wherry  discovered  natural  plague 
in  ground  squirrels.  It  was  then  learned  that  thousands  of  squirrels 
had  died  of  some  disease  during  1904,  1905,  and  1906.  This  epizootic 
was  doubtless  plague.  It  is  now  realized  that  plague  has  become  en- 
demic in  California,  in  the  squirrel.  It  is  also  believed  that  the  disease 
has  been  kept  alive  in  the  endemic  foci  of  Tibet  in  another  rodent,  the 
marmot  (Arctomys  hohac).  The  eradication  of  plague  must,  therefore, 
consider  these  and  perhaps  other  susceptible  wild  animals. 

California  is  overrun  with  three  species  of  ground  squirrels.  The 
commonest  is  the  Citellus  heecheyi.  They  live  in  colonies  in  burrows 
or  warrens.  The  booby  owl  is  a  frequent  companion  occupying  the  same 
burrow,  and  they  probably  spread  the  infection  by  carrying  fleas.  Squir- 
rels become  infected  through  fleas  from  each  other  and  from  rats.  The 
squirrel  flea  (Ceratophyllus  acutus)  attacks  man  just  as  the  rat  flea 
does.  The  infection  may  also  be  conveyed  to  man  through  squirrel  bites, 
as  in  the  case  of  the  child  in  Los  Angeles  studied  by  Stimson.  Squir- 
rels make  good  food  for  man,  but  since  the  danger  has  been  realized 
the  shooting  or  trapping  of  them  for  food  purposes  is  now  forbidden 
in  California. 

Plague  in  the  squirrel  may  be  recognized  ^  by  the  gross  anatomical 

^  McCoy:     Jour,  of  Infect.  Dis.,  Nov.  26,  1909,  Vol.  V,  No.  5. 


280  INSECT-BOKNE    DISEASES 

lesions  in  the  lymphatic  glandS;,  the  liver,  and  lungs.  The  pneumonic 
form  of  the  disease  is  common  in  the  squirrel.  Many  cases  are  subacute 
or  chronic.  Smear  preparations  from  squirrels  dead  of  plague  are  fre- 
quently negative  for  plague-like  bacilli.  The  diagnosis  may,  therefore, 
be  made  more  surely  by  animal  experimentation.  Subcutaneous  inocula- 
tion is  surer  than  the  cutaneous  method,  as  the  latter  often  fails  on 
account  of  the  comparatively  few  plague  bacilli  present  in  squirrel 
lesions. 

Squirrels  may  be  destroyed  by  various  means.  One  of  the  most 
successful  is  to  saturate  cotton  waste  the  size  of  an  orange  with  carbon 
bisulphid  and  place  it  in  the  warren;  then  close  the  opening  with  wet 
clay.  Officers  of  the  Public  Health  Service  working  in  California  have 
devised  an  apparatus  for  vaporizing  carbon  bisulphid  and  pumping  the 
gas  into  the  burrows.  This  method  is  reported  to  be  much  more  suc- 
cessful than  any  other  that  has  been  employed.  Poisoned  bait,  such  as 
strychnin,  phosphorus,  or  cyanid  of  potassium,  is  effective.  Traps  are 
not  very  successful,  as  the  squirrel  is  wary.  Natural  enemies,  such  as  the 
coyote,  wolf,  badger,  skunk,  mountain  lion,  the  cobra  snake,  and  red- 
tailed  hawk  should  be  encouraged.^ 

PLAGUE 

In  considering  the  prevention  of  plague  it  is  necessary  to  recog- 
nize that  the  different  types  of  the  disease  are  spread  in  different  ways. 
At  least  three  clinical  types  are  now  recognized:  (1)  bubonic,  (2)  pneu- 
monic, and  (3)  septicemic.^  In  the  bubonic  and  septicemic  types  of 
the  disease  the  plague  bacillus  is  locked  up  in  the  glands,  blood,  and  other 
tissues  and  organs  of  the  body,  and  are  not  eliminated  in  the  usual  ex- 
cretions. These  forms  of  the  disease  are,  therefore,  not  "contagious," 
but  are  spread  mainly  through  the  agency  of  the  flea.  On  the  other 
hand,  in  the  pneumonic  type  of  the  disease  plague  bacilli  are  contained 
in  enormous  numbers  in  the  sputum.  The  disease  is  frequently  trans- 
mitted directly  by  close  association  with  a  patient  having  plague  pneu- 
monia. The  pneumonic  type  of  the  disease  does  not  necessarily  follow 
when  the  infection  is  taken  into  the  system  through  the  respiratory 
channel ;  on  the  other  hand,  it  may  result  from  infection  through  a  flea 
bite. 

Pneumonic  plague  may  assume  epidemic  proportions,  especially  in 

^In  this  chapter  material  has  been  freely  drawn  from  "The  Rat  and  Its 
Relation  to  the  Public  Health,"  Public  Health  and  Marine  Hospital  Service,  1910, 
particularly  articles  by  Lantz,  McCoy,  Brinckerhoflf,  Banks,  Stiles,  Rucker,  Creel, 
Holdy,  Kerr,  and  Rosenau.  This  book  may  be  obtained  by  addressing  the  Surgeon- 
General  or  the  Superintendent  of  Public  Documents,  Washington,  D.  C. 

^  Occasionally  other  varieties  occur  in  which  the  chief  manifestations  are  in 
the  skin  and  subcutaneous  tissues,  or  in  the  intestines,  causing  diarrhea.  In  the 
latter  case  the  infection  is  excreted  in  the  feces. 


EATS  AND  OTHER  EODENTS  281 

the  cold  weather  and  under  circumstances  where  people  come  in  close 
association.  This  was  the  case  in  the  Manchurian  epidemic  of  1910-1911 
which  occurred  during  the  winter  and  was  one  of  the  most  virulent 
epidemics  of  modern  times,  the  mortality  being  over  90  per  cent. 

Teague  and  Barber  ^  explain  the  rapid  spread  of  pneumonic  plague  in 
Manchuria  and  the  failure  of  this  type  of  the  disease  to  spread  to  India 
upon  the  assumption  that  in  the  warm  temperatures  of  Indian  the  drop- 
lets quickly  dry  and  the  plague  bacilli  soon  die,  whereas  in  Manchuria 
the  temperature  and  humidity  do  not  favor  evaporation  and  hence  the 
droplets  of  sputum  persist  longer  in  the  cold  atmosphere  and  the  plague 
bacilli  remain  alive  longer. 

The  Bacillus  pestis  (Yersin,  1894)  has  more  than  fulfilled  Koch's 
laws.  Several  accidents  in  which  pure  cultures  have  been  inoculated 
into  man,  producing  all  the  symptoms  and  lesions  of  the  disease,  have 
added  to  the  proof  that  this  organism  is  the  cause  of  plague  (Vienna, 
1898,  Ann  Arbor,  1902,  and  also  in  laboratories  in  Russia,  Berlin,  and 
Japan).  The  plague  bacillus  is  comparatively  easy  to  isolate  and  grows 
readily  on  artificial  culture  media,  and  has  characteristics  that  readily 
distinguish  it  from  all  other  species.  It  is  a  short  rod  with  rounded  ends, 
not  motile,  decolorized  by  Gram's  method,  and  grows  well  at  room  tem- 
perature though  less  luxuriantly  than  at  37°  C. 

Recognition  of  the  plague  bacillus  rests  upon  the  following  charac- 
teristics: (1)  Curious  involution  forms  upon  salt  agar  within  24  hours; 
(2)  stalactite  growth  in  liquid  media;  (3)  characteristic  lesions  pro- 
duced by  experimental  plague  in  guinea-pigs,  rabbits,  rats,  etc.  Kolle's 
method  consists  in  rubbing  the  material  containing  the  plague  bacillus 
upon  a  shaved  area  of  the  skin  of  a  guinea-pig.  The  plague  bacilli  pene- 
trate the  skin,  leaving  other  organisms  behind.  The  skin  of  the  guinea- 
pig  thus  acts  as  a  differential  filter;  (4)  the  final  test  of  the  identity  of 
the  plague  bacillus  is  the  fact  that  its  pathogenicity  may  be  neutralized 
by  the  use  of  antiplague  serum. 

The  Bacillus  pestis  does  not  live  a  saprophytic  existence  in  nature. 
It  is  readily  killed  by  drying,  sunlight,  heat,  and  the  usual  germicides. 
The  organism  does  not  live  long  in  the  soil  or  upon  the  floors  of  houses, 
as  was  once  commonly  supposed.  There  is,  therefore,  comparatively 
little  danger  from  these  sources. 

Immunity. — One  attack  of  plague  usually  protects  for  life.  Occa- 
sionally second  attacks  are  noted  in  the  same  person.  In  such  cases 
the  second  attack  is  usually  mild.  This  is  an  old  observation  and  led 
to  the  employment  of  persons  with  a  plague  history  or  a  plague  scar 
in  hospitals  and  laboratories. 

^  Teague,  0. :  "A  Further  Note  on  the  Influence  of  Atmospheric  Temperature 
on  the  Spread  of  Pneumonic  Plague,"  Philippine  Jour.,  Sc,  B.,  Tropical  Med., 
1913.  VIII,  241. 


283  INSECT-BORNE    DISEASES 

Artificial  immunity  of  either  an  active  or  passive  nature  may  be 
acquired  by  various  procedures.  The  passive  immunity  produced  by 
the  injection  of  antiplague  serum  lasts  only  about  three  to  four  weeks. 
The  active  immunity  produced  by  vaccination  of  cultures  may  be  de- 
pended upon  for  about  six  months. 

Haffkine's  prophylactic  consists  of  a  killed  culture  of  the  plague 
bacillus,  which  is  injected  subcutaneously.  Haffkine  used  a  bouillon 
culture,  six  weeks  old,  grown  at  25-30°  C.  and  killed  at  65°  C,  for 
one  hour.  One-half  of  one  per  cent,  of  phenol  is  then  added.  From 
2  to  3.5  c.  c.  (this  was  later  increased  to  20  c.  c.)  of  this  vaccine  are  in- 
jected subcutaneously.  Ten  days  later  a  second  injection  of  a  still  larger 
amount  is  given. 

In  twelve  districts  in  India  224,228  persons  were  inoculated  with 
Haffkine's  prophylactic.  Of  these  3,399  took  the  disease.  Of  639,600 
not  inoculated  in  the  same  districts  49,430  were  attacked.  C.  J.  Martin 
concludes  that  the  chances  of  subsequent  infection  are  reduced,  four-fifths, 
and  the  chances  of  recovery  are  2.5  times  as  great  as  in  the  cases  of  the 
non-vaccinated. 

The  German  Plague  Commission  prepared  their  prophylactic  vac- 
cine from  a  fresh  virulent  agar  culture,  suspending  the  bacilli  in  salt 
solution  or  bouillon.  The  organisms  are  killed  at  65°  C.  for  one  to 
two  hours,  and  0.5  per  cent,  phenol  added.  The  amount  injected  rep- 
resents one  agar  culture. 

Lustig  and  Galeoti  extract  the  immunizing  substance  from  the  bac- 
terial cell  (endotoxin)  with  weak  potassium  hydroxid.  This  nucleo- 
protein  is  collected  and  dried,  and  thus  permits  of  exact  dosage.  The 
amount  injected  is  two  to  three  milligrams  of  the  dry  extract  dis- 
solved in  water. 

Terni  and  Bandi  recommend  the  peritoneal  exudate  of  plague- 
infected  guinea-pigs,  sterilized  fractionally  at  50°  C,  and  the  addition 
of  0.5  per  cent,  of  phenol,  0.25  per  cent,  sodium  carbonate,  and  0.75 
per  cent,  sodium  chlorid. 

Shiga  prefers  a  combined  active  and  passive  immunity  produced 
with  killed  cultures  and  antipest  serum,  because  this  mixed  immu- 
nizing process  has  the  advantage  of  producing  milder  reactions. 

Kolle  and  also  Strong  started  out  from  the  principle  that  a  much 
higher  degree  of  immunity  is  produced  by  living  microorganisms  than 
dead  ones,  and  recommend  the  use  of  live  attenuated  cultures.  Strong 
has  a  strain,  an  entire  agar  culture  of  which  may  be  injected  into  man 
without  harm.  In  Manila  42  persons  were  given  a  preventive  inocula- 
tion with  this  culture. 

The  reactions  which  follow  vaccination  with  a  plague  culture, 
whether  alive  or  dead,  are  sometimes  marked.  The  symptoms  consist 
of  a  rise  in  temperature  to  39°  C,  malaise,  depression,  and  headache, 


EATS  AND  OTHER  RODENTS  283 

and  swelling  and  pain  at  the  site  of  the  inoculation.  The  symptoms 
usually  pass  away  in  24  to  48  hours. 

The  production  of  an  active  acquired  immunity  has  a  distinct  prac- 
tical usefulness  in  the  prevention  of  the  disease,  although  it  cannot  take 
the  place  of  rat  and  flea  eradication.  It  has  been  used  on  a  large 
scale  by  Haffkine  in  India,  and  to  a  lesser  extent  by  others  in  many 
parts  of  the  world  during  the  recent  plague  pandemic.  Those  who 
get  plague  after  Haffkinization  usually  have  a  mild  form  of  the  dis- 
ease, which,  in  the  experience  in  India,  rarely  results  in  death.  It  is 
of  first  importance  in  protecting  small  communities,  on  shipboard,  in 
camps  and  barracks,  at  quarantine  stations,  in  plague  laboratories,  among 
rat  brigades,  as  well  as  for  physicians,  nurses,  and  others  who  are  ex- 
posed. 

Yersin's  serum  is  obtained  from  a  horse  that  has  received  repeated 
injections  of  plague  cultures;  at  first  killed  plague  cultures,  afterward 
living  bacilli,  are  used.  At  most  this  antitoxic  serum  is  weak,  and, 
while  it  has  a  certain  amount  of  protective  properties,  it  has  slight 
curative  power.  Very  large  quantities  must  be  administered  early  in 
the  disease  to  obtain  any  effect  at  all.  The  protection  lasts  only  a  few 
weeks,  "three  to  four  at  most,  and  is,  therefore,  of  limited  practical  use. 

Endemic  Foci. — There  are  four  historic  endemic  foci  in  which  plague 
has  slumbered  for  ages.  One  is  on  the  eastern  slope  of  the  Himalayas, 
in  the  province  of  Yiinnan.  The  great  epidemic  in  Hongkong  in  1894 
came  from  this  center.  A  second  endemic  focus  near,  and  perhaps  con- 
nected with  the  first  is  on  the  western  slope  of  the  Himalayas.  From 
here  the  infection  was  carried  to  Bombay  in  1896,  where  it  still  prevails. 
A  third  plague  focus  exists  from  about  the  center  of  Arabia  to  near  Meso- 
potamia. From  here  the  infection  was  dragged  to  Samarkand,  the  Black 
Sea,  and  Persia;  The  fourth  endemic  area  was  discovered  by  Koch  in 
1898  in  the  interior  of  Africa,  near  the  source  of  the  White  Nile  in 
Uganda.  We  must  now  add  to  this  a  fifth  endemic  focus,  for  plague  has 
obtained  a  foothold  in  California  in  the  ground  squirrels,  which  will 
take  years  of  well-directed  energy  to  control.  The  disease  has  caused 
dreadful  havoc  in  India  since  1892.  In  1907  over  one  million  persons 
died  of  plague  in  that  country. 

Management  of  a  Plague  Epidemic. — The  handling  of  a  plague  epi- 
demic is  conducted  along  two  definite  lines  of  activity.  One  is  to  find 
and  care  for  the  human  cases,  the  other  consists  in  a  warfare  against 
rats.  The  organization  and  general  management  of  a  plague  campaign 
do  not  differ  radically  from  similar  work  in  other  epidemics  (see  page 
368).  Cases  of  the  disease  must  be  sought  for  and  early  diagnosis  con- 
firmed; all  deaths  from  no  matter  what  cause  must  be  investigated, 
and  the  body  examined  by  an  expert  before  burial  is  permitted.  A 
bacteriological  laboratory  is  a  sine  qua  non.    Cases  of  the  disease  should 


284  INSECT-BORNE    DISEASES 

be  isolated  and  the  usual  disinfection  of  excreta  and  surroundings  exer- 
cised. Particular  care  must  be  taken  that  the  isolation  wards  are  vermin- 
free.  The  place  from  which  the  case  is  removed  should  be  given  a  pre- 
liminary disinfection  with  sulphur  dioxid  or  other  substance  that  may  be 
depended  upon  to  kill  rats  and  fleas,  and  a  search  made  in  the  neighbor- 
hood for  secondary  cases  both  in  man  and  rodents. 

The  campaign  against  the  rat  is  expensive  and  difficult,  but  must 
be  vigorously  prosecuted  to  insure  success.  The  rat  warfare  may  be 
briefly  summarized  as  a  simultaneous  attack  upon  the  habitation  and 
food  supply  of  the  rat;  the  destruction  of  rat  burrows  and  nesting 
places ;  the  separation  of  the  rat  from  his  food  supply  by  concreting  and 
screening  such  places  as  stables,  warehouses,  markets,  restaurants,  etc.; 
the  prevention  of  the  entry  of  the  rat  into  human  habitations  by  the 
use  of  concrete,  wire  netting,  or  other  barriers ;  and  the  use  of  poisons, 
traps,  etc.  For  further  consideration  concerning  rats  and  their  eradi- 
cation see  page  267.  All  the  rats  that  are  caught  in  traps  or  found 
dead  are  brought  to  the  bacteriological  laboratory,  where  they  are  ex- 
amined and  careful  records  kept  concerning  the  species,  the  location, 
the  place  where  the  rat  was  caught,  the  character  of  the  infection,  etc. 
As  it  is  a  hopeless  task  to  exterminate  rats  from  a  large  city,  Heiser 
has  proposed  a  practical  plan  which  proved  effective  in  Manila.  A 
list  of  the  places  in  which  the  plague-infected  rats  were  found  was 
made.  Each  was  regarded  as  a  center  of  infection.  Eadiating  lines, 
usually  five  in  number,  were  prolonged  from  this  center,  evenly  placed 
like  the  spokes  of  a  wheel.  Eats  were  caught  along  these  lines  and 
examined.  Plague  rats  were  seldom  found  more  than  a  few  blocks 
away.  The  furthermost  points  at  which  the  infected  rats  were  found 
were  then  connected  with  a  line,  as  is  roughly  shown  in  the  diagram, 
Figs.  44  and  45.  The  place  inclosed  by  the  dotted  line  was  regarded  as  a 
section  of  infection.  The  entire  rat-catching  force  was  then  concen- 
trated along  the  border  of  the  infected  section,  that  is,  along  the  dotted 
line.  They  then  commenced  to  move  toward  the  center,  catching  the 
rats  as  they  closed  in.  Behind  them  ratproofing  was  carried  out.  One 
section  after  another  was  treated  in  this  way,  until  they  had  all  been 
wiped  out.  Once  weekly  thereafter  rats  were  caught  in  the  previously 
infected  sections  and  at  other  places,  especially  those  which  had  been 
infected  in  years  gone  by.  Since  the  above  system  was  adopted  plague 
has  disappeared  in  the  city  of  Manila,  and  at  a  cost  of  only  a  small 
fraction  of  that  of  a  general  rat  extermination  campaign.  A  campaign 
along  these  same  general  lines  has  also  been  successful  in  New  Orleans. 

Quarantine. — Plague  infection  is  frequently  carried  over  seas  in 
vessels.  When  this  happens  it  is  more  apt  to  be  due  to  the  disease  in 
the  rat  than  man.  Maritime  quarantine,  therefore,  finds  its  greatest 
justification  in  keeping  out  plague.     To  be  successful,  measures  must 


EATS    AND    OTHER    RODENTS 


285 


be  directed  almost  entirely  against  the  rat,  although  a  keen  eye  must 
be  kept  on  the  lookout  for  mild  cases  known  as  Pestis  minor,  or  walk- 
ing plague.  Rats  may  be  kept  down  on  board  a  vessel  by  the  frequent 
use  of  sulphur  dioxid.  All  vessels  trading  with  a  plague-infected  port 
should  have  each  cargo  compartment  fumigated  with  this  gas,  at  least 
when  it  is  empty,  at  the  port  of  departure.  The  vessel  must  be  again 
fumigated  with  sulphur  dioxid  on  arrival.  Both  at  the  infected  port 
and  at  the  port  of  arrival  care  must  be  taken  to  prevent  the  ingress 


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and  egress  of  rats.  The  period  of  detention  of  the  personnel  for  a 
plague  ship  is  seven  days.  For  further  details  concerning  quarantine 
see  page  371. 

Prevention — Summary. — The  principles  and  many  of  the  details  for 
the  prevention  of  plague  have  been  stated  in  the  foregoing  pages,  and 
need  not  be  repeated. 

Personal  prophylaxis  consists  in  avoiding  the  infected  regions  and 
guarding  against  flea  bites.  Physicians  and  nurses  should  remember 
that  the  pneumonic  form  of  the  disease  is  highly  "contagious"  in  the 
ordinary  sense  of  the  term.  Attendants  and  persons  who  come  in  con- 
tact with  such  cases  may  protect  themselves  with  Haffkine's  prophylac- 


286 


INSECT-BOENB    DISEASES 


tic.  Individual  measures  to  guard  against  droplet  infection,  such  as  the 
wearing  of  masks  or  veils  of  cheesecloth,  may  be  resorted  to.  The  bubonic 
and  septicemic  forms  of  the  disease  are  not,  as  a  rule,  directly  com- 
municable, and,  therefore,  the  preventive  measures  recommended  for 
typhoid  fever  are  effective. 

The  ordinary  germicidal  solutions,  such  as  bichlorid  of  mercury, 
1-1,000,  carbolic  acid,  3I/2  per  cent.,  formalin,  10  per  cent.,  are  effec- 
tive against  the  Bacillus  pestis.     Of  the  gaseous  disinfectants  sulphur 


Fig.  45. — Isolated  Plague-infested  Center,  Manila,  P.  I. 

dioxid  is  preferred,  because  it  not  only  kills  the  frail  plague  bacillus, 
but  also  destroys  rats,  fleas,  etc. 

Cases  of  plague  should  be  isolated  in  a  well-screened  room  other- 
wise free  of  insects.  Fabrics  and  other  objects  which  become  contam- 
inated with  the  discharges  should  be  thoroughly  disinfected  by  proper 
methods. 

It  is  important  to  have  prompt  reports  of  all  cases  of  suspected 
plague,  and  the  diagnosis  must  be  confirmed  by  bacteriological  meth- 
ods. In  all  plague  centers  there  should  be  a  special  hospital  and  also 
a  laboratory  where  diagnostic  work  may  be  carried  on;  this  is  an  es- 
sential part  of  the  equipment  for  a  successful  campaign.  A  traveling 
laboratory  organized  like  a  flying  squadron  for  quick  service  should 
be  provided  to  furnish  this  service  wherever  it  may  be  demanded. 


TICKS  287 

The  prevention  of  plague,  after  all,  is  reduced  to  warfare  against 
rats  and  fleas.  This  has  been  fully  discussed.  All  seaport  towns  hav- 
ing communication  with  plague  countries  should  examine  rats  caught 
about  the  wharves  and  other  places  for  plague.  This,  in  fact,  should 
be  one  of  the  routine  duties  of  the  port  sanitary  authorities.  Plague 
may  slumber  in  the  rats  for  years  before  human  cases  occur.  Other 
preventive  measures  are  obvious  from  the  nature  of  the  infection  and 
its  mode  of  transmission,  or  have  already  been  stated  in  the  preceding 
pages. 

TICKS 

Ticks  belong  to  the  family  Ixodidae,  and  the  diseases  which  they 
transmit  are  known  as  ixodiasis.  Quite  a  number  of  different  species 
are  known  to  attack  man. 

Ticks,  or  wood  lice,  are  not  true  Insecta,  but  belong  to  the  acarines 
which  include  the  mites,  and  are  closely  allied  to  spiders  and  itchmites 
(scabies).  Ticks  have  an  unsegmented  body  with  eight  legs  in  the 
adult  stage  and  six  legs  in  the  larval  stage.  In  some  of  their  habits 
they  resemble  bedbugs.  So  far  as  is  known,  they  take  no  vegetable 
food,  but  live  on  blood.  Ticks  are  ectoparasites  of  man  and  many  ani- 
mals. They  frequently  hang  tenaciously  to  the  skin,  in  which  they 
partly  bury  themselves.  If  covered  with  oil  or  vaselin,  thus  clos- 
ing their  breathing  pores  situated  behind  the  fourth  pair  of  legs,  they 
may  be  induced  to  release  their  hold.  If  pulled  off  roughly  the  head 
(capitulum)  is  likely  to  break  off  and  remain  in  the  skin.  Sulphur 
in  some  form  is  useful  to  destroy  ticks  in  the  adult  stage.  Sulphur 
ointment  is  particularly  obnoxious  to  this  group  of  parasites.  Ar- 
senic and  crude  oil  also  act  as  poisons  to  the  tick,  and  may  be  used 
by  local  application. 

The  life  cycle  of  the  tick  consists  of  four  distinct  stages,  viz. :  egg 
(embryo),  larva,  nymph,  and  adult.  The  eggs  are  invariably  deposited 
on  the  ground  in  large  masses.  The  larvae  which  emerge  from  the 
eggs  are  minute  six-legged  creatures.  The  larvae  attach  themselves  to 
a  suitable  host,  upon  which  they  feed,  then  usually  drop  to  the  ground 
and  molt,  becoming  nymphs.  The  nymphs  have  eight  legs.  The  nymph 
waits  until  it  can  attach  itself  to  a  host,  engorges  blood,  usually  drops, 
molts  its  skin,  and  becomes  adult.  The  life  history  of  the  tick  differs 
from  the  mosquito  in  that  the  larval  and  pupal  stages  are  not  aquatic. 

It  was  first  shown  by  Smith  and  Kilborne  that  in  the  case  of  Texas 
fever  the  microorganism  within  the  adult  tick  passes  into  the  egg  and 
is,  therefore,  transmitted  "hereditarily"  to  the  next  generation.  The 
infection  of  Eocky  Mountain  spotted  fever,  of  canine  piroplasmosis,  and 
probably  also  that  of  African  tick  fever,  is  also  transmitted  by  the  female 


288  INSECT-BORNE    DISEASES 

to  the  next  generation.  Tick-borne  diseases  are  not  always  transmitted 
in  nature  in  this  way.  The  virus  may  Ije  transferred  directly  by  the 
larva,  the  nymph,  or  the  adult.  Thus,  some  ticks  leave  their  host  re- 
peatedly, and  the  parasites  they  draw  from  one  animal  may  be  injected 
into  another  animal  either  during  the  same  or  at  a  subsequent  stage  in 
the  development  of  the  tick. 

Ticks  upon  domestic  stock  may  be  controlled  by  dipping,  spraying, 
or  by  hand  methods.  The  arsenical  dip  has  practically  displaced  all 
others  for  the  destruction  of  ticks  in  the  various  parts  of  the  world. 
A  solution  of  0.2  per  cent,  arsenious  oxid  (AsgO.)  gives  the  best  results 
in  killing  ticks,  without  serious  injury  to  the  stock.  This  strength  of 
arsenic,  however,  will  not  kill  or  prevent  egg-laying  by  all  the  engorged 
females.  Crude  oils  have  been  used  to  a  considerable  extent  in  some  cases. 
They  are  more  expensive  than  the  arsenical  dip,  and  dangerous  to  cattle 
under  some  conditions.  Serious  losses  have  followed  the  use  of  heavy 
oils  in  dry  regions,  or  where  it  has  been  necessary  to  drive  the  cattle  any 
considerable  distance  after  dipping. 

The  formula  for  the  arsenical  dip  is  as  follows : 

Sodium  carbonate  (sal  soda) 24  lbs. 

Arsenic  trioxid  (white  arsenic) 8  lbs. 

Pine  tar 2  gals. 

Water  sufficient  to  make  500  gals. 

Sometimes  dipping  is  not  practical.  Instead  of  driving  cattle  con- 
siderable distances  to  dipping  vats  it  will  be  found  sufficient  to  treat 
them  thoroughly  by  hand  methods.  The  procedure  consists  simply  in 
applying  the  arsenical  mixture  liberally  by  means  of  rags,  mops,  or. 
brushes,  or  by  means  of  spray  pumps.  Crude  oil  may  be  used  by  hand 
instead  of  the  arsenical  solution.  For  most  tick-borne  diseases  cattle 
must  be  dipped  or  treated  weekly. 

The  following  diseases  transmitted  by  ticks  will  be  given  brief  con- 
sideration: Texas  fever  (Margaropus  annulatus),  South  African  tick 
fever  (Ornithodoros  savignyi),  Eocky  Mountain  spotted  fever  (Derma- 
centor  venustus),  and  relapsing  fever  (Ornithodoros  moubata).  Al- 
though it  is  probable  that  the  latter  disease  is  also  transmitted  by  the 
Argas  persicus  and  perhaps  other  biting  insects. 

TEXAS  FEVER 

Texas  fever  or  splenetic  fever  is  also  known  as  bovine  malaria,  tick 
fever,  and  hemoglobinuria.  The  disease  does  not  affect  man.  It  is 
confined  to  cattle,  and  is  of  very  great  economic  importance.  Texas 
fever  is  an  infection  which  should  be  understood  by  all  sanitarians,  on 


TICKS  289 

account  of  its  scientific  and  historic  importance.  The  cause  of  this  in- 
fection and  its  mode  of  transmission  were  ascertained  in  1893  by  Smith 
and  Kilborne.  The  discovery  that  the  tick  is  the  intermediate  host  of 
Texas  fever  opened  an  entirely  new  principle  in  the  sanitary  sciences. 

Texas  fever  is  caused  by  a  protozoon  parasite.  This  parasite  was 
first  named  Pyrosoma  bigeminum  on  account  of  the  twin-like,  pear- 
shaped  forms  commonly  seen  in  the  red  corpuscles.  This  genus  was 
changed  by  Patton  in  1895  to  Piroplasma.  These  terms  having  been 
preoccupied,  the  present  name  of  the  parasite  is  Babesia  bigemina.'^ 

The  contagium  is  carried  by  the  cattle  tick,  Boophilus  hovis,  now 
Margaropus  annulatus.  The  tick  lives  upon  the  skin  and  feeds  upon  the 
infected  blood,  becomes  sexually  mature  at  the  last  molt;  the  female 


Fig.  46. — The  Texas  Fever  Tick  (^Margaropus  annulatus). 

drops  to  the  ground  and  lays  about  2,000  eggs;  the  newly  hatched  larvae 
attach  themselves  to  the  skin  of  a  fresh  host,  which  they  infect.  This 
explains  the  long  extrinsic  period  of  incubation  in  this  disease,  40-60 
days;  30  days  of  which  are  required  for  the  development  of  the  larvae  and 
the  remainder  for  the  development  of  the  parasite  within  the  host. 

ROCKY  MOUNTAIN  SPOTTED  FEVER 

This  disease,  also  called  tick  fever  and  spotted  fever,  is  an  interest- 
ing infection  which  occurs  chiefly  in  the  Bitter  Eoot  Valley  of  Montana, 
centering  around  Missoula.  Cases  also  occur  in  the  neighboring  states 
of  Idaho  and  Wyoming,  also  Washington  and  California.  The  symptoms 
closely  resemble  those  of  typhus  fever,  including  a  petechial  eruption. 
Anderson  and  Goldberger  have  shown  that  typhus  fever  of  Mexico,  called 
tabardillo,  is  not  transmissible  to  guinea-pigs,  while  Eicketts  and  also 
King  independently  demonstrated  that  some  of  the  infected  blood  of  a 
case  of  Eocky  Mountain  fever  injected  into  a  guinea-pig  will  reproduce 

^  These  various  names  are  given  for  the  reason  that  they  are  all  found  in  the: 
literature. 

11 


290 


INSECT-BOENE    DISEASES 


the   chief  features   of  this   disease.      The   two    diseases   are,   therefore, 
distinct. 

Wilson  and  Chowning  first  suggested  that  the  tick  acts  as  the  car- 


FiG.  47. — Rocky  Mottntain  Spotted  Fevek  Tick.     (Dermacentor  venustus). 

1,  Adult  female,  unengorged,  dorsal  view;  2,  Adult  male,  dorsal  view;  3,  Adult  female, 
unengorged,  ventral  view;  4,  Adult  male,  ventral  view;  5,  Adult  female  in  act  of  de- 
positing eggs. 


rier  of  Eocky  Mountain  spotted  fever.  This  was  proven  hy  Eicketts  in 
1906,  who  showed  that  the  particular  tick  is  Dermacentor  occiden- 
talis  (now  venustus).     The  infection  may  be  transmitted  by  the  larva, 


TICKS  391 

the  nymph,  and  both  the  adult  male  and  female  ticks.  The  infection 
is  also  transmitted  hereditarily  through  the  ticks  to  their  larvae.  The 
disease  has  been  transmitted  by  the  tick  from  man  to  monkey  and  the 
guinea-pig,  and  also  from  monkey  to  monkey  and  from  guinea-pig  to 
guinea-pig.  A  few  infected  ticks  have  actually  been  found  by  Eicketts 
in  nature. 

Maver  ^  has  proved  by  experiment  that  different  species  of  ticks  col- 
lected from  various  regions  [Dermacentor  marginatus  (Utah),  Amhly- 
omma  americanus  linnaeus  (Missouri),  and  Bermacentor  variabilis 
(Mass.)]  are  able  to  transmit  the  virus  of  Rocky  Mountain  spotted 
fever.  The  inference  is  that  the  disease  may  find  favorable  conditions 
for  its  existence  in  localities  other  than  those  to  which  it  is  now  limited. 

One  attack  of  the  disease  establishes  a  rather  high  degree  of  immu- 
nity to  subsequent  attacks.  The  blood  serum  of  recovered  cases  con- 
tains protective  properties  of  a  rather  high  degree  for  guinea-pigs. 
The  virus  is  not  filtrable  through  a  Berkefeld  filter. 

Eicketts  found  "bodies"  in  the  blood  of  human  and  experimental  cases 
and  also  in  the  tissues  and  eggs  of  infected  ticks.  These  observations 
have  been  confirmed  by  Wolbach,^  who  finds  a  bacterium  in  the  lesions 
of  experimental  Eocky  Mountain  spotted  fever.  The  characteristic  form 
is  a  short  rod  growing  in  great  numbers  in  the  lesions  of  the  blood 
vessels,  testicle,  skin,  and  subcutaneous  tissues. 

The  prevention  of  Eocky  Mountain  spotted  fever  is  directed  en- 
tirely against  the  tick.  Ticks  are  to  be  avoided  in  the  infected  region. 
If  it  is  necessary  to  work  in  the  fields  and  woods  and  about  animals 
where  these  ticks  abound,  the  bites  should  at  once  be  cauterized  with 
strong  carbolic  acid.  A  vigorous  campaign  should  be  carried  on  by  the 
health  authorities  to  destroy  all  the  ticks  in  and  about  each  case  of  the 
disease. 

The  ultimate  control  of  Eocky  Mountain  spotted  fever  depends  upon 
the  suppression  of  the  Dermacentor  venustus.  This,  perhaps,  is  not  so 
hopeless  a  task  as  may  at  first  seem  likely.^  Henshaw  and  Birdseye  * 
found  ticks  either  in  the  immature  or  adult  stage  upon  twenty  species 
of  five  hundred  mammals  examined  in  and  around  Bitter  Eoot  Valley. 
The  mammalian  hosts  of  fever  ticks  fall  naturally  into  two  groups : 
those  that  harbor  chiefly  adult  ticks  and  those  that  harbor  the  younger 
stages.  In  the  former  class  belong  mountain  goats,  bears,  coyotes,  badg- 
ers, woodchucks,  and  possibly  elk,  deer,  mountain  sheep,  rabbits,  and 
domestic  stock,  such  as  horses,  cattle,  and  sheep.  Those  of  the  second 
class  harboring  the  nymphs  and  larvae  are  mainly  rodents  and  comprise 

^Jour.  Infect.  Dis.,  April  12,  1911. 

^Journal  of  Medical  Research,  March,  1916,  Vol.  XXXIV,  1,  pp.   121-126. 

*  Fortunately  the  Dermacentor  venustus  is  the  only  tick  in  the  endemic  region 
which  attacks  man. 

*  U.  S.  Dept.  of  Agr.,  Bureau  of  BIqL  Survey,  Cir..  S3. 


292  INSECT-BOENE    DISEASES 

ground  squirrels,  woodchucks,  chipmunks,  piue  squirrels,  mice,  and 
wood  rats.  These  smaller  animals  are  too  agile  to  permit  the  adult 
ticks  to  remain  upon  them. 

Unquestionably  the  great  bulk  of  fever  ticks  (Dermacentor  venus- 
tus)  which  become  engorged  in  the  Bitter  Root  Valley  do  so  on  do- 
mestic stock — horses,  cattle,  sheep,  and  sometimes  dogs.  They  ob- 
tain the  ticks  from  the  pastures  and  other  uncultivated  land  infested 
by  wild  animals.  It  is  obvious,  therefore,  that,  if  the  domestic  ani- 
mals in  the  valley  are  rendered  tick-free  by  dipping,  spraying,  or  by 
some  other  equally  effective  method,  the  chances  of  the  infection  of 
human  beings  will  be  vastly  lessened. 

The  measures  proposed  for  the  eradication  of  the  tick  are  as  follows : 
Clearing  and  cultivation  of  tillable  land;  burning  over  of  foothills  and 
"slashings";  killing  of  small  wild  mammals;  dipping  of  domestic  animals 
in  arsenical  dip;  spraying  and  removing  ticks  by  hand  from  domestic 
animals.  Each  one  of  these  measures  has  a  rational  basis  in  the  bi- 
onomics of  the  tick  Dermacentor,  but  although  all  of  these  methods  have 
been  attempted  on  the  west  side  of  the  Bitter  Root  Valley  for  three 
years  or  more  they  have  not  greatly  diminished  the  number  of  ticks 
to  be  found  or  the  number  of  deaths  from  spotted  fever.  The  extent 
and  inaccessibility  of  the  infested  territory,  and  the  consequent  expense 
have  rendered  the  problem  difficult.  Fricks  ^  recommends  sheep  grazing 
to  diminish  the  number  of  ticks,  for  the  reason  that  ticks  die  upon  sheep, 
and  many  of  the  engorged  females  are  not  fertilized  on  account  of  the 
difficulty  experienced  by  the  males  in  propelling  themselves  through  the 
thick  wool  in  search  of  the  females.  This  method  has  been  successful 
in  controlling  the  ticks  and  the  disease  in  the  Bitter  Root  Valley  in  1914. 

McClintic  infected  Rhesus  monkeys  and  guinea-pigs  with  spotted 
fever  and  treated  them  with  the  following  drugs :  salvarsan,  sodium 
cacodylate,  and  urotropin.  The  results  obtained,  however,  do  not  in- 
dicate that  any  of  these  drugs  possess  any  value  whatever  either  as  a 
prophylactic  or  in  the  treatment  of  spotted  fever,  but,  on  the  contrary, 
their  administration  seems  on  the  whole  rather  to  intensify  the  severity 
of  the  disease  in  the  animals  compared  with  the  course  of  the  disease 
in  the  controls.^ 

RELAPSING    FEVERS 

Relapsing  fever,  also  called  famine  fever,  tick  fever,  and  seven-day 
fever,  is  found  upon  all  the  five  continents  of  the  globe.  Epidemics  of 
this  disease  have  been  reported,  especially  from  Ireland  and  Russia.  The 
infection  prevails  in  India,  where  Vandyke  Carter  of  Bombay  made  his 

*  Hunter,  W.  D.,  and  Bishopp,  F.  C:  "The  Rocky  Mountain  Spotted  Fever 
Tick,"  Bureau  of  Entomology  Bull.  JVo.  105,  U.  S.  Dept.  of  Agr. 

=>  V.  8.  Puh.  Health  Reports,  Vol.  XXVII,  No.  20,  May  17,  1912,  and  XXVII, 
32,  Aug.  8,  1913,  p.   1647. 


TICKS  293 

classic  investigations.  Eelapsing  fever  was  epidemic  in  New  York  and 
Philadelphia  in  1869.  It  has  not  reappeared  in  epidemic  form,  but 
cases  occasionally  occur  in  various  parts  of  the  United  States.  The 
disease  has  receded  from  civilization  where  cleanliness  is  observed. 

The  term  "relapsing  fever"  includes  a  group  of  tropical,  febrile  in- 
fections caused  by  different,  but  very  closely  allied,  spirochetes — spiro- 
schaudinniae..  The  European  relapsing  fever  is  caused  by  S.  recurrentis 
and  transmitted  by  bedbugs  and  lice.  The  relapsing  fevers  of  East  and 
West  Africa  are  caused  by  S.  duttoni  and  transmitted  by  the  tick  {Or- 
nithodorus  moubata) .  The  North  African,  or  Algerian  Eelapsing  Fever 
is  caused  by  S.  berbera  and  is  transmitted  by  lice  (Pediculus  vestiment 
and  Pediculibs  capitis).  The  relapsing  fever  of  Asia  and  India  is  caused 
by  S.  Carteri  and  is  transmitted  by  lice.  These  various  spirochetes  re- 
semble each  other  morphologically,  but  show  a  difference  in  pathogenic- 
ity to  laboratory  animals  and  are  further  distinguished  from  each  other 
by  specific  agglutinins. 

Eelapsing  fever  is  characterized  by  sudden  onset,  intense  frontal 
headache  and  pains  of  back  and  limbs.  The  fever  continues  from  three 
to  five  days  and  falls  by  crisis.  The  temperature  remains  normal  for 
about  a  week,  when  the  fever  repeats  itself.  There  may  be  four  or  five 
such  relapses,  sometimes  ten.  The  spirochetes  are  found  in  the  pe- 
ripheral blood  only  during  the  febrile  period. 

Obermeier  in  1868  discovered  the  "spirillum"  in  the  blood — Spiril- 
lum ^  obermeieri.  Carter  and  Koch  in  1878  showed  that  the  infection  may 
be  transferred  to  apes  by  the  inoculation  of  the  blood  of  a  patient. 
Miinch  and  Moczutkowski  transferred  the  disease  by  the  inoculation  of 
relapsing  fever  blood  to  healthy  individuals.  Koch  and  also  Dutton  and 
Todd  succeeded  in  demonstrating  that  the  spirochetes  of  African  relaps- 
ing fever  multiplied  in  the  tick  {Ornitliodoros  moubata),  and  that  the 
bite  of  this  tick  may  convey  the  disease  to  healthy  men.  Other  insects, 
as  bedbugs,  fleas,  biting  flies,  and  lice,  may  convey  the  infection. 

Leishman  ^  has  demonstrated  that  the  Spirochaeta  duttoni  may  be 
transmitted  hereditarily  in  the  tick.  He  has  obtained  positive  results 
in  the  second  generation,  the  bites  of  which  were  infective  for  mice 
and  monkeys.  Attempts  to  carry  the  infection  to  the  third  generation 
in  the  tick  have  so  far  failed.  Leishman  considers  the  hereditary  trans- 
mission of  the  infection  as  biological  evidence  that  the  spirochetes  be- 
long to  the  protozoa  rather  than  the  bacteria. 

Schuberg  and  Manteufe  ^  found  that  a  temperature  of  22°  C.  is 
not  favorable  for  the  spirochete  in  the  Ornitliodoros  moubata.  This 
was  shown  by  experiments  upon  rats  in  which  the  infection  through 

^Spirillum  was   chang-ed   to   spirochaeta   and  then   to   microsohandiveraia. 

"Lancet,  Jan.  1,  1910,  Vol.  T,  p.  11. 

^  Zeitschr.  f.  Immunitcitsforschung,  Orig.  Bd.  4,  1910,  p.  512. 


294  INSECT-BORNE    DISEASES 

the  bite  of  the  tick  disappeared  more  quickly  at  22°  C.  than  at  higher 
temperatures. 

One  attack  protects  against  subsequent  attacks.  Second  attacks 
among  negroes  in  Africa  after  years  are  very  light.  The  only  sus- 
ceptible animals  are  man,  the  apes,  mice,  and  rats. 

The  prevention  of  relapsing  fever  is  based  upon  personal  and  domes- 
tic cleanliness  and  the  avoidance  of  tick  and  other  bug  bites.  Personal 
prophylaxis  depends  upon  keeping  aloof  from  vermin-infested  places, 
especially  where  the  disease  prevails.  Manson  suggests  that  a  mosquito 
net,  a  vermin  free  bed  well  off  the  ground,  and  a  night  light  are  indis- 
pensable in  Africa,  where  the  nocturnal  habits  of  the  Ornithodoros  mou- 
hata  render  the  hours  of  sleep  especially  dangerous.  Salvarsan  is  a  spe- 
cific remedy,  but  has  no  prophylactic  virtues. 


LICE 

The  insects  known  as  pediculi  or  lice  are  parasitic  during  their 
entire  life  on  warm-blooded  animals,  including  man.  They  are  de- 
graded, flat,  rather  elongate,  wingless  insects  with  a  small  head  and 
stout  legs  which  end  in  a  strong  claw,  opposable  to  a  projection  at 
the  tip  of  the  penultimate  joint.  The  mouth  parts  are  of  a  very  pe- 
culiar nature.  There  is  a  short  beak  or  proboscis  in  front.  Through 
this  beak  extends  a  slender  stylet  which  has  three  parts.  The  stylet 
is  used  to  pierce  the  skin  of  the  host  and  the  blood  is  thus  sucked  up 
through  the  proboscis.  Lice  usually  walk  sideways,  but  do  not  travel 
much  and  keep  fairly  close  to  one  host.  The  eggs  are  slightly  elongated 
and  fastened  to  the  hair  of  the  host  or  clothing.  They  hatch  in  about 
ten  to  fifteen  days,  the  young  coming  out  of  the  top  of  the  egg.  These 
young  do  not  differ  much  in  structure  from  the  adults,  but  are  paler 
in  color.  They  molt  their  skin  a  few  times,  probably  four,  before  they 
reach  the  matured  condition.  The  body  louse  has  about  5,000  offspring 
in  the  course  of  two  months.  The  nits  hatch  out  in  3  or  4  days  and  are 
sexually  mature  in  about  18  days.  The  males  are  less  numerous  than  the 
females,  and  ordinarily  smaller.  There  are  several  generations  each 
year,  dependent,  doubtless,  on  the  temperature,  but  the  life  history  is 
not  thoroughly  known  for  any  species. 

It  is  the  blood-sucking  habits  of  lice  which  render  them  dangerous 
parasites  and  capable  of  transmitting  disease  from  one  host  to  another. 
Fortunately,  they  do  not  readily  change  hosts,  so  that  they  cannot  be 
considered  quite  as  dangerous  as  some,  more  active  parasites.  There 
are  about  50  or  60  known  species  which  are  arranged  in  15  genera 
and  4  families.  It  is  Pediculus  vestimenti  the  clothes  or  body  louse, 
which  is  mainly  responsible  for  the  transmission  of  typhus  fever. 


LICE  295 

Three  species  of  lice  are  found  upon  man:  (1)  Pediculus  capitis 
(now  humanus),  the  ova  of  which  are  attached  to  the  hairs  and  can 
readily  be  seen  as  white  specks,  known  as  nits.  (2)  Pediculus  vesti- 
menti  (or  corporis),  the  clothes  or  body  louse,  lives  on  the  clothing, 
and  in  sucking  the  blood  causes  minute  hemorrhagic  specks,  commonly 
about  the  neck,  back^  and  abdomen.  (3)  Pediculus  (or  Phthiriu^)  pubis 
or  crab  louse  is  found  in  the  parts  of  the  body  covered  with  short  hairs, 
as  the  pubes;  more  rarely  the  axilla  and  eyebrows. 

The  prevention  of  lousiness 'is  almost  entirely  a  matter  of  personal 
cleanliness.  However,  the  most  scrupulous  individuals  may  become 
infested.  Lice  may  be  passed  directly  from  one  person  to  another,  or 
occasionally  may  be  carried  by  flies,  or  other  means,  Beds  in  hotels 
and  sleeping  cars  are  sources  of  infection.     (See  also  page  1095.) 

Human  lice  can  be  destroyed  with  kerosene,  turpentine,  tincture  of 
Cocculus  indicus,  dichloromethane,  and  other  insecticides.  The  ordinary 
germicides  are  for  the  most  part  not  effective.  Baking,  boiling,  or  steam- 
ing are  efficient.  It  is  comparatively  easy  to  destroy  the  adult  insect,  but 
the  eggs  are  resistant.     For  further  details  see  pages  297  and  1095. 

For  public  lice  white  precipitate  or  mercurial  ointment  should  be 
used  and  the  parts  thoroughly  washed  two  or  three  times  a  day  with 
soft  soap  and  water. 

The  principal  disease  known  to  be  transmitted  by  lice  is  typhus 
fever,  but  they  are  suspected  in  relapsing  fever  and  other  infections. 

TYPHUS  FEVER 

Typhus  fever  was  formerly  confused  with  typhoid  fever;  Louis  in 
1829  named  typhoid  fever  but  it  remained  for  one  of  his  pupils,  Gerhard, 
clearly  to  lay  down  the  differences  between  the  two  diseases.  Previous  to 
that  time  typhus  fever  was  prominent  and  prevailing,  while  typhoid 
fever  was  unknown  as  such  and  probably  did  not  occur  in  great  epidemics. 
Now  the  situation  is  reversed ;  typhoid  fever  has  become  pandemic,  while 
typhus  fever  has  receded  with  civilization  and  improvements  in  sani- 
tation. Epidemics  of  typhus  fever  are  now  rare,  except  in  a  few 
places,  notably  the  Grand  Plateau  of  Mexico,  where  the  disease  prevails 
extensively  and  with  a  high  mortality.  It  prevails  also  in  certain  por- 
tions of  Ireland,  in  ^  some  provinces  of  France,  portions  of  Eussia, 
particularly  Poland  and  the  east  sea  provinces,  and  at  times  in  Tunis, 
Algiers,  and  Egypt  in  Northern  Africa;  in  Spain,  Hungary,  and  cer-, 
tain  provinces  of  the  Baltic  States;  also  in  China.  In  the  ten  years  1871- 
80  in  Ireland  7,495  deaths  were  reported  from  typhus  fever;  in  the  3 
years  1909-11  the  number  had  fallen  to  143.  The  outbreak  in  Serbia 
(1915)  and  other  parts  of  the  war  zone  is  fresh  in  mind. 

Typhus  fever  last  prevailed  in  epidemic  form  in  the  United  States 


296  INSECT-BOIINE    DISEASES 

in  New  York  in  1881-82  and  again  in  1892-93,  and  in  Philadelphia  in 
1883.  Since  then,  except  for  a  few  sporadic  cases  at  our  seaports,  the 
disease  has  been  thought  to  be  non-existent  in  the  United  States.  How- 
ever, Anderson  and  Goldberger  ^  have  recently  shown  that  the  symp- 
tom-complex known  as  "Brill's  disease"  is  in  reality  typhus  fever,  and 
that  the  typhus  fever  of  Europe  and  the  typhus  fever  or  "tabardillo" 
of  Mexico  are  the  same  disease.  It  is  now  evident  that  typhus  fever  has 
been  smouldering  in  New  York  a  great  many  years,  certainly  since 
1896,  when  Brill  first  observed  cases  of  what  was  known,  previous  to 
the  work  of  Anderson  and  Goldberger,  as  "Brill's  disease."  The  disease 
in  New  York  is  generally  mild,  but  seems  to  be  on  the  increase;  there- 
fore, we  face  a  new  sanitary  problem  in  this  country. 

Typhus  fever,  when  prevalent  in  epidemic  form,  has  been  said  by 
the  older  writers  to  be  one  of  the  most  highly  contagious  of  febrile 
diseases,  doctors  and  nurses  and  others  in  close  contact  with  the  disease 
being  almost  invariably  stricken.  Typhus  fever  claims  more  victims  in 
the  medical  profession  than  any  other  epidemic  disease.  The  sad  case  of 
Ricketts,  who  lost  his  life  in  endeavoring  to  unravel  this  pathological 
puzzle  in  Mexico,  is  still  fresh  in  mind. 

The  period  of  incubation  of  typhus  fever  is  from  five  to  twenty 
days,  with  an  average  of  twelve.  One  attack  apparently  confers  a  very 
definite  immunity,  second  attacks  being  very  nniisual.  The  cause  of 
the  infection  is  described  by  Plotz  as  a  small,  Gram-nositive,  anaerobic 
bacillus.^ 

Methods  of  prevention  have  been  given  a  sound  foundation  through 
the  recent  work  of  Nicolle  of  France,  Ricketts  and  Wilder  of  the  Uni- 
versity of  Chicago,  and  of  Anderson  and  Goldberger  of  the  U.  S.  Pub- 
lic Health  Service.  It  is  now  clear  that  the  virus  exists  in  the  circulating 
blood  during  at  least  all  of  the  febrile  stage  and  possibly  in  some  in- 
stances for  thirty-six  hours  after  the  crisis. 

The  disease  may  be  transmitted  by  blood  inoculations  to  chimpan- 
zees and  probably  to  all  the  lower  monkeys.  The  virus  as  it  exists  in 
the  circulating  blood  is  held  back  by  the  Berkefeld  filter.  It  is  not  killed 
by  freezing  for  eight  days,  but  is  deprived  of  virulence  by  heating  at  55° 
C.  for  15  minutes. 

Monkeys  that  recover  from  the  experimental  disease  show  a  definite 
immunity  to  subsequent  infection. 

Nicolle  in  1909  was  the  first  to  rej^ort  the  transmission  of  typhus 
fever  by  the  bite  of  the  body  louse  {Pediculus  vestimenti) .  Since  then 
his  work  has  been  confirmed  by  Ricketts  and  Wilder  and  by  Ander- 

^  Anderson,  John  F.,  and  Goldberger,  Joseph :  "The  relation  of  so-called 
Brill's  disease  to  typhus  fever ;  an  experimental  demonstration  of  their  identity." 
Public  Health  Reports,  XXVII,  February  2,  1912. 

^Jour.  A.  M.  A.,  May  IG,  1914,  p.  1556.  Jour,  of  Infectious  Diseases,  17,  I, 
July,  1915,  pp.  1-68. 


LICE  297 

son  and  Goldberger.  These  latter  authors  have  recently  shown  that 
the  head  louse  (Pediculus  capitis)  may  also  transmit  the  infection. 
The  role  of  the  body  louse  in  the  transmission  of  typhus  fever  will 
receive  ready  support  from  students  of  the  epidemiology  of  typhus 
fever,  for  this  disease  presents  all  the  characteristics  of  an  insect-borne 
disease.  Since  the  transmission  of  the  disease  by  the  body  louse  has 
been  shown,  we  can  understand  why  typhus  fever  prevails  in  epidemic 
form  only  in  overcrowded,  filthy,  unhygienic  surroundings,  and  the 
truth  is  readily  understood  of  the  oft-quoted  sentence  of  Hirsch,  that 
"the  history  of  typhus  is  the  history  of  human  wretchedness." 

The  disease  has  greatly  decreased  from  civilized  centers  with  dim- 
inution in  lousiness.  The  prevention  of  typhus  now  focuses  itself  upon 
the  eradication  of  the  body  louse.  Fortunately,  this  insect  does  not 
of  itself  travel  far,  but  it  may  be  carried  many  miles  upon  the 
body  or  in  the  clothing.  The  eradication  of  the  body  louse  is 
largely  a  question  of  personal  cleanliness,  and,  so  far  as  typhus 
fever  is  concerned,  is  closely  interwoven  with  squalor,  ignorance,  and 
poverty. 

Lice  and  nits  can  be  destroyed  with  kerosene  (coal  oil)  and  its  various 
products  such  as  gasoline  and  benzine;  turpentine;  dichlorethylene  or 
tetrachlorethane.  The  latter  two  substances  are  not  inflammable  and 
hence  are  most  practicable.  For  public  health  purposes  best  results  are 
obtained  by  immersion  of  verminous  garments  and  bed  clothes  in  gasoline 
or  tetrachlorethane.  Danger  from  fire  when  gasoline  or  benzine  are 
employed  may  be  avoided  by  using  such  a  bath  and  extractor  as  are 
employed  in  a  dry-cleaning  apparatus.  Where  the  clothing  is  not  injured 
by  immersion  in  water,  the  garments  may  be  steeped  for  one-half  an 
hour  at  12°  C.  (54°  F.)  in  a  soap  solution  containing  2  per  cent,  of 
trichlorethylene  or  10  per  cent,  of  tetrachlorethane.  Better  still,  fabrics 
such  as  bed  and  body  linen,  as  well  as  outer  garments,  may  be  baked, 
boiled  or  steamed.  Both  lice  and  nits  are  killed  by  heating  to  70°  C. 
(158°  F.)  in  ten  minutes.  Dry  heat  is  more  efl'ective  than  moist  heat  in 
destroying  lice  and  their  eggs.  The  louse  can  be  revivified  after  immer- 
sion for  one  minute  in  water  at  100°  C.  Exposure  to  dry  heat  at  the 
same  temperature  and  for  the  same  length  of  time  kills  both  insects  and 
nits. 

The  common  phenol  disinfectants  u.sed  in  public  health  work  fail  to 
kill  lice  and  nits,  even  after  steeping  one-half  hour  at  ordinary  tempera- 
tures; at  65°  these  substances  are  effective.  The  volatile  oils  have  no 
direct  insecticidal  effect.  Substances  such  as  oil  of  wintergreen,  oil 
of  cloves,  eucalyptus,  oil  of  thyme,  fennel,  anise,  etc.,  do  not  destroy  lice, 
but  when  the  body  is  anointed  with  such  substances  may  act  as  a  deter- 
rent. Perhaps  the  best  substance  to  anoint  the  skin  with  is  an  oint- 
ment made  of  5  per  cent,  naphthalene  in  petroleum.    Turpentine  destroys 


298  INSECT-BORNE    DISEASES 

both  lice  and  their  eggs,  but  must  be  used  with  care.  For  the  manage- 
ment of  head  lice  see  page  1095. 

Now  that  we  know  how  the  disease  is  spread,  measures  may  be  in- 
telligently applied  for  its  prevention,  these  measures  being  primarily 
directed  to  the  destruction  of  Pediculi  and  their  eggs.  When  a  case  of 
typhus  fever  is  discovered  the  patient  should  be  removed  to  a  vermin- 
free  room  or  hospital.  The  patient's  clothes  should  be  removed  and 
baked,  steamed  or  placed  in  boiling  water  or  dipped  in  gasoline,  tri- 
chlorethylene  or  tetrachlorethane,  for  the  destruction  of  lice  and  their 
eggs.  The  patient's  hair  should  be  clipped  and  he  should  then  be  given 
a  thorough  sponging  or  bathing  with  a  soap  solution  containing  2  per 
cent,  trichlorethylene  or  10  per  cent,  tetrachlorethane.  The  room  or 
apartment  from  which  the  patient  was  removed  should  be  thoroughly 
fumigated  by  the  burning  of  sulphur  for  the  destruction  of  lice,  and  the 
room  kept  sealed  for  at  least  12  hours.  Sulphur  dioxid  does  not  kill  lice 
eggs.  The  room  may  also  be  sprayed  or  mopped  with  kerosene  or  tetra- 
chlorethane. 

The  fact  should  be  kept  constantly  in  mind  that  the  louse  is  neces- 
sary for  the  spread  of  typhus  fever,  just  as  the  mosquito  is  for  the 
spread  of  malaria,  and  our  efforts  toward  prophylaxis  should  be  con- 
ducted with  this  point  continuously  in  mind.  Even  with  the  knowledge 
of  the  mode  of  transmission  of  typhus  fever  individual  prophylaxis  is 
still  somewhat  difficult,  especially  where  infected  insects  abound  in  thickly 
populated  centers. 

Those  whose  duties — isuch  as  doctors  and  nurses — take  them  into 
an  infected  area  should  avoid  outer  clothing  which  is  liable  to  brush 
against  the  furniture,  bedding,  etc.  The  skirts  of  nurses  should  be 
sufficiently  short  to  avoid  touching  the  floor.  Personal  prophylaxis  may 
also  be  assisted  through  the  use  of  gloves,  veils,  netting,  leggins,  and 
similar  mechanical  devices.  Eubber  gloves  should  be  worn  and  a  one- 
piece  suit  with  adhesive  plaster  to  cover  openings  at  the  neck  and  wrist, 
or  the  edges  may  be  smeared  thick  with  a  sticky  substance  used  on  fly- 
paper (castor  oil  and  colophony,  see  page  214).  In  the  Serbian  cam- 
paign a  union  suit  extending  from  the  toes  to  the  neck  with  attached 
gloves  was  worn  next  to  the  skin.  This  was  covered  with  the  customary 
hospital  gown  and  shoes.  The  hair  was  clipped  short.  A  surgeon's  cap 
and  mask  completed  the  outfit. 

The  outer  garments  should  be  removed  while  standing  on  a  sheet — 
the  whole  then  wrapped  up  and  sent  to  be  steamed,  boiled,  baked  or 
dipped  in  gasolene.  The  clothing  worn  by  those  attending  cases  of  the 
disease  or  where  lice  are  present  should  be  frequently  changed  and  close 
attention  given  to  personal  cleanliness. 

Persons  who  have  typhus  fever  should  be  selected  for  the  care  of 
typhus  patients  and  for  work  in  infected  places  whenever  possible. 


BEDBUGS 


299 


BEDBUGS 

Cimex  lectularius  has  been  carried  by  man  to  all  parts  of  the  in- 
habited world.  It  has  become  a  true  domesticated  animal  and  has 
accommodated  itself  well  to  the  environment  of  human  habitations. 
The  bedbug  has  no  wings  and  a  very  flat  body,  which  enables  it  to  hide 
in  the  narrowest  chinks  and  cracks  of  beds  and  walls.  It  may  subsist 
for  incredibly  long  periods  of  time  without  food.  It  is  nocturnal  in  its 
habits. 

The  pronounced  odor  of  this  insect  is  produced  by  certain  glands 
opening  on  the  back  of  the  abdomen  in  young  bugs  and  on  the  under 
side  of  the  metasternum  in  the  adults.     The  odor  is  common  to  most 


Fig.  48. — The  Bedbug. 
a,  Adult  female,  gorged  with  blood;  b.  Same  from  below;  c,  Rudimentary  wing  pad; 
d,  Mouth  parts.     (Marlatt.) 


members  of  the  group  to  which  this  insect  belongs.     It  is  useful  in 
plant  bugs,  protecting  them  from  their  enemies. 

The  bedbug  undergoes  an  incomplete  metamorphosis,  the  young  be- 
ing very  similar  to  their  parents  in  appearance,  structure,  and  habits. 
The  eggs  are  white,  oval  objects  having  a  little  projecting  rim  around 
one  edge,  and  are  laid  in  batches  of  from  six  to  fifty,  in  cracks  and 
crevices  where  the  bugs  go  for  concealment.  The  eggs  hatch  in  a  week 
or  ten  days  and  the  young  escape  by  pushing  the  lid  within  the  pro- 
jecting rim  from  the  shell.  At  first  the  larvae  are  yellowish-white,  nearly 
transparent,  the  brown  color  of  the  more  mature  insect  increasing  with 
the  later  molts.  During  the  course  of  development  the  skin  is  shed  five 
times,  and  with  the  last  molt  the  minute  wing  pads,  characteristic  of  the 
adult  insect,  make  their  appearance.  Marlatt  found  that  under  favor- 
able conditions  about  seven  weeks  elapse  from  the  egg  to  the  adult  insect, 


300  INSECT-BOKNE    DISEASES 

and  that  the  time  hetween  eacli  luolt  averages  ahout  eight  days.  Without 
food  they  may  remain  unchanged  for  an  indefinite  time.  Ordinarily 
but  one  meal  is  taken  between  molts,  so  that  each  bedbug  must  puncture 
its  host  five  times  before  becoming  mature,  and  at  least  once  afterward 
before  it  can  develop  eggs. 

The  presence  of  bedbugs  in  a  house  is  not  necessarily  an  indication 
of  neglect  or  carelessness.  They  are  very  apt  to  get  into  trunks  and 
satchels  of  travelers  or  may  be  introduced  in  the  homes  upon  the  cloth- 
ing of  servants,  workmen,  or  visitors.  The  bedbug  is  quite  capable  of 
migrating  from  one  house  to  another.  Ships  are  almost  sure  to  be 
infested  with  them.  They  are  not  specially  limited  by  cold,  and  are 
known  to  occur  well  north.  They  thrive  particularly  in  old  houses 
which  are  full  of  cracks  and  crevices,  in  which  they  can  conceal  them- 
selves beyond  easy  reach.  The  biting  organ  of  the  bedbug  is  similar 
to  that  of  other  Hemipterous  insects.  The  skin  of  the  host  or  victim 
is  pierced  with  four  thread-like  hard  filaments  or  setae,  which  glide 
over  each  other  with  an  alternating  motion  and  thus  pierce  the  skin. 
The  blood  is  drawn  up  through  the  beak,  which  is  closely  applied  to 
the  point  of  puncture.  The  bite  of  the  bedbug  is  decidedly  irritating  to 
some  indivi(^uals,  resulting  in  a  swelling  and  disagreeable  inflamma- 
tion. 

The  Suppression  of  Bedbugs,. — On  account  of  its  habits  of  conceal- 
ment the  bedbug  is  usually  beyond  the  reach  of  the  ordinary  insect 
powders,  which  are  practically  of  no  avail  against  it.  If  iron  or  brass 
bedsteads  are  used,  the  eradication  of  the  insect  is  made  easier.  Large 
wooden  bedsteads  furnish  many  cracks  and  crevices  into  which  the  bugs 
can  force  their  flat  thin  bodies,  and  extermination  becomes  a  matter 
of  considerable  difficulty.  The  most  practical  way  of  eradicating  bed- 
bugs is  by  a  very  liberal  application  of  gasolene,  benzine,  kerosene,  or 
any  other  of  the  petroleum  oils.  These  must  be  introduced  into  all  crev- 
ices with  small  brushes  or  feathers,  or  by  injecting  with  small  syringes; 
a  saturated  solution  of  corrosive  sublimate  in  water  is  also  of  value,  and 
oil  of  turpentine  may  be  used  in  the  same  way.  The  liberal  use  of  scald- 
ing hot  water  or  soap  suds  wherever  it  may  be  employed  without  damage 
to  furniture  is  also  an  effectual  method  of  destroying  both  eggs  and  active 
bugs.  Fumigation  with  hydrocyanic  acid  gas,  sulphur  dioxid,  or  carbon 
bisulphid  are  alike  effective.  Several  fumigations  may  be  necessary. 
Crevices  in  warm  parts  of  the  room  are  favorite  nesting  places,  as  under 
picture  mouldings,  or  over  door  frames.  Finally  the  room  should  be 
renovated,  all  imperfections  and  cracks  closed  and  sealed  with  paint. 

In  sleeping  cars  and  other  places  where  hydrocyanic  gas  may  be 
used  without  fear  of  accidents,  this  is  the  most  efficacious  and  least 
destructive  method. 

The  bedbug  has  long  been  under  suspicion  as  an  intermediate  host 


BEDBUGS  301 

in  the  transference  of  many  communicable  infections.  There  is  more 
than  a  suspicion  that  it  is  concerned  in  relapsing  fever,  in  kala-azar, 
and  it  has  been  accused  of  carrying  the  bacteria  of  tuberculosis,  leprosy, 
and  many  other  diseases. 

KALA-AZAB 

Kala-azar  is  a  tropical  infection  characterized  by  anemia  and  enlarge- 
ment of  the  spleen.  It  is  caused  by  a  parasite  which  occurs  in  great 
numbers  in  the  spleen  and  which,  upon  culture  media,  develops  into  a 
flagellated  organism  resembling  the  trypanosomes.  The  parasites  were 
discovered  by  Leishman  and  Donovan  in  the  spleen  and  liver  and  the 
epithelium  of  the  blood  vessels.  Manson  and  Low  found  similar  bodies 
in  the  ulcerous  mucous  membranes  of  the  intestines,  and  Marchand  and 
Ledingham  found  the  same  peculiar  bodies  in  the  cells  of  the  bone 
marrow  and  lymphatic  glands.  Eogers  cultivated  the  parasites  from  the 
spleen  of  patients  suffering  with  kala-azar  upon  agar  streaked  with  fresh 
human  blood.  Flagellate  forms  developed.  This  was  confirmed  by  Chris- 
tophers, who  used  Novy's  method  of  growing  trypanosomes  upon  the 
water  of  condensation  of  blood  agar  tubes.  The  kala-azar  parasites 
grown  in  artificial  culture  media  have  a  cilium  but  no  membrane. 

ROACHES 

Eoaches  are  among  the  commonest  and  most  offensive  of  the  insects 
which  frequent  human  habitations.  They  are  under  suspicion  of  convey- 
ing several  infections.  There  are  no  less  than  a  thousand  species  of  the 
family  Blattidae.  Four  of  these  have  become  domesticated  and  cosmopoli- 
tan. They  are  Periplaneta  americana,  Periplaneta  australasiae,  Blatta 
orientalis  and  Blatta  germanica. 

The  main  difference  between  Periplaneta  americana  and  Periplaneta 
australasiae  is  that  the  Australian  roach  differs  strikingly  in  the  brighter 
and  more  definitely  limited  yellow  band  on  the  prothorax,  and  in  the 
yellow  dash  on  the  side  of  the  wings. 

Blatta  orientalis  or  black  beetle,  is  the  common  European  and  Eng- 
lish species.  The  female  is  nearly  wingless  in  the  adult  state.  Blatta 
germanica,  the  German  roach,  has  become  worldwide  in  distribution :  in 
this  country  it  is  styled  the  Croton  bug.  It  is  now  the  commonest 
and  best  known  of  the  domestic  roaches.  It  is  light  brown  in  color,  and 
characteristically  marked  on  the  thorax  with  two  dark  brown  stripes. 
It  is  the  smallest  of  the  domestic  roaches,  but  multiplies  more  rapidly 
than  any  of  them.  It  is  also  more  active  and  wary  than  the  larger 
species,  and  more  difficult  to  eradicate. 

Structure  and  Habits. — Eoaches  are  smooth,  slippery  insects,  in 
shape  broad  and  flattened.    The  head  is  bent  downward  so  that  the  mouth 


302  INSECT-BORNE    DISEASES 

parts  are  directed  backward,  and  the  eyes  directly  downward,  conforming 
to  their  grovelling  habits.  The  antennae  are  very  long  and  slender,  often 
having  upward  of  100  joints.  The  males  usually  have  two  pair  of  wings. 
In  some  species,  as  the  Croton  bug,  the  females  are  nearly  wingless. 
The  legs  are  long  and  powerful,  and  armed  with  numerous  strong  bristles 
or  spines.  The  mouth  parts  are  well  developed  and  have  strong  biting 
jaws  like  those  -of  a  grasshopper,  enabling  these  insects  to  eat  all  sorts 
of  substances. 

House  roaches  are  particularly  abundant  in  pantries,  kitchens, 
bakeries,  and  other  warm  places.  They  are  nocturnal  in  habits.  Their 
numbers  are  often  not  realized  unless  they  are  surprised  in  their  mid- 
night feasts.  Domestic  roaches  are  practically  omnivorous,  feeding  on 
almost  any  dead  animal  matter,  cereal  products  and  food  materials  of 
all  sorts.  They  are  believed  to  be  cannibalistic.  They  eat  or  gnaw 
woolens,  leather,  and  frequently  damage  the  cloth  and  leather  bindings 
of  books.  They  soil  everything  with  which  they  come  in  contact,  leaving 
a  nauseous,  roachy  odor.  Eood  so  tainted  is  beyond  redemption.  This 
odor  comes  partly  from  the  excrement,  but  chiefly  from  a  dark-colored 
fluid  exuded  from  the  mouth  of  the  insect,  and  also  in  part  from  the 
scent  glands.  Occasionally  they  migrate,  which  accounts  for  the  way  in 
which  new  houses  frequently  become  suddenly  overrun  with  these  vermin. 

The  eggs  are  brought  together  within  the  abdomen  of  the  mother 
into  an  egg  capsule,  which  is  a  hard,  horny  pod.  It  is  retained  in  this 
position  sometimes  for  weeks,  or  until  the  young  larvae  are  ready  to 
emerge.  The  young  are  very  much  like  the  adults,  except  in  point  of 
size,  and  in  lacking  wings.  They  pass  through  a  number  of  molts,  some- 
times as  many  as  seven.  The  development  of  the  roach  is  slow,  and 
probably  under  the  most  favorable  conditions  rarely  more  than  one 
generation  per  year  is  produced.  The  abundance  of  roaches  is  therefore 
apparently  not  accounted  for  so  much  by  their  rapidity  of  multiplication 
as  by  their  unusual  ability  to  preserve  themselves  from  ordinary  means 
of  destruction,  and  by  the  scarcity  of  natural  enemies. 

Natural  enemies  of  the  roach  are  mice,  rats,  guinea-fowl,  ttee-frog, 
ichneumon  fly,  and  other  insectivorous  animals. 

The  warfare  against  roaches  consists  of :  (1)  cleanliness;  (2)  elimina- 
tion of  breeding  and  hiding  places;  (3)  fumigation;  (4)  poisons;  (5) 
traps ;  ( 6 )  natural  enemies.  Scrupulous  cleanliness  and  the  keeping  of 
food  in  jars  or  places  inaccessible  to  the  roach  is  of  prime  importance. 
All  unnecessary  corners,  cracks  and  imperfections  in  the  structure  of  the 
building  that  favor  breeding  and  hiding  places  must  be  eliminated. 
Roaches  may  be  killed  with  hydrocyanic  acid  gas,  and  also  with  sulphur 
dioxid — several  fumigations  are  sometimes  necessary.  The  best  poison 
for  roaches  is  sodium  fluorid.  This  substance  very  finely  ground  and 
mixed  with  meal  of  some  sort  forms  the  basis  of  most  roach  powders 


BEDBUGS  303 

found  upon  the  market.  The  powder  should  be  liberally  dusted  in  all 
corners,  drawers,  closets,  and  runways.  Other  poisons  sometimes  used 
are:  pyrethrum  powder,  flowers  of  sulphur,  phosphorous  paste,  contain- 
ing 1  or  2  per  cent,  of  phosphorous  in  sweetened  flour.  Plaster-of-Paris, 
1  part,  flour  3  or  4  parts,  may  be  set  near  a  convenient  flat  plate  contain- 
ing pure  water.  The  insects  eat  the  mixture,  become  thirsty  and  drink, 
when  the  plaster-of-Paris  sets  and  clogs  the  intestines.  Many  roaches 
may  be  trapped  in  a  deep,  smooth  basin  or  jar.  Sticks  leading  up  to  the 
rim  of  the  trap  make  runways  for  the  insects,  which  slip  into  the  trap 
but  cannot  get  out.  The  best  bait  for  these  traps  is  stale  beer.  The 
Croton  bug  is  too  wise  to  be  thus  trapped. 

The  roach  has  been  shown  by  Fibiger  ^  to  become  infested  with  a 
round  worm.  When  these  infested  roaches  are  eaten  by  rats,  a  cancerous- 
like  groAvth  develops  in  the  stomachs  of  the  rats,  apparently  due  to  the 
irritating  presence  of  these  worms.  Herms  and  Nelson  ^  and  also  Long- 
fellow ^  have  shown  the  possibility  of  the  conveyance  of  typhoid  and 
other  infections  by  means  of  the  roach.  When  we  consider  that  house 
roaches  feed  upon  all  kinds  of  breadstuffs,  milk  and  its  products,  meat, 
clothing,  cooked  and  raw  food ;  that  they  migrate  from  one  apartment  to 
another,  following  water  and  drain  pipes,  from  cellar  and  sick  room  to 
living  rooms  and  bedrooms;  that  they  infest  kitchens,  store  rooms  and 
toilets,  opportunity  is  evidently  offered  to  drag  infection  mechanically 
from  one  place  to  another.  Eoaches  must  therefore  be  regarded  as  a 
sanitary  menace. 

Eeferences. — The  literature  upon  insects  and  insect-borne  diseases 
is  very  widely  distributed.  Many  of  the  entomological  facts  contained 
in  this  chapter  have  been  taken  from  "The  Insect  Book"  by  L.  0.  Howard 
and  the  many  excellent  publications  of  Howard  and  his  colleagues  of 
the  Bureau  of  Entomology,  Department  of  Agriculture.  The  Govern- 
ment publications  may  be  had  upon  application  to  the  Superintendent  of 
Documents,  Washington,  D.  C.  Many  of  the  facts  concerning  the 
prevention  and  destruction  of  mosquitoes  have  been  taken  from  articles 
in  the  Public  Health  Reports  of  the  Public  Health  Service.  In  the  chap- 
ter upon  insecticides  free  reference  has  been  made  to  my  own  book  upon 
"Disinfection  and  Disinfectants,"  as  well  as  to  my  other  writings  and 
unpublished  work  in  different  phases  of  this  subject.  Other  references 
are  cited  in  the  text.' 

*  Fibiger,  J.:    Berliner  hlin.  Wochenschr.,  Feb.  17,  1913,  L,  No.  7,  pp.  289-332. 
="  Herms,  W.  B.,  and  Nelson,  Y.:     Am.  Jour.  Pub.  Health,  Sept.,  1913,  III, 
9,  p.  929. 

'Longfellow,  R.  C:     Am.  Jour.  Pui.  Health,  Jan.,  1913,  III,  1,  p.  58. 


CHAPTER  V 
MISCELLANEOUS  DISEASES 

INFANTILE   PARALYSIS 

(Acute  Anterior  Poliomyelitis) 

An  entirely  new  literature  upon  the  subject  of  infantile  paralysis 
is  now  being  constructed.  Wickman  of  Sweden,  in  1905-06,  gave  us  a 
new  symptomatology,  and  defined  clinical  types  not  before  recognized. 
Wickman  made  the  first  systematic  study  of  the  disease  from  an  epi- 
demiological point  of  view,  and  found  evidence  that  it  was  contagious, 
though  usually  slightly  so.  He  directed  especial  attention  to  several 
factors  in  its  spread,  viz. :  routes  of  travel,  public  gatherings  of  children, 
abortive  or  ambulant  cases,  and  healthy  intermediate  carriers.  In  the 
spring  of  1909  Landsteiner  and  Popper  succeeded  in  transmitting  the 
disease  to  two  monkeys  by  inoculating  them  with  the  spinal  cord  of  a 
child  who  had  died  of  infantile  paralysis.  Later  in  the  year  Flexner  and 
Lewis  obtained  the  same  results,  and  further  transmitted  the  infection 
from  monkey  to  monkey  through  an  indefinite  number  of  passages.  To 
Harbitz  and  Scheel  of  Norway  we  are  indebted  for  formulating  the 
pathologic  anatomy  of  the  affection. 

Infantile  paralysis  is  now  properly  regarded  as  a  communicable  dis- 
ease. The  virus  is  filtrable,  that  is,  "ultramicroscopic."  The  virus  has 
been  grown  by  Flexner  and  Noguchi  as  minute  globoid  bodies  arranged 
in  pairs,  chains  and  masses  in  artificial  cultures.  (/.  A.  M.  A.,  Peb.  1, 
1913,  LX,  5,  362.) 

It  appears  that  infantile  paralysis  is  becoming  more  and  more  com- 
mon and  more  widespread  of  late  years.  This  increase  cannot  be  ac- 
counted for  by  the  fact  that  the  disease  is  now  better  known  and  more 
readily  recognized.  Bergenholtz,  in  1881,  described  the  first  outbreak 
with  sufficient  accuracy  to  accept  infantile  paralysis  as  a  new  disease. 

Eecent  outbreaks  have  occurred  in  Norway  and  Sweden,  Austria, 
Germany,  Holland,  England,  Spain,  France,  the  United  States,  and 
Cuba.  Of  the  8,054  cases  reported  in  5  years  (1905-09),  the  United 
States  contributed  5,514  cases  or  about  five-sevenths  of  the  total  number. 
The  number  of  outbreaks  and  the  number  of  cases  have  progressively 
increased,  as  shown  in  the  following  table : 

304 


li^FANTILE    PAEALYSIS  305 

Av.  No.  of  Cases 
Cases       Outbreaks     per  Outbreak 

1880-1884  23  2  11.5 

1885-1889  93  7  13. 

1890-1894  151  4  38. 

1895-1899  ,  345  23  15. 

1900-1904  349  9  39. 

1905-1909  8,054  25  322. 

Epidemics  of  poliomyelitis  have  prevailed  in  all  quarters  of  the  world. 
The  disease  has  been  most  prevalent  in  the  northern  parts  of  Europe 
and  of  the  United  States.  Epidemics  have  been  more  severe,  and  the 
case  rates  have  been  higher,  in  small  towns  and  rural  districts  than  in 
the  more  densely  populated  cities.  Even  in  the  cities  the  disease  does 
not  especially  strike  the  crowded  districts.  Cold  countries  having  marked 
seasonal  variations  in  temperature  have  been  most  affected,  but  the 
disease  is  always  most  prevalent  in  the  warm,  dry  months,  from  May  to 
November  in  the  northern  hemisphere  and  November  to  May  in  the 
southern  hemisphere.  Sporadic  cases  may  occur  at  any  time  throughout 
the  year.  The  great  majority  of  cases  occur  in  children  under  five  years 
of  age.  From  the  standpoint  of  prevention  it  is  important  to  note  that 
social  and  hygienic  conditions  apparently  have  no  influence  whatever  in 
determining  the  infection.  All  classes  are  affected  in  about  equal  pro- 
portion. 

The  virus  of  the  disease  is  present  in  greatest  virulence  or  concen- 
tration in  the  spinal  cord  of  infected  persons  and  animals.  One  one- 
hundredth  of  a  cubic  centimeter  of  an  emulsion  of  cord,  or  less,  is  suf- 
ficient to  infect  a  monkey.  The  virus  is  also  quite  constantly  present 
in  the  brain  and  other  organs  and  tissues,  as,  for  instance,  the  mucous 
membrane  of  the  nose  and  pharynx,  the  mesenteric  glands,  the  axillary 
and  inguinal  lymph  nodes,  also  in  the  blood,  and  in  the  cerebrospinal 
fiuid.  The  virus  has  been  demonstrated  in  the  intestinal  secretions. 
The  suspicion  that  the  alvine  discharges  may,  therefore,  be  virulent  is 
sufficient  indication  that  they  should  be  disinfected  in  all  cases  until 
further  knowledge  of  the  subject  is  at  hand. 

The  experimental  disease  in  monkeys  may  be  produced  by  injecting 
the  virus  directly  into  the  central  nervous  system,  preferably  the  brain. 
Young  rabbits  ^  and  guinea-pigs  may  likewise  be  infected.  Monkeys  may 
also  be  infected  by  introducing  the  virus  subcutaneously  or  into  the 
peritoneal  cavity,  and  even  by  intravenous  inoculation.  They  have  been 
infected  by  placing  virulent  material  upon  the  healthy  mucous  membrane 
of  the  nose  and  also  by  inhalation  of  the  infectious  material  forced  into 
the  trachea,  and  finally  by  introducing  the  virus  into  the  stomach,  along 
^  Rosenau  and  Havens:     Journal  of  Experimental  Medicine,  April,  1916. 


306  MISCELLANEOUS    D1SP:ASES 

with  an  opiate,  to  restrain  peristalsis.  Leiner  and  Weisner  have  infected 
monkeys  through  the  uninjured  nasal  mucous  membrane.  I  have  ob- 
tained similar  results.  Monkeys  have  so  far  never  been  known  to  contract 
the  disease  spontaneously,  even  though  they  are  kept  in  intimate  associa- 
tion with  infected  monkeys.  There  are  many  paralytic  diseases  of  the 
lower  animals,  but,  so  far  as  known,  infantile  paralysis  as  a  natural 
infection  is  peculiar  to  man.  Eosenau  and  Brues,  and  also  Anderson 
and  Frost,  have  transmitted  the  disease  from  monkey  to  monkey  through 
the  bite  of  the  stable  fly. 

Resistance  of  the  Virus. — The  virus  of  anterior  poliomyelitis  is  killed 
by  a  temperature  of  45°  to  50°  C.  in  half  an  hour;  also  by  comparatively 
weak  disinfectants,  such  as  a  1-500  solution  of  permanganate  of  potash, 
1  per  cent,  menthol  in  oil,  a  powder  containing  menthol,  0.5  per  cent., 
salol,  5  per  cent.,  boric  acid,  20  per  cent.  (Landsteiner  and  Levaditi), 
and  a  dilution  of  perhydrol  (Merck)  equivalent  to  1  per  cent,  of  peroxid 
of  hydrogen.  The  virus  is  not  destroyed  by  very  low  temperatures  nor 
by  drying  over  caustic  potash,  or  in  vacuo  for  a  considerable  period. 
A  virulent  cord  has  been  kept  for  almost  5  months  in  pure  glycerin 
without  losing  its  virulence,  resembling  in  this  respect  rabies,  vaccinia, 
and  other  filterable  viruses,  and  differing  for  the  most  part  from  non- 
spore-bearing  pathogenic  bacteria  which  are  usually  killed  by  pure  gly- 
cerin in  a  short  while.  The  virus  remains  virulent  in  ordinary  water 
for  31  days,^  and  the  same  length  of  time  in  milk  first  sterilized  by  heat. 

Immunity. — One  attack  of  infantile  paralysis  apparently  confers  a 
high  degree  of  immunity.  Recurrent  cases  and  second  attacks  have 
been  reported.  Monkeys  which  have  recovered  from  the  infection  show 
a  high  degree  of  resistance,  in  that  they  are  not  susceptible  to  infec- 
tion by  again  inoculating  them,  and  their  blood  serum  contains  anti- 
bodies capable  of  rendering  the  virus  harmless.  That  is,  if  the  blood 
serum  of  an  immune  monkey  is  mixed  with  an  emulsion  of  virulent 
spinal  cord  and  the  mixture  allowed  to  stand  for  several  hours,  the  virus 
is  no  longer  capable  of  producing  the  infection  in  susceptible  animals. 
This  property  has  been  used  by  Anderson  and  Frost  to  corroborate  the 
clinical  diagnosis  in  abortive  cases.  The  blood  of  a  person  who  has  not 
had  the  disease  does  not  neutralize  the  virus;  therefore,  if  the  injection 
of  the  virus  previously  treated  with  human  serum  fails  to  produce  the 
infection  in  susceptible  monkeys,  it  may  be  taken  as  evidence  that  the 
serum  contained  specific  antibodies  and  came  from  an  individual  who  has 
had  the  disease. 

Modes  of  Transmission. — Contact  theory  (based  upon  the  as- 
sumption TPIAT  the  virus  IS  DISCHARGED  FROM  THE  MOUTH  AND  NOSE 
AND  ENTERS  THROUGH  THE  SAME  cpiannel). — There  is  evidence  to  sup- 
port the  theory  that  the  disease  is  directly  transmissible  from  person  to 

*  Levaditi  and  Pasti,  Annal.  de  I'lnst.  Pasteur,  XXV,  11,  805. 


INFANTILE    PARALYSIS  307 

person  and  there  is  a  suspicion  that  healthy  carriers  play  an  important 
rule  in  spreading  the  infection.  This  view  was  enunciated  by  Wickman 
and  received  support  through  the  experiments  of  Kling,  Pettersson  and 
Wernstedt,  and  also  Flexner.  It  is  known  that  the  mucous  membrane 
of  the  nose  and  throat  contains  the  virus,  and  in  one  case  the  salivary 
glands  were  shown  to  be  infective.  Osgood  and  Lucas  demonstrated 
that  the  nasal  mucous  membrane  of  two  monkeys  experimentally  inocu- 
lated with  poliomyelitis  remained  infective  for  6  weeks  in  one  case  and 
5%  months  in  another.  This  very  important  observation  strengthens 
the  suspicion  of  the  existence  of  chronic  human  carriers.  If  healthy 
carriers  continue  to  spread  the  infection  months  after  the  attack,  it  in- 
creases the  difficulty  of  suppressing  the  disease,  and  further  renders 
doubtful  the  efficiency  of  strict  isolation  and  prophylactic  measures  di- 
rected only  to  persons  in  the  acute  stage  of  the  disease.  The  fact  that 
the  mucous  membrane  contains  the  virus  is  not,  however,  sufficient  proof 
that  the  virus  is  liberated  and  discharged  in  sufficient  amount  in  the 
secretions  from  the  mouth  and  nose  to  be  a  menace.  In  a  series  of  18 
cases  Eosenau,  Sheppard  and  Amoss  ^  were  unable  to  demonstrate  the 
virus  in  the  nasal  and  buccal  secretions  obtained  from  persons  in  various 
stages  of  convalescence.  Strauss  ^  had  similar  negative  results  in  a  series 
of  10  cases.  On  the  other  hand,  Kling,  Pettersson  and  Wernstedt  ^  re- 
port successful  results ;  by  experiments  upon  monkeys  they  demonstrated 
the  infectiousness  of  buccal  and  intestinal  secretions  of  living  subjects. 
Flexner  has  recently  also  reported  one  successful  attempt  in  demonstrat- 
ing the  virus  in  the  buccal  secretions. 

The  Insect-borne  Theory. — Infantile  paralysis  shows  no  tendency 
to  prevail  in  congested  centers  or  to  spread  in  hospitals,  schools,  institu- 
tions, and  other  crowded  places;  its  seasonal  prevalence  corresponds  to 
the  seasonal  prevalence  of  most  insects,  and  does  not  correspond  to  the 
seasonal  prevalence  of  diseases  spread  through  secretions  of  the  mouth 
and  nose,  such  as  diphtheria,  scarlet  fever,  smallpox,  etc.  Many  other 
factors,  brought  to  light  by  the  studies  of  the  State  Board  of  Health  of 
Massachusetts  upon  the  epidemiology  of  the  disease,  under  the  able 
direction  of  Dr.  Mark  Richardson,  indicate  that  the  disease  is  not  a  con- 
tagious one.  These  studies  *  gradually  focused  attention  upon  some 
insect,  the  stable  fly  (Stomoxys  calcitrant)  in  particular.     Rosenau  and 

^Rosenau,  M.  J.,  Sheppard,  P.  A.  E.,  Amoss,  H.  L.,  Boston  Med.  and  Surg. 
Jour.,  May  25,  1911,  CLXIV,  21,  pp.  743-748. 

'Strauss,  I.,  J.  A.  M.  A.,  April  22,  1911,  LVI,  16,  1192. 

^  Kling,  C.,  Pettersson,  A.,  and  Wernstedt,  W.,  Report  from  the  State  Medical 
Institute  of  Sweden  to  the  XV  International  Congress  on  Hygiene  and  Demog- 
raphy, Washington,  D.  C,  1912.  Also,  Zeitschr.  f.  Immunitdtsforch.  u.  exper. 
Therapie,  Bd.  XII,  Jena,  1912. 

"Richardson,  M.  W.,  Monthly  Bull.,  State  Board  of  Health  of  Mass.,  Sept., 
1912,  7,  9,  pp.  308-315. 

Lovett,  R.  W.,  Report  to  the  Mass.  State  Board  of  Health,  1907. 

Report  to  the  Mass.  State  Board  of  Health,  1908,  1909,  1910,  1911. 


308  MISCELLANEOUS    DISEASES 

Brues  ^  demonstrated  the  virus  may  sometimes  be  transmitted  from 
monkey  to  monkey  through  the  bite  of  the  stable  fly.  These  results  were 
soon  confirmed  by  Anderson  and  Frost.^  The  insect-borne  theory  seems 
to  fit  the  case  as  the  disease  is  known  in  Massachusetts.  Subsequent  work 
by  Eosenau,  Anderson  and  others  has  given  negative  results;  it  will, 
therefore,  require  much  additional  study  to  determine  what  role  Stomoxys 
calcitrans  plays  in  spreading  the  infection  in  nature. 

Other  Theories. — It  has  been  suggested  that  the  virus  may  be 
air-borne  in  the  sense  that  it  is  carried  in  the  dust.  Neustaedter  and 
Thro  ^  claim  to  have  infected  monkeys  from  dust  collected  from  sick 
rooms.  Infected  food,  or  transmission  through  wounds  and  other  means, 
have  not  been  ruled  out  of  consideration. 

Prevention. — No  definite  or  efl:ective  system  of  prevention  can  be 
formulated  until  we  are  sure  of  the  mode  of  transmission.  Meanwhile 
health  authorities  are  entirely  justified  in  requiring  cases  to  be  reported, 
isolated,  and  all  known  lines  of  preventive  measures  applied,  such  as 
disinfection,  screening,  and  guarding  against  insects,  allaying  unneces- 
sary dust,  etc.  A  fly  campaign  directed  with  especial  reference  to  the 
stable  fly  is  plainly  indicated,  and  the  infection  must  also  be  fought  as 
one  conveyed  from  man  to  man  directly.  Until  the  modes  of  transmis- 
sion of  the  disease  are  established,  however,  we  can  have  no  confidence 
in  our  prophylactic  measures,  which  most  resemble  the  old  "shotgun" 
prescription. 

The  following  measures  are  recommended :  The  patient  should  be 
isolated  as  completely  as  possible  in  a  clean,  bare  room,  well  screened 
to  keep  out  insects.  This  is  a  good  practice  despite  the  fact  that  the 
disease  shows  no  tendency  to  spread  in  children's  asylums,  hospitals, 
and  other  institutions,  or  even  in  the  home.  The  same  statement,  how- 
ever, was  made  of  typhoid  fever  not  many  years  ago.  Visiting  should 
be  interdicted  and  only  the  necessary  attendant  should  be  allowed  to 
come  in  contact  with  the  patient.  All  discharges,  including  sputum, 
nasal  secretions,  urine,  and  feces,  should  be  thoroughly  disinfected,  and 
special  care  should  be  taken  that  cups,  spoons,  remnants  of  food,  etc., 
which  may  have  become  contaminated  by  the  patient  are  burned,  scalded, 
or  otherwise  purified. 

Towels,  bed  linen,  and  other  fabrics  should  be  boiled  or  dipped  into 
a  germicidal  solution  strong  enough  to  destroy  the  typhoid  bacillus.  The 
nurse  and   physician    should   observe   the   same   precautions    regarding 

^Eosenau,  M.  J.,  and  Brues,  C.  T.,  Monthly  Bull.,  State  Board  of  Health  of 
Mass.,  Sept.,  1912,  7,  9,  pp.  314-318.  Also  Brues  and  Sheppard,  Jour,  of  Econom. 
Entomology,  Aug.,  1912,  V,  4,  305. 

''Anderson,  J.  F.,  and  Frost,  W.  H.,  Pub.  Health  Reports,  Oct.  25,  1912, 
XXVII,  43,  pp.  1733-1736. 

^  Neustaedter,  M.,  and  Thro.,  W.  C,  tf.  Y.  Med.  Jour.,  Sept.  23,  1911, 
XCIV,  13. 


CHICKENPOX  309 

their  hands  and  clothing  as  are  recommended  in  attending  a  case  of 
scarlet  fever. 

The  period  during  which  the  isolation  should  be  maintained  cannot 
even  be  guessed  at.  Children  are  usually  not  permitted  to  return  to 
school  for  at  least  three  weeks,  but,  if  chronic  carriers  play  the  important 
role  now  suspected,  this  time  would  be  far  too  short  in  many  instances. 

Since  the  virus  can  be  killed  experimentally  by  a  1  per  cent,  solu- 
tion of  peroxid  of  hydrogen,  antiseptic  gargles,  sprays,  and  nose  washes 
of  this  solution  are  recommended  to  be  used  by  the  patient,  the  nurse, 
and  physician,  and  other  members  of  the  family.  In  the  presence  of 
an  epidemic,  street  and  house  dust  should  be  kept  down  by  sprinkling, 
oiling,  and  the  other  means  employed  for  this  purpose.  Dust  should 
be  allayed  whether  there  is  an  epidemic  of  infantile  paralysis  or  not. 
During  epidemics  children  should  be  kept  away  from  public  gatherings, 
prohibited  from  using  public  drinking  cups,  and  special  attention  given 
to  the  diet  to  prevent  gastro-intestinal  disorders,  for  many  a  case  of 
infantile  paralysis  starts  with  a  digestive  upset. 


OHICKENPOX 

Chickenpox  (varicella)  is  usually  regarded  as  one  of  the  minor  com- 
municable diseases  in  that  the  mortality  is  low,  complications  and  sequelae 
not  frequent :  chickenpox  is  not  always  a  harmless  disease ;  when  it  runs 
through  an  institution  with  many  small  children  it  occasionally  develops 
malignancy.  It  may  leave  disfiguring  scars ;  sepsis  or  erysipelas  some- 
times originate  in  the  pustules ;  complications,  such  as  pneumonia,  neph- 
ritis, and  gangrene  of  the  skin  also  occur. 

Chickenpox  is  very  readily  communicable  and  spreads  through  fam- 
ilies or  institutions,  and  also  in  more  or  less  widespread  epidemics.  The 
cause  of  the  disease  and  its  modes  of  transmission  are  not  known.  The 
virus  is  contained  in  the  content  of  the  vesicle.  The  disease  is  peculiar 
to  man ;  animal  inoculations  have  so  far  proven  negative.  The  period  of 
incubation  is  probably  from  fourteen  to  sixteen  days ;  the  maximum  for 
public  health  purposes  is  21  days.  One  attack  produces  a  definite  im- 
munity.    No  age  is  exempt. 

Health  officers  should  require  cases  of  chickenpox  to  be  reported,  if 
for  no  other  reason  than  that  it  is  often  mistaken  for  smallpox.  The 
differential  diagnosis  between  chickenpox  and  smallpox  is  often  an  im- 
portant and  difficult  public  health  matter.  The  distinction  may  be  made 
by  introducing  some  of  the  contents  of  the  vesicle  into  the  skin  of  a 
well- vaccinated  person.  If  smallpox,  an  immediate  reaction  results;  if 
chickenpox,  no  reaction  results.  Monkeys  are  not  susceptible  to  chicken- 
pox  but  may  be  given  smallpox.    The  differential  diagnosis  may  also  be 


310  MISCELLANEOUS    DISEASES 

made  from  the  presence  of  vaccine  bodies  in  smallpox  and  their  absence 
in  chickenpox. 

The  differential  diagnosis  may  be  made  in  doubtful  cases  by  a  his- 
tological examination  of  the  pock,  or  by  inoculating  the  contents  of  the 
vesicle  upon  the  cornea  of  rabbits.  In  sections  of  the  skin  lesion  the 
vaccine  bodies  are  found  in  smallpox,  not  in  chickenpox;  the  vesicle  of 
the  former  is  multilocular,  the  latter  unilocular.  The  vesicle  upon  the 
cornea  of  rabbits  produced  by  smallpox  is  distinct  and  contains  the  vac- 
cine bodies;  the  lesion  resulting  from  chickenpox  is  trifling  and  does 
not  contain  the  vaccine  bodies. 

Eabbits  previously  vaccinated  with  vaccine  virus  will  give  a  marked 
intradermal  reaction  with  smallpox  vesicle  contents  in  from  twenty-four 
to  forty-eight  hours,  but  will  not  give  such  a  reaction  with  varicella 
vesicle  contents.^ 

The  prevention  of  chickenpox  depends  upon  isolation  and  disinfec- 
tion at  the  bedside.  Children  with  chickenpox  should  not  be  permitted 
to  go  to  school. 

Kling  ^  favors  vaccination  with  chickenpox  virus,  in  the  face  of  an 
epidemic  in  an  institution.  The  response  to  such  vaccination  is  slight 
and  local.  The  virus  is  taken  from  a  fresh,  clear  vesicle  and  introduced 
into  the  skin.  Eight  days  later  red  papules  appear  at  the  site  of  "vac- 
cination," which  next  day  develop  into  typical  vesicles  of  chickenpox, 
with  a  slight  reddened  areola.  There  are  no  general  symptoms.  Previous 
vaccination  with  smallpox  does  not  prevent  a  positive  reaction  to  vac- 
cination with  chickenpox,  thus  emphasizing  the  essential  difference  be- 
tween the  two  diseases.  An  epidemic  of  chickenpox  at  the  Stockholm 
Children's  Hospital  in  August,  1914,  was  cut  short  by  vaccinating  all 
the  well  children  with  the  virus  from  a  chicken  pock. 


GLANDERS 

Glanders  or  farcy  is  a  widespread  communicable  disease  of  horses, 
mules,  asses,  and  other  animals,  and  is  readily  communicated  to  man. 
Cats  may  become  infected  by  eating  the  flesh  of  glandered  horses.  Goats 
also  have  the  disease.  Cattle  are  immune.  Guinea-pigs  and  field  mice  are 
very  susceptible  by  experimental  methods ;  the  home  mouse  has  a  natural 
immunity.  In  both  man  and  horses  it  is  remarkable  for  its  fatality.  The 
disease  is  characterized  by  the  formation  of  inflammatory  nodules  either 
in  the  mucous  membrane  of  the  nose  (glanders)  or  in  the  skin  (farcy). 
The  nodules  break  down,  leaving  crater -like  ulcers.    On  the  skin  the  farcy 

^JouT.  A.  M.  A.,  Vol.  LXV,  No.  7,  August  14,  1915,  p.  588,  Force  and  Beck- 
with. 

"Berl.  klin.  Wochenschr.,  Nov.  10,  1913,  L,  45,  p.  2083, 


GLANDEES  311 

buttons  break  down  and  discharge  an  oily  material.  The  mortality  is 
about  50  per  cent.    Glanders  occurs  both  as  an  acute  and  chronic  disease. 

Glanders  is  caused  by  the  Bacillus  mallei,  which  corresponds  to 
the  spore-free  bacteria  so  far  as  its  resistance  is  concerned.  In  gen- 
eral the  bacillus  of  glanders  is  killed  by  the  same  agents  used  against 
the  tubercle  bacillus,  which  it  resembles  in  some  particulars. 

The  infection  may  be  introduced  into  the  system  either  through  the 
skin  or  mucous  membrane,  and  is  usually  communicated  directly  from 
the  horse  to  man  by  contact  with  the  infected  discharges.  The  disease 
is  sometimes  communicated  from  man  to  man.  Washerwomen  have  be- 
come infected  from  the  clothes  of  a  patient. 

The  bacillus  of  glanders  does  not  have  a  spore.  It  is  comparatively 
frail  and  readily  destroyed  by  the  usual  physical  and  chemical  germi- 
cidal agencies  used  against  spore-free  bacteria.  The  bacillus,  however, 
is  frequently  protected  by  albuminous  matter  or  buried  in  the  dirt  of 
stables,  water  troughs,  harnesses,  and  other  objects.  While  the  naked 
germs  of  glanders  are  readily  destroyed,  they  are  frequently  hard  to 
get  at;  cleanliness  is,  therefore,  imperative. 

The  prevention  of  glanders  in  man  depends  primarily  upon  the  sup- 
pression of  the  disease  in  horses.  The  only  difficulty  in  controlling 
the  disease  in  horses  lies  in  the  early  diagnosis  and  recognition  of  mild 
or  missed  cases,  which  are  very  common.  Horses  affected  with  occult 
or  latent  glanders  are  important  factors  in  the  propagation  of  the  in- 
fection, especially  in  the  crowded  parts  of  cities.  The  clinical  diagnosis 
in  the  frank  cases  is  made  without  difficulty  from  the  characteristic 
symptoms  and  the  lesions,  but  laboratory  aid  is  necessary  to  discover  the 
mild  cases. 

Diagnosis. — The  diagnosis  of  glanders  may  be  made  by:  (1)  the 
mallein  test;  (2)  the  agglutination  test;  (3)  the  Strauss  reaction; 
(4)  isolation  of  B.  mallei  in  pure  culture;  and  (5)  complement  fixa- 
tion. All  these  tests  serve  a  definite  purpose.  However,  the  mallein 
test,  the  agglutination  test,  and  the  Strauss  reaction  have  certain  limita- 
tions. The  isolation  of  the  glanders  bacillus  in  pure  culture  is  definite 
and  final,  but  time-consuming.  The  diagnosis  of  glanders  by  complement 
fixation  is  at  present  our  most  reliable,  most  satisfactory,  and  quickest 
method  of  recognizing  the  disease. 

The  Mallein  Test. — Mallein  is  a  product  of  the  glanders  bacillus 
corresponding  to  tuberculin.  The  injection  of  mallein  into  normal  ani- 
mals produces  no  reaction,  whereas  the  injection  into  glanderous  ani- 
mals causes  a  rise  in  temperature  and  a  local  reaction  about  the  lesions. 
With  the  mallein  test  a  large  proportion  of  latent  and  occult  cases  of 
glanders  can  be  diagnosed,  but  the  test  must  be  made  and  interpreted 
by  an  experienced  veterinarian,  else  the  results  may  be  unreliable.  The 
mallein  test  fails  to  give  a  typical  reaction  in  a  considerable  number  of 


313  MISCELLANEOUS    DISEASES 

glanderous  animals;  on  the  other  hand,  a  reaction  may  follow  the  injec- 
tion of  mallein  in  the  absence  of  glanders.  Thus  mallei n  is  not  an  en- 
tirely reliable  diagnostic  agent  and  has  never  been  considered  as  specific 
in  the  detection  of  this  disease  as  tuberculin  for  the  diagnosis  of  tuber- 
culosis. 

The  ophthalmic  test  for  glanders  is  reliable,  and  has  a  great  advan- 
tage over  other  tests  on  account  of  its  very  simple  application.  It  is  only 
necessary  to  drop  into  one  of  the  eyes  of  the  animal  three  drops  of  con- 
centrated mallein,  or  to  dip  a  camel's-hair  brush  into  mallein  and 
introduce  this  into  the  conjunctival  sac.  The  reaction  usually  com- 
mences in  five  or  six  hours  after  the  introduction  of  the  mallein  and 
lasts  from  twenty-four  to  thirty-six  hours.  A  positive  reaction  is 
manifested  by  swelling  of  the  eyelids  and  a  purulent  secretion  from  the 
tested  eye. 

The  Agglutination"  Test. — The  agglutination  test  is  of  value  in 
all  cases  of  recent  infection,  the  blood  serum  possessing  a  very  high 
agglutinating  power — 1-1,000  and  higher.  In  chronic  glanders  the  ag- 
glutinating power  of  the  blood  may  be  very  low — 1-400  or  less ;  in  some 
cases  even  lower  than  that  of  normal  blood  serum — which  may  be  1-800 
and  even  higher.  It  is,  therefore,  plain  that  agglutination  tests  alone  do 
not  constitute  an  entirely  satisfactory  diagnostic  method  for  glanders. 
It  may  be  used  as  an  adjunct  to  other  tests. 

The  Strauss  Eeaction. — The  Strauss  ^  reaction  for  the  diagnosis 
of  glanders  consists  in  inoculating  male  guinea-pigs  into  the  peritoneal 
cavity  with  material  containing  virulent  B.  mallei,  which  causes  an 
enlargement  of  the  testicles,  involving  the  scrotum;  the  testes  become 
glued  to  their  sheaths.  A  positive  reaction  associated  with  organisms 
resembling  those  of  glanders,  and  typical  cultures  obtained  from  the 
lesions,  are  unfailing  evidence  of  the  presence  of  the  specific  virus. 
Failure  to  obtain  the  reaction  is  not  proof  that  a  suspected  specimen 
may  not  have  come  from  a  horse  or  animal  with  glanders.  Arms  ^  recom- 
mends that  it  is  better  to  use  more  than  one  guinea-pig  in  testing 
suspected  material,  and  that,  before  inoculating,  it  is  well  to  make  a 
microscopic  examination  as  a  guide  to  the  dosage.  A  culture  made  from 
the  swab  often  aids  in  the  early  diagnosis.  Guinea-pigs  should  be  kept 
under  observation  for  a  month,  and  if  a  lesion  of  any  kind  is  present 
an  autopsy  should  be  made  and  cultures  taken. 

The  Isolation  of  B.  Mallei  in  Pure  Culture. — The  bacillus 
of  glanders  may  be  isolated  by  introducing  some  of  the  suspected  ma- 
terial subcutaneously  and  also  intraperitoneally  into  male  guinea-pigs. 
In  this  way  pure  cultures  may  be  obtained  from  the  pus  or  necrotic 
foci  in  the  spleen,  which  follow  subcutaneous  inoculation;  or  from  the 

^  Compt.  Rend.  Acad.  d.  Sc,  1889,  CVIIT,  p.  530. 
"J.  A.  M.  A.,  IN,  7,  Aug.  13,  1910,  p.  591. 


GLANDEES  313 

characteristic  enlargement  of  the  testicle  which  is  observed  in  animals 
inoculated  intraperitoneally.  The  organism  isolated  must  be  studied 
for  cultural,  morphological,  and  biological  characters.  The  isolation  of 
the  bacillus  in  pure  culture  gives  positive  information  of  unquestioned 
character  in  any  critical  case.  The  method  is  not  generally  applicable 
to  the  diagnosis  of  glanders  because  it  requires  too  much  time  and 
may  occasionally  fail  to  discover  the  bacillus. 

Complement  Fixation. — In  1909  Schiitz  and  Schubert  ^  published 
the  results  of  their  important  work  on  the  application  of  the  method 
of  complement  fixation  for  the  diagnosis  of  glanders.  The  splendid 
results  obtained  constitute,  without  doubt,  the  most  reliable  method 
for  the  diagnosis  of  glanders  which  we  have  at  our  command  at  the 
present  time.  The  complement  fixation  test  is,  in  fact,  one  of  the  most 
specific  of  the  biological  tests  in  immunity.  It  is  readily  applicable  to 
the  case  of  glanders.  The  essential  elements  used  in  the  test  are  as 
follow : 

The  hemolytic  system  consists  of  the  washed  red  blood  corpuscles 
of  a  sheep  and  the  blood  serum  of  a  rabbit  which  has  been  injected 
with  the  washed  red  blood  corpuscles  of  a  sheep.  Strong,  vigorous 
rabbits  are  selected  and  three  injections  of  the  sheep's  corpuscles  are 
made  at  intervals  of  7  days,  using  7  c.  c,  10  c.  c,  and  12  c.  c.  of  the 
red  corpuscles  of  the  sheep  suspended  in  like  amounts  of  isotonic  salt 
solution.  The  blood  serum  of  a  rabbit  so  treated  contains  the  hemolytic 
amboceptors.  The  rabbit's  blood  serum  is  heated  to  50°  C.  for  half 
an  hour  in  order  to  destroy  the  complement.  The  titer,  or  amount  of 
amboceptor  contained  in  the  rabbit  serum,  must  be  determined.  The 
hemolytic  system,  then,  consists  of  rabbit  serum  containing  ambocep- 
tor, plus  washed  red  blood  corpuscles  of  the  sheep. 

Complement. — The  complement  is  contained  in  the  fresh  blood  serum 
of  a  healthy  guinea-pig.  The  blood  serum  of  the  guinea-pig  should  be 
titrated  in  order  to  determine  the  amount  of  complement  present.  It  is 
always  necessary  to  determine  the  smallest  quantity  of  complement  to 
be  used  for  the  final  test. 

Antigen. — The  antigen  consists  in  an  extract  obtained  by  shaking 
glanders  bacilli  in  salt  solution.  The  bacillus  is  grown  in  pure  cul- 
ture on  2  per  cent,  acid  glycerin  agar.  A  luxuriant  growth  upon  the 
surface  of  the  medium  is  usually  obtained  in  48  hours.  This  is  sus- 
pended in  salt  solution,  heated  to  60°  C.  for  four  hours  in  order  to 
kill  the  bacilli.  After  heating  the  dead  bacilli  are  shaken  in  the  salt 
solution  in  a  special  apparatus  for  four  days.  The  bacilli  are  separated 
in  the  centrifuge  and  the  clear  supernatant  liquid  is  drawn  off  and  pre- 

^  Schiitz  and  Schubert :  "Die  Ermittelung  der  Eotzkrankheit  mit  Hilfe  der 
Komplementablenkungsmethode."  Archiv  fur  ivissenschaftliche  und  praktische 
Tierheilkunde.     Bd.  35,  Heft  1  and  2,  pp.  44-83,  1909. 


314 


MISCELLANEOUS    DISEASES 


served  with  carbolic  acid.     The  strength  of  this  extract  must  be  deter- 
mined by  suitable  methods  of  titration. 

Technic. — The  test  is  carried  out  by  adding  together,  in  proper 
proportions,  the  following:  (1)  The  blood  serum  of  the  horse  to  be 
tested;  (2)  the  antigen  (extract  of  glanders  bacilli);  (3)  complement 
(fresh  guinea-pig  serum)  ;  and  (4)  the  hemolytic  system.  If  the  blood 
serum  of  the  horse  to  be  tested  contains  the  specific  amboceptors  these 
will  unite  with  the  bacteria,  fix  the  complement,  and  thus  prevent  hemol- 


+   2=3    = 


fiemofiytic  o/nAa 
ffe</6/ooi/ce//.      ceptor(/fo6i,/^ 


cept, 


^nicn  c/reJi/cot/ceff 
and  omAocaaAr 
(rto  nefTio/usts). 


fjo^y)      ^€/no'ustsju>///rQiiJh 


B. 


+ 


.JjocMrro/uT/c     union  of\ 


^tn^ter 


omQOcepfor'. 


i/MWfn9«i/^ 


Comp/e" 


D. 


+ 


^% 


Mocfen'a. 
CG/o/rf/sKs 
/OnT/'gen). 


/u>,-ff,ff/one/ers     (■'"'/''^'"ent 


Sacter/o/u 


/Va/ieme/ysia  M>'//res  u/tr 

Fig.  49. — Diagrammatic  Rephesentation   of   Complement  Fixation.     Mohler  and 
Eichorn,  Bull.  136.  B.A.I.,  U.  S.  Dept.  of  Agriculture. 

A,  Hemolytic  system. 

B,  Bacteriolytic  system. 

C,  Negative  reaction  with  normal  horse  serum. 

D,  Positive  reaction  with  glandered  horse  serum. 


ysis.  If  the  blood  serum  of  the  horse  to  be  tested  does  not  contain 
these  specific  amboceptors,  this  fixation  of  the  complement  cannot 
take  place  and  hemolysis  results.  Therefore,  the  absence  of  hemolysis 
means  the  presence  of  glanders,  and  vice  versa.  The  tests  must  always 
be  carried  out  with  controls  and  carefully  conducted  as  to  the  amount 
of  each  substance  used,  the  temperature  and  time.^  (See  also  page  445.) 
PreventioiL. — When  glanders  is  discovered  or  suspected  among  horses 
in  a  stable,  the  horses  in  the  infected  stable  should  be  tested  in  the 

^  A  complete  description  of  the  diagnosis  of  glanders  by  complement  fixation, 
giving  in  full  all  the  details,  will  be  found  in  Bull.  136,  Bureau  of  Animal  Indus- 
try, Apr.  7,  1911,  by  Mohler  and  Eichhorn. 


ANTHEAX  315 

manner  above  described.  All  animals  whose  serum  shows  complement 
fixation  should  be  destroyed  without  further  consideration.  After  the 
animals  have  been  killed  and  properly  disposed  of,  the  stable  should  be 
thoroughly  cleansed  and  disinfected.  All  other  horses  which  have  in^ 
any  way  been  associated  with  the  infected  animals  should  be  carefully 
watched  and  tested  again  after  three  weeks,  and,  should  there  be  no 
indication  of  the  disease  in  the  second  test,  the  stable  may  be  considered 
free  from  the  infection;  otherwise  the  infected  animals  should  be  de- 
stroyed and  the  tests  repeated  every  three  weeks  until  the  disease  has 
been  eliminated. 

The  eradication  of  glanders  from  a  stable  often  means  considerable 
loss  and  sometimes  a  sacrifice  of  valuable  animals,  but  it  is  only  through 
vigorous  measures  that  the  disease  may  be  controlled.  In  the  disin- 
fection and  cleansing  special  attention  should  be  paid  to  the  stalls, 
harnesses,  water  troughs,  bits,  food  containers,  curry  combs,  sponges, 
and  other  objects  exposed  to  the  infection,  which  is  eliminated  mostly 
in  the  secretions  from  the  mouth  and  nose.  The  common  drinking 
trough  for  horses  spreads  the  infection. 

The  personal  prophylaxis  of  glanders  in  man  depends  upon  the 
education  and  care  of  those  who  have  to  handle  horses.  In  working 
with  horses  known  to  be  infected  rubber  gloves,  disinfection,  and  other 
methods  of  protection  should  be  employed.  Special  care  should  be 
taken  to  prevent  the  spread  of  the  infection  through  the  discharges  or 
by  infected  fomites  from  human  cases.  Fatal  accidents  have  occurred 
in  laboratories  in  research  workers  handling  pure  cultures  of  B.  mallei. 


ANTHRAX 

Anthrax  belongs  to  that  group  of  diseases  which  occurs  primarily 
in  the  lower  animals  and  secondarily  in  man.  The  infection  is  found 
in  horses,  cattle,  sheep,  and  other  cloven-hoofed  animals,  and  may  be 
transmitted  experimentally  to  mice,  guinea-pigs,  rats,  and  rabbits.  Cold- 
blooded animals  and  birds,  as  well  as  dogs  and  swine,  are  refractory. 
Anthrax  has  a  world-wide  distribution;  Eussia  is  one  of  the  principal 
foci  of  infection. 

In  man  the  infection  may  enter  the  skin  (malignant  pustule)  or 
may  enter  the  lungs  (wool  sorters'  disease),  or  may  enter  the  diges- 
tive tract  and  produce  intestinal  lesions.  Human  anthrax  is  mostly  an 
industrial  disease  contracted  through  the  handling  of  skins,  hair  or 
animals.  In  anthrax  of  the  skin  the  infection  usually  enters  through 
slight  abrasions,  scratches,  or  small  wounds,  especially  on  the  forearm, 
hand,  or  face.  Most  of  the  cases  occur  in  butchers  or  persons  who 
have  to  handle  infected  carcasses.     The  spores  have  been  carried  to  the 


316  MISCELLANEOUS    DISEASES 

skin  by  flies ;  Schuberg  and  Kuhn  ^  have  shown  that  anthrax  may  be 
transferred  from  animal  to  animal  through  the  bite  of  the  stable  fly 
(Stomoxys  calcitrans).  Mitzmain  obtained  positive  results  with  the 
stable  fly  and  also  with  Tabanus  striatus.^ 

Wool  sorters'  disease,  or  anthrax  of  the  lungs,  appears  to  be  due 
to  the  inhalation  of  anthrax  spores.  It  is  observed  only  among  per- 
sons who  handle  skins  or  who  work  with  horse  hair  or  other  raw  materials 
from  animals  afflicted  with  anthrax. 

The  mode  of  transmission  in  intestinal  anthrax  is  through  meat 
from  an  anthrax  cadaver.  The  usual  heat  of  cooking  or  even  canning 
does  not  necessarily  kill  anthrax  spores.  Intestinal  anthrax  is  rare,  but 
when  it  does  occur  is  rapidly  fatal. 

Resistance. — The  anthrax  spore  is  exceedingly  resistant  to  heat  and 
external  influences,  such  as  dryness  and  sunlight,  and  also  to  germi- 
cidal agents.  Its  resistance  may  be  compared  to  the  tetanus  spore 
page  79. 

Immunity. — A  number  of  species  of  animals  have  a  natural  immu- 
nity to  anthrax,  and  an  artificially  acquired  imiuunity  may  be  induced 
in  cattle  or  sheep  through  the  injection  of  attenuated  cultures,  in  ac- 
cordance with  the  classical  method  of  Pasteur.  These  procedures  are 
not  applicable  to  man.  The  prevention  of  the  disease  in  man  must 
first  be  directed  to  a  suppression  of  the  disease  in  animals.  The  sick 
animals  should  be  isolated,  or,  better,  killed,  and  the  carcasses  burned 
or  buried  at  least  three  feet  deep.  The  carcasses  may  be  "tanked," 
that  is,  subjected  to  a  prolonged  exposure  to  steam  under  pressure. 
Tanks  for  this  purpose  are  found  in  all  the  larger  slaughter  houses. 
It  is  important  in  handling  the  body  of  an  animal  dead  of  anthrax 
not  to  open  it  or  shed  blood,  for  the  bacillus  does  not  produce  its  spore 
except  in  the  presence  of  oxygen,  that  is,  the  bacilli  are  mainly  in  the 
blood  and  internal  organs  and  will  not  sporulate  as  long  as  access  to  the 
air  is  prevented. 

The  neglect  of  precautions  in  disposing  of  anthrax  carcasses  favors 
the  spread  of  the  infection  through  the  activity  of  carrion  feeders.  Mor- 
ris ^  has  shown  that  buzzards  may  carry  infection  for  long  distances  and 
contaminate  clean  ground  or  water  through  contamination  on  their  feet 
and  beaks.  Dogs  discharge  anthrax  spores  in  their  feces  114  hours  after 
feeding  upon  an  anthrax  carcass. 

Prevention. — The  chief  preventive  measure  so  far  as  man  is  con- 
cerned is  the  disinfection  of  all  raw  material  in  those  trades  in  which 
horse  hair,  hides,  and  other  substances  liable  to  harbor  the  anthrax  spore 
are  handled.    Veterinary  surgeons  who  conduct  autopsies  upon  anthrax 

*Arbeiten  a.  d.  kaiserl.  Ges.-Amt.,  Bd.  XL.  Heft  2,  1912. 

=  Public  Health  Reports.  Jan.  9,  1914.  p.  75. 

2  Louisiana  Bull.  No.  136,  Agr.  Exp.  Sta.,  Nov.,  1912. 


FOOT-AND-MOUTH    DISEASE  317 

animals  should  exercise  unusual  precautions,  and,  if  practicable,  wear 
rubber  gloves. 

Ponder  ^  recommends  the  following  process  to  destroy  anthrax  in- 
fection in  hides :  The  dry  hides  are  placed  for  24  hours  in  a  "soak" 
which  is  made  to  contain  1  to  2  per  cent,  of  formic  acid  and  0.02  per 
cent,  of  bichlorid  of  mercury,  and  then  salting  them  with  sodium  chlorid. 
The  action  of  the  "soak"  is  to  swell  up  the  fibers  of  the  hide  by  causing 
them  to  absorb  water,  the  result  being  that  the  hide  returns  to  a  condition 
closely  resembling  that  in  which  it  was  taken  from  the  animal's  carcass. 
This  permits  the  bichlorid  of  mercury  to  permeate  and  exert  its  germi- 
cidal action. 

Hides  can  also  be  disinfected  by  immersion  in  hydrochloric  acid, 
1  per  cent.,  sodium  chlorid,  8  per  cent.,  for  6  hours  at  40°  C. ;  the  acid  is 
subsequently  neutralized  with  sodium  carbonate.  There  is  no  satisfactory 
method  of  disinfecting  hides  for  anthrax  without  injuring  the  hides  for 
tanning  purposes. 

Horse  hair  should  be  boiled.  Proper  ventilation  should  be  provided 
to  carry  off  the  dust  where  hair  and  wool  are  handled.  The  refuse  from 
tanneries  and  woolen  mills  should  be  properly  disposed  of;  otherwise  they 
may  infect  streams  or  fields  through  fertilizers. 


FOOT-AND-MOUTH   DISEASE 

Foot-and-mouth  disease  is  also  known  as  aphthous  fever,  epizootic 
catarrh,  and  eczema  contagiosa.  It  is  an  acute  and  highly  commu- 
nicable disease,  generally  confined  to  cloven-footed  animals,  and  char- 
acterized by  an  eruption  of  vesicles  on  the  mucous  membrane  of  the 
mouth  and  on  the  skin  between  the  toes  and  above  the  hoofs;  sometimes 
on  the  udders  or  other  parts  of  the  body.  The  vesicles  rupture,  leaving 
superficial  erosions  which  sometimes  develop  into  ulcers.  There  are  also 
salivation,  tenderness  of  the  affected  parts,  loss  of  appetite,  lameness, 
emaciation,  and  diminution  in  the  quantity  of  milk  secreted. 

Foot-and-mouth  disease  is  primarily  a  disease  of  cattle  and  sec- 
ondarily of  man.  It  affects  hogs,  sheep,  goats,  buffalo,  American  bison, 
camel,  chamois,  llama,  giraffe,  antelope,  and  even  dogs  and  cats  are  said 
to  occasionally  become  infected.     Horses  and  fowl  are  not  susceptible. 

The  disease  prevails  in  European  countries,  especially  Eussia,  also 
South  America,  Asia  and  Africa,  and  occasions  great  economic  loss.  The 
mortality  is  low;  the  serious  losses  depend  chiefly  upon  the  diminution 
of  the  milk  secretion  and  the  loss  of  flesh  in  the  affected  animals  as  well 
as  the  disturbances  of  quarantine.  It  occurs  as  widespread  epizootics 
especially  in  the  warm  season. 

^Lancet,  London,  Nov.  4,  CLXXXI,  No.  4601,  pp.   1247-1314. 


318  MISCELLANEOUS    DISEASES 

Foot-and-mouth  disease  has  appeared  in  the  United  States  only  on 
six  different  occasions— in  1870,  1880,  1884,  1903-3,  1908,  and  1914. 
Every  outbreak  on  American  soil  has  thus  far  been  followed  by  its  com- 
plete suppression  through  the  application  of  well-known  preventive  meas- 
ures, such  as  isolation,  destruction  and  burial  of  the  affected  herds,  disin- 
fection, restriction  of  the  movements  of  cattle,  and  a  systematic  inspection 
of  all  farms  in  the  infected  area  to  detect  cases  of  the  disease. 

Loffler  and  Frosch  ^  in  1898  showed  that  the  virus  will  pass  the 
finest  porcelain  filters.  This  was  the  first  ultramicroscopic  virus  dis- 
covered. The  specific  principle  is  contained  in  the  serum  of  the  vesicles ; 
in  the  saliva,  tears,  milk,  and  various  other  secretions  and  excretions; 
also  in  the  blood  until  the  eruption  comes  out,  then  it  disappears. 

No  definite  immunity  is  rendered  by  an  attack.  The  period  of  in- 
cubation is  variable,  usually  from  two  to  six  days  or  longer,  excep- 
tional instances  being  prolonged  to  fifteen  or  even  eighteen  days. 

The  disease  in  man  is  a  direct  counterpart  of  that  in  cattle.  The 
infection  is  transmitted  to  man  through  the  ingestion  of  raw  milk, 
buttermilk,  butter,  cheese,  and  whey  from  animals  suffering  with  foot- 
and-mouth  disease.  It  may  also,  though  more  rarely,  be  transmitted 
directly  from  the  salivary  secretions  or  other  infected  material  which 
gains  entrance  through  the  mucous  membrane  of  the  mouth.  It  is  doubt- 
ful whether  the  disease  can  be  transmitted  to  man  by  cutaneous  or  sub- 
cutaneous inoculation,  though  it  is  probable  that  the  infection  may  be 
communicated  if  the  virus  enters  the  blood  directly  through  wounds  of 
any  kind.  Children  are  most  frequently  infected  by  drinking  unboiled 
milk  during  the  time  in  which  the  disease  is  prevalent  in  the  neighbor- 
hood, while  persons  in  charge  of  diseased  animals  may  become  infected 
through  contact  with  the  affected  parts  or  by  milking,  slaughtering,  or 
caring  for  the  animals.  The  disease  is  usually  mild  in  man;  death j)rac- 
tically  never  results,  except  in  weakened  children,  and  then  from  sec- 
ondary complications, 

The  original  experiments  of  Loffler  and  Frosch,  as  well  as  recent 
experiments  which  have  been  made  in  Denmark  and  Germany,  indicate 
that  the  infection  is  destroyed  comparatively  readily  by  heat  or  the 
usual  antiseptics.  Milk  pasteurized  at  a  temperature  of  60°  C.  for  20 
minutes  is  safe. 

Foot-and-mouth  disease  has  a  special  interest  on  account  of  the  fact 
that  it  may  be  associated  with  vaccinia.  Vaccine  virus  has  been  known  to 
contain  the  infection  of  foot-and-mouth  disease.^  Glycerin  acts  as  a  pre- 
servative for  the  virus  of  foot-and-mouth  disease,  so  that  it  may  remain 
viable  in  glycerinated  vaccine  virus  a  very  long  time.    No  instance  of  the 

^Deut.  med.  Wochenschrift,   1898,  Vol.   24,  p.  80. 

"  "The  origin  of  the  Recent  Outbreak  of  Foot-and-Mouth  Disease  in  the 
United  States,"  by  Mohler  and  Rosenau,  Cir.  IJ/l,  Bureau  of  Animal  Industry, 
Dept.  of  Agriculture,  1909. 


MALTA    FEVEE  319 

transmission  of  foot-and-mouth  disease  to  man  through  vaccine  virus  has 
been  recorded,  and  it  is  doubtful,  in  view  of  the  known  facts,  whether 
it  is  possible  to  reproduce  the  disease  in  man  by  the  cutaneous  inoculation 
commonly  used  in  the  process  of  vaccination.  The  prevention  of  foot- 
and-mouth  infection  in  vaccine  virus  is  assured  through  federal  inspec- 
tion and  through  special  tests  (see  vaccine  virus,  page  20) .  Animals  may 
be  infected  directly,  as  by  licking,  and  in  calves  by  sucking,  or  indirectly 
by  fomites  such  as  infected  manure,  hay,  utensils,  drinking  troughs,  rail- 
way cars,  animal  markets,  barnyards,  and  pastures.  The  spread  of  the 
disease  is  due  largely  to  carrying  of  the  infection  on  the  hands  of  persons 
who  examine,  milk,  or  otherwise  come  in  contact  with  diseased  animals. 

The  prevention  of  foot-and-mouth  disease  consists  (1)  in  a  cattle 
quarantine,  to  keep  it  out  of  countries  where  it  does  not  exist;  (2)  in 
the  elimination  of  the  disease  in  cattle  through  isolation  of  infected 
herds,  destruction  and  burial  of  the  sick  animals,  and  disinfection; 
(3)  the  disease  in  man  may  be  avoided  by  care  in  the  selection  of  the 
animals  from  which  milk  is  taken  or  by  pasteurization  of  the  milk  when 
foot-and-mouth  disease  is  prevalent. 


MALTA   FEVER 

Malta  fever  is  a  general  infection  not  unlike  other  specific  bacteri- 
emias,  such  as  typhoid  fever.  It  is  caused  by  the  Micrococcus  meliteiv- 
sis,  discovered  by  Bruce  in  1887  during  the  earlier  days  of  bacteriology. 
Clinically  the  disease  is  characterized  by  profuse  perspiration,  constipa- 
tion, frequent  relapses  often  accompanied  by  pains  of  a  rheumatic  or 
neuralgic  character,  and  sometimes  swelling  of  the  joints  or  orchitis. 
Malta  fever  is  further  characterized  by  its  low  mortality  and  long- 
drawn-out  and  indefinite  duration.  It  prevails  especially  about  the  Medi- 
terranean basin. 

Gentry  and  Feren^augh  ^  have  recently  found  a  nest  of  malta  fever 
throughout  the  older  goat-raising  sections  of  Texas.  This  endemic  cen- 
ter embraces  an  area  approximately  300  miles  along  the  Eio  Grande 
extending  90  miles  to  the  north,  AH  the  cases  of  malta  fever  found 
have  occurred  in  territory  devoted  to  goat  raising,  and  all  the  patients 
there  gave  a  history  of  drinking  unboiled  goats'  milk  or  were  associated 
with  the  goat-raising  industry.  The  Micrococcus  melitensis  was  isolated 
from  several  of  the  cases. 

Modes  of  Transmission. — From  experimental  evidence  it  would  ap- 
pear that  the  infection  of  malta  fever  may  be  taken  in  through  wounds, 
the  mucous  membranes,  or  by  food  and  drink.  The  usual  mode  of  in- 
fection is  by  drinking  raw  goats'  milk.     The  Micrococcus  melitensis 

V.  A.  M.  A.,  Aug.  26,  Sept.  9,  Sept.  23,  Sept.  30,  1911. 


330  MISCELLANEOUS    DISEASES 

leaves  the  body  in  various  secretions  and  excretions.  Great  numbers 
of  the  cocci  in  pure  cultures  may  appear  in  the  urine.  The  milk  of 
goats  also  contains  the  virus.  All  the  secretions  from  the  body  must 
be  regarded  as  infectious  until  further  knowledge  on  the  subject  is  at 
hand.  In  man  the  coccus  may  be  isolated  from  the  spleen,  lymph  glands, 
bone  marrow,  and  mammary  glands.  In  goats  it  first  disappears  from 
the  blood,  then  the  spleen,  and,  last  of  all,  from  the  mammary  glands. 

Goats  are  susceptible  to  malta  fever  and  continue  to  discharge  the 
infection  in  the  milk  for  a  long  time.  The  disease  is  usually  contracted 
by  drinking  such  infected  milk.  While  this  is  the  common  mode  of 
infection,  occasional  cases  doubtless  arise  through  other  sources;  thus 
one  case  which  arose  in  England  is  supposed  to  have  been  conveyed 
from  son  to  father  by  using  a  clinical  thermometer  in  the  mouth  im- 
mediately after  its  use  by  the  patient.  Monkeys  may  readily  be  in- 
fected either  by  the  inoculation  of  pure  cultures  or  by  feeding  them. 
At  least  five  accidental  infections  have  occurred  in  bacteriological 
laboratories,  one  in  Washington.  Macfadyen  lost  his  life  from  a  labora- 
tory infection  with  the  Micrococcus  melitensis.  This  microorganism  has, 
therefore,  more  than  complied  with  all  the  requirements  of  Koch's  laws. 

There  has  long  been  a  suspicion  that  malta  fever  may  be  conveyed 
through  the  bite  of  an  ectoparasite.  In  fact,  Captain  Kennedy  was 
able  experimentally  to  infect  a  monkey  as  a  result  of  bites  of  mos- 
quitoes (Culex  pipiens)  which  had  fed  on  patients  suffering  with  malta 
fever.  This  probably  was  an  instance  of  mechanical  transference  of 
the  infection,  corresponding  in  all  respects  to  a  laboratory  inoculation 
with  fresh  virulent  material  from  a  hypodermic  syringe.  This  cannot 
be  a  frequent  way  by  which  the  infection  is  transmitted  in  nature,  for 
the  specific  organisms  are  found  in  small  numbers  in  the  peripheral 
blood  of  malta  fever  patients.  The  British  Commission  found  the  Micro- 
coccus melitensis  only  four  times  from  a  total  of  896  mosquitoes  studied. 

From  the  fact  that  the  micrococcus  may  be  successfully  introduced 
either  by  ingestion,  or  by  inoculation,  or  through  the  mucous  mem- 
branes, it  is  evident  that  occasionally  cases  may  receive  their  infection 
through  a  great  variety  of  means,  such  as  insect  bites  and  other  wounds, 
infected  food,  and  the  various  modes  of  contact  infection.  Contact 
infection,  however,  probably  plays  a  minor  role,  for  there  is  evidence 
that  the  disease  is  not,  as  a  rule,  directly  transmitted  from  the  sick  to 
the  well. 

There  is  also  experimental  evidence  to  show  that  monkeys  can  be 
infected  by  dry  dust  artificially  contaminated  with  cultures  of  the  Micro- 
coccus melitensis.  The  path  of  entrance  may  be  through  the  nares, 
throat,  respiratory  passages,  or  alimentary  canal.  Dry  dust  contaminated 
with  the  urine  of  cases  of  malta  fever  has  given  rise  to  infection  in  goats 
but  not  in  monkeys.     The  experience  gained  during  tlie  work  performed 


MALTA    FEVER  321 

in  Malta  during  1904  and  1905  has  convinced  Horrocks  that  men  are 
more  susceptible  than  monkeys  and  goats.  Shaw's  work  on  ambulatory 
cases  of  malta  fever  among  Maltese  has  also  shown  that  opportunities 
for  the  creation  of  infected  dust  are  plentiful  in  ]\Ialta.  Infected  dry 
dust  as  a  mode  of  transmission  cannot,  therefore,  be  discarded,  but,  as  a 
matter  of  fact,  it  probably  seldom  occurs. 

Goats'  Milk  and  Malta  Fever. — AVe  are  indebted  to  the  six  reports 
of  the  British  Commission  for  the  investigation  of  Mediterranean  fever 
(1905-1907)  for  the  fact  that  malta  fever  is  chiefly  spread  through  goats' 
milk.  Before  the  researches  of  this  commission  the  common  mode  of 
infection  was  not  definitely  known. 

The  usual  source  of  milk  in  Malta  is  the  goat.  The  udders,  which 
are  abnormally  long,  often  touch  the  ground  and  are  very  liable  to  be 
soiled.  It  was  first  shown  by  Zammit  in  the  report  of  1905  that  goats 
could  be  infected  by  feeding  them  with  the  Micrococcus  melite^isis. 
In  the  same  year  Major  Horrocks  discovered  the  Micrococcus  melitensis 
in  the  milk  of  an  apparently  healthy  goat.  Further  studies  showed  that 
one  or  more  healthy  goats  in  every  herd  were  excreting  the  Micrococcus 
melitensis  in  their  milk  and  urine,  and  that  about  50  per  cent,  of  the 
goats  reacted  positively  when  examined  by  serum  agglutination  tests.  All 
the  available  evidence  points  to  their  food  as  the  main  vehicle  of  infection 
in  goats.  The  young  goats,  of  course,  are  infected  through  their  mother's 
milk,  florrocks  and  Kennedy  consider  that  10  per  cent,  of  the  goats 
supplying  milk  to  various  parts  of  Malta  excrete  the  Micrococcus  meliten- 
sis in  thei'r  milk.  The  excretion  of  the  specific  microorganism  may 
continue  steadily  for  three  months  without  any  change  occurring  in  the 
physical  character  or  chemical  composition  of  the  milk  and  without  the 
animal  exhibiting  any  signs  of  ill  health.  On  the  other  hand,  the  excre- 
tion of  the  Micrococcus  melitensis  in  the  milk  may  be  intermittent,  ap- 
pearing for  a  few  days  and  then  disappearing  for  a  week  or  more. 

Major  Horrocks  in  Report  A"o.  5  of  the  British  Commission  shows 
a  direct  relation  between  the  number  of  goats  in  Gibraltar  to  the  num- 
ber of  cases  of  malta  fever.  With  the  reduction  in  the  number  of  goats 
in  Gibraltar  there  was  also  a  decrease  in  the  number  of  cases,  so  that 
finally,  when  the  number  of  goats  had  decreased  to  about  200  in  1905, 
malta  fever  had  practically  disappeared. 

The  story  of  the  steamship  Joshua  Nicholson  is  instructive  in  show- 
ing the  relation  between  goats'  milk  and  malta  fever  in  man.  Sixty- 
one  milch  goats,  all  healthy  in  appearance  and  good  milkers  (many 
being  prize  animals),  and  four  billygoats  were  shipped  on  board  the 
cargo  steamer  Joshua  Nicholson  August  19,  1905,  at  Malta  for  passage 
to  the  United  States  via  Antwerp.  Many  of  the  ship's  company  partook 
freely  of  the  milk.  The  officers  drank  "mixed"  milk  collected  in  a  large 
vessel;  the  members  of  the  crew  each  obtaining  the  "whole"  milk  from 
12 


333  MISCELLANEOUS    DISEASES 

one  goat  in  his  own  separate  pannikin.  Subsequent  bacteriological  exam- 
ination resulted  in  the  recovery  of  the  Micrococcus  melitensis  from  the 
milk  of  several  of  the  goats.  Of  23  men  on  board  the  steamer  who  drank 
the  goats'  milk  on  one  or  more  occasions,  no  evidence  whatever  is  avail- 
able as  to  13,  while  of  the  remaining  10,  9  suffered  from  febrile  attacks, 
5  of  them  yielding  conclusive  evidence  of  infection  with  the  Micrococcus 
melitensis. 

Resistance. — The  Micrococcus  melitensis  is  readily  destroyed  by  heat. 
I  have  shown  that  60°  C.  for  20  minutes  is  sufficient  to  destroy  this 
organism  in  milk  and  provides  at  the  same  time  a  liberal  margin  of 
safety.  It  is  not  destroyed  at  55°  for  a  short  time,  but  succumbs  in  one 
hour;  the  majority  die  at  58° ;  at  60°  all  are  killed.  Phenol,  1  per  cent., 
destroys  the  coccus  in  15  minutes.  While  this  micrococcus  shows  a  com- 
paratively feeble  resistance  against  heat  and  the  ordinary  germicides,  it 
shows  a  remarkable  resistance  to  dryness,  for  it  may  remain  alive  in 
this  state  for  months. 

The  micrococcus  grows  well,  but  slowly,  upon  artificial  culture  media. 
Visible  colonies  do  not  appear  until  about  the  fifth  day.  It  may  be  kept 
alive  indefinitely  by  transplanting  to  subcultures  at  frequent  intervals. 
Exceedingly  high  agglutinating  power  develops  in  persons  suffering  with 
malta  fever — sometimes  as  high  as  1-100,000.  In  such  cases  the  pro- 
agglutinoid  zone  may  appear,  that  is,  the  serum  may  refuse  to  agglutinate 
in  low  dilutions,  such  as  1-100,  but  agglutinate  actively  in  higher  dilu- 
tions, such  as  1-1,000. 

Prevention. — Our  knowledge  of  the  cause  and  modes  of  traiismission 
of  malta  fever  makes  the  prevention  of  this  disease  a  comparatively 
simple  problem.  The  infection  must  first  be  eliminated  in  the  goats. 
Until  this  is  done  goats'  milk  should  be  pasteurized.  Patients  having  the 
disease  should  be  treated  upon  the  same  principles  laid  down  for  typhoid 
fever,  in  order  to  prevent  the  spread  of  the  infection  through  food, 
fomites,  and  indirect  contact.  Convalescents  should  not  be  released  until 
the  micrococcus  has  disappeared  from  the  urine.  General  sanitary  meas- 
ures, such  as  the  suppression  of  flies  and  mosquitoes,  allaying  dust,  and 
the  promotion  of  general  cleanliness,  should  not  be  neglected. 


LEPROSY 

Leprosy  is  a  contagious  disease  in  the  sense  that  it  is  probably  always 
communicated  directly  from  the  sick  to  the  well,  but  prolonged  and 
Intimate  association  with  a  leper  ordinarily  seems  necessary  to  contract 
the  infection.  The  degree  of  the  contagiousness  varies  very  much,  de- 
pending upon  conditions  not  well  understood,  but  it  is  plain  that  leprosy 
shows  little  tendency  to  spread  in  any  of  the  more  highly  civilized  nations 


LEPEOSY  323 

practicing  personal  cleanliness  and  enjoying  the  benefits  of  modern  sani- 
tation. When  the  standards  of  living  improve,  the  disease  tends  to 
diminish.  The  fear  of  the  disease  is  almost  without  parallel.  Leprosy 
prevailed  in  epidemic  form  in  Europe  in  the  middle  ages,  but  the  disease 
has  disappeared  from  central  Europe,  remaining  only  upon  the  fringe 
of  the  continent,  in  Norway,  Sweden,  Spain,  Italy,  Greece,  Turkey,  Rus- 
sia, and  Finland.  There  are  a  considerable  number  of  cases  of  local 
origin  in  Austria  (Bosnia  and  Herzegovina),  and  a  few  in  Germany 
(Memel),  France,  and  Bulgaria.  It  is  estimated  that  there  are  from 
5,000  to  6,000  lepers  in  the  Philippine  Islands,  and  there  are  many  cases 
in  China  and  Japan.  In  India  the  i3ensus  of  1910  shows  an  increase 
from  100,000  to  110,000  during  the  previous  ten  years.  Leprosy  is  also 
on  the  increase  in  southern  Africa  (Bayou)  ;  in  Basutuland  alone  it  is 
estimated  (1912)  that  there  are  3,000  lepers,  in  a  population  of  about 
270,000.  The  greatest  incidence  is  found  among  the  natives  of  the 
Hawaiian  Islands,  where  one  in  every  30  or  40  have  the  disease.  Leprosy 
was  introduced  into  the  Hawaiian  Islands  about  1859,  and  there  found 
conditions  particularly  favorable  for  spread.  Leprosy  was  unknown  in 
the  Hawaiian  Islands  before  1848.  In  40  years  close  to  5,000  cases  were 
repotted.  A  Government  Commission  in  1902  ^  took  a  census  of  the 
lepers  in  the  United  States  and  found  278.  Of  these  145  were  born  in 
the  United  States  and  186  probably  contracted  the  disease  in  the  United 
States.  Of  the  entire  number  72  of  the  cases  were  isolated  and  205  were 
at  large.  Brinckerhoff  again  studied  the  prevalence  of  leprosy  in  the 
L^nited  States  in  1909  and  found  139  cases.  The  official  figures  for  1912 
are  146.^  Although  these  numbers  represent  only  the  cases  officially 
known,  it  is  evident  that  the  disease  is  not  on  the  increase  in  our  country 
and  that,  while  it  may  be  contracted  here,  it  is  "contagious"  with  great 
difficulty.  There  are  three  foci  of  leprosy  in  the  United  States:  one 
among  the  Scandinavians  in  the  region  of  the  Great  Lakes,  another 
among  the  Orientals  on  the  Pacific  Coast,  and  the  third  on  the  Gulf 
Coast,  particularly  in  liouisiana  and  Florida,  where  most  of  the  cases 
are  native  born.  According  to  the  most  recent  figures  available  (1914) 
the  number  of  cases  in  isolation  in  our  insular  possessions  is  as  follows : 
Hawaii,  689;  Porto  Rico,  28;  Philippine  Islands,  3,439;  the  Canal  Zone, 
7.  The  lepers  in  Guam,  18  in  number,  were  transferred  to  the  Philippine 
leper  colony  at  Culion  during  1913.     It  is  known,  however,  that  many 

^  White,  Vaughan,  and  Rosenau,  Document  No.  269,  57tli  Congress,  1st  Ses- 
sion, 1902. 

^Complete  returns  from  only  18  states.  The  incompleteness  of  the  official 
returns  is  indicated  by  the  fact  that  New  York  State  acknowledged  only  5  cases, 
whereas  at  a  recent  medical  meeting  more  than  that  number  of  cases  were 
shown  in  New  York  City  alone.  Tlie  laws  concerning  leprosy  vary  in  the  differ- 
ent States.  New  York,  for  example,  has  no  stringent  laws  and  there  are  40  or 
50  cases  at  large  in  New  York  City.  Pennsylvania  and  Massachusetts,  on  the 
other  hand,  enforce  strict  segregation. 


324  MISCELLANEOUS    DISEASES 

cases  escape  tabulation  in  the  official  returns.  There  are  perliaps  a  mil- 
lion lepers  in  the  world.  About  50  p(!r  cent,  more  males  are  affected 
than  females. 

'i'lie  cause  of  leprosy  is  the  Bacillus  leprae  discovered  by  Armauer- 
Hansen  in  1874.  The  bacillus  of  leprosy  resembles  the  bacillus  of  tu- 
berculosis in  many  respects.  It  stains  more  readily  and  decolorizes  some- 
what more  readily  than  the  tubercle  bacillus.  It  differs  from  the  tubercle 
bacillus  in  that  it  grows  with  difficulty  on  artificial  culture  media  and  is 
much  less,  if  at  all,  pathogenic  for  the  lower  animals.  Further,  lepra 
bacilli  are  usually  found  in  dense  clusters  and  in  much  greater  numbers 
within  the  cells  than  is  the  case  with  the  tubercle  bacillus. 

The  bacillus  of  leprosy  grows  with  difficulty  upon  artificial  culture 
media.  For  years  it  has  evaded^  all  attempts  until  Clegg^  in  1909  suc- 
ceeded in  cultivating  an  acid-fast  bacillus  in  symbiosis  with  amebae  and 
cholera  vibrio  upon  plain  agar  and  weakly  nutrient  agar.  Clegg  based 
his  work  upon  the  belief  that  the  leprosy  bacillus  derives  its  nutrition 
from  the  products  of  the  tissue  cells  in  which  it  is  mainly  to  be  seen  in 
leprosy  lesions.  These  results  have  been  confirmed  by  Currie,  Brincker- 
hofl:,  and  Holman  in  Hawaii  and  by  Duval  in  New  Orleans. 

The  latter  has  shown  that  the  amebas  are  not  essential  and  that 
other  microorganisms  may  replace  the  cholera  vibrio  or  that  the  addition 
of  certain  amino  acids  (tryptophane  and  cystein)  to  the  media  is  suffi- 
cient to  bring  about  the  necessary  conditions  for  growth.  There  is  no 
satisfactory  evidence  that  any  of  the  cultures  isolated  will  reproduce  the 
disease  in  experimental  animals. 

Immunity. — There  is  no  racial  immunity  to  leprosy.  The  white 
races  suffered  severely  during  the  middle  ages.  Malays,  Mongols  and 
Negroes  now  appear  most  liable  to  the  infection,  perhaps  on  account  of 
their  mode  of  life.  The  disease  is  remarkable  for  its  prolonged  period 
of  incubation  and  its  chronic  course.  The  lesions  may  not  be  noticed 
until  20  or  more  years  after  exposure.  The  disease  is  not  usually  recog- 
nized until  at  least  7  years  have  elapsed.  These  facts  indicate  that  the 
body  must  possess  a  high  degree  of  resistance  to  this  infection.  So  far 
as  known,  man  is  the  only  animal  subject  to  leprosy  under  natural  condi- 
tions. Inoculation  experiments  into  lower  animals  have  recently  been 
reported  in  the  guinea-pig  (Clegg)  ;  the  Japanese  dancing  mouse  (Su- 
gai)  ;  and  the  monkey  (Duval).  It  is  questionable,  however,  whether 
the  disease  has  been  reproduced  in  the  lower  animals. 

Leprous  material  has  been  inoculated  into  human  beings  by  Daniel- 
son,  Profeta,  Cagnina  and  Bargilli  with  negative  results.  These  experi- 
ments demonstrate  the  resistance  of  the  body  to  small  quantities  of  the 
virus.     In  Arning's  well-known  case  of  the  convict  Keanu,  who  was 

^  The  Philippine  Jour,  of  Science,  Vol.  IV,  No.  77,  Apr.,  1909.  Public  Health 
Bull.  Jo,  j7)  >Sf?pt.,  1911. 


LEPEOSY  335 

pardoned  on  condition  that  he  allow  himself  to  be  inoculated  with 
leprosy,  the  disease  did  develop,  but  the  case  is  somewhat  spoiled  by  the 
fact  that  the  man  had  lepers  among  his  relatives,  and  was  in  contact 
with  them  before  and  after  inoculation. 

Rat  Leprosy. — There  is  a  disease  among  rats  which  is  a  close  coim- 
terpart  of  leprosy  in  man.  It  occurs  naturally  in  the  Mus  norvegicm 
and  may  be  transferred  by  inoculation  to  the  more  tractable  laboratory 
white  rat.  The  disease  was  first  observed  by  Stenfansky  in  1903  in 
Odessa.  In  the  same  year  Eabinowitsch  found  the  disease  among  the 
rats  of  Berlin,  and  Dean  in  1903  discovered  the  disease  independently 
in  London,  and  in  a  later  publication  (1905)  reported  success  in  trans- 
ferring the  infection  by  artificial  inoculation.  Since  then  rat  leprosy 
has  been  found  by  Tidswell  in  the  rats  of  Sydney,  Australia ;  by  Kitasato 
in  Japan;  Marchoux  and  Leboeuf  in  Paris,  and  the  English  Plague 
Commission  observed  the  disease  among  the  rats  in  India.  Wherry  and 
McCoy  found  a  number  of  cases  among  the  rats  caught  in  San  Francisco, 
California. 

The  proportion  of  rats  infected  with  rat  leprosy  in  different  localities 
varies  greatly.  Thus  in  Odessa  and  Paris  from  4  to  5  per  cent.,  in  San 
Francisco  0.2  per  cent.,  and  in  Sydney  only  0.001  per  cent.  Currie 
failed  to  find  leprosy  among  the  rats  of  Honolulu.  The  fact  that  the 
infection  is  absent  among  the  rats  of  Honolulu  and  present  among  the 
rats  in  Berlin  is  evidence  that  it  plays  no  part  in  the  epidemiology  of  the 
human  disease. 

Leprous  rats  in  a  late  stage  of  the  disease  are  usually  recognized 
by  the  presence  of  patchy  alopecia  associated  with  cutaneous  and  sub- 
cutaneous nodules  which  may  or  may  not  be  the  site  of  open  iilcers; 
only  in  advanced  cases  are  the  internal  organs  affected.  The  diagnosis 
is  readily  confirmed  by  microscopic  examination  of  a  smear  from  an 
ulcer  or  a  nodule,  which  will  show  the  acid  and  alcohol  fast  bacillus  of 
the  disease  in  enormous  numbers,  and  mostly  in  the  cells. 

Currie  ^  has  recently  shown  that  rats  may  infect  each  other  by  con- 
tact, also  that  bacilli  of  rat  leprosy  may  often  by  demonstrated  in  the 
heart's  blood  of  infected  rats.  Currie  and  also  Marchoux  and  Sorel  had 
no  difficulty  in  demonstrating  the  presence  of  acid-fast  bacilli  in  mites 
contained  on  the  bodies  of  rats  when  the  latter's  heart's  blood  contained 
the  microorganisms.  -The  fact  that  these  mites  so  frequently  contain  the 
bacilli  naturally  leads  to  the  suspicion  that  they  may  be  one  of  the  means 
of  transmitting  the  disease  from  rat  to  rat,  but  up  to  the  present  time  no 
positive  evidence  has  been  adduced  that  such  is  the  case. 

Mezincescu,  using  rat  leprosy  antigen,  obtained  complete  complement 
fixation  with  human  leprosy  serum;  this  confirmed  Slatineau's  work. 

^U.  S.  Pub.  Health  and  Mar.  Hosp.  Ser.,  Pub.  Health  Bull.  No.  50.  Oct., 
1911. 


326  MISCELLANEOUS    DISEASES 

Schmitt  obtained  positive  results  with  syphilitic  antif^en  and  human 
leprosy  serum  and  numerous  other  observers  have  with  different  antigens 
and  serum  obtained  positive  reactions  and  thus  have  shown  the  simi- 
larity of  the  two  diseases.  The  bacillus  has  been  cultivated  by  Dean, 
Hollman,  Chapin,  and  others. 

In  this  leprosy-like  disease  of  rats  we  have  an  infection  which  closely 
resembles  leprosy  in  man.  The  fact  that  the  infection  may  be  propagated 
in  a  laboratory  animal  permits  of  its  investigation,  and  it  is  assumed  that 
the  further  studies  now  being  made  upon  rat  leprosy  will  throw  much 
light  upon  the  modes  of  transmission  and  control  of  the  human  disease. 

Modes  of  Transmission. — The  leprosy  bacillus  is  found  in  all  the 
lesions  of  the  disease — ithe  nodules  on  the  skin  and  mucous  membranes, 
in  the  spleen,  liver,  and  testicles — in  fact,  in  all  the  internal  lesions. 
In  the  anesthetic  type  the  bacilli  are  found  in  the  cells  of  the  spinal 
cord  and  brain  and  also  in  the  peripheral  nerves.  Leprosy  bacilli  may 
also  be  found  in  the  circulating  blood  during  the  febrile  attacks.  Fre- 
quently they  are  in  the  endothelial  or  in  the  white  blood  cells.  The  lep- 
rosy bacillus  leaves  the  body  from  any  of  the  lesions  that  are  broken 
down.  From  the  degenerated  nodules  of  the  skin  or  mucous  membranes 
they  are  discharged  in  enormous  numbers.  If  we  may  depend  upon 
microchemical  evidence,  it  appears  that  most  of  these  bacilli  are  probably 
dead.  Leprosy  bacilli  also  occasionally  appear  in  the  feces  and  urine. 
They  occur  in  the  expectoration  from  lesions  in  the  throat  which  are 
common. 

There  is  some  doubt  as  to  just  how  the  leprosy  bacillus  enters  the 
body,  whether  through  wounds  of  the  skin  or  through  the  mucous 
membrane  of  the  nose  and  throat  or  through  the  digestive  tract,  or 
possibly  during  coitus.    Insects  are  also  suspected. 

It  may  be  definitely  stated  that  leprosy  is  not  due  to  the  eating  of 
any  particular  food,  such  as  fish.  This  theory  has  been  stoutly  main- 
tained by  Jonathan  Hutchinson.  There  is  no  satisfactory  evidence  in 
support  of  the  fish  theory  and  many  facts  against  it.  One  thing  is  j^lain, 
and  that  is,  leprosy  is  not  contracted  from  any  of  the  lower  animals,  but 
is  an  infection  which  in  all  cases  passes  rather  directly  from  man  to  man. 

The  suspicion  that  parasitic  insects  may  play  some  role  in  the  trans- 
mission of  leprosy  has  existed  for  some  time.  The  evidence  is  reviewed 
by  Nuttall,^  who  says :  "It  appears  that  Linnaeus  and  Eolander  consid- 
ered that  Chlorops  (musca)  leprae  was  able  to  cause  leprosy  by  its  bite." 
Blanchard  and  Corrodor  tell  of  flies  in  connection  with  leprosy.  Flies 
frequently  gather  in  great  numbers  on  the  leprous  ulcers  and  then  visit 
and  bite  other  persons.  An  observation  by  Boeck  of  the  presence  of 
Sarcoptes  scahei  in  a  case  of  cutaneous  leprosy  led  Joly  to  conclude  that 
these  parasites  might  at  times  serve  as  carriers  of  the  infection.    Pediculi 

^  Johns  Hopkins  Hospital  Reports,  1000,  VIII,  p.  1. 


LEPEOSY  327 

are  usually  present  among  the  poor  classes  in  Algeria,  which  furnish  the 
greater  numher  of  lepers.  Sommer  of  Buenos  Aires  expresses  the  belief 
that  mosquitoes  act  as  active  agents  in  the  spread  of  leprosy  in  warm 
countries.  Carrasquillo  of  Bogota  found  the  bacillus  of  Hansen  in  the 
intestinal  contents  of  flies.  The  British  Leprosy  Commission  investigated 
the  possible  role  played  by  insects  with  entirely  negative  results.  Wherry 
studied  the  occurrence  of  lepra-like  bacilli  in  certain  flies  and  their 
larva.  He  found  that  the  fly  Chlorops  vomUoria  took  up  enormous  num- 
bers of  lepra  bacilli  from  the  carcass  of  a  leper  rat  and  deposited  them 
with  their  feces,  but  the  bacilli  apparently  do  not  multiply  in  the  flies, 
as  the  latter  are  clear  of  bacilli  in  less  than  48  hours.  Larvae  of  Chlorops 
vomitoria  hatched  out  in  the  carcass  of  a  leper  rat  become  heavily  infested 
with  lepra  bacilli.  If  such  larvae  are  removed  and  fed  on  iminf ected  meat 
they  soon  rid  themselves  of  most  of  the  lepra  bacilli.  A  fly,  Musca  domes- 
tical caught  on  the  face  of  a  human  leper  was  found  to  be  infested  with 
lepra-like  bacilli.  The  horrid  sight  of  flies  swarming  about  leprous 
lesions  and  the  nostrils  of  leprous  beggars  is  well-known  to  travelers  in 
eastern  countries.  Lepra-like  bacilli  have  been  found  in  bedbugs  and 
these  insects  have  long  been  associated  with  the  spread  of  the  disease. 

The  evidence  bearing  on  the  possible  role  of  insects  in  the  transmis- 
sion of  leprosy  may  be  classified  as  purely  presumptive  evidence  based 
upon  analogy,  or  as  evidence  based  simply  upon  the  finding  of  acid-fast 
bacilli  in  certain  insects.  It  must  be  plain  that  the  simple  taking  up  of 
parasites  by  an  insect  does  not  necessarily  imply  that  the  insect  plays  a 
role  in  its  transmission  from  one  host  to  another.  Further,  not  all  acid- 
fast  bacilli  are  leprosy  bacilli.  It  cannot  be  denied  that  leprosy  may  be 
one  of  the  insect-borne  diseases;  the  final  verdict  will  depend  upon 
further  studies. 

A  great  majority  of  lepers  at  some  time  in  the  disease  have  lepra 
bacilli  in  their  nasal  secretions.  The  importance  of  the  nose  in  leprosy 
was  brought  into  prominence  at  the  First  International  Leper  Confer- 
ence in  1897  by  the  work  of  Sticker,  who  made  sweeping  statements 
concerning  the  nose  as  the  site  of  the  primary  lesion  and  the  danger 
of  nasal  secretions  in  transmitting  the  disease.  Jeanselme  and  Laurans 
(1895),  Gerber  (1901),  Werner  (1902),  Sheroux  (1903),  and  others 
have  shown  the  frequency  with  which  the  bacilli  of  leprosy  appear  in 
the  nasal  secretions  and  the  importance  of  the  nose  as  a  site  of  leprous 
lesions.  Sticker  cites  a  five-year-old  child  of  leprous  parents  seen  by 
him  in  India  with  an  ulcer  on  the  right  side  of  the  nasal  septum  which 
contained  lepra  bacilli  and  was  the  only  lesion  of  the  disease  present  in 
the  case.  Plumert  (1903)  mentions  the  finding  of  lepra  bacilli  in  the 
nasal  secretions  of  persons  in  intimate  family  contact  with  advanced 
cases  of  leprosy.  The  individuals  in  question  showed  no  other  evidence 
of  the  disease.     Falkao  observed  epistaxis  associated  with  small  ulcers 


328  MISCELLANEOUS    DISEASES 

on  the  nasal  septum  of  descendants  of  lepers,  und  lepra  bacilli  were 
found  in  the  crusts  from  these  ulcers.  The  results  of  Sticker,  Plumert, 
and  Falkao  would  indicate  that  in  the  early  stages  of  the  disease  the  nose 
is  frequently  the  site  of  a  lesion  discharging  lepra  bacilli.  Brinckerhoff 
and  Moore,  however,  who  made  a  careful  study  of  this  question  in 
Honolulu,  point  out  that  most  of  the  studies  upon  the  importance  of 
the  nose  in  leprosy  have  been  made  upon  relatively  advanced  cases  of 
the  disease.  They  found  the  nose  frequently  the  seat  of  infection  when 
the  disease  is  well  developed,  but  practically  never  as  a  primary  or 
incipient  lesion.  If  the  nose  were  the  usual  seat  of  the  primary  lesion 
in  leprosy,  it  would  indicate  that  the  infection  is  carried  there  upon 
the  finger. 

Hollmann  studied  500  persons  in  the  Hawaiian  Islands  suffering  with 
a  recognizable  form  of  leprosy  for  periods  varying  from  three  months  to 
twenty-five  years,  and  found  410  with  lesions  of  the  nasal  mucous  mem- 
brane and  only  90  in  which  such  lesions  were  absent. 

Bearing  upon  the  contagiousness  of  leprosy  we  have  Kitasato's  statis- 
tics from  Japan  showing  that  the  children  of  lepers  become  leprous 
in  a  proportion  of  only  7.05  per  cent,  of  the  total.  Matrimonial  infection 
was  proven  in  3.8  per  cent,  of  cases,  while  persons  living  under  the 
same  roof  showed  a  proportion  of  only  2.7  per  cent.  Brothers  and  sisters 
infect  each  other  in  a  ratio  of  4.2  per  cent.  These  figures  roughly  corre- 
spond to  Sand  and  Lies'  studies  in  Norway. 

Jeanselme  ^  reports  observations  confirming  the  Chinese  and  Japanese 
belief  that  leprosy  spreads  largely  by  sexual  contact.  Jeanselme  found 
"leprous"  urethritis  set  up  by  lepromata  which  invaded  the  navicular 
fossa.  He  further  states  that  myriads  of  acid-fast  bacilli  may  be  found 
in  a  drop  of  pus  which  may  be  squeezed  from  the  meatus  under  this  con- 
dition. 

It  is  sufficient  for  practical  prevention  to  know  that  leprosy  is  spread 
mainly  by  direct  contact  and  perhaps  occasionally  by  indirect  contact 
with  persons  suffering  with  the  disease.  In  a  case  observed  in  northern 
Germany  one  girl  directly  and  indirectly  infected  28  people.  Leprosy  is 
most  prevalent  under  conditions  of  personal  and  domestic  uncleanliness 
and  overcrowding,  especially  where  there  is  close  and  protracted  associa- 
tion between  the  leprous  and  the  non-leprous.  There  are  instances  on 
record  in  which  persons  have  contracted  the  infection  after  a  stay  of 
only  a  day  or  two  in  a  leprous-ridden  area.  There  is  no  evidence  that 
leprosy  is  inherited.  Children  born  of  leprous  parents  do  not  as  a  rule 
develop  the  disease  if  removed  at  once.  The  occurrence  of  several  cases 
in  a  single  family  is  doubtless  due  to  "contact."  The  danger  of  infection 
from  leprous  persons  is,  of  course,  greater  when  there  is  a  discharge  from 
the  lesions  of  the  skin  and  mucous  membranes. 

^  Bull,  de  la  Societe  de  Medecine  Exotique,  No.  7,   1914, 


LEPROSY  329 

Prevention. — The  prevention  of  leprosy  depends  almost  entirely 
upon  isolation,  care  of  the  infected  discharges,  personal  cleanliness,  and 
sanitary  surroundings.  The  disease  is  transmitted  with  difficulty,  how- 
ever ;  doctors,  nurses,  sisters  of  charity,  ward  tenders,  and  others  directly 
exposed  in  leprosaria  sometimes  become  infected.  Xotable  examples  have 
been  Father  Damien  at  Molokai,  Hawaii,  and  Father  Bogliolo  in  New 
Orleans,  Sir  George  Turner  in  Pretoria,  and  Miss  Mary  Eeed  in  India. 
About  5  per  cent,  of  the  healthy  consorts  of  lepers  become  infected  at  the 
Hawaiian  settlement.  Evidently  close,  prolonged  and  intimate  contact 
is  ordinarily  necessary  to  contract  the  infection. 

For  the  control  of  leprosy  the  most  important  administrative  meas- 
ure is  to  segregate  the  lepers  in  settlements  or  asylums.  Segregation 
also  entails  proper  treatment  and  humane  care.  Compulsory  notification 
of  every  case  of  leprosy  should  be  enforced,  if  for  no  other  reason  than 
to  keep  track  of  the  disease  and  to  know  whether  it  is  on  the  increase. 
The  leprosaria  should  be  inviting  and  should  contain  all  modern  improve- 
ments for  the  care  and  treatment  of  the  disease.  Leprosy  is  by  no  means 
invariably  fatal.  In  the  United  States,  where  there  are  only  a  few 
hundred  lepers,  the  Government  should  establish  a  national  leprosarium 
conducted  upon  the  principles  of  a  modern  sanitarium  for  tuberculosis. 
To  require  each  state  to  provide  suitable  accommodations  to  segregate 
its  few  lepers  is  economically  wasteful.  It  is  claimed  that  the  decrease 
in  leprosy  in  Europe  during  the  middle  ages  was  due  in  large  part  to  the 
segregation  of  the  lepers  in  leprosaria,  which  at  one  time  numbered 
20,000.  On  the  other  hand,  the  value  of  segregation  is  disputed  because 
many  lepers  were  at  large;  however,  they  were  not  allowed  in  churches 
or  market  places,  and  were  branded  as  "unclean"  by  a  distinctive  dress 
and  were  further  required  to  make  their  presence  known  by  a  bell  or 
clapper.  Great  numbers  of  lepers  were  swept  away  by  the  bubonic  plague 
during  these  times.  As  a  rule,  only  the  advanced  cases  are  detected  and 
isolated.  In  the  Philippines  segregation  of  all  discoverable  cases  reduced 
new  admissions  by  90  per  cent.  In  some  of  the  British  colonies  in  South 
Africa,  where  only  about  half  of  the  leper  population  is  segregated,  the 
rate  of  admission  has  remained  constant  for  the  last  ten  years.  Segrega- 
tion in  the  Hawaiian  Islands  has  so  far  had  no  effect  upon  the  prevalence 
of  the  disease.  There  are  factors  in  the  control  of  leprosy  not  yet  imder- 
stood.  As  soon  as  a  country  becomes  well  to  do  and  adopts  the  daily  tidi- 
ness incident  to  modern  civilized  life,  leprosy  dies  out. 

There  can  be  little  objection  in  a  country  such  as  ours,  where  leprosy 
shows  slight  tendency  to  spread,  to  give  a  clean  leper  his  freedom. 
There  is  no  more  danger  from  a  leprosy  patient  with  clean  personal 
habits,  who  exercises  care  concerning  the  discharges  from  the  lesions, 
than  there  is  from  an  open  case  of  tuberculosis  of  the  glands  of  the  neck. 
The  purely  nerve  cases,  particularly  if  there  are  no  ulcerations,  may 


330  MISCELLANEOUS    DISEASES 

properly  be  given  a  greater  degree  of  liberty  tban  those  with  nodular 
manifestations. 

The  national  quarantine  regulations  forbid  the  landing  of  an  alien 
leper.  The  law  requires  that  such  person  be  deported  on  the  same  ves- 
sel that  brought  him.  A  citizen  of  the  United  States  having  leprosy 
cannot  be  debarred.  Such  individuals  are  admitted  and  then  come  un- 
der the  health  laws  of  the  state  or  port  of  entry. 

Specific  Prevention. — There  is  no  specific  prevention  or  cure  for 
leprosy.  Surgical  cleanliness  and  frequent  dressings  help  check  the 
spread  of  the  infection.  Nastin  is  a  substance  proposed  by  Deycke  and 
consists  of  a  neutral  fat  obtained  from  a  streptothrix.  The  reports  from 
its  use  are  not  particularly  encouraging.  Eost,  of  Eangoon,  Burmah,  uses  a 
substance  which  he  calls  "leprolin,"  a  precipitate  from  leprous  tubercles. 
A  large  proportion  (75  to  80  per  cent.)  of  lepers  give  a  positive  Was- 
sermann  reaction  (independent  of  syphilis),  but  not  the  luetin  reaction. 
Tuberculin  in  somewhat  large  doses  injected  subcutaneously  into  leprous 
patients  produces  both  a  general  and  local  reaction,  but  the  repeated  in- 
jections do  not  materially  influence  the  disease,  although  such  treatment 
seems  to  cause  a  local  improvement  or  softening  of  the  leprous  tubercules. 
Heiser  in  Manila  reports  favorable  local  results  from  the  application  of 
X-rays.  Chaulmoogra  oil  and  Gurjun  balsam  have  been  extensively  used. 
Dyer  in  Louisiana  has  obtained  good  results  from  good  food,  fresh  air, 
cleanliness,  and  the  general  principles  applicable  to  the  modern  treatment 
and  prevention  of  tuberculosis. 

In  appraising  the  influence  of  treatment  it  must  be  borne  in  mind 
that  leprosy  is  prone  to  prolonged  periods  of  quiescence  and  that  marked 
improvement  often  occurs  spontaneously, 

REFERENCES 

Hansen:    Virchow's  Archiv,  1882,  Bd.  XC,  p.  542  [original  description  of 

the  bacillus]. 
Kedrowski,  W.  J.:  Centralbl.  f.  Bakt.,  etc.     1  Abt.  Kef.,  1911,  Xo.  50,  p. 

143  [Diphtheroid  bacillus]. 
Bertarelli,  E.  :  Centralbl.  f.  Bakt.,  etc.     1  Abt.  Eef.,  1911,  Bd.  49,  Xo.  3, 

p.  65  [good  review  and  long  list  of  references]. 
Marchoux  and  Sorel  (Eat  Leprosy)  :     Ann.  de  I'lnst.  Pasteur,  1912,  Vol. 

26,  Xos.  9  and  10. 
Lepra.    A  journal  containing  everything  upon  the  subject.    Published  since 

March,  1900. 


CHAPTER  VI 
MENTAL  HYGIENE! 

By  Thomas  W.  Salmon,  M.  D. 

Medical  Director,  National  Committee  for  Menial  Hygiene;  formerly 

Passed  Assistant  Surgeon,  U.  8.  Public  Health  Service;  formerly 

Chairman,  New  York  State  Board  of  Alienists. 

A  very  few  years  ago  it  would  have  been  difficult  to  justify  the  in- 
clusion of  a  chapter  on  mental  hygiene  in  a  general  treatise  on  preventive 
medicine  and  hygiene.  The  medico-legal  term  "insanity"  was  used  to 
designate  all  abnormal  mental  states  and  the  incorrect  conception  of 
mental  and  physical  diseases  as  distinct  and  practically  unrelated  was 
widely  accepted.  These  misconceptions  and  the  hopelessness,  both  as 
to  cure  and  prevention,  which  characterized  the  medical  attitude  toward 
mental  diseases  combined  to  disassociate  mental  medicine  and  its  prob- 
lems from  the  subjects  which  were  engaging  the  attention  of  physicians 
and  sanitarians  generally.  There  seemed  little  likelihood  that  the  de- 
termination to  prevent  diseases  which  was  beginning  to  dominate  the 
medical  profession  would  soon  extend  into  the  domain  of  mental  medi- 
cine. Today,  however,  a  treatise  on  the  prevention  of  disease  which  failed 
to  include  a  chapter  on  mental  hygiene  would  neglect  an  important  field 
of  preventive  medicine.  The  realization  that  many  forms  of  mental  dis- 
ease depend  in  a  large  measure  upon  preventable  causes,  the  rapid  growth 
of  psychiatry  and  its  acceptance  as  a  department  of  scientific  medicine, 
and  the  newly  discovered  opportunities  for  utilizing  its  resources  in  prac- 
tical attempts  to  deal  with  social  problems  have  broken  down  the  barriers 
which  so  long  and  so  effectually  isolated  mental  medicine. 

It  is  not  easy  to  present  even  the  main  facts  of  mental  hygiene 
within  the  limits  of  a  single  chapter,  for  it  is  not  sufficient  to  discuss 
some  of  the  more  important  preventable  or  modifiable  causes  of  mental 
diseases  and  mental  deficiency  and  to  outline  some  of  the  means  which 
may  be  employed  in  their  control.  Hygiene  deals  with  measures  which 
promote  health  as  well  as  with  the  prevention  of  disease  and  it  is  neces- 

^  In  the  first  edition  this  chapter  was  called  "Tlie  Prevention  of  Mental  Dis- 
eases," but  the  prevention  of  mental  diseases  is  only  a  relatively  small  part  of 
the  field  of  mental  hygiene.  Therefore,  in  this  edition  both  the  title  and  the 
scope  of  this  chapter  have  been  changed  to  "Mental  Hygiene." 

331 


332  MENTAL   HYGIENE 

sary,  in  any  useful  presentation  of  the  csseiitiais  of  mental  hygiene, 
to  consider  to  what  extent  some  of  the  mental  factors  which  interfere 
with  the  successful  adaptation  of  the  individual  to  the  environment  can 
he  favorahly  modified.  It  is  clearly  within  the  sphere  of  mental  hygiene 
to  strive  to  prevent  those  failures  of  adaptation  which,  while  they  may 
never  bring  about  the  graver  disturbances  of  adjustment  which  we  term 
mental  diseases  (psychoses),  may,  nevertheless,  distort  the  life  and  pro- 
foundly impair  the  efficiency  and  happiness  of  the  individual. 

IMPORTANCE  OF  THE  PROBLEMS  OF  MENTAL  HYGIENE  ^ 

On  the  date  of  the  last  federal  census,  January  1,  1910,  there  were 
187,454  persons  in  institutions  for  the  insane  in  this  country.  This 
number  exceeded  the  number  of  students  in  all  the  colleges  and  universi- 
ties in  the  United  States.  It  exceeded  the  number  of  officers  and  en- 
listed men  in  the  United  States  Army,  Navy,  and  Marine  Corps,  and  also 
the  population  of  Columbus,  Ohio,  our  twenty-ninth  city  in  size.  This 
great  number  by  no  means  includ'ed  all  persons  with  mental  diseases  in 
this  country  or  even  the  number  who  would  have  been  receiving  treatment 
in  institutions  at  that  time  had  all  the  States  supplied  adequate  pro- 
visions. We  know  that  the  ratio  of  persons  with  mental  diseases  to  the 
whole  population  is  about  the  same  in  different  parts  of  the  country,  for 
wherever  sufficient  institutional  provisions  exist  they  are  utilized  to  very 
much  the  same  extent.  If,  therefore,  all  the  States  provided  for  the 
insane  as  adequately  as  do  Massachusetts  and  New  York  there  would 
have  been  more  than  300,000  patients  in  institutions  on  January  1,  1910, 
instead  of  187,454.  The  cost  of  caring  for  mental  diseases  in  a  State 
which  makes  adequate  provisions  exceeds  any  single  item  of  expense  ex- 
cept that  for  public  education.  The  average  annual  cost  of  caring  for  a 
patient  in  a  State  hospital  for  the  insane  is  about  $175,  making  the  total 
cost  of  caring  for  the  patients  under  treatment  in  all  the  institutions  in 
the  country  in  1910  more  than  $30,000,000.  To  this  great  sum  should 
be  added,  if  we  are  to  state  fairly  the  cost  of  mental  diseases,  the  eco- 
nomic loss  through  the  withdrawal  from  active  life  of  more  than  30,000 
people  who  enter  these  institutions  each  year. 

No  one  can  state  the  number  of  the  mentally  defective  in  this  country 
or  even  the  number  requiring  institutional  care.  Massachusetts,  the  State 
which  has  supplied  institutional  provisions  most  liberally,  has  one  bed  to 
every  1,354  of  the  general  population  for  such  sufferers.^  If  this  ratio 
existed  in  every  State  there  would  be  74,747  persons  in  such  institutions 
at  the  present  time.     Actually  there  are  approximately  22,000.^     We 

^  From  reports  issued  by  the  National  Committee  for  Mental  Hygiene. 
^Not  including   epileptics,   unless   also   feeble-minded. 
'^  March  1,  1916. 


MENTAL    HYGIENE  333 

know,  however,  that  even  in  the  State  which  has  made  the  most  liberal 
provisions  there  are  many  mentally  defective  persons  uncared  for  and 
many  who  are  improperly  confined  in  correctional  institutions  or  in 
almshouses.  There  is  reason  to  believe  that  there  are  not  less  than  three 
mentally  defective  persons  in  every  thousand  of  the  whole  population. 
Although  their  cost  to  the  communities  through  their  own  dependence, 
the  support  of  their  illegitimate  children,  and  the  crimes  and  misde- 
meanors which  they  commit,  or  more  frequently  invite,  cannot  be  esti- 
mated, we  know  that  it  is  more  even  than  the  great  cost  of  caring  for 
them  in  suitable  institutions  would  be. 

Such  statistics  as  these  serve  as  a  convenient  means  for  comparing 
the  cost  of  mental  diseases  and  mental  deficiency  with  that  of  other 
diseases,  but  they  cannot  convey  an  adequate  idea  of  the  personal  suffer- 
ing and  unhappiness  and  the  social  and  family  disasters  for  which  mental 
disorders  are  directly  responsible.  It  should  be  remembered  that  the 
same  causes  which  bring  about  the  commitment  of  many  thousands  of 
persons  as  "insane"  each  year  are  responsible  for  much  mental  disease 
which  is  never  recognized  and  for  many  failures  in  adaptation  which 
prevent  people  from  meeting  difficult  situations  in  life  and  which  lead 
to  innumerable  conflicts  with  laws  and  conventions.  To  avert  some  of 
these  disasters  is  as  much  the  task  of  mental  hygiene  as  to  control  the 
preventable  causes  of  mental  disease  and  of  mental  deficiency.  With 
these  considerations  in  mind,  some  of  the  causes  of  mental  diseases,  men- 
tal deficiency,  and  other  abnormal  mental  states  will  be  briefly  stated. 
Measures  of  prevention  which  seem  applicable  will  be  considered  while 
discussing  each  cause,  and  the  more  general  causative  conditions  and 
more  general  measures  for  preventing  mental  disease  and  promoting 
mental  hygiene  will  be  taken  up  last. 

Definitions. — In  the  pages  which  follow,  the  term  psychoses  refers  to 
mental  diseases,  or  "forms  of  insanity"  as  they  are  more  familiarly  but 
less  accurately  called.  Dr.  William  A.  White  has  pointed  out  the  enor- 
mous advantages  of  restricting  the  use  of  the  term  "insane"  to  that 
group  of  persons  who  suffer  from  civic  disabilities  of  one  kind  or  another 
(commitment  to  institutions,  testamentary  incapacity,  incompetency  to 
use  property,  etc.)  because  of  legal  proceedings  necessitated  by  mental 
diseases.  Insanity  thus  becomes  a  strictly  legal  term,  with  which 
physicians  and  sanitarians  are  concerned  only  when  medico-legal  or 
certain  social  phases  of  mental  diseases  are  under  consideration.  Per- 
sons with  mental  disease  may  or  may  not  be  "insane."  The  term  insanity 
will  be  used  here  only  in  this  medico-legal  sense.  The  term  mental 
deficiency  will  be  used  to  designate  the  various  types  and  degrees  of 
mental  defect  (idiocy,  imbecility,  feeble-mindedness,  psychopathic  in- 
feriority, etc.)  existing  at  birth  or  arising  during  the  early  period  of 
development.     It  is  not  possible  to  find  a  single  word  with  which  to 


334  MENTAL    HYGIENE 

designate  those  minor  interferences  with  mental  liealth  or  with  mental 
efficiency  which  underlie  many  such  difficulties  of  adaptation  as  those 
which  have  been  mentioned. 

HEREDITY 

Psychoses. — The  accepted  theories  of  heredity  and  the  general  re- 
lation of  heredity  to  disease  have  been  considered  elsewhere  (Chapters  1 
and  II,  Section  II,  pages  389,  470).  In  examining  the  relation  of  hered- 
ity to  mental  diseases,  the  advantage  of  dropping  the  use  of  the  medico- 
legal term  "insanity''  is  apparent  for  statistical  studies  indicate  that 
in  some  mental  diseases  heredity  is  a  factor  of  the  utmost  importance, 
while  in  others  it  apparently  influences  causation  very  little  if  at  all. 

Eosanoff  and  Orr  ^  concluded  from  a  study  of  inheritance  in  73  cases 
of  mental  diseases,  representing  206  different  matings  and  1,097  off- 
spring, that  this  common  basis,  which  they  designated  the  "neuropathic 
constitution,"  is  inherited  in  accordance  with  Mendel's  law.  They  be- 
lieved the  neuropathic  constitution  to  be  a  trait  which  is  recessive  to 
the  normal  and,  furthermore,  that  various  clinical  neuropathic  manifesta- 
tions bear  to  each  other  the  relationship  of  traits  of  various  degrees  of 
recessiveness ;  that  is  to  say,  neuropathic  traits  which  are  recessive  com- 
pared with  normal  traits  are  at  the  same  time  dominant  over  other  neuro- 
pathic traits.  The  degree  to  which  neuropathic  traits  are  recessive  seemed 
to  Eosanoff  and  Orr  to  conform  in  general  to  the  severity  of  the  type 
of  psychosis  or  neurosis.  Unfortunately,  these  findings  alone  are  not 
sufficient  evidence  upon  which  to  base  general  conclusions  as  to  the  rela- 
tion between  heredity  and  mental  diseases.  The  study  of  the  inheritance 
of  mental  diseases  presents  many  complex  problems  and  many  special  dif- 
ficulties, not  the  least  of  which  is  that  the  field  work  upon  which  it  de- 
pends so  greatly  cannot  be  entrusted  to  workers  who  have  not  had  psychi- 
atrical training.  Dr.  E.  Eiidin  of  Munich  has  made  very  careful  studies 
of  inheritance  in  mental  diseases,  his  investigations  being  particularly 
valuable  because  he  performed  the  actual  field  work  himself.  In  a 
communication  summing  up  his'  findings  from  1909  to  1911,  he  stated  ^ 
that  he  felt  that  he  had  not  done  enough  work  to  justify  the  formulation 
of  laws  regarding  the  hereditary  factors  of  mental  diseases.  Scientific 
study  of  this  subject  is  being  carried  on  actively  and  it  seems  desirable, 
at  the  present  time,  to  reserve  judgment  as  to  the  conflicting  findings 
which  are  being  presented.^ 

^  Rosanoff,  A.  J.,  and  Orr,  Florence  I. :  "The  Study  of  Heredity  in  Insanity 
in  the  Light  of  the  Mendelian  Theory;"  Bulletin  No.  V,  Eugenics  Record  Office. 

^Riidin,  E. :  Zeitschrift  fur  die  Gesammte  Neurologic  und  Psychiatric,  Vol. 
7,  Part  5,  November  18,  1911. 

^  The  reader  who  is  interested  in  this  phase  of  mental  hygiene  will  find  an 
excellent  bibliography,  after  Riidin,  in  "Some  Problems  in  the  Study  of  Heredity 
in  Mental  Disease"  by  Dr.  H.  A.  Cotton;  American  Journal  of  Insanity,  July, 
1912. 


MEl^TTAL    HYGIENE  335 

If  the  precise  part  played  by  inheritance  in  the  causation  of  mental 
diseases  cannot  be  stated,  it  should  not  be  thought  that  evidence  is 
lacking  to  show  its  importance.  It  is  probably  safe  to  say  that  heredity 
is  responsible,  directly  and  indirectly,  for  more  cases  of  mental  disease 
than  any  other  single  cause.  In  about  50  per  cent,  of  all  admissions  tt 
hospitals  in  which  careful  records  are  made  and  scientific  study  of 
cases  is  carried  on,  the  history  of  mental  diseases  in  other  members 
of  the  family  is  found.  There  are  no  statistics  in  this  country  to  show 
the  percentage  of  normal  persons  in  whose  families  the  history  of 
mental  disease  is  found,  but  studies  elsewhere  have  shown  it  to  be  from 
3  to  7.5  per  cent. 

Neuropathic  heredity  exercises  powerful  indirect  influences  through 
the  unfavorable  environmental  influences  in  which  the  children  of 
psychotic  parents  are  compelled  to  spend  their  developmental  years. 
Distorted  views  of  life,  queer  religious  and  political  beliefs  and  various 
antisocial  attitudes  on  the  part  of  such  parents  mould  the  mental  reac- 
tions of  their  children  and  even  when  no  direct  hereditary  tendency  is 
transmitted  such  children  suffer  through  having  their  education  inter- 
fered with  and  their  capacity  for  social  adjustment  restricted.  In  some 
cases  they  acquire  and  firmly  hold  false  beliefs  which,  on  the  part  of  their 
parents,  were  actually  delusional. 

Mental  Deficiency. — In  mental  deficiency  we  have  one  of  the  best 
examples  of  a  pathological  condition  directly  transmitted  by  inheritance. 
Although  the  same  type  of  neuropathic  heredity  which  is  met  so  often 
in  the  psychoses  is  found  more  frequently  in  the  mentally  defective 
than  in  normal  persons,  mental  deficiency  depends  chiefly  upon  a  more 
specific  kind  of  inheritance — the  direct  transmission  of  the  same  condi- 
tion. Goddard  ^  found,  in  300  family  histories  in  which  the  data  were 
regarded  as  satisfactory,  that  54  per  cent,  showed  mentally  defective 
relatives  "in  such  numbers  or  in  such  relations  to  the  individual  case 
studied  as  to  leave  no  doubt  of  the  hereditary  character  of  mental  defect." 
He  considered  11.3  per  cent,  of  the  remaining  cases  in  this  series  as 
"probably  hereditary."  Other  studies  have,  unfortunately,  grouped 
mental  deficiency,  mental  diseases  and  epilepsy  in  estimating  the  heredi- 
tary factors  in  mental  deficiency.  Tredgold  '  found,  in  a  series  of  200 
cases  in  which  he  very  carefully  investigated  the  family  histories,  that 
64.5  per  cent,  had  mental  deficiency,  mental  diseases,  or  epilepsy  in  their 
ancestry.  Lapage  ^  found  the  same  conditions  in  the  families  of  48.4 
per  cent,  of  the  children  in  the  special  schools  of  Manchester,  and 
Potts  *  found  45.6  per  cent,  in  the  families  of  children  in  similar  schools 
in  Birmingham. 

1  Goddard,  H.  H.:      "Feeblemindedness,"   1915,  p.  436. 

==  Tredgold,  A.  F.:      "Mental  Deficiency,"   1914,  p.  40. 

^Lapage,   C.  P.:      "Feeblemindedness  in  Children,"    1911. 

*  Potts,  W.  A.;     British  Journal  of  Children's  Diseases,  March.  1909. 


336  MENTAL    HYGIENE 

In  Tredgold's  series  of  200  cases,  a  marked  predisixtsilion  lo  paral- 
ysis, cerebral  hemorrhage  and  various  neuroses  exisied  in  18  per  cent., 
making  the  proportion  in  which  either  a  mental'y  defective  or  neuro- 
pathic heredity  was  found  82.5  per  cent.  (Joddard  found  epilepsy, 
insanity,  blindness,  and  deafness  (which  he  grouped  under  the  term 
"neuropathic  ancestry")  in  12  per  cent,  of  his  series.  It  is  most  un- 
fortunate that  different  methods  of  grouping  neuropathic  conditions 
should  be  employed  by  different  investigators,  for  it  makes  it  impossible 
to  compare  their  results.  It  is  also  unfortunate  that  widely  different 
conditions  should  be  included  in  the  same  group.  Certainly  blindness 
and  insanity  must  represent  very  different  types  of  heredity  in  God- 
dard's  cases,  while  cerebral  hemorrhage  and  the  neuroses  are  equally 
incongruous  members  of  the  same  group  in  Tredgold's  series. 

There  is  need  for  miich  more  intensive  study  of  heredity  in  mental 
deficiency,  especially  in  those  cases  in  which  neuropathic  inheritance 
and  not  mental  deficiency  is  found  in  the  progenitors.  Even  in  the 
large  proportion  of  cases  in  which  mental  deficiency  seems  to  be  trans- 
mitted directly,  it  is  desirable  to  know  the  relation  of  heredity  to  the 
different  types  and  grades  of  mental  deficiency.  As  a  step  in  this  direc- 
tion, Goddard  has  pointed  out  that  his  series  seemed  to  indicate  that 
low^-grade  cases  come  from  families  with  the  least  amount  of  mental 
defect.  In  the  interpretation  of  this  interesting  fact,  the  barriers  to 
reproduction  which  exist  among  low-grade  defectives,  their  high  mor- 
tality rate  before  puberty  and  the  excessive  prevalence  among  them 
of  severe  organic  lesions  of  the  brain,  many  of  them  accidental  or 
syphilitic,  must  be  taken  into  account.- 

The  relation  of  heredity  to  mental  deficiency  is  a  matter  of  the 
greatest  importance  on  account  of  its  bearing  upon  prevention.  The 
general  fact  that  mental  deficiency  depends  chiefly  upon  inheritance 
having  been  well  established,  it  seems  most  essential  now  to  study 
heredity  specifically,  as  we  do  in  the  psychoses — that  is,  wdth  reference 
to  particular  types  and  grades.  If  the  Judicial  authorities  are  to  be 
asked  to  commit  a  mentally  defective  person  to  an  institution  for  life 
solely  because  of  the  danger  of  transmitting  his  defect  to  others,  they 
have  a  right  to  ask  what  is  known  beyond  reasonable  doubt  regarding 
the  hereditary  factors  in  that  particular  case  and  in  that  particular  type 
of  mental  deficiency.  It  is  quite  certain  that  they  will  look  with  sus- 
picion upon  long-distance  diagnoses  by  inexpert  investigators  and  yet  it  is 
upon  precisely  that  kind  of  diagnosis  which  much  of  the  information 
which  we  are  making  widely  known  today  depends.  In  determining  the 
heredity  of  a  given  case  much  depends  upon  establishing  the  existence 
of  mental  defect  in  many  living  persons  not  in  institutions  and  in  others 
long  since  dead.  Many  field  workers  engaged  in  such  studies  are  poorly 
equipped  by  training  to  diagnose  mental   deficiency  even  in  a  formal 


MENTAL   HYGIENE  337 

examination,  with  all  the  aids  available  for  such  work,  and  some  of  them 
are  qnite  inexperienced  in  estimating  the  significance  of  various  types 
(jf  antisocial  conduct.  It  has  been  said  in  justification  of  some  rather 
questionable  findings  of  such  workers  that  physicians  conclude  upon 
evidence  "infinitely  weaker"  that  Napoleon,  Julius  Caesar,  and  Saint 
Paul  were  epileptics.  Without  considering  the  striking  outward  manifes- 
tations of  epilepsy,  it  should  be  said  that  extensive  medical  notes  by 
Napoleon's  physicians  are  in  existence  and  that  the  data  regarding 
Julius  Csesar  upon  which  the  existence  of  epilepsy  is  assumed  are  not 
much  less  trustworthy  than  those  available  regarding  some  obscure 
feeble-minded  persons  who  died  fifty  or  more  years  ago.  It  is  to  be  re- 
membered, however,  that  the  diagnoses  of  the  maladies  of  great  his- 
torial  characters  which  are  offered  from  time  to  time  by  physicians  are 
presented  merely  as  interesting  surmises,  not  as  scientific  data  upon 
which  to  base  an  extensive  program  of  legislation  and  institutional 
provision. 

It  is  of  much  practical  importance,  Math  reference  to  prevention,  to 
know  if  hereditary  mental  deficiency  is  transmitted  in  accordance  with 
definite  laws.  Goddard's  investigations  showed  a  correlation  between  the 
actual  findings  and  the  proportion  of  mental  defectives  which,  theoret- 
ically, should  occur  in  the  324  matings  of  different  types  in  his  series  if 
mental  deficiency  is  transmitted  in  accordance  with  Mendel's  law  to 
justify  him  in  saying  that  "such  results  are  difficult  to  account  for  on 
any  other  basis  than  that  feeble-mindedness  is  transmitted  in  accord- 
ance with  the  Mendelian  formula." 

Preventive  Measures. — This  is  the  domain  of  eugenics,  a  subject 
which  is  considered  elsewhere  in  this  volume  (Section  II,  Chapter  II). 
In  considering  measures  for  controlling  the  inheritance  of  the  neuro- 
pathic constitution  the  caution  contained  in  the  following  statement 
by  Adolf  Meyer  ^  may  well  be  borne  in  mind :  "In  such  a  matter  as  the 
prevention  of  mental  trouble  due  to  heredity,  I  maintain  that,  although 
we  know  that  a  large  percentage  of  mental  cases  have  a  history  of 
heredity,  there  is  not  a  sufficiently  decisive  body  of  facts  established  for 
us  to  be  justified  in  making  sweeping  rules  against  the  marriage  of 
those  who  have  had  mental  troubles  either  themselves  or  in  their  families. 
Indeed,  we  might  thereby  run  the  risk  of  doing  a  grave  injustice  to  the 
race  as  well  as  infringing  on  the  rights  of  the  individual." 

In  the  case  of  hereditary  mental  defect  there  can  be  no  question 
that  the  right  of  the  individual  to  bear  children  must  be  disregarded 
in  the  interests  of  ordinary  humanity  as  well  as  in  the  interests  of  the 
race.  The  questions  of  the  sterilization  and  segregation  of  the  defective 
and  the  regulation  of  marriage  are  considered  elsewhere,  but  it  should 

^ Meyer,  Adolf:  "Organizing  the  Community  for  the  Protection  of  Its  Men- 
tal Health,"  The  Purvey,  September  18,   1915. 


338  MENTAL    HYGIENE 

be  said  here  that  in  not  a  few  mentally  defective  persons  there  is  an 
alternative  to  segregation  in  an  institution  for  life.  It  is  possible 
to  devise  a  system  of  safeguards  which,  with  registration  and  commit- 
ment to  guardianship  if  necessary,  will  make  a  supervised  life  in  the 
community  safe  for  a  very  carefully  selected  number  of  such  indi- 
viduals. The  establishment  of  such  a  system  of  supervision  and  registra- 
tion is  one  of  the  great  constructive  tasks  which  must  be  undertaken  if 
we  are  to  deal  with  the  problem  of  the  mentally  defective  in  the  most 
humane  and  effective  manner  possible. 

ALCOHOL 

Psychoses. — In  discussing  alcohol  as  a  cause  of  mental  disease  it 
is  very  desirable  to  indicate  whether  it  is  being  considered  as  a  direct 
cause  or  as  one  of  several  etiological  factors.  Alcohol  is  the  essential 
cause  of  the  alcoholic  psychoses,  those  mental  diseases  which  from 
their  symptoms,  pathology,  or  course  we  have  come  to  recognize  as 
due  directly  to  alcohol.  In  these  disorders — Korsakow's  disease,  alcoholic 
hallucinosis,  delirium  tremens,  alcoholic  deterioration — to  diagnose  the 
condition  is  to  know  the  cause.  Other  causes,  such  as  trauma  and  dis- 
orders of  nutrition,  doubtless  contribute  in  many  cases  and  in  a  very 
large  proportion  of  cases  the  neuropathic  constitution  underlies  the  habit 
of  alcoholism,  but  whatever  other  mental  diseases  these  patients  might 
sometime  have,  they  could  not  develop  these  particular  psychoses  with- 
out the  intemperate  use  of  alcohol.  The  alcoholic  psychoses  account 
for  about  12  per  cent,  of  all  first  admissions  to  hospitals  for  the  insane. 
They  occur  about  three  times  as  frequently  in  men  as  in  women  and, 
in  general,  more  frequently  in  admissions  from  cities  than  from  rural 
districts.  This  difference  in  the  environment  of  admissions  for  alcoholic 
psychoses  is  much  more  striking  in  the  case  of  women  than  in  men.^ 

It  is  difficult  and  perhaps  impossible  to  estimate  the  influence  of 
alcohol  in  the  causation  of  other  psychoses.  Of  the  cases  in  which  a 
satisfactory  history  as  to  alcoholic  habits  was  obtained  in  the  patients 
admitted  to  the  New  York  State  hospitals  during  1914,  about  23  per  cent, 
were  intemperate.  Excluding  the  alcoholic  psychoses,  the  prevalence 
of  intemperance  among  the  more  important  psychoses  is  shown  by  the 
table  on  the  next  page. 

No  statistics  are  available  to  show  the  extent  of  intemperance  among 
adults  in  the  community  generally,  nevertheless  it  seems  very  likely  that 
it  is  much  less  than  in  even  the  psychoses  showing  the  least  frequency. 
Many  elements  have  to  be  taken  in  consideration  in  interpreting  these 

^  There  has  been  a  steady  fall  in  the  percentage  of  admissions  with  alcoholic 
psychoses  during  recent  years.  This  may  be  partly  accounted  for  by  better  dis- 
tribution of  cases  formerly  thought  to  be  alcoholic  psychoses  but  it  is  possibl;' 
that  it  is  due  in  part  to  the  growing  temperance  movement, 


MENTAL    HYGIENE  339 

Per  cent. 
Psychoses  Intemperate 

Senile  psychoses 13.9 

General  paresis 29.0 

Psychoses  with  organic  brain  disease 19.3 

Dementia  precox   10.4 

Paranoic  conditions 10.4 

Epileptic  psychoses   17.9 

Manic-depressive  psychosis 10.7 

percentages,  especially  the  fact  that  defects  in  judgment  and  relaxation 
of  inhibitions  due  to  mental  disease  lead  to  intemperance,  as  they  do  to 
other  disorders  of  conduct.  It  is  significant,  therefore,  that  general 
paresis  .shows  the  highest  percentage  of  intemperance.  The  seclusive- 
ness  of  persons  with  paranoic  tendencies  and  dementia  precox  and  the 
low  percentage  of  alcoholism  in  these  disorders  may  bear  some  rela- 
tion to  the  influence  of  conviviality  upon  intemperance. 

In  many  individual  cases  there  is  abundant  evidence  that  intemper- 
ance plays  a  prominent  part  in  the  psychoses  which  are  not  primarily 
dependent  upon  alcohol.  The  effects  of  alcohol  in  producing  excited 
episodes  in  the  mentally  defective  is  well  known  and  intemperance 
lends  a  tremendous  impetus  to  the  retrogressive  changes  in  senility.  As 
a  result  of  greatly  increased  attention  being  directed  to  the  alcoholic 
psychoses,  interesting  facts  are  being  brought  out.  It  has  recently  been 
shown  by  Pollock  ^  in  a  study  of  464  cases  of  the  alcoholic  psychoses 
that  the  average  duration  of  intemperance  before  the  onset  of  the  psycho- 
sis was  20.6  years.  As  will  be  seen,  this  fact  has  an  important  bearing 
upon  prevention.  It  does  not  seem  amiss  to  point  out  here  the  mis- 
leading impression  which  is  given  by  the  statement  often  made  that 
alcohol  is  "filling  our  hospitals  for  the  insane."  The  alcoholic  psychoses 
are  of  comparatively  short  duration  and  the  number  of  patients  with 
these  diseases  under  treatment  at  any  time  is  always  less  than  the  annual 
admission  rate  of  these  diseases.  Such  statements  made  by  enthusiastic 
temperance  advocates  injure  a  splendid  cause  for  the  exaggerated  esti- 
mates given  make  it  impossible  to  show  the  expected  reduction  in  the 
number  of  patients  in  the  hospitals  of  prohibition  States  after  prohibi- 
tion has  gone  into  effect,  thus  providing  the  enemies  of  prohibition  with 
arguments  in  advocacy  of  license. 

Mental  Deficiency. — Statistics  regarding  alcohol  as  a  cause  of  men- 
tal deficiency  deal  wholly  with  the  influence  which  intemperance  in  the 
parents  is  said  to  exercise.  The  data  available,  while  abundant,  are  very 
unsatisfactory  and  have  to  be  interpreted  with  especial  care  on  account 

^Pollock,  Horatio  M. :  "The  Use  and  Effect  of  Alcohol  in  Relation  to  the 
Alcoholic  Psychoses,"  New  York  State  Hospitals  Bulletin,  August,  1915. 


340  MENTAL   HYGIENE 

of  the  fact  that  the  alcoholic  parents  whose  habits  are  so  often  thought 
to  have  been,  responsible  for  mental  deficiency  in  their  children  were 
also  mentally  defective  and  in  reality  transmitted  their  defect  directly. 
Tredgold  states  that  a  family  history  of  alcoholism  was  present  in  46.5 
per  cent,  of  the  series  of  200  cases  which  he  studied  carefully,  but  that 
no  less  than  five-sixths  of  these  cases  with  an  alcoholic  parentage  also 
had  a  well-defined  neuropathic  inheritance.  He  believes  that  paternal 
or  maternal  alcoholism  may  produce  mental  deficiency  in  the  offspring 
without  other  cause,  but  that  this  is  rare.  In  a  very  interesting  chapter. 
Groddard  discusses  the  alcoholics  (drunkards)  among  the  parents  in  his 
series  of  cases  and  concludes  that  "everything  seems  to  indicate  that  alco- 
holism itself  is  only  a  symptom,  that  it  for  the  most  part  occurs  in 
families  where  there  is  some  form  of  neurotic  taint,  especially  feeble- 
mindedness." He  points  out  that  if  alcoholism  were  responsible  alone 
for  mental  deficiency  there  would  doubtless  be  much  more  mental 
deficiency  than  there  is,  especially  in  view  of  the  great  prevalence  of 
drunkenness  among  all  classes  only  a  few  generations  ago. 

Intemperance  at  the  time  of  conception  is  popularly  thought  in  many 
countries  to  be  a  cause  of  mental  deficiency.  Analyzing  the  last  Swiss 
census,  Bezzola  pointed  out  that  there  are  two  maximal  periods  in  which 
the  mentally  defective  persons  enumerated  were  conceived — the  time  of 
the  vintage  and  the  time  of  the  Lenten  carnival,  occasions  of  great 
revelry.  In  the  wine  cantons  the  time  of  the  vintage  was  the  time  of 
conception  in  a  great  majority  of  idiots.  Ireland  ^  examined  the  birth 
dates  of  mentally  defective  children  born  in  certain  villages  in  Scotland 
where  there  is  much  seasonal  drunkenness  to  see  if  their  conception 
dates  bore  a  relation  to  such  periods,  but  was  vmable  to  find  any  such 
evidence  as  that  discovered  by  Bezzola.  P.  Nacke  ^  gives  it  as  his 
opinion  that,  while  intoxication  at  the  time  of  conception  may  result  in 
mental  deficiency  in  the  offspring,  such  an  event  is  extremely  rare. 
This  seems  in  accordance  with  the  biological  facts  of  conception.  The 
extent  of  the  popular  belief  that  some  delinquency  on  the  part  of  the 
parents  is  responsible  for  mental  deficiency  in  their  children  was  im- 
pressed upon  me  while  questioning  the  parents  of  mentally  defective 
immigrants  at  Ellis  Island.  I  had  an  opportunity  to  ask  hundreds  of 
such  parents,  representing  nearly  all  the  European  races,  what  they 
considered  to  be  the  real  cause  of  the  mental  deficiency  of  their  children 
and,  while  many  of  them  gave  all  kinds  of  infantile  accidents  and  very 
few  of  them,  as  might  be  expected,  suggested  hereditary  influence,  a 
considerable  number  said  shamefacedly  that  they  thought  it  was  due  to 
intoxication  at  the  time  of  conception,  to  early  sexual  faults  or  to  failure 
to  obey  the  Hebrew  injunctions  regarding  intercourse  after  marriage. 

^Ireland,  W.  W.:     "Mental  Affections  in  Childhood,"  1898. 

"Nacke,  P.:     "Die  Zengiuio   [m  Rausche,"  Neurol.  Centralbl..  No.  2,  1908. 


MEIn^TAL    hygiene  341 

Experiments  such  as  those  of  Kraepelin  ^  in  memory  tests,  type- 
writing and  typesetting  indicate  tliat  even  very  moderate  drinking  no- 
ticeably impairs  mental  efficiency.  These  are  effects  of  alcohol  which 
cannot  be  ignored  in  mental  hygiene. 

Preventive  Measures. — The  prevention  of  the  alcoholic  psychoses 
and  of  those  mental  diseases  in  which  alcohol  is  a  contributory  etiological 
factor  consists  in  the  control  of  alcoholism  and  the  promotion  of 
temperance.  These  matters  are  not  within  the  scope  of  a  chapter  on 
mental  hygiene.  Like  the  prevention  of  syphilis,  the  control  of  alcoholism 
is  a  great  social  question.  The  medical  man  can  help  best  by  contrib- 
uting information  as  to  the  ravages  of  these  two  enemies  of  the  race  and 
by  using  his  personal  and  professional  influence  to  aid  all  rational  move- 
ments for  reform.  If  alcohol  is  not  to  be  denied  to  all,  it  would  seem 
desirable  to  create  some  special  safeguards  for  the  neuropathic  component 
of  the  population  for  whom  it  involves  the  gravest  dangers.  It  is  the 
duty  of  the  physician  to  urge  total  abstinence  for  life  upon  such  people. 

At  the  Boston  Psychopathic  Hospital,  Dr.  E.  E.  Southard  has  formed 
a  club,  membership  in  which  is  restricted  to  those  who  have  recovered 
from  delirium  tremens  or  an  alcoholic  psychosis  in  that  institution. 
Such  associations — for  mutual  help  and  encouragement — of  those  to 
whom  successful  abstinence  is  the  only  means  of  preserving  mental 
health  or  even  life  itself  have  been  found  elsewhere  to  be  valuable 
aids. 

The  findings  of  Pollock  that  the  psychoses  come,  as  a  rule,  late  in 
the  course  of  chronic  intemperance  and  often  after  repeated  attacks 
of  delirium  tremens  should  give  renewed  impetus  to  all  movements  to 
reclaim  the  intemperate.  The  establishment  of  State  and  municipal 
colonies  for  the  treatment  of  alcoholism  will  yield  a  rich  return  in  the 
prevention  of  the  alcoholic  psychoses.  Anyone  interested  in  this  move- 
ment should  study  the  plans  of  the  New  York  City  Board  of  Inebriety 
and  the  management  of  the  Farm  Colony  which  that  Board  has  estab- 
lished. Such  movements  as  the  "Big  Brothers"  are  efficient  forces  in  this 
work  and  much  can  be  said  in  favor  of  their  aid  by  public  funds,  in  view 
of  the  valuable  public  service  which  they  perform. 

While  groups  of  people,  including  those  especially  predisposed  to 
alcoholism,  can  be  protected  to  a  certain  extent  by  various  movements 
for  regulation  of  the  liquor  traffic,  individual  prophylaxis  must  depend 
chiefly  if  not  wholly  upon  voluntary  abstinence.  Recent  progress  in  the 
study  of  mental  mechanisms  has  provided  new  knowledge  of  great  value 
in  understanding  the  sources  from  which  the  alcoholic  craving  really 
springs  and,  in  not  a  few  cases,  in  devising  plans  for  prevention  or 
successful  treatment.     Careful  personal  study  of  many  inebriates  show 

^Reported  by  Smith,  A.:  Archiv  fur  Psychiatrie,  1895.  Aschaffenberg,  G,; 
Psychologische  Arbeiten,  1896. 


342  MENTAL    HYGIENE 

quite  clearly  that  inebriety  usually  represents  a  llij^lit  fn^iii  rciality  very 
similar  to  that  seen  in  the  psychoses  and  neuroses  (page  333).  Deter- 
mining by  psycho-analysis  and  other  methods  of  psychiatrical  investiga- 
tion the  nature  of  the  dithcult  situation  from  which  the  individual  seeks 
to  fly  frequently  discloses  means  of  prevention  as  vi^ell  as  of  cure.  When 
it  is  impossible  to  modify  the  main  factors  which  have  given  rise  to 
conflicts  in  mental  life,  much  may  be  done  by  securing  a  more  construc- 
tive solution  of  the  problem  than  that  afforded  by  recourse  to  alcohol. 
Music,  art,  and  literature  present  avenues  of  escape  from  difficult  or 
intolerable  situations  in  real  life.  Wounded  self-esteem  can  be  restored 
by  the  satisfaction  which  comes  from  labor  for  the  welfare  of  others 
and  the  craving  for  alcohol  as  a  means  of  forgetting  or  transforming 
actuality  can  often  be  directed  in  safe  and  even  highly  constructive 
activities.  Such  forms  of  compensation  simply  suggest  that  useful 
work  in  the  prevention  or  control  of  inebriety  can  be  accomplished  by 
attempting  to  rehabilitate  the  individual  by  using  psychological  re- 
sources. It  must  be  insisted  upon,  however,  that  this  is  an  undertaking 
which  cannot  be  carried  on  with  groups.  It  is  applicable  to  individuals 
and  then  only  after  careful  personal  analysis  in  each  case.  Our  hope 
of  controlling  or  treating  inebriety  more  successfully  depends,  therefore, 
upon  concentration  upon  the  individual  inebriate. 

OTHER   EXOGENOUS   POISONS 

Morphinism  and  other  drug  addictions  are  responsible  for  less  than 
one  per  cent,  of  first  admissions  to  hospitals  for  the  insane  in  this  country. 
Fewer  such  patients  are  admitted  in  New  York  and  Massachusetts  now 
than  were  several  years  ago.  This  gratifying  fact  is  due,  in  part  at 
least,  to  stricter  enforcement  of  the  laws  regulating  the  sale  of  narcotics 
and  particularly  to  the  pure  food  laws  which  have  rendered  it  a  little 
more  difficult  to  dispense  habit-forming  drugs  in  patent  medicines. 
It  is  well  within  our  power  to  eliminate  this  cause  of  mental  disease  by 
wise  legislation  and  its  rigid  enforcement. 

A  very  small  proportion  of  admissions  is  caused  by  occupational 
poisonings.  This  small  proportion  can  be  still  further  reduced  by  increas- 
ing attention  to  measures  safeguarding  workmen  in  dangerous  trades. 

ENDOGENOUS   POISONS 

The  endogenous  poisons  which  are  formed  in  the  course  of  various 
organic  diseases  are  responsible  for  not  a  few  cases  of  mental  disease. 
Their  prevention  is  the  work  of  general  hygiene. 

The  relation  of  mental  diseases  to  disturbances  of  the  organs  with 
internal  secretions  is  a  field  for  study  which  as  yet  is  almost  unexplored. 


MENTAL   HYGIENE  343 

but  which  may  yield  many  opportunities  for  applying  preventive  meas- 
ures. 

Pellagra  is  responsible  for  thousands  of  cases  of  mental  disease  in  the 
localities  in  which  it  is  prevalent.  The  high  hopes  for  the  control  of 
this  disease  which  have  been  raised  by  the  discoveries  of  Goldberger  ^ 
make  it  practically  certain  that  pellagra  may  now  be  properly  counted 
a  preventable  cause  of  mental  disease.  The  studies  of  Lorenz  ^  in  which  it 
was  shown  that  the  pellagrous  psychoses  are  undoubtedly  toxic  is  an 
instance  of  the  aid  which  psychiatry  can  often  lend  other  branches  of 
medicine  in  the  new  and  useful  alliance  between  the  psychiatrist  and 
the  sanitarian.  The  non-infectious  origin  of  pellagra  was  strongly  indi- 
cated by  Lorenz's  findings  and  thus  assistance  was  given  toward  clearing 
the  way  for  the  discoveries  of  Goldberger. 

SYPHILIS 

Psychoses. — Among  the  infections,  syphilis  deserves  separate  con- 
sideration as  a  cause  of  mental  diseases  because  it  is  the  essential  cause 
of  general  paresis,  a  psychosis  responsible  for  about  13  per  cent,  of  all 
first  admissions  to  hospitals  for  the  insane.  More  than  one-fifth  of 
all  male  first  admissions  are  for  this  disease  and  in  one  very  large  hos- 
pital, which  receives  its  "patients  exclusively  from  New  York  City,  one 
in  four  of  the  male  patients  admitted  have  general  paresis.  The  prev- 
alence of  this  disease  is  about  three  times  as  great  among  men  as  among 
women.  Although  general  paresis  is  uniformly  fatal,  the  number  of 
deaths  reported  from  this  cause  does  not  give  an  adequate  idea  of  its 
frequency,  for  death  in  this  disease  usually  results  from  some  late  com- 
plication, such  as  bronchopneumonia,  or  from  some  cerebral  accident,  such 
as  hemorrhage,  which  are  direct  results  of  general  paresis  itself.  Al- 
though 639  paretics  died  in  the  New  York  State  hospitals  in  the  year 
ending  September  30,  1914,  only  501,  or  78  per  cent.,  of  these  deaths  were 
reported  as  due  to  general  paresis.  If  the  same  ratio  existed  in  those  dying 
outside  institutions  we  know  that  not  less  than  1,000  patients  with 
general  paresis  died  in  the  State  of  New  York  during  that  year.  How- 
ever, deaths  from  this  cause  are  much  more  likely  to  be  reported  as  due 
to  complicating  disorders  outside  institutions  than  in  them,  where  the 
mental  condition  naturally  attracts  the  most  attention.  The  mental 
symptoms  of  general  paresis  are  so  very  often  subordinate  to  the  physical 
changes  that  admission  to  an  institution  for  the  insane  is-  not  necessary 
in  all  cases  and  still  more  frequently  the  existence  of  the  disease  is 
overlooked  altogether.     It  is  apparent,  therefore,  that  general  paresis  is 

^Goldberger,  Joseph:  "The  Prevention  of  Pellagra,"  Public  Health  Reports, 
October  22,   1915. 

^Lorenz,  William  F. :  "Mental  Manifestations  of  Pellagra,"  Public  Health 
Reports,  February  4,  1916.  - 


U4  MENTAL    HYGIENE 

a  cause  of  many  more  deaths  than  are  attributed  to  it.  Known  cases 
cause  more  deaths  in  New  York  State  than  typhoid  fever.  The  deaths 
from  general  paresis  are  very  largely  grouped  in  the  two  decades  from  40 
to  60,  and  in  this  age-period  one  in  wine  of  the  deaths  among  men  and 
one  in  thirty  of  those  among  women  are  from  this  disease.  The  course  of 
general  paresis  is  usually  from  two  to  five  years.  It  attacks  people  who 
have,  to  all  appearances,  recovered  from  syphilis  and  most  frequently  in 
the  fourth  decade  of  life  when  their  usefulness  to  their  families  and  to 
the  community  is  greatest. 

The  relation  of  syphilis  to  general  paresis  has  long  been  suspected, 
and  even  before  the  discovery  by  Moore  and  Noguchi  of  the  Treponema 
pallida  in  the  cerebral  substance  the  belief  was  general  among  psychia- 
trists that  all  cases  were  due  to  this  cause.  Other  undetermined  factors 
apparently  contribute  to  general  paresis  but  syphilis  is  the  essential 
cause;  without  syphilis  there  could  be  no  general  paresis.  It  is  very 
desirable  to  know  what  proportion  of  cases  of  syphilis  result  in  general 
paresis,  but,  until  recently,  no  satisfactory  studies  had  been  undertaken 
to  determine  this,  and,  on  account  of  the  long  interval  between  infection 
with  syphilis  and  the  development  of  symptoms  of  general  paresis,  it 
seemed  impossible  to  find  a  group  of  population  in  which  such  studies 
could  be  made.  Mattauschek  and  Pilcz  have  reported  {Berliner  Minische 
Woclienschrift,  Feb.  19,  1912)  the  results  of  a  careful  examination  of 
the  histories  of  4,134  officers  of  the  Austrian  Army  who  had  contracted 
syphilis  during  the  period  1880-1890.  They  ascertained  that  4.67  per 
cent,  of  these  officers  developed  general  paresis. 

It  is  a  fact  that  general  paresis  is  a  much  more  frequent  nervous  form 
of  syphilis  than  locomotor  ataxia.  The  course  of  the  latter  disease  is 
from  six  to  eight  times  as  long  as  that  of  general  paresis  and  the  number 
of  persons  living  at  one  time  with  either  disease  is  about  the  same. 

A  relatively  small  proportion  of  other  psychoses  are  directly  due  to 
syphilis.  Men,tal  deterioration  is  associated  with  gummata  of  the  brain 
and  mental  changes  accompany  local  syphilitic  meningitis.  About  one 
per  cent,  of  all  men  admitted  to  hospitals  for  the  insane  and  about  half 
this  proportion  of  women  suffer  from  such  form  of  cerebral  syphilis. 
It  is  impossible  to  estimate  the  part  played  by  syphilis  in  the  causation  of 
other  mental  diseases,  but  it  is  not  to  be  disregarded.  The  train  of 
pathological  processes  commencing  with  arterial  changes  and  culminating 
later  in  organic  changes  in  the  brain  and  with  their  accompanying  men- 
tal disease  is  not  infrequently  started  by  infection  with  syphilis. 

Mental  Deficiency. — Syphilis  has  been  thought  to  be  an  infrequent 
cause  of  mental  deficiency.  Tredgold  says  that  only  2.5  per  cent,  of  his 
cases  presented  undoubted  marks  of  syphilis,  while  Fletcher  Beach 
found  syphilis  in  only  1.17  per  cent,  of  2,380  mentally'  defective  persons 
examined  in  London.     These  percentages  were  ascertained  before  the 


MENTAL   HYGIENE  345 

general  use  of  the  Wassemiann  test.  An  examination  of  400  patients  in 
the  asylums  of  the  Metropolitan  Asylum  Board  in  London  in  1913  by 
Gordon  ^  showed  positive  reactions  in  31.8  per  cent,  of  cases  with  evi- 
dence of  gross  brain  disease  and  in  11.9  per  cent,  of  cases  without  such 
evidences.  In  this  country  Atwood  -  found  positive  reactions  in  15  per 
cent,  of  all  cases  and  Haines  ^  founds  in  an  examination  of  365  children 
in  reform  schools  in  Ohio,  no  larger  percentage  among  the  mentally 
defective  than  among  the  normal  children.  Twenty  per  cent,  of  all  cases 
examined  gave  a  positive  Wassemiann  reaction.  It  appears  very  probable 
that  the  percentages  of  mental  deficiency  attributed  to  syphilis  represent 
only  the  prevalence  of  syphilis  among  the  group  of  the  population  from 
which  the  mentally  defective  enter  American  institutions.  The  neuro- 
pathology of  mental  deficiency  rarely  suggests  syphilis — either  heredi- 
tary or  acquired — and  it  seems  likely  that  this  is  not  a  relatively  impor- 
tant cause  of  mental  deficiency.  Tredgold  believes  that  the  existence  or 
absence  of  neuropathic  heredity  determines  whether  or  not  hereditary 
syphilis  will  result  in  mental  deficiency.  The  findings  in  not  a  few  cases 
of  so-called  "syphilitic  mental  deficiency"  show  quite  clearly  that  juvenile 
general  paresis  was  the  true  condition  present. 

Preventive  Measures. — The  prevention  of  general  paresis  and  other 
mental  diseases  which  depend  directly  upon  syphilis  can  be  accomplished 
only  by  preventing  well  persons  from  contracting  syphilis  and  by  the 
early  and  effective  treatment  of  syphilitics  so  that  this  late  and  fatal 
manifestation  may  be  averted.  There  are  enough  cases  of  juvenile 
general  paresis  to  make  this  danger  an  additional  reason  for  inducing 
persons  with  syphilis  to  abstain  from  marriage.  The  prevention  of 
syphilis  is  considered  elsewhere  (Section  I,  Chapter  I).  It  is  a  rather 
surprising  fact  that  many  of  those  actively  engaged  in  the  campaign 
against  venereal  disease  are  quite  unaware  of  the  prevalence  of  general 
paresis  or  that  it  depends  upon  previous  infection  with  syphilis.  The 
psychiatrist  has  nothing  to  add  except  the  impressive  statistics  showing 
the  great  prevalence  of  this  terrible  result  of  syphilis  and  the  earnest 
recommendation  that  opportunities  for  the  early  and  thorough  treatment 
of  syphilis  should  be  greatly  increased.  In  the  larger  question  of  the 
control  of  prostitution,  which  is  interwoven  with  that  of  venereal 
prophylaxis,  the  information  being  gleaned  by  psychiatrical  study  of 
the  springs  of  human  conduct  may  some  day  give  information  which 
will  enable  mankind  to  understand  prostitution  better  and  deal  with  its 
causes  more  rationally. 

Increased  provision  for  the  mentally  defective  will  aid  in  limiting 

prostitution,  for  it  has  been  shown  that  the  feeble-minded  form  a  pro- 

^  Gordon,  J.  L. :     Lancet,  September  20,  1913. 

^Atwood,  Cliarles  E.:     Journal  of  the  Amer.  Med.  Assn.,  Vol.  56   (1911). 
^Haines,   Thomas   H. :      "The   Incidence  of    Syphilis  Among  Juvenile  Delin- 
quents," Journal  of  the  American  Medical  Association,  January  8,  1916, 


346  MENTAL    HYGIENE 

lific  source  for  the  recruiting  of  prostitutes.  When  tlie  relation  of 
syphilis  to  the  causation  of  mental  deficiency  becomes  better  defined  it 
may  be  shown  that  not  only  will  provision  for  the  mentally  defective 
decrease  the  prevalence  of  syphilis,  but  the  control  of  syphilis  will  de- 
crease in  some  measure  the  amount  of  mental  deficiency. 

OTHER  INFECTIONS 

Psychoses. — Other  infectious  diseases,  notably  typhoid  fever,  influ- 
enza,, malarial  fever,  erysipelas,  and  septicemia  (particularly  from  uterine 
infection),  furnish  a  small  number  of  cases  of  mental  disease.  From  1 
to  2  per  cent,  of  all  first  admissions  are  mental  disease  belonging  to  the 
"infective-exhaustive"  group,  in  which  elevation  of  temperature,  exhaus- 
tion, and  poisoning  of  the  nervous  centers  by  bacterial  toxins  act  as  direct 
causes.  The  proportion  of  women  in  psychoses  in  this  group  is  about 
twice  that  of  men,  the  difference  being  due  to  the  number  of  puerperal 
cases.  In  other  psychoses,  acute  infections  often  play  a  very  important 
if  secondary  part,  apparently  "liberating"  an  attack  or  adding  just  enough 
stress  to  make  the  onset  of  the  psychosis  possible.  Alcohol  and  the 
infections  exert  an  influence  together  sometimes  which  neither  cause 
can  exert  alone.  It  has  been  stated  that  tuberculosis  is  the  cause  of  a 
definite  psychosis,  but  there  seems  to  be  no  evidence  upon  which  to  base 
this  belief.  Exhaustion  psychoses  occur  in  this  disease  as  in  typhoid 
fever. 

Mental  Deficiency. — The  growing  realization  of  the  importance  of 
heredity  as  a  cause  of  mental  deficiency  has  rather  obscured  other  factors, 
but  damage  to  the  brain  seems  responsible  for  a  considerable  number  of 
cases  of  mental  deficiency  in  families  where  there  is  no  evidence  of 
neuropathic  heredity  or  mental  deficiency.  Where  cerebral  hemorrhage 
occurs  in  the  course  of  an  infectious  disease  in  infancy  or  early  childhood 
mental  deficiency  may  be  one  of  the  results  and  there  is  excellent  evidence 
■ — both  clinical  and  pathological — that  bacterial  toxins  may  permanently 
injure  the  brain  cells  or  prevent  their  development.  After  cerebrospinal 
meningitis  mental  deficiency  may  result  from  gross  damage  to  the  brain 
or  from  interference  with  development.  Local  meningitis  from  middle- 
ear  disease  following  scarlet  fever  or  measles  may  also  cause  mental 
deficiency.  Serious  impairment  of  the  special  senses  as  a  result  of 
damage  to  the  cranial  nerves  may  cause  mental  deficiency  through 
deprivation.  The  large  number  of  cases  which  have  been  attributed  to 
the  infections  of  childhood  upon  insufficient  evidence  while  really  due 
to  unmistakable  heredity  has  led  to  an  undue  skepticism  regarding 
the  influence  of  causes  acting  after  birth.  Goddard  casts  doubt  upon 
the  existence  of  such  cases,  except  those  resulting  from  cerebrospinal 
meningitis,  by  raising  the  question  as  to  why  such  diseases  as  measles  and 


MENTAL    HYGIENE  347 

whooping-cough  result  in  mental  deficiency  in  some  cases  and  not  in 
others.  Even  in  those  cases  in  which  a  cerebral  hemorrhage  has  occurred 
during  a  paroxysm  of  whooping-cough,  he  asks  "Why  does  this  child's 
blood  vessel  burst  when  others  do  not?"  and  answers  his  question  by 
saying  that  it  can  only  be  because  there  is  "a  constitutional  weakness  of 
the  vascular  system  which  allows  of  a  rupture  here  and  not  in  other 
instances."  It  would  be  nearly  as  unreasonable  to  assert  that  heredity 
determines  whether  a  typhoid  fever  patient  has  an  intestinal  perforation 
or  does  not  or  whether  another  has  a  lymphangitis  or  not.  The  fact 
is  that  any  organ  of  the  child  can  be  affected  in  its  integrity  or  its 
development  by  the  infectious  diseases  through  which  he  passes,  and  yet 
we  are  asked  to  believe  that  one  of  the  most  delicate  of  them  all  can  only 
be  permanently  injured  if  heredity  has  already  laid  a  foundation  of 
predisposition.  It  is,  of  course,  very  desirable  to  know  the  mental 
condition  of  children  before  the  occurrence  of  these  accidental  causes  of 
mental  deficiency  in  order  that  errors  in  diagnosis  may  be  avoided. 

Preventive  Measures. — The  prevention  of  the  mental  diseases  and 
defects  dependent  upon  infections  consists  in  the  prevention  of  the  in- 
fectious diseases.  The  prevention  of  the  infectious  diseases  is  the  task  of 
general  hygiene  and  preventive  medicine  and  is  the  chief  theme  of  this 
work.  More  careful  methods  of  treating  febrile  diseases  and  especially 
appreciation  of  the  full  significance  of  delirium  will,  among  other  bene- 
ficial effects,  lessen  by  a  small  but  appreciable  number  of  cases  of  mental 
diseases  and  mental  defect  which  upon  injury  to  the  brain  in  such  affec- 
tions. Those  individuals  who  respond  very  easily  to  delirium  should 
receive  most  careful  attention.  Hydrotherapeutic  measures  will  prob- 
ably tend  to  prevent  cerebral  edema  and  changes  in  the  brain  cells. 

HEAD   INJURIES 

Psychoses. — A  very  small  number  of  patients  admitted  to  hospitals 
for  the  insane  suffer  from  psychoses  due  directly  to  traumatism  to  the 
brain.  Nearly  all  such  cases  are  men.  Injury  to  the  brain  often  seems  to 
have  a  marked  effect  in  precipitating  psychoses  in  alcoholics  and  some- 
times in  other  psychoses  dependent  primarily  upon  other  causes.  Street 
accidents  and  accidents  from  unprotected  machinery  are  responsible  for 
many  head  injuries,  l^ut  by  far  the  greater  number,  especially  in  alco- 
holics, are  due  to  the  too  vigorous  and  indiscriminate  use  of  policemen's 
clubs.  The  efficient  regulation  of  traffic  and  the  "safety  first"  are  appa- 
rently diminishing  the  number  of  traumatic  cases  quite  rapidly,  but  it  is 
possible  also  that  better  methods  of  psychiatrical  study  are  assigning 
some  of  the  cases  previously  thought  to  be  traumatic  to  other  more  ap- 
propriate clinical  groups. 

Mental  Deficiency. — Injury  to  the  brain  or  cerebral  hemorrhage  oc- 


348  MENTAL    ITYOrENE 

curring  during  birth  may  be  looked  upon  as  a  cause  of  mental  deficiency 
which  iS;,  to  a  certain  extent,  preventable.  It  is  not  quite  as  easy  to 
determine  whether  or  not  brain  injuries  during  infancy  and  early  child- 
hood are  the  essential  cause  of  mental  deficiency  unless  retardation  or 
cessation  in  the  mental  development  of  the  child  is  very  apparent  after 
the  injury,  for  extensive  damage,  with  definite  focal  signs,  is  often  unac- 
companied by  mental  defect  and  a  history  of  head  injury  or  some  sort 
or  another  is  almost  always  given  by  relatives  in  cases  which  are  clearly 
hereditary.  Nevertheless,  there  are  not  a  few  instances  in  which  it 
seems  beyond  doubt  that  mental  deficiency  is  caused  in  this  way. 

Preventive  Measures. — The  frequency  of  traumatic  psychoses  is 
hardly  great  enough  to  warrant  suggesting  specific  measures  of  preven- 
tion, but  the  "safety  first"  movement  will  prove  useful  here  as  well  as 
in  other  imsuspected  directions.  The  fairly  numerous  cases  of  brain 
injury  due  to  the  use  of  policemen's  clubs  might  be  lessened  if  police 
officials  were  given  an  idea  of  the  thinness  of  the  human  skull  and  were 
shown  a  few  persons  with  traumatic  psychoses  in  our  hospitals  for  the 
insane. 

Injuries  to  the  brain  at  birth  depend  in  some  part  at  least  upon 
careless  obstetric  work  and  the  long  labors  which  the  ignorant  manage- 
ment of  childbirth  by  midwives  entails. 

MENTAL   CAUSES 

Important  recent  additions  to  our  knowledge  concerning  the  psychol- 
ogy of  mental  diseases  have  brought  about  radical  changes  of  opinion  as 
to  the  part  played  by  mental  causes.  The  statistical  tables  of  hospital 
reports  have  always  listed  as  etiological  factors  "grief,"  "worry,"  "death 
of  a  relative,"  "fear,"  "remorse,"  "fright,"  and  "disappointment  in  love." 
Large  numbers  of  cases  have  been  attributed  to  such  causes  as  these 
without  any  knowledge  as  to  the  manner  in  which  they  operated.  It  has 
been  pointed  out  that  they  really  represent  little  more  than  a  catalogue 
of  the  untoward  circumstances  which,  to  a  greater  or  less  degree,  shadow 
the  life  of  every  individual  and  that  the  proportion  of  persons  who 
develop  mental  disease  in  consequence  must  be  extremely  small.  This 
difficulty  has  been  disposed  of  by  the  assumption  that  if  only  a  few  of 
those  who  are  exposed  to  such  adversities  develop  mental  disease,  an 
inherited  neuropathic  predisposition  must  determine  this  unfortunate 
outcome.  Eecent  studies,  however,  especially  those  which  have  followed 
the  enormously  important  discoveries  of  Sigmund  Freud,  have  shown 
that  the  significance  of  such  factors  can  be  estimated  only  by  under- 
standing the  part  which  they  play  in  the  mental  lives  of  the  individuals 
affected.  Many  factors  which  have  been  listed  as  causes  of  mental 
disease  are  now  known  to  be  merely  striking  circumstances  attending 


MENTAL    HYGIENE  349 

the  progress  of  psychoses  or  surface  indications  of  deep-seated  conflicts 
in  personal  life. 

The  psychoses  and  the  neuroses  are  often  clearly  seen  to  be  attempts 
at  adaptation — disastrous  to  be  sure  in  most  instances,  but  sometimes 
the  only  attempt  possible  under  the  circumstances.  They  represent,  in 
many  cases,  flights  into  the  unreal  from  intolerable  situations  in  the 
life  of  the  individual.  Biologically,  these  results  may  not  always  be  the 
most  unsatisfactory  solution,  for  they  often  prolong  life.  The  psychosis 
is  not  infrequently  an  alternative  to  suicide.  As  society  estimates  suc- 
cess, however,  they  are  failures  in  adaptation.  It  would  be  difficult, 
even  if  this  entire  chapter  were  available  for  the  purpose,  to  describe 
the  operation  of  mental  mechanisms  which  lead  in  the  one  case  to  such  a 
result  and  in  others  to  a  compensatory  set  of  reactions  which  maintain 
the  mental  health  and  efficiency  of  the  individual.  One  person  deals  with 
an  intolerable  situation  by  taking  refuge  in  silence,  inaccessibility  and 
refusal  to  eat  and,  in  consequence,  goes  to  a  hospital  for  the  insane, 
while  another  devotes  himself  to  altruistic  work  which  not  only  increases 
his .  self -esteem  and  heals  the  hurts  of  an  unkind  fate,  but  at  the  same 
time  benefits  his  fellow-men.  The  explanation  of  such  diiferences  in 
reactions  to  events  would  lead  us  deeply  into  analysis  of  the  personality 
and  the  psychology  of  mental  diseases.  It  is  necessary,  however,  in  order 
that  some  preventive  principles  may  be  presented,  to  outline  in  a  very 
general  way  the  conception  of  mental  conflict  which  underlies  the  newer 
attitude  toward  the  mental  causes  of  mental  disease. 

In  order  to  gain  an  idea  of  the  place  which  mental  conflicts  occupy 
in  the  life  of  the  individual  it  is  necessary  to  look  upon  existence  as  a 
continuous  series  of  adjustments — some  simple  and  some  highly  difficult 
and  complex — between  fundamental  instinctive  demands,  on  the  one 
hand,  and  the  requirements  of  society  on  the  other.  In  the  young 
infant,  the  care  given  by  others  makes  these  adjustments  unnecessary. 
If  this  care  is  not  forthcoming  the  individual  perishes,  as  there  exists  no 
mechanism  by  which  adjustments  can  be  made.  In  the  child,  the  adjust- 
ments required  are  few  and  relatively  easy,  but  as  life  unfolds  they  in- 
crease in  number  and  complexity.  The  capacity  for  making  these  adjust- 
ments (upon  which  successful  living  depends)  varies  greatly  in  difi'erent 
individuals,  partly  as  a  result  of  differences  in  the  inherent  capacity  for 
adjustment  and  partly  as  a  result  of  failure  to  establish,  through  experi- 
ence and  education,  the  kind  of  mental  mechanisms  most  likely  to  aid 
in  making  satisfactory  adjustments.  The  first  factor  is  beyond  our 
present  control  in  the  individual — heredity  has  already  determined  it — 
the  second,  we  are  coming  to  believe,  may  be  greatly  modified  by  directing 
attention  to  education  and  experience. 

These  never-ending  conflicts  between  the  requirements  of  reality  and 
the  demands  of  instincts  determine  behaviour — both  individual  and  so- 


350  MENTAL    HYGIENE 

eial.  The  sex  instinct  is  involved  most  frequently  and  most  profoundly 
in  these  conflicts.  According  to  Freud,  it  is  directly  or  indirectly  in- 
volved in  all.  It  is  probably  more  within  the  bounds  of  moderation 
to  consider  these  conflicts  as  involving  any  of  the  fundamental  in- 
stincts, the  sex  instinct  most  often.  It  can  readily  be  seen  that  the 
necessity  for  continuous  adjustments  between  the  powerful  and  unalter- 
able urgings  of  the  instincts  and  the  constantly  changing  requirements 
of  daily  life  presents  innumerable  opportunities  for  mishaps  or  for  the 
establishment  of  habitual  reactions  which  are  undesirable.  Few  indi- 
viduals achieve  conspicuous  success  or  conspicuous  failure  in  this  great 
struggle  which  makes  up  the  most  of  mental  life. 

A  great  deal  of  conflict  is  averted  through  the  intervention  of  cus- 
toms which  society,  quite  unaware  of  their  real  purpose,  has  established 
to  direct  effort  at  adjustment  along  paths  of  little  resistance.  Traditions 
and  codes  which  have  long  presented  opportunities  for  unsuccessful  con- 
flict are  constantly  in  process  of  modification.  On  the  other  hand,  how- 
ever, new  developments  in  social  life  bring  about  new  and  complex 
situations.  There  seems  to  be  evidence  that  the  requirements  of  ad- 
vancing civilization  make,  upon  the  whole,  greater  demands  upon  the 
capacity  for  adjustment  than  do  those  of  more  primitive  social  states. 
As  Bernard  Hart  has  pointed  out,^  many  social  conventions  might 
well  be  modified  so  as  to  provide  alternatives  to  the  ruthless  decision 
that  all  individuals  who  cannot  live  within  the  narrow  limits  assigned  by 
conventional  and  purely  arbitrary  standards  of  conduct  must  be  segre- 
gated from  society  or  even  prohibited  from  reproducing  their  kind. 

Preventive  Measures. — There  are  special  groups  of  the  population 
in  special  need  of  assistance  in  making  the  adjustments  to  their  en- 
vironment upon  which  successful  living  depends.  The  idiot,  like  the 
young  infant,  is  incapable  of  making  even  the  simplest  adjustments 
to  the  world  about  him  and  would  perish  if  others  did  not  make  for 
him  the  adaptations  which  he  cannot  make  for  himself.  Defectives  of 
higher  grade  can  make  relatively  simple  adjustments  and  in  an  en- 
vironment carefully  arranged  with  reference  to  the  extent  of  their  ad- 
justing capacity  happy  and  useful  living  is  possible.  As  Dr.  C.  Macfie 
Campbell  has  pointed  out,^  "The  contented  and  industrious  worker  in 
an  institution  for  the  feeble-minded  may  have  exactly  the  same  consti- 
tution as  his  brother  who  is  in  jail  for  repeated  criminal  acts."  It  is 
not  with  the  mentally  defective,  however,  that  this  phase  of  mental 
hygiene  chiefly  concerns  itself.  Adjustments  cannot  be  made  by  some- 
body else  for  one  who  is  not  mentally  defective;  they  must  be  made  by 
the  individual  and  all  that  others  can  do  is  so  to  train  and  direct  his 

^Hart,  Bernard:     "The  Psychology  of  Insanity,"  Cambridge,  1914. 
"Campbell,  C.  Macfie:      "Fundamental  Causes  of  Dependency,"  Mental  Hy- 
giene, Vol.  1,  No.  1. 


MENTAL   HYGIENE  351 

activities  that  he  will  develop  good  mental  reactions  and  so  to  aid  him 
in  selecting  his  environment  that  he  will  live  upon  the  level  which,  for 
him,  offers  the  best  opportunities  for  efficient  and  happy  existence. 
The  practical  application  of  these  broad  principles  obviously  depends  upon 
the  recognition  of  the  capacities  and  limitations  of  the  individual.  As  the 
reactions  which  determine  success  or  failure  in  life  are  very  largely 
established  in  childhood,  it  is  to  the  child  that  preventive  measures  must 
chiefly  be  applied. 

The  enormous  increase  of  interest  in  the  mental  life  of  childhood 
is  leading  to  the  recognition  at  a  much  earlier  period  than  formerly  of 
those  factors  which  endanger  mental  health.  Education  must  be  funda- 
mentally altered  to  fit  the  needs  of  subnormal  children  and  those  with 
special  difficulties  of  adaptation.  So  numerous  and  so  disastrous  are 
the  results  of  failure  to  make  the  modifications  in  teaching  which  these 
children  require  that  the  whole  educational  system  might  well  be  ex- 
amined with  reference  to  their  special  needs.  Constant  and  increasing 
efforts  should  be  made  to  determine  the  individual  requirements  of 
school  children  and  the  attention  of  the  best  educators  should  be  given 
to  devising  means  for  furnishing  such  children  with  an  equipment  which 
will  fit  the  individual  child  to  live  successfully,  the  average  child  being, 
for  the  moment^  forgotten.  Special  classes  exist  now  only  for  mentally 
defective  children.  They  should  be  provided  for  all  hinds  of  atypical 
children,  intellectual  defect  representing  only  one  and  not  perhaps  the 
most  important  cause  of  imperfect  mental  adjustment. 

Of  the  utmost  importance,  in  laying  the  foundations  in  childhood  for 
mental  reactions  which  in  later  life  may  prevent  psychoses,  is  the  culti- 
vation of  a  frank  emotional  attitude.  Personal  difficulties  should  never 
be  dissembled  but  always  faced  in  their  reality.  Children  do  not  feel 
the  same  emotions  as  adults  and  the  efforts  of  parents  and  teachers  to 
make  them  feel  or  "act  as  if  they  felt"  sympathy  or  sorrow  or  remorse 
when  they  do  not,  simply  plants  the  seeds  for  unreal  emotional  attitudes 
in  later  years.  Eecourse  to  the  unreal  is  the  habit  which  it  is  mental 
hygiene's  great  task  to  prevent.  It  is  much  better  to  have  a  child  do 
something  to  relieve  suffering  than  to  induce  him  to  act  as  if  he  felt  an 
emotion  which  in  reality  he  does  not.  Thus  the  objectivity  of  life  will 
be  intensified  and  this  is  perhaps  the  chief  object  of  mental  hygiene. 
Lyman  Wells  has  said' (what  all  psychiatrists  know)^  that  self-love  and 
self-consciousness  constitute  the  great  fountain-head  of  mental  mal- 
adaptations.  No  other  measures  will  more  surely  prevent  their  growth 
than  the  frank  facing  of  actuality  in  childhood  when  mistakes  can  be 
acknowledged  without  loss  of  self-respect  and  rectified  without  difficulty. 
It  is  especially  important  that  a  frank  emotional  attitude  toward  sex 
should  be  established.    The  movement  for  instruction  in  sex  hygiene  has 

*  Wells,  Lyman  F.:     "Mental  Adaptation,"  Mental  Hygiene,  Vol.  1,  No.  1. 


352  MENTAL   HYGIENE 

for  its  chief  objects  the  control  of  venereal  disease  and  the  prevention  of 
sexual  immorality.  If  this  movement  grows  upon  a  rational  and  strong 
foundation,  these  benefits  will  be  far  outweighed  by  its  effect  upon  the 
general  attitude  toward  sexual  difficulties. 

Preventive  measures  in  this  field  of  mental  hygiene  embrace  a  wide 
range  of  activities.  All  of  them  could  hardly  be  enumerated  here  but  the 
more  fundamental  ones  may  with  advantage  be  summed  up,  even  at  the 
risk  of  being  didactic,  in  these  injunctions :  determine  the  inherent  capac- 
ity of  each  individual  to  make  adjustments  to  his  environment;  realize 
that  the  cause  of  most  mal-adjustments  in  later  life  arise  in  the  early 
years  of  childhood ;  aid  each  individual  to  find  the  level  at  which  he  can 
live  most  successfully ;  cultivate  a  frank  emotional  attitude,  especially  in 
matters  relating  to  sex ;  deal  with  actualities  and  so  not  evade  difficulties 
or  transform  them  into  a  false  situation;  cultivate  an  objective  view  of 
life  enjoying  to  the  full  art,  literature,  music,  and  other  desirable  means 
of  escaping  into  the  world  of  unreality,  but  at  the  same  time  realizing 
their  real  nature ;  distribute  interest  throughout  a  wide  range  of  activi- 
ties, reserving  an  important  place  for  those  which  do  not  contribute 
directly  to  self-gratification  but  which  benefit  others. 

It  is  of  the  utmost  importance  in  this  field  of  mental  hygiene  to 
remember  that  individuals  in  need  of  assistance  in  making  difficult  ad- 
justments are  rarely  able  to  understand  the  situation  or  take  the  steps 
needed  to  bring  about  successful  adjustments  without  the  help  of  others 
and  that  those  who  give  such  help  must  possess  psychiatrical  knowledge. 
This  emphasizes  the  importance  of  mental  clinics  where  such  advice  and 
guidance  can  be  obtained.  Every  university  should  have  a  department 
of  mental  hygiene  in  charge  of  a  well-qualified  psychiatrist  whose  chief 
duty  should  be  to  help  students  to  understand  and  deal  with  their  per- 
sonal problems.  Every  city  school  system  should  have  such  a  department 
and  should  maintain  school  clinics  in  charge  of  competent  psychiatrists^ 
for  the  examination  and  treatment  of  all  children  experiencing  special 
difficulties.  If  these  recommendations  seem  radical  and  expensive,  it 
is  only  necessary  to  consider  the  enormous  loss  through  mental  diseases 
and  other  mal-adjustments  which  depend  upon  the  causes  which  we  have 
been  considering  and  then  remember  that  this  is  the  one  group  of  mental 
affections  in  which,  at  the  present  time,  practically  no  efforts  are  being 
made  for  prevention. 

ECONOMIC   FACTORS 

Unemployment,  overwork,  congestion  of  population,  child  labor,  and 
the  hundred  economic  causes  which  increase  the  stress  of  living  for  the 
poor  are  often  contributing  factors  in  the  production  of  mental  diseases. 
Weaknesses  in  constitutional  make-up — defects  in  the  armor  of  per- 
sonality— are  disclosed  under  the  stress  of  such  conditions,  but  might 


MENTAL    HYGIENE  353 

have  remained  undiscovered  under  happier  circumstances.  All  that  can 
be  said  of  the  prevention  of  such  causes  is  that  everything  which  makes 
for  the  betterment  of  those  upon  whom  the  stress  of  living  falls  heaviest 
will  save  many  from  mental  disease.  If  the  operation  of  these  powerful 
causes  cannot  be  prevented,  those  who  are  most  likely  to  be  harmed  might, 
perhaps,  be  shielded  a  little  if  the  special  danger  which  they  face  were 
more  generally  known. 

IMMIGRATION 

No  consideration  of  the  preventable  causes  of  mental  diseases  in  this 
country  would  be  complete  without  reference  to  this  important  element 
in  our  national  life.  It  is  a  question  peculiar  to  the  United  States.  Dur- 
ing the  last  95  years  32,027,424  immigrants  have  come  to  this  country.^ 
This  vast  migration  has  no  parallel  in  history.  In  some  states  the  incre- 
ment to  the  population  from  immigration  every  year  exceeds  that  from 
births.  Under  such  conditions  movements  such  as  those  directed  against 
alcohol,  heredity,  or  the  economic  causes  of  insanity  are  feeble  in  their 
immediate  effects  compared  with  a  thorough  sifting  of  applicants  for 
admission  while  they  are  still  at  our  threshold.  We  have  the  absolutely 
unquestioned  right  to  require  any  reasonable  tests  which  can  be  proposed, 
and  yet  the  present  immigration  law  results  in  the  mental  examination 
of  the  smaller  portion  of  the  million  immigrants  who  seek  admission  each 
year.  There  is  no  provision  whatever  requiring  immigrants  to  present 
certificates  from  responsible  authorities  at  home,  testifying  to  their  free- 
dom from  mental  disease.  These  great  numbers  of  immigrants,  30  per 
cent,  of  the  adults  illiterate  and  less  than  20  per  cent,  with  any  trade, 
are,  without  adequate  mental  examination  or  selection,  projected  into 
our  most  congested  centers  of  population,  to  bear,  during  their  first 
years  in  America,  as  severe  stress  as  any  group  of  population  can  be 
called  upon  to  endure.  One  result  is  that  they  are  found  in  larger  num- 
bers in  our  hospitals  for  the  insane  than  their  ratio  to  the  whole  popula- 
tion warrants.  Hundreds  have  to  be  returned  during  the  first  year  for 
mental  disease  due  to  causes  which  existed  before  their  arrival.  In  the 
succeeding  years  the  proportion  rises  and  in  the  next  generation  and  the 
one  succeeding  it  we  shall  doubtless  reap  the  harvest  for  which  our  present 
policy  is  sowing  the  seed.  It  can  be  earnestly  asserted,  after  long  study  of 
this  question,  that  no  measures  for  the  control  of  mental  diseases  and 
mental  deficiency  which  have  yet  been  suggested  can  prove  so  efficacious 
as  artificial  selection  of  additions  to  our  population  on  the  vast  scale 
which  an  adequate  mental  examination  of  immigrants  would  permit. 
This  is  a  measure  of  practical  eugenics  which  can  be  applied  successfully 
now  and  one  in  which  we  shall  not  have  to  wait  a  generation  to  note  the 
effect.  As  Professor  E.  DeC.  Ward  has  said,  "It  is  merely  a  question 
*  January  1,  1820,  to  June  30,  1915. 
13 


354  MENTAL   HYGIENE 

whether  we  or  foreign  steamship  agents  shall  select  the  parents  of  future 
generations  of  Americans."  The  provisions  of  the  federal  immigration 
law  which  deal  with  the  exclusion  of  insane  immigrants  are  in  need  of 
thorough  and  immediate  revision  and  the  enforcement  of  the  law  should 
receive  the  attention  which  its  importance  deserves. 

We  have  been  far  too  careless  of  the  welfare  of  recently  landed  im- 
migrants. There  seems  to  be  a  general  impression  that,  however  unsani- 
tary their  surroundings  or  however  heavy  may  be  the  burdens  placed  upon 
them,  immigrants  are  in  some  way  fitted  for  such  hardships,  either  by 
nature,  or  through  previous  experiences  in  their  homes.  Of  course,  this 
assumption  is  without  justification  and  it  is  time  that  the  social,  eco- 
nomic, physical,  and  moral  welfare  of  these  newcomers  be  given  the 
earnest  attention  of  the  federal  and  state  governments  and  of  societies 
and  individuals.  By  so  doing  something  may  be  done  to  lessen  the  dis- 
proportionate prevalence  of  mental  disease  in  this  large  group  of  our 
population. 

AGENCIES   AVAILABLE    FOR   THE   APPLICATION    OF   PREVENTIVE 

MEASURES 

It  is  possible  to  mention  only  very  briefly  some  of  the  agencies  which 
can  be  utilized  in  the  application  of  preventive  measures. 

Hospitals  for  Mental  Disease. — A  very  large  proportion  of  the  per- 
sons with  mental  disease  in  any  state  will  be  found  under  treatment  in 
public  institutions.  This  is  not  the  case  with  other  diseases,  sufferers 
from  which  are  widely  scattered,  in  their  homes,  at  work,  and  in  hos- 
pitals. This  fact  makes  the  hospital  for  the  insane  seem  the  logical  place 
in  which  preventive  measures  should  originate.  As  Adolf  Meyer  ^  has 
said :  "A  modern  hospital  must  get  together  the  material  with  which 
to  reconstruct  the  patient's  life."  "It  must  be  in  touch  with  the  patient's 
home.  .  .  ." 

Every  hospital  for  the  insane  should  maintain  a  dispensary  or  more 
than  one  if  it  has  a  large  district.  To  these  dispensaries,  if  they  are 
skilfully  conducted  with  their  broadest  aims  constantly  in  mind,  will 
come  incipient  cases,  "borderland"  cases,  those  who  have  had  previous 
attacks  of  mental  disease,  and  relatives  seeking  advice.  Such  dis- 
pensaries— and  several  states  have  already  instituted  them — afford  rich 
opportunities  for  the  practical  application  of  preventive  measures  and 
for  the  dissemination  of  information.  Members  of  the  hospital  staffs 
should  also  engage  in  field  work  in  the  districts  from  which  their  hospital 
receives  its  patients.  Talks  on  the  preventable  causes  of  mental  disease, 
the  advantages  of  earlier  treatment,  and  the  necessity  of  considering 
insanity  as  a  disease  and  not  a  crime  can  be  given  by  such  medical  field 

^  Meyer,  Adolf:  "Organizing  the  Community  for  the  Protection  of  Its  Mental 
Life,"  The  Survey,  September  18,  1915. 


MENTAL    HYGIENE  355 

workers  in  schools  and  churches  and  before  clubs  and  societies.  Such 
talks  should  be  supplemented  by  illustrated  descriptions  of  modern 
methods  of  caring  for  the  insane  and  promoting  their  happiness  and 
comfort.  It  is  usual  for  citizens  to  have  a  local  pride  in  their  hospital 
as  a  public  institution,  and  this  will  often  insure  interest.  Every  such 
lecturer  will  be  quite  sure  to  have  the  relatives  or  friends  of  some  of 
his  patients  among  his  hearers.  Such  field  work  by  physicians  should 
be  supplemented  by  that  of  well-trained  social  service  workers  perma- 
nently attached  to  the  institution. 

The  hospital  should  also  be  the  center  for  instruction  in  clinical 
psychiatry  in  the  community.  The  great  wealth  of  clinical  material  in 
a  large  hospital  should  be  utilized  to  the  fullest  extent  if  a  medical 
school  is  near  enough.  It  is  believed  that  better  knowledge  of  mental 
diseases  in  this  country  may  also  be  brought  about  by  developing  the 
opportunities  of  the  general  practitioner  for  receiving  instruction.  The 
medical  student  is  often  overburdened,  and  he  has  much  difficulty  in 
deciding  upon  the  relative  value  of  the  matters  presented  to  him.  In 
competition  with  other  branches  of  medicine  psychiatry  is  very  apt  to 
fare  badly,  for  it  is  likely  to  be  regarded  as  a  specialty  of  slight  value 
or  interest  to  one  who  is  about  to  engage  in  general  practice.  The  firm 
establishment  of  the  medical  conception  of  mental  disease  and  the  relega- 
tion of  the  term  "insanity"  to  the  law  courts  will  do  much  to  enhance 
interest  in  psychiatry.  With  the  practitioner  it  is  different,  for  he  is  a 
dull  man  who  does  not  learn  early  in  his  career  that  mental  diseases  are 
frequently  met  with  and  are  very  important  in  many  of  their  relations. 
It  is  a  fact  that,  until  recently,  there  has  been  no  opportunity  in  the 
United  States  for  a  graduate  in  medicine  to  obtain  post-graduate  instruc- 
tion in  psychiatry  unless  he  is  a  member  of  the  staff  of  an  institution  for 
the  insane  or  a  medical  officer  of  one  of  the  government  medical  corps. 

The  hospital  for  mental  diseases  has  many  opportunities  for  instruct- 
ing general  practitioners.  Frequent  medical  meetings  at  the  hospitals 
in  which  clinical  talks  should  have  chief  place,  correspondence  with 
physicians  who  sign  commitment  papers  regarding  interesting  features 
in  the  course  of  their  cases,  invitations  to  necropsies  (which  in  most  small 
communities  will  be  gladly  accepted ) ,  and  consultations  when  patients  are 
about  to  be  discharged,  at  which  suggestions  for  after-care  can  be  made, 
are  all  means  of  interesting  physicians  in  mental  diseases  and  their 
prevention.  All  these  new  tasks,  which  are  certain  to  be  assigned  to 
our  hospitals  for  mental  disease  within  a  few  years,  will  necessitate  addi- 
tional medical  officers,  and  they  make  it  more  necessary  than  ever  that 
clinical  and  laboratory  work  in  these  institutions  should  be  upon  a  high 
plane.  This  means  increased  appropriations,  but  it  is  doubtful  if  a 
state  can  utilize  its  funds  for  a  better  purpose  than  in  fostering  such 
work  for  prevention  of  mental  diseases.     Placed  upon  a  purely  economic 


356  MENTAL    HYGIENE 

basis,  sucli  work  is  immensely  profitable.  It  lias  been  estimated  tliat 
prevention  of  the  admission  of  a  single  patient  each  year  would  yield  a 
total  return  to  a  state  larger  than  the  pay  and  expenses  of  two  social 
service  field-workers  for  a  year. 

The  hospital  for  the  insane  (and  much  that  has  been  said  here 
relates  also  to  institutions  for  the  mentally  defective)  has  also  excellent 
opportunities  for  disseminating  information  among  the  laity  regarding 
the  cause  and  prevention  of  insanity.  Leaflets,  personal  talks,  and  gen- 
eral literature  regarding  these  subjects  will  not  fail  to  interest  those  who 
have  come  to  the  hospital  to  visit  near  relatives. 

Boards  of  Administration  and  Supervision. — In  most  states  the  ad- 
ministration of  institutions  for  mental  disease  and  mental  deficiency 
is  in  some  measure  under  the  control  of  a  central  board.  Such  bodies 
can  do  much  in  the  prevention  of  insanity.  In  many  States  they  can 
require  such  activities  on  the  part  of  the  hospitals  as  have  been  outlined, 
and  in  others  they  can  exert  powerful  moral  influence  in  having  them 
undertaken.  They  can  conduct  statistical  studies  as  to  the  preventable 
causes  of  insanity,  and  secure  wide  distribution  of  the  material  collected. 
They  can  suggest  and  urge  legislation  for  early  treatment  and  for  the 
adoption  of  specific  preventive  measures.  They  can,  particularly  by 
cooperation  with  similar  authorities  in  other  States,  secure  some  re- 
forms in  federal  legislation  regarding  the  exclusion  of  insane  and 
mentally  defective  immigrants,  the  urgent  need  for  w^hich  has  been 
pointed  out. 

Public  Health  Authorities. — No  better  illustration  of  the  fact  that 
mental  hygiene  has  become  one  of  the  recognized  activities  of  health 
authorities  can  be  found  than  the  proposal  to  create  a  division  of  mental 
hygiene  in  the  United  States  Public  Health  Service.  A  bill  to  provide 
such  a  division  is  now  before  Congress.  Several  State  Departments  of 
Health  are  circulating  information  regarding  mental  hygiene  in  their 
work  of  educational  publicity.  Following  the  example  of  the  Department 
of  Preventive  Medicine  and  Hygiene  of  Harvard  Medical  School,  courses 
in  mental  hygiene  are  now  given  in  the  public  health  departments  of  four 
universities.  Special  courses  for  teachers,  nurses  and  other  groups  are 
being  established  throughout  the  country. 

Educational  Authorities. — Under  the  direction  of  state  boards  of 
administration  and  encouraged  by  national  and  state  societies  for  mental 
hygiene,  much  can  be  done  toward  placing  the  education  of  psychopathic 
and  defective  children  upon  a  better  .basis.  These  children  are  now 
chiefly  interesting  to  school  authorities,  for  they  constitute  a  special  class 
and  should  receive  separate  instruction,  both  for  their  own  good  and  the 
good  of  normal  children  whose  progress  is  retarded  on  account  of  the 
excessive  amount  of  time  teachers  must  give  defective  children.  They 
should  have  a  far  greater  interest  for  the  state  than  this,  for  every  child 


MENTAL    HYGIENE  357 

is  a  possible  patient  in  a  hospital  for  the  insane.  It  would  seem  desirable 
for  the  state  to  provide  very  liberally  for  the  study  of  these  children  and 
for  their  training.  To  this  end,  school  clinics  and  special  classes  in  the 
public  schools  should  be  fostered  by  the  state  educational  authorities 
and  even  subsidized  by  the  state  when  desira1)le. 

National  and  Local  Societies  for  Mental  Hygiene. — There  is  a  very 
clearly  defined  field  of  efl:'ort  for  national  and  local  societies  in  the  work 
of  prevention  of  mental  diseases.  As  has  been  indicated,  the  care  of  the 
insane  is,  far  more  than  that  of  any  other  class  of  the  sick,  in  official 
hands.  There  is  besides  a  great  deal  in  the  methods  of  commitment  and 
provisions  for  care  pending  commitment  which  is  regarded  wholly  as  an 
official  matter.  For  this  reason  there  is  decided  need  for  agencies  which 
can  bridge  the  gap  between  the  usual  environment  of  the  patient  and  the 
public  institution  which  is  to  assume  his  care.  A  certain  part  of  the 
social  service  work  which  has  so  useful  a  place  in  the  care  of  the  insane, 
particularly  in  the  period  following  discharge  from  institutions,  should 
be  done  by  workers  under  the  direction  of  institutional  authorities,  but 
there  is  also  a  very  great  deal  which  can  be  done  better  by  societies  co- 
operating with  institutional  authorities  but  not  officially  connected  with 
them.  In  New  York  State  the  "Committee  on  Mental  Hygiene"  of  the 
State  Charities  Aid  Association  has  a  local  committee  in  each  hospital 
district.  Although  after-care  and  efforts  to  improve  the  kind  of  care 
afforded  the  insane  in  that  critical  period  while  commitment  is  pending 
constitute  the  chief  work  of  such  committees,  there  is  often  opportunity 
for  effective  work  in  prevention  especially  in  popular  education  regard- 
ing preventable  causes.  In  Alabama,  California,  Connecticut,  District 
of  Columbia,  Illinois,  Louisianaj  Maryland,  Massachusetts,  North  Caro- 
lina, Ohio,  Pennsylvania,  and  Rhode  Island,  there  are  societies  for  mental 
hygiene  doing  most  useful  work. 

There  is  a  National  Committee  for  Mental  Hygiene,  coordinating 
and,  in  a  measure,  directing  these  local  activities.  This  committee  has 
commenced  studies  of  existing  provisions  for  the  care  of  the  insane  and 
mentally  defective  in  all  the  states,  methods  of  commitment  and  care 
pending  commitment,  the  influence  of  preventable  causes,  etc.  With  a 
carefully  prepared  plan  of  work,  accurate  information  is  being  obtained 
upon  these  matters,  and,  as  fast  as  the  facts  in  the  possession  of  the 
committee  justify  it,  active  work  is  undertaken  for  amelioration  or  pre- 
vention. It  is  believed  that  a  great  deal  can  be  done,  especially  in  the 
direction  of  standardizing  work  for  the  care  of  the  insane  and  the  pre- 
vention of  insanity,  and  in  coordinating  the  efforts  of  the  hospitals,  state 
boards  of  administration  and  some  of  those  organizations  which  (some- 
times unawares)  are  attacking  preventable  causes  of  mental  diseases  and 
mental  deficiency  from  different  angles.  The  National  Committee  aims 
to  stimulate  interest  on  the  part  of  the  federal,  state  and  local  authorities 


358  MENTAL    HYGIENE 

charged  with  health  work  and  the  care  of  the  insane  and  mentally  defec- 
tive and  to  sustain  interest  when  otherwise  it  might  flag.  Standards 
established  in  states  where  advanced  ideas  prevail  are  being  made  known 
in  states  where  there  is  indifference  or  lack  of  progress.  A  central 
"clearing  house"  for  the  collection  and  distribution  of  accurate  informa- 
tion regarding  the  care  and  prevention  of  mental  diseases  and  mental 
deficiency  is  provided.  Earlier  treatment  and  the  transfer  of  care  pend- 
ing commitment  from  the  policeman  to  the  doctor — the  most  urgent 
needs  of  the  insane — are  important  aims  of  this  organization.  The 
lamentable  failure  to  provide  instruction  in  mental  diseases  in  the  medical 
schools  is  being  shown  and  the  means  are  being  suggested  for  remedying 
this  defect  in  medical  education.  It  is  a  fact  that  the  number  of  beds 
in  the  institutions  for  the  insane  in  this  country  is  greater  than  the 
numbers  of  beds  in  all  the  general  hospitals  of  the  United  States.  The 
insane  are,  therefore,  the  most  numerous  class  of  the  sick  receiving  public 
care.  As  such,  they  are  entitled  to  a  much  larger  share  of  the  interest 
of  every  practitioner  than  they  receive.  Progress  in  every  branch  of 
preventive  medicine  depends  chiefly  upon  the  leadership  of  physicians. 
In  this  particular  fleld  there  is  need  of  much  wider  interest  on  the  part 
of  the  medical  profession  than  exists  today.  One  of  the  functions  of 
the  National  Committee  for  Mental  Hygiene  is  to  broaden  and  increase 
this  kind  of  interest. 

CONCLUSION 

The  attempt  has  been  made  to  outline  some  of  the  preventable  causes 
of  mental  diseases  and  mental  deficiency  and  to  indicate,  very  broadly, 
possible  preventive  measures.  It  seems  essential  that,  notwithstanding 
the  complexity  of  some  of  the  questions  involved,  the  prevention  of  mental 
fliseases  and  mental  deficiency  should  be  considered  in  the  general  ad- 
vance which  is  being  made  against  diseases,  for  it  is  very  closely  related 
to  all  the  other  fields  of  preventive  medicine.  Eecent  advances  in  the 
field  of  psychiatry  have  given  grounds  for  encouragement,  for  if  the 
outlook  in  some  directions  is  not  bright  the  accuracy  with  which  the 
part  played  by  certain  causes  is  being  defined  promises  much.  The  fact 
that  it  has  been  definitely  determined  that  there  are  certain  essential 
causes  of  mental  disease  and  mental  deficiency,  and  that  some  of  these 
essential  causes  are  entirely  controllable,  makes  it  imperative  that  pre- 
ventive measures  should  be  energetically  promoted.  At  the  same  time  the 
great  advantages  in  the  promotion  of  mental  efficiency  which  may  result 
from  better  understanding  of  the  nature  and  importance  of  mental  con- 
flicts and  of  the  means  by  which  more  successful  adaptations  may  be 
made,  should  lead  to  developments  in  the  constructive  phases  of  mental 
hygiene  which,  in  the  end,  may  prove  the  greatest  service  to  mankind  of 
this  branch  of  hygiene. 


MENTAL    HYGIENE  359 


REFERENCES 

Reports,  reprints,  bibliographies  on  special  phases  of  mental  hygiene 
and  the  publications  of  that  organization  may  be  obtained  without  cost 
frorri  the  National  Committee  for  Mental  Hygiene,  50  Union  Square,  New 
York  City. 

General  Subject 

Barker,  Lewellys  F. :  "Some  Phases  of  the  Mental  Hygiene  Movement 
and  the  Scope  of  the  Work  of  the  National  Committee  for  Mental  Hy- 
giene," Pub.  No.  4,  Natl.  Com.  Ment.  Hyg.,  November,  1912. 

Clouston,  Sir  Thomas  S. :  "The  Hygiene  of  the  Mind,"  E.  P.  Button 
&  Co.,  New  York,  1909. 

Forel,  August :  "Hygiene  of  Nerves  and  Mind  in  Health  and  Disease," 
G.  P.  Putnam's  Sons,  New  York,  1907. 

Hoch,  August :  "The  Social  Side  of  Psychiatry,"  reprinted  from 
Studies  in  Psychiatry,  Psychiatric  Institute,  New  York  State  Hospitals, 
1915. 

Meyer,  Adolf:  "Organizing  the  Community  for  the  Protection  of  Its 
Mental  Health,"  The  Survey,  Sept.  18,  1915. 

Mullan,  E.  H. :  "Mental  Hygiene,"  Reprint  No.  164,  IT.  S.  Public 
Health  Reports,  Jan.  23,  1914. 

Paton,  Stewart:  "The  World's  Most  Important  Conservation  Prob- 
lem," reprinted  from  Popular  Science  Monthly,  August,  1912. 

Russell,  William  L. :  "The  Mental  Hygiene  Movement,"  reprinted 
from  Medical  Record,  July  20,  1912. 

Salmon,  Thomas  W. :  "Mental  Hygiene  in  the  Widening  Sphere  of 
Preventive  Medicine,"  Albany  Medical  Annals,  March,  1913. 

Mental  Hygiene,  a  journal  published  quarterly  by  the  National  Com- 
mittee for  Mental  Hygiene. 

"Proceedings  of  the  Mental  Hygiene  Conference  and  Exhibit,"  at  the 
College  of  the  City  of  New  York,  Nov.  8-15,  1912. 

"Mental  Hygiene  Number  of  the  New  York  State  Hospital  Bulletin," 
May,  1915. 

Mental  Causes  of  Mental  Disease 

Hart,  Bernard:  "The  Psychology  of  Insanity,"  G.  P.  Putnam's  Sons, 
New  York,  1914. 

Holt,  Edwin  B. :  "The  Freudian  Wish  and  Its  Place  in  Ethics,"  Henry 
Holt  &  Co.,  New  York,  1915. 

Putnam,  James  J.:  "Services  to  be  Expected  from  the  Psychoana- 
lytic Movement  in  the  Prevention  of  Insanity,"  Journal  American  Med. 
Association,  Chicago,  Nov.  28,  1914. 

Wells,  F.  Lyman :    "Mental  Adaptation,"  Mental  Hygiene,  Vol.  I,  No.  1. 

White,  William  A. :  "Mental  Mechanisms,"  Nerv.  &  Ment.  Dis.  Mono- 
graph Series,  No.  8,  Journal  Nerv.  &  Ment.  Dis. 


360  MENTAL   HYGIENE 

Preventahle  Cannes  of  Mental  Disease. 

Abbot,  E.  Stanley :  "Preventable  Forms  of  Mental  Diseases  and  How 
to  Prevent,"  Boston  Med.  &  Surg.  Jour.,  April  20,  1916. 

Cotton,  Henry  A.:  "Home  Problems  in  tlie  Study  of  Heredity  in  Men- 
tal Diseases,"  American  Journal  of  Insanity,  Baltimore,  Md. 

Hoch,  August:  "The  Manageable  Causes  of  Insanity,"  Stale  Hospital 
Bulletin,  September,  1910. 

Kirby,  George  H. :  "Syphilis  and  Insanity,"  reprinted  from  Proceed- 
ings of  Mental  Hygiene  Conference  and  Exhibit,  November,  1912. 

Orton,  Samuel  T. :  "The  Relation  of  Syphilis  to  Mental  Disease," 
Pub.  No.  10,  Massachusetts  Society  for  Mental  Hygiene,  1916. 

Rosanoff,  A.  J. :  "Alcohol  as  a  Cause  of  Insanity,"  reprinted  from 
Woman's  Med,  Journal,  Cincinnati,  June,  1912. 

= :      "The   Prevention    of   Insanity:     Hygiene    of   the    Mind," 

reprinted  from  Medical  Record,  1911. 

Salmon,  Thomas  W. :  "Tvpo  Preventable  Causes  of  Insanity,"  Popular 
Science  Monthly,  May,  1910. 

White,  William  A. :  "Preventive  Principles  in  the  Field  of  Mental 
Medicine,"  Journal  of  American  Puhlic  Health  Association,  Ohio,  1911. 

Prevention  of  Mental  Deficiency. 

Cornell,  W.  S. :  "Method  of  Preventing  Feeble-mindedness,"  Proceed- 
ings National  Conference  of  Charities  and  Correction,  1915. 

Davenport,  C.  B. :  "Origin  and  Control  of  Mental  Defectiveness,"  Pop- 
ular Science  Monthly,  January,  1912. 

Fernald,  Walter  E. :  "What  is  Practicable  in  the  Way  of  Prevention  of 
Mental  Defect?"  Proceedings  of  the  National  Conference  of  Charities  and 
Correction,  Baltimore,  Md.,  1915. 

Goddard,  H.  H. :  "Feeble-mindedness :  Its  Causes  and  Consequences," 
Macmillan  Co.,  1914. 

:  "Elimination  of  Feeble-mindedness,"  Annals  of  the  Amer- 
ican Academy  of  Political  and  Social  Science,  March,  1911. 

Johnstone,  E.  R. :  "The  Prevention  of  Feeble-mindedness,"  Journal  of 
the-  American  Puhlic  Health  Association,  February,  1911. 

Nevp  York  Psychiatrical  Society :  "Outlines  of  a  State  Policy  for 
Dealing  vpith  Mental  Deficiency,"  reprinted  from  Medical  Record,  April  17, 
1915. 

Schlapp,  M.  G. :  "Available  Fields  for  Research  and  Prevention  in 
Mental  Deficiency,"  New  York  State  Journal  of  Medicine,  October,  1915. 

Mental  Hygiene  in  Childhood 

Barker,  Levi^ellys  F. :  "Principles  of  Mental  Hygiene  Applied  to  the 
Management  of  Children  Predisposed  to  Nervousness,"  Pub.  No.  2,  Na- 
tional Committee  for  Mental  Hygiene,  1911. 

Clark,  L.  Pierce:  "Psychopathic  Children,"  N.  Y.  Med.  Journal,  April 
11,  1914. 


MENTAL   HYGIENE  361 

Meyer,  Adolf:  "What  do  Histories  of  Cases  of  Insanity  Teach  IJs 
Concerning  Preventive  Mental  Hygiene  During  the  Years  of  School  Life?" 
Psychol.  Clinic,  June,  1908. 

Terman,  Lewis  M. :  "The  Hygiene  of  the  Child,"  Houghton-Mifflin  Co., 
Cambridge,  Mass.,  1914. 

Williams,  Tom  A.:  "On  the  Management  of  Exceptional  Children," 
New  YorJc  Med.  Jour.,  January  8,  1916. 

Immigration  and  Mental  Hygiene 

Glueck,  Bernard:  "The  Mentally  Defective  Immigrant,"  reprinted 
from  N.^.  Med.  Journal,  Oct.  18,  1913. 

Paton,  Stewart:  Memorandum  on  Immigration  and  Mental  Hygiene, 
presented  to  President  of  the  United  States,  January  22,  1915. 

Salmon,  Thomas  W. :  "Insanity  and  the  Immigration  Law,"  reprinted 
from  N.  Y.  State  Hospital  Bulletin,  November,  1911. 

Williams,  L.  L. :  "The  Medical  Examination  of  Mentally  Defective 
Aliens:  Its  Scope  and  Limitations,"  reprinted  from  American  Journal  of 
Insanity,  October,  1914. 

Williams,  Henry  Smith:  "Immigration  and  the  Prevention  of  In- 
sanity," Mental  Hygiene  Number,  New  YorJc  State  Hospital  Bulletin,  May, 
1915. 

Societies  for  Mental  Hygiene 

Beers,  Clifford  W. :  "Purposes,  Plans  and  Work  of  State  Societies  for 
Mental  Hygiene,"  Pub.  No.  7,  National  Committee  for  Mental  Hygiene, 
July,  1915. 

Stedman,  Henry  R. :  "A  Program  of  Practical  Measures  for  Mental 
Hygiene  Work,"  reprinted  from  Boston  Med.  &  Surg.  Journal,  Yol.  CLXX, 
No.'  6. 


Chapter  vii 

SOME  GENERAL  CONSIDERATIONS 

Sources  of  Infection, — There  are  two  great  sources  of  the  commu- 
nicable diseases  of  man^  viz.:  (1)  man  himself,  and  (2)  the  lower 
animals.  Most  of  the  communicable  diseases  of  man,  especially  those 
which  occur  in  epidemic  form,  are  peculiar  to  man.  This  is  the  case 
with  typhoid  fever,  cholera,  leprosy,  malaria,  yellow  fever,  syphilis, 
mumps,  measles,  scarlet  fever,  typhus  fever,  infantile  paralysis,  small- 
pox^ chickenpox,  relapsing  fever,  dengue,  and  even  tuberculosis  in  large 
part.  It  is  quite  true  that  some  of  these  infections  may  be  communi- 
cated to  the  lower  animals  under  experimental  conditions,  but  they  do 
not,  as  a  rule,  occur  in  them  under  natural  conditions.  In  other  words, 
most  of  the  communicable  diseases  from  which  man  suffers  are  specific; 
the  degree  of  specificity  varying  slightly  with  the  different  infections. 

It  is,  therefore,  plain  that  man  is  the  great  source  and  reservoir  of 
human  infections.  Man  is  man's  greatest  foe  in  this  regard.  The  fact 
that  most  of  the  communicable  diseases  must  be  fought  in  the  light  of 
an  infection  spread  from  man  to  man  is  one  of  the  most  important 
advances  in  preventive  medicine.  This  new  thought  has  crystallized 
out  of  a  mass  of  work  in  the  sanitary  sciences  during  the  past  decade, 
especially  from  researches  upon  tuberculosis,  typhoid  fever,  cerebrospinal 
meningitis,  and  other  communicable  diseases.  Formerly  sanitarians 
regarded  the  environment  as  the  main  source  of  infection.  We  now 
know  that  water,  soil,  air,  and  food  may  be  the  vehicles  by  which  the 
viruses  of  the  communicable  diseases  are  sometimes  transferred — that  is, 
they  are  media  of  conveyance  rather  than  sources  of  infection.  Most  of 
the  microorganisms  causing  the  communicable  diseases  of  man  are  frail 
and  soon  die  in  our  environment,  as  in  the  air,  soil,  or  water.  Most  of 
them  are  obligate  pathogens  and  cannot  or  do  not  grow  or  multiply 
in  our  environment. 

From  the  lower  animals,  particularly  the  domesticated  animals,  man 
contracts  a  number  of  infections.  Thus  we  contract  rabies  and  echino- 
coccus  cysts  from  the  dog ;  plague  from  the  rat ;  glanders  from  the  horse ; 
trichinosis  from  hogs ;  anthrax  from  cattle ;  malta  fever  from  goats ;  foot- 
and-mouth  disease  from  cattle;  paratyphoid  from  the  flesh  of  cattle  and 
swine;  tuberculosis,  in  part,  from  cattle;  tapeworms  and  other  animal 
parasites  from  the  meat  of  fish,  fowl,  and  mammals.  Various  skin  para- 
sites are  also  contracted  from  the  lower  animals,  as  ringworm  from  cats, 

362 


SOME    GENERAL    CONSIDERATIONS  363 

fleas  from  clogs,  etc.  The  number  of  these  diseases  and  the  extent  of 
their  ravages  are  notably  less  than  those  contracted  from  man  himself. 

The  association  between  man  and  the  domestic  animals  is  intimate, 
and  the  contact  with  rats,  mice,  and  vermin  is  much  closer  and  more 
frequent  than  we  suspect.  While  man  contracts  several  infections  from 
such  relations,  animals  on  the  other  hand  contract  a  few  diseases  from 
man,  such  as  trichinosis,  Taenia  solium.  Taenia  saginata,  and  cowpox. 

The  knowledge  that  most  infections  are  spread  rather  directly  from 
man  to  man  brings  in  all  the  forces  of  sociology  to  that  of  preventive 
medicine.  The  task  of  preventive  medicine  is  thereby  rendered  much 
more  difficult  from  the  fact  that  most  infections  depend  upon  the  con- 
trol of  man  himself.  We  ruthlessly  wage  war  against  insects  or  against 
infected  food  or  water.  In  other  words,  we  can  arbitrarily  control  our 
environment  to  a  very  great  extent,  but  the  control  of  man  himself 
requires  the  consent  of  the  governed.  Thus  it  is  easier  to  stamp  out 
yellow  fever  than  to  control  typhoid  fever.  It  is  easier  to  suppress 
malaria  than  syphilis,  rabies  than  influenza,  trichinosis  than  measles. 
Cattle  appear  to  be  mutely  thankful  when  protected  by  inoculation 
against  blackleg  or  anthrax,  but  man  rebels  against  one  of  the  best 
of  all  specifics — vaccination  against  smallpox.  The  fact  that  man  is 
the  chief  source  and  reservoir  of  most  of  his  own  infections  adds  greatly 
to  the  scope  and  difficulties  of  public  health  work  and  often  makes  the 
prevention  of  disease  depend  upon  social  changes.  In  this  sense  pre- 
ventive medicine  is  a  very  important  factor  in  sociology. 

Modes  of  Transference. — The  viruses  of  the  communicable  diseases 
may  take  various  routes  of  transference  from  man  to  man  or  from 
animal  to  man.  These  routes  are  spoken  of  as  the  modes  of  infection, 
the  modes  of  transference,  or  sometimes  as  the  vehicles  of  infection. 
Formerly  they  were  spoken  of  as  the  "channels  of  infection,"  but  now 
we  restrict  that  term  to  the  special  channels  by  which  the  infection 
enters  the  body.  Thus  the  channel  of  infection  in  tuberculosis  may  be 
the  respiratory  tract,  the  digestive  system,  or  the  skin;  whereas  the 
mode  of  infection  is  from  tuberculous  sputum,  either  by  direct  contact 
or  through  the  air,  as  in  droplet  infection,  or  through  milk  or  some 
other  vehicle. 

The  modes  of  transference  may  be  grouped,  for  convenience,  under 
three  general  heads:  (1)  direct,  (2)  indirect,  and  (3)  through  an  in- 
termediate host.  In  the  great  majority  of  cases  the  virus  is  transferred 
more  or  less  directly  by  what  is  now  known  as  contact  infection.  In 
many  instances  the  virus  is  transferred  indirectly  through  water,  food, 
soil,  air,  etc.  In  a  large  group  of  diseases  the  transfer  is  through  an 
intermediate  host  which  furnishes  the  growing  list  of  insect-borne  dis- 
eases. 

The  transfer  is  usually  quite  direct  from  one  person  to  the  next.     The 


364  SOME    GENEIfAJ.    (JONSI  DELATIONS 

agents  of  infection,  as  a  rule,  (]o  not  travel  far.  The  danger  diminishes 
inversely  as  "the  cube  of  the  distance,"  except  wlien  favorcnl  l)y  human 
agencies  as,  for  example,  when  infection  is  transmitted  long  distances 
by  trade  and  travel,  or  spread  broadcast  in  water  or  milk  supplies. 

Contact  Infection. — "Contact  infection"  is  a  convenient  term  in- 
tended to  include  a  group  of  circumstances  in  which  infection  is  spread 
more  or  less  directly  or  indirectly  from  person  to  person.  Contact  in- 
fection assumes  a  transfer  of  quite  fresh  infective  material.  Actual 
contact  between  the  two  individuals  is  not  .necessary,  but  the  convey- 
ance is,  nevertheless,  pretty  close  in  time  and  space.  Contact  infection 
alone  may  be  responsible  for  epidemic  outbreaks,  even  in  the  case  of 
typhoid  fever. 

The  diseases  in  which  contact  infection  plays  a  dominant  role  are 
those  in  which  the  virus  leaves  the  body  in  the  discharges  from  the 
mouth  and  nose,  as  tuberculosis,  diphtheria,  scarlet  fever,  measles,  in- 
fluenza, common  colds,  cerebrospinal  meningitis,  whooping-cough, 
mumps,  etc.  Contact  infection  also  plays  a  large  role  in  diseases  in  which 
the  virus  leaves  "the  body  in  the  fecal  and  urinary  discharges,  as  in 
typhoid,  cholera,  dysentery,  and  other  intestinal  infections. 

In  contact  infection  the  virus  may  be  transferred  from  man  to  man 
directly  by  actual  contact,  as  in  hissing,  or  more  indirectly  upon  soiled 
hands,  contaminated  towels,  or  infected  cups,  spoons,  toys,  remnants 
of  food,  and  other  objects  which  have  recently  been  mouthed  or  handled 
by  the  infected  person.  Droplet  infection  is  also  included  under  the 
convenient  term  "contact."  As  a  matter  of  fact,  the  ways  by  which  the 
infection  may  be  transferred,  and  still  be  considered  contact  infection, 
are  numerous  and  varied.  In  every  instance,  however,  the  transfer  is 
brought  about  in  pretty  close  association  with  the  infected  person. 

Indirect  Infection. — A  large  group  of  diseases  are  conveyed  in- 
directly from  person  to  person  through  the  water,  food,  soil,  and  occa- 
sionally through  the  air.  Diseases  may  be  conveyed  great  distances 
by  means  of  food  or  water;  they  are  never  conveyed  long  distances 
through  the  air.  In  the  large  majority  of  the  diseases  contracted  by 
indirect  infection  the  virus  is  taken  into  the  system  through  the  mouth 
and  discharged  from  the  body  in  the  feces.  The  best  examples  of  this 
class  are  typhoid  fever,  cholera,  and  dysentery.  The  relation  of  soil, 
food,  water,  air,  and  our  environment  is  discussed  separately. 

The  insect-borne  diseases  form  a  large  and  important  group,  which 
are  fully  discussed  in  Chapter  IV,  page  201. 

Carriers,.- — By  the  term  "carrier"  we  understand  a  person  who  is 
harboring  a  pathogenic  microorganism,  but  who,  nevertheless,  shows  no 
signs  or  symptoms  of  the  disease.  Thus  a  person  may  have  diphtheria 
bacilli  in  the  nose  and  throat,  but,  nevertheless,  be  in  good  health. 
The  same  is  true  with  the  pneumococcus,  the  meningococcus,  strepto- 


SOME    GENERAL    CONSIDERATIONS  365 

eoeciis,  and  many  other  microorganisms.  Persons  inay  have  typhoid 
bacilli,  cholera  vibrio,  or  hookvi^orms  in  their  intestinal  tract  without 
showing  manifestations  of  these  parasites.  Furthermore,  persons  may 
have  Plasmodia  in  their  blood  or  spleen  without  having  clinical  malaria, 
and  so  on  through  a  long  list  of  infections. 

Persons  who  harbor  pathogenic  bacteria  without  showing  symptoms 
are  known  as  "bacillus  carriers,"  those  who  harbor  protozoa  are  known 
as  "protozoon  carriers,"  etc.  Carriers  may  be  acute,  chronic,  or  "tem- 
porary"— that  is,  a  person  who  discharges  pathogenic  microorganisms 
a  few  weeks  after  convalescence  is  known  as  an  "acute  carrier,"  one  who 
continues  to  harbor  the  microorganisms  for  months  and  years  is  knoAvn 
as  a  "chronic  carrier."  A  "temporary  carrier"  is  a  person  in  good  health 
who  has  never  had  the  infection,  but  who  harbors  and  discharges  a 
pathogenic  microorganism  for  a  brief  space  of  time. 

The  demonstration  that  many  persons  are  carriers  of  infection  has 
thrown  a  new  light  upon  the  control  of  the  communicable  diseases. 
With  the  new  facts  has  come  a  realization  of  added  difficulties.  Carriers 
can  only  be  detected  by  painstaking  laboratory  examinations.  When 
discovered  their  control  is  as  difficult  as  it  is  important.  We  cannot 
lightly  imprison  persons  in  good  health,  even  though  they  are  a  menace 
to  others,  especially  in  the  case  of  breadwinners.  In  some  infections 
there  are  so  many  carriers  that  it  would  require  military  rule  to  carry 
out  such  a  plan.  Fortunately  in  most  cases  absolute  quarantine  is  not 
necessary.  Sanitary  isolation  is  sufficient.  Thus  the  danger  from  a 
typhoid  carrier  may  be  neutralized  if  the  person  exercises  scrupulous 
and  intelligent  cleanliness,  and  is  not  allowed  to  handle  food  intended 
for  others.  Such  a  person  might  well  be  engaged  as  carpenter,  seam- 
stress, or  other  occupation  without  endangering  his  fellowmen. 

The  fact  that  carriers  exist  in  a  large  number  of  diseases  makes 
their  suppression  one  of  great  practical  difficulty.  The  cure  of  carriers 
is  one  of  the  pressing  problems  in  preventive  medicine.  One  hopeful 
feature  of  the  carrier  situation  is  that  their  number  may  be  diminished 
by  isolating  and  diminishing  the  cases  of  the  corresponding  disease. 
Thus,  the  number  of  typhoid  carriers  falls  oif  sharply  as  a  result  of  any 
successful  measure  directed  only  against  the  clinical  case.  The  facts  con- 
cerning carriers  have  been  discussed  separately  under  each  disease  in 
which  they  occur. 

Missed  Cases. — By  missed  cases  we  understand  mild  and  atypical 
instances  of  disease  which  are  not  recognized  clinically.  Almost  all 
diseases  vary  greatly  in  severity.  Thus  we  have  walking  typhoid  and 
ambulant  plague.  Measles,  scarlet  fever,  yellow  fever,  influenza,  and 
most  other  infections  may  be  so  mild  that  they  escape  notice.  Even  the 
patient  himself  may  not  know  he  is  sick.  These  mild  cases  go  to  school, 
ride  in   street   ears,  attend   theaters,  continue  at  their  usual  work  in 


366  SOME    GENERAL    CONSIDERATIONS 

crowded  factories  and  other  places,  handle  our  food,  and  thus  spread 
infection.  It  is  now  well  known  that  missed  cases  are  a  prolific  source 
of  spreading  the  infection  of  many  of  the  communicable  diseases;  they 
form  an  important  factor  in  preventive  medicine. 

Channels  of  Infection. — There  are  numerous  channels  by  which 
infection  may  enter  the  body.  These  are  usually  grouped  under  three 
headings:  (1)  the  respiratory  tract,  (2)  the  digestive  tract,  and  (3) 
through  the  skin.  Perhaps  90  per  cent,  of  all  infections  are  taken  into 
the  body  through  the  mouth.  They  reach  the  mouth  in  water,  food, 
fingers,  dust,  and  upon  the  innumerable  objects  that  are  sometimes 
placed  in  the  mouth.  The  fact  that  the  great  majority  of  infections 
are  taken  by  way  of  the  mouth  gives  scientific  direction  to  personal 
hygiene.  Sanitary  habits  demand  that  the  hands  should  be  washed  after 
defecation  and  again  before  eating,  and  fingers  should  be  kept  away 
from  the  mouth  and  nose,  and  that  no  unnecessary  objects  should 
be  mouthed.  All  food  and  drink  should  be  clean  or  thoroughly 
cooked.  These  simple  precautions  alone  would  prevent  many  a  case  of 
infection. 

"Contagious"  and  "Infectious." — These  are  popular  terms  which 
lack  scientific  precision.  The  words  have  been  used  in  very  diverse 
senses. 

A  contagious  (contingere,  to  touch)  disease  is  one  that  is  readily 
communicable— in  common  parlance,  "catching."  Formerly  a  contagious 
disease  was  considered  as  one  which  is  caught  from  another  by  contact, 
by  the  breath,  or  by  effluvia.  A  contagious  disease  implies  direct  or 
personal  contact.  If  contagious  diseases  are  limited  to  those  contracted 
by  direct  contact  or  touch,  as  the  etymology  of  the  word  signifies,  only 
syphilis  and  diseases  similarly  contracted  would  be  contagious.  As  a 
matter  of  fact,  smallpox  and  measles  are  types  of  contagious  diseases,  as 
the  term  is  now  usually  understood. 

An  infectious  (inficere,  to  put  in,  dip  in,  or  mix  in)  disease  is  usually 
considered  as  one  not  conveyed  directly  and  obviously,  as  in  the  case  of 
contagion,  but  indirectly  through  some  hidden  influence  or  medium.  In 
the  days  when  specific  febrile  diseases  were  regarded  as  caused  by  mias- 
mata and  noxious  effluvia,  the  terms  "infectious"  and  "miasmatic"  dis- 
eases were  more  or  less  synonymous.  Typhoid  fever  was  often  taken  as 
a  type  of  an  infectious  disease.  Malaria  was  the  type  of  a  miasmatic 
disease. 

These  distinctions  are  entirely  artificial,  and  serve  no  useful  pur- 
pose. Most  of  the  communicable  diseases  may  be  transmitted  from  the 
sick  to  the  sound  in  several  ways.  Infectious  diseases  may  be  contagious, 
and  contagious  diseases  are  infectious.  Dividing  diseases  into  those 
which  are  contagious  and  those  w^hich  are  infectious  entirely  leaves  out 
of  consideration  the  important  class  of  insect-borne  diseases.     The  terms 


SOME    GENEKAL    CONSIDEKATIONS  367 

contagious  and  infectious  have  always  lacked  scientific  precision  and 
have  been  the  source  of  some  confusion.  The  word  "communicable" 
is  a  much  better  term  and  should  be  given  preference. 

A  communicable  disease  is  one  caused  by  a  specific  virus  transferred 
in  a  great  variety  of  ways.  The  term  "communicable"  ignores  the  mode 
of  transference.  There  is  a  great  difference  in  the  degree  of  communi- 
cability ;  some  diseases  are  readily  communicable,  others  transmitted  with 
difficulty.  The  evidences  of  comm  unicability  are  not  so  obvious  in  chronic 
infections,  such  as  tuberculosis,  or  in  diseases  with  a  long  period  of  in- 
cubation, such  as  typhoid  fever.  The  relationship  between  one  case  and 
the  next  is  often  far  removed  in  time  and  space.  If  tuberculosis  were  an 
acute  infection  like  diphtheria  it  would  be  regarded  popularly  as  being 
just  as  contagious  as  that  disease. 

Epidemic,  Endemic,  Pandemic,  and  Prosodemic. — A  disease  is  said 
to  be  epidemic  (epi  =  on,  upon,  and  demos  =  people)  when  it  is  common 
to  or  affecting  at  the  same  time  a  large  number  of  persons  in  a  commu- 
nity in  a  short  time.  A  disease  which  spreads  rapidly  and  attacks  many 
people  at  the  same  time  is  usually  said  to  be  epidemic. 

A  disease  is  said  to  be  endemic  (en:=m,  tiemos  =  people)  when  it 
is  peculiar  to  a  district  or  particular  locality,  or  limited  to  a  class  of 
persons.  An  endemic  disease  is  one  which  is  constantly  present  to  a 
greater  or  less  degree  in  any  place,  as  distinguished  from  an  epidemic 
disease,  which  prevails  widely  at  some  one  time  or  periodically.  A 
sporadic  (occurring  singly)  disease  is  one  in  which  a  few  scattering 
cases  occur  now  and  then. 

Endemic  diseases  are  apt  to  flare  up  and  become  epidemic.  Insect- 
borne  diseases  are  the  best  examples  of  endemicity,  as  their  prevalence 
is  strictly  limited  by  the  geographic  distribution  of  the  intermediate 
host.  Yellow  fever  has  long  been  endemic  in  Havana,  cholera  in  India, 
typhoid  fever  in  Washington,  and  plague  in  Tibet. 

These  terms  not  only  lack  precision,  but  are  variously  conceived  and 
differently  defined.  Thus  typhoid  fever  is  said  to  prevail  in  Boston, 
but  a  similar  number  of  cases  in  Germany  would  be  regarded  as  an 
epidemic.  For  the  purposes  of  maritime  quarantine  a  disease  is  con- 
sidered epidemic  if  there  is  more  than  one  focus  of  infection;  that  is, 
if  several  cases  occur  which  have  no  apparent  connection  with  each 
other.  Strictly,  therefore,  according  to  this  definition,  two  cases  may 
constitute  an  official  epidemic  and  the  port  would,  therefore,  be  regarded 
as  infected. 

It  is  not  feasible  to  state  just  how  many  cases  of  a  disease  constitute 
an  epidemic.  Ordinarily  a  few  cases  of  a  communicable  disease  in  a 
village  or  small  town  is  not  regarded  as  an  epidemic;  however,  five 
cases  of  typhoid  fever  in  Podunk  (population  1,000)  is  the  equivalent 
of  5,000  cases  in  a  city  of  1,000,000.     By  the  same  token,  one  or  two 


368  SOME    GENEllAL    COxNyiDEKATIONS 

.cases  in  a  small  village  would  proportionately  constitute  an  epidemic 
of  unknown  magnitude  in  a  metropolis. 

''Pandemic"  {pan  =  all,  demos  =  people)  is  a  term  used  to  desc-ribe 
a  disease  which  is  more  or  less  epidemic  everywhere.  Pandemics  affect 
a  large  number  of  people  in  a  large  number  of  countries  at  t)ie  same  time. 
Thus  there  have  been  four  great  pandemics  of  plague,  when  it  spread 
to  the  four  quarters  of  the  globe.  In  1889-90  influenza  was  pandemic. 
It  is  not  usual,  although  quite  proper,  to  regard  tuberculosis,  syphilis 
and  typhoid  fever  as  pandemic. 

Sedgwick  proposes  the  term  "prosodemic"  (proso  =^  through,  demos 
:=  people)  to  take  the  place  of  the  unsatisfactory  word  "endemic."  Proso- 
demic  suggests  the  prevalence  of  a  disease  which  is  being  communicated 
from  person  to  person  through  the  community  by  various  means,  but 
especially  by  contact. 

Fomites  (from  fomes,  touch- wood  or  tinder)  is  defined  as  any  sub- 
stance capable  of  absorbing,  retaining,  or  transporting  infectious  germs. 
Fomites  usually  refers  to  inanimate  things,  such  as  bedding,  clothing, 
etc.  The  term  was  especially  used  in  connection  with  yellow  fever,  in 
which  the  greatest  variety  of  objects,  such  as  a  lock  of  hair,  the  false 
bottom  of  a  trunk,  cofl^ee  sacks,  a  mattress,  and  letters  were  said  to  be 
the  fomites  which  touched  off  an  epidemic.  Woolen  clothing  or  the 
doctor's  beard  are  popular  and  supposedly  dangerous  examples  of  fomites. 

The  importance  of  inanimate  objects  as  vectors  of  pathogenic  micro- 
organisms is  assuming  a  minor  role  in  the  minds  of  most  sanitarians. 
Thus  we  no  longer  think  of  such  objects  as  books,  umbrellas,  floors,  walls, 
curtains,  and  furniture  as  likely  to  transmit  the  virus  of  disease.  We 
know  that  most  of  the  pathogenic  bacteria  soon  die  when  exposed  to 
dryness  and  adverse  conditions  upon  exposed  surfaces.  We  now  concen- 
trate our  efforts  more  upon  handkerchiefs,  towels,  bed  and  body  linen, 
drinking  cups,  remnants  of  food,  toys,  pencils,  table-ware,  and  other 
objects  that  have  recently  been  mouthed  by  the  infected  individual.  Such 
fomites  may  readily  transfer  fresh,  live  and  virulent  virus  from  one  per- 
son to  the  next. 

The  Management  of  an  Epidemic  Campaign. — The  first  essential 
for  success  in  the  suppression  of  an  epidemic  is  a  knowledge  of  the 
epidemiology  of  the  disease.  The  most  important  single  information 
from  a  practical  standpoint  is  a  knowledge  of  the  mode  of  transference 
of  the  infection.  We  do  not  know  the  cause  of  yellow  fever;  however, 
yellow  fever  campaigns  have  been  crowned  with  success  because  we  know 
it  is  transmitted  through  the  bite  of  a  mosquito.  We  know  the  cause 
of  cerebrospinal  meningitis,  but  there  is  still  uncertainty  concerning 
its  usual  mode  of  transmission,  and,  therefore,  our  efforts  against  this 
disease  have  been  unavailing".  The  fact  that  we  know  that  hookworm 
disease  is  transmitted  by  the  larvae  through  the  skin  is  of  vital  impor- 


SOME    GENERAL    CONSIDERATIONS  3G9 

tance  for  the  control  of  this  disease.  Without  this  knowledge  at  least 
90  per  cent,  of  our  efforts  to  repress  hookworm  disease  would  be  wasted. 
When  typhoid  fever  was  regarded  as  chiefly  a  water-borne  infection  only 
partial  success  was  achieved,  because  contacts,  milk,  flies,  and  other  modes 
of  transference  of  the  typhoid  bacillus  were  disregarded. 

In  case  the  disease  has  an  intermediate  host  or  the  virus  is  trans- 
ferred by  an  insect  or  other  animal,  a  knowledge  of  the  biology  of  the 
animal  in  question  is  of  prime  importance.  For  example,  the  habits 
and  habitat  of  the  yellow  fever  mosquito  are  quite  different  from  those 
of  the  malarial  mosquito.  A  campaign  against  the  rat  and  flea  without 
an  acquaintance  with  their  breeding  and  feeding  places  and  the  best 
means  available  to  repress  or  suppress  such  vermin  would  be  unsuc- 
cessful. The  same  is  true  in  our  campaign  against  tuberculosis  with 
reference  to  cattle  and  man;  in  rabies  with  reference  to  dogs  and  other 
mammals ;  in  sleeping  sickness  with  reference  to  the  tsetse  fly ;  in  Texas 
fever  with  reference  to  the  tick ;  malta  fever  with  reference  to  the  goat ; 
relapsing  fever  to  the  bedbug,  and  typhus  fever  with  reference  to  the 
louse. 

AuTHOKiTY. — Proper  authority  is  necessary  in  order  to  enforce  the 
necessary  measures.  This  authority  may  come  from  the  municipality, 
the  state,  or  the  federal  government.  In  localized  outbreaks,  municipal 
authority  is  sometimes  sufficient.  More  frequently  the  wider  authority 
of  the  state  is  desirable.  In  our  country  it  is  a  recognized  principle  in 
law  that  health  laws  and  regulations  belong  to  the  police  powers  of  the 
individual  states.  In  most  instances  the  general  authority  of  the  gov- 
ernment must  be  had,  especially  as  interstate  problems  are  almost  al- 
ways involved  in  all  epidemic  outbreaks.  The  federal  authority  is  lim- 
ited in  health  matters  by  the  constitution.  It  therefore  cannot  act  within 
a  state  unless  invited  to  do  so  by  the  duly  constituted  authorities  of  the 
state.  To  send  government  health  officers  into  a  state  against  the  will  of 
the  state  corresponds  to  the  sending  of  the  regular  army  into  a  state 
to  enforce  measures  against  the  will  of  the  governor  of  that  state.  Such 
extreme  measures  are,  therefore,  only  taken  in  times  of  emergency. 
Occasionally  a  state,  refusing  to  take  necessary  action  and  protect  the 
other  states,  is  quarantined.  Thus,  when  California  refused  to  officially 
recognize  the  existence  of  plague  in  1899,  the  government  quarantined 
the  entire  state.  On  account  of  our  dual  form  of  government  it  is 
important  that  the^federal  government,  the  state,  and  the  local  authorities 
cooperate  in  a  friendly  spirit.  Epidemic  diseases  recognize  no  geo- 
graphical boundary,  and  energetic  and  cooperative  action  is  usually  called 
for  to  suppress  an  outbreak. 

It  is  the  common  experience  of  those  who  have  to  deal  with  epi- 
demics that  there  is  usually  insufficient  authority  in  law  to  provide  for 
an  emergency.     It  is,  therefore,  often  necessary  to  take  the  bit  in  the 


370  SOME    GENERAL    CONSIDERATIONS 

teeth  and  adopt  arbitrary  measures  wliicJi  usually  have  the  support  of 
the  l)etter  element  in  the  community.  Advanta^'c  may  he  taken  of  an 
epidemic  to  obtain  laws  to  imjn-ove  the  healtii  organization  or  the  powers 
of  the  healtli  officer.  In  this  way  an  epidemic  serves  a  useful  purpose 
in  arousing  action. 

In  the  conduct  of  an  epidemic  it  is  very  important  that  all  the 
authority  should  center  in  one  i^erson.  To  conduct  an  epidemic  with  a 
board  of  health  or  a  health  committee  or  a  commission  of  any  kind  in- 
vites failure.  It  would  be  just  as  foolish  to  have  a  board  of  generals  to 
fight  a  battle.  Those  who  have  been  through  many  epidemics  realize 
that  it  is  no  figiire  of  speech  to  compare  an  epidemic  campaign  to  a 
battle.  It  is  a  fight  carried  on  at  high  tension,  and,  although  the  foe 
is  invisible,  it  is  a  battle  in  every  sense  of  the  word. 

Ways  and  Means.- — It  is  impossible  to  carry  on  a  successful  cam- 
paign against  an  epidemic  without  material  resources.  An  epidemic 
campaign  is  expensive  and  success  depends  upon  generous  support.  In 
most  of  the  campaigns  against  yellow  fever,  plague,  and  cholera  that 
have  been  waged  in  this  country  the  expense  has  been  borne  in  part  by 
the  government,  in  part  by  the  municipality  or  state,  and  in  part  by 
subscriptions  from  citizens.  The  government  has  an  epidemic  fund 
appropriated  by  Congress  and  which  is  usually  kept  at  about  a  million 
dollars.    This  fund  is  available  only  for  plague,  yellow  fever,  and  cholera. 

Okganizatiox. — Headquarters  should  be  organized  at  a  convenient 
part  of  the  city  or  the  infected  area,  and  headquarters  should  have  all 
the  modern  office  equipment  and  transportation  facilities  necessary  for 
the  quick  dispatch  of  business.  The  city  is  then  divided  into  sanitary 
districts.  These  may  correspond  to  the  political  wards  or  the  police 
districts  and  a  subordinate  is  placed  in  charge  of  the  work  in  each  district. 
These  districts  are  known  as  divisions,  and  the  officer  in  charge  of  each 
division  must  establish  headquarters  for  the  work  of  that  division.  The 
actual  work  is  done  from  division  headquarters,  under  the  direction  of 
the  chief  in  charge  of  the  epidemic. 

It  is  also  necessary  to  establish  a  laboratory  in  case  laboratory  diag- 
nosis is  necessary  for  the  recognition  of  cases  or  carriers,  and  emergency 
hospitals  and  detention  barracks  must  be  provided.  Few  cities  have  suf- 
ficient hospital  facilities  to  meet  a  sudden  emergency.  Temporary  ar- 
rangements must  therefore  be  made.  A  modern  school  building  makes 
a  very  good  hospital  and  may  be  equipped  for  the  reception  of  patients 
at  short  notice.  Various  squads  must  now  be  organized  to  carry  on 
the  particular  work  at  hand.  In  the  case  of  yellow  fever  these  will  be 
mosquito  brigades;  in  the  case  of  plague,  rat  brigades  and  disinfectors, 
and  in  the  case  of  smallpox,  vaccinators,  etc. 

It  is  frequently  desirable,  in  fact  often  necessary,  to  make  a  house 
to  house  ins]iection  tliroughout  the  infected  district  in  order  to  collect 


QUAEAXTINE  371 

certain  data,  to  determine  whether  cases  are  being  reported  or  hidden, 
and  to  carry  out  special  measures.  Tliese  house  to  house  canvasses  are 
under  the  immediate  direction  of  the  officer  in  charge  of  the  sanitary 
district  and  should  be  repeated  as  often  as  the  occasion  may  demand. 

It  is  essential  that  all  cases  or  suspected  cases  of  the  disease  be 
promptly  reported,  for  a  case  of  communicable  disease  known  is  a  case 
neutralized.  It  is  the  missed  cases  and  the  hidden  cases  that  are  par- 
ticularly dangerous. 

Education. — A  campaign  of  education  should  be  carried  on  at  the 
same  time  that  the  disease  is  being  attacked.  The  people  are  keenly 
alive  and  hungry  for  information.  Well-worded  articles  in  the  news- 
papers, circulars,  pamphlets,  lectures,  demonstrations,  and  the  other 
usual  methods  are  available.  The  education  of  the  community  is  im- 
portant in  order  to  obtain  cooperation,  for  it  is  a  handicap  to  fight  an 
epidemic  without  the  active  support  of  the  people.  While  the  first  duty 
of  the  officer  in  charge  is  to  allay  panic  and  calm  the  unreasonable  fears 
of  the  stricken  community,  the  opposite  extreme  must  be  avoided.  A 
healthy  fear  of  the  disease  is  one  of  the  best  instruments  in  the  armamen- 
tarium of  the  sanitarian.  It  is  almost  hopeless  to  make  progress  against 
disease  where  the  people  supinely  accept  the  conditions.  Thus,  if  the 
people  of  the  United  States  feared  typhoid  fever  as  they  do  yellow  fever, 
it  would  soon  diminish  to  the  vanishing  point. 


QUARANTINE 

The  word  "quarantine"  is  derived  from  the  Italian  word  '"quarante,-" 
meaning  forty.  Its  present-day  meaning  dates  from  the  middle  ages 
when  Venice  and  other  Hanseatic  cities  detained  arriving  ships  with 
cases  of  pestilence  aboard  for  a  period  of  forty  days.  This  was  the  first 
systematic  application  of  maritime  quarantine,  although  from  the  earliest 
times  lepers  were  segregated  or  quarantined.  To-day  we  have  many  kinds 
of  quarantine :  maritime  quarantine,  interstate  quarantine,  house  quaran- 
tine, cattle  quarantine,  yellow  fever  quarantine,  shotgun  quarantine,  etc. 

The  dominating  principle  in  modern  quarantine  is  that  it  must  be 
a  sieve  or  filter  and  not  a  dam.  All  quarantines  based  upon  the  prin- 
ciple of  the  Chinese  wall  are  doomed  to  fail.  The  object  of  quaran- 
tine is,  then,  to  destroy,  detain,  or  isolate  infection  with  the  least  pos- 
sible hindrance  to  trade  and  travel.  The  art  consists  in  regulating  the 
openings  in  the  quarantine  sieve  so  as  to  hold  back  certain  infections, 
but  permit  all  else  to  pass.  Maritime  quarantine  may  be  regarded  as 
a  coast  defense  against  exotic  pestilence,  a  defense  which  guards  against 
an  invisible  foe  ofttimes  more  damaging  than  hostile  armies  and  navies. 
The  cure  for  quarantine  is  sanitation. 


373  SOME    GENERAL    CONSIDERATIONS 

If  all  communities,  especially  seaports,  were  to  place  their  cities  in 
the  best  sanitary  condition  in  accordance  with  the  teachings  of  modern 
science,  there  would  be  little  danger  of  disease  spreading  to  epidemic 
proportions  and  very  little  need  of  maritime  quarantine.  If  the  ports 
in  our  southern  littoral  would  free  themselves  of  the  Stegomyia  mosquito 
they  could  laugh  at  yellow  fever.  A  city  containing  few  rats  could  no, 
have  an  epidemic  of  plague.  A  port  supplied  with  a  pure,  well-protected 
water  supply  need  not  fear  a  water-borne  epidemic  or  cholera.  A  thor- 
oughly vaccinated  community  runs  no  hazard  from  smallpox.  Typhus 
fever  could  not  spread  in  a  community  with  cleanly  personal  habits,  that 
is,  one  free  from  lice  and  other  vermin. 

Maritime  Quarantine. — Maritime  quarantine  in  this  country  is 
enforced  only  against  six  diseases,  viz.,  cholera,  yellow  fever,  plague, 
typhus  fever,  smallpox,  and  leprosy.  We  do  not  quarantine  against 
typhoid  fever,  tuberculosis,  measles,  and  other  infections  which  are  not 
greatly  feared  and  which  are  constantly  with  us.  Infections  of  a  non- 
quarantinable  nature,  such  as  scarlet  fever,  measles,  etc.,  arriving  at  a 
port  are  permitted  to  enter,  but  must  then  comply  with  the  local  laws 
and  regulations. 

The  period  of  detention  is  based  upon  the  usual  period  of  incubation 
for  each  disease  and  is  as  follows : 

Cholera 5    days. 

Yellow  fever 5,  sometimes  6  days. 

Plague 7    days. 

Typhus  fever 12    days. 

Smallpox    14    days. 

Leprosy not    admitted. 

Tlie  time  of  detention  is  usually  counted  from  the  completion  of 
disinfection  or  at  least  from  the  last  possible  exposure  to  the  infection. 
This  is  usually  not  a  very  difficult  matter  for  the  quarantine  officer  to 
decide,  but  in  case  of  doubt  the  public  is  given  the  benefit. 

No  communication  is  permitted  with  a  vessel  in  quarantine  except- 
ing under  supervision  of  the  quarantine  officer;  that  is,  no  one  is  allowed 
to  board  the  vessel  or  leave  it,  and  nothing  is  allowed  to  be  thrown  over- 
))oard,  taken  ashore,  or  brought  on  board  without  the  express  permission 
of  the  quarantine  officer.  These  restrictions  apply  alike  to  foods  and  to 
merchandise  of  all  kinds. 

The  vessel  itself  may  be  disinfected  and  furnished  with  a  fresh  crew 
and  released  from  quarantine  while  the  passengers  and  crew  are  detained 
in  suitable  barracks.  Vessels  trading  with  infected  ports  should  carry 
immune  crews;  that  is,  persons  who  have  either  had  the  disease  or  have 
been  rendered  actively  immune  through  one  of  the  vaccines  or  viruses. 

When  a  quarantinable  disease  breaks  out  on  board  a  vessel  it  is  of 
practical  importance  for  the  quarantine  officer  to  determine  whether  the 


QUAEANTINE  373 

iiirection  was  contracted  on  board  the  vessel  or  ou  land.  Jn  the  tirst  case 
the  vessel  must  be  regarded  as  infected  and  the  measures  used  for  its 
purification  are  much  more  exacting  than  in  the  second  case.  Thus,  if 
plague  breaks  out  within  five  days  from  the  time  a  vessel  leaves  an  in- 
fected port,  and  no  other  case  occurs,  it  is  exceedingly  probable  that  the 
patient  contracted  his  disease  ashore  and  was  in  the  period  of  incubation 
when  he  came  on  board.  If,  however,  plague  breaks  out  after  five  days, 
and  especially  if  secondary  cases  occur,  it  is  evident  that  the  ship  itself 
is  infected.  The  same  reasoning  applies  to  yellow  fever  and  the  other 
communicable  diseases. 

The  measures  taken  at  quarantine  to  keep  out  these  diseases  depend 
upon  an  accurate  knowledge  of  their  cause  and  mode  of  transmission. 
Briefly  summarized,  the  measures  applicable  in  each  case  are  as  follows : 

Cholera. — Cases  are  removed  from  the  vessel  and  isolated  and  that 
part  of  the  vessel  and  the  objects  exposed  are  disinfected — formaldehyd 
for  cabins,  sulphur  dioxid  for  the  hold,  bichlorid  solution  for  surfaces, 
steam  for  fabrics  and  clothing.  A  search  is  made  for  bacillus  carriers  and 
a  bacteriological  examination  is  made  of  all  cases  of  diarrhea.  Special 
attention  is  given  to  the  water  supply,  food,  and  flies.  After  the  sick 
are  isolated  the  remainder  are  segregated  in  small  groups.  Those  espe- 
cially exposed  are  first  bathed  and  their  body  clothing  disinfected  before 
they  are  sent  to  the  detention  barracks.  In  case  of  cholera,  arrangements 
should  be  perfected  for  the  disinfection  of  the  dejecta.  Baggage  which 
has  been  exposed  is  disinfected  by  an  appropriate  method,  but  as  there  is 
little  danger  in  the  cargo,  especially  if  it  consist  of  new  manufactured 
merchandise,  this  may  be  passed  without  special  treatment. 

If  a  vessel  has  taken  water  ballast  at  an  infected  port  it  is  required 
to  empty  the  same  at  sea  and  replace  the  presumably  infected  water 
with  sea  water.  If  this  has  been  neglected  the  vessel  must  return  to 
sea  past  the  three-mile  limit  for  this  purpose.  The  water  and  the  water 
tanks  may  be  rendered  safe  by  the  use  of  chlorinated  lime. 

The  period  of  detention  in  the  case  of  cholera  is  five  days. 

Smallpox. — Ordinarily  those  who  have  had  smallpox  or  who  have 
had  a  recent  successful  vaccination  are  not  detained.  All  others  must 
submit  to  vaccination.  Persons  declining  vaccination  are  detained  for 
the  full  period  of  14  days  before  they  are  released.  As  a  rule,  it  is  not 
necessary  to  detain  cabin  passengers  because  there  is  smallpox  in  the 
steerage,  or  to  detain  the  firemen  because  there  is  smallpox  among 
the  stewards.  Vessels  arriving  with  smallpox  on  board  on  which  the  cases 
have  been  properly  isolated,  personnel  vaccinated,  and  other  sufficient 
precautions  taken  to  prevent  the  spread  of  the  disease,  need  not  be  quar- 
antined further  than  the  removal  of  the  sick,  the  disinfection  of  com- 
partments, baggage,  and  objects  that  have  been  exposed  to  the  liability  of 
infection. 


374  SOME    GENERAL    CONSIDERATIONS 

Plague. — Passengers  and  crew  from  plague-infected  ports  are  care- 
fully inspected  at  quarantine.  I'he  temperature  of  each  person  should 
be  taken  and  it  is  desirable  to  make  special  examinations  for  bubos. 
A  careful  search  is  made  for  cases  of  Festis  minor,  and  the  pneumonic 
form  of  the  disease  must  also  be  kept  in  mind.  The  period  of  detention 
in  the  case  of  plague  is  7  days.  The  sick  are  isolated  in  the  hospital 
and  the  remainder  segregated  in  small  groups.  All  persons  exposed 
to  the  infection  are  bathed  and  their  body  clothing  disinfected. 

Rats  and  fleas  on  the  vessel  must  be  killed  and  burned. 

The  destruction  of  rats  on  a  ship  requires  special  knowledge  and 
care  else  many  rats  escape.  Sulphur  fumes  generated  by  the  pot  method 
remains  the  cheapest,  simplest,  and  best  method  yet  proposed  for  this 
purpose.  Hydrocyanic  acid  is  too  dangerous,  and  funnel  gases  require 
expensive  apparatus,  and  furthermore  are  practical  only  in  large  spaces, 
such  as  the  holds  of  vessels. 

A  survey  of  the  ship  from  stem  to  stern,  from  pilot  house  to  bilge, 
should  be  made  in  order  that  the  disinfector  may  know  its  peculiarities 
of  construction,  the  location  of  apartments,  the  condition  of  doors,  ports 
and  ventilators.  Before  the  sulphur  pots  are  lighted  dunnage  must  be 
piled  up  or  slung  two  feet  from  the  floor.  Dunnage  is  a  mass  of  loose 
material,  mostly  wood,  laid  on  the  bottom  of  the  hold  for  the  cargo  to 
rest  upon  to  prevent  injury  from  water.  It  is  also  used  to  stow  among 
casks  and  packages  to  prevent  their  motion  at  sea.  All  limber  boards  over 
bilges  and  movable  sheathing  on  sides  should  be  taken  up.  Air  streaks 
may  be  closed,  or  better,  freely  opened  up  so  that  the  gas  may  enter  the 
large  space  between  the  inner  and  outer  sheathing  of  the  vessel.  Pipe 
casings  should  either  be  opened  or  closed  tight.  Rock  ballast  may  be 
flooded  for  the  purpose  of  drowning  rats  hiding  there. 

The  engine  room  sometimes  needs  treatment  and  all  engine-room 
lockers  should  be  freely  opened.  Forecastle  lockers,  the  forepeak  with 
small  manhole  hatch,  and  its  two  or  three  lower  compartments,  usually 
stored  with  ropes  and  canvas,  are  favorite  refuges  for  rats.  The  galley, 
pantry  and  store-rooms  must  not  be  neglected,  although  in  newer  vessels 
with  steel  decks  and  bulkheads,  they  afford  poor  hiding  places.  Rats  are 
sometimes  found  in  the  dining  saloon,  social  hall,  lifeboats,  rafts,  the 
bilges,  vegetable  bins,  refrigerating  plants,  and  even  in  the  casings  over 
the  steering-gear.  All  out-of-the-way  places  must  be  carefully  scrutinized 
after  fumigation  for  live,  dead,  or  dazed  rats. 

Special  precautions  must  be  taken  to  prevent  the  escape  of  rats. 
Vessels  quarantined  on  account  of  plague  should  be  anchored  at  suffi- 
cient distances  from  shore  to  discourage  rats  swimming  to  the  land. 
If  the  vessel  ties  up  to  the  dock,  the  hawsers  must  be  guarded  with  balls 
of  tar  or  special  traps  in  order  to  stop  rats  reaching  the  shore  along  these 
lines.     Gangplanks  must  be  taken  in  before  dark,  and,  as  rats  are  noc- 


QTJARANTmE  S^S 

turnal  in  their  habits,  searchlight  will  help  to  deter  them  from  leaving 
the  ship.  Nothing  should  be  thrown  overboard,  not  even  deck  sweepings ; 
these  should  be  burned,  but  not  in  the  galley. 

A  plague-infected  ship  is  given  a  simultaneous  disinfection  with 
sulphur  and  the  cargo  is  removed  by  a  special  procedure.  After  sulphur- 
ing, the  cargo  is  removed  piece  by  piece  to  lighters,  each  article  being 
examined  as  it  swings  overboard  for  rat  nests.  This  work  goes  on  during 
the  day,  while  the  empty  cargo  spaces  are  fumigated  with  sulphur  during 
the  night  in  preparation  for  the  next  day's  unloading. 

Special  precautions  must  also  be  taken  at  foreign  plague  ports  to 
prevent  the  ingress  of  rats  and  also  to  prevent  unnecessary  human  com- 
munication with  infected  areas.  All  vessels  trading  regularly  with  plague 
ports  should  carry  an  approved  type  of  sulphur  furnace,  such  as  the 
Clayton  apparatus,  to  use  during  the  voyage,  in  order  to  kill  rats  that 
may  be  on  board.  Such  vessels  should  have  an  immune  crew;  that  is, 
persons  who  have  either  had  the  disease  or  have  been  protected  with 
Haffkine's  prophylactic. 

Yellow  Fever. — Vessels  arriving  at  an  infectible  port  from  an  in- 
fected port  are  fumigated  and  detained  five  days  as  a  precautionary 
measure  during  the  yellow  fever  season,  even  though  there  is  no  evidence 
of  sickness  on  board.  The  yellow  fever  season  usually  extends  from  May 
1  until  October  1.  The  infectible  ports  are  those  situate^  upon  the 
Atlantic  seacoast  south  of  the  Chesapeake  and  those  on  the  Gulf  of 
Mexico. 

Five  days  covers  the  period  of  incubation  of  most  cases  of  yellow 
fever  and  is  sufficient  as  a  precautionary  measure,  but  in  special  in- 
stances, as,  for  example,  if  a  case  of  yellow  fever  has  occurred  on  board 
the  vessel,  then  the  detention  is  six  days  following  fumigation.  The 
sick  are  isolated  by  the  use  of  mosquito  screens.  Patients  with  yellow 
fever  should  not  be  moved  if  this  involves  exertion  or  excitement,  which 
may  aggravate  the  disease. 

The  vessel  is  fumigated  with  an  insecticidal  substance,  preferably 
SO2,  in  order  to  kill  the  Stegomyia  calopus.  A  search  is  made  for 
breeding  places,  such  as  water  casks,  fire  buckets,  and  other  collections 
of  fresh  water  where  the  Stegomyia  larvae  and  pupae  may  develop.  The 
disinfection  of  baggage  and  fomites  is  no  longer  practiced  in  the  case  of 
yellow  fever.  Experience  has  shown  that  wooden  vessels  are  more  apt 
to  convey  yellow  fever  than  iron  vessels.  This  is  because  wooden  vessels 
carry  water  casks,  which  are  the  favorite  breeding  places  for  the  mos- 
quito, while  iron  vessels  store  their  drinking  water  in  tight  compartments 
deep  in  the  hold,  inaccessible  to  mosquitoes.  Vessels  plying  between 
infected  and  infectible  ports  should  carry  immune  crews. 

Typhus  Fever. — The  period  of  detention  for  typhus  fever  is  12  days. 
If  a  case  of  typhus  fever  occurs  upon  a  vessel  and  has  been  properly 


376  SOME    GENERAL    CONSIDERATIONS 

isolated,  and  the  vessel  is  in  good  sanitary  condition,  there  is  practi- 
cally no  danger  of  its  spread,  the  case  may  be  removed,  fumigation 
practiced  (insecticides),  and  the  vessel,  passengers,  and  crew  permitted 
to  proceed.  But,  if  the  case  has  not  been  isolated,  or  if  the  disease  has 
spread  from  one  person  to  another  upon  the  vessel,  or  if  the  ship  is 
infested  with  vermin  and  is  otherwise  in  an  unsanitary  condition,  those 
exposed  are  detained  in  quarantine  until  the  period  of  incubation  has 
elapsed.  Quarantine  procedures  in  the  case  of  typhus  fever  are  now 
focused  entirely  upon  the  louse,  which  is  the  carrier  of  the  infection. 

Leprosy. — An  alien  leper  is  not  allowed  to  land.  The  law  requires 
the  vessel  or  which  he  arrives  to  take  him  back  again.  It  is  unconstitu- 
tional to  forbid  the  landing  of  an  American  leper,  but  as  soon  as  he 
lands  he  comes  under  the  laws  of  the  city  or  state  in  which  he  finds 
himself.  Alien  lepers  are  detained  at  the  quarantine  station  and  placed 
aboard  again  when  the  vessel  is  outward  bound. 

Quarantine  Procedures. — All  vessels  arriving  at  any  port  in  the 
United  States  from  a  foreign  port  are  considered  to  be  in  quarantine 
until  they  are  given  free  practique.  The  practique  is  a  certificate  signed 
by  the  quarantine  officer  to  the  effect  that  the  vessel  and  all  on  board  are 
free  from  quarantinable  disease,  or  the  danger  of  conveying  the  same. 
In  other  words,  free  practique  is  a  permit  issued  by  the  quarantine  officer 
which  the  master  of  the  vessel  must  present  to  the  collector  of  the  port 
in  order  that  his  vessel  may  be  admitted  to  entry. 

Vessels  in  quarantine  are  required  to  fiy  a  yellow  flag  (letter  "Q" 
of  the  International  Code)  from  the  foremast.  The  quarantine  officer 
boards  the  vessel  usually  upon  the  starboard  side  and  examines  the  bill 
of  health,  the  ship  itself,  the  passengers,  the  crew,  as  well  as  the  manifests 
of  cargo,  and  sometimes  the  food  and  water  supplies,  etc.  Vessels  arriv- 
ing after  sundown  must  wait  until  sunrise  for  this  inspection;  the  time 
and  details,  however,  vary  greatly  and  depend  upon  circumstances.  Thus, 
at  the  port  of  Boston,  there  is  no  more  need  to  examine  vessels  bringing 
residents  of  London  or  Paris  than  there  would  be  to  examine  a  trainload 
of  passengers  from  New  York. 

The  detection  of  infection  on  board  a  vessel  requires  knowledge, 
tact,  and  sometimes  a  detective  instinct  on  the  part  of  the  quarantine 
officer.  Where  one  of  the  communicable  diseases  is  suspected  the  tem- 
perature of  every  person  on  board  should  be  taken.  Sometimes  special 
examinations,  as  for  bubos  in  the  case  of  plague,  are  necessary.  As  a 
rule,  all  hands  are  mustered  at  a  designated  place  on  board  the  ship 
and  then  passed  in  review,  one  by  one,  before  the  examining  physician.; 
the  number  of  persons  are  counted  and  compared  with  the  ship's  papers; 
each  person  is  critically  scrutinized  for  evidence  of  disease,  and  suspects 
are  placed  aside  for  more  careful  examination  later.  The  clinical  records 
of  the  ship's  surgeon  are  inspected  with  special  reference  to  the  diagnosis 


QUAEANTINE  377 

of  those  who  have  received  medical  care  during  the  voyage.  Tlie  manifest 
of  cargo  is  examined  for  second-hand  goods,  upholstered  furniture,  bed- 
ding, hides,  hair,  or  other  objects  that  may  require  disinfection.  Finally, 
the  ship  itself  is  inspected,  attention  being  given  especially  to  the 
forecastle,  steerage  quarters,  the  galley,  etc. 

The  Bill  of  Health.— The  United  States  Bill  of  Health  is  a  docu- 
ment issued  by  our  consul  at  the  port  of  departure  to  the  master  of 
the  vessel.  The  Bill  of  Health  contains  a  complete  description  of  the 
vessel,  the  number  of  officers,  crew,  and  passengers  (cabin  and  steer- 
age), its  sanitary  history,  and  the  sources  and  wholesomeness  of  water, 
food  supply,  etc.  Finally,  it  contains  a  statement  giving  the  number 
of  cases  and  deaths  from  yellow  fever,  cholera,  smallpox,  typhus  fever, 
plague,  and  leprosy  at  the  port  of  departure  during  the  two  weeks  pre- 
ceding the  sailing  of  the  vessel.  The  American  Bill  of  Health,  which 
is  a  formidable  document,  must  be  obtained  by  the  master  of  the  ves- 
sel in  duplicate;  one  copy  is  destined  for  the  collector  of  customs  at  the 
point  of  entry  and  the  other  for  the  quarantine  officer. 

The  Bill  of  Health  is  a  consular  document  (State  Department)  at 
the  port  of  departure,  but  becomes  a  customs'  paper  (Treasury  Depart- 
ment) at  the  port  of  entry.  Vessels  arriving  at  any  port  in  the  United 
States  or  its  dependencies  from  a  foreign  port  without  this  official  Bill 
of  Health  in  duplicate  are  subject  to  a  fine  of  $5,000.  Before  the  days 
of  telegraphy  the  Bill  of  Health  was  an  important  document  and  often 
gave  the  quarantine  officer  the  first  information  of  pestilential  disease 
abroad.  The  quarantine  officer  must  now  keep  himself  informed  not  only 
of  the  health  conditions  of  the  port  of  departure,  but  of  the  places  from 
which  the  passengers  and  crew  are  recruited. 

There  are  many  kinds  of  bills  of  health;  each  country  has  a  form 
of  its  own.  Formerly  a  bill  of  health  was  simply  a  statement  that  the 
port  of  departure  was  or  was  not  free  of  pestilential  disease ;  that  is,  the 
bill  of  health  was  either  "clean"  or  "foul."  The  American  Bill  of 
Health  gives  much  more  valuable  information  in  detail.  The  only  bill 
of  health  that  is  of  service  to  the  vessel  upon  arrival  is  the  American 
Bill  of  Health,  although  several  bills  of  health  may  be  issued  to  the 
vessel  at  the  port  of  departure.  Thus,  a  British  vessel  leaving  the  port 
of  Eio  de  Janeiro  takes  three  bills  of  health,  one  from  the  British  con- 
sul, required  by  the  British  admiralty  laws,  another  from  the  Brazilian 
authorities,  which  rs  a  clearance  paper,  and  the  third  from  the  Amer- 
ican consul,  which  is  the  only  one  of  service  upon  reaching  a  port  in 
the  United  States. 

The  Equipment  of  a  Quarantine  Station. — The  equipment  of  a 
quarantine  station  consists  of  boarding  vessels,  such  as  tugs,  launches, 
and  rowboats;  of  an  inspection  place  where  passengers,  crew,  and  sus- 
pects may  be  examincfl    (the  facilities  on  board  the  ship  are  usually 


378  SOMK.    OKjVERAL    CONSI  DI^^HA'riONS 

inadequate  I'oj-  this  piirposf!)  ;  of  disiiirecliii,!^^  apparatus  for  the  use  of 
steam,  sulphur  dioxid,  lormahlehyd,  and  inse(;ti(;ides;  shower  baths; 
detention  barracks  for  steerage,  intermediate,  aiul  eabiii  passengers,  as 
well  as  the  crew  ol"  the  vessel;  isolation  wards  in  which  cases  of  the 
quarantinable  diseases  may  be  cared  for,  and  special  wards  where  sus- 
pects or  non-contagious  cases  may  receive  treatment.  A  well-equipped 
quarantine  station  further  needs  dining-rooms  and  kitchens  for  the  vari- 
ous groups  detained ;  quarters  for  the  quarantine  officers  and  help ;  a 
wharf  and  boat  house,  and  some  provisions  for  recreation  of  those  in 
quarantine  to  dispel  the  ennui  of  the  isolation.  Finally,  a  crematory,  a 
steam  laundry,  and  special  arrangements  for  the  disposal  of  sewage  and 
garbage  are  important. 

A  laboratory  is  an  essential  feature  of  a  modern  quarantine  station. 
It  is  necessary  in  order  to  make  diagnoses  and  to  recognize  bacillus  car- 
riers, etc.  In  other  words,  a  quarantine  station,  on  account  of  its  im- 
portance and  isolation,  must  be  a  well-equipped  and  self -supporting  com- 
munity. 

Qualifications  of  the  Quarantine  Officer. — The  quarantine  officer 
must  be  a  good  diagnostician.  He  should  have  a  special  acquaint- 
ance with  the  diseases  against  which  he  stands  monitor.  Further,  he 
must  be  familiar  with  the  modes  of  spread  of  the  quarantinable  dis- 
eases and  must  know  the  value  and  limitations  of  the  germicidal  agents 
and  insecticides  he  uses.  Finally,  he  must  be  familiar  with  matters 
nautical,  and  have  an  extensive  knowledge  of  geography.  It  is  the  duty 
of  the  quarantine  officer  to  keep  posted  as  to  the  sanitary  conditions  of 
all  countries,  especially  the  towns  and  places  having  commerce  with  his 
port. 

Disinfection  of  Ships. — The  disinfection  of  a  vessel  does  not  differ 
materially  from  the  disinfection  of  houses  and  rooms.  It  should 
not,  however,  be  attempted  by  one  not  familiar  with  the  intricacies 
of  marine  architecture  and  matters  nautical,  for  many  special  condi- 
tions are  met  with  on  board  ship  that  are  very  different  from  those  found 
on  shore.  While  the  principles  of  disinfecting  as  applied  to  a  vessel 
present  nothing  unusual,  the  application  of  these  principles  calls  for 
much  ingenuity  and  the  keenest  vigilance  on  the  part  of  the  disinfector. 

It  is  important  to  enlist  the  sympathies  of  those  on  board  with  the 
necessity  of  disinfection,  for  the  successful  accomplishment  of  the  puri- 
fication of  the  vessel  may  be  materially  helped  by  the  cheerful  cooperation 
of  the  passengers  and  crew;  otherwise  the  difficulties  of  the  problem  are 
greatly  magnified. 

Formerly  a  distinction  was  made  between  the  methods  of  disinfect- 
ing a  wooden  and  an  iron  vessel.  This  arose  from  the  fact  that  almost 
all  wooden  vessels  have  some  rotten  and  spongy  wood,  especially  about 
tlie  forefoot  and  bilge.    There  are  also  many  more  cracks  and  open  joints 


QUAEANTINE  379 

about  a  wooden  ship  than  a  metal  one  which  afford  lodgment  for  organic 
matter.  In  addition  to  this,  a  wooden  hull  is  always  damper  than  an 
iron  hull,  for  almost  all  wooden  vessels  leak  more  or  less.  It  was  for- 
merly believed  that  the  microorganisms  of  disease  were  apt  to  become 
deeply  lodged  in  the  moist  dirt  and  organic  matter  of  the  many  crevices, 
but  we  now  know  that  this  is  largely  theoretical. 

A  vessel  is  rarely  so  badly  infected  that  it  needs  a  disinfection  through- 
out. Just  what  portion  of  the  vessel  and  its  contents  requires  treatment 
is  often  a  very  difficult  problem  to  solve.  There  is  no  more  reason  to 
fumigate  the  hold  of  a  vessel  because  smallpox  appeared  in  the  cabin  or 
steerage  than  there  would  be  to  disinfect  the  basement  and  subbasement 
of  a  tenement  house  because  a  case  appeared  in  one  of  the  upper  stories 
of  the  building.  When  a  communicable  disease  occurs  on  board  a  vessel 
the  infection  may  be  confined  to  one  or  two  compartments  or  to  a  limited 
area  quite  as  successfully  as  this  may  be  done  in  buildings  on  shore.  "In 
case  of  doubt,  disinfect,"  is  not  a  bad  rule  for  the  quarantine  officer 
to  follow  in  his  practical  dealings  with  ships.  For,  after  all,  the 
measures  which  must  be  taken  are  greatly  in  excess  of  the  absolute  re- 
quirements. 

Much  may  be  learned  by  a  thorough  inspection  of  the  vessel.  To  be 
sure,  we  cannot  see  the  germs  with  our  unaided  vision,  but  we  can  see 
the  dirt  and  moisture  and  other  conditions  which  favor  their  life  and 
virulence  and  can  discover  the  feeding  and  breeding  places  for  vermin. 

It  is,  therefore,  the  duty  of  the  quarantine  officer  to  require  a  very 
thorough  mechanical  cleansing  of  all  parts  of  the  ship  which,  in  his 
judgment,  require  it.  This  matter  is  dwelt  upon  because  filth  and  ver- 
min are  conditions  too  frequently  met  with  on  the  sea  and  one  of  great 
importance  to  communities  and  nations. 

While  the  general  methods  of  treating  vessels  are  the  same  for  most 
of  the  bacterial  infections,  special  methods  are  called  for  with  each  dis- 
ease. For  example,  in  cholera  particular  attention  must  be  paid  to  the 
water  and  food  supply;  for  plague  the  destruction  of  rats  and  fleas  is 
of  prime  importance ;  for  yellow  fever  attention  must  be  directed  against 
the  mosquito ;  for  smallpox  vaccination  and  the  usual  disinfection  of  the 
living  apartments,  clothing,  bedding,  and  the  like  are  required,  while  for 
typhus  fever  the  warfare  must  be  waged  against  lice. 

The  disinfection  of  a  large  vessel  cannot  effectively  be  done  with- 
out all  the  modern  contrivances  of  a  well-equipped  quarantine  station. 
A  rowboat  and  launch  or  a  small  sailing  craft  may  be  disinfected  with 
a  tub  of  bichlorid  solution,  but  good  work  cannot  be  accomplished  on 
a  large  vessel  by  the  use  of  makeshifts. 

Before  the  disinfection  of  a  vessel  is  commenced  it  should  be  brought 
alongside  the  pier  or  barge  containing  the  necessary  apparatus.  All 
the  passengers  are  then  to  be  taken  off  and  all  the  crew,  only  excepting 


380  SOME    GENET^AL    CONSTDEEATTONS 

the  few  who  are  necessary  for  the  safety  of  the  vessel  and  11ios(;  who 
are  to  help  in  the  disinfection.  The  quartermaster,  the  boatswain,  and 
the  carpenter  are  very  useful  hands  to  aid  in  tlie  process  on  account  of 
their  practical  knowledge  of  the  individual  pecidiarities  of  the  construc- 
tion of  the  vessel  and  their 'faith fuhusss  in  carryiniJ-  out  directions  with 
intelligence. 

When  the  personnel  have  left  the  vessel  all  their  effects  are  removed 
and  disinfected,  if  necessary,  in  accordance  with  the  methods  outlined 
for  objects  of  that  class.  Baggage,  bedding,  and  other  ol)jects,  no  mat- 
ter what  their  character,  after  disinfection  should  not  be  returned  on 
board  until  the  treatment  of  the  vessel  itself  is  finished.  This  injunc- 
tion applies,  of  course,  equally  well  to  persons.  In  fact,  no  one  should 
be  allowed  on  the  vessel  except  those  actually  engaged  in  the  work, 
who,  as  far  as  practicable,  should  be  immune  and  should  wear  suitable 
garments.  All  the  bedding,  bed  clothing,  hangings,  floor  runners,  and 
other  fabrics  that  have  been  exposed  to  infection  must  now  be  re- 
moved to  the  steam  chamber.  Especial  care  must  be  taken  to  obtain 
all  the  used  and  soiled  linen,  which  is  usually  kept  in  special  compart- 
ments called  the  "dirty  linen  lockers,"  which  are  usually  under  the  care 
of  one  of  the  stewards.  For  some  reason  there  is  a  dislike  to  disclose 
the  presence  of  this  soiled  wash  to  the  quarantine  officer. 

After  all  the  objects  needing  disinfection  by  special  process  have 
been  removed,  attention  is  then  directed  to  the  vessel  itself.  The  vari- 
ous compartments  of  the  vessel  may  be  disinfected  by  any  one  of  the 
methods  described  under  Eoom  Disinfection,  formaldehyd  being  the 
choice  of  the  gases  and  bichlorid  of  mercury  (1-1,000)  being  the  most 
suitable  solution  for  the  treatment  of  walls,  floors,  etc. 

The  bichlorid  solution,  which  is  sometimes  used  for  flushing  the 
forecastle,  the  steerage  compartments,  and  quarters  for  petty  officers, 
etc.,  may  be  apjDlied  with  a  force-pump  or  by  means  of  mops  and  buck- 
ets. In  applying  the  disinfection  solution  with  a  hose  begin  at  one  end 
of  the  deck  ceiling  and  systematically  flood  every  inch  of  surface,  com- 
ing down  the  walls,  and  finally  the  floor. 

In  disinfecting  large  vessels  it  is  well  to  start  forward  with  the 
forecastle  and  work  aft  systematically,  first  on  the  starboard,  then  on 
the  port  side,  taking  care  to  require  every  door  to  be  unlocked  and 
trusting  only  to  a  personal  inspection  concerning  its  contents  and  uses. 
There  are  certain  places,  such  as  the  lamp-room,  the  paint  locker,  the 
sail  locker,  the  chain  locker,  the  carpenter  shop,  and  chart  room,  the 
pilot  house,  the  engine  and  boiler  rooms,  and  the  machinery,  that  are 
rarely  infected,  and,  as  a  rule,  need  no  treatment.  Special  care,  how- 
ever, must  be  given  to  the  sick  bay  and  any  apartment  in  which  a  pa- 
tient was  cared  for,  and  all  living  apartments,  including  the  steerage. 

The  water  closets  on  board  ship  should  be  thoroughly  cleansed  and 


QUAEANTINE  381 

flushed  with  water  and  may  be  disinfected  with  chlorinated  lime  or 
carbolic  acid.  They  may  also  be  hosed  with  the  bichlorid  solution 
while  that  is  being  applied.  In  sailing  vessels  of  the  older  type  the 
forepeak  needs  similar  treatment. 

The  hold  rarely  needs  treatment  on  account  of  bacterial  infection. 
About  the  best  way  to  disinfect  the  holds  of  vessels  is  by  sulphur  fumi- 
gation or  by  a  solution  of  corrosive  sublimate  applied  with  a  hose. 
The  bilge  may  be  flushed  with  carbolic  solution  or  chlorinated  lime  and 
then  pumped  out.  When  the  hold  is  fumigated  with  siilphur,  this  may 
be  burned  in  iron  pots  set  in  pans  of  water.  The  pot  should  be  placed 
in  an  elevated  position  either  on  piles  of  ballast  or  on  the  'tween  decks. 

In  leading  sulphur  fumes  into  the  hold  from  a  sulphur  furnace  it  is 
considered  best  to  lead  the  pipes  down  the  hatch-well  toward  the  bottom 
of  the  hold,  so  that  the  apartment  may  fill  up  with  the  fumes  from  the 
bottom,  displacing  the  air  above.  For  this  reason  openings  above 
for  the  escape  of  the  air  must  be  provided.  This  is  best  managed 
by  leaving  one  or  two  of  the  ventilators  open,  or  part  of  the  hatch, 
and  after  the  gas  has  begun  to  escape  in  some  quantity  to  close  up 
tight. 

The  amount  of  sulphur  to  be  burned  may  readily  be  computed  from 
the  tonnage  of  the  vessel.  A  registered  ton  is  100  cubic  feet.  Count 
half  a  pound  for  each  ton,  which  will  make  the  necessary  five  pounds 
per  1,000  cubic  feet.  The  gross  tonnage  of  a  vessel  indicates  her  ac- 
tual cubic  capacity.  The  net  tonnage  gives  the  capacity  of  her  cargo- 
carrying  space.  The  difference  between  the  two  will  give  the  capacity 
of  the  spaces  devoted  to  the  engines,  machinery,  living  apartments, 
storerooms,  etc.  In  sailing  vessels  and  in  freighters  the  net  tonnage 
may  be  taken  as  the  cubic  capacity  of  the  hold.  In  estimating  freight, 
40  cubic  feet  of  merchandise  is  considered  a  ton,  provided  the  bulk 
does  not  weigh  more  than  2,000  pounds.  This  ton,  used  as  a  commer- 
cial unit  for  freight  charges,  must  not  be  confused  with  the  registered 
tonnage  based  upon  the  measurement  of  the  vessel. 

In  fumigating  vessels  for  yellow  fever,  plague,  and  other  insect-  or 
animal-borne  diseases,  the  fumigation  should  be  simultaneous  in  all 
parts  of  the  vessel.  Following  this,  special  rooms  and  apartments  may 
be  given  individual  treatment,  depending  upon  circumstances. 

The  empty  compartments  of  an  iron  steamer  may  be  disinfected  by 
steam,  provided  it  is- above  the  water  line.  The  compartments  of  such 
vessels  usually  have  steam  pipes  for  use  in  case  of  fire.  Clothing  and 
other  fabrics  may  also  be  disinfected  by  steam,  by  exposing  them  in  the 
compartment. 

The  water  tanks  and  casks  of  vessels  sometimes  need  special  treat- 
ment. The  water  may  be  infected  with  cholera,  typhoid,  dysentery, 
or  other  water-borne  infection.     The  water  may  be  disinfected  in  situ 


382  SOME    GENEEAL    CONSIDEEATIONS 

by  the  addition  of  chlorinated  lime,  using  an  amount  sufficient  to  make  a 
one  per  cent,  solution.  This  should  stand  at  least  24  hours  before  it  is 
j)umped  out. 

^Yater  casks  on  sailing  vessels  are  very  apt  to  be  breeding  places  for 
mosquitoes.  These  should  be  emptied  and  cleansed.  The  water  con- 
taining the  larvae  may  be  spilled  overboard,  as  neither  the  Anopheles 
nor  the  Stegomyia  develop  in  salt  water,  otherwise  the  larvae  should 
first  be  destroyed. 

For  the  destruction  and  treatment  of  rats,  etc.,  on  vessels  see  pages 
267  and  277. 

Cargo. — As  a  rule,  the  cargo  of  a  vessel  infected  with  pestilential 
disease  needs  no  disinfection.  Individual  articles  of  the  cargo,  such  as 
rags,  household  goods,  second-hand  articles,  or  food  products,  from  in- 
fected localities  may  need  treatment.  New  articles  of  merchandise  or 
new  manufactured  goods  seldom  carry  infection. 

In  the  case  of  plague  the  cargo  may  need  special  treatment  on  ac- 
count of  rats  (see  page  374). 

Ballast. — Vessels  bring  two  kinds  of  ballast:  (1)  water,  (2)  solid. 
Solid  ballast  consists  of  the  greatest  variety  of  substances.  The  kind 
which  is  most  objectionable  from  the  standpoint  of  the  health  officer  is 
called  "sand"  by  the  captain,  but  an  inspection  of  this  sand  will  dis- 
cover the  fact  that  it  often  consists  largely  of  street  sweepings  and  rub- 
bish from  the  port  from  which  the  vessel  hails.  Such  ballast  should  not 
be  unloaded  on  the  city  front,  especially  if  it  comes  from  an  infected 
district.  Ballast  consisting  of  clean,  hard  rock  or  sand  from  the  beach 
is  not  apt  to  carry  infection  of  any  kind,  and  usually  needs  no  attention 
from  the  quarantine  officer. 

Modern  vessels  all  use  water  ballast.  The  tanks  may  be  filled  from 
a  river,  fresh  water  lake,  or  other  body  where  cholera,  typhoid,  or  dysen- 
tery prevails.  It  is  a  rule  in  quarantine  practice  to  require  vessels  in 
fresh  water  ballast  from  cholera-infected  districts  to  return  to  the  open 
sea,  where  the  ballast  tanks  are  pumped  out  and  refilled  with  salt  water, 
provided  this  has  not  been  done  on  the  high  seas.  Before  the  water  is 
pumped  out  it  should  be  treated  with  chlorinated  lime. 

Foreign  Inspection  Service. — To  aid  the  quarantine  officer  every 
American  consul  is  required  to  report  regularly  certain  facts  concern- 
ing the  presence  and  progress  of  epidemic  diseases.  Medical  officers  of 
the  government  are  also  stationed  at  various  countries  in  order  to  su- 
pervise the  sanitary  condition  of  vessels,  their  cargo,  and  passengers 
leaving  for  the  United  States.  This  may  be  called  preventive  quaran- 
tine, for  it  is  a  distinct  help  in  keeping  out  infection  and  facilitates 
trade  and  travel.  Thus,  in  Italy,  during  the  cholera  tiines,  an  officer  of 
the  Public  Health  and  Marine  Hospital  Service  stationed  at  Naples  sue- 
<;essfuUj  kept  that  disease  off  vessels  sailing  from  Naples  to  the  United 


QUAEANTINB  383 

States,  whereas  vessels  sailing  from  Naples  to  other  ports  and  without 
sanitary  supervision  carried  -cholera  in  several  instances. 

National  versus  State  Quarantine. — All  the  maritime  quarantines  in 
this  country  are  now  controlled  by  the  national  government,  except- 
ing the  port  of  New  York,  where  the  quarantine  is  in  the  hands  of  the 
state.  At  a  few  other  ports  a  local  quarantine  is  maintained  in  addi- 
tion to  the  national  service.  The  federal  quarantine  service  is  admin- 
istered by  the  Public  Health  Service,  a  bureau  in  the  Treasury  Depart- 
ment. 

It  is  evident  that  maritime  quarantine  should  be  administered  uni- 
formly so  as  not  to  prejudice  or  favor  the  commerce  of  a  port.  Not 
only  is  uniformity  insured  by  a  central  service,  but  there  is  a  decided 
gain  in  efficiency  for  obvious,  reasons.  Maritime  quarantine  deals  mainly 
with  foreign  shipping.  The  Constitution  reserves  for  the  federal  gov- 
ernment the  right  of  treating  with  foreign  powers;  from  this  point, 
therefore,  maritime  quarantine  is  mainly  a  function  of  the  federal  gov- 
ernment. 

Interstate  Quarantine. — In  accordance  with  our  Constitution  the 
federal  government  has  limited  power  within  the  state,  but  has  practi- 
cally unlimited  authority  to  prevent  the  spread  of  infection  from  one 
state  or  territory,  or  the  District  of  Columbia,  to  another  state  or  terri- 
tory, or  the  District  of  Columbia.  Interstate  quarantine  involves  in- 
terstate travel  and  commerce ;  the  pollution  of  streams  flowing  through 
more  than  one  state;  railroad  and  steamboat  sanitation,  and  all  similar 
questions.  Congress  has  passed  a  comprehensive  act,  Section  III  of  the 
Act  of  February  15,  1893,  authorizing  the  Public  Health  and  Marine 
Hospital  Service  to  enforce  interstate  quarantine  in  the  case  of  con- 
tagious and  infectious  diseases.  The  regulations,  however,  prepared 
under  this  act  comprehended  only  the  six  quarantinable  diseases,  and  have 
only  occasionally  been  enforced  in  the  case  of  yellow  fever,  cholera,  or 
plague. 

There  are  few  interstate  regulations  concerning  typhoid  fever, 
tuberculosis,  measles,  and  other  non-quarantinable  diseases.  It  is  evi- 
dent that  this  is  one  of  the  important  phases  in  which  government 
activity  can  accomplish  especial  good;  for,  while  the  government  has 
limited  power  within  the  state,  it  has  practically  unlimited  authority 
so  far  as  interstate  relations  are  concerned.  Widespread  diseases  will 
never  be  adequately  controlled  by  the  local  authorities  without  the  co- 
operation of  the  government.  It  is  evident  that,  if  one  state  should  rid 
itself  of  typhoid  fever,  measles,  or  tuberculosis,  it  would  soon  become 
reinfected  from  the  neighboring  states.  Interstate  sanitation  is  one  of 
the  burning  questions  needing  vigorous  action  and  cannot  be  adequately 
enforced  without  extending  the  scope  and  powers  of  the  present  federal 
health  authorities. 


384  SOME    CENEEAL    CONSIDERATIONS 

ISOLATION 

In  theory  isolation  is  the  most  perfect  single  method  to  check  the 
spread  of  a  communicable  disease.  The  results  in  practice,  however, 
have  been  somewhat  disappointing  on  account  of  unusual  difficulties. 
The  statement  has  frequently  been  made,  especially  with  reference  to 
typhoid  fever,  that  if  all  the  cases  could  be  isolated  (which  includes 
the  disinfection  of  the  discharges)  we  would  soon  see  an  end  of  the 
infection.  We  now  know  that  this  statement  is  not  true,  on  account 
of  the  bacillus  carriers  and  the  mild  and  unrecognized  or  "missed" 
cases.  Because  the  isolation  of  the  reported  cases  represents  only  a 
portion  of  all  the  foci  of  infection  and,  therefore,  at  best  could  not  in 
itself  control  an  epidemic  disease,  discredit  has  been  thrown  upon  this 
procedure,  which  is  one  of  the  essential  features  of  all  systems  of  pre- 
vention. As  a  matter  of  fact,  it  has  been  shown  that  in  certain  diseases, 
like  measles,  which  is  communicable  for  three  days  or  more  before  the 
nature  of  the  disease  is  recognized,  isolation  has  practically  no  influ- 
ence in  diminishing  the  prevalence  of  this  widespread  infection.  It  is 
true  ordinarily  that  a  case  of  measles  does  most  harm  before  it  is 
isolated;  nevertheless,  this  is  no  reason  why  it  should  be  permitted  to 
further  endanger  the  community.  The  value  of  isolation  is  also  dimin- 
ished by  the  prevalence  of  carriers.  In  fact,  its  practical  usefulness  in 
a  given  infection  is  inversely  proportional  to  the  number  of  carriers. 

If  each  case  isolated  prevents  on  the  average  only  one  other  fresh 
infection,  there  would  still  be  justification  sufficient  to  continue  the 
practice.  As  a  matter  of  fact,  the  practical  value  of  isolation  varies  with 
each  disease,  depending  upon  the  degree  of  its  communicability,  the 
time  when  it  is  communicable,  the  promptness  by  which  it  may  be 
recognized,  the  modes  by  which  it  is  transferred,  the  existence  of  latent 
infections,  missed  cases,  carriers,  and  other  factors  which  influence  the 
spread  of  the  infection. 

Young  ^  reports  the  results  obtained  from  three  degrees  of  isolation  in 
the  home : 

A — Isolation  with  trained  attendant. 
B — Isolation  without  trained  attendant. 

C — Impossible  to  isolate  for  lack  of  room  for  exclusive  use  of  the 
patient. 

It  was  found  in  the  case  of  scarlet  fever  1.087  per  cent,  of  secondary 
cases  occur  in  Class  A,  5.22  per  cent,  in  Class  B,  and  6.9  per  cent,  in 
Class  C.  Cases  cared  for  in  hospital  showed  2.32  per  cent,  of  secondary 
cases.  In  the  case  of  diphtheria  there  were  no  secondary  cases  in 
^Jour.  A.  M.  A.,  Feb.  6,   1915,  LXIV,  6,  p.  488. 


ISOLATION  385 

Class  A,  1.18  per  cent,  in  Class  B,  4.88  per  cent,  in  Class  C,  and  .15  per 
cent,  in  those  treated  in  hospital.  These  figures  clearly  show  that  the 
value  of  isolation  depends  upon  the  intelligence  and  care  with  which  it 
is  carried  out. 

The  degree  of  isolation  varies  markedly  with  the  different  infections. 
A  case  of  yellow  fever  may  be  isolated  under  a  mosquito  screen,  and  a 
case  of  diphtheria  or  scarlet  fever  may  be  effectively  isolated  in  a  bed  in  a 
general  ward,  provided  intelligent  and  painstaking  care  is  exercised  to 
destroy  the  infection  as  it  leaves  the  body.  Isolation  of  the  more  read- 
ily communicable  diseases,  as  smallpox  and  measles,  should  be  much 
more  absolute.  Typhoid  bacillus  carriers  need  not  be  imprisoned.  It 
is  sufficient  to  limit  their  activities,  especially  to  prevent  their  occupation 
in  kitchens,  dairies,  or  about  foodstuffs.  There  is  no  good  reason  to 
isolate  a  consumptive  or  leper  without  open  lesions — that  is,  cases  in 
which  the  bacilli  are  imprisoned  in  the  tissues  and  not  discharged  into 
the  environment.  A  careful  consumptive  or  leper  may  be  allowed  a 
wide  latitude.  On  the  other  hand,  isolation  in  chronic  infections,  such 
as  tuberculosis  and  leprosy,  with  open  lesions,  is  the  most  helpful  and 
at  the  same  time  the  most  difficult  single  procedure  we  have  to  control 
their  spread.  The  careless,  indigent,  ignorant,  or  helpless  consumptive 
is  a  public  menace  that  needs  energetic  and  sometimes  arbitrary  iso- 
lation. 

Isolation  may  most  readily  and  effectively  be  carried  out  in  hospitals 
or  sanatoria.  Proper  isolation  in  the  home  requires  a  special  room 
or  rooms,  intelligent  nursing,  appliances  for  disinfection,  etc.,  a  com- 
bination often  difficult  to  arrange.  House  quarantine  varies  with  the 
different  diseases.  To  carry  it  out  rigorously  in  all  cases  and  under  all 
conditions  is  folly.  Different  diseases  need  different  procedures.  Some- 
times it  is  sufficient  simply  to  placard  the  house  as  a  warning.  At  other 
times  it  may  be  necessary  to  station  sanitary  guards  about  the  premises 
to  enforce  the  quarantine.  The  imperfections  of  strict  isolation  by  the 
"shutting  in  of  houses"  are  graphically  described  in  Defoe's  "Journal  of 
the  Plague  Year." 

Isolation  camps  or  temporary  barracks  in  times  of  epidemics  are 
effective  measures  in  checking  the  spread  of  some  infections.  This 
method  has  proved  effective  in  actual  practice  in  the  case  of  smallpox, 
yellow  fever,  plague,  cholera,  and  other  diseases. 

It  often  becomes  a  difficult  question  to  determine  whether  the  well 
members  of  a  household  should  also  be  quarantined — especially  whether 
the  well  children  should  be  permitted  to  attend  school.  This  perplex- 
ing question  must  be  decided  for  each  disease  separately,  and  the  deci- 
sion in  each  disease  is  sometimes  modified  by  attending  factors.  Usually 
the  other  children  in  the  family  in  the  case  of  scarlet  fever  are  excluded 
from  school  for  four  weeks  from  the  beginning  of  the  last  case.  In 
14 


386  SOME    GENERAL    CONSIDERATIONS 

most  cities  tlie  same  rule  holds  for  diphtheria,  although  here  we  are 
able  to  determine  whether  the  children  are  bacillus  carriers  or  not. 
At  least  two  negative  cultures  from  the  nose;  and  throat  should  be  re- 
quired before  such  children  are  allowed  freely  to  mingle  with  other 
children.  The  principal  factors  which  determine  whether  the  well 
children  in  a  family  shall  be  permitted  to  attend  school  or  not  in  any 
particular  infection  rest  upon  our  knowledge  as  to  whether  the  disease 
is  conveyed  by  a  third  person  and  the  frequency  of  bacillus  carrying 
and  missed  cases. 

Isolation  becomes  one  of  our  most  valuable  public  health  measures 
when  communicable  diseases  affect  persons  working  about  milk,  meat, 
and  other  foods  capable  of  conveying  infection. 

One  of  the  practical  objections  to  isolation  and  one  reason  that  it 
.meets  with  so  much  opposition  from  the  public  is  that  the  compensa- 
tion of  the  wage  earner  ceases  through  no  fault  of  his  own.  It  is  evi- 
dently unjust  to  practically  imprison  and  punish  a  wage-earner  for  the 
good  of  the  community,  because  he  or  some  member  of  his  family  has 
contracted  an  infection,  perhaps  through  some  fault  of  the  community 
itself.  It  is,  therefore,  reasonable  and  just  that  wage  earners  and  others 
should  be  compensated  and  their  personal  interests  safeguarded  during 
enforced  isolation. 

Isolation  only  reduces  to  a  moderate  degree  the  prevalence  of  dis- 
ease. The  limitations  of  this  valuable  procedure  are  now  well  under- 
stood. With  improved  methods  of  diagnosis  and  increased  knowledge 
of  the  methods  of  spread  of  disease,  isolation  will  be  made  increasingly 
effective.  Every  case  isolated  is  a  focus  of  infection  neutralized.  Al- 
though not  as  satisfactory  in  practice  as  it  is  in  theory,  isolation  will 
ever  remain  one  of  the  chief  administrative  procedures  for  the  control 
of  the  communicable  diseases. 

In  the  past,  geographic  isolation  was  one  of  the  safeguards  of  the 
people  against  disease,  but  iii  modern  times,  since  all  means  of  trans- 
poration  have  improved,  and  communication  has  become  more  extended 
and  more  rapid,  the  diffusion  of  infection  is  facilitated. 

Nuisances.- — A  nuisance  may  be  defined  as  "the  use  of  one's  property 
in  such  a  way  as  to  injure  the  rights  of  others,  and  to  inflict  damages.'-' 
Popularly  a  nuisance  is  an  annoyance.  Statutory  definitions  are  usually 
more  explicit  and  include  nuisances  not  directly  related  to  public  health. 
A  comprehensive  statutory  definition  is:  "Whatever  is  dangerous  to 
human  life,  and  whatever  renders  soil,  air,  water,  or  food  impure  or 
unwholesome,  are  declared  to  be  nuisances,  and  every  person,  either 
owner,  agent,  or  occupant,  having  aided  in  creating  or  contributing  to 
the  same,  or  who  may  suffer  to  continue  or  retain  any  of  them  shall  be 
deemed  guilty  of  a  misdemeanor."  ^ 

^Utah,  Chapter  45  of  1889,  Sec.   1. 


ISOLATION  387 

The  following  are  considered  nuisances  in  different  states  and  cities : 
Filth,  such  as  garbage,  ashes,  and  slops,  either  on  private  property  or  on 
public  highways;  cesspools,  privy  vaults,  sink  drains,  dumps,  and  dirty 
yards;  low,  wet,  and  soggy  lands;  defective  plumbing  and  draining; 
faulty  cellars;  overcrowding  of  tenements  and  lodging  houses,  or  dwell- 
ings unfit  for  habitation ;  excavations ;  weeds ;  flowers  with  offensive 
odors;  foul  closets  on  railroad  coaches;  dirty  street  cars;  use  of  salt  on 
streets  in  snowy  weather;  disturbing  noises;  spitting  in  puljlic  places; 
keeping  of  horses  and  cattle  in  city  limits;  manure;  hogs;  hog-pens, 
stables  and  barns ;  fowls ;  dead  animals ;  filthy  shores ;  stagnant  water  and 
marshes;  offensive  businesses  and  trades;  places  where  liquor  is  sold 
illegally;  and  offenses  against  decency.  While  some  of  these  conditions 
may  favor  the  spread  of  the  communicable  diseases,  yet  most  nuisances 
are  no  more  serious  than  annoyances  to  the  senses. 

The  phrase,  "source  of  filth  or  cause  of  sickness"  used  in  the  statutes 
of  no  less  than  fourteen  states,  is  copied  verbatim  from  a  law  enacted  in 
Massachusetts  in  1797.  At  that  time  miasmatic  vapors  and  the  inhala- 
tions from  decomposing  organic  matter  were  believed  to  be  the  principal 
causes  of  the  contagious  diseases.  The  Supreme  Court  of  Massachu- 
setts, however,  has  ruled  that  "in  order  to  amount  to  a  nuisance  it  is  not 
necessary  that  the  corruption  of  the  atmosphere  should  be  such  as  to  be 
dangerous  to  health;  it  is  sufficient  that  the  effluvia  are  offensive  to  the 
senses  and  render  habitations  uncomfortable.'^ 

By  far  the  greatest  number  of  all  the  complaints  reaching  the 
health  authorities  deal  with  real  or  supposed  nuisances.  There  seems  to 
be  a  widespread  belief  that  the  chief  function  of  the  health  officer  is  the 
abatement  of  nuisances.  Formerly  the  health  officer  was  a  general 
scavenger  and  his  main  duties  consisted  in  looking  after  nuisances. 
ISTuisances  often  clog  the  health  office  and  crowd  out  more  important 
sanitary  and  hygienic  matters.  In  most  complaints  the  question  at  issue 
is  whether  the  nuisance  exists  or  not — a  question  of  fact  which  could 
be  decided  just  as  well  by  the  police  courts  as  by  a  board  of  health  or 
health  officer.  However,  the  abatement  of  nuisances  is  usually  assigned 
to  the  health  authorities  by  statutory  enactment. 

In  a  few  cities,  especially  those  with  liberal  charters,  the  ordinances 
covering  nuisances  are  so  definite  and  explicit  that  an  inspector  may 
determine  a  nuisance  and  issue  an  order  for  its  abatement.  In  cases 
where  condemnation  of  property,  involving  property  of  some  value,  such 
for  example  as  when  an  offensive  trade  is  alleged  to  be  a  nuisance,  it  is 
usually  necessary  to  prove  the  case  in  court  before  the  nuisance  can  be 
abated.  In  court,  substantial  injury  must  be  shown  and  the  health  officer 
should  be  sure  he  has  the  facts  as  to  the  nuisance  before  he  appears  in 
court.  He  will  be  required  by  the  court  to  establish  the  source,  fre- 
quency, and  nature  of  the  odors,  or  whatever  is  alleged  to  be  the  nuisance. 


388  SOME    GENERAL    CONSIDERATIONS 

It  is  exceedingly  difTicnlt  to  estal)lish  the. fact  that  many  nuisances  are 
dangerous  to  the  health  of  the  community  and  the  cause  of  sickness. 

In  general  two  methods  are  followed  for  the  control  of  nuisances: 
(1)  prevention;  (2)  abatement.  The  first  is  the  wisest  and  aims  to 
regulate  and  control  the  different  conditions  likely  to  cause  a  nuisance 
or  even  to  prohibit  them.  The  second  merely  provides  legal  steps  for 
their  abatement.  There  are  at  least  four  ways  in  law  of  dealing  with 
nuisances:  (1)  By  criminal  action ;  (2)  by  injunction ;  (3)  by  damages 
(private  suit) ;  (4)  by  abatement  under  statutory  powers. 

COLLATERAL  READING 

W.  T.  Sedgwick :  "Principles  of  Sanitary  Science  and  the  Public 
Health,"  1902. 

C.  Y.  Chapin :     "Sources  and  Modes  of  Infection,"  1912. 

:     "Municipal  Sanitation  in  the  United  States,"  1901. 

M.  Eubner:  M.  V.  Gruber,  and  M.  Picker:  Handhuch  der  Hygiene, 
1911. 

Carl  Pliigge :     Grundriss  der  Hygiene,  1908. 

Theodore  Weyl :     Handhuch  der  Hygiene,  Jena,  1895. 

H.  B.  Hemenvpay,  Legal  Principles  of  Public  Health  Administration, 
1914. 


SECTION   II 
IMMUNITY,  HEREDITY,  AND  EUGENICS 

CHAPTER    I 
IMMUNITY 

Immunity  or  resistance  to  disease  is  the  very  foundation  of  pre- 
ventive medicine.  It  is  the  overshadowing  factor  in  hygiene.  In  this 
sense  we  use  the  term  "hygiene"  to  include  the  care  of  the  person,  in 
contradistinction  to  "sanitation,"  which  deals  with  the  environment. 
There  is  no  sharp  line  of  demarcation — we  speak  of  hygiene  of  the 
teeth,  of  sleep,  of  bathing,  of  exercise,  of  food  and  drink,  and  of  those 
conditions  which  are  more  or  less  intimately  associated  with  the  body. 
We  speak  of  the  sanitation  of  the  home,  of  schools,  of  cities,  of  farms. 
Sanitary  science  considers  the  air,  soil,  climate,  and  our  surroundings 
as  they  affect  health.  Sanitation,  then,  is  largely  impersonal;  hygiene 
is  personal,  and,  as  far  as  the  prevention  of  disease  is  concerned,  one  of 
the  most  important  factors  in  hygiene  is  immunity. 

The  word  "immunity"  is  a  very  old  term — we  still  speak  of  immu- 
nity to  crime,^  but  it  is  only  of  late  years  that  we  are  beginning  to  un- 
derstand the  mechanism  by  which  the  body  protects  itself  against  in- 
fection. The  advances  have  been  so  rapid  that  these  studies  may  now  be 
grouped  into  a  separate  science  known  as  Immunology. 

Immunity  is  a  function  of  all  living  beings  (animals  and  plants), 
and  in  its  widest  form  is  one  of  the  fundamental  properties  of  life. 
Tbus,  as  long  as  we  are  alive  the  colon  bacillus  in  our  intestinal  tract 
and  the  spores  of  the  hay  bacillus  on  our  skins  do  us  no  harm,  but  the 
moment  we  die,  and  ofttimes  shortly  before  death,^  these  and  other  bac- 
teria invade  our  tissues  and  disintegrate  them. 

Immunity  may  be  defined  as  the  power  which  certain  living  organ- 
isms possess  of  resisting  infections.  Immunity  is  the  contrary  condi- 
tion to  susceptibility.  Hypersusceptibility  is  a  special  state  of  an  exag- 
gerated power  of  reaction  and  will  be  discussed  separately  under  anaphy- 
laxis or  allergic.     The  word  resistance  has  practically  the   same   sig- 

^  We  may  speak  of  immunity  "from"  a  disease,  "to"  a  disease,  and  "against" 
a  disease. 

'^  Terminal  infections. 

389 


390  IMMUNITY 

iiification  as  immunity.  The  term  "tolerance''  is  eommonly  nsed  to 
describe  a  limited  form  of  immunity  usually  acquired  by  the  repeated 
use  of  alkaloids,  alcohol,  and  other  poisons  of  comparatively  simple 
chemical  structure.  While  a  high  degree  of  tolerance  may  be  acquired 
to  such  substances,  a  true  immunity  in  the  sense  in  which  tlui  term  is 
now  used  is  never  produced.  In  the  case  of  tolerance,  antibodies  arc 
not  found  in  the  blood.  For  the  most  part  true  innniinity  is  produced 
against  colloidal  substances,  wdiile  tolerance  is  largely  limiicd  to  tlic 
crystalloids;  this  distinction,  however,  is  not  absolute. 

There  are  all  gradations  and  various  kinds  of  immunity.  It  varies  in 
degree  from  the  weakest  appreciable  amount  to  an  absolute  protection. 
It  also  varies  greatly  in  duration — from  the  briefest  period  to  a  life  span. 
Immunity,  therefore,  is  a  relative  term.  It  may  be  natural  or  acquired, 
active  or  passive,  local  or  general,  pure  or  mixed,  specific  or  general, 
family  or  racial,  brief  or  lasting,  strong  or  weak,  etc. 

Immunity  is  a  function  which  is  not  limited  to  man  and  other  mem- 
bers of  the  animal  kingdom.  It  is  common  throughout  the  plant  king- 
dom. We  are  indebted  to  Welch  for  the  thought  that  the  bacteria 
themselves  also  have  this  fundamental  property  of  life.  Thus,  man  is 
susceptible  to  the  tubercle  bacillus  because  the  tubercle  bacillus  is  im- 
mune to  man;  on  the  other  hand,  man  is  immune  to  the  hay  bacillus 
because  the  hay  bacillus  is  susceptible  to  man.  In  this  sense  a  micro- 
organism is  called  pathogenic  or  saprophytic,  depending  upon  whether  it 
harms  or  is  favored  by  its  host.  This  is  the  relation  between  seed  and 
soil.  A  fertile  soil  is  susceptible;  a  barren  soil  is  immune.  The  seed 
in  the  first  instance  may  be  pathogenic;  in  the  second  non-pathogenic. 
The  host  is  able  to  resist  the  intrusion  and  growtli  of  the  non-pathogenic 
microorganisms  and  protect  itself  against  harm  through  its  mechanism 
of  immunity.  If  the  protecting  devices  are  insufficient  to  guard  against 
attack,  the  germs  multiply,  produce  poisonous  substances,  or  harm  the 
host  in  other  ways.  The  reason  that  the  same  microorganism  may  be 
pathogenic  for  one  host  and  harmless  for  another  depends  upon  the 
presence  or  lack  of  immunity.  The  virulence  of  a  microorganism  is  an 
expression  of  the  intensity  of  the  relation  between  the  seed  and  the  soil. 
Virulence  may  be  strengthened  or  attenuated  either  by  increasing  or  de- 
creasing the  resistance  of  the  host  or  by  increasing  or  decreasing  the 
resistance  of  the  microbe. 

Mechanism  of  Immunity — Theories  of  Immunity.— It  is  now  quite 
evident  that  the  mechanism  of  immunity  varies  in  different  infections 
and,  to  a  certain  extent,  even  in  the  same  infection  under  different  con- 
ditions. It  must  further  be  admitted  that  we  are  still  in  ignorance  of 
the  mechanism  by  which  the  body  protects  itself  against  many  diseased 
states. 

Plistorically  considered,  immunology  as  a  science  dates  back  scarcely 


IMMUNITY  391 

30  years.  Many  primitive  people  attempted  to  immunize  themselves  in 
a  crude  sort  of  way.  but  with  methods  now  recognized  as  essentially 
sound.  Thus,  South  African  tribes  tried  to  protect  themselves  against 
snake  bites  by  using  a  mixture  of  snake  venom  and  gum;  the  Moors 
immunized  cattle  to  pleural  pneumonia  by  placing  some  of  the  virus 
under  the  skin  of  the  animal.  The  inoculation  against  smallpox  used 
from  time  immemorial,  and  vaccination  with  cowpox  introduced  by 
Jenner  in  1798,  are  examples  of  the  first  j)ractical  use  of  specific  methods 
in  the  history  of  immunity. 

Pasteur  was  greatly  influenced  by  Jenner's  demonstration  that  a 
mild  form  of  a  disease  protects  against  the  severe  form.  Pasteur  ex- 
panded the  fact  taught  by  Jenner  into  a  general  principle.  Practically 
all  of  Pasteur's  work  in  immunity  that  bore  practical  fruit,  such  as 
vaccinations  against  chicken  cholera,  anthrax,  and  rabies,  is  based  upon 
this  guiding  principle. 

Pasteur  in  1888  expounded  his  "exhaustion"  theory,  which  was  the 
first  attempt  at  a  scientific  explanation  of  immunity.  Pasteur  was  a 
chemist  and  his  theory  was  a  simple  chemical  conception,  largely  based 
upon  his  work  upon  the  fermentation  of  sugar  with  yeasts.  He  re- 
garded the  body  immune  because  its  food  supply  was  used  up  and  the 
microorganisms  could,  therefore,  no  longer  grow — just  as  yeasts  cease 
to  grow  when  the  sugar  is  used  up  in  a  culture  medium.  It  is  now 
easy  to  disprove  the  exhaustion  theory.  Bacteria  do  not  cease  to  grow 
on  account  of  the  exhaustion  of  the  food  supply,  but  rather  on  account 
of  the  production  of  products  toxic  to  themselves.  Further,  bacteria 
may  grow  well  enough  in  the  dead  tissues  and  fluids  of  immune  animals, 
and,  again,  immunity  may  be  induced  by  the  inoculation  of  dead  bac- 
terial products,  substances  which  can  hardly  use  up  food  material.  Ee- 
cently  Pasteur's  exhaustion  theory  has  been  revived  in  a  modified  form 
by  Ehrlich,  who  considers  that  there  is  sufficient  evidence  of  this  form 
of  immunity  in  certain  cases,  as  in  cancer.  Ehrlich  calls  it  "atreptic" 
immunity. 

Chauveau  proposed  the  "retention"  theory,  the  exact  opposite  of  the 
exhaustion  theory.  This  theory  is  also  based  upon  the  analogy  of  the 
behavior  of  bacterial  growth  in  vitro  compared  to  their  growth  within 
the  body.  It  soon  became  evident  that  bacterial  growth  ceases  even 
though  abundant  food  is  present,  and  that  this  inhibition  is  due  to  the 
retention  of  products  of  metabolism  of  bacterial  activity.  Chauveau 
considers  that  such  substances  are  retained  within  the  body,  which  thus 
protects  it  against  further  growth  and  development  of  the  microorganisms 
and  thus  accounts  for  immunity. 

The  above  theories  are  generalizations  which  have  now  little  more 
than  historical  interest.  We  now  know  that  no  one  mechanism  of  im- 
munity will  explain  all  cases.     In   some   instances  phagocytosis  plays 


392  IMMUNITY 

iiii  important  part;  in  others  antibodies  of  various  sorts;  the  side-chain 
llieory  appears  to  account  for  most  of  the  facts  iii  antitoxic  immniiity. 
Jn  some  cases  the  immunity  is  due  to  a  negative  property  in  tliat  ilicr(! 
is  an  absence  of  specific  affinity  between  the  poison  and  the  cells.  In 
others  it  is  a  positive  factor  and  is  due  to  the  presence  of  substances 
able  to  neutralize  the  toxic  action.  The  mechanism  of  immunity  in 
some  instances  resides  mainly  in  the  blood  and  fluids;  in  other  cases 
it  is  evidently  more  directly  associated  with  cellular  activity.  In  some 
instances  immunity  depends  upon  the  power  of  immediate  reaction  in 
the  sense  of  anaphylaxis.  In  all  cases  the  mechanism  is  probably  com- 
plex and  multiple. 

The  unsatisfactory  state  of  our  knowledge  in  certain  fields  of  im- 
munity is  well  illustrated  in  the  case  of  anthrax.  The  mechanism  of 
protection  is  not  at  all  understood  in  this  infection,  which  was  the  first 
and  classic  illustration  of  a  germ  disease.  The  mechanism  of  immunity 
in  common  colds  is  also  complex  and  obscure. 

Our  resistance  to  disease  is  in  many  cases  due  to  a  simple  mechani- 
cal or  chemical  protection  against  the  invasion  of  the  pathogenic  micro- 
organisms; that  is,  the  tissues  are  susceptible  enough,  but  are  guarded 
against  the  invasion  of  the  germs  of  disease.  Many  examples  may  be 
cited  in  this  category.  Thus,  one  of  the  important  functions  of  the 
skin  consists  in  this  mechanical  protection  of  the  tissues  underneath. 
There  is  but  a  single  layer  of  epithelium  between  us  and  death.  The 
smooth  conjunctiva  is  protected  by  the  constant  washing  of  the  tears  and 
the  motion  of  the  eyelids.  The  lungs  are  safeguarded  by  the  shape  of 
the  upper  respiratory  passages  and  the  moisture  of  the  mucous  mem- 
branes, which  act  as  a  mechanical  trap  for  many  bacteria.  Some  of 
those  that  pass  deeper  are  carried  back  by  the  mechanical  action  of  the 
cilia.  The  sensitive  and  susceptible  mucous  membrane  of  the  in- 
testines is  partly  protected  through  the  acidity  of  the  gastric  juice,  which 
is  sufficient  to  destroy  cholera  vibrios  and  other  microorganisms  sus- 
ceptible to  acid. 

Within  the  body  the  mechanism  of  immunity  is  an  adaptation  of 
cell  nutrition.  The  mechanism  varies  with  different  infections  and  in 
different  stages  of  the  same  infection.  In  certain  diseases  the  immunity 
seems  to  reside  mainly  in  the  activity  of  the  cells.  In  other  diseases 
the  immunity  is  due  chiefly  to  substances  floating  in  the  blood.  The 
first  is  the  cellular  and  the  second  the  humoral  theory.  As  we  shall 
have  occasion  to  see,  the  immune  bodies  in  the  blood  are  probably  in 
all  cases  derived  from  the  cells,  so  that  the  cells  play  the  fundamental 
part  in  most  cases  of  immunity.  However,  the  great  majority  of  the 
studies  in  immunology  have  been  focused  upon  the  changes  in  the  blood. 
This  is  not  due  to  the  fact  that  the  blood  alone  represents  these  changes, 
but  that  it  best  represents  them,  and  thus  affords  the  readiest  method 


IMMUNITY  393 

of  attacking  the  problem.  The  blood  is  the  most  fluid  and  most  cos- 
mopolitan of  all  the  tissues  of  the  body,  visiting  every  part,  bearing  to 
each  part  certain  substances,  and  removing  from  each  part  certain  other 
substances.  It  is  evident  that  it  is  easy  to  study  the  blood  and  its 
changes,  as  some  of  it  may  readily  and  repeatedly  be  withdrawn  during 
life  in  order  to  observe  its  changes  without  in  any  way  harming  the 
animal.  The  fundamental  processes  of  immunity  within  the  body  must 
all  depend  upon  some  chemical  change,  but  we  know  very  little  con- 
cerning the  chemical  composition  of  the  substances  that  play  the  chief 
role  or  the  chemical  nature  of  the  changes.  Great  advances  have  been 
made  in  immunology  despite  this  lack  of  chemical  knowledge;  for  these 
advances  we  are  indebted  to  experimental  biology,  through  which  we 
have  learned  the  results  of  many  effects  without  a  knowledge  of  their 
nature  or  the  intimate  processes  concerned. 

Natural  Immunity. — Natural  immunity  is  an  inherited  character 
possessed  in  common  by  all  individuals  of  a  given  species.  It  is  in- 
herent to  a  greater  or  less  extent  in  all  members  of  that  species.  It 
may  be  present  at  birth  or  develop  in  later  years.  There  are  very  many 
examples  of  natural  immunity.  Thus,  most  of  the  communicable  in- 
fections of  man  are  peculiar  to  man;  that  is,  the  lower  animals  have  a 
natural  immunity  to  such  diseases  as  measles,  mumps,  scarlet  fever, 
typhoid  fever,  cholera,  gonorrhea,  syphilis,  yellow  fever,  malaria,  leprosy, 
and  so  on  through  a  long  repertoire.^  Even  tuberculosis,  which  is  the 
most  common  and  widespread  of  infections,  has  its  own  particular 
bacillus  to  which  man  is  especially  susceptible  and  to  which  the  lower 
animals  show  a  marked  degree  of  natural  immunity.  On  the  other 
hand,  man  shows  a  high  grade  of  natural  immunity  to  a  large  number 
of  infections  to  which  the  lower  animals  are  subject,  as  rinderpest, 
black  leg  (symptomatic  anthrax),  Texas  fever,  etc. 

The  monopoly  which  man  possesses  of  being  susceptible  to  infec- 
tions which  the  lower  animals  successfully  resist  is  not  confined  to  the 
bacteria  alone,  but  includes  many  protozoa  and  higher  animal  parasites. 
Thus,  the  hookworm  of  man  is  different  from  the  hookworm  of  the  horse, 
the  dog,  the  seal.  Each  host  has  its  own  species  of  hookworm  which, 
though  closely  allied,  are  not  interchangeable.  That  is,  the  horse  has  a 
natural  immunity  to  the  hookworm  that  is  parasitic  for  man,  and  vice 
versa. 

There  is  a  group  of  infections,  including  the  pyogenic  cocci,  an- 
thrax, tetanus,  malignant  edema,  glanders,  actinomycosis,  rabies,  plague, 
foot-and-mouth  disease,  malta  fever,  tuberculosis,  milk  sickness,  infec- 
tions with  the  paratyphoid  bacillus,  ringworm,  and  many  higher  forms 

^  It  is  true  that  some  of  these  infections  may  be  conveyed  to  monkeys  or 
other  animals  by  artificially  introducing  large  amounts  of  the  virus,  but  these 
animals  do  not  contract  these  diseases  naturally  and  therefore  show  a  high  degree 
of  natural  immunity. 


394  IMMUNITY 

of  animal  parasites,  which  are  common  to  many  species  in  widely  dif- 
ferent genera. 

There  are  certain  remarkable  facts  connected  with  natural  immu- 
nity. For  example,  white  mice  are  naturally  immune  to  glanders, 
whereas  the  field,  mouse  possesses  a  high  degree  of  susceptibility.  When 
we  consider  how  slight  must  be  the  differences  in  the  structure,  the  func- 
tion, the  chemistry,  and  the  metabolism  in  the  white  mouse  when  com- 
pared with  its  gray  cousin,  we  begin  to  appreciate  the  subtle  differences 
and.  perhaps  complex  factors  upon  which  immunity  depends.  If  we 
could  find  out,  for  example,  why  the  goat  is  resistant  to  tuberculosis 
while  domestic  cattle  are  particularly  .susceptible,  we  would  have  the 
foundation  for  a  specific  preventive  and  cure  for  that  disease. 

Practically  all  the  individuals  of  a  certain  species  have  about  an 
equal  susceptibility  or  an  equal  immunity  to  a  given  infection.  These 
factors  are  more  constant  than  commonly  supposed.  Laboratory  ani- 
mals react  with  certainty  and  with  striking  uniformity  to  an  infection 
of  known  virulence,  provided  the  virus  is  brought  into  association  with 
certain  tissues.  Thus,  strikingly  uniform  results  are  obtained  from  a 
given  culture  of  plague  introduced  subcutaneously  into  the  guinea-pig, 
or  of  tuberculosis  into  the  peritoneal  cavity  of  the  monkey,  or  of  strep- 
tococci into  the  circulation  of  the  rabbit,  or  of  rabies  under  the  dura 
of  the  dog,  or  of  anthrax  into  the  mouse.  Man  is  no  exception  to  this 
general  statement,  as  far  as  may  be  judged  from  the  data  at  hand. 
Practically  all  persons  are  alike  susceptible  to  smallpox,  yellow  fever, 
tetanus,  and  many  other  infections.  In  epidemics  some  individuals 
escape.  In  other  epidemics  the  disease  varies  greatly  in  severity.  These 
apparent  exceptions  may  not  be  due  so  much  to  varying  degrees  of  im- 
munity, but  rather  to  variations  in  the  dose  and  virulence  of  the  virus, 
the  channel  of  infection,  symbiosis,  and  other  factors. 

In  some  cases  the  immunity  is  so  weak  that  the  balance  between 
health  and  disease  is  quite  unstable.  This  appears  to  be  the  case  with 
tuberculosis  in  man.  We  possess  sufficient  natural  immunity  to  tuber- 
culosis successfully  to  resist  small  amounts  of  infection,  but  this  re- 
sistance may  readily  be  broken  down  by  any  influences  which  undermine 
our  general  vitality. 

Natural  immunity  may  be  broken  down  by  various  means  that 
weaken  the  animal,  such  as  fasting,  the  production  of  an  experimental 
diabetes  with  phloridzin,  fatigue,  excessive  cooling  of  the  body,  as  the 
clipping  of  the  hair  of  thick-furred  animals,  etc.  Thus,  chickens  are 
ordinarily  naturally  immune  to  anthrax,  but  may  be  infected  if  their 
feet  are  kept  in  cold  water.  White  rats  are  resistant  to  anthrax,  but  be- 
come susceptible  if  the  hair  is  clipped. 

Acquired  Immunity. — By  acquired  immunity  is  meant  a  specific 
resistance  to  an  infection  that  is  not  naturally  inherent  in  all  the  in- 


IMMUNITY  395 

(lividiiaLs  of  a  species,  but,  as  the  term  indicates,  the  iiumuuity  is  acquired 
during  the  lifetime  of  the  individual.  Inmiunity  may  be  acquired  either 
through  some  "natural"  event,  such  as  an  attack  of  a  disease,  or  may 
be  "artiticially"  induced  by  the  introduction  of  some  substance,  such  as 
a  serum,  toxin,  vaccine,  or  a  virus. 

Acquired  immunity  may  be  either  active  or  passive.  Active  immu- 
nity is  induced  by  an  attack  of  a  disease  or  by  the  introduction  of  a 
virus  or  suitable  toxin  into  the  system.  Immunity  thus  acquired  is 
active  in  the  sense  that  it  depends  upon  an  aggressive  stimulation  of 
the  protecting  mechanism  as  a  result  of  a  series  of  reactions  within  the 
body.  Passive  immunity,  or  transferred  immunity,  is  an  antitoxic  im- 
munity. It  is  passive  for  the  reason  that  the  antibodies  (antitoxin) 
are  introduced  into  the  body,  which,  therefore,  takes  no  part  in  their 
formation.  The  injection  of  diphtheria  toxin  into  the  horse  causes  an 
active  immunity  in  that  animal ;  the  injection  of  some  of  the  antitoxin 
contained  in  the  horse's  serum  into  a  child  causes  a  passive  immunity  in 
the  child.  Both  are  acquired  because  horse  and  man  have  no  inherent 
or  natural  immunity  to  diphtheria.  The  protection  against  smallpox 
produced  by  vaccination  is  an  example  of  active  immunity ;  so  also  is  the 
immunity  produced  by  bacterial  vaccines. 

Mixed  Immunity. — Mixed  immunity  is  a  combination  of  the  active 
and  passive.  This  is  used  practically  in  plague  prophylaxis  and  has 
been  proposed  for  other  infections.  It  consists  in  injecting  a  mixture 
of  antitoxic  serum  and  the  appropriate  bacterial  virus.  The  advantage 
of  this  procedure  consists  in  the  fact  that  the  passive  or  antitoxic  im- 
munity diminishes  the  severe  reactions  which  sometimes  follow  the  in- 
troduction of  a  bacterial  virus.  It  also  affords  an  immediate  protection 
and  thereby  guards  the  body  during  the  time  it  always  takes  for  the 
active  immunity  to  become  effective. 

How  Active  Immunity  May  Be  Acquired. — Immunity  may  be  ac- 
quired by : 

(a)  An  attack  of  a  disease. 

(b)  By  the  introduction  of  a  virus. 

(c)  By  the  introduction  of  a  vaccine. 

(d)  By  the  introduction  of  a  chemical  product  (toxin). 

(a)  An  Attack  of  the  Disease. — Certain  diseases,  whether  acquired 
naturally  or  induced  artificially,  leave  an  immunity  which  varies  greatly 
in  degree  and  duration.  The  following  diseases  leave  a  definite  immu- 
nity of  high,  though  variable,  grade :  smallpox,  yellow  fever,  measles, 
whooping-cough,  scarlet  fever,  cerebrospinal  meningitis,  infantile  paraly- 
sis, typhoid  fever,  typhus  fever,  chickenpox,  mumps.  Second  attacks 
of  smallpox,  measles,  typhoid  fever,  and  other  infections  in  this  list 


396  IMMUNITY 

arc  not  ■nju-ommon,  ,sliowiiig  that  the  immiiiiity  is  rarely  if  ever  abso- 
lute. 

Some  diseases,  such  as  pneumonia,  erysipelas,  and  malaria,  seem  to 
predispose  to  subsequent  attacks,  that  is,  diminish  resistance.  Even  in 
this  class  of  infections  there  must  be  a  certain  amount  of  immunity, 
however  short,  else  the  patient  would  not  recover. 

The  practice  of  intentionally  inoculating  smallpox  was  the  first  ex- 
ample in  preventive  medicine  in  which  use  was  made  of  the  fact  that 
one  attack  of  a  disease  confers  immunity  to  a  subsequent  attack  of  the 
same  disease.  The  present-day  vaccination  of  cowpox  (a  modified  small- 
pox) may  be  considered  as  belonging  to  this  category.  The  principle 
is  used  to  a  much  greater  extent  in  veterinary  practice  either  by  using 
a  small  amount  of  the  infection  or  by  introducing  it  in  an  unusual 
way  or  by  inoculating  the  animals  at  a  time  when  they  are  found  to  be 
least  susceptible.  In  this  way  a  benign  form  of  the  disease  is  produced 
which  protects  against  the  severe  and  fatal  forms.  These  methods  are 
use  in  Texas  fever,  rinderpest,  pleuropneumonia,  anthrax,  etc. 

(b)  By  the  Introduction  of  a  Virus  Into  the  System. — A  distinc- 
tion is  made  between  a  virus  and  a  vaccine.  If  the  material  used  con- 
tains the  living  active  principle  it  should  be  called  a  virus.  If  the 
virus  is  dead  it  should  be  called  a  vaccine.^ 

The  highest  and  most  lasting  degrees  of  immunity  may  be  produced 
by  the  introduction  of  the  living  active  principle  into  the  system,  thus 
imitating  nature.  The  virus  may  be  diminished  in  virulence  as  in  an- 
thrax, vaccinia,  or  rabies.  A  high  grade  of  immunity  to  plague  and 
cholera  may  be  induced  in  man  by  the  injection  of  living  cultures. 
In  the  case  of  plague  the  cultures  must  be  greatly  diminished  in  viru- 
lence. 

In  the  case  of  cholera  virulent  strains  may  be  used,  as  this  disease  is 
neither  a  bacteremia  nor  septicemia,  and  there  is  very  much  less  danger 
in  introducing  the  cholera  vibrios  into  the  subcutaneous  tissue  than 
in  taking  them  by  the  mouth.  This  principle  of  introducing  the  virus 
into  a  resistant  tissue  can  be  taken  advantage  of  in  various  infections, 
provided  the  virulence  of  the  disease  depends  largely  upon  the  channel 
of  infection.  The  virulence  of  the  virus  may  also  be  diminished  by 
certain  definite  processes,  such  as  growing  the  culture  at  an  unusually 
high  temperature,  as  in  the  case  of  anthrax;  or  by  prolonged  artificial 
cultivation,  as  in  the  classic  instance  of  chicken  cholera;  or  by  drying, 
as  in  rabies;  or  by  passage  through  animals,  as  in  smallpox  (cowpox)  ; 
or  by  growing  on  unfavorable  media ;  by  the  use  of  very  small  amounts 
of  the  virus,  as  in  tuberculosis  and  many  other  infections;  or  by  the 
use  of  closely  related  strains,  such  as  the  human  tubercle  bacillus  for 

^Vaccine  (vacca,  a  cow)  is  not  a  good  term,  but  is  now  too  deeply  rooted  to 

change. 


IMMUNITY  397 

bovine  immunization.  Eepeated  injections  of  a  virus  induce  a  much 
higher  and  more  lasting  immunity  than  single  inoculations. 

(c)  By  the  Introduction  of  a  Bacterial  Vaccine. — The  immunity 
produced  by  the  introduction  of  a  vaccine  into  the  body  corresponds 
precisely  to  the  immunity  acquired  by  the  introduction  of  a  virus,  the 
only  difference  being  that  the  living  virus  produces  a  more  lasting  and 
higher  degree  of  protection  than  that  produced  by  the  dead  vaccine. 
The  advantages  of  using  a  vaccine  instead  of  a  virus  are  obvious. 

Dead  bacteria,  when  injected  into  the  tissues,  usually  produce  a  local 
reaction  at  the  site  of  inoculation  and  also  a  general  reaction.  The 
local  reaction  consists  of  swelling,  pain,  redness,  and  other  indications 
of  irritation  and  inflammation.  The  general  reaction  consists  of  fever, 
headache,  pains  in  the  muscles,  especially  in  the  back  and  legs,  malaise, 
and  sometimes  nausea.  The  reactions  usually  come  on  within  a  few 
hours  after  the  vaccine  has  been  introduced  and  rarely  last  longer  than 
2-i  to  48  hours.  It  is  customary  to  give  the  vaccines  in  the  evening,  for 
then  most  of  the  symptoms  have  passed  by  the  next  morning. 

The  vaccine  is  usually  prepared  from  a  fresh  twenty-four-hour  growth 
of  a  pure  culture  of  the  microorganism  upon  the  surface  of  agar.  In 
this  way  secondary  metabolic  products  in  the  medium  are  avoided  by 
simply  removing  the  surface  growth.  When  liquid  cultures  are  used 
the  foreign  substances  contained  in  the  medium  may  complicate  the  re- 
actions. The  cultures  are  usually  killed  by  exposure  to  heat  at  from  53° 
to  G0°  C.  for  one  hour.  High  heat,  while  certain  to  kill  the  virus,  is 
undesirable,  for  the  reason  that  it  coagulates  the  albuminous  substances 
in  the  germ  cell  and  otherwise  alters  the  chemical  structure  of  the  micro- 
organism. The  closer  the  vaccine  approaches  the  virus  the  better  the 
results,  so  far  as  immunity  is  concerned.  Therefore,  many  investigators 
prefer  to  kill  the  microorganisms  with  carbolic  acid,  chloroform,  or  some 
other  suitable  germicide. 

Sensitized  vaccines  are  made  by  mixing  the  bacteria  with  its  specific 
antibody  and  then  washing  away  the  excess  of  antibody.  If,  for  example, 
typhoid  bacilli  are  injected  into  a  rabbit,  antibodies  appear  in  the  blood 
serum  of  the  rabbit.  If  new  typhoid  bacilli  are  mixed  with  this  rabbit 
serum  (which  must  be  first  inactivated  by  heating),  the  bacilli  become 
sensitized.  In  other  words,  the  bacteria  unite  with  the  specific  antibodies 
present  in  the  rabbit's  serum.     Sensitized  bacilli  may  be  dead  or  alive. 

The  advantages  of  sensitized  vaccines  have  been  advocated  by  Bes- 
redka,  Calmette,  Salembini,  Gay  and  others. 

Polyvalent  vaccines. — Several  cultures  may  be  mixed  and  given  at 
the  same  time.  Thus,  a  tetravaccine,^  containing  typhoid,  paratyphoid 
A  and  B,  and  cholera,  was  used  in  Serbia. 

The  injections  are  always  given  subcutaneously.     Usually  three  or 

^Castellani  and  Mendelson,  Brit.  Med.  Journal,  Nov.  13,  1915. 


398  IMMUNITY 

four  injections  are  given  at  intervals  of  al)out  five  to  ten  days.  Several 
injections  produce  an  immunity  of  much  higher  grade  and  longer  dura- 
tion. In  most  instances  the  acquired  immunity  lasts  from  two  to  five 
years,  and  may  he  renewed. 

Preventive  inoculations  with  bacterial  vaccines  are  now  much  prac- 
ticed in  the  case  of  typhoid  fever,  plague,  and  cholera,  and  are  destined 
to  be  extended  to  other  infections.  The  dose  and  details  have  been 
discussed  under  each  disease. 

Standardization  of  Bacterial  Vaccines. — Bacterial  vaccine  may  be 
standardized  by  several  methods.^  Wright's  method  ^  consists  in  compar- 
ing the  number  of  bacteria  with  the  number  of  red  corpuscles  on  a 
stained  slide.  The  errors  in  this  method  are  numerous  and  may  vary 
from  50  per  cent,  to  100  per  cent,  if  counted  on  the  same  film  made  by 
different  observations. 

The  nephelometer  method  described  by  McFarland  ^  consists  in  com- 
paring the  opacity  of  the  culture  with  a  series  of  standardized  tubes 
containing  a  fine  precipitate.  This  method  is  a  fair  guess,  for  the 
errors  vary  from  25  per  cent,  to  200  per  cent. 

Wilson  and  Dickson  proceed  by  weighing  the  dried  culture  on  a  piece 
of  thin  platinum  foil.  The  method  has  not  been  used  on  account  of  the 
special  apparatus  necessary  for  its  application. 

The  plate-culture  method  consists  in  standardizing  the  suspension  by 
counting  the  colonies  which  develop.  The  defects  are  that  it  requires 
two  or  three  days  before  the  results  can  be  known ;  that  the  colonies  may 
represent  the  growth  of  more  than  one  bacteria;  and  some  of  the  bacteria 
may  not  grow.  The  plate  method  always  gives  low  counts  varying  from 
25  per  cent,  to  150  per  cent,  less  than  the  hemocytometer. 

The  gravimetric  method  employed  by  Hopkins  ^  consists  in  the  use  of 
a  special  centrifuge  tube,  the  end  of  which  is  drawn  out  into  a  small  tip. 
This  is  graduated  in  hundredths  of  a  cubic  centimeter.  The  amount  of 
centrifugalized  sediment  may  be  read  directly  upon  the  scale.  The- 
method  gives  but  approximate  results. 

Mallory  and  Wright  ^  first  used  the  hemocytometer  for  counting  the 
number  of  bacteria  in  a  suspension.  The  chamber  used  is  manufactured 
by  Zeiss  for  counting  blood  plates  by  the  Helber  method.  Some  method 
employing  the  hemocytometer  offers  the  most  accurate  technic  for 
standardizing  vaccines. 

Specificity. — Most  of  the  reactions  in  immunology  are  specific — not 

^  Fitch   (review),  J.  A.  M.  A.,  Mar.  13,  1915,  LXIV,   11,  p.  893. 

2  Wright,  A.  E. :  "On  Some  New  Procedures  for  the  Examination  of  the 
Blood  and  of  Bacterial  Cultures,"  Lancet,  London,  1901,  II,  11. 

« McFarland,  Joseph:     "The  Nephelometer,"  J.  A.  M.  A.,  Oct.  5,  1907,  p.  1176. 

*  Hopkins,  J.  G. :  "A  Method  for  Standardizing  Bacterial  Vaccines,"  J.  A. 
M.  A.,  May  24,   1913.  p.   1615. 

''Mallory  and  Wright:  "Pathological  Technic,"  Ed.  4,  Philadelphia,  W.  V.. 
Saunders  Company,  1910. 


IMMUNITY  399 

absolutely  so,  but  relatively;  that  is,  antibodies,  such  as  agglutinins, 
lysins,  precipitins,  or  opsonins,  usually  act  upon  the  corresponding  an- 
tigen with  much  greater  vigor  than  upon  any  other.  An  immunity  to 
one  disease,  no  matter  how  produced,  whether  natural  or  acquired,  af- 
fords no  protection  against  other  diseases.  There  is,  however,  no  abso- 
lute specificity,  just  as  there  is  no  absolute  immunity. 

Certain  microorganisms  and  their  toxic  products  show  a  remarkable 
predilection  for  certain  cells  or  tissues.  In  this  sense  a  microparasite 
or  a  toxin  may  be  as  specific  in  its  action  as  a  qualitative  chemical  re- 
action. Thus,  there  is  a  specific  relation  between  tetanus  toxin  and 
nervous  matter,  while  the  poison  has  little  or  no  affinity  for  other  tis- 
sues. The  poison  of  infantile  paralysis  picks  out  certain  cells  in  the 
central  nervous  system  upon  which  it  acts  specifically.  Also  in  rabies 
the  brunt  of  the  lesions  falls  upon  the  cells  of  the  central  nervous  sys- 
tem. The  toxic  products  of  the  Bacillus  hotulismus  is  also  a  specific 
nerve  poison,  and  at  least  one  of  the  poisons  in  diphtheria  toxin  (toxon) 
acts  specifically  upon  the  nerves.  The  toxic  substances  may  also  react 
upon  less  important  or  indifferent  tissues,  but  such  action  is  often 
masked.  The  specific  action  of  toxins  explains  in  part  the  local  immu- 
nity enjoyed  by  some  tissues  and  further  explains  why  certain  viruses 
are  comparatively  harmless  when  introduced  into  the  body  through 
unaccustomed  channels.  We  have  already  seen  an  example  of  this  in 
a  case  of  cholera  when  introduced  into  the  subcutaneous  tissue.  In 
this  case  the  subcutaneous  tissue  is  resistant  to  the  invasion  of  the 
cholera  vibrio,  and  these  microorganisms  cannot  find  their  way  to  the 
intestinal  tract.  The  case  of  smallpox  is  instructive,  for  this  is  an  in- 
fection for  which  the  epithelial  structures  have  a  specific  susceptibility. 
It  is  practically  impossible  to  infect  a  susceptible  animal  with  cowpox 
when  the  virus  is  introduced  subcutaneously  or  directly  into  the  cir- 
culation. The  same  is  probably  true  of  smallpox.  When  smallpox 
virus  is  introduced  by  inoculation  upon  the  skin  the  disease  is  much 
milder  than  when  the  virus  is  introduced  naturally  by  way  of  the  respira- 
tory tract.  Evidently  the  skin  offers  greater  resistance  to  the  smallpox 
virus  than  is  offered  by  the  mucous  membranes.  On  the  other  hand, 
foot-and-mouth  disease  cannot  be  given  to  man  or  the  cow  when  rubbed 
upon  the  skin,  although  these  animals  are  very  susceptible  when  this 
virus  is  introduced  into  the  general  circulation  or  rubbed  upon  the  mu- 
cous membrane  of  the  mouth.  Every  worker  in  a  bacteriological  labora- 
tory is  familiar  with  the  difference  in  susceptibility  of  different  tis- 
sues and  knows  the  importance  in  experimental  work  of  bringing  the 
virus  in  association  with  appropriate  structures. 

Certain  microorganisms,  such  as  tuberculosis,  pus  cocci,  the  pneumo- 
coccus,  etc.,  have  the  power  of  affecting  almost  every  tissue  and  organ 
of  the  body.     ISTo  part  of  the  body  is  immune  to  the  tubercle  bacillus, 


400  .  IMMUNITY 

but  even  in  tin's  infection  fiome  tissues  are  more  susceptible  than  others. 
Thus,  tuberculosis  of  the  muscle  is  extremely  rare;  the  lungs  and  lymph 
nodes  are  especially  vulnerable. 

The  stomach  is  comparatively  rarely  attacked  by  infei-tive  processes, 
although  constantly  exposed.  The  vaginal  mucous  membrane  in  the 
adult  and  the  bladder  are  resistant  to  gonorrheal  inflammations.  There 
are  many  similar  instances  of  specific  resistance  of  tissues. 

The  specific  action  of  toxins  gives  us  a  ready  reason  why  certain 
species  of  animals  are  immune  to  certain  infections.  In  this  case 
the  immunity  is  not  the  result  of  any  special  or  specific  reaction,  nor, 
is  it  the  result  of  any  positive  character  possessed  or  acquired  by  the 
body,  but  is  a  negative  trait  entirely,  due  to  the  absence  of  specific 
chemical  affinity  between  the  cells  and  the  toxin.  The  turtle  is  im- 
mune to  tetanus  because  there  is  no  combining  affinity  between  the  nerve 
cells  of  the  turtle  and  tetanus  toxin.  The  immunity,  therefore,  depends 
upon  the  absence  of  the  appropriate  cell  receptors.  Eats  are  highly 
immune  to  diphtheria  toxin  and  hogs  to  snake  venom.  In  these  cases 
antitoxin  cannot  be  demonstrated  in  the  blood  of  the  rat  or  the  hog, 
and,  so  far  as  can  be  determined,  when  the  toxin  is  injected  into  these 
animals  it  is  not  neutralized  in  the  body.  The  simplest  conception  of 
the  mechanism  of  immunity  in  these  cases  is  to  regard  it  as  depending 
upon  a  negative  factor  resulting  upon  the  absence  of  suitable  receptors 
in  the  sense  of  Ehrlich's  side-chain  theory. 

Local  and  General  Immunity. — Local  and  general  immunity  depends 
upon  this  variation  in  susceptibility  of  the  different  tissues  to  differ- 
ent infections.  It  is  doubtful  if  there  is  a  true  general  immunity 
in  any  case,  for  a  general  immunity  is  in  almost  all  instances  based 
upon  a  local  resistance.  Even  antitoxic  immunity  in  diphtheria, 
due  to  the  antibodies  in  the  general  circulating  blood,  is  the  result 
of  a  localized  neutralization  in  which  many  of  the  organs  and  tissues 
of  the  body  take  no  part.  There  are  many  examples  of  local  immunity. 
Trichinella  spiralis  affects  especially  the  striped  muscles  and  never 
the  bones.  Diphtheria  seldom  extends  down  the  esophagus.  The  most 
marked  example,  perhaps,  is  the  almost  perfect  local  immunity  of  the 
scalp  to  ringworm  in  adults,  which  contrasts  so  markedly  with  the  ab- 
solute susceptibility  of  children,  whereas  the  susceptibility  of  the  skin 
of  the  body  to  the  same  parasite  is,  if  anything,  greater  in  adults  than 
in  children  (Emery). 

Many  remarkable  instances  of  local  immunity  are  shown  by  the  tis- 
sues and  must  be  familiar  to  all.  Thus,  erysipelas  does  not,  as  a  rule, 
extend  into  the  subcutaneous  tissues,  although  the  streptococcus  may  be 
there;  rarely  does  it  extend  back  into  the  area  of  the  skin  recently 
affected. 

The  immunity  of  a  part  is  increased  or  diminished  by  the  presence 


IMMUNITY  401 

or  absence  of  an  adequate  blood  supply.  As  a  rule,  very  vascular  struc- 
tures enjoy  a  comparative  immunity  to  infections  which  frequently 
attack  other  tissues  relatively  poor  in  blood  supply.  It  may  be  stated 
as  a  general  rule  that  the  more  copious  the  supply  of  healthy  circulat- 
ing blood  the  greater  the  resistance  to  infection,  and  vice  versa.  This 
largely  accounts  for  the  local  immunity  enjoyed  by  the  mucous  mem- 
brane of  the  mouth  and  lips,  which  are  constantly  exposed  to  wound 
infections.  Herein  we  also  have  an  explanation  of  the  utility  of  fo- 
mentations and  other  hot  applications  in  the  initial  stages  of  an  in- 
fective lesion.  The  same  explanation  is  applied  in  Bier's  method  of 
passive  congestion,  in  which  an  excess  of  blood  is  made  to  flush  the 
tissues.  The  local  immunity  of  the  part  may  be  diminished  by  a  local 
anemia  from  any  cause,  by  the  presence  of  dead  or  injured  tissue,  by 
the  action  of  irritants,  trauma,  etc. 

Metchnikoff  has  pointed  out  that  in  many  infections  general  pro- 
tection is  in  inverse  ratio  to  the  local  reaction  at  the  site  of  introduc- 
tion of  the  virus.  A  severe  and  prompt  local  inflammatory  reaction 
indicates  an  active  power  of  protection.  The  increased  volume  of  blood, 
the  cells,  the  fluids  of  the  blood  and  tissues  are  concentrated  about  the 
invading  bacteria  to  wall  them  off  and  destroy  them,  that  is  the  im- 
munity of  the  body  against  a  general  infection  frequently  depends  upon 
the  promptness  and  the  activity  of  the  local  power  of  reaction. 

Some  infections,  notably  streptococci,  plague,  or  organisms  belong- 
ing to  the  hemorrhagic-septicemic  group,  may  invade  the  body  with 
little  or  no  local  inflammatory  reaction;  that  is,  little  or  no  barrier  is 
set  up  against  these  microorganisms,  they  may  invade  the  blood  and 
tissues  without  resistance  and  thus  cause  fatal  septicemias. 

Bacillus  Cairiers  or  Immunitas  Non  Sterilans. — Upon  recovery  from 
an  infective  process  the  body  usually  rids  itself  completely  of  the  infecting 
agent.  In  other  words,  the  immunity  which  follows  an  attack  of  an 
infectious  disease  is  usually  associated  with  a  power  the  body  has  of  dis- 
infecting itself.  In  most  cases  the  patient  is  convalescent  or  completely 
restored  to  health  before  the  cause  of  the  disease  has  disappeared  from 
the  tissues.  This  bespeaks  a  vigorous  protecting  mechanism,  but  when 
this  resistance  is  lowered  for  any  reason  a  relapse  may  ensue. 

In  many  instances  recovery  takes  place,  but  the  living  virulent 
microorganisms  continue  to  live  in  the  body.  This  constitutes  immu- 
nity without  sterilization,  a  term  introduced  by  Ehrlich,  though  a 
more  precise  expression  would  be  "immunity  without  disinfection.'' 
Such  persons  are  now  known  as  "bacillus  carriers."  The  immunity  pro- 
tects the  carrier  but  endangers  his  fellowmen.  Bacillus  carrying  is 
common  in  diphtheria,  typhoid  fever,  cholera,  pneumonia,  epidemic 
cerebrospinal  meningitis,  influenza,  and  many  other  bacterial  infec- 
tions.    Protozoon  carriers  are  also  a  common  phenomenon.     The  best 


403  IMMUNITY 

examples  are  found  in  malaria,  trypanosomiasis,  ''i'exas  fever  in  cattle, 
etc.  Analogous  instances  are  also  found  in  the  higher  parasitic  worms 
in  which  the  individual  who  carries  the  parasite  is  not  affected.  Thus, 
the  negro  and  the  Filipino  show  a  relatively  high  degree  of  immunity 
to  the  hookworm  and  thus  endanger  their  more  susceptible  white  com- 
panion. 

Bacillus  carriers  play  an  important  role  in  spreading  iijfections. 
They  explain  many  mysterious  facts  in  the  epidemiology  of  dijjhtberia, 
typhoid  fever,  cholera,  cerebrospinal  meningitis,  malaria,  etc.  The 
bacillus  carrier  is  sometimes  a  danger  to  himself.  This  is  seen  in  diph- 
theria, pneumonia,  influenza,  and  sometimes  in   typhoid  and   cholera. 

While  it  is  undoubtedly  true  that  bacillus  carriers  play  a  very  im- 
portant role  in  spreading  infection  from  man  to  man,  the  relative  im- 
portance compared  with  other  modes  of  transmission  cannot  be  stated 
in  percentage.  The  subject  is  still  too  young  for  definite  quantitative 
figures.  There  is  no  doubt  that  bacillus  carriers  are  more  important 
in  some  diseases  than  others  and  play  a  variable  role  under  different 
circumstances  in  the  same  disease.  In  our  studies  of  typhoid  fever 
in  Washington  one  carrier  was  discovered  in  the  examination  of  986 
healthy  individuals.  This  would  mean  approximately  300  typhoid 
bacillus  carriers  in  the  District  of  Columbia.  If  this  proportion  is  cor- 
rect, it  would  account  for  the  endemicity  of  typhoid  fever  in  Washing- 
ton. Perhaps  the  residual  typhoid  fever  in  many  places  is  largely  kept 
alive  through  bacillus  carrying.  Great  sanitary  reforms,  such  as  the 
change  from  polluted  to  pure  water,  causes  both  a  decline  in  the  amount 
of  the  fever  and  a  decrease  in  the  number  of  carriers.  It  now  seems 
evident  that  polluted  water  and  infected  milk  will  not  always  cause  the 
disease  directly  in  the  persons  drinking  these  fluids,  but  may  produce 
carriers  who  either  contract  the  disease  themselves  subsequently  or  give 
it  to  others  by  passing  the  virus  on  in  a  more  concentrated  and  virulent 
form,  or  to  more  susceptible  individuals. 

It  is  evident  from  the  nature  of  the  case  that  the  cure  and  control 
of  bacillus  carriers  is  one  of  the  vital  problems  in  preventive  medicine. 
It  is  not  only  largely  through  them  that  infection  is  spread,  but  the 
infections  themselves  are  kept  alive  in  these  carriers,  who  bridge  over 
the  interval  between  outbreaks.  It  is  qiiite  conceivable  that  with  our 
modern  methods  of  isolation  and  disinfection  certain  diseases  would  soon 
cease  to  exist  were  it  not  for  immunitas  non  sterilans. 

Immunity  is,  therefore,  a  double-edged  sword,  in  that  it  protects  the 
carrier  but  endangers  his  neighbor.  The  control  of  bacillus  carriers  is 
a  difficult  problem.  Siich  unfortunate  persons  cannot  always  be  im- 
prisoned, nor  is  strict  isolation  always  necessary.  It  is  sufficient  in  the 
case  of  typhoid  fever  to  restrict  the  activity  of  the  carrier.  Thus,  a 
typhoid  carrier  should  not  cook,  prepare,  or  handle  food,  or  have  any- 


IMMUNITY  403 

thing  to  do  with  the  production  or  distribution  of  milk.  We  have  no 
satisfactory  cure  for  carriers ;  this  is  a  problem  for  the  future ;  but 
their  numljer  may  be  lessened — this  is  a  problem  for  the  present. 

It  should  always  be  remembered  that  the  number  of  carriers  will 
diminish  proportionately  with  the  number  of  cases  of  any  infection, 
and  that  every  improvement  in  the  water  supply,  the  milk  supply,  the 
food  supply,  and  our  sanitary  conditions  generally  will  have  a  tendency 
to  sharply  diminish  the  number  of  carriers  in  any  given  infection. 
Therefore,  while  isolation,  disinfection,  and  other  methods  used  to 
control  the  spread  of  infection  will  never  be  completely  successful  as 
long  as  the  carrier  is  omitted,  nevertheless,  these  methods  are  entirely 
justified  even  though  only  partially  useful.  It  is  the  duty  of  public 
health  officers  to  check  the  spread  of  infection  wherever  it  may  be 
found.  In  time  ready  methods  of  recognizing  bacillus  carriers  and 
means  of  neutralizing  their  potential  danger  will  be  more  effective 
than  is  now  possible. 

Latency  is  closely  allied  to  bacillus  carrying.  The  malarial  parasite 
may  remain  latent  in  the  spleen  and  other  internal  organs  for  years, 
during  which  time  the  person  remains  in  good  health.  But  when  the 
resistance  is  reduced  by  exposure,  fatigue,  starvation,  or  other  depressing 
influences  the  disease  again  breaks  out.  The  gonococcus  may  also  remain 
latent  for  years.  I  am  familiar  wath  one  instance  in  which  the  tubercle 
bacillus  remained  latent  in  the  axillary  glands  for  10  years  and  then 
became  active  owing  to  a  condition  of  depressed  vitality.  Typhoid  ostitis 
may  develop  years  after  an  attack  of  typhoid  fever,  and  we  can  only 
assume  that  the  bacilli  have  remained  latent  in  the  tissues  all  that  time. 
The  phenomenon  of  latency  also  occurs  in  rabies,  tetanus,  and  other 
infections. 

Lowered  Resistance. — The  factors  which  lower  our  general  resist- 
ance to  disease  are  many  and  varied.  The  condition  known  as  depressed 
vitality,  lowered  tone,  general  debility,  weakened  constitution,  and  terms 
of  similar  import  imply  a  condition  in  which  immunity  is  lowered  in  a 
general  and  not  in  a  specific  sense.  The  principal  causes  which  diminish 
resistance  to  infection  are :  wet  and  cold,  fatigue,  insufficient  or  unsuit- 
able food,  vitiated  atmosphere,  insufficient  sleep  and  rest,  worry,  and 
excesses  of  all  kinds.  The  mechanism  by  which  these  varying  conditions 
lower  our  immunity  must  receive  our  attention,  for  they  are  of  the 
greatest  importance  in  preventive  medicine.  It  is  a  matter  of  common 
observation  that  exposure  to  wet  and  cold  or  sudden  changes  of  tempera- 
ture, overwork,  worry,  stale  air,  poor  food,  etc.,  make  us  more  liable  to 
contract  certain  diseases.  The  tuberculosis  propaganda  that  has  been 
spread  broadcast  with  such  energy  and  good  effect  has  taught  the  value 
of  fresh  air  and  sunshine,  good  food,  and  rest  in  increasing  our  resistance 
to  this  infection. 


404  IMMUNITY 

There  is,  however,  a  wrong  impression  abroad  that,  because  a  low- 
ering of  the  general  vitality  favors  certain  diseases,  such  as  tuberculosis, 
common  colds,  pneumonia,  septic  and  other  infections,  it  plays  a  similar 
role  in  all  the  communicable  diseases.  Many  infections,  such  as  smallpox, 
measles,  yellow  fever,  tetanus,  whooping-cough,  typhoid  fever,  cholera, 
plague,  scarlet  fever,  and  other  diseases,  have  no  particular  relation 
whatever  to  bodily  vigor.  These  diseases  often  strike  down  the  young 
and  vigorous  in  the  prime  of  life.  The  most  robust  will  succumb  quickly 
to  tuberculosis  if  he  receives  a  sufficient  dose  of  the  virulent  microorgan- 
isms. A  good  physical  condition  does  not  always  temper  the  virulence  of 
the  disease;  on  the  contrary,  many  infections  run  a  particularly  severe 
course  in  strong  and  healthy  subjects,  and,  contrariwise,  may  be  mild  and 
benign  in  the  feeble.  Physical  weakness,  therefore,  is  not  necessarily 
synonymous  with  increased  susceptibility  to  all  infections,  although  true 
for  some  of  them.  In  other  words,  "general  debility"  lowers  resistance  in 
a  specific,  rather  than  in  a  general,  sense. 

The  mechanism  by  which  the  various  causes  that  lower  vitality  and 
increase  susceptibility  act  is  in  most  cases  quite  obscure.  Here  is  a  field 
for  laboratory  research  in  immunology  that  offers  rich  reward  of  im- 
measurable practical  good.  Some  of  the  factors  concerned  will  be  briefly 
discussed. 

Exposure  to  wet  and  cold,  especially  in  combination,  is  a  frequent 
source  of  lowered  resistance.  The  exact  way  in  which  such  exposure 
acts  is  not  definitely  known,  but  laboratory  researches  offer  material 
for  a  number  of  suggestions.  Emery  ^  sums  up  our  knowledge  upon 
this  subject  as  follows : 

"Immunity  is  to  a  very  large  extent  a  function  of  the  leukocytes, 
which  are  specialized  cells  to  which  the  defense  of  the  body  is  entrusted. 
Now,  the  functions  (movement  and  phagocytosis)  Avhich  can  be  easily 
investigated  are  found  to  be  dependent  in  a  very  high  degree  on  tem- 
perature, acting  best  at  the  temperature  of  the  body,  or  slightly  above; 
and  it  is  highly  probable  that  the  more  subtle  functions  of  the  leuko- 
cytes may  be  similarly  depressed  by  a  low  temperature.  The  exposure 
of  the  skin  to  cold,  especially  if  the  animal  heat  be  abstracted  more 
quickly  by  evaporation  of  moisture  on  the  surface,  will  lead  to  a  cool- 
ing of  the  blood  which  circulates  through  it,  and  hence  to  a  slight, 
though  appreciable,  cooling  of  the  whole  blood.  This,  it  is  true,  is 
soon  compensated  for,  and  no  great  amount  of  cooling  of  the  whole  body 
occurs;  but,  even  so,  it  is  quite  possible  that  the  periodical  chilling  of 
the  leukocytes  during  their  repeated  passages  through  the  cold  skin 
may  be  sufficient  to  diminish  greatly  their  functional  activity,  and  to 
lower  the  resistance  to  a  point  at  which  infection  may  occur,  and  when 
once  pathogenic  bacteria  have  gained  a  foothold  the  resistance  will  for 

*  "Immunity  and  Specific  Therapy,"  1909,  p.  9. 


IMMUNITY  405 

a  time  tend  to  decrease.  There  is  also  some  evidence  going  to  show 
that  exposure  to  cold  may  lessen  the  production  of  the  defensive  sub- 
stances which  occur  in  the  blood  (alexin,  antibodies,  etc.),  though  this 
is  not  fully  proved.  It  is  worthy  of  note  that  the  loss  of  immunity  due 
to  the  action  of  cold  and  wet  on  one  part  of  the  body  (such  as  the 
feet)  is  a  general  one,  and  may  result  in  a  nasal  catarrh,  an  attack  of 
pneumonia,  acute  rheumatism,  etc.,  according  to  the  nature  of  the  in- 
fection at  hand.  It  is  not  necessarily  a,  local  infection  of  the  chilled 
region.  This  is  very  well  shown  experimentally.  Fowls  are  immune 
to  anthrax,  but  are  rendered  susceptible  if  they  are  kept  for  some  time 
standing  in  cold  water;  and  this  acquired  susceptibility  is  then  a  gen- 
eral one,  and  not  merely  of  the  feet. 

"Cold  and  wet,  as  is  well  known,  have  less  action  when  accompanied 
by  energetic  muscular  exercise,  so  long  as  this  does  not  reach  the  ex- 
tent of  undue  fatigue.  This  is  not  because  less  heat  is  lost  during 
exercise.  The  reverse  is  the  case.  The  suggested  explanation  is  that 
the  muscular  metabolism  leads  to  an  increased  production  of  heat,  and 
at  the  same  time  the  cutaneous  capillaries  are  dilated  and  the  heart 
accelerated,  or  that  the  circulation  of  blood  through  the  skin  occurs 
quickly;  further,  the  internal  temperature  of  the  body  may  actually  be 
raised  several  degrees.  The  result  is  that  the  temperature  of  any  given 
leukocyte  never  falls  much  below  normal,  if  at  all,  since  it  comes  from 
the  internal  regions  where  the  temperature  is  raised,  passes  rapidly 
through  the  skin,  and  returns  again  to  the  interior  of  the  body. 

"The  effect  of  fatigue,  either  alone  or  in  conjunction  with  cold  and 
wet,  is  also  well  known,  and  is  one  reason  for  the  excessive  mortality 
from  disease  of  armies  in  the  field.  It  is  less  explicable,  but  may  prob- 
ably be  connected  in  some  way  with  the  presence  in  the  blood  of  kata- 
bolic  products  of  muscular  activity,  which  have  an  injurious  action  on 
the  cells  of  the  tissues  in  general  and  on  the  leukocytes  in  particular. 
Further,  the  metabolic  products  formed  during  the  action  of  the  muscles 
are  acid  in  reaction,  and  it  is  found  that  some  at  least  of  the  protective 
substances  which  occur  in  the  blood  (alexins  and  opsonins)  act  best 
in  alkalin  medium.  This  diminution  of  immunity  after  muscular 
fatigue  is  manifested  in  animals  as  well  as  in  man.  White  rats  which 
have  been  made  to  work  in  a  revolving  cage  are  more  susceptible  to 
anthrax  than  normal  white  rats,  the  preexisting  immunity  being  broken 
down." 

De  Sandro  ^  "injected  dogs,  rabbits,  guinea-pigs,  with  typhoid  toxins 
after  severe  muscular  strain.  Under  the  influence  of  the  chemical 
changes  induced  by  the  physical  strain,  the  nervous  exhaustion,  fatigue 
of  the  heart,  and  disturbances  in  the  blood  production,  the  defensive 
powers  were  evidently  much  weakened;  phagocytosis  was  reduced  and 

^  Riforma  Medica,  Naples,  Aug.  1  &  8,  Nos.  31  &  32. 


406  IMMUNITY 

also  the  chemotaetic  power  of  the  cells,  the  bactoriolysiiis,  antitoxins, 
agglutinins,  and  opsonins  showed  a  marked  falling  oil." 

Insufficient  and  unsuitable  food  is  a  prime  factor  iji  undermining 
vitality  and  lowering  resistance.  The  infliience  upon  health  of  food 
poor  in  quality  or  lacking  in  quantity  is  a  matter  of  common  experi- 
ence, but  the  scientific  explanation  of  the  way  in  which  this  result  is 
brought  about  is  not  at  all  clear.  First  of  all,  it  must  be  remembered 
that  starvation  or  improper  food  does  not  depress  immunity  to  all 
infections,  but  lowers  resistance  only  to  certain  infections.  It  was  for- 
merly supposed  that  famine  was  the  direct  cause  of  pestilence.  In 
fact,  in  India  it  has  commonly  been  stated  that  '^plague  follows  famine 
with  some  regularity,"  but  we  know  now  that  plague  in  man  is  second- 
ary to  the  disease  in  rats  and  is  transmitted  through  the  flea.  Ee- 
lapsing  fever  was  formerly  called  famine  fever,  and  outbreaks  of  typhus 
fever  were  frequently  connected  with  famine,  but  we  know  now  that  the 
former  is  transmitted  by  the  tick  and  the  latter  by  the  louse.  It  is 
evident  that  famine  may  be  indirectly  a  cause  of  epidemic  outbursts 
without  necessarily  depressing  immunity.  Famine  is  usually  accom- 
panied by  misery  and  squalor  and  an  increase  of  vermin  and  other 
factors  that  favor  the  transmission  of  disease. 

Tuberculosis,  of  all  diseases,  is  favored  by  insufficient  and  unsuit- 
able food.  This  is  an  infection  in  which  poor  nourishment  lowers, 
and  good  nourishment  raises,  our  resistance.  Poor  and  insufficient  food, 
however,  is  usually  associated  with  poverty,  insufficient  clothing,  un- 
cleanly habits,  vitiated  atmosphere,  overwork,  insufficient  rest,  and  other 
depressing  influences,  so  that  it  is  difficult  to  assign  relative  importance 
to  any  one  of  these  factors.  For  this  reason  we  may  perhaps  be  led  to 
exaggerate  its  importance;  and,  while  it  is,  of  course,  true  that  semi- 
starvation,  in  common  with  other  weakening  influences,  does  pave  the 
way  for  infective  processes,  we  do  not  find  that  a  supply  of  food  restricted 
enough  to  cause  a  marked  reduction  of  the  bodily  strength  and  some 
degree  of  anemia  is  necessarily  associated  with  any  infective  disease, 
though  the  patient  may  live  under  conditions  in  which  infective  material 
is  present  in  abundance.  This  is  well  seen  in  fasting  men,  in  hysterical 
anorexia,  and  in  patients  with  impermeable  esophageal  strictures.  The 
blood,  it  may  be  pointed  out,  is  not  one  of  the  tissues  that  sufl^ers  first  in 
starvation,  and  its  importance  to  the  body  in  many  ways  is  so  great  that 
it  is  kept  in  good  functional  activity  while  other  tissues  waste  quickly.^ 

There  is  a  general  belief  that  exposure  to  infection  is  less  dangerous 
after  a  meal  than  upon  an  empty  stomach.  There  is  little  ground  for 
this  belief,  unless  we  take  into  consideration  the  notable  increase  in  the 
number  of  leukocytes  in  the  peripheral  blood  during  active  digestion. 
It  was  recognized  long  ago  that  wounds  inflicted  during  autopsies  are 

*  Unbalanced  diets  lead  directly  to  scurvy,  beriberi,  or  pellagra  (page  522). 


IMMUNITY  407 

much  more  dangerous  when  received  while  fasting  than  during  the 
process  of  digestion,  and  it  is  possible  that  this  may  be  due  to  some 
extent  to  the  increased  number  of  leukocytes  which  occur  in  the  periph- 
eral blood  during  digestion.  Further,  infection  reaching  an  empty 
stomach  has  greater  chances  of  passing  into  the  small  intestines  than 
if  it  reaches  the  stomach  after  a  full  meal  when  acidity,  time,  and  the 
digestive  enzymes  have  a  chance  to  destroy  the  microorganisms.  This 
may  be  of  importance  in  cholera,  typhoid,  dysentery,  and  other  intestinal 
infections. 

Exposure  to  a  vitiated  atmospliere,  if  of  long  duration,  is  one  of 
the  potent  causes  of  breaking  down  resistance.  Here  again,  however, 
immunity  is  lowered  in  a  specific  and  not  in  a  general  sense.  Thus, 
vitiated  air  renders  the  individual  more  susceptible  to  tuberculosis, 
pneumonia,  common  colds,  and  other  acute  respiratory  affections.  On 
the  other  hand,  it  can  have  little  influence  in  determining  the  infec- 
tion of  most  of  the  communicable  diseases,  although  the  lowered  tone 
of  the  body  caused  by  vitiated  air  may  influence  the  severity  of  the 
attack.  The  mechanism  by  which  vitiated  air  increases  susceptibility 
is  not  understood.     The  subject  is  discussed  in  Chapter  lY  upon  Air. 

Excesses  of  all  kinds,  symbolized  by  Bacchus,  Venus,  and  A^ulcan, 
are  mighty  factors  in  lowering  vitality  and  in  increasing  susceptibility 
to  certain  diseases.  In  this  category  are  also  found  worry,  overwork, 
loss  of  sleep,  and  fatigue. 

Certain  drugSj  of  which  the  most  important  is  alcohol,  have  an  im- 
portant action  in  lowering  resistance.  Emery  states  that :  "The  liability 
of  alcoholic  svibjects  to  pneumonia  and  some  other  infective  diseases  is 
well  known,  and  in  them  the  prognosis  is  more  than  usually  unfavorable. 
We  have  but  little  knowledge  of  the  action  of  alcohol  in  this  respect. 
It  may  be  that  it  acts  as  a  direct  inhibitant  of  the  activity  of  the 
leukocytes,  and  it  is  known  to  destroy  certain  delicate  defensive  sub- 
stances (alexins  and  opsonins)  which  play  some  part  in  the  defense  of 
the  body  against  microbic  invasion,  but  it  is  not  known  whether  these 
effects  are  actually  manifested  in  the  circulating  blood.  It  is  also  pos- 
sible that  alcohol  tends  to  inhibit  the  formation  of  these  defensive  sub- 
stances. 

"Alcohol  tends  to  lower  the  temperature  of  the  body  by  increasing 
the  amount  of  heat  lost.  It  dilates  the  superficial  vessels  and  accelerates 
the  heart  action  in  a  way  somewhat  similar  to  muscular  exercise,  but 
does  not,  like  it,  raise  the  temperature  of  the  interior  of  the  body. 
Hence  the  effect  of  alcohol  in  conjunction  with  cold  and  wet  is  to  in- 
crease their  ill  effects.  More  blood  is  forced  through  the  chilled  skin 
and  more  heat  is  lost.  The  injurious  effect  of  alcohol  during  exposure 
to  cold  is  well  known." 

Relation  Between  Host  and  Parasite. — The  story  of  the  infectious 


408  IMMUNITY 

diseases  is  that  of  a  conjflict  between  two  beings:  one  the  host,  and  the 
other  the  parasite.  In  one  sense  this  conflict,  though  less  obvious,  is 
not  essentially  different  from  the  conflict  between  a  rattlesnake  and  his 
prey.  The  battle  between  host  and  parasite  results  in  a  reaction  in  the 
host,  and  this  reaction  we  call  the  disease.  The  various  elements  which 
make  up  this  conflict,  such  as  the  mode  of  attack  of  the  parasite  and 
the  means  of  defense  of  the  host,  are  being  carefully  studied.  An  active 
defense  on  the  part  of  the  host  will  sharpen  the  claws  of  the  parasite 
in  accordance  with  the  laws  of  the  survival  of  the  fittest,  and  thus 
increase  the  reaction,  i.  e.  the  intensity,  of  the  disease.  If  the  parasite  is 
unduly  aggressive  and  virulent,  and  thus  kills  its  host  too  quickly,  it 
defeats  its  own  object,  for  the  parasite  is  in  the  position  of  the  rats  on  a 
ship.  It  serves  small  purpose  to  scuttle  the  ship  unless  there  is  some 
means  of  passing  to  another  ship.  The  mode  of  transference  of  the 
parasite  is,  therefore,  of  vital  importance  to  the  parasite,  and  of  great 
practical  concern  to  the  host.  The  infectious  diseases,  then,  represent 
only  one  phase  in  a  complex  series  of  events  in  which  parasite  and  host  are 
interrelated  in  ways  often  and  justly  compared  to  seed  and  soil. 

The  invasion  of  the  parasite  and  the  reaction  which  occurs  in  the 
host  may  be  understood  by  comparing  an  individual  with  a  nation. 
A  nation  at  peace  with  the  world  and  in  a  state  of  healthy  progress, 
corresponds  to  an  individual  in  health.  Suppose  our  nation  is  visited 
by  an  alien  people,  say  the  inhabitants  of  Mars,  whom  we  will  take  to 
represent  the  parasite.  They  come  few  in  numbers,  are  looked  upon 
askance,  but  being  an  unknown  factor  no  special  measures  are  taken 
against  them;  meanwhile  they  grow  and  multiply.  This  is  the  period 
of  incubation.  In  time  they  become  numerous  enough  to  threaten  our 
homes  and  happiness.  Then  there  is  an  uprising  or  warfare.  The 
disease  begins,  it  is  a  fight  for  who  shall  have  possession  of  the  land,  that 
is,  the  host.  If  our  enemies  conquer,  the  disease  has  had  a  fatal  termina- 
tion, but  if  we  conquer,  and  kill  or  drive  off  our  enemies,  complete  re- 
covery takes  place.  If  a  few  of  the  enemy  remain,  we  are  in  the  con- 
dition of  a  bacillus  carrier,  subject  not  only  to  reinfecting  ourselves,  but 
endangering  the  peace  and  safety  of  the  neighboring  nations.  After  the 
battle  has  been  fought  and  won  it  leaves  us  immune,  in  other  terms, 
educated,  for  if  this  same  strange  race  should  again  come  to  our  shores 
they  would  at  once  be  met  with  an  immediate  reaction  and  not  allowed  to 
enter  our  fair  land. 

Ehrlich's   Side-chain  Theory   of  Immunity. — Ehrlich's  ^   side-chain 

^  Ehrlich :  "Die  Wertbemessung  des  Diphtherieheilserums  und  deren  theo- 
retische  Grundlagen."     Elin.  Jahrb.,  Jena,  VI   (2),  1897,  pp.  299-326. 

"Ueber  die  Constitution  des  Diphtheriegiftes."  Deut.  med.  Woch.,  Leip- 
zig, XXIV   (38),  1898,  pp.  597-600. 

Croonian  lecture.     "On  Immunity  with  Special  Reference  to  Cell  Life." 

Froc.  Roy.  Soc,  London,  LXVI,  pp.  424-448,  pis.  6-7. 


IMMUNITY  409 

theory  is  a  brilliajit  chemical  conception,  giving  the  only  satisfactory 
explanation  we  have  of  some  of  the  phenomena  concerned  in  immii- 
nity.  In  one  sense  it  has  been  likened  to  Weigert's  teachings  of  in- 
flammation and  the  process  of  repair  in  so  far  that  cognizance  is  taken 
of  nature's  prodigality.  For  instance,  a  much  larger  amount  of  ma- 
terial is  thrown  out  than  necessary  to  repair  a  wound.  So,  too,  in  an- 
titoxic immunity  a  much  larger  amount  of  antitoxin  is  produced  than 
necessary  to  neutralize  the  toxin. 

In  Ehrlich's  conception  the  fundamental  processes  of  immunity  re- 
side in  the  cells  of  the  body.  These  cells  are  attacked  by  the  poison, 
and  if  not  destroyed  are  stimulated  to  an  overproduction  of  "anti- 
bodies" capable  of  combining  with  and  neutralizing  the  poison. 

Just  what  cells  of  the  body  play  the  most  important  role  in  the 
production  of  this  form  of  immunity  is  not  exactly  clear.  It  may  be, 
as  Ehrlich  supposes,  that  this  power  resides  in  any  organ  or  tissue. 

According  to  Ehrlich,  the  hungry  protoplasm  of  any  cell,  with  its 
complicated  molecule,  having  side  chains  of  various  combining  affin- 
ities ready  to  unite  with  suitable  food  molecules  brought  to  it  by  the 
blood  and  body  juices,  lies  at  the  foundation  of  his  explanation  of  the 
chemical  production  of  the  antitoxin.  It  is  strange  that  the  same  com- 
bining affinity  should  exist  between  the  protoplasm  of  the  cell  and  the 
proteid  molecules  that  furnish  it  food,  as  between  the  cell  protoplasm 
and  the  toxins  of  the  bacterial  poisons. 

In  considering  Ehrlich's  ^  side-chain  theory  it  is  necessary  to  dis- 
regard the  microscopic  structure  of  the  cell  and  to  think  of  the  proto- 
plasm as  consisting  of  living  molecules  of  extraordinary  chemical  com- 
plexity. The  molecule  of  protoplasm  has  a  central  "nucleus"  with 
"side  chains,"  "lateral  chains,"  or  "bonds"  of  varying  combining  ca- 
pacities. These  "side  chains"  serve  to  bind  the  molecule  to  other  mole- 
cules having  proper  combining  affinities. 

This  arrangement  of  molecules  with  side  chains  is  a  well-known 
occurrence  in  organic  compounds.  The  benzol  ring  forms  one  of  the 
best  and  simplest  examples. 

H  (OH)  (OH) 

C  C  C 

/x  /x  /x 

HC       CH  HC       CH  HC       C  (OH) 

I        II  '  I        II  I        II 

HC       CH  HC       C(CH3)  HC       C  (OH) 

\/  \/  \/ 

c  c  c 

H  H  H 

Benzol  Metacresol  Pyrogallic  acid 

CeHe  C6H4  (CHa)  (OH)  CeHs  (0H)3 

^  Eliilicli :  "Die  Wertbemessuiig-  des  Diphtlierielieilserums  unci  deren.  ih^o- 
retische  Grundlagen,"  Kliu.  Jahrb.,  Jena,  VI    (2),   1897,  pp.  299-320. 


410 


IMMUNJTY 


By  r(q)laciiii(  one  ol'  tlio  il  atoms  in  the  benzol  rin^r  vvilli  iiie  methyl 
radical  (('11;.,)  we  have  toluol;  by  feplacing  one  of  IIh;  il  atoms  with 
the  hydi'oxyl  ^roup  (Oil)  wc  have  pheuol ;  by  substituting  tvvf)  hydroxyl 
groups  we  ])ave  resoreiri ;  three,  pyrogallic  acid,  etc.;  by  substituting 
one  hydrogen  atom  of  the  ring  with  the  hydroxyl  radical  and  another 
one  M'ith  the  methyl  radical  we  have  the  cresols. 
These  simple  ilhistrations  from  well-known  or- 
ganic compounds  illustrate  the  central  molecular 
jnass  with  its  side  chains  and  combining  allinities, 
to  which  the  molecule  of  protoplasm  is  likened. 

In  applying  this  analogy  to  the  molecule  of  pro- 
toplasm the  name  "receptor"  is  given  these  side 
chains,  or  secondary  atomic  complexes  of  the  molec- 
ular group.  Contrary  to  the  simple  analogies  above 
given,  each  molecule  of  protoplasm  has  many  differ- 
ent kinds  of  receptors,  as  shown  by  the  schematic 
diagram  in  Fig.  50.  These  receptors  have  a  specific 
affinity  for  the  molecules  of  food,  and  also  combine 
with  the  toxic  molecules. 

The  toxin  molecule,  according  to  Ehrlich,  con- 
sists of  two  important  parts.     One  is  known  as  the 
toxophore  group,  the  other  as  the  haptophore  group. 

The  toxopliore  group  of  the  toxin  is  that  portion  of  the  molecule 
which  exerts  a  poisonous  effect  upon  the  protoplasm  of  the  cell.  This 
group  is  less  stable  than  the  haptophore  group. 

The  licvptopliore  group  is  the  seizing  or  combining  portion  of  the  toxin 
molecule  (axretv,  to  seize  or  attack). 
The  haptophore  group  of  the  toxins  have 
specific  combining  affinities  for  the  re- 
ceptors of  certain  cells,  which  in  part  ex- 
plains the  selective  action  of  these  poi- 
sons. 


Fig.  50.— The  Cell 
WITH  Its  Various 
Combining  Groups 
OR  Side  Chains, 
Known  as  Recep- 
tors. Various  tox- 
ins are  shown  hav- 
ing specific  affinity 
for  the  proper  shaped 
receptors. 


Haptbpliof^ 


Toicophore 
(yroMp 


Fig.  51. — The  Toxin  Molecule; 
Showing  the  Haptophore 
(Combining)  Group,  and  the 
Toxophore    (Poison)    Group. 


Toxines  such  as  diphtheria  toxine 
gradually  diminish  in  toxicity,  but  retain 
the  same  power  of  chemical  combination 
with  the  antitoxin.  This  phenomenon 
explains  the  formation  of  toxoids. 

Ehrlich  inferred  the  presence  of  the 
toxoid  from  the  following  simple  experiment:  He  had  a  toxine  which 
required  0.003  c.  c.  to  kill  a  guinea-pig.  After  nine  months  this  poison 
weakened,  so  that  it  required  three  times  as  much,  that  is,  0.009  c.  c,  to 
kill  a  guinea-pig.  Nevertheless,  the  combining  power  of  the  toxine  for 
antitoxin  remained  the  same. 

Toxoids  are  altered  toxins.     They  consist  of  the  toxic  molecule  in 


IMMUNITY 


411 


Fig.  52.— The  First 
Stage  of  Anti- 
toxin Formation: 
A  Toxin  Molecule 
Anchored  to  a  Re- 
ceptor. 


which  the  toxophore  group  has  been  destroyed,  leaving  only  the  hapto- 
phore  or  combining  group,  which,  while  able  to  satisfy  the  combining 
affinities  of  the  antitoxin,  is  no  longer  able  to  poison 
the  protoplasm  of  the  cell. 

The  diphtheria  bacillus,  during  the  process  of 
its  growth  and  multiplication  in  the  body  or  in  an 
artificial  culture  inedium,  j)roduces  several  poisons, 
one  of  which  is  known  as  diphtheria  toxin.  As 
above  stated,  the  diphtheria  toxin  consists  of  a  toxo- 
phore and  haptophore  group.  In  the  body  the  lat- 
ter unites  chemically  with  the  receptors  of  the  cells. 
When  this  takes  place  one  of  two  consequences  may 
result:  either  (1)  the  cell  is  so  severely  poisoned 
that  it  dies,  or  (3)  the  living  molecule  of  proto- 
plasm is  stimulated  so  as  to  excite  a  defensive  ac- 
tion by  the  reproduction  of  its  receptors.  Con- 
tinued stimulation  produced  by  the  periodical  in- 
jection of  toxine  results  in  an  overproduction  of 
receptors,  which  finally  loosen  and  float  free  in 
the  blood  serum  and  body  juices.  Receptors 
fixed  upon  the  cells  are  called  sessile,  and  those 
that  leave  the  cell  are  spoken  of  as  free  receptors. 
Antitoxin  consists  of  these  free  receptors 
floating  in  the  blood  serum.  If  we  now  intro- 
duce toxin  into  the  blood,  it  is  immediately  neu- 
tralized by  combining  with  the  free  receptors 
through  its  haptophore  group.  All  the  combin- 
ing affinities  of  the  toxin  are  thus  satisfied  or 
saturated,  so  that  the  foxin  is  no  longer  able  to 
unite  with  the  receptors  still  attached  to  the  cell, 
and  the  poison  is  thus  rendered  harmless. 

It  is  by  no  means  a  necessary  corollary  of  the 
side-chain  theory,  as  is  often  supposed,  that  the 
receptors  are  found  only  in  those  organs  upon 
which  the  poisonous  effects  of  a  toxin  are  par- 
ticularly manifested.  On  the  contrary,  Ehrlieh 
and  Morgenroth  ^  believe  that  receptors  capable 
of  combining  with  the  toxin  are  produced  in 
many  different  parts  of  the  body,  especially  in 
tissues  and  organs  having  the  power  of  anchor- 
ing the  toxin  without  causing  serious  poisonous  effects. 

^Ehrlieh,  P.,  &  Morgenroth,  J.:  Wirkung  und  Entstehimg  der  aktiven  Stoffe 
im  Serum  nacli  der  Seitenkettentheorie.  Handbucli  der  pathogeiien  Mikroorgaii- 
ismen,  W.  Kolle,  and  A.  Wassermann,  Jena,  1904. 


Fig.  53. — The  Second 
Stage:  Continued 
Stimulation  Causes 
A  Reproduction  op 
Receptors. 


Fig.  54. — Third  Stage. 
THE  Receptors  Begin- 
ning TO  Leave  the 
Cell. 


413 


IMMUNITY 


Fig.  55. — Fotjbth  Stage: 

THE    ReCEPTOKS    HaVE 

Left  the  Cell  and 
Float  Free  in  the 
Blood — Antitoxin. 


The  connective  tissue  is  believed  to  be  specially  rich  in  receptors, 
evidenced  by  the  local  reaction  caused  by  the  subcutaneous  inoculation  of 
diphtheria  toxine,  ricin,  abrin,  and  similar  poisons.  In  fact,  one  would 
not  be  far  wrong  in  assigning  a  particular  significance,  in  the  production 
of  receptors,  to  just  those  organs  which  show  unimportant  vital  response, 
because  in  such  tissues  the  injurious  effects  of  the 
toxophore  group  are  absent  or  of  such  diminished 
importance  that  the  regenerative  powers  of  such 
tissues  are  not  retarded. 

The  presence  or  absence  of  receptors  capable 
of  binding  the  toxine,  as  well  as  their  number  and 
distribution,  are  factors  which  determine  the  sus- 
ceptibility of  different  species  of  animals  to  the 
various  toxines.  These  factors  also  determine  the 
individual  variations  in  the  susceptibility  to  poi- 
sons and  further  explain  some  instances  of  nat- 
ural immunity  to  toxins. 
An  example  is  given  by  Sachs,^  who  studied  the  reaction  of  guinea- 
pig  blood  against  arachnolysin,  a  toxin  found  in  spiders.  In  this  case 
the  complete  immunity  of  the  red  blood  cells  of  the  guinea-pig  against 
arachnolysin  is  accounted  for  by  the  entire  absence  of  the  proper  recep- 
tors, while  the  susceptibility  of  the  red  blood  cells  of  the  rabbit  to  very 
small  quantities  of  this  poison  is  accounted  for  by  the  strong  combining 
affinity  Avhich  exists  between  these  cells  of  the 
rabbit  and  the  arachnolysin. 

In  some  cases  the  production  of  receptors  may 
apparently  be  traced  in  the  development  of  cer- 
tain species.  Camus  and  Gley  ^  have  followed 
the  development  (?)  of  the  receptors  in  the  red 
blood  cell  of  the  rabbit  toward  the  hemolysin 
found  in  eel  serum.  Young  rabbits  are  much  less 
susceptible  to  this  poison  than  adult  rabbits, 
which  is  accounted  for  by  Ehrlich  as  being  due 
to  a  gradual  development  of  the  receptors  having 
proper  combining  affinities  for  the  hemolysin 
found  in  the  eel  serum. 

The  union  between  the  receptor  of  the  cell 
and  its  poison   is  not  always  a  direct  one,  as 

described  above,  but  sometimes  takes  place  through  the  intervention  of 
a  second  body,  known  variously  as  the  amboceptor,  zwisclienkurper,  im- 
mune body,  sensitizer,  fixative,  preparative,  desmon,  etc. 

This  second  order  of  immunity  is  particularly  evident  in  the  poisons 

*  Sachs,  Hans:     "Hofmeister's  Beitr.,"  Bd.  2,  H.  1-3. 

*  Quoted  by  Ehrlich,  loc.  cit. 


Fig.  56. — The  Neutral- 
ization OF  a  Toxin  by 
Antitoxin;  the  Free 
Receptors  in  the 
Blood  Have  United 
WITH  THE  Toxin  =  An- 
titoxic Immunity. 


IMMUN-ITY 


413 


Ubi^ini^Pi^'i 


Fig.  57.— The 
Second  Or- 
der OF  Im- 

M  U  NIT Y  , 

Showing 

C  OMPLE- 

ment  and 
Immune 
Body. 


that  have  a  lytic  or  dissolving  action  upon  bacteria  or  the  cells  of  the 
body,  such  as  the  bacteriolysins,  hemolysins,  and  other  cytolysins.  The 
poisonous  bodies  in  this  order  of  immunity  are  usually  spoken  of  as  "com- 
plement/^ but  also  as  the  "alexin"  (Buchner)  or  "cytase"  (Metchnikoff). 

One  of  the  remarkable  facts  connected  with  the  phe- 
nomena of  the  lytic  poisons  is  that  the  poison  itself  (the 
complement)  is  normally  present  in  the  blood.  Comple- 
ment is  thermolabile,  that  is,  it  has  less  resistance  to  heat 
than  the  intermediary  body,  which  is  thermostabile. 
According  to  Ehrlich's  theory,  immunity  can  only  be 
obtained  against  the  intermediary  body,  which  is  believed 
to  be  specific. 

Ehrlich  compares  the  intermediary  body  with  diazo- 
benzaldehyd,  which  by  means  of  its  diazo  group  is  ca- 
pable of  combining  with  a  series  of  bodies,  such  as  aromatic 
amins,  phenols,  ketomethyl  bodies,  etc.,  while  by  means 
of  its  aldehyd  group  it  may  combine  with  a  different 
series,  such  as  the  hydrazins,  ammonia  radicals,  and 
hydrocyanic  acid.  Phenol  and  hydrocyanic  acid  will  not 
directly  combine,  but,  with  diazobenzaldehyd  acting  as  an  intermediary 
body,  these  .two  substances  can  be  brought  into  combination.  Pushing 
this  comparison  further,  we  may  say  that  the  aromatic  body,  or  the 
phenol,  represents  a  constituent  of  the  blood  corpuscle.  The  diazo- 
benzaldehyd is  the  intermediary  body,  while  the  poisonous  hydrocyanic 
acid  constitutes  the  complement.^ 

Welch  ^  very  ingeniously  extended  Ehrlich's 
conception  of  immunity  to  the  bacterial  cell. 
According  to  Welch's  views,  the  bacterial  cell  has 
the  same  power  of  defensive  action  against  the 
poisons  produced  by  the  cells  of  higher  animals 
that  they  have  against  the  toxic  products  of  the 
bacteria. 

In  other  words,  there  is  a  chemical  battle. 
Both  the  bacterial  cell  and  the  body  cell  excrete 
poisonous  substances  against  each  other,  and  both 
in  turn  are  building  up  a  chemical  defense  against 
the  action  of  these  respective  poisons. 

Antitoxic  Immunity. — In  order  to  understand 
immunity  it  is  necessary  to  consider  the  nature 
and  action  of  toxins,  the  formation  and  production  of  antitoxins,  and  the 
reaction  between  toxins  and  antitoxins. 

'Vaughan  and  Novy:     "Cellular  Toxins,"  1902,  p.  131. 

^  Welch,  William  H. :  "Huxley  lecture  on  recent  studies  of  immunity  with 
special  reference  for  their  bearing  on  pathology."  Bull.  Johns  Hopkins  Hosp., 
Balto.,  XIII    (141)    Dec,  1902,  pp.  285-299. 


Fig.  58.— The  Third 
Order  of  Immu- 
nity, Showing  an 
Immune  Body 
Having  Two  Af- 
finities. 


414  IMMUNITY 


TOXINS 


Bacteria  produce  many  differej)t  kinds  of  poisouous  substances,  but 
not  all  of  these  are  toxins  in  the  specific  sense  in  which  that  term  is 
now  used.  A  toxin  may  be  defined  as  a  specific  poison  elaborated  by 
bacterial  metabolism;  it  is  soluble  in  water;  poisonous  in  minute 
amounts;  reproduces  the  essential  symptoms  and  lesions  of  the  disease; 
acts  only  after  a  period  of  incubation;  and  produces  antibodies,  namely, 
antitoxin.  The  toxins  are  thermolabile,  unstable,  and  have  a  complex 
chemical  structure. 

Toxins  are  known  only  by  their  effects  upon  animals;  they  cannot 
be  recognized  in  any  other  way.  Presumably  they  belong  to  the  higher 
proteins,  but  nothing  definite  can  be  stated  concerning  their  chemical 
structure.  They  have  never  been  isolated  in  pure  form;  they  are  not 
toxalbumins,  as  was  once  believed,  and  they  only  have  a  remote  analogy 
to  the  enzymes.  Toxins  may  be  globulins,  at  least  they  come  down 
in  the  globulin  fraction.  They  may  readily  be  precipitated  with  am- 
monium sulphate,  for  example,  but  whether  they  are  mechanically  car- 
ried down  in  the  precipitate  is  not  known.  The  toxin  molecule  is  at 
least  small  enough  to  readily  pass  through  the  pores  of  the  finest  porce- 
lain filter,  and  large  enough  not  to  dialyze  through  a  membrane. 

There  are  three  well-known  toxins:  diphtheria,  tetanus,  and  botu- 
lismus.  A  number  of  bacteria,  such  as  cholera,  dysentery,  pyocyaneus, 
and  others,  produce  a  certain  amount  of  toxic  substances  soluble  in 
water,  but  it  is  very  doubtful  whether  they  are  true  toxins  in  accord- 
ance with  the  above  definition.  Bacteria  produce  many  poisonous  sub- 
stances other  than  the  true  toxins,  such  as  acids,  alkalis,  nitrites,  fer- 
ments, ptomains,  alcohol,  hydrogen  sulphid,  etc.  Some  of  these  sub- 
stances may  play  a  part  in  the  pathogenesis  of  disease. 

Toxins  are  sometimes  divided  into  exotoxins  and  endotoxins.  The 
former  are  the  true  or  soluble  toxins;  the  latter  are  insoluble  under 
ordinary  circumstances,  and  differ  markedly  from  the  true  exotoxins. 
The  endotoxins  will  be  considered  separately. 

The  tubercle  bacillus,  the  bacillus  of  glanders,  and  other  micro- 
organisms produce  soluble  toxic  substances  specific  in  nature  but  quite 
different  from  the  true  toxins,  in  that  they  are  harmless  to  a  normal 
animal,  but  poisonous  to  one  suffering  with  the  specific  disease.  Tuber- 
culin, mallein,  and  similar  "toxins"  are  very  stable,  resist  heat  and 
other  influences,  do  not  produce  the  specific  lesions  and  symptoms  of 
the  disease,  do  not  stimulate  antitoxin  formation,  and  in  other  ways 
differ  from  the  genuine  toxins.    ' 

A  toxin  is  produced  as  a  result  of  bacterial  metabolism,  but  whether 
it  is  a  secretion,  an  excretion,  or  a  product  of  the  action  of  the  bacteria 


TOXINS  415 

upon  the  medium  (as  alcohol  and  carbon  dioxid  are  produced  by 
yeasts)  is  not  known.  It  is  known,  however,  that  toxins  do  not  result 
simply  from  the  breaking  down  of  the  dead  bacterial  cells,  as  was 
once  stated. 

It  is  now  evident  that  different  groups  of  bacteria  produce  poisons 
that  differ  essentially  in  chemical  structure  as  well  as  in  physiological 
action,  just  as  different  species  of  higher  plants  produce  various  poisons 
that  differ  markedly  in  composition  and  physiologic  action. 

Very  few  of  the  bacterial  poisons  are  injurious  when  taken  by  the 
mouth.  Diphtheria  and  tetanus  toxins  are  practically  inert,  being  de- 
stroyed largely  by  the  digestive  juices  and  not  being  absorbed  in  any 
harmful  amount.  Enormous  doses  of  these  toxins  may  be  administered 
by  the  mouth  to  susceptible  animals  without  appreciable  harm.  There 
is  one  notable  exception  in  the  case  of  the  toxin  of  the  Bacillus  botulis- 
mus,  for  this  poison  is  absorbed  by  the  intestinal  mucosa,  and  it  is  in  this 
way  that  it  produces  its  harmful  effects  in  man. 

There  are  several  poisons  produced  by  higher  plants  that  resemble 
the  true  bacterial  toxins  in  all  important  respects.  Among  them  are: 
ricin  from  the  castor  bean,  and  ahrin  from  the  jequirity  bean.  These 
toxins  of  vegetable  origin  are  known  as  phytotoxins.  They  are  soluble, 
act  only  after  a  period  of  incubation,  are  exceedingly  poisonous  in  small 
amounts,  are  destroyed  by  heating,  and  produce  specific  antibodies.  They 
are  probably  of  protein  nature,  according  to  Osborne,  Mendel,  and  Harris, 
who  obtained  ricin  in  very  pure  form.  These  poisonous  substances  of 
vegetable  origin  have  more  than  theoretical  interest,  for  it  was  through  a 
study  of  their  action  that  Ehrlich  first  obtained  a  deeper  insight  into  the 
nature  of  toxins  and  antitoxic  immunity. 

There  are  poisons  in  the  animal  kingdom  which  closely  resemble  the 
toxins,  such  as  the  venom  of  snakes,  scorpions,  spiders,  wasps,  etc. 

True  toxins  are  unstable  and  are  readily  affected  by  heat,  sunlight, 
acids,  and  various  chemicals.  They  are  much  more  unstable  in  solution 
than  in  dry  powdered  form.  Tetanus  toxin  is  more  labile  than  diph- 
theria toxin,  but  when  precipitated  with  ammonium  sulphate  and  pre- 
served as  a  dry  powder  in  a  vacuum  tube,  and  in  a  .cool,  dark  place  it 
may  be  kept  without  deterioration  for  several  years.  Diphtheria  toxin, 
in  solution,  weakens  rapidly  at  first,  and  then  comes. to  a  stage  of  equi- 
librium which  it  maintains  indefinitely  if  preserved  in  a  cold,  dark  place 
and  protected  from  the  oxygen  of  the  air. 

The  poisonous  properties  of  toxins  of  diphtheria,  tetanus,  and  botu- 
lismus  are  destroyed  at  once  by  boiling,  and  at  65°  C.  in  a  short  time. 
At  60°  C.  for  one  hour  they  lose  most  or  all  toxic  power. 

It  has  been  stated  that  one  of  the  characteristics  of  the  toxins  is 
that  they  are  poisonous  in  exceedingly  small  amounts.  Thus,  ,000,000,05 
of  a  gram  of  a  partially  purified  tetanus  toxin  will  kill  a  mouse.     Diph- 


416  IMMUNITY 

theria  toxins  have  been  obtained  so  tliat  .()()()8  c.  c.  of  the  unconcen- 
trated  fluid  (crude  filtrate)  will  kill  a  guinea-pig. 

A  true  toxin  reproduces  the  true  symptoms  and  essential  lesions 
of  the  disease.  In  this  sense  they  have  a  specific  action.  The  symptoms 
produced  in  a  susceptible  animal  by  the  inoculation  of  tetanus  toxin 
cannot  be  distinguished  from  the  disease  naturally  contracted.  The 
symptoms  produced  by  the  injection  of  diphtheria  toxin  closely  resemble 
diphtheria,  including  coagulation  necrosis  at  the  site  of  the  injection, 
fever,  depression,  postdiphtheritic  paralysis,  etc.  The  symptoms  follow- 
ing the  ingestion  of  the  toxin  of  the  Bacillus  hotulismus  are  an  exact 
counterpart  of  the  disease  produced  by  eating  food  containing  the  poison 
of  this  microorganism.  This  specific  action  is  very  important,  and,  if 
it  were  more  generally  known,  would  save  many  mistakes  in  experimental 
biology  and  its  application  to  serum  therapy.  It  is  comparatively  easy 
to  obtain  useful  antitoxins  from  true  toxins.  On  the  other  hand,  it 
seems  to  be  impossible  to  obtain  antitoxins  of  any  therapeutic  potency 
from  other  bacterial  poisons.  Thus,  tuberculin  and  mallein  and  other 
"toxins"  do  not  stimulate  antitoxic  production  and  the  so-called  antitoxic 
sera  thus  produced  have  no  protective  or  curative  value.  It  must  not  be 
forgotten  that  only  a  comparatively  few  infections  depend  upon  toxins 
and  may  be  prevented  or  cured  by  corresponding  antitoxins. 

One  of  the  characteristics  of  the  trvie  toxins  is  that  they  act  only 
after  a  period  of  incubation.  In  this  respect  they  resemble  the  natural 
disease.  Simple  chemical  poisons  may  act  at  once,  but  the  toxins  produce 
no  apparent  effect  until  a  definite  time  elapses  after  they  have  been  intro- 
duced into  the  system — even  when  overpowering  doses  are  administered. 
Thus,  the  ordinary  period  of  incubation  when  tetanus  or  diphtheria  toxin 
is  injected  into  a  susceptible  animal  is  several  days.  When  enormous 
amounts  are  injected  this  may  be  reduced  to  about  8  or  13  hours,  but 
never  less.  The  period  of  incubation  is  inversely  proportional  to  the 
amount  of  poison  injected.  The  longer  the  period  of  incubation  the 
milder  the  symptoms;  when  the  period  of  incubation  is  short  the  result 
is  almost  invariably  fatal.  The  cause  of  the  period  of  incubation  is  not 
well  understood.  A  certain  length  of  time  is  required  for  the  toxin  to 
reach  the  susceptible  cells.  This  varies  especially  in  the  case  of  tetanus, 
which  travels  up  the  nerves.  After  the  poison  reaches  the  cells  further 
time  is  required  to  combine  chemically,  and  then  more  time  to  produce 
the  injury.  On  account  of  the  period  of  incubation  large  amounts  of 
toxin  may  be  present  in  the  circulating  blood  before  the  appearance  of  the 
symptoms.  Thus,  in  horses  enough  tetanus  toxin  has  been  found  in  the 
blood  two  days  before  the  onset  of  symptoms  to  kill  a  guinea-pig,  when 
only  0.1  c.  c.  of  the  blood  serum  of  the  horse  was  injected  into  the 
guinea-pig. 

The  distribution  of  the  toxins  in  the  body  is  unequal.     Most  of  the 


TOXINS  .417 

poison  unites  with  the  cells;  some  is  destroyed  and  some  neutralized  if 
antitoxin  is  present.  Most  of  it  probably  unites  with  the  cells,  as  it  soon 
disappears  from  the  blood.  Tetanus  toxin  may  remain  a  long  time  in 
the  blood  of  an  insusceptible  animal.  Thus,  Metchnikoff  could  demon- 
strate the  presence  of  tetanus  toxin  in  the  tortoise  four  months  after 
the  injection.  After  tetanus  toxin  is  injected  it  soon  disappears  from 
the  blood,  but  if  the  tissues  are  injected  into  a  susceptible  animal  tetanus 
is  produced,  for  it  is  now  known  that  this  poison  has  a  specific  affinity 
for  the  motor  nerve  endings.  In  the  case  of  fowls  it  seems  that  this  power 
of  combining  with  the  tetanus  toxin  is  most  marked  in  the  leukocytes. 
Toxins  will  not  combine  with  all  cells  indifferently.  They  have  a  specific 
combining  affinity  for  certain  cells.  Tetanus  toxin  has  a  special  affinity 
for  the  cells  of  the  central  nervous  system.  Diphtheria  toxin  also  acts 
specifically  upon  nervous  structures;  it  is  also  a  general  protoplasmic 
poison.  These  facts  are  of  immense  importance  in  the  prevention  and 
cure  of  certain  infections,  for  a  correct  understanding  of  the  chemical 
relation  between  the  poison  and  the  particular  cell  is  of  the  greatest  fun- 
damental and  practical  value.  A  realization  of  this  fact  has  stimulated 
studies  which  are  now  in  progress  upon  the  relation  between  the  chemi- 
cal constitution  and  the  physiological  action  of  various  substances — 
studies  which  have  already  borne  fruitful  and  useful  results. 

Tetanus  toxin  may  combine  with  certain  cells  without  apparently 
injuring  them.  Diphtheria  toxin  also  combines  with  indifferent  struc- 
tures, such  as  the  connective  tissue.  There  is  evidently  a  wide  difference 
between  the  power  to  combine  and  the  power  to  injure.  The  power  to 
injure,  however,  is  not  always  evident,  as  it  depends  upon  the  importance 
and  extent  of  the  cells  affected.  Thus,  tetanus  toxin  may  combine  with 
the  leukocytes  in  such  a  way  as  to  prevent  phagocytosis.  This  may  be 
demonstrated  by  injecting  tetanus  spores  washed  free  of  toxin,  in  which 
case  the  spores  are  taken  up  by  the  leukocytes  and  their  development  is 
prevented.  If,  however,  a  slight  amount  of  toxin  is  injected  with  the 
spores,  the  poison  inhibits  phagocytosis  and  permits  the  growth  and 
multiplication  of  the  tetanus  microorganisms  and  the  further  production 
of  toxin. 

From  our  standpoint  the  most  important  property  of  a  true  toxin 
is  its  power  to  produce  specific  antitoxins.  This  will  be  giA^en  separate 
consideration. 

Ehrlieh  conceives  the  toxin  to  be  a  complex  molecule  containing 
both  a  haptophore  and  a  toxophore  group.  The  haptophore  or  seizing 
group  is  that  part  of  the  molecular  structure  which  combines  in  a 
chemical  sense  with  the  antitoxin  or  with  the  receptors  of  the  cell. 
The  toxophore  group  is  the  poisonous  part  of  the  toxin  molecule.  This 
is  usually  represented  diagrammatically.     (See  Fig.  51,  p.  410.) 

It  may  readily  be   demonstrated  by  simple  experiments  that  the 
15 


418  IMMUNITY 

toxophore  group  is  much  more  uiiHtalile  than  the  haptophore  group. 
The  toxin  may  degenerate  so  that  it  has  little  or  no  poisonous  prop- 
erties left;  however,  its  combining  properties  remain  unaltered.  Such 
a  degenerated  toxin  is  known  as  a  toxoid.  A  toxoid,  then,  is  an  altered 
toxin  which  possesses  the  combining  property  of  the  original  toxin,  but 
has  lost  its  poisonous  power.  Some  years  ago  I  proposed  to  draw  a 
distinction  between  the  terms  "toxine"  and  "toxin/'  The  toxine  is  the 
crude  filtered  culture  and  contains  several  poisonous  substances  as  well 
as  other  bodies.  The  toxin  is  the  specific  poison  in  the  toxine.  Thus, 
a  filtered  broth  culture  of  diphtheria  is  known  as  diphtheria  toxine. 
This  filtrate  contains  at  least  two  primary  metabolic  poisons:  toxin  and 
toxone.  The  toxin  produces  the  acute  symptoms  and  death;  the  toxone 
produces  the  late  paralysis.  A  filtered  broth  culture  of  tetanus  is  called 
the  tetanus  toxine.  The  filtrate  contains  at  least  two  primary  metabolic 
poisons :  tetanoplasmin  and  tetanolysin.  For  a  further  discussion  of  the 
diphtheria  and  tetanus  poisons  see  pages  414  and  436. 


ANTITOXINS 

An  antitoxin  is  an  antibody  formed  in  an  animal  through  the  stimu- 
lation of  a  specific  toxin.  The  usual  method  of  producing  an  antitoxin 
is  by  the  repeated  injections  of  increasing  amounts  of  toxine  into  a  sus- 
ceptible animal.  The  strongest  antitoxins  are  obtained  from  animals 
that  are  very  susceptible  to  the  toxine.  but  all  susceptible  animals  by 
no  means  produce  antitoxins,  although  repeatedly  injected  with  the 
appropriate  poison.  Thus,  a  guinea-pig  which  is  very  susceptible  to 
diphtheria  will  not  form  diphtheria  antitoxin,  even  after  the  repeated 
administration  of  diphtheria  toxine.  Guinea-pigs  are  also  exceedingly 
susceptible  to  tetanus  and  react  characteristically  and  violently  to  tet- 
anus toxine,  but  the  repeated  injections  of  subminimal  lethal  doses  of 
tetanus  toxine  into  a  guinea-pig  do  not  immunize  that  animal,  nor  do 
they  induce  the  formation  of  antitoxin.  In  fact,  Knorr  and  also  Behring 
and  Kitashima  have  shown  that  guinea-pigs  develop  an  increasing  sensi- 
tiveness to  repeated  injections  of  tetanus  toxin  instead  of  an  increasing 
resistance.  In  other  words,  the  guinea-pig,  a  susceptible  animal,  lacks 
the  mechanism  of  antitoxin  formation  which  is  possessed  in  such  a  high 
degree  by  horses  and  other  animals.  Antitoxin  produced  by  the  horse 
or  other  animal  when  injected  into  the  guinea-pig  will  protect  it. 

On  the  other  hand,  insusceptible  animals,  as  a  rule,  do  not  produce 
antitoxin,  but  there  are  notable  exceptions  to  this  rule.  Metchnikoff 
has  shown  that  the  cayman,  an  animal  insusceptible  to  tetanus,  will, 
however,  produce  tetanus  antitoxin  if  the  animal  is  kept  at  an  elevated 
temperature    (32°  to  37°   C),  but  not  if  kept  cold    (20°  C).     The 


ANTITOXINS  419 

mechanism  of  antitoxin  formation  is  not  understood,  and  the  only 
way  of  determining  whether  a  certain  species  of  animal  is  suitable  or 
not  is  by  experimental  trial.  There  is  a  very  great  difference  in  the 
ability  to  produce  antitoxin  even  among  different"  individuals  of  a  suit- 
able species.  Thus,  some  horses  have  this  power  developed  to  such  an 
exquisite  degree  that  they  produce  a  high  grade  of  antitoxin  for  pro- 
longed periods — years.  Other  horses  cannot  be  stimulated  to  antitoxin 
production.  This  difference  among  horses  is  well  known  to  manufac- 
turers, who  have  no  means  of  knowing  beforehand  which  horses  will  be 
profitable.  The  only  practical  method  at  present  known  is  to  discard 
those  animals  which  refuse  to  respond  to  the  stimulation  of  the  toxine 
injections. 

There  are  several  reasons  for  selecting  the  horse  for  the  production 
of  immune  sera  for  human  use.  On  account  of  its  size  it  furnishes 
large  quantities  of  blood;  the  serum  of  the  horse  is  the  blandest  blood 
serum  of  any  known  species ;  finally,  the  horse  furnishes  antitoxin  in 
higher  potency  than  any  other  known  animal. 

Just  how  and  by  what  cells  antitoxins  are  formed  in  the  body  is 
not  known.  They  are  not  formed  directly  from  the  toxines.  In  some 
way  the  toxine  excites  the  cell  to  the  formation  of  the  antibody.  The 
antibody  leaves  the  cell  and  becomes  "dissolved"  in  the  blood  and  tissue 
juices.  Perhaps  the  white  blood  cells  (Metchnikoff),  perhaps  the  con- 
nective tissue  cells  (Ehrlich),  are  chiefly  concerned.  Within  the  body 
most  of  the  antitoxin  is  found  in  the  blood,  but  it  also  exists  in  greater 
or  less  concentration  in  practically  all  the  fluids  of  the  body  and  may 
also  appear  in  the  excretions,  as  the  urine,  saliva,  milk,  and  bile. 

Nothing  definite  can  be  stated  concerning  the  chemical  nature  of 
antitoxins.  Evidence  strongly  points  to  the  fact  that  they  belong  to 
the  higher  proteins.  In  all  probability  antitoxins  are  globulins,  at  least 
they  come  down  with  the  pseudo-globulin  fraction  from  which  they  have 
not  been  separated. 

Antitoxins  are  somewhat  more  stable  than  the  toxines;  therefore, 
the  standards  by  which  diphtheria  and  tetanus  antitoxins  are  measured 
consist  of  dried  and  precipitated  antitoxins  (and  not  toxines)  preserved 
under  special  conditions.  Further,  the  toxines  have  a  more  complex 
constitution  than  the  antitoxins.  When  the  toxines  deteriorate  they 
change  qualitatively  as  well  as  quantitatively.  The  antitoxins  have  a 
simpler  constitution  and  deteriorate  simply  by  a  loss  of  power. 

Antitoxins  are  destroyed  by  heat,  acids,  and  many  chemicals.  They 
gradually  deteriorate  spontaneously  when  in  solution.  Thus,  Anderson 
has  found  that  the  average  yearly  loss  of  the  potency  of  diphtheria  anti- 
toxin at  room  temperature  is  about  20  per  cent.;  at  15°  C.  it  loses 
about  10  per  cent.;  and  at  5°  C.  about  6  per  cent.  There  is  little  dif- 
ference between  the  keeping  qualities  of  untreated  sera  and  sera  con- 


420  IMMUNITY 

centrated  and  refined  ])y  the  Oihsoii  process.  Dried  di))litli(,'ria  antitoxin 
kept  in  the  dark  at  5°  C.  retains  its  potency  practically  iininipainHl  for 
at  least  5^  years.  Antitoxic  sera  should  always  he  kept  in  a  cool, 
dark  place.  While  antitoxin  loses  some  of  its  potency  with  time,  and 
while  recently  tested  sera  of  known  unit  value  are  always  desirahle,  there 
is  absolutely  no  reason  why  a  serum,  however  old,  should  not  he  employed 
provided  a  fresh  supply  is  not  at  hand.  It  should  be  remembered  that 
antitoxins  deteriorate  quantitatively  only,  in  other  words,  an  old  antitoxin 
is  quite  as  useful  in  proportion  to  its  unit  strength  as  a  fresh  serum; 
in  fact,  antitoxic  sera  are  frequently  two  years  old  when  placed  upon 
the  market  by  manufacturers. 

Antitoxins  are  strictly  specific;  that  is,  they  neutralize  the  corre- 
sponding toxine  and  have  no  other  apparent  action  within  the  body. 
The  occasional  ill  effects,  such  as  the  serum  sickness,  following  the  injec- 
tion of  antitoxic  sera,  are  due  to  other  substances  (the  proteins  in  the 
serum)  and  not  to  the  antitoxins  themselves. 

Antitoxins  may  be  injected  subcutaneously,  intravenously,  into  the 
subarachnoid  space,  into  a  nerve,  into  the  brain  substance,  or  into  any 
of  the  body  cavities.  Antitoxins  are  practically  useless  when  given  by 
the  mouth,  as  very  little  is  absorbed.  Antitoxins  when  injected  into 
an  organism  disappear  rather  quickly.  Some  of  the  antitoxin  is  bound 
to  the  corresponding  toxine,  if  any  is  present,  some  combines  with  the 
cells,  but  the  greater  part  is  eliminated  as  antitoxin  in  the  urine,  bile, 
saliva,  etc.  The  antitoxin  contained  within  the  organism  that  produces 
it  actively,  as  the  result  of  an  attack  of  the  disease  or  as  a  result  of 
the  injection  of  toxin,  remains  a  much  longer  time  within  the  body 
than  when  the  antitoxin  is  injected  into  the  organism,  as  in  passive 
immunity.  Passive  or  antitoxic  immunity  is,  therefore,  transient;  it 
cannot  be  depended  upon  for  more  than  ten  days  or  two  weeks. 

Some  persons  have  sufficient  antitoxin  in  their  blood  to  protect  them 
against  diphtheria.  This  has  been  demonstrated  through  the  Schick 
reaction.  (See  page  166.)  In  such  cases  the  antitoxin  is  produced  nat- 
urally for  long  periods,  often  during  the  life-time  of  the  individual. 

When  antitoxic  serum  is  injected  subcutaneously  the  antitoxin  is 
absorbed  slowly.  It  requires  about  48  hours  under  these  circumstances 
for  the  antitoxin  to  appear  in  the  blood  in  maximum  amount.  There- 
fore, when  very  prompt  action  is  desired,  the  antitoxic  serum  may  be 
introduced  directly  into  the  circulation  by  intravenous  injection. 

•There  are  a  number  of  antibodies  that  are  either  true  antitoxins 
or  closely  resemble  these  antibodies.  Some  of  these  antibodies  neutralize 
the  true  bacterial  toxines,  others  the  poisons  of  animal  origin,  others 
the  poisons  of  plant  origin,  and  others  neutralize  the  activity  of  fer- 
ments. The  principal  antitoxins,  according  to  this  classification,  are 
brought  together  as  follows: 


ANTITOXINS  421 

(1)  Bacteria  Antitoxins. — The  three  principal  and  most  potent  bac- 
terial antitoxins  are  those  of  diphtheria,  tetanus,  and  botulismns.  The 
following  are  also  considered  to  have  antitoxic  properties:  pyocyaneus. 
symptomatic  anthrax,  antilenkocidin  and  antilysin  against  bacterial 
hemolysins. 

(2)  Animal  Antitoxins. — These  antitoxins  are  produced  by  animal 
poisons  belonging  to  the  venoms.  True  antibodies  are  obtained  against 
snake  venom  and  similar  poisons  in  spiders,  eels,  wasps,  scorpions,  fish, 
salamanders,  and  toads. 

(3)  Plant  Antitoxins. — These  are  antirisin,  antiabrin,  antirobin, 
and  anticrotin. 

(4)  Ferment  Antitoxins. — Antibodies  may  be  obtained  against  fer- 
ments, such  as  pepsin,  urease,  rosinease,  steapsin,  trypsin,  fibrin  ferment, 
lactase,  cyranase;  and  antibodies  may  also  be  obtained  against  the  en- 
zymes found  in  bacterial  cultures. 

There  are  comparatively  few  antitoxic  sera  of  practical  use  in  human 
therapy,  just  as  there  are  relatively  few  true  bacterial  toxines.  The 
best  known  antitoxins  are  those  of  diphtheria,  tetanus,  and  botulismus. 
Numerous  other  antitoxic  sera  are  found  upon  the  market  or  have  been 
described,  but  they  are  of  doubtful  or  no  practical  value. 

Antitoxins  are  valuable  both  as  curative  and  immunizing  agents. 
Their  preventive  action  depends  upon  the  fact  that  they  meet  the  toxin, 
unite  with  and  neutralize  it,  thus  rendering  it  harmless.  As  already 
stated,  the  antitoxins  remain  in  the  body  a  brief  time  and  their  immuniz- 
ing power,  while  of  a  high  grade,  is  transitory.  They  disappear  in 
about  ten  days  or  two  weeks;  the  immunity  must,  therefore,  be  renewed 
in  special  cases  by  repeated  injections  of  the  antitoxin  until  the  danger 
is  passed. 

This  phase  of  the  subject  is  considered  in  more  detail  under  the  pre- 
vention of  diphtheria  and  tetanus.  The  usual  immunizing  dose  for 
diphtheria  is  1,000  units,  for  tetanus  1,500  units. 

As  a  curative  agent  antitoxin  must  be  administered  early  and  in 
sufficient  amount  to  insure  success.  It  is  most  important  to  give  the 
antitoxin  early — before  the  damage  is  done.  Too  great  emphasis  cannot 
be  laid  upon  this  point.  After  the  toxin  has  united  with  the  cells  it 
cannot  be  dislodged  by  the  antitoxin.  The  importance  of  giving  antitoxin 
early  is  well  illustrated  in  the  case  of  diphtheria.  When  moderate 
amounts  (3,000  to  10,000  units)  are  injected  on  the  first  day  of  the 
disease  the  mortality  is  practically  nil.  The  mortality  increases  with 
each  hour's  delay. 

The  importance  of  giving  this  sovereign  remedy  early  is  also  illus- 
trated in  the  experiments  of  Eosenau  and  Anderson  ^  upon  the  influ- 
ence of  antitoxin  upon  post-diphtheritic  paralysis.     It  was  found  that 

^Hyg.  Lah.  Bull,  No.  38,  1907. 


422  IMMUNITY 

OIK'  iinit  of  antitoxin,  given  not  less  than  24  hours  after  a  fatal  dose 
of  diphtheria  toxine  in  a  guinea-pig,  greatly  modified  the  post-diph- 
theritic paralysis  and  saved  the  lifq  of  the  animal,  whereas  4,000  units 
given  48  hours  after  the  infection  did  not  modify  the  paralysis  or  save 
the  life  of  the  animal.  Four  thousand  units  of  antitoxin  is  an  enor- 
mous amount  for  a  guinea-pig  weighing  ahout  one-half  a  pound.  Weight 
for  weight,  it  corresponds  to  400,000  units  for  a  50-pound  child.  The 
fact  that  one  unit  of  antitoxin  saves  life  when  administered  timely, 
whereas  enormous  doses  fail  totally  when  delayed,  should  be  sufficient 
to  place  physicians  on  their  guard;  increased  dosage  cannot  atone  for 
delay.  When  cases  are  seen  late  in  the  progress  of  the  disease  it  is 
good  practice  to  give  large  doses  of  antitoxin,  for  the  reason  that  the 
poison  is  being  elaborated  continuously  and  some  of  it  is  free  in  the 
circulating  blood.  The  antitoxin  unites  with  and  neutralizes  the  uncom- 
bined  poison  and  thus  protects  the  cells  against  further  damage.  This 
refers  to  tetanus  as  well  as  diphtheria.  Tetanus  antitoxin  is  a  very  val- 
uable immunizing  agent,  but  is  of  less  value  after  symptoms  have  ap- 
peared, for  then  most  of  the  damage  has  been  done. 

Preparation  of  Antitoxin. — The  antitoxin  used  in  human  therapy  is 
practically  always  contained  in  the  blood  serum  or  blood  plasma  of 
the  horse.  The  blood  is  drawn  from  the  jugular  vein  into  sterile  bottles. 
The  bleeding  should  never  be  done  until  a  week  or  more  has  elapsed  since 
the  last  injection  of  toxine,  so  as  to  allow  time  for  the  disappearance  of 
the  poison  from  the  circulation.  The  horses  are  given  no  food  for  about 
24  hours  preceding  the  bleeding,  so  that  the  blood  may  not  contain  the 
fresh  products  of  digestion  and  metabolism.  After  the  blood  is  drawn  it 
may  be  allowed  to  clot  spontaneously.  In  the  case  of  horse  blood  this 
takes  place  more  quickly  at  room  temperature  than  in  the  ice  chest. 
The  clot  is  allowed  to  contract  for  a  few  days  and  the  serum  containing 
the  antitoxin  is  then  drawn  off  with  a  pij^ette  or  simply  decanted.  In 
this  way  a  clear  transparent  serum  is  obtained  which,  if  protected  against 
contamination  by  the  usual  bacteriological  precautions,  is  sterile  and 
may  be  preserved  indefinitely.  It  is  almost  a  universal  practice,  however, 
to  add  a  preservative;  either  chloroform  (0.3  per  cent.),  phenol  (0.5  per 
cent.),  or  tricresol  (0.4  per  cent.).  These  preservatives  in  the  amounts 
named  are  harmless  when  injected  and  have  practically  no  effect  upon 
the  antitoxin  itself.  They  gradually  precipitate  the  albuminous  matter 
from  the  serum,  which  settles  as  a  white  amorphous  deposit  and  which 
may  be  disregarded,  as  it  is  harmless.  Chloroform  produces  a  better- 
looking  serum,  but  the  less  volatile  preservatives  are  usually  preferred 
on  account  of  their  stability  and,  hence,  greater  reliability. 

By  the  method  of  allowing  the  blood  to  coagulate,  as  above  described, 
only  about  one-third  of  its  volume  is  recovered  as  antitoxic  serum.  A 
much  greater  yield  may  be  obtained  by  citrating  the  blood :  sodium 


ANTITOXINS  423 

citrate  prevents  the  clotting  of  blood.  A  solution  of  this  salt  is  placed 
in  the  bottle  which  is  to  receive  the  blood  directly  from  the  horse,  in 
sufficient  amount  to  be  present  in  1  per  cent,  of  the  whole  blood.  The 
corpuscles  soon  settle  to  the  bottom,  leaving  the  clear  supernatant,  plasma, 
which  is  then  decanted  or  drawn  off  with  a  pipet.  In  this  way  the  yield 
of  antitoxic  fluid  is  about  90  per  cent,  of  the  volume  of  the  blood,  and  is, 
therefore,  preferred  to  the  less  economical  method  of  allowing  the  blood 
to  clot. 

The  citrated  plasma  may  further  be  "purified"  or  concentrated  by 
various  methods,  that  generally  used  being  a  modification  of  Gibson's  ^ 
method,  based  upon  the  earlier  experiments  of  Atchinson. 

Ordinary  antitoxic  serum  contains  serum  globulins  (antitoxic),  serum 
globulins  (non-antitoxic),  serum  albumins  (non-antitoxic),  serum  nu- 
cleoproteids  (non-antitoxic),  cholesterin,  lecithin,  traces  of  bile  color- 
ing matter,  traces  of  bile  salts  and  acids,  traces  of  inorganic  blood 
salts,  and  other  non-proteid  compounds.  Refined  serum  contains  serum 
globulins  (antitoxic),  traces  of  serum  globulins  (non-antitoxic)  dissolved 
in  dilute  saline  solution. 

Gibson's  Method  of  Concentrating  Diphtheria  Antitoxin. — Gibson  ^ 
prepared  a  refined  and  concentrated  diphtheria  antitoxin  by  first  pre- 
cipitating the  antitoxic  serum  with  a  half  saturation  of  ammonium  sul- 
phate. This  throws  down  the  globulins.  The  precipitate  is  collected 
and  dissolved  in  a  saturated  solution  of  sodium  chlorid.  Only  a  por- 
tion of  the  globulins,  but  all  of  the  antitoxin,  passes  into  the  solution. 
Through  the  precipitation  by  ammonium  sulphate  and  solution  in  so- 
dium chlorid  the  nucleoproteins  and  the  insoluble  globulins  are  elim- 
inated. The  soluble  globulins  with  the  antitoxin  are  now  precipitated 
by  the  addition  of  acetic  acid.  The  precipitate  is  collected  upon  a  fil- 
ter, partially  dried,  and  finally  placed  in  a  sac  of  parchment  membrane 
and  dialyzed  in  running  water.  The  resulting  fluid  is  then  an  anti- 
toxic solution  of  soluble  globulins  which  is  rendered  neutral,  and  suffi- 
cient sodium  chlorid  is  added  to  make  it  isotonic.  In  carrying  out  the 
process  there  is  a  loss  of  about  30  per  cent,  of  antitoxin  units  because 
of  retention  on  filters,  loss  in  dialysis,  etc.,  but  the  resulting  solution 
of  antitoxic  globulins  has  a  greater  concentration  than  the  original  serum 
from  which  it  was  obtained.  Thus,  a  serum  containing  only  200  units 
of  antitoxin  per  c.  c.  may,  after  concentration  with  Gibson's  method, 
contain  as  much  as  500  units  of  antitoxin  per  c.  c. ;  and  one  having  an 
original  potency  of  300  may  contain  700  units  or  more  per  c.  c.  in  the 
final  product. 

The  advantages  of  the  antitoxic  globulins  are  that  a  smaller  bulk  is 
required  to  give  a  corresponding  number  of  units  of  antitoxin.     Less 

^Jour.  of  Biolog.  Chem.,  Vol.  I,  1906. 
'Ibid.,  Vol.  I,  Nos.  2  &  3,  Jan.,  1906,  p.  161. 


424  IMMUNITY 

foreign  proteins  are  injected,  and  there  is  a  resulting  decrease  in  the 
number  and  severity  of  those  showing  the  serum  sickness.  By  the  method 
of  concentration  and  refining,  antitoxic  sera  too  weak  for  practical  pur- 
poses are  thus  saved. 

Dried  Antitoxin, — The  antitoxic  serum  or  the  antitoxic  plasma  may 
be  dried  by  any  of  the  methods  in  common  use,  care  being  taken  to 
prevent  bacterial  contamination  and  also  to  prevent  overheating.  The 
antitoxic  fluid  is  usually  dried  in  shallow  layers  on  pans  in  a  vacuum 
apparatus,  to  the  form  of  golden  yellow  amorphous  flakes.  These  are 
ground  to  a  powder.  About  100  c.  c.  of  serum  or  plasma  yields  ap- 
proximately 10  grams  of  dried  residue.  It  is,  therefore,  necessary  to 
redissolve  the  dried  antitoxin  in  at  least  10  parts  of  normal  saline  solu- 
tion. The  advantages  of  antitoxin  in  the  dried  form  are  that  when  pre- 
served in  a  cool,  dark  place  it  retains  its  potency  practically  indefinitely. 
The  only  disadvanage  is  that  it  goes  into  solution  with  some  difficulty, 
and  the  making  of  this  solution  requires  not  only  time,  but  is  rather 
inconvenient. 

Mode  of  Action. — The  mode  of  action  of  antitoxins  is  now  fairly  well 
understood.  One  thing  is  certain,  and  that  is  that  the  antitoxin  unites 
directly  with  the  toxin.  This  may  be  readily  demonstrated  by  adding  a 
little  antitoxin  to  some  toxin  in  a  test  tube  and  then  injecting  the 
mixture  into  a  susceptible  animal;  no  symptoms  result.  Diphtheria 
antitoxin  combines  with  diphtheria  toxin  more  quickly  than  tetanus  an- 
titoxin combines  with  its  poison.  Thus,  in  the  case  of  diphtheria  the 
union  between  the  poison  and  its  antibody  is  complete  in  less  than 
twenty  minutes  at  room  temperature,  while  in  the  case  of  tetanus  it 
requires  one  hour.  These  facts  are  of  practical  importance  in  the  work 
of  standardization,  in  which  case  the  toxines  and  antitoxins  are  mixed 
in  the  test  tube  and  the  combining  action  must  be  complete  before  the 
mixtures  are  injected  into  the  test  animals  in  order  to  insure  accurate 
results. 

Ehrlich  believes  and  strongly  defends  his  assumption  that  an  anti- 
toxin unites  with  a  toxin  just  as  an  acid  unites  with  an  alkali,  that  is, 
the  one  has  a  strong  chemical  affinity  for  the  other,  and  the  union  is 
simple  and  direct.  On  the  other  hand,  Arrhenius  and  Madsen  insist 
that,  instead  of  considering  the  toxine  as  a  complex  mixture  of  various 
substances,  such  as  a  toxin,  tox one,  etc.,  it  would  be  simpler  to  consider 
it  as  a  single  (at  least  homogeneous)  substance  which  has  a  very  weak 
affinity  for  the  antitoxin  and  that  in  mixtures  containing  toxin  and 
antitoxin  there  are  always  both  free  toxin  and  free  antitoxin.  Arrhenius 
draws  his  analogy  from  known  facts  in  physical  chemistry,  particularly 
from  studies  upon  the  relation  between  solutions  of  boracic  acid  and 
ammonia.  These  two  substances  have  a  comparatively  weak  affinity  for 
each  other,  and  in  mixtures  all  the  boracic  acid  does  not  combine  with  all 


ENDOTOXINS  425 

the  ammonia,  but  there  are  always  present  both  free  ammonia  and  free 
boracic  acid. 

When  ammonia  and  boracic  acid  are  brought  together  in  watery  solu- 
tion some  of  the  ammonia  at  once  unites  with  some  of  the  boracic  acid 
to  form  ammonium  borate.  This  reaction  starts  with  a  certain  velocity, 
but  as  the  mass  of  ammonium  borate  increases  the  velocity  of  the  reaction 
gradually  diminishes.  After  a  time  a  condition  is  reached  when  the 
ammonium  borate  has  a  maximum  value  and  does  not  further  increase, 
no  matter  how  long  the  reaction  is  allowed  to  proceed  under  the  given 
conditions. 

When  this  condition  of  equilibrium  is  reached  the  mass  contains  a 
certain  quantity  of  water,  ammonia,  boracic  acid,  and  ammonium  borate ; 
but  these  substances  are  not  at  rest.  The  ammonia  and  boracic  acid  will 
always  react  whefl  in  the  presence  of  each  other,  whether  or  not  am- 
monium borate  is  present.  But,  as  the  appropriate  amount  of  ammonium 
borate  remains  constant,  it  is  understood  while  this  continuous  association 
between  the  ammonia  and  the  boracic  acid  is  going  on  there  is  at  the 
same  time  a  reversible  action — that  is,  a  dissociation  of  the  ammonium 
borate  to  reform  ammonia  and  boracic  acid.  These  two  reactions  take 
place  simultaneously. 

Arrhenius  believes  that  the  diphtheria  poison  changes  slowly  accord- 
ing to  the  laws  of  monomolecular  reactions,  that  the  toxin  combines 
feebly  with  the  antitoxin,  the  equilibrium  constant  being  equal  for  both. 
The  claim,  however,  that  the  toxine  is  a  simple  substance  having  a  weak 
affinity  for  the  antitoxin  and  that  the  combination  of  toxin  and  antitoxin 
follows  the  Guldberg-Waage  law,  and  that  the  reaction  is,  therefore, 
reversible,  seems  untenable  in  the  light  of  the  evidence  brought  forward 
by  Ehrlich,  Nernst,  Michaelis,  and  others. 


ENDOTOXINS 

In  contradistinction  to  the  soluble  or  exotoxins,  there  is  a  group  of 
poisons  known  as  endotoxins.  The  existence  of  endotoxins  was  taken 
for  granted  before  they  were  actually  demonstrated.  As  soon  as  it  was 
found  that  only  some  bacteria  produce  soluble  specific  toxines  it  was 
at  once  assumed  that  the  other  bacteria  must  contain  similar  poisons, 
but  closely  bound  within  the  cell  and  insoluble  in  ordinary  culture  fluids. 
It  was  further  assumed  that  these  endotoxins  were  in  some  way  set  loose 
in  the  body  and  thereby  produced  the  lesions  and  symptoms  of  the  disease. 
The  endotoxins  are  conceived  to  be  poisons  very  closely  bound  up  with 
the  protein  contents  of  the  bacterial  cell,  and  are  liberated  in  the  body 
when  the  bacterial  cell  dies  and  disintegrates.  However,  it  by  no  means 
follows  that  these  endotoxins  are  poisons  similar  in  action  and  com- 


426  IMMUNITY 

position  to  the  soluble  true  toxins;  in  fact,  there  is  evidence  to  indicate 
the  contrary.  It  is  true  that  some  bacteria,  such  as  the  dysentery  bacillus, 
cholera  vibrio,  and  a  few  other  microorganisms  that  produce  little  or  no 
soluble  toxine,  may  be  ground  up  so  that  the  bacterial  cells  are  mechanic- 
ally ruptured,  thus  liberating  the  endotoxin.  In  some  cases  of  so-called 
endotoxic  action  the  reaction  of  anaphylaxis  appears  to  be  the  best  ex- 
planation. 

TETANUS   TOXIN 

On  account  of  its  virulence,  its  solubility,  and  the  characteristic 
contractions  which  it  induces,  the  poison  of  tetanus  has  been  a  con- 
venient and  favorite  subject  of  investigation.  It  was  the  first  of  the 
bacterial  toxines  to  give  fruitful  results  in  serum  therapy.  The  toxine 
is  readily  soluble  in  the  medium  in  which  tetanus  grows,  whether  fluid 
or  solid;  it  diffuses  throughout  gelatin  or  agar.  The  culture  filtered 
free  of  all  bacterial  cells  is  called  the  tetanus  toxine.  This  is  really 
a  complex  substance  containing  various  poisons  and  other  bodies.  Two 
of  these  poisons  in  particular  have  been  studied :  tetanospasmin  and 
tetanolysin.  It  is  the  former  which  produces  the  convulsions  character- 
istic of  the  disease  and  concerns  us  especially.  This  poison  is  a  type  of  a 
true  toxine.  It  is  exceedingly  poisonous  in  very  small  quantities ;  is 
readily  rendered  inert  by  heat  (60°  C.) ;  contains  both  a  toxophore  and 
haptophore  group;  produces  antibodies  when  introduced  into  susceptible 
animals,  and  produces  symptoms  only  after  a  definite  period  of  incuba- 
tion. In  all  these  characteristics  tetanus  toxine  resembles  diphtheria 
toxine. 

Tetanus  toxine  is  one  of  the  most  poisonous  substances  known. 
Amounts  as  small  as  .000,006  gram  of  the  standard  precipitated  toxine 
prepared  by  me  in  the  Hygienic  Laboratory  at  Washington  invariably 
kills  a  guinea-pig  weighing  350  grams  in  about  four  days.  As  this  pre- 
cipitate consists  mostly  of  albumins,  peptone,  amino  acids,  volatile  sub- 
stances, ammonium  sulphate,  and  other  salts,  it  will  be  seen  that  but  a 
small  proportion  of  the  weight  consists  of  pure  poison.  Brieger  and 
Cohn  found  that  their  strongest  tetanus  toxine  killed  mice  weighing  15 
grams  when  given  subcutaneously  in  doses  of  .000,000,05  grams,  and 
they  calculate  that  .000,23  gram  would  be  a  fatal  dose  for  a  man  weigh- 
ing 70  kilograms. 

Tetanus  toxine  is  not  equally  toxic  for  all  species  of  animals;  on 
the  other  hand,  there  is  an  extraordinary  constancy  in  its  toxicity  upon 
individuals  of  the  same  species;  that  is,  the  same  quantity  of  toxine  per 
gram  weight  of  a  particular  animal  always  produces  similar  results. 

Tetanus  toxine  is  harmless  when  given  by  the  mouth.  It  is  not  ab- 
sorbed from  the  intact  intestinal  tract,  but  is  affected  by  the  digestive 


TETANUS    TOXIN  427 

juices.  I  have  fed  guinea-pigs  Avith  as  much  as  24,000  and  mice  18,000 
times  the  minimal  lethal  dose  of  tetanus  toxine  without  producing  any 
apparent  ill  elfects. 

All  attempts  to  isolate  the  specific  toxine  as  a  definite  chemical 
compound  have  proved  unavailing.  We  are  totally  ignorant  of  its  chem- 
ical nature.  The  only  way  by  which  it  may  be  recognized  is  through  its 
effects  upon  animals.  By  this  means  we  are  enabled  to  determine  not 
only  the  presence  of  the  poison,  but  also  to  estimate  its  concentration  in 
a  solution  and  to  watch  its  deterioration. 

Brieger  in  1886  isolated  from  a  contaminated  growth  a  basic  sub- 
stance or  ptomain  which  he  called  "tetanin"  (C13H3N2O4).  Shortly 
afterward  he  obtained  another  ptomain  which  he  named  "tetanotoxin" 
(C5H11N).  These  substances  caused  muscular  contractions  when  in- 
jected into  mice,  and  Brieger  believed  them  to  be  the  true  poison  of 
tetanus.  They  are  now  only  of  historical  interest,  for  the  studies  of 
Kitasato  and  Weyl  in  1890  with  pure  cultures  of  tetanus  found  that 
Brieger's  purified  extracts  did  not  produce  the  characteristic  symptoms 
of  tetanus  in  experimental  animals. 

Brieger  and  Fraenkel  in  1890  obtained  an  alcoholic  precipitate  from 
filtered  broth  cultures  which  they  termed  "toxalbumin"  and  which  had 
undoubted  toxic  properties.  Hayahsi  concludes  from  his  work  upon  the 
subject  that  the  toxin  isolated  according  to  the  Brieger-Boers  method, 
as  well  as  by  his  own  modification,  shows  a  definite  albumin  reaction. 
However,  this  does  not  prove  that  the  toxin  itself  is  a  protein. 

The  powerful  action  of  the  tetanus  poison  in  such  minute  amounts, 
its  thermolability,  and  the  period  of  incubation  lend  countenance  to 
the  view  that  the  toxin  may  be  a  ferment.  There  is,  therefore,  nothing 
but  analogy  to  class  tetanus  toxin  with  the  ferments. 

Ehrlich,  in  a  parallel  work  to  his  researches  upon  the  constitution 
of  diphtheria  toxine,  showed  that  tetanus  toxine  contains  both  a  toxo- 
phore  and  a  haptophore  group  and  that  the  antitoxic  immunity  is  ex- 
plained by  the  presence  of  free  receptors  in  the  blood.  The  receptors 
combine  directly  in  a  chemical  sense  with  the  haptophore  group,  thus 
neutralizing  the  poison. 

Ehrlich,^  1898,  definitely  proved  that  tetanus  toxin  contains  at  least 
two  poisons:  (1)  tetanolysin  and  (2)  tetanospasmin.  He  showed  that 
these  two  poisons  do  not  always  appear  in  the  same  relative  propor- 
tion in  different  preparations.  Some  of  the  toxins  that  have  strong 
tetanic  properties  have  weak  hemolytic  action,  and  ince  versa.  The 
hemolytic  affinity  of  the  toxin  weakens  much  quicker  than  the  tetano- 
spasmin. This  occurs  spontaneously  as  well  as  when  it  is  heated  to 
50°  C.  for  20  minutes.  The  two  poisons  have  different  combining  af- 
finities.    If  tetanus  toxine  is  brought  into  contact  with  red  blood  cor- 

^  Ehrlich,  P.:     Berl.  klin.  Woch.,  1898,  No.   12. 


4,'.^  8  IMMUNITY 

puscles,  the  greatest  part  of  tlie  tetaiiolysiii  is  hound  liy  \]\v,  red  cor- 
puscles, while  the-  tetanospasmiii  remains  in  the  s(^lutioii.  I'^ach  f)n(' 
of  these  two  poisons  has  its  own  antitoxin.  If  several  different  tetanus 
sera  are  examined,  it  will  be  found  that  they  liave  no  parallel  neutraliza- 
tion for  tetanolysin  and  tetanospasmin.  In  one  particular  case  Ehrlich 
found  a  serum  that  was  strong  antispastic  and  had  practically  no  antilytic 
power. 

Bolton  and  Fisch  ^  have  shown  that  the  toxine  makes  its  appearance 
in  the  blood  of  the  horse  several  days  before  any  symptoms  of  tetanus 
are  observed,  and  that  it  gradually  increases  until  about  two  days  be- 
fore symptoms  become  noticeable,  and  then  it  suddenly  diminishes  and 
even  disappears  in  some  cases.  The  amount  of  toxine  varies  consider- 
ably in  different  horses.  In  one  instance  the  serum  of  a  horse,  about 
two  days  before  symptoms  of  tetanus  appeared,  was  sufficient  to  kill  a 
guinea-pig  in  the  dose  of  0.1  c.  c.  The  fact  that  tetanus  toxine  may 
appear  in  such  large  quantities  in  the  blood  without  symptoms  of  tetanus 
is  of  very  great  practical  importance  in  the  production  of  both  diphtheria 
and  tetanus  antitoxins  and  other  therapeutic  sera. 

Tetanus  toxine  is  readily  destroyed  by  heat,  sunlight,  acids,  and 
other  agencies.  Anderson,  1907,  found  that  when  tetanus  toxine  is 
exposed  to  5  per  cent,  formalin  for  six  hours  a  guinea-pig  is  able  to 
withstand  100  minimal  lethal  doses  of  this  formalinized  poison.  Three 
per  cent,  formalin  after  twenty-four  hours'  exposure  destroys  the  toxine ; 
it  destroys  a  part  of  the  toxine  in  one  hour,  its  action  increasing  with 
the  length  of  exposure.  This  indicates  that  formalin  should  prove  a 
useful  substance  for  local  application  to  certain  wounds. 

Tetanus  toxine  is  prepared  from  bouillon  cultures  grown  anaerobically 
at  37°  C.  for  6  to  15  days.  The  culture  fluid  is  then  filtered  through 
porcelain  or  diatomaceous  earth ;  the  germ-free  filtrate  contains  the 
poison.  This  is  used  to  inject  into  horses  for  the  purpose  of  producing 
tetanus  antitoxin.  Tetanus  toxin  in  solution  is  so  unstable  that  it  cannot 
be  depended  upon  for  the  purpose  of  accurate  tests.  From  a  practical 
standpoint  it  is  all-important  to  obtain  a  stable  poison.  Herein  lies  the 
crux  of  the  problem,  so  far  as  the  standardization  of  tetanus  toxin  is 
concerned.  If  soluble  poisons  are  used  to  measure  the  value  of  antitoxic 
serums,  as  is  the  case  with  the  German  method,  it  is  foiind  necessary 
to  redetermine  through  a  series  of  mice  the  strength  of  the  toxine  each 
time  a  serum  is  tested.  The  fact  that  tetanus  toxine  does  not  exhibit 
the  same  constancy  as  diphtheria  toxine  in  solution  has  thrown  much 
confusion  and  no  little  difficulty  into  the  work  of  standardizing  its  anti- 
toxin. 

Eosenau  and  Anderson  succeeded  in  obtaining  a  dry  poison  by  pre- 
ciiDitating  it  from  solution  with  ammonium  sulphate.     The  excess  of 

^  Trans.  Assoc,  of  Am.  Plujs.,  XVII,   1902,  pp.  462-467. 


TETANUS    TOXIN  439 

salt  is  removed  in  the  dialyzer.  The  toxine  may  be  further  purified  by 
again  bringing  it  into  solution  and  reprecipitating  it  several  times.  This, 
however,  is  not  necessary  in  ordinary  work.  The  precipitate  is  collected 
and  dried  in  a  vacuum  over  sulphuric  acid  and  preserved  in  vacuum  tubes, 
under  the  influence  of  pentaphosphoric  (P2O5)  acid  in  a  cool,  dark 
place.  Under  these  conditions  the  poison  does  not  diminish  in  toxicity 
during  a  period  of  many  years.  It  loses  its  toxicity  rather  slowly  when 
exposed  to  light,  heat,  and  other  influences.  One  of  the  sealed  tubes 
sent  from  Washington  to  Manila  arrived  there  without  appreciable  loss 
of  strength.  It  is  this  dried  poison  which  is  distributed  to  manufacturers 
and  other  laboratories  engaged  in  the  work  of  standardizing  tetanus  anti- 
toxin. 

Mode  of  Action. — It  has  been  known  for  a  very  long  time  that 
tetanus  toxin  affects  chiefly  the  central  nervous  system,  but  it  is  only 
comparatively  recently  that  it  has  been  demonstrated  experimentally  in 
what  way  the  poison  reaches  the  nerve  centers.  For  this  information 
we  are  indebted  especially  to  the  work  of  Marie  and  Morax/  1902,  and 
Meyer  and  Eansom,^  1903.  It  is  now  definitely  known  that  the  motor 
nerves  have  a  specific  affinity  for  tetanus  toxin.  When  the  toxin  is  placed 
subcutaneously  the  adjacent  motor  nerve  endings  at  once  begin  to  take 
it  up  and  it  is  then  transported  in  the  axis  cylinder  to  the  cord.  This 
action  may  be  compared  to  the  absorption  of  nourishing  liquids  by  the 
roots  of  a  plant.  The  lymphatics  also  absorb  much  of  the  toxin  and  in  a 
short  while  it  appears  in  the  blood  stream,  which  carries  it  to  all  parts 
of  the  body,  where  again  it  is  absorbed  by  the  motor  nerve  endings  wdiich 
are  bathed  in  the  toxin-laden  fluid.  The  toxin  does  not  reach  the  nerve 
cells  directly  through  the  blood,  for  even  after  introducing  the  poison  into 
the  subarachnoid  space  there  is  a  general  poisoning  and  not  a  cerebral 
tetanus. 

The  injection  of  tetanus  toxin  into  the  posterior  root  of  the  spinal 
nerves  leads  to  a  tetanus  dolorosus  which  is  characterized  by  strictly 
localized  sensitiveness  to  pain.  According  to  Meyer  and  Eansom,  the 
reason  why  the  sensory  nerves  do  not  play  any  role  in  the  conduction 
of  the  poison  lies  in  the  presence  of  the  spinal  ganglion,  which  places 
a  bar  to  the  advance  of  the  poison. 

Milchner  in  1898  showed  that  tetanus  toxin  combines  chemically 
with  the  central  nervous  system.  A  direct  combination  takes  place  when 
tetanus  toxin  and  brain  substance  are  mixed  in  the  test  tube.  This 
action  has  been  studied  by  Metchnikoff,  Wassermann,  and  Takaki,  Eoux 
and  Borrel,  Denys,  and  others.  It  seems  that  the  phenomenon  of  the 
fixation  of  the  tetanus  toxin  by  nervous  tissue,  in  spite  of  some  analogies, 

*  Marie  and  Morax:     Annates  de  Vlnstitut  Pasteiir,  XVIII,  1902,  p.  818. 
^ Meyer  and  Ransom:      Archiv  fiir  experiment elle  Pathologie  und  Pharma- 
cologie,  Vol.  49,  1903. 


430  IMMUNITY 

cannot  be  likened  to  the  action  of  antitoxin  or  toxin.  The  toxin  at  first 
fixed  by  the  nervous  substance  again  becomes  free  in  vitro  and  in  vivo. 
The  union  between  the  tetanus  toxin  and  the  nervous  tissue  appears  to  be 
a  feeble  chemical  adsorption  which  may  be  readily  dissociated  and  which 
does  little  harm  to  the  toxin.  On  the  other  hand,  the  union  between 
toxin  and  antitoxin  is  much  more  stable  and  definite. 


TETANUS    ANTITOXIN 

Tetanus  antitoxin  is  contained  in  the  blood  serum  of  horses  highly 
Immunized  by  repeated  injections  of  tetanus  toxine.  It  is  necessary  to 
begin  with  exceedingly  small  doses,  for  the  reason  that  horses  are  very 
susceptible  to  tetanus.  Time  may  be  gained  and  accidents  avoided  by 
guarding  the  first  few  injections  with  tetanus  antitoxin.  The  injections 
are  given  at  intervals  of  about  a  week  and  may  be  rapidly  increased 
so  that  in  a  few  months  a  horse  will  be  able  to  stand  several  hundred 
cubic  centimeters  of  an  exceedingly  strong  poison.  The  horse  should 
never  be  bled  for  the  purpose  of  procuring  the  antitoxic  serum  imtil  at 
least  two  weeks  have  elapsed  since  the  last  injection  of  the  toxine,  in 
order  to  be  sure  that  all  the  poison  has  disappeared  from  the  circulating 
blood. 

Tetanus  antitoxin  is  an  antibody  which  corresponds  in  all  essential 
respects  to  diphtheria  antitoxin.  It  neutralizes  the  poison  probably  by 
direct  chemical  combination  whether  in  the  body  and  in  the  test  tube. 
In  human  therapy  it  is  used  either  by  subcutaneous  or  intravenous  in- 
jection, by  injecting  it  directly  into  the  large  nerve  trunk  leading  from 
the  wound,  by  placing  it  in  the  subarachnoid  space,  or  by  injecting  it 
directly  into  the  brain  substance.  It  is  also  used  in  dried  form  as  a  dust- 
ing powder  upon  the  wound.  When  tetanus  antitoxin  is  administered 
subcutaneously  it  is  absorbed  rather  slowly.  Knorr  found  the  maximum 
quantity  in  the  blood  only  after  24-40  hours,  and  from  this  time  on  the 
amount  steadily  decreases,  so  that  by  the  sixth  day  only  one-third  of  the 
actual  quantity  is  present;  by  the  twelfth  day  only  one-fiftieth,  and  at 
the  end  of  three  weeks  no  antitoxin  whatever  could  be  demonstrated. 
Hence,  it  is  important  to  give  the  first  dose  in  a  case  of  tetanus  intra- 
venously. 

The  specific  action  of  tetanus  antitoxin  makes  it  a  valuable  prophy- 
lactic ;  it  has  less  use  as  a  curative  agent,  for  the  reason  that  after  symp- 
toms have  appeared  most  of  the  damage  to  the  nerve  cells  has  been  done. 
While  antitoxin  has  a  limited  value  as  a  remedial  measure,  it  is  by  no 
means  to  be  neglected,  for  the  reason  that  it  neutralizes  the  free  poison  in 
the  circulating  blood  and  elsewhere  in  the  body  and  thus  prevents  further 
damage  of  the  nerve  cells.    In  the  use  of  tetanus  antitoxin  as  a  preventive 


STANDAEDIZATIOJ^T    OF   ANTITOXIC    SEKA  431 

it  should  be  remembered  that  it  is  quickly  eliminated^  from  the  body,  so 
that  in  wounds  which  continue  to  suppurate  with  foul-smelling  pus,  espe- 
cially when  the  pus  contains  end-spore-bearing  rods,  and  in  all  wounds  in 
which  there  is  a  suspicion  of  special  danger  about  1,500  units  of  the 
tetanus  antitoxin  should  be  administered  at  intervals  of  about  ten  days. 
(See  also  page  81.) 


STANDARDIZATION    OF    ANTITOXIC    SERA 

The  method  of  measuring  the  strength  of  diphtheria  and  tetanus 
antitoxins  is  exceedingly  accurate  and  satisfactory.  The  tests  are  physi- 
ological, that  is,  depend  upon  animal  experimentation.  Guinea-pigs  are 
used  because  they  are  particularly  susceptible  to  both  tetanus  and  diph- 
theria toxines  and  react  to  these  poisons  so  uniformly  that  they  serve 
the  purpose  of  an  accurate  analytical  balance.  In  order  to  obtain  precise 
results  it  is  essential  that  all  the  conditions  of  the  test  be  uniform.  It  is, 
therefore,  advisable  to  follow  the  official  methods,  which  have  been  pre- 
scribed in  great  detail.  All  antitoxic  sera  upon  the  American  market 
are  standardized  in  accordance  with  the  official  unit  dispensed  by  the 
federal  government.  This  work  is  done  in  the  Hygienic  Laboratory  of 
the  Public  Health  Service. 

The  Standardization  of  Diphtheria  Antitoxin. — The  immunity  unit 
for  measuring  the  strength  of  diphtheria  antitoxin  may  be  defined  as 
the  neutralizing  power  possessed  by  an  arbitrary  quantity  of  diphtheria 
antitoxic  serum  kept  under  special  conditions  to  prevent  deterioration 
in  an  authorized  laboratory. 

From  a  theoretical  viewpoint  the  unit  may  be  defined  as  that  quan- 
tity of  diphtheria  antitoxic  serum  which  will  Just  neutralize  200  mini- 
mal lethal  doses  of  a  pure  poison.  By  a  "pure"  poison  is  understood 
one  containing  only  toxin  and  no  toxoid,  toxone,  or  other  substance 
capable  of  uniting  with  the  antibodies. 

The  first  definition  may  be  compared  to  the  platino-iridium  bars  kept 
under  special  conditions  in  Paris  or  Washington  as  the  standard  yard  or 
meter.  If  all  the  meter  bars  or  yardsticks  were  lost  it  would  be  difficult, 
if  not  impossible,  to  reproduce  others  having  the  exact  lengths  of  the 
originals.  These  standard  measures  are,  therefore,  guarded  against  de- 
terioration just  as  the  standard  antitoxic  sera  are  preserved  under  strict 
conditions  of  light,  heat,  moisture,  etc.,  in  the  Hygienic  Laboratory  of 
the  Public  Health  Service  at  Washington.  From  time  to  time  duplicates 
of  this  serum  are  made  to  guard  against  deterioration  or  accident  to  the 
original. 

The  second  definition  may  be  compared  to  the  original  conception 
of  the  meter,  which  was  intended  to  be  one  ten-millionth  of  the  quad- 


433  IMMUNITY 

rant  of  a  great  circle  of  the  earth.  Theoretically,  therefore,  if  all  the 
meter  bars  were  lost  this  unit  of  measurement  could  be  reproduced  with 
approximate  fidelity.  In  the  same  way  it  is  theoretically  possible  to 
reproduce  the  diphtheria  antitoxic  unit  in  consideration  of  that  fact  that 
it  has  just  200  combining  units. 

The  test  by  which  the  strength  of  antitoxin  is  measured  is  a  physio- 
logical one,  and  depends  upon  the  neutralization  of  the  toxin  by  the 
antitoxin.  This  neutralization  can  only  be  determined  by  injecting  the 
toxine-antifoxin  mixtures  into  guinea-pigs  and  noting  the  results.  The 
unit  for  measuring  the  strength  of  diphtheria  antitoxin  is  a  measure  of 
physiologic  strength,  not  of  quantity. 

In  all  the  early  work  on  this  subject  the  toxine  was  used  as  a  basis 
for  measuring  the  strength  of  the  antitoxin,  but  as  the  toxine  is  a  much 
more  complex  substance  than  the  antitoxin,  and  as  it  is  less  stable,  ac- 
curate results  were  not  possible.  Ehrlich  showed  that  the  antitoxin  under 
certain  conditions  was  permanent  both  in  power  of  chemically  combining 
with  and  physiologically  neutralizing  the  toxine.  One  antitoxin,  however, 
cannot  be  compared  with  another  antitoxin  directly.  This  can  only  be 
done  through  the  toxine. 

From  a  practical  standpoint,  the  following  illustration  of  a  test  will 
give  a  clear  conception  as  to  how  the  unit  of  strength  of  a  serum  is 
determined. 

Example  of  a  Test. — It  is  first  necessary  to  obtain  our  official  yard- 
stick. This  inay  be  done  by  applying  to  the  Hygienic  Laboratory  in 
Washington,  where  the  standard  serum  is  kept  in  a  dry  powdered  form 
in  vacuum  tubes  under  the  influence  of  pentaphosphoric  acid  in  a  cold 
place  and  carefully  preserved  from  the  light.  This  powder  is  dissolved, 
carefully  tested,  and  sent  to  the  ajaplicant  in  a  glycerinated  solution. 
Each  cubic  centimeter  of  a  certain  dilution  of  this  standard  serum 
contains  just  1  unit.  Before,  however,  we  can  measure  the  potency  of 
an  antitoxic  serum  of  unknown  strength  it  is  first  necessary  to  standardize 
a  toxine.  This  is  done  by  mixing  one  unit  of  the  standard  antitoxic 
serum  with  varying  quantities  of  the  toxine,  as  shown  in  table  on  p.  433. 

From  this  series  we  learned  that  one  unit  contains  just  sufficient  anti- 
toxin to  neutralize  0.16  c.  c.  of  the  toxine.  This  is  known  as  the  Lq 
dose.^  By  the  Lq  dose,  then,  is  meant  that  quantity  of  poison  which 
just  neutralizes  or  saturates  one  immunity  unit  as  shown  at  the  necropsy 
done  48  hours  after  the  subcutaneous  injection  of  the  mixture  into  the 
guinea-pig.  The  reaction  at  the  site  of  inoculation  at  this  examination 
must  be  hardly  noticeable. 

In  the  above  illustration  the  L  dose  of  this  toxine  is  just  0.21  c.  c. 
By  the  L      dose  is  meant  the  smallest  quantity  of  poison  that  will  neu- 

^  L  stands  for  Limit.  Lq  stands  for  the  limit  of  no  reaction,  and  L-)-  the 
limit  of  acute  death. 


STANDAEDIZATION    OF   ANTITOXIC    SEEA  433 

Mixtures   of   Antitoxic    Serum    and 
Toxine  Injected  Subcutaneously 

into  Guinea-Pigs.  Result. 

1  immunity  unit  -|-  0.14  c.  c.  toxine  =  No  reaction. 
"  ''     -L  0.15     "         "      =  No  reaction. 

"  "     -|-  0.16     "         "      =  Slight  congestion  at  site  of  injection. 

[This  is  the  L^    dose.] 
"  "     -j-  0.17     "         "      =  Apparent  reaction  at  site  of  injection. 

"  "     -[-  0.18     "         "      =  Injection  and  edema  at  site. 

"  "     _|_  0.19     "         "      =  Injection    and    edema    at    site ;    late 

paralysis. 
"  "     -j-  0.20     "         "      =  Sometimes  death  in  5  or  6  days,  some- 

times late  paralysis. 
"  "     -(-  0.21     "         "      =  Always  causes  acute  death  about  the 

fourth  day.    [This  is  the  L  ,  dose.] 
"  "     _|_  0.22     "         "      =  Acute    death    usually    on   second   or 

third  day. 
"  "     _|_  0.23     "         "      =  Acute  death  on  second  day. 

tralize  one  immunity  unit  plus  a  quantity  necessary  to  kill  the  animal 
on  the  fourth  day.  The  L ,  dose  is  the  test  dose  which  is  used  to  deter- 
mine the  strength  of  our  unknown  antitoxic  serum,  as  follows : 

The  L_|_  (or  Test  Dose  of  Toxin)  -j-  Varying 

Amounts  of  Antitoxin  Injected  into  Results. 

Guinea-Pigs. 
0.21  c.  c.  toxine  -|-  1/150  c.  c.  antitoxic  serum  =  No  effect. 

+  1/175     "  "  "       =  No  effect. 

-j-  1/200     "  "  "       =:  Late  paralysis. 

-1-1/225     "  "  "       =  Late  paralysis. 

-)-  1/250     "  "  "       =  Dies  4th  day. 

-j-  1/275     "  "  "      =  Dies  3d  day. 

4-1/300     "  "  "       =  Dies  2d  day. 

From  this  series  it  is  evident  that  1/250  c.  c.  of  the  serum  contains 
that  amount  of  antitoxin  which  will  neutralize  the  toxine  in  the  test 
dose,  leaving  sufficient  free  poison  to  kill  the  animal  on  the  fourth  day. 
The  serum,  therefore,  contains  one  antitoxic  unit  in  1/250  c.  c.  of  serum. 
One  c.  c.  of  the  serum  would,  therefore,  contain  250  units. ^ 

Standardization  of  Tetanus  Antitoxin. — There  are  four  methods  of 
measuring  the  strength  of  tetanus  antitoxin:  (1)  the  German  method 
described  by  Behring;  (2)  the  French  method  described  by  Eoux;  (3) 
the  Italian  method  after  Tizzoni,  and  (4)  the  American  method  estab- 

For  the  details  for  carrying  out  these  tests  the  reader  is  referred  to  the 
Hygienic  Laboratory  Bulletin  No.  21  upon  "The  Immunity  Unit  for  Standard- 
izing Diphtheria  Antitoxin."  by  M.  J.  Rosenau,  which  contains  the  official  descrip- 
tion and  details  of  the  process  and  its  theoretical  considerations. 


434  IMMUNITY    . 

lished  by  Eosenau  and  Anderson.^  European  standards  are  admitted  to 
be  unsatisfactory  and  for  the  most  part  not  accurate.  Further,  they 
are  complicated  and  difficult  to  carry  out.  The  American  method,  which 
has  been  made  the  official  government  standard  for  this  and  other  coun- 
tries, commends  itself  for  its  simplicity,  directness,  and  precision. 

The  tetanus  antitoxic  unit  is  based  upon  the  neutralizing  value  of  an 
arbitrary  quantity  of  antitoxic  serum  preserved  under  special  conditions 
to  prevent  deterioration  in  the  Hygienic  Laboratory  of  the  Public  Health 
Service.  This  arbitrary  quantity  now  contains  ten  times  the  amount  of 
tetanus  antitoxin  necessary  to  neutralize  somewhat  less  than  100  minimal 
lethal  doses  of  a  standard  toxine  for  a  350-gram  guinea-pig.  That  is, 
0.1  of  a  unit  mixed  with  100  minimal  lethal  doses  of  the  standard  toxine 
contains  just  enough  free  poison  in  the  mixture  to  kill  the  guinea-pig 
in  four  days  after  subcutaneous  injection. 

The  official  definition  of  a  tetanus  antitoxic  unit  is  the  following: 
The  immunity  unit  for  measuring  the  strength  of  tetanus  antitoxin 
shall  be  ten  times  the  least  quantity  of  antitetanic  serum  necessary  to 
save  the  life  of  a  350-gram  guinea-pig  for  96  hours  against  the  official 
dose  of  a  standard  toxine  furnished  by  the  Hygienic  Laboratory  of  the 
Public  Health  and  Marine  Hospital  Service. 

The  standardization  of  tetanus  antitoxin  does  not  differ  radically 
from  the  standardization  of  diphtheria  antitoxin.  The  toxins  and  anti- 
toxins are  mixed  and  the  mixture  injected  into  guinea-pigs.  While,  how- 
ever, the  unit  is  based  upon  the  neutralizing  value  of  an  arbitrary  quan- 
tity of  antitoxic  serum,  the  antitoxin  is  not  issued  for  a  basis  of  com- 
parison, as  in  the  case  of  diphtheria.  A  stable  precipitated  toxine,  the 
test  dose  of  which  has  been  carefully  determined,  is  issued  to  other  labora- 
tories for  the  purpose  of  testing. 

The  value  of  an  unknown  serum  is  measured  directly  from  this 
standard  precipitated  toxine,  the  L  ,  ,  or  test  dose,  of  which  is  stated. 
The  L , ,  or  test  dose,  of  the  particular  toxine  now  dispensed  by  the  gov- 
ernment contains  just  100  minimal  lethal  doses  for  a  350-gram  guinea- 
pig.  This  particular  toxine  is  very  stable  and  has  not  changed  appre- 
ciably in  eight  years.  As  soon  as  it  alters  or  is  exhausted  the  next  toxine 
that  will  be  issued  may  contain  more  or  less  than  100  minimal  lethal 
doses,  but  the  test  dose  will  contain  precisely  the  same  neutralizing 
power. 

The  tetanus  antitoxic  unit  may  be  better  understood  from  an  exam- 
ple of  a  test. 

An  Example  of  a  Test. — Carefully  tare  a  weighing  bottle,  then 
add  apj)roximately  20  to  50  mg.  of  the  dried  poison.  Again  carefully 
weigh.     Dissolve  the  toxine  in  the  weighing  bottle  with  salt  solution 

^Hygienic  Laboratory  Bulletin  No.  43,  P.  H.  &  M.  H.  Service,  Washington, 
March,  1908. 


STANDARDIZATION    OF    ANTITOXIC    SERA 


435 


(0.85)  in  the  proportion  of  0.1  gram  of  the  dried  poison  to  166.66  c.  c. 
of  the  salt  solution.  This  proportion  is  used  for  the  reason  that  each 
cubic  centimeter  of  this  solution  will  represent  0.0006  gm.  of  the  orig- 
inal dried  poison  (=  100  MLD's).  This  proportion  is  taken  because 
it  is  very  convenient  in  measuring  out  the  test  dose,  which  represents 
1  c.  c.  of  the  solution.     Thus : 

44.5692  gm.,  bottle  -f-  toxine. 
44.5300  gm.,  bottle. 


.0392  gm.,  toxine. 
0.1  gm.  :  166.66  c.  c.  : :  0.0392  :  x. 
X  =  65.33  c.  c. 

In  other  words,  if  the  quantity  of  toxine  placed  in  the  weighing 
bottle  should  weigh,  as  in  this  instance,  just  0.0392  gm.,  carefully  deliver 
from  an  accurately  graduated  burette  just  65.33  c.  c.  salt  solution  into 
the  weighing  bottle ;  and,  as  before  stated,  each  cubic  centimeter  of  this 
solution  will  be  the  L  !^  or  test  dose. 

Now  dilute  the  serum  of  unknown  value  in  accordance  with  the  table 
of  dilutions,  and  mix  aliquot  parts  of  the  serum  with  the  test  dose  of 
toxine,  as  follows : 


No.  of 
guinea-pig 


1 

2 
3 
4 
5 


Weight  of 

guinea-pig 

(grams) 


350 
350 
350 
350 
350 


Subcutaneous  injection  of  a 
mixture  of — 


Toxine  (test  dose) 


Gram. 

0.0006 
.0006 
.0006 
.0006 
.0006 


Antitoxin 


C.  C. 
0.001 

.0015 
.002 
.0025 
.003 


Time  of  death 


2  days,  4  hours. 
4  days,  1  hour 
Symptoms. 
Slight  symptoms. 
No  symptoms. 


According  to  this  series  the  guinea-pig  which  received  the  mixture 
containing  0.0015  c.  c.  of  the  serum  died  in  four  days  and  one  hour. 
Therefore,  0.0015  c.  c.  of  the  serum  contains  one-tenth  of  an  immunity 
unit,  as  the  unit  has  been  defined  as  ten  times  the  least  amount  of  anti- 
tetanic  serum  necessary  to  save  the  life  of  a  350-gram  guinea-pig  96 
hours  against  the  official  test  dose.  This  serum  would,  therefore,  contain 
just  66  units  per  c.  c. 

In  order  to  obtain  reliable  and  comparable  results,  it  is  necessary 
to  take  into  account  all  the  factors  concerned — the  composition  of  the 
poisons,  their  concentration,  the  diluting  fluid,  length  of  time  the  mix- 
tures are  allowed  to  stand,  the  site  of  inoculation,  etc.,  in  accordance 
with  directions  in  the  official  methods. 


436  IMMUNITY 


PHAGOCYTOSIS 

Metchnikoff  gave  us  the  first  physical  explanation  of  immunity 
through  his  brilliant  studies  upon  phagocytosis.  Metehnikofi'  was  a  biol- 
ogist, and  as  a  result  of  his  stimulating  observations  upon  the  phago- 
cytes in  all  the  orders  of  the  animal  kingdom  lie  contributed  much 
to  our  knowledge,  not  alone  of  immunity,  but  to  our  fundamental  knowl- 
edge of  nutrition  and  inflammation.  The  ingenuity  and  fertility  of  his 
views  caused  a  flood  of  work  from  others  upon  these  basic  siibjects  in 
medical  biology. 

Phagocytosis  is  a  process  common  to  all  cells  having  amebic  motion. 
A  phagocyte  is  any  cell  capable  of  absorbing  particulate  matter  into 
its  substance.  The  process  is  best  seen  with  an  ameba  under  the  micro- 
scope. 

For  a  clear  understanding  of  phagocytosis  it  is  necessary  to  consider 
three  phases  of  the  process:  (1)  the  approach,  (2)  the  engulf ment,  and 
(3)  the  digestion. 

The  approach  or  ch  emotaxis  is  a  phenomenon  which  is  displayed 
by  almost  all  motile  and  unicellular  organisms,  whether  animal  or  vege- 
table, as  well  as  by  the  leukocytes.  It  manifests  itself  by  a  movement 
of  the  unicellular  organism  or  the  phagocytic  cell  toward  the  particle  and 
seems  to  be  a  response  to  a  chemical  stimulus.  Chemotaxis  is  said  to  be 
positive  when  the  leukocytes  are  quickly  and  energetically  attracted  to 
a  substance,  and  negative  when  this  attraction  is  lacking.  There  is 
considerable  doubt  whether  there  is  true  negative  chemotaxis  in  the  sense 
of  repulsion.  The  degree  of  chemotaxis  possessed  by  any  substance  may 
readily  be  determined  by  placing  it  in  a  capillary  tube  closed  at  one  end 
and  then  inserting  the  open  end  of  the  tube  into  the  tissue  of  an  animal 
or  into  a  fluid  containing  active  phagocytes.  If  the  substance  has  positive 
chemotactic  power  the  phagocytes  soon  approach  the  free  end  of  the 
capillary  tube,  which  they  enter;  if  the  substance  has  negative  chemo- 
tactic power  the  phagocytes  are  not  attracted  and  do  not  enter  the  capil- 
lary tube.  As  Emery  points  out,  the  leukocytes  are  in  many  cases  at- 
tracted into  an  infected  area  to  their  own  undoing,  and  it  must  not  be 
forgotten  that  "even  in  inflammatory  processes  Avhich  are  mild  in  nature 
and  favorable  in  result  the  number  of  leukocytes  which  may  be  killed  in 
the  conflict  is  enormous.  The  leukocytes  are  not  independent  protozoa 
inhabiting  the  blood  and  tissues,  but  an  integral  part  of  the  organism. 
It  is  to  the  advantage  of  the  latter  that  the  former  should  be  attracted 
at  once  to  the  seat  of  invasion,  and  hence  the  processes  of  evolution  have 
led  to  the  development  of  this  function  in  the  nomadic  cells  of  the  body. 
These  are  extraordinarily  susceptible  to  chemotactic  influences.  They 
seem  to  be  attracted  by  any  deviation  from  the  normal  situation  of  the 


PHAGOCYTOSIS  437 

tissues  and  fluids — a  slight  injury,  a  liemorrhagc,  the  presence  of  a  poison, 
or  a  foreign  body  of  any  sort,  or  any  dead  or  useless  tissue — and  the  leuko- 
cytes are  immediately  attracted  into  the  area  affected.  The  more 
we  regard  the  process  the  more  we  must  regard  it  as  one  of  the 
most  exquisite  examples  of  means  to  ends  met  with  in  the  animal 
economy." 

The  eiifjulfment  of  the  bacteria  may  readily  be  studied  in  amebae 
in  their  free  living  stage.  The  protoplasm  of  the  ameba  is  thrown  out 
in  the  form  of  pseudopodia;  these  encircle  the  particle,  which  soon 
appears  within  the  substance  of  the  ameba.  The  engulfment  of  particles 
by  the  leukocytes  and  other  cells  is  precisely  the  same. 

The  digestion  within  the  cell  is  entirely  comparable  to  gastric  diges- 
tion in  higher  animals.  It  is  now  known  that  active  proteolytic  ferments 
dissolve  the  albuminous  particles,  and  that  this  takes  place  in  an  acid 
medium  may  be  demonstrated  by  the  use  of  delicate  indicators,  such  as 
neutral  red. 

The  phagocytes  may  take  up  and  digest  either  live  or  dead  bacteria; 
they  are  not  simply  scavengers.  They  engulf  particles  of  all  kinds,  both 
organic  and  inorganic.  Thus,  in  anthracosis  the  particles  of  coal  are 
mainly  carried  and  contained  in  the  phagocytic  cells.  The  phagocytes 
play  a  similar  role  with  the  malarial  pig-ment,  with  the  granules  of  pig- 
ment left  after  a  hemorrhage,  and  with  other  foreign  particles  in  the 
body.  Phagocytes  are  also  enabled  to  absorb  colloidal  substances  and 
fluids  as  well  as  particulate  matter.  They  are  enabled  to  dispose  of  com- 
paratively large  masses  by  removing  it  piecemeal.  Thus,  the  "core"  of 
boils  is  gradually  removed  mainly  by  the  phagocytes.  Catgut  and  silt 
ligatures  are  similarly  removed  and  the  absorption  of  the  tadpole's  tail  is 
disposed  of  through  the  same  process. 

Metchnikoff  divided  the  phagocytes  into  free  and  fixed,  macrophages 
and  microphages. 

The  free  phagocytes  are  the  leukocytes,  lymphocytes,  and  other  blood 
cells,  as  the  myelocytes  from  the  bone  marrow.  The  fixed  phagocytes 
are  the  connective  tissue  cells  and  endothelial  cells.  The  free  phago- 
cytes, according  to  Metchnikoff,  play  the  more  important  role. 

The  microphages  or  microcytes  are  the  mononuclear  leukocytes,  the 
polymorphonuclear  leukocytes,  and  the  Avandering  connective  tissue  cells. 
The  macrophages  or  macrocytes  are  the  large  lymphocytes,  the  mononu- 
clear pulp  cells  of  the  spleen  and  bone  marrow,  endothelial  cells  of  the 
large  vessels,  and  Kupfer's  stellate  cells  of  the  liver.  The  microphages 
play  an  active  part  in  all  acute  infections.  They  are  the  first  to  come 
in  the  field  and  for  the  most  part  are  vegetarians,  that  is,  they  take  up 
bacteria  especially.  The  macrophages,  on  the  other  hand,  are  carnivorous, 
engulfing  other  cells  and  protozoon  parasites,  and  are  especially  concerned 
in  chronic  inflammations,  such  as  tuberculosis  and  leprosy,  rather  than 


438  IMMUNITY 

in  the  acute  processes.  These  distinctions  l)etwcen  the  free  and  fixed 
phagocytes,  the  microphages  and  macrophages,  are  entirely  arbitrary. 
All  the  leukocytes  have  the  power  of  phagocytosis,  though  in  varying 
degree.  This  is  readily  seen  in  an  opsonic  preparation  or  in  an  examina- 
tion of  a  smear  of  gonorrheal  pns,  when  some  of  the  polymorphonuclear 
leukocytes  will  be  loaded  with  the  cocci  while  others  contain  few  or  none. 
The  small  phagocytes  (microcytes)  are  able  to  engulf  protozoa  and 
animal  cells  as  well  as  bacteria. 

Metchnikoff  has  insisted  since  the  beginning  of  his  studies  upon 
phagocytosis  that  this  process  plays  an  important,  if  not  the  sole,  role 
in  immunity.  He  conceives  that  a  true  battle  takes  place  between  the 
cells  and  the  invading  germs.  When  phagocytosis  is  active  and  suc- 
cessful, immunity  is  the  result.  If  phagocytosis  is  absent,  or  the  phago- 
cytes are  unsuccessful,  the  result  is  susceptibility  instead  of  immunity. 
Metchnikoff  first  studied  the  protective  power  of  the  phagocytes  in  a  fresh 
water  crustacean,  the  daphnia,  which,  from  its  transparency  and  small 
size,  is  a  very  suitable  creature  for  observation.  He  found  that  the  daph- 
nia is  subject  to  a  disease  due  to  the  invasion  of  its  body  cavity  by  the 
spores  of  a  yeast  (Monospora),  and  that  if  these  spores  gain  access  in 
large  numbers  they  multiply,  form  into  mature  organisms,  and  finally  kill 
their  host.  When,  however,  a  few  spores  gain  access  he  found  the  leuko- 
cytes of  the  daphnia  approach  them,  form  a  wall  around  them,  and  finally 
digest  and  destroy  them.  It  is  obvious,  therefore,  that  the  immunity  of 
the  daphnia  to  this  infection  depends  upon  the  activity  of  its  leukocytes. 
Analogous  instances  are  found  in  many  other  animals,  including  man. 
In  the  streptococcus  infections  particularly  Metchnikoff  believed  their 
virulence  depended  upon  the  absence  of  phagocytic  action. 

It  soon  became  evident  to  Metchnikoff  himself  that  the  mechanism 
of  immunity  was  a  much  more  complicated  process  than  could  be  ac- 
counted for  simply  by  the  number  and  physical  activity  of  the  phago- 
cytes. The  simple  act  of  phagocytosis  alone  could  not  explain  all  the 
phenomena.  It,  therefore,  became  necessary  to  study  the  processes  of 
digestion  and  the  products  of  excretion  of  the  phagocytes.  It  soon  be- 
came evident  that  the  digestive  power  of  the  phagocytes  is  a  very  power- 
ful one,  and  substances  usually  deemed  entirely  insoluble  may  be  gradu- 
ally removed  by  their  action.  Metchnilcoff  considered  two  of  these  sub- 
stances to  be  concerned  in  immunity :  the  microcytase  and  the  macro- 
cytase. 

The  microcytase  is  a  ferment-like  substance  obtained  from  the  micro- 
cytes. It  is  thermolabile  and  corresponds  in  all  essential  respects  to  the 
alexin  of  Buchner  or  the  complement  of  Ehrlich. 

The  macrocytase  is  a  thermostable  substance  obtained  from  the  macro- 
cytes.  It  is  concerned  with  specific  acquired  immunity.  The  macrocyte 
fastens  itself  to  the  bacteria,  hence  was  called  by  Metchnikoff  the  fixator. 


OPSONINS  439 

It  is  similar  in  all  essential  respects  to  the  "substance  sensibilitrice"  of 
Bordet,  or  the  amboceptor  of  Ehrlich. 

Buchner,  as  well  as  most  other  unprejudiced  students  in  immunol- 
ogy, takes  the  middle  ground  between  the  doctrines  of  the  cellular  theory 
represented  by  Metchnikoff  and  his  school  and  the  doctrines  of  the  hu- 
moral theory  represented  by  Ehrlich.  It  now  seems  quite  evident  that 
both  the  cells  and  the  body  fluids  play  an  important  role  in  the  mechanism 
of  immunity.  It  is  also  equally  evident  that  the  mechanism  of  immunity 
differs  widely  with  different  infections;  in  some  phagocytosis  plays  a 
dominant  part;  in  others  it  seems  that  the  fluids  of  the  body  are  chiefly 
concerned.  It  must  not  be  forgotten  that  even  where  the  fluids  of  the 
body  are  the  chief  actors  the  antibodies  are  probably  in  all  cases  derived 
from  the  cells.  Just  what  cells — whether  the  fixed  tissue  cells  or  the 
free  phagocytes — are  chiefly  concerned  in  the  production  of  these  anti- 
bodies is  not  quite  clear. 

All  observers  are  agreed  upon  one  thought,  and  that  is,  fundamen- 
tally immunity  is  closely  allied  to  the  processes  of  cell  nutrition.  The 
receptors  of  Ehrlich  are  the  mouths  of  the  cells  for  food.  The  phago- 
cytosis of  Metchnikoff  is  primarily  a  mechanism  by  which  cells  possess- 
ing amebic  motion  obtain  their  food.  Anaphylaxis,  which  offers  another 
explanation  of  immunity  to  certain  infections,  deals  with  the  funda- 
mental problems  of  protein  metabolism.  It  is,  therefore,  plain  that  any 
experimental  research  that  gives  a  deeper  insight  into  protein  metabolism 
as  well  as  the  more  direct  researches  in  immunology  has  a  fundamental 
bearing  upon  the  prevention  and  cure  of  disease. 


OPSONINS 

The  name  opsonin  (opsono:  1  cater  for,  I  prepare)  is  given  to  sub- 
stances which  occur  in  the  blood  and  which  have  the  power  of  prepar- 
ing bacteria  and  other  cells  for  ingestion  by  the  leukocytes.  The  opsonins 
combine  with  the  bacteria  and  in  that  way  prepare  them  for  being  taken 
up  more  easily  by  the  phagocytic  cells.  In  the  absence  of  opsonins, 
phagocytosis  does  not  take  place,  and  their  great  importance  is,  therefore, 
at  once  manifest.  There  is  now  no  doubt  concerning  the  existence  of 
these  substances,  and  the  brilliant  work  of  Wright  has  stimulated  a  flood 
of  researches  which  have  thrown  much  light  upon  this  chapter  in  im- 
munology. 

The  opsonins  are  normally  present  in  the  blood  or  may  be  increased 
or  diminished  in  amount  by  the  injection  of  bacteria  or  appropriate 
antigen.  The  opsonins  are  specific,  that  is,  the  blood  serum  may  contain 
opsonins  which  prepare  staphylococci  for  the  phagocytes,  but  may  contain 
no  suitable  substance  to  prepare  streptococci,  tubercle  bacilli,  or  some 


440  IMMUNITY 

other  microorganism.  The  opsojiins  are  probal)ly  similar  to  the  bacterio- 
tropins;  their  chemical  nature,  however,  in  common  with  other  anti- 
bodies, is  not  understood. 

The  Opsonic  Index. — Sir  Almroth  Wright  has  modified  Leishmann's 
method  for  measuring  the  opsonic  power  of  the  blood  serum,  but  the 
method  is  somewhat  complicated  and  gives  variable  results  even  in  the 
hands  of  trained  workers.  It  may  be  questioned  whether  any  of  the 
tests  now  in  use  are  a  true  index  of  the  amount  of  opsonins  in  the  serum, 
although  they  may  be  taken  to  indicate  roughly  the  measure  of  their 
activity.  The  opsonic  index  has  been  especially  used  as  a  guide  to 
vaccine  therapy  rather  than  in  preventive  medicine.  If,  however,  we  had 
a  satisfactory  and  ready  method  by  which  the  specific  opsonins  of  the 
blood  could  be  measured  so  that  deficiencies  could  be  readily  determined 
and  strengthened,  we  would  theoretically  at  least  have  a  valuable  addition 
to  prophylaxis. 

LYSINS 

Lysins  are  substances  that  have  the  power  of  disintegrating  or  dis- 
solving cells  or  other  organized  structures.  Those  that  dissolve  bacteria 
are  known  as  the  bacteriolysms,  those  that  dissolve  red  blood  cells  are 
called  hemolysins,  those  that  dissolve  epithelial  or  other  body  cells  are 
called  cytolysins  or  cytotoxins.  The  lysins  in  themselves  are  not  poison- 
ous, but  through  their  action  they  may  liberate  or  generate  toxic  sub- 
stances and  thus  play  an  important  role  not  only  in  the  pathogenesis  of 
many  infectious  diseases  and  diseased  states,  but  also  in  their  cure  and 
prevention. 

jSTormally  the  blood  possesses  bactericidal  properties,  and  it  is  be- 
lieved that  this  is  almost  entirely  due  to  its  power  of  dissolving  the  bac- 
terial cells.  The  bacteriolytic  property  of  normal  blood  serum  is  not 
specific,  whereas  the  bacteriolysins  induced  through  special  processes  by 
immunization  are  strictly  specific.  The  fact  that  the  blood  has  the  power 
of  resisting  decomposition  longer  than  other  animal  fluids  was  known  to 
Hunter  before  the  era  of  bacteriology.  It  was  also  early  known  that 
this  property  of  the  blood  diminishes  spontaneously  after  it  Avas  shed 
and  could  be  destroyed  by  heat — about  55°  C.  The  bacteriolytic  sub- 
stances in  the  blood  were  first  studied  by  Buchner  and  Nuttall,  who  called 
them  alexins.  When  it  was  discovered  that  the  blood  possesses  marked 
powers  of  destroying  bacteria  the  conclusion  was  naturally  drawn  that 
herein  lies  the  explanation  of  immunity.  It  was  soon  learned,  however, 
that,  though  the  blood  of  certain  animals  may  possess  marked  bactericidal 
properties,  nevertheless  they  are  very  susceptible;  and,  further,  that  the 
power  to  kill  bacteria  is  much  more  marked  in  the  serum  than  in  the 
circulating  blood  in  the  animal.     Thus,  according  to  Lubarsch,  16,000 


LYSINS  441 

virulent  bacilli  will  kill  a  rabbit  if  injected  intravenously;  that  is,  the 
blood  within  the  body  has  not  the  power  of  killing  this  number,  yet  1  c.  c. 
of  fresh  blood  serum  will  destroy  this  number  or  even  more  iu  a 
test  tube. 

Eabbits  are  very  susceptible  to  anthrax,  although  the  blood  serum 
of  these  animals  possesses  marked  bactericidal  properties  for  the  an- 
thrax bacillus;  on  the  other  hand,  the  dog  is  very  resistant  to  anthrax, 
despite  the  fact  that  its  blood  serum  is  very  slightly  bactericidal. 

The  bacteriolysins  were  discovered  by  Eichard  Pf  eiff er  ^  in  his  at- 
tempt to  actively  immunize  animals  against  cholera  by  the  injection 
of  live  cultures.  He  observed  that  the  cholera  organisms  were  disin- 
tegrated and  dissolved  in  the  peritoneal  cavity  of  the  immunized  animals. 
This  gave  rise  to  what  is  now  known  as  Pfeiffer's  phenomenon,  which,  on 
account  of  its  importance,  must  be  considered. 

Pfeiffer's  Phenomenon. — Guinea-pigs  are  immunized  by  the  subcu- 
taneous injection  of  increasing  doses  of  a  cholera  culture  about  once  a 
week  until  they  are  able  to  withstand  large  amounts  of  a  fresh  viru- 
lent strain.  This  usually  required  at  least  three  or  four  injections. 
Some  of  the  live  microorganisms  are  now  injected  into  the  peritoneal 
cavity  of  the  immunized  animal,  and  from  time  to  time  minute  drops 
of  this  injected  material  with  the  peritoneal  exudate  are  withdrawn  by 
means  of  capillary  tubes  and  examined  under  the  microscope.  It  will 
be  found  that  the  bacteria  previously  actively  motile  soon  lose  their 
power  of  motion  and  die.  They  then  become  somewhat  swollen  and 
agglutinate  into  balls  or  clumps,  which  gradually  become  paler  and 
paler.  The  disintegrating  bacterial  cells  become  granular  and  finally 
are  completely  dissolved  in  the  peritoneal  fluid.  This  process  usually 
takes  about  twenty  minutes,  provided  the  animal  has  been  sufficiently 
highly  immunized.  For  a  control,  a  like  quantity  of  the  cholera  culture 
is  injected  into  the  peritoneal  cavity  of  a  normal  guinea-pig.  In  this 
case  the  microorganisms  are  not  immobilized,  agglutinated,  or  dissolved. 
Further,  the  immunized  animal  remains  unaffected  while  the  control  ani- 
mal dies  as  a  result  of  the  infection.  This  reaction  is  specific,  that  is, 
a  guinea-pig  immunized  against  cholera  will  immobilize,  agglutinate,  and 
dissolve  only  the  cholera  vibrios;  a  guinea-pig  immunized  with  typhoid 
will  act  upon  typhoid  and  not  upon  cholera. 

It  was  soon  discovered  by  Bordet  that  this  reaction  takes  place  not 
only  in  the  peritoneal  cavity  of  the  immunized  animal,  but  will  occur 
in  the  test  tube  when  the  peritoneal  exudate  or  the  blood  serum  of 
tlie  immunized  animal  is  mixed  with  the  cholera  organisms.  It  was 
through  a  study  of  this  reaction  that  Pfeiffer  and  Kolle  and  later  Gruber 
and  then  Widal  discovered  and  described  the  ability  of  blood  serum  to 
clump  or  agglutinate  bacteria.     It  seems  evident  that  this  power  of  the 

""Zeit.  f.  Hyg.,  Vol.  XVIII,  and  Deutsche  med.  Woclien.,  1896,  pp.  97,  119. 


443  IMMUNITY 

blood  serum  or  the  peritoneal  exudate  of  the  immunized  guinea-pig  is  an 
important  factor  in  the  mechanism  of  its  immunity. 

Nature  of  Lysins. — Bacteriolysins  are  absolutely  distinct  from  anti- 
toxins and  agglutinins.  Even  when  these  three  substances  coexist  they 
may  be  distinguished  one  from  the  other  through  physical,  chemical,  or 
biological  tests.     Nothing  is  known  as  to  their  chemical  composition. 

Any  general  statement  concerning  the  thermal  death  point  or  other 
characters  of  the  lysins  must  be  misleading,  from  the  fact  that  we  now 
know  that  lytic  action  is  always  due  to  a  combination  of  two  substances : 
one  stable,  the  other  unstable;  one  readily  destroyed  by  heat,  the  other 
quite  resistant  to  heat.  This  important  observation  was  made  by  Bordet, 
who  was  the  first  to  show  that  two  substances  are  necessary  for  the  phe- 
nomenon of  bacteriolysis.  He  considered  that  one  of  these  substances 
sensitized  the  bacteria,  and,  therefore,  called  it  the  "substance  sensibili- 
trice";  this  substance  is  thermostable.  The  other  substance,  which  is 
thermolabile,  he  continued  to  call  alexin.  Bordet  found  that  all  the 
essential  features  of  bacteriolysis  could  be  reproduced  exactly  if  red  blood 
corpuscles  were  substituted  for  the  bacteria.  It  was  this  analogy  between 
bacteriolysis  and  hemolysis  that  led  Ehrlich  to  an  investigation  of  the 
latter  phenomenon,  and  his  researches  led  to  much  new  light  upon  the 
subject.  Ehrlich  introduced  new  names  for  the  substances  which  Bordet 
has  shown  to  be  necessary  for  the  phenomenon,  and  applied  his  side-chain 
theory  to  explain  the  reaction. 

Many  names  have  been  given  to  the  two  substances  which  take  part 
in  lysis.  The  thermostable  substance  has  been  called  substance  sensibili- 
trice,  or  simply  sensibilitrice,  immune  body,  amboceptor,  fixator,  inter- 
mediary body,  interbody,  philocytase,  immunisin,  desmon,  copula  and 
preparator;  while  the  thermolabile  substance  has  been  called  the  alexin, 
complement,  addiment,  and  cytase.  We  shall  speak  of  the  first  as  the 
immune  body  and  the  second  as  the  complement. 

One  of  the  remarkable  facts  connected  with  the  phenomenon  of  the 
lytic  poisons  is  that  the  poison  itself  (complement)  is  normally  pres- 
ent in  the  blood.  This  substance  is  a  fragile  body,  readily  destroyed  at  a 
moderate  temperature — 55°  C.  .  It  disappears  spontaneously  from  the 
serum  when  kept  for  a  few  days ;  it  is  destroyed  by  acids  and  alkalis  and 
is  not  specific  in  its  action.  Complement  appears  to  be  formed  by  the 
breaking  down  of  the  leukocytes,  which  accounts  for  the  fact  that  blood 
serum  after  clotting  is  much  more  potent  than  the  whole  blood ;  further, 
complement  is  absent  from  fluids  containing  no  leukocytes,  such  as  the 
aqueous  humor. 

According  to  Ehrlich,  the  immune  body  has  two  combining  affinities, 
and,  therefore,  he  called  it  the  amboceptor.  It  unites  on  the  one  hand' 
with  the  complement  and  on  the  other  with  the  receptor  of  the  cell. 
Bordet,  howcA^er,  considers  that  the  cell  unites  directly  but  separately  with 


HEMOLYSIS  443 

both  the  complement  and  the  immune  body.  The  immune  body  is  stable 
and  specific ;  it  is  more  stable  than  the  agglutinins  or  even  the  antitoxins. 
It  is  not  injured  by  heating  to  60°  C,  it  is  weakened  at  70°  C,  and 
finally  destroyed  by  prolonged  exposure  at  this  temperature.  It  is  called 
the  immune  body  because,  according  to  Ehrlich's  views,  immunity  can 
only  be  obtained  through  it  on  account  of  its  specific  reaction. 

In  bacteriolytic  immunity  it  is  the  immune  body  rather  than  the  com- 
plement that  is  increased. 

Just  what  service  the  lysins  are  in  the  mechanism  of  immunity  is 
not  clear.  Eecent  studies  indicate  that  they  may  at  times  be  harm- 
ful as  well  as  useful.  Thus,  by  dissolving  the  bacterial  cell  they  have 
the  power  of  releasing  "endotoxins.'^ 

The  studies  upon  anaphylaxis  have  thrown  much  collateral  light  upon 
the  probable  action  of  the  bacteriolysins  in  the  pathogenesis,  cure,  and 
prevention  of  disease.  When  the  bacteria  are  dissolved  within  the  body 
the  protein  matter  which  they  contain  is  set  free.  This  may  not  be 
poisonous  in  itself,  that  is,  may  not  have  any  of  the  properties  ordinarily 
attributed  to  the  endotoxins.  This  foreign  bacterial  protein,  however, 
may  sensitize  the  organism  so  that  the  second  time  the  protein  is  liberated 
it  may  cause  a  reaction  which  may  account  for  some  of  the  pathogenic 
effects  and  symptoms  of  the  disease. 

Buxton  and  Coleman  explain  the  pathogenesis  of  typhoid  fever  as 
largely  due  to  a  solution  of  the  typhoid  bacilli  within  the  body,  and  it 
is  probable  that  in  pneumonia  and  other  infections  a  like  action  takes 
place.  An  organism  that  has  once  reacted  to  a  particular  bacterium 
remains  immune  so  long  as  it  possesses  an  altered  power  of  reaction, 
when  brought  in  association  with  the  microorganism  in  question.  Im- 
munity in  this  sense  is  an  example  of  allergic  and  is  discussed  more  in 
detail  under  anaphylaxis. 


HEMOLYSIS 

Hemolysins  are  substances  that  lake  the  blood ;  that  is,  they  dis- 
solve the  hemoglobin  from  the  red  blood  corpuscle  and  set  it  free  in 
solution.  A  certain  part  of  the  stroma  of  the  red  corpuscle  is  also  de- 
stroyed in  complete  hemolysis.  Some  of  the  hemolysins  are  specific  and 
others  are  not.  Thus,  distilled  water  will  dissolve  the  hemoglobin  from 
the  red  corpuscles  of  almost  all  animals.  Other  known  non-specific 
hemolytic  substances  are  various  alkalis  and  acids;  plant  poisons,  such 
as  recin  and  abrin ;  bacterial  poisons,  such  as  tetanolysin  and  staphyloly- 
sin ;  and  animal  poisons,  such  as  snake  venom,  scorpion  venom,  etc.  The 
specific  hemolysins  are  obtained  by  treating  (i.  e.,  immunizing)  one 
animal  species  with  the  blood  corpuscles  of  another.     For  example,  the 


444  IMMUNITY 

blood  corpuscles  of  a  guinea-pig  are  injected  into  a  rabbit.  After  several 
such  injections  the  blood  serum  of  the  rabbit  will  contain  hemolytic 
substances  for  the  guinea-pig's  corpuscles.  The  corpuscles  used  for  im- 
munization are  obtained  by  drawing  the  blood  of  the  animal  into  isotonic 
salt  solution  (0.85  per  cent.)  containing  about  1  per  cent,  of  sodium 
citrate,  which  prevents  coagulation.  The  eitrated  blood  is  then  centrif- 
ugalized,  the  supernatant  fluid  drawn  off  and  replaced  with  isotonic  salt 
solution.  This  process  is  repeated  three  or  four  times  and  is  known  as 
washing  the  corpuscles.  The  object  is  to  remove  all  trace  of  serum  con- 
taining complement  and  other  substances.  If  this  is  not  done  the  results 
will  be  unnecessarily  complicated  and  misleading.  The  washed  corpuscles 
are  injected  into  the  peritoneal  cavity  aljout  once  a  week  or  ten  days  until 
the  blood  contains  the  desired  hemolytic  action.  When  this  point  is 
reached  can  only  be  determined  by  withdrawing  small  quantities  of  the 
blood  and  testing  it. 

Hemolytic  tests  are  made  by  adding  together  the  complement  and 
the  immune  bodies.  The  corpuscles  are  obtained  as  above  described, 
washed  three  or  four  times,  and  suspended  in  isotonic  salt  solution,  so 
that  they  are  present  in  the  proportion  of  about  5  to  10  per  cent,  by 
volume  of  the  salt  solution.  One  c.  c.  of  this  suspension  is  placed  in  a 
small  test  tube.  To  this  is  then  added  the  immune  body  contained  in 
the  serum  of  the  animal  that  had  been  injected  with  the  corpuscles. 
This  immune  serum  is  first  heated  to  55°  or  56°  C.  for  one  hour  in 
order  to  destroy  the  complement.  This  degree  of  heat  does  not  injure 
the  immune  body.  Uniform  amounts  of  the  complement  are  obtained 
by  adding  a  definite  quantity  (0.2  of  a  c.  c.)  of  fresh  serum  to  each  test 
tube.  Each  test  tube  then  contains  a  uniform  quantity  of  the  corpuscles 
to  be  tested,  a  uniform  quantity  of  complement  in  the  fresh  serum,  and 
a  variable  quantity  of  heated  immune  serum  containing  the  immune 
body.  In  most  cases  normal  saline  solution  is  added  to  bring  the  whole 
up  to  a  definite  volume — say  5  c.  c. 

These  mixtures  are  now  incubated  at  37°  C.  for  two  hours,  being 
stirred  or  shaken  once  or  twice  in  the  meantime.  The  test  tubes  are 
now  removed  and  placed  in  a  vertical  position  in  the  ice  chest  from 
12  to  24  hours  and  then  examined.  If  no  hemolysis  has  taken  place 
the  supernatant  fluid  will  be  untinged  and  the  corpuscles  will  have 
settled  in  a  distinct  layer  at  the  bottom.  If  there  is  complete  hemol- 
ysis the  fluid  will  be  deeply  and  uniformly  colored  and  there  will  be 
no  sediment  or  only  a  minute  deposit  of  stromata.  If  the  reaction  is 
partial,  the  fluid  will  be  less  deeply  colored  and  there  will  be  more  or 
less  of  a  deposit  of  undissolved  corpuscles.  It  must  be  remembered 
that  many  bacteria  produce  hemolysis  and  that,  if  the  mixtures  of  cor- 
puscles and  sera  be  incubated  for  long  periods,  fallacies  may  arise  from 
such  contaminations. 


THE    BOilDET-GEXGOU    PHENOMENON  445 


CYTOTOXINS 

If  instead  of  red  blood  cells  an  animal  is  treated  with  the  body 
cells  or  glandular  cells  of  another  species,  it  develops  the  power  to 
dissolve  the  cells  in  question.  This  power  is  contained  in  the  blood 
serum  and  is  brought  about  by  substances  known  as  cytotoxins,  which 
are  entirely  similar  to  the  bacteriolysins,  the  hemoWsins,  and  other  lytic 
substances.  Cytotoxins  have  been  obtained  Avith  the  spleen  (leukocidin), 
with  the  sperm  (spermotoxin),  liver  cells  (hepatotoxin),  kidney  cells 
(nephrotoxin),  gastric  mucosa  (gastrotoxin),  placental  tissue  (syncy- 
tiolysin  or  placentolysin),  prostatic  tissue  (prostatolysin),  brain  (neuro- 
toxin), and  other  organs  and  tissues.  When  the  cytotoxins  were  discov- 
ered they  aroused  great  enthusiasm  in  the  hope  that  it  would  now  be 
possible  to  dissolve  and  destroy  such  foreign  cells  as  cancer  and  other 
tumors,  and  pathological  processes  in  which  it  is  desirable  to  get  rid 
of  certain  cellular  elements.  The  practical  results  have  been  exceedingly 
disappointing,  as  further  investigations  have  shown  that  these  cytotoxins 
are  exceedingly  weak  and,  further,  are  not  very  specific. 


THE    BORDET-GENGOU     PHENOMENON— FIXATION    OF 
COMPLEMENT 

Bordet  and  Gengou  ^  found  that  bacteria  and  also  red  blood  cells 
could  be  "sensitized"  by  placing  them  in  heated  immune  serum.  The 
immune  serum  is  heated  to  55°  or  56°  C.  in  order  to  destroy  the  com- 
plement, leaving  only  the  thermostable  "substance  sensibilitrice"  which 
unites  with  the  bacteria  or  the  red  blood  cells,  and  thus  prepares  or 
sensitizes  them  to  the  action  of  the  complement.  If,  now,  these  sen- 
sitized bacteria  or  red  corpuscles  are  added  to  fresh  serum,  all  the  com- 
plement contained  in  the  fresh  serum  is  removed  or  fixed  so  that  the 
fluid  will  no  longer  dissolve  bacteria  or  cells.  These  facts  are  of  very 
great  importance,  and  upon  them  are  based  the  Wassermann  reaction  for 
syphilis  and  other  practical  applications  in  immunology.  The  comple- 
ment fixation  test  is  also  used  in  the  diagnosis  of  gonococcus  infection, 
glanders  (p.  313),  streptococcus  infections,  pertussis,  meningitis,  typhoid 
fever,  and  other  infections. 

The  reaction  of  fixation  based  upon  the  work  of  Bordet  and  Gengou 
has  many  useful  practical  applications  in  addition  to  the  Wassermann 
reaction  for  the  diagnosis  of  syphilis.    If  either  the  antigen  or  the  anti- 

^  Bordet:  Ann.  de  I'lnst.  Pasteur,  Vol.  XIV,  1900,  p.  257;  Vol.  XV,  1901,  p. 
289. 

Gengou:      Ann.  de  VInst.  Pasteur,  Vol.  XVI,   1902,  p.   734. 
Bordet  and  Gengou:     Compte  rendu  Acad.,  Vol.  CXXXVII,  p.  351. 


446  IMMUNITY 

body  are  unknown,  their  presence  may  be  determined  through  the  reaction 
of  fixation,  because  it  is  strictly  specific.  The  problem  is  something  like 
the  theorem  in  geometry  with  the  triangle;  two  sides  and  an  angle  of  a 
triangle  being  known,  the  other  side  and  angles  may  be  determined. 

The  antigen  is  any  substance  which,  when  injected  into  a  suitable 
animal,  has  the  power  of  generating  an  antibody.  Practically  all  patho- 
genic bacteria  and  pathogenic  protozoa  act  as  antigens ;  many  albuminous 
bodies,  such  as  the  venoms,  the  enzymes,  and  bland  proteins,  may  also 
act  as  antigens.  As  the  reaction  is  specific,  it  is  possible  to  determine 
whether  a  particular  microorganism  is  the  true  cause  of  a  disease  or  not. 
Thus,  Bordet  was  enabled  to  satisfy  himself  that  the  bacillus  which  he 
isolated  during  the  early  stages  of  whooping-cough  was  the  true  cause 
of  that  disease,  as  it  gave  the  reaction  of  fixation  with  a  specific  antibody. 
On  the  other  hand,  if  the  antigen  is  known,  the  diagnosis  may  be  made 
through  the  reaction  of  fixation,  as  in  the  case  of  syphilis  and  the  Wasser- 
mann  reaction. 

The  Wassermann  reaction  for  syphilis  is  a  special  method  of  applica- 
tion of  the  Bordet-Gengou  phenomenon. 

The  following  is  a  brief  description  of  the  Wassermann  reaction  as 
carried  out  for  the  Massachusetts  State  Department  of  Health,  by  Dr.  W. 
A.  Hinton,  under  my  direction. 

Two  antigens  are  used:  one  is  an  alcoholic  extract  of  a  liver  from 
a  case  of  hereditary  syphilis,  containing  the  Treponema  pallidum;  the 
other  is  an  alcoholic  extract  of  a  human  heart  which  is  then  saturated 
with  cholesterin  at  room  temperature.  Each  of  these  antigens  is  diluted 
with  0.85  per  cent,  salt  solution  before  testing,  in  the  proportion  of  4 
parts  of  the  antic^en  extract  to  16  parts  of  0.85  per  cent,  salt  solution. 
The  amount  to  be  used — the  dosage — is  carefully  determined  by  testing 
each  antigen  against  a  large  number  of  known  positive  and  known 
negative  specimens  of  blood.  Any  antigen  which  gives  a  positive  reaction 
on  a  known  negative  specimen  of  blood  ("false  positive"')  is  unsuitable 
for  testing  and  should  be  rejected.  Further  it  is  unsafe  to  employ  an 
antigen  when  twice  its  dosage  inhibits  hemolysis  when  incubated  for  1 
hour  with  "the  hemolytic  system"  consisting  of  complement,  and  the 
hemolytic  mixture.  ( See  Antigen  Control  in  table  on  Wassermann  Test. ) 
Usually  0.1  c.  c.  to  0.2  c.  c.  of  the  diluted  antigen  is  used.  Lecithin  and 
other  lipoidal  substances  may  also  act  as  antigen.^ 

Syphilitic  antibody  in  the  patient's  serum  to  be  tested  is  the  unknown 
quantity.    This  serum  is  heated  in  a  water  bath  to  55°  C.  for  30  minutes 

*In  routine  examinations  upon  a  large  number  of  specimens  it  is  better  to 
test  all  specimens  first  with  a  cholesterinized  alcoholic  extract  of  a  human 
heart,  this  antigen  being  more  sensitive  to  syphilic  antibody,  and  then  re-test 
the  positives  with  the  same  antigen  and  also  with  the  alcoholic  extract  of  a 
syphilitic  liver  in  order  to  be  perfectly  certain  of  both  the  specificity  and  tech- 
nic  of  the  test. 


THE    BOKDET-GENGOU    PHENOMENON 


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448  IMMUNITY 

to  destroy  its  complement.  One-tenth  cubic  centimeter  of  the  patient's 
serum  is  used  in  the  test  and  twice  this  quantity  is  used  for  the  control  in 
order  to  show  that  the  serum  does  not  possess  inhibitory  substances  other 
than  specific  antibodies. 

The  complement  is  obtained  from  the  serum  of  guinea-pigs'  blood 
which  has  been  kept  on  ice  from  12  to  14  hours.  Ten  per  cent,  of  guinea- 
pigs'  serum  in  0.85  per  cent,  salt  solution  is  prepared.  The  amount 
used  in  testing  is  twice  the  minimum  quantity  necessary  to  hemolyze 
the  hemolytic  mixture.  Usually  this  amounts  to  0.4  c.  c.  to  0.5  c.  c.  of 
the  10  per  cent,  dilution. 

The  antigen^  the  patient's  serum  and  the  complement  are  mixed  in  a 
tube  and  then  incubated  in  a  water  bath  at  37°  C.  for  40  minutes,  at  the 
end  of  which  time  all  the  complement  in  the  mixture  has  been  "fixed," 
if  syphilitic  antibody  is  present  in  the  patient's  serum  that  has  been  used. 

The  hemolytic  mixture  consists  of  equal  parts  of  a  5  per  cent,  suspeii- 
sion  of  washed  sheep's  corpuscles  and  heated  immune  rabbit's  serum. 
This  mixture  is  incubated  in  a  water  bath  at  37°  C.  for  I/2  hour  to  sensi- 
tize the  cells  (washed  sheep's  corpuscles).  One  cubic  centimeter  of  this 
hemolytic  mixture  is  now  added  to  the  mixture  of  antigen,  complement 
and  patient's  serum  previously  prepared  and  incubated  at  37°  C.  for  60 
minutes. 

The  5  per  cent,  suspension  of  sheep's  corpuscles  in  0.85  per  cent,  salt 
solution  is  prepared  from  defibrinated  sheep's  blood.  The  corpuscles  are 
washed  three  times  and  for  each  washing  4  to  5  times  as  much  0.85  per 
cent,  salt  solution  is  used  as  the  original  volume  of  the  defibrinated  blood 
employed.  Finally  withdraw  the  supernatant  salt  solution  until  the 
volume  of  cells  and  salt  solution  together  is  equal  to  the  volume  of 
defibrinated  blood  originally  used.  This  suspension  of  comuscles  in  sa^"" 
solution  is  called  washed  sheep's  corpuscles. 

The  heated  immune  rabbit's  serum  is  prepared  by  injecting  washed 
sheep's  corpuscles  into  the  peritoneal  cavity  of  a  rabbit  at  three-day 
intervals,  namely,  first  injection  7  c.  c. ;  second,  14  c.  c. ;  third,  21  c.  c, 
and  finally  28  c.  c.  The  rabbit  is  bled  on  the  9th  or  10th  day  after  the 
last  injection  and  the  clear  serum  is  heated  in  a  water  bath  to  55°  C. 
for  y2  hour.  This  treated  rabbit's  serum  contains  amboceptor  and  is 
diluted  with  0.85  per  cent,  salt  solution  so  that  0.25  c.  c.  of  this  dilution 
will  hemolyze  0.5  c.  c.  of  a  5  per  cent,  suspension  of  heated  sheep's  cor- 
puscles. This  procedure  is  called  standardization  of  the  amboceptor. 
In  the  test  twice  the  quantity,  or  0.5  c.  c.  of  amboceptor  is  used.  Small 
quantities  of  the  rabbit's  serum  is  diluted  from  time  to  time  as  needed. 
After  the  entire  system  containing  the  antigen,  patient's  serum,  the 
complement  and  the  hemolytic  mixture  is  well  mixed  by  shaking  and  in- 
cubating at  37°  C.  in  water  bath  for  one  hour,  the  result  is  read  and 
again  after  having  been  kept  in  an  icebox  for  about  12  hours. 


THE    NEISSEE-WECHSBEEG    PHENOMENON" 


449 


The  absence  of  hemolysis  indicates  the  presence  of  syphilitic  anti- 
body in  the  patient's  serum,  and  therefore  a  positive  reaction.  The 
presence  of  hemolysis  indicates  the  absence  of  syphilitic  antibody  in  the 
patient's  serum,  and  therefore  a  negative  reaction.  Partial  hemolysis 
signifies  a  doubtful  reaction.  It  is  advisable  to  test  several  specimens 
from  such  a  case,  and  to  interpret  a  persistently  or  predominatingly 
doubtful  reaction  as  indicative  of  a  syphilitic  infection. 


THE  NEISSER-WECHSBERG  PHENOMENON  OR  DEVIATION 
OF   THE   COMPLEMENT 

Neisser  and  Wechsberg  in  1901  ^  found  that,  although  the  addition 
of  a  small  amount  of  immune  serum  renders  normal  serum  more  bac- 
tericidal or  increases  its  power  of  protection,   a  greater  addition  robs 


Diagram    Illustrating  Deviation  of  Complemelnt 

(Neisser  Wechsberg  Phenomenon) 

Test 

A 
BACTERIA 

Same  number 
in  each  Test. 

B 

Complement 

Same  amount 
in  each  Test 

c 

Amboceptor 

Variable  atnount  of  bnrnune 
Serium  in  each  Test 

Combine 

A  Band  C 

Result 

I 

Ill     1 

\7\y\ytr\y 

P 

g\y\7\y\y 

Few  or  no 
baderia  killed. 

I 

mil 

\7\7\7\y\7 

C3  CO  CO  CO  CO 

ff?ff 

AH  bacteria 
killed. 

IE 

III! 

\7\y\7\7\I/ 

CO  CO  CO  CO  CO 
CO  CO  CO  CO  CO 

Few  or  no 
bacteria  killed 
because  the 
pjmplcment  is 
deviated  by  the 
excess  of 
Amboceptor. 

Fig.  59. 
Munch,  med.  Woohenschr.,   1901,  No.   18. 
16 


450  IMMUIsTTTY 

it  of  most,  and  sometimes  of  all,  of  its  bactericidal  power.  In  other 
words,  the  solvent  effect  of  the  immune  body  on  cells  or  bacteria  in 
the  presence  of  complement  diminishes  as  an  excess  of  the  immune 
body  is  added.  This  particular  action  is  explained  by  Neisser  and 
Wechsberg  as  due  to  a  locking  up  or  deviation  (ahlenlcung)  of  the  com- 
plement which  is  brought  about  by  an  excess  of  the  immune  body.  The 
phenomenon  is  better  understood  from  a  study  of  an  example  given  by 
Neisser : 

(1)  Bacteria+1  unit  immune  serum-t-complement=little  or  no 
destruction  of  the  bacteria. 

(2)  Bacteria+5  units  immune  serum-|-complement^complete  de- 
struction of  the  bacteria. 

(3)  Bacteria-f-lO  units  immune  serum-|-complement=no  destruc- 
tion of  the  bacteria. 

In  the  above  experiment  it  is  necessary  that  the  number  of  bacteria 
and  the  amount  of  complement  shall  remain  practically  the  same  in  all 
three  tests.    The  immune  serum  is  the  only  factor  that  should  vary. 

In  (1),  few  or  no  bacteria  are  killed  because  there  are  not  enough 
immune  bodies  (amboceptors)  to  unite  the  complement  to  the  bacteria. 

In  (3),  the  proper  proportion  of  amboceptors  and  complement  occurs 
so  that  all  the  bacteria  are  killed. 

In  (3),  few  or  no  bacteria  are  killed  for  the  reason  that  the  comple- 
ment is  deviated  by  the  excess  of  amboceptors.  ■ 

The  action,  therefore,  while  specific,  is  strictly  quantitative,  depend- 
ing upon  the  amount  of  amboceptors  present.  This  explains  why  ah 
immune  serum  may  be  effective  in  certain  infections  if  the  proper  dose 
is  used,  but  why  large  amounts  of  immune  serum  may  be  ineffective  in 
controlling  the  course  of  the  disease. 

Isohemolysins  have  the  property  of  destroying  the  red  blood  cells  of 
the  same  species.  They  occur  naturally  in  certain  animals,  principally  in 
the  horse  and  in  man.  They  may  also  be  produced  experimentally  in 
certain  animals,  as  in  goats,  by  the  injection  of  the  blood  of  other  goats. 
There  is  further  the  possibility  that  autohemolysins  may_  be  produced 
which  destroy  the  blood  cells  of  the  individual  himself.  These  have  not 
been  produced  artificially,  but  are  said  to  occur  in  paroyxsms  of  hemo- 
globinuria. The  subject  of  isohemolysins  is  of  importance  in  transfu- 
sion. 

PRECIPITINS 

Another  class  of  immune  bodies  known  as  the  precipitins  may  readily 
be  produced  in  the  blood  serum  of  animals  by  the  injection  of  bacteria 
or  albuminous  substances.  The  precipitating  action  of  immune  sera  was 
discovered  bv  R-  Kraus  in  1S97.    "When  the  clear  antiserum  is  added  to 


PEECIPITINS  451 

the  clear  antigen  in  solution,  the  mixture  of  the  two  fluids  becomes 
opalescent,  then  opaque  from  the  formation  of  a  precipitate,  and  after 
a  time  this  settles  to  the  bottom  of  the  test  tube,  leaving  a  clear  super- 
natant fluid.  The  precipitate  consists  of  an  insoluble  combination  of 
two  substances,  one  of  which  is  present  in  the  antiserum,  the  other  in  the 
antigen.  This  insoluble  precipitate  is  known  as  the  precipitum.  The 
substance  in  the  antigen  is  known  as  the  precijDitable  substance  or  pre- 
cipitinogen, and  the  substance  in  the  antiserum  is  called  the  precipitin. 
Precipitums  are  doubtless  formed  both  within  and  without  the  body  when 
proper  conditions  of  antibody  and  antigen  are  present,  without,  however, 
always  causing  a  visible  precipitum. 

The  precipitins  are  quite  analogous  to  the  agglutinins,  and  from  the 
standpoint  of  |)hysical  chemistry  are  often  classified  with  them.  It  is  now 
known  that  proteins  do  not  form  true  solutions,  but  molecular  or  colloidal 
suspensions.  The  effect  of  the  addition  of  a  precipitin  is  to  cause  the 
agglutination  of  these  molecules  in  a  manner  entirely  analogous  to  the 
agglutination  of  bacilli.  According  to  Emery,  the  laws  which  govern 
the  action  of  the  precipitins  and  agglutinins  are  entirely  similar,  and 
theoretically  it  would  probably  be  more  accurate  to  consider  them  imder 
one  head.  The  practical  applications  of  the  two  classes  of  antibodies 
are,  however,  very  different,  and  it  is  more  convenient  to  treat  them 
as  separate  substances. 

The  bacterial  precipitins  were  those  first  discovered.  Kraus  added 
seme  typhoid  serum  to  a  filtered  culture  of  typhoid  bacilli  and  obtained 
a  precipitate  when  the  two  clear  solutions  were  brought  together.  The 
same  happens  with  cultures  of  cholera,  plague,  and  other  bacteria.  Cer- 
tain bacteria,  however,  do  not  produce  a  precipitable  substance.  This  is 
notably  the  case  with  diphtheria.  Thus,  when  dij^htheria  antitoxin  is 
added  to  diphtheria  toxin,  no  visible  reaction  takes  place.  In  this  case 
the  diphtheria  antitoxin  should  contain  the  antibody  or  precipitinogen. 
The  filtered  broth  culture  is  the  antigen  and  should  contain  the  pre- 
cipitin; however,  one  or  both  of  these  substances  must  be  absent,  as  a 
precipitum  is  not  formed  when  they  are  brought  together. 

Tsistowitch  in  ■  1899  found  that  precipitins  may  be  produced  by 
injecting  albuminous  substances  into  suitable  animals.  Thus,  if  rabbits 
are  injected  with  horse  serum  or  with  eel's  blood,  the  blood  serum  of 
the  treated  rabbit  will  precipitate  the  blood  serum  of  the  horse  or  the 
eel's  blood  respectively.  This  reaction  is  used  in  forensic  medicine  for 
the  recognition  of  blood  stains,  which  will  presently  be  discussed.  The 
chemical  nature  of  the  precipitins  is  not  known.  They  come  down  with 
the  globulins.  In  the  terms  of  the  side-chain  theory  they  contain  two 
groups,  one  a  thermostable  haptophore  or  combining  group,  the  other  a 
thermolabile  functioning  group.  Precipitins  are  destroyed  by  heat,  light, 
moisture;  and  other  external  influences  about  as  readily  as  the  agglu- 


463  IMMUNITY 

tinins.  Precipitating  sera  should,  therefore,  be  kept  in  a  dry  state,  in  a 
cool  place,  and  preserved  from  light.  A  propreeipitoid  zone  entirely 
analogous  to  the  proagglutinoid  zone  is  observed  under  certain  conditions. 
Precipitins  like  agglutinins  act  more  quickly  at  the  body  temperature 
and  require  the  presence  of  certain  salts  for  their  action.  According  to 
Friedemann,  the  amount  of  precipitum  formed  depends  on  the  quantity 
of  the  salts  present. 

The  relation  of  precipitins  to  immunity  is  not  entirely  clear.  There 
is  a  strong  suspicion  that,  like  all  antibodies,  they  play  some  part  in 
the  mechanism  of  immunity  in  certain  infections,  but  Just  what  part 
is  obscure.  It  is  quite  evident  that  the  presence  of  precipitins  in  the  blood 
must  have  valuable  protective  properties  against  the  poisons  of  certain 
infections.  The  immunity  in  this  case  would  be  due  to  the  throwing  out 
of  solution  of  the  poison,  thus  rendering  it  insoluble  and  inert. 

Nuttal  in  his  "Blood  Relationship''  made  a  very  careful  study  of  the 
question  of  specificity  of  the  precipitins. 

He  showed  that  the  reaction  of  the  precipitins,  like  the  reaction  of 
other  similar  antibodies,  is  relatively  specific  or  quantitatively  specific. 
If  the  antiserum  is  powerful  enough  it  will  react  with  all  the  bloods 
of  animals  in  the  same  great  division  of  the  animal  kingdom.  Thus, 
a  strong  antihuman  serum,  that  is,  a  serum  obtained  by  injecting  human 
blood  into  rabbits,  will  give  a  precipitate  when  this  rabbit  serum  and 
human  serum  are  brought  together ;  it  will  also  react  with  apes,  monkeys, 
etc.,  but  not  in  such  high  dilutions,  and  a  slight  trace  of  precipitum 
appears  after  a  long  period  even  when  mixed  with  the  serum  of  more 
remote  mammalia,  but  no  precipitate  occurs  with  the  blood  of  birds, 
fishes,  etc.  A  quite  similar  relationship  holds  with  lactosera  and  with  the 
precipitating  sera  for  muscle  proteids;  the  antisera  for  egg  proteids  are 
apparently  less  specific.  Precipitins,  then,  are  not  specific  as  regards  the 
animal  species  from  which  they  are  derived,  but  possess  that  partial 
specificity  seen  in  the  cytotoxins  and  in  the  group  reaction  of  the  agglu- 
tinins. According  to  Emery,  they  are  specific  as  regards  the  antibodies 
which  bring  them  into  existence,  irrespective  of  the  source  from  which 
the  antigen  is  derived.  For  medico-legal  purposes  the  specificity  of  the 
reaction  may  be  considered  satisfactory,  provided  the  tests  are  made  quan- 
titatively, in  which  case  the  reaction  is  both  specific  and  delicate.  In  fact, 
the  delicacy  of  the  reaction  is  truly  astonishing.  Thus,  Ascoli  obtained  an 
anti-egg  albumin  serum  which  gave  a  precipitate  with  1-1,000,000  dilu- 
tion of  egg  albumin ;  and  Stern  an  antihuman  serum  which  reacted  with 
serum  at  a  dilution  of  1-50,000.  While  these  are  extreme  figures,  it  is 
not  unusual  to  obtain  precipitates  in  dilutions  of  1-5,000. 

Tests  for  Blood. — In  carrying  out  the  precipitin  tests  for  the  recog- 
nition of  blood  stains,  as  suggested  by  Uhlenhuth  and  Wassermann,  it  is 
necessary  first  to  obtain  an  antiserum.    This  is  usually  gained  from  rab- 


PRECIPITIN'S        ^  453 

bits,  which  are  injected  intravenously  or  intraperitoneally  at  intervals  of 
three  or  four  days  with  human  serum.  The  human  serum  may  readily 
be  obtained  by  puncturing  a  vein  at  the  bend  of  the  elbow,  or  from  the 
placenta,  or  from  a  cadaver;  pleuritic  or  ascitic  fluid  may  also  be  used. 
The  amount  injected  rises  from  1  to  3  or  4  c.  c.  in  the  case  of  intravenous 
injections,  or  twice  as  much  or  even  more  into  the  peritoneum.  The 
course  of  treatment  lasts  three  or  four  months.  A  simpler  method  is  to 
give  larger  doses  up  to  10  c.  c.  or  more  intraperitoneally  at  intervals  of  a 
week.  The  intervals  should  not  be  longer  than  this,  for  danger  of 
complicating  anaphylactic  reactions.  The  blood  may  be  drawn  from  a 
vein  or  the  heart  of  the  rabbit  from  time  to  time  as  needed,  or  the  ani- 
mal may  be  chloroformed  and  exsanguinated  through  the  carotid  artery, 
or  as  much  blood  as  possible  may  be  collected  from  the  heart. 

The  blood  to  be  tested  is  usually  in  th&  form  of  clots  or  stains 
upon  linen,  pistols,  and  other  surfaces.  These  stains  are  macerated 
with  normal  saline  solution  or  with  1  per  cent,  sodium  hydrate.  In 
the  case  of  very  old  stains  Zienka  recommends  the  use  of  a  strong 
solution  of  potassium  eyanid  which  is  subsequently  neutralized  with 
tartaric  acid.  The  fluid  is  then  examined  with  the  microscope  and 
tested  spectroscopically  to  determine  the  presence  of  blood  corpuscles 
and  pigments,  so  as  to  be  sure  we  are  really  dealing  with  blood.  The 
solution  is  then  filtered.  In  order  to  determine  the  approximate  strength 
of  the  solution  it  is  sufficient  to  bubble  air  through  the  fluid.  A  dilu- 
tion of  blood  serum  in  the  proportion  of  1-1,000  will  produce  a  stable 
foam.  If  a  stable  foam  is  not  produced  it  indicates  that  the  protein 
material  has  not  actually  passed  into  solution  or  is  too  dilute  to  be 
of  service  in  the  test.  Three  tests  are  made.  In  the  first  tube  one 
part  of  the  fiuid  under  examination  is  mixed  with  two  parts  of  the 
antiserum,  the  second  contains  the  fluid  alone,  and  the  third  antiserum 
plus  normal  saline  solution.  Further  controls  in  which  the  antiserum 
is  mixed  with  diluted  serum  from  animals  other  than  man  may  also 
be  made.  The  tubes  are  then  incubated  at  37°  C.  and  examined  from 
time  to  time.  A  positive  result  is  obtained  if  there  is  a  precipitate  in 
the  first  tube  and  not  in  the  others.  In  case  a  precipitate  is  obtained 
further  tests  are  then  made  with  greater  dilutions.  With  a  powerful 
antiserum  a  reaction  may  usually  be  obtained  in  dilutions  so  high  that 
evidence  of  the  presence  of  proteids  is  barely  obtainable  by  ordinary 
chemical  means.  The  weak  point  in  the  method  is  that  it  is  never  possi- 
ble to  say  exactly  how  much  of  the  protein  matter  of  the  clot  has  been 
dissolved,  and  thus  it  is  not  possible  to  obtain  precise  quantitative  results. 
With  an  unknown  blood  serum,  unaltered,  and  in  the  fluid  state  the 
test  can  be  carried  out  with  almost  complete  certainty,  but  this  is  rarely 
if  ever  possible  in  medico-legal  cases. 

Another  test  for  blood  has  been  introduced  by  Neisser  and  Sachs  and 


454  IMMUJTITY 

based  on  the  Gengou  reaction  of  fixation  of  the  complement.  The 
test  is  extraordinarily  sensitive.  Neisser  and  Sachs  found  that  one- 
millionth  part  of  a  cubic  centimeter  of  human  serum  is  readily  demon- 
strable. The  technic  is  complicated,  and,  according  to  Emery,  it 
appears,  moreover,  that  complement  may  be  extracted  in  an  altogether 
non-specific  manner  by  substances  other  than  the  combination  of  anti- 
gen and  antibody.  Another  serious  objection  is  that  a  similar  deviation 
of  the  complement  may  be  brought  about  by  means  of  sweat,  so  that 
if  the  reaction  were  obtained  in  a  stain  on  body  linen  it  would  be  of 
doubtful  significance. 

The  precipitin  reaction  further  finds  practical  application  in  deter- 
mining the  nature  of  meat,  whether  fresh,  as  in  the  case  of  beef  sus- 
pected to  be  horse  flesh,  or  prepared,  as  in  sausages,  etc.  For  these 
tests  the  antiserum  is  prepared  by  injecting  rabbits  with  meat  juices 
or  an  unheated  watery  extract  of  the  meat,  and  the  test  is  carried 
out  on  lines  similar  to  those  described  above. 


AGGLUTININS 

Agglutinins  were  definitely  described  in  1896  by  Gruber  and  Dur- 
ham, and  a  few  days  later  by  PfeifEer  and  KoUe.  Shortly  thereafter 
Widal  announced  the  fact  that  the  blood  serum  of  a  typhoid  patient 
will  agglutinate  the  typhoid  bacillus  in  high  dilutions.  The  phenom- 
enon of  agglutination  with  special  reference  to  typhoid  fever  is,  there- 
fore, often  called  the  Widal  reaction  or  the  Gruber  reaction.^ 

Agglutination  consists  in  a  clumping  or  grouping  of  the  bacteria 
into  clusters,  just  as  though  they  were  iron  filings  drawn  about  a  mag- 
netic point.  Usually  they  are  immobilized  before  they  are  draAvn  to- 
gether into  a  clump  or  cluster.  Theobald  Smith  has  shown  that  the 
first  phenomenon,  the  immobilization  of  bacteria,  may  be  due  to  a 
flagellar  agglutinin,  and  that  the  second  phenomenon,  the  clumping, 
may  be  due  to  a  cellular  agglutinin. 

The  agglutination  of  bacteria  apparently  does  little  harm  to  them 
other  than  rendering  them  motionless,  for  they  are  not  altered  in  ap- 
pearance, viability,  or  virulence.  Bacteria  that  have  been  agglutinated 
may  again  multiply  and  grow  vigorously.  Agglutination  is  an  im- 
portant source  of  error  in  counting  the  number  of  bacteria  in  any  fluid. 
A  cluster  will  develop  into  one  colony  and  thereby  give  misleading  re- 
sults.    The  apparent  diminution  in  the  number  of  bacteria  in  freshly 

^  The  phenomenon  of  agglutination  had  been  previously  observed  by  Charrin 
and  Roger  in  1899  in  the  case  of  the  Bacillus  pyocyaneus.  It  was  also  observed 
by  Metchnikoff  in  the  case  of  the  Vibrio  metchnikovi  in  1891.  Similar  appear- 
ance had  also  been  seen  by  Issaeff  in  1893. 


AGGLUTININS  ^55 

drawn  milk,  judged  by  the  mimber  of  colonies  that  develop  upon  agar 
plates  and  known  as  the  germicidal  property  of  milk,  is  largely  a  phe- 
nomenon of  agglutination. 

Agglutination  may  occur  quickly  or  slowly,  depending  upon  the 
temperature,  the  dilution  of  the  serum  or  fluid  containing  the  agglu- 
tinin, and  upon  other  factors;  hence,  it  is  important  in  reporting  posi- 
tive or  negative  tests  in  the  diagnosis  of  typhoid  fever,  malta  fever, 
and  other  infections  always  to  state  the  dilution,  the  time,  the  tem- 
perature, and  other  conditions  under  which  the  test  was  made.  The 
interpretation  of  the  results  may  depend  upon  these  factors. 

Agglutination  may  readily  be  seen  by  the  naked  eye.  A  uniform 
suspension  of  bacteria  in  a  test  tube  under  the  action  of  an  agglutinin 
first  becomes  granular;  the  granules  increase  in  size  and  flock  into 
masses  with  intervening  clear  spaces.  Then  these  flocculi  settle  to  the 
bottom  as  a  precipitate,  leaving  the  supernatant  fluid  clear.  Under  the 
microscope  the  bacteria  are  first  seen  to  lose  their  motion,  then  to  be 
drawn  together  into  irregular  clumps  or  clusters,  which  increase  in 
size.  The  macroscopic  method  is  much  more  dependable  in  testing  ag- 
glutinins than  the  microscopic  method.  The  latter  is  subject  to  several 
sources  of  error,  and  the  end  point  is  not  as  sharply  defined  as  in  the 
macroscopic  method. 

Agglutination,  like  almost  all  chemical  processes,  takes  place  more 
quickly  when  warm  than  in  the  cold.  The  reaction  is  best  at  37°  C. 
The  clumping  usually  takes  place  more  slowly  with  the  non-motile  bac- 
teria. Certain  strains  of  some  species  of  bacteria  agglutinate  more 
readily  than  others.  Thus,  the  typhoid  bacillus  is  usually  agglutinated 
readily  with  its  specific  serum,  but  some  strains  are  agglutinated  with 
considerable  difficulty;  in  general,  when  first  isolated,  they  resist  agglu- 
tination. This  resistance  or  "immunity"  of  the  microorganism  usually 
wears  off  after  a  number  of  subcultures.  A  very  interesting  phenomenon 
in  agglutination  which  has  considerable  practical  importance  is  the  so- 
called  proagglutinoid  zone;  that  is,  bacteria  sometimes  will  not  agglu- 
tinate in  a  stronger  dilution,  whereas  they  agglutinate  readily  in  a  weaker. 
The  proagglutinoid  zone  is  occasionally  found  with  the  typhoid  bacillus, 
but  especially  with  the  Micrococcus  melitensis.  Thus,  this  coccus  may 
give  no  reaction  in  a  dilution  between  1-10  and  1-100,  whereas  it  will 
clump  strongly  at  1-200  and  higher. 

Agglutinins  are  not  very  resistant  to  light,  putrefactive  processes, 
and  dryness.  They  are  not  much  harmed  at  a  temperature  of  55°  to 
56°  C,  but  are  destroyed  at  65°  to  70°  C.  They  are  very  sensitive  to 
acids;  they  are  partially  held  back  by  a  Pasteur-Chamberland  filter; 
they  are  not  dialyzable.  They  may  be  preserved  for  a  very  long  time 
in  dried  serum  protected  from  light  and  moisture. 

The  chemical  composition  of  the  agglutinins  is  not  known.     Like 


456  IMMUNITY 

antitoxin  and  other  antibodies,  they  come  down  with  the  globulins  when 
precipitated  with  ammonium  sulphate.  They  unite  directly  with  the 
bacteria  or  other  cells  and,  according  to  Ehrlich,  contain  both  a  hap- 
tophore  and  an  "agglutinophore"  group. 

Agglutinins  may  readily  be  produced  by  injecting  either  live  or 
dead  bacterial  cells  into  a  suitable  animal.  The  injections  may  be  given 
either  subcutaneously,  intravenously,  intraperitoneally  or  the  micro- 
organisms may  be  rubbed  upon  the  closely  shaven  skin.  Agglutinins 
may  even  be  produced  by  giving  the  microorganisms  by  the  mouth. 
Agglutinins  in  highest  concentration  may  be  obtained  by  repeated  in- 
jections, every  10  or  12  days,  continued  over  a  long  period  of  time. 
In  experimental  work  in  the  laboratory  rabbits  are  suitable.  Three 
or  four  injections  into  the  ear  vein  of  the  rabbit,  spaced  at  intervals 
of  8  or  10  days  with  cultures  of  cholera  or  typhoid,  will  develop  ag- 
glutinins in  the  blood  serum  when  diluted  as  high  as  1  to  5,000  or  1  to 
10,000.  Where  large  amounts  are  needed  the  horse  is  the  most  suitable 
animal. 

Agglutinins  also  appear  spontaneously  in  attacks  of  certain  infec- 
tious diseases  and  continue  in  the  blood  for  some  time  after  convales- 
cence. In  typhoid  fever  they  appear  about  the  end  of  the  first  week. 
They  are  usually  weak  at  first,  clumping  the  typhoid  bacilli  in  a  dilu- 
tion of  1-30  in  one  hour  at  the  body  temperature,  and  increase  with 
the  progress  of  the  disease,  so  that  the  serum  may  agglutinate  in  dilu- 
tions of  1-1,000  or  more.  In  malta  fever  agglutinins  appear  about  the 
fifth  day  of  the  disease  and  may  develop  in  large  amount.  Thus,  the 
blood  serum  from  a  case  of  malta  fever  may  agglutinate  the  Micrococcus 
melitensis  in  dilutions  as  high  as  1-500,000.  The  reaction  of  agglu- 
tination is  not  only  practical  as  an  aid  to  diagnosis  of  disease,  but  is 
of  considerable  practical  use  as  an  aid  of  recognition  of  the  bacteria 
themselves.  Agglutinins  are  also  produced  in  man  by  the  inoculation  of 
bacterial  vaccines. 

The  reaction  of  agglutination  is  not  absolutely  specific;  thus,  a  ty- 
phoid agglutinin  will  occasionally  clump  proteus  or  other  not  very 
closely  related  microorganisms.  Thus,  Frost  found  a  Psedomonas  pro- 
tea  in  the  Potomac  Eiver  water  that  showed  quite  constantly  the  char- 
acteristic of  being  agglutinated  by  specific  typhoid  immune  serum. 
However,  when  animals  were  injected  with  the  Ps.  protea  they  developed 
agglutinins  for  this  organism,  but  not  for  the  B.  typhosus.  Further, 
there  is  the  phenomenon  of  group  agglutination  or  group  reaction; 
that  is,  typhoid  serum  will  clump  the  colon  bacillus,  the  paratyphoid, 
the  paracolon  bacillus,  and  closely  related  organisms  in  the  colon  ty- 
phoid group.  However,  this  occurs  only  in  weak  dilutions.  The  reac- 
tion is,  therefore,  specific  in  a  quantitative  sense.  Thus,  a  good  cholera 
or  typhoid  serum  will  agglutinate  these  organisms  in  dilutions   of  1- 


ANAPHYLAXIS  457 

1,000  and  over,  whereas  the  group  reactions  occur  in  dilutions  of  about 
1-50  or  less. 

In  addition  to  the  bacteria,  the  red  blood  cells,  or  cells  of  any 
sort,  trypanosomes  and  other  protozoa  may  be  agglutinated. 

We  have  no  satisfactory  explanation  of  agglutination.  Analogous 
phenomena  occur  in  the  study  of  the  physical  chemistry  of  colloidal 
substances.  It  seems  that  in  agglutination  two  separate  phenomena  are 
involved:  the  approach  of  the  particles,  one  to  the  other,  and  their  ad- 
hesion subsequently.  The  phenomenon  may  be  imitated  by  coating 
match  sticks  with  soap,  floating  them  upon  the  surface  of  water,  in  a 
basin,  and  then  adding  sulphuric  acid.  The  agglutinins  affect  the  sur- 
face tension  between  the  bacteria  and  the  fluid  in  which  they  are  sus- 
pended in  some  way,  but  just  how  is  not  quite  clear.  The  agglutinins 
are  probably  formed  in  the  lymphoid  organs,  red  marrow,  and  spleen; 
at  least,  Pfeiffer  and  Marx  found  them  early  in  these  organs  after 
injections  of  cholera  vibrios.  Metchnikoff  found  that  the  peritoneal 
exudate  may  be  richer  in  agglutinins  than  the  blood,  and  believes  in 
that  fluid  they  come  from  the  leukocytes  and  endothelial  cells. 

The  part  played  by  the  agglutinins  in  immunity  is  not  clear.  Al- 
though the  bacteria  are  immobilized,  this  does  not  particularly  favor 
phagocytosis.  Large  clusters  of  bacteria  or  agglutinated  clumps  of 
closely  packed  cells  afford  a  mechanical  protection  against  the  dissolv- 
ing action  of  the  lysins. 

ANAPHYLAXIS 

Anaphylaxis  (ana,  against,  and  pliylax,  guard,  or  phylaxis,  protec- 
tion), also  called  hypersusceptibility,  is  a  condition  of  unusual  or  exag- 
gerated susceptibility  of  the  organism  to  foreign  proteins.  In  other 
words,  anaphylaxis  is  an  altered  power  of  reaction  on  the  part  of  the 
body  to  foreign  proteins.  The  word  anaphylaxis  was  introduced  by 
Richet  to  describe  a  condition  contrary  to  prophylaxis.  As  we  now 
regard  the  phenomenon,  the  word  is  a  misnomer,  for  we  look  upon  the 
condition  of  hypersusceptibility  as  a  distinct  benefit  and  advantage  to 
the  organism;  in  fact,  immunity  against  a  large  class  of  infectious 
diseases  probably  depends  upon  an  altered  power  of  reaction,  that  is, 
upon  hypersusceptibility  or  anaphylaxis. 

The  condition  of  anaphylaxis  may  be  congenital  or  acquired,  local  or 
general,  and  is  specific  in  nature.  It  may  be  brought  about  by  the  intro- 
duction of  any  strange  protein  into  the  body.  Hypersusceptibility  to 
proteins  that  are  non-poisonous '  in  themselves  may  readily  be  induced 
in  certain  animals.  The  animal  may  be  in  a  condition  of  hypersuscepti- 
bility and  immunity  at  the  same  time.  The  two  conditions  are  closely 
interwoven.      The   latter   is   often   dependent   upon   the   former.      Von 


458  IMMUNITY 

Pirquet  suggests  the  term  "allergie"  to  indicate  cojiditioiis  of  acquired 
immunity  associated  with  anaphylaxis.  Allergic,  as  the  word  indicates 
{alios,  change,  and  ergon,  action),  is  an  altered  power  of  the  organism 
to  react.  When  this  power  of  reaction  is  increased  we  say  the  body  is 
hypersusceptible,  or  in  a  state  of  anaphylaxis. 

Examples  of  Anaphylaxis. — In  the  case  of  vaccinia,  the  reaction  to  a 
primary  "take"  appears  after  an  incubation  of  four  days.  In  a  secondary 
vaccination  the  period  of  incubation  is  shortened  and  the  clinical  reac- 
tion lessened.  In  other  words,  the  power  of  the  organism  to  react  is 
changed.  This  power  of  accelerated  or  immediate  reaction  protects  the 
individual.  Therefore,  there  is  no  absolute  immunity  in  the  class  of  dis- 
eases represented  by  smallpox;  the  prophylaxis  depending  upon  the 
anaphylaxis. 

The  tuberculin  and  mallein  reactions  are  well-known  instances  of 
anaphylaxis.  These  substances  are  not  poisonous  when  introduced  into 
a  healthy  individual,  but  the  tuberculous  individual  is  anaphylactic  to 
tuberculin,  and  an  individual  suffering  from  glanders  is  in  a  state  of 
hypersusceptibility  to  mallein. 

A  clinical  instance  of  anaphylaxis  is  the  hypersusceptibility  of  some 
individuals  to  pollen — hay  fever.  Other  examples  are,  food  "idiosyn- 
crasies", serum  sickness,  urticarial  and  other  skin  eruptions. 

Experimental  anaphylaxis  may  be  brought  about  in  various  ways,  such 
as  the  introduction  of  an  alien  serum  into  the  body — serum  anaphylaxis. 

Experimental  Serum  Anaphylaxis. — The  essential  features  of  experi- 
mental anaphylaxis  are : 

(1)  The  first  injection,  consisting  of  a  bland  alien  protein  non- 
poisonous  in  itself,  which  sensitizes  the  animal ; 

(2)  An  interval  of  about  8  to  14  days; 

(3)  The  second  injection  of  the  same  protein  which  produces  a 
reaction  known  as  acute  anaphylactic  shock. 

Horse  serum,  when  injected  into  normal  guinea-pigs,  causes  no 
symptoms.  As  much  as  20  c.  c.  may  be  injected  into  the  peritoneal 
cavity  of  a  guinea-pig  without  causing  any  apparent  inconvenience 
to  the  animal.  Small  amounts  of  horse  serum  may  even  be  injected 
directly  into  the  brain  without  causing  any  untoward  symptoms. 

Very  characteristic  symptoms,  however,  are  produced  by  horse  serum 
when  injected  into  a  susceptible  guinea-pig;  i.  e.,  one  that  has  received 
a  prior  injection  of  horse  serum.  In  five  or  ten  minutes  after  injection 
the  pig  becomes  restless  and  then  manifests  indications  of  respiratory 
embarrassment  by  scratching  at  the  mouth,  coughing,  and  sometimes  by 
spasmodic,  rapid,  or  irregular  breathing;  the  pig  becomes  agitated  and 
there  is  a  discharge  of  urine  and  feces.     This  stage  of  exhilaration  is 


ANAPHYLAXIS  459 

soon  followed  by  one  of  paresis  or  complete  paralysis,  with  arrest  of 
breathing.  The  pig  is  unable  to  stand  or,  if  it  attempts  to  move,  falls 
upon  its  side ;  when  taken  up  it  is  limp :  spasmodic,  jerky,  and  con- 
vulsive movements  now  supervene.  This  chain  of  symptoms  is  very 
characteristic,  although  they  do  not  always  follow  in  the  order  given. 
Pigs  in  the  stage  of  complete  paralysis  may  fully  recover,  but  usually 
convulsions  appear,  and  are  almost  invariably  a  forerunner  of  death. 
Symptoms  appear  about  ten  minutes  after  the  injection  has  been  given; 
occasionally  in  pigs  not  very  susceptible  they  are  delayed  thirty  to  forty- 
five  minutes.  Pigs  developing  late  symptoms  are  not  very  susceptible 
and  do  not  die.  Death  usually  occurs  within  an  hour  and  frequently  in 
less  than  thirty  minutes.  If  the  second  injection  be  made  directly 
into  the  brain  or  circulation,  the  symptoms  are  manifested  with  explosive 
violence,  the  animal  frequently  dying  within  two  or  three  minutes. 

A  fall  in  temperature  occurs  which  in  fatal  cases  may  be  as  great 
as  13°  C.  (Pfeiffer).  The  blood  during  anaphylactic  shock  shows  a 
leukopenia  and  a  diminution  in  complement.  The  blood  pressure  falls. 
When  the  chest  is  opened  the  lungs  show  a  striking  condition  resembling 
emphysema.  They  do  not  collapse  but  remain  fully  distended,  forming 
a  cast  of  the  pleural  cavities.  The  heart  continues  to  beat  long  after 
respiration  has  ceased.  Asphyxia,  due  to  inspiratory  immobilization  of 
the  lungs,  is,  therefore,  probably  the  immediate  cause  of  death. 

Judged  by  the  severity  of  the  symptoms  of  the  acute  anaphylactic 
reaction,  the  guinea-pig  is  apparently  the  most  susceptible  of  animals 
(being  400  times  more  sensitive  than  the  rabbit,  according  to  Doerr), 
but  probably  all  animals  may  be  sensitized  to  a  greater  or  less  degree, 
although  our  methods  of  observation  are  still  too  crude  to  admit  of 
any  accurately  graded  comparison.  White  mice  were  long  thought  to  be 
non-responsive  on  account  of  the  absence  of  anaphylactic  shock  and 
death  from  asphyxia,  so  striking  in  the  guinea-pig;  but  Schultz  and 
Jordan  have  shown  that  white  mice  do  react  toward  horse  serum  with 
restlessness,  marked  irritability  of  the  skin,  passage  of  urine  and  feces, 
and  temperature  and  blood  pressure  changes. 

In  dogs,  according  to  Eichet,  the  principal  symptoms  are  gastro- 
intestinal. There  is  immediate  vomiting,  followed  by  tenesmus  and 
bloody  discharges  from  the  intestines.  Death  is  infrequent,  but  there 
may  develop  a  condition  of  hemorrhagic  inflammation  in  both  the  large 
and  the  small  intestine  which  is  called  by  Eichet  "chronic  anaphylaxis," 
and  by  Schittenhelm  and  Weichardt,  "enteritis  anaphylactica."  Another 
important  sign  is  the  rapid  fall  in  blood  pressure,  sometimes  80-100 
mm. ;  coagulation  of  the  blood  is  delayed.  Dyspnea  is  not  marked,  but, 
as  in  other  animals,  there  is  initial  restlessness  and  skin  irritability ; 
there  may  be  paralysis  and  death. 

Eabbits  are  apt  to  react  to  a  re-injection  of  horse  serum  by  edema 


460  IMMUNITY 

and  even  necrosis  at  the  site  of  injection — the  "Arthus  phenomenon,"  a 
local  anaphylaxis.  Arthus  also  described,  in  non-fatal  cases  in  rabbits, 
respiratory  disturbance,  general  prostration,  fall  in  blood-pressure,  and 
increased  peristalsis.  In  cases  of  acute  lethal  anaphylaxis  produced  in 
rabbits  highly  sensitized  by  repeated  minute  injections,  Auer  describes 
the  slow  respiration,  the  sudden  falling  of  the  animal  on  its  side  with  a 
short  clonic  convulsion,  stoppage  of  the  respiration,  weak  heart  beat, 
and  death  within  a  few  minutes. 

The  reaction  to  a  second  injection  of  serum  has  been  observed,  though 
not  studied  so  carefully,  in  numerous  other  animals,  e.  g.,  in  cows,  horses, 
goats,  sheep,  and  cats,  in  hens  and  pigeons,  and  in  certain  cold-blooded 
animals,  with  symptoms  varying  according  to  the  species. 

It  is  evident  that  no  one  symptom,  or  group  of  symptoms,  can  be 
taken  as  an  adequate  criterion  of  anaphylaxis  in  all  cases.  Different 
species  give  a  widely  differing  picture  with  the  same  proteid  agent, 
because  the  same  organs  are  not  involved  to  the  same  degree.  An  ex- 
planation of  these  differences  from  the  physiological  point  of  view  has 
been  given  by  Schultz.  He  has  shown  that  serum  anaphylaxis  is  essen- 
tially a  matter  of  hypersensitization  of  smooth  muscle  in  general.  He 
concludes,  as  a  result  of  his  experiments,  that,  during  anaphylactic 
shock,  all  smooth  muscle  contracts.  This  is  fatal  to  the  guinea-pig, 
owing  to  the  peculiar  though  normal  anatomical  condition  of  its  bron- 
chial tree :  the  mucosal  layer  of  the  secondary  bronchi  is  relatively  thick 
in  comparison  with  the  lumen,  and  the  contraction  of  the  smooth  muscle 
throws  it  into  folds  which  completely  occlude  the  bronchi  (Schultz  and 
Jordan).  The  guinea-pig  dies  of  asphyxia,  the  cause  of  which  is  purely 
local  and  not  in  the  central  nervous  system,  as  the  first  investigators  be- 
lieved. The  bronchi  of  mice,  dogs,  and  rabbits,  however,  are  relatively 
poor  in  smooth  muscle,  which  accounts  for  the  almost  complete  ab- 
sence of  death  from  asphyxia.  In  the  dog  the  contraction  of  smooth 
muscle  sets  up  a  vigorous  intestinal  peristalsis  and  a  forced  emptying 
of  the  urinary  bladder;  the  characteristic  initial  rise  in  blood  pressure 
may  be  due  to  constriction  of  the  pulmonary,  coronary  and  systemic 
arteries,  and  according  to  Auer,  the  subsequent  marked  fall  to  direct 
action  on  the  heart  muscle  itself,  particularly  of  the  right  side,  causing 
a  venous  accumulation  of  blood,  an  effect  typified  most  strikingly  in 
the  rabbit.  This  provides  also  an  adequate  pharmacological  explanation 
of  the  action  of  atropin  and  the  anesthetics  in  alleviating  the  symptoms 
of  acute  anaphylaxis. 

Specificity. — The  anaphylactic  reaction  is  specific.  Thus,  a  guinea- 
pig  sensitized  with  horse  serum  does  not  react  to  a  subsequent  injection 
of  egg-white,  vegetable  proteid,  or  milk.  The  specificity  extends  even 
further  than  this.  In  order  to  give  rise  to  anaphylactic  symptoms,  the 
proteid  material  given  at  the  first  and  second  injections  must  be  from 


ANAPHYLAXIS  461 

the  same  species  or  from  some  closely  related  species.  Thus  a  guinea- 
pig  sensitized  with  cow's  milk  will  not  react  to  a  subsequent  injection 
of  woman's  milk.  Guinea-pigs  sensitized  with  the  albumen  of  hen's 
eggs  will  not  react  to  a  subsequent  injection  of  the  albumen  of  the  eggs 
of  pigeons,  but  do  react  mildly  to  duck  egg-white.  This  specificity  ac- 
cording to  species  is,  therefore,  of  the  same  degree  as  that  of  certain 
immune  reactions,  notably  the  precipitins;  that  is,  there  is  a  group 
reaction  in  the  proteids  of  allied  species,  but  no  reaction  between  the 
proteids  of  widely  different  species  or  between  proteids  of  widely  dif- 
ferent origin.  The  maximum  effect  at  second  injection  is  obtained 
by  the  use  of  the  identical  proteid  used  for  sensitization.  Certain 
sera  which  react  interchangeably  to  precipitins,  as,  for  example,  human 
and  ape,  horse  and  ass,  sheep  and  goat,  rat  and  mouse,  remain  indis- 
tinguishable also  by  the  anaphylactic  reaction.  The  same  specificity 
holds  with  respect  to  bacterial  proteids :  an  animal  sensitized  with  typhoid 
bacilli  will  react  strongly  toward  paratyphoid,  and  somewhat  toward  colon 
bacilli,  but  not  at  all  to  unrelated  species. 

One  of  the  remarkable  facts  in  relation  to  the  specificity  of  anaphy- 
laxis is  that  guinea-pigs  may  be  in  a  condition  of  anaphylaxis  to  three 
proteid  substances  at  the  same  time ;  for  instance,  a  guinea-pig  may  be 
sensitized  with  egg-white,  milk,  and  horse  serum,  and  subsequently  react 
separately  to  a  second  injection  of  each  one  of  these  substances.  The 
guinea-pig  may  be  sensitized  by  giving  these  strange  proteids  either  at 
the  same  time  or  different  times,  in  the  same  place  or  in  different  places, 
or  by  injecting  them  separately  or  mixed.  The  guinea-pig  differentiates 
each  anaphylactogenic  protein  in  a  perfectly  distinct  and  separate  man- 
ner. The  animal  is  susceptible  to  the  second  injection  of  each  one  of  the 
three  substances  in  the  same  sense  that  it  is  susceptible  to  three  separate 
infectious  diseases. 

That  there  may  be  exceptions  to  the  rule  of  species-specificity  is  shown 
in  the  case  of  the  crystalline  lens.  A  guinea-pig  sensitized  to  the  lens- 
extract  of  one  species  of  animal  will  react  to  the  lens-extract  of  widely 
different  species,  or  even  of  its  own  species,  but  not  to  other  tissues 
(Andrejew).  Here,  too,  there  is  an  exact  parallel  in  the  precipitin 
reaction  which  fails  to  distinguish  the  lens  of  one  .species  from  that  of 
another  (Uhlenhuth).  This  is  an  example  of  organ-specificity.  In  the 
vegetable  world  Osborne  has  shown  that,  whereas  preparations  of  globu- 
lins from  hemp,  flax,  and  squash  do  not  react  with  each  other,  gliadin 
from  rye  reacts  strongly  with  gliadin  from  wheat,  a  result  in  accord 
with  the  fact  that  by  chemical  and  physical  means  no  differences  have 
been  detected  which  were  sufficient  to  indicate  that  these  gliadins  were 
different  substances. 

It  is  probable  that  only  proteids  which  have  a  complete  or  partial 
chemical  identity  of  structure  will  react  with  each  other.     Differences 


463  IMMUNITY 

too  small  to  be  detected  by  analytic  means  at  our  di.spo.sal  may  yet  pre- 
vent any  tendency  toward  interaction,  and  the  anaphylactic  phenomenon 
may  thus  be  used  to  determine  the  finer  relationships  of  proteids.  It  is 
evident  from  these  facts,  as  Osborne  concludes,  that  structural  differences 
exist  between  very  similar  proteins  of  different  origin,  and  that  chemi- 
cally identical  proteins  apparently  do  not  occur  in  animals  and  plants 
of  different  species  unless  they  are  biologically  very  closely  related. 

Sensitization  by  Feeding. — Guinea-pigs  may  be  sensitized  by  feeding 
them  meat  or  serum.  The  fact  that  guinea-pigs  may  be  rendered  sus- 
ceptible by  the  feeding  of  strange  protein  matter  opens  an  interesting 
question  as  to  whether  sensitive  guinea-pigs  may  also  be  poisoned  by 
feeding  with  the  same  protein  given  after  a  proper  interval  of  time.  If 
man  can  be  sensitized  in  a  similar  way  by  the  eating  of  certain  protein 
substances,  this  may  throw  light  on  those  interesting  and  obscure  cases 
in  which  the  eating  of  fish,  sea  food,  or  other  articles  of  diet  sometimes 
causes  sudden  and  often  serious  symptoms  resembling  those  of  anaphy- 
laxis in  all  essential  respects. 

Maternal  Transmission. — It  has  been  found  that  hypersusceptibility 
to  the  toxic  action  of  horse  serum  is  transmitted  from  the  mother 
guinea-pig  to  her  young.  This  function  is  solely  maternal;  the  male 
takes  no  part  whatever  in  the  transmission  of  these  acquired  properties. 
Whether  this  maternal  transmission  is  hereditary  or  congenital  cannot 
be  definitely  stated. 

There  are  certain  analogies  between  the  action  of  tuberculosis  and 
anaphylaxis.  Both  produce  hypersensitiveness  and  also  a  certain  de- 
gree of  immunity.  Now  that  it  has  been  proved  that  hypersensitive- 
ness or  anaphylactic  action  may  be  transmitted  in  guinea-pigs,  may  it 
not  throw  light  upon  the  fact  that  tuberculosis  "runs  in  families"? 
While  there  are  several  recorded  instances  demonstrating  that  immunity 
to  certain  infectious  diseases  may  be  transmitted  from  a  mother  to  her 
young,  this  is,  so  far  as  is  known,  the  only  recorded  instance  in  which 
hypersensitiveness  or  a  tendency  to  a  disease  has  been  experimentally 
shown  to  be  transmitted  from  a  mother  to  her  young. 

Serum  Anaphylaxis  in  Man,  or  Serum  Sickness. — Serum  anaphylaxis 
in  man  is  met  with  most  frequently  following  the  use  of  antitoxic  sera, 
and  has  been  carefully  described  by  v.  Pirquet  and  Schick  (1905).^ 
After  an  injection  of  serum  (usually  in  from  eight  to  twelve  days)  there 
is  apt  to  be  a  febrile  reaction,  now  generally  known  as  "serum-sickness," 
or  serum  disease.  The  common  symptoms  are  local  redness,  itching  and 
pain  at  the  point  of  injection,  swelling  of  the  lymph  nodes,  fever,  and 
a  general  urticaria  lasting  from  two  to  six  days.  In  more  severe  cases 
there  is  malaise,  albuminuria,  pronounced  joint  pains  and  even  effusions, 
swelling  of  the  mucous  membranes,  hoarseness  and  cough,  nausea  and 

'  "Serum  Krankheit,"  Wien,  1905. 


ANAPHYLAXIS  463 

vomiting,  vertigo,  and  remarkable  skin  manifestations  varying  from 
hyperemias  and  erythemas  to  efflorescences  resembling  measles  or  scar- 
latina, and  other  vasomotor  disturbances. 

Earely  there  may  be  subnormal  temperature,  a  weak  and  rapid  pulse, 
a  catarrhal  or  hemorrhagic  enteritis  and  extreme  weakness  approaching 
collapse.  These  results  are  independent  of  the  antitoxic  qualities  of 
the  serum,  for  Johannessen  obtained  the  same  symptoms  by  introducing 
normal  horse  serum  into  the  bodies  of  perfectly  healthy  human  beings. 
Indeed,  the  very  earliest  animal  experiments  were  particularly  concerned 
in  determining  whether  the  antitoxin  played  any  part  in  the  phenomenon, 
and  it  was  soon  conclusively  eliminated  as  a  factor. 

Both  the  incidence  and  the  severity  of  serum  sickness  are  propor- 
tional to  the  amount  injected  up  to  a  certain  point,  but  the  acute 
(sometimes  fatal)  reaction  in  man  is  more  dependent  upon  the  hyper- 
susceptibility  of  the  individual  than  upon  the  amount  of  serum  injected. 
If  the  serum  is  "concentrated"  (i.  e.,  serum-globulin),  the  reactions  are 
correspondingly  lessened  because  smaller  quantities  of  the  foreign  pro- 
teid  are  injected,  the  albumens  and  certain  other  proteins  having  been 
eliminated  by  the  partial  purification. 

The  peculiarity  of  serum  sickness  in  man  is  that  it  may  follow 
the  first  injection  of  a  foreign  serum,  though  only  after  a  definite  incu- 
bation period  corresponding  to  the  time  required  to  sensitize  an  experi- 
mental animal.  There  is  no  proof  that  other  animals  do  not  develop 
a  reaction  to  the  first  dose  which  never  rises  to  the  threshold  of  clinical 
observation;  in  fact,  Ehrlich,  Francione,  and  others  have  observed  a 
temporary  diminution  of  complement  in  the  blood  of  guinea-pigs  10-12 
days  after  the  first  injection. 

Besides  the  typical  serum  sickness,  there  has  been  reported  since 
the  introduction  of  serum  therapy  a  certain  small  number  of  unforeseen 
and  fatal  catastrophes  attending  the  injection  of  serum  into  human 
beings.  The  following  case  published  by  H.  F.  Gillette  will  serve  to 
illustrate  them  all : 

"The  patient  was  a  man  of  52,  a  subject  of  asthma.  He  asked 
me  to  administer  diphtheria  antitoxin  to  him,  hoping  it  might  cure 
his  asthma.  I  administered  2,000  units  under  the  left  scapula  with 
the  usual  precautions.  He  had  about  completed  dressing  when  he  said 
he  had  a  pricking  sensation  in  the  neck  and  chest;  soon  he  sat  down 
and  said  he  could  not  breathe,  nor  did  he  breathe  again.  .  .  .  His 
pulse  at  the  wrist  remained  regular  and  full  for  some  time  after  respira- 
tion ceased.  He  had  a  mild  degree  of  cyanosis  and  edema  of  the  face. 
He  died  in  tonic  spasms  ten  minutes  after  injection.  Autopsy  revealed 
no  palpable  cause  of  death." 

The  same  author  collected  28  cases  of  collapse  or  death  after  serum 
injection,  of  which  15  died.     There  was  a  common  history  of  previous 


464  IMMUNITY 

asthmatic  trouble  in  all  but  five  of  the  28,  and  all,  after  injection, 
showed  common  symptoms  of  sudden  intense  dyspnea,  a  sense  of  over- 
whelming anxiety,  edema  and  cyanosis  of  the  face,  a  sudden  massive 
urticaria,  tonic  muscular  spasms  and  continued  beating  of  the  heart 
long  after  the  ceasing  of  respiration.  Eosenau  and  Anderson  collected 
19  cases  and  were  able  to  examine  the  serum  used  in  two  of  them.  It 
was  found  to  be  no  more  toxic  to  sensitized  guinea-pigs  than  normal 
horse  serum.  These  cases  of  severe  anaphylactic  shock  seem  susceptible 
of  no  other  explanation  than  that  the  unfortunate  individuals  had  been 
in  some  manner,  at  a  previous  time,  sensitized  to  horse  protein.  They 
present  a  picture  which  is  almost  the  counterpart  of  typical  anaphylactic 
shock  in  guinea-pigs,  and  the  most  striking  thing  about  them  is  that 
practically  all  give  a  history  of  respiratory  trouble  in  the  past,  especially 
horse-asthma.  Schultz  and  Jordan  suggest  that  these  occasional  cases 
of  sudden  death  in  man  may  perhaps  be  due  to  an  abnormal  develop- 
ment of  the  mucous  membrane  and  smooth  muscle  of  the  bronchi  (as  in 
asthmatics),  and  that  the  smooth  muscle,  being  hypersusceptible,  pro- 
duces asphyxia  by  sudden  contraction.  Eosenau  and  Amoss  ^  have  re- 
cently indicated  a  possible  explanation  of  the  way  in  which  such  persons 
may  become  sensitized.  They  have  proved  that  a  protein  material  is 
given  off  in  the  expired  breath  of  human  beings.  There  is  some  reason 
to  suppose  that  the  protein  given  off  by  one  animal  may  be  absorbed 
by  individuals  of  different  species  by  way  of  the  lungs.  One  thing  is 
clear,  that  these  immediate  and  sometimes  fatal  reactions  are  not  de- 
pendent upon  any  peculiar  property  in  the  serum,  but  to  an  altered 
power  of  reaction  of  the  individual  to  the  foreign  protein  injected. 
The  anaphylactic  reactions  following  the  injection  of  serum  in  man  may 
be  summed  up  briefly  as  follows : 

Reactions  following  first  injection: 

(a)  "^Serum  sickness,^'  incubation  8-12  days  (common). 

(b)  Acute  anaphylactic  shock,  with  collapse  or  death  (rare). 
Reactions  following  second  injection : 

(a)  Interval  between  injections  less  than  8  days,  no  reaction. 

(b)  Interval  12-40  days,  immediate  reaction. 

(c)  Interval  15  days-6  mos.,  either  immediate  or  accelerated  reaction, 
or  both. 

(d)  Interval  over  6  mos.,  accelerated  reaction. 

The  above  table  represents  the  usual  course  of  events,  but  exceptions 
may  occur,  and  the  time  intervals  are  only  approximate.  Sometimes  the 
reactions  do  not  appear  until  the  third,  fourth,  or  some  subsequent 
injection. 

*  Eosenau,  M.  J.,  &  Amoss,  H.  L.:  Jour,  of  Med.  Res.,  Sept.,  1911,  XXV, 
1,  pp.  35-84. 


ANAPHYLAXIS  465 

The  following  precautions  are  suggested  in  serum  therapy : 

(1)  Except  in  urgent  cases,  avoid  injecting  horse  serum  into  indi- 
viduals known  to  be  asthmatic,  especially  those  whose  symptoms  are 
brought  on  by  being  around  horses. 

(2)  If  hypersensitiveness  is  suspected,  give  at  first  a  very  small 
portion  of  the  dose,  following  it  in  an  hour  or  so  with  the  rest,  injecting 
it  exceedingly  slowly  and  avoiding  direct  injection  into  the  circulation. 

(3)  In  persons  known  or  suspected  of  being  hypersusceptible  to  horse 
serum,  bovine  antitoxin  may  be  used. 

Hypersusceptibility  and  Immunity  Produced  by  Bacterial  Proteins. 
— The  problem  of  hypersusceptibility  has  an  important  bearing  on  the 
question  of  immunity,  and  hence  the  opinion  has  been  expressed  that 
"resistance  to  disease  may  largely  be  gained  through  a  process  of  hyper- 
susceptibility. Whether  this  increased  susceptibility  is  an  essential  ele- 
ment or  only  one  stage  in  the  process  of  resistance  to  disease  must 
now  engage  our  attention."  We  cannot  escape  the  conviction  that  this 
phenomenon  of  hypersusceptibility  has  an  important  bearing  on  the 
prevention  and  cure  of  certain  infectious  processes. 

Hypersusceptibility  may  easily  be  induced  in  guinea-pigs  with  pro- 
tein extracts  obtained  from  the  bacterial  cell.  The  first  injection  of 
most  of  the  extract  seems  comparatively  harmless  to  the  animal.  A 
second  injection  of  the  same  extract  shows,  however,  that  profound 
physiologic  changes  have  taken  place.  A  definite  period  must  elapse 
between  the  first  and  the  second  injection.  The  symptoms  presented 
by  the  guinea-pigs  as  a  result  of  the  second  injection  resemble  those 
caused  by  other  proteins.  The  phenomenon  induced  by  a  second  injec- 
tion is  followed  (in  certain  cases)  by  an  immunity  to  the  correspond- 
ing infection. 

These  results  strengthen  the  belief  that  the  phenomenon  of  hyper- 
susceptibility has  a  practical  significance  in  the  prevention  and  cure 
of  certain  infectious  processes.  It  also  gives  a  possible  explanation  of 
the  period  of  incubation  of  some  of  the  communicable  diseases.  Is  it 
a  coincidence  that  the  period  of  incubation  of  a  number  of  infectious 
diseases  is  about  ten  to  fourteen  days,  which  corresponds  significantly 
with  the  time  required  to  sensitize  animals  with  a  strange  protein  ? 

In  certain  infectious  diseases  with  short  periods  of  incubation,  such 
as  pneumonia,  the  crisis  which  commonly  appears  about  the  tenth  day 
may  find  a  somewhat  similar  explanation.  It  is  evident  that  disease 
processes  produced  by  soluble  toxins,  such  as  diphtheria  and  tetanus, 
do  not  belong  to  the  category  now  under  consideration. 

Relation  of  Anaphylaxis  to  Protein  Metabolism. — The  whole  prob- 
lem of  protein  metabolism  seems  to  be  an  adjustment  in  the  sense  of  a 
defense.  The  power  to  assimilate  and  use  foreign  proteins  is  not 
achieved  without  a  certain  amount  of  violence  to  the  body.     The  rela- 


466  IMMUNITY 

tion  between  the  fundamental  facts  of  protein  metabolism  and  immunity 
to  certain  diseases  becomes  clearer  in  the  light  of  observations  upon 
anaphylaxis.  A  deeper  insight  into  these  problems  will  throw  light  on 
the  fundamental  processes  concerned  in  both  protein  metabolism  and 
immunity. 

Relation  of  Anaphylaxis  to  Endotoxins. — The  fact  that  the  great 
majority  of  bacteria  do  not  produce  soluble  poisons,  such  as  diphtheria 
and  tetanus,  has  led  to  the  belief  that  in  such  cases  we  are  dealing  with 
an  "endotoxin."  The  endotoxin  has  long  been  regarded  as  a  poisonous 
substance  so  intimately  associated  with  the  cell  that  it  is  not  released 
until  the  microbic  cell  is  broken  up  in  the  body.  The  inability  to  dem- 
onstrate many  of  these  endotoxins  has  cast  a  doubt  on  their  existence  and 
increased  the  mystery  of  their  action.  It  now  seems  probable  that  the 
studies  on  anaphylaxis  may  throw  light  upon  this  question. 

When  bacteria  grow  in  the  body  they  are  dissolved  by  lytic  agencies 
and  the  foreign  protein  in  the  individual  germ  cells  may  sensitize  the 
body  and  afterward  poison  it.  The  bacterial  proteins  may  not  be  poi- 
sonous in  themselves  in  the  sense  of  an  "endotoxin."  We  have,  in  fact, 
shown  that  protein  extracts  of  bacterial  cells  at  the  second  injection  may 
produce  characteristic  symptoms,  and  this  reaction  may  be  followed 
by  an  immunity  to  the  corresponding  infection. 

The  Relation  of  Anaphylaxis  to  Tuberculosis. — The  tuberculin  reac- 
tion is  one  of  the  best  known  instances  of  anaphylaxis.  The  reaction 
may  be  general,  local  or  focal ;  even  anaphylactic  shock  may  occur.  The 
general  reaction  is  manifested  by  fever  and  constitutional  symptoms ;  the 
local  reaction  by  inflammation  of  the  skin  (von  Pirquet  test)  ;  the  focal 
reaction  by  congestion  about  the  tuberculous  lesion.  Balwin  and  Krause 
have  demonstrated  that  the  general,  local  or  focal  reactions  occur  only 
as  a  result  of  an  anatomical  tubercle.  Following  a  local  infection  with 
the  tubercle  bacillus  the  tissues  generally  become  hypersusceptible  to 
tuberculin.  It  has  been  shown  that  a  local  hypersusceptibility  may  be 
produced  by  the  direct  application  of  tuberculin  to  certain  tissues  (con- 
junctiva). The  same  has  been  demonstrated  for  the  skin,  and  is  prob- 
ably true  of  other  tissues.  This  hypersusceptibility  of  the  tissues 
immediately  surrounding  a  tuberculous  focus  helps  to  encapsulate  and 
limit  the  process.  Should  a  tubercle  bacillus  lodge  in  or  on  a  tissue 
in  a  state  of  tuberculin  anaphylaxis,  the  result  is  that  all  of  nature's 
■protecting  agencies  are  quickly  concentrated  on  the  point  where  most 
needed.  We  conceive  that  this  active  power  of  reacting  quickly  is  not 
only  an  important  factor  in  individual  prophylaxis  against  tuberculosis, 
but  is  an  important  agency  by  which  the  spread  of  the  disease  after  it 
has  obtained  a  lodgment  in  the  body  is  prevented. 

The  normal  individual  does  not  react  to  tuberculin.  The  tubercu- 
lous individual  reacts  promptly,  except  in  the  final  stage  of  the  disease. 


ANAPHYLAXIS  467 

The  difference  between  the  normal  individual  and  the  individual  in 
the  final  stage  of  tuberculosis  is  that  the  former  has  not  had  his  ana- 
phylactic powers  developed,  while  the  latter  has  had  them  developed 
and  exhausted.  A  tuberculous  individual  in  whom  the  specific  power 
of  hypersusceptibility  to  the  poisons  of  the  tubercle  bacillus  is  broken 
down  presents  little  or  no  resistance  against  the  advance  of  the  in- 
fection. 

We  may  adduce  a  practical  lesson  from  this.  When  tuberculin  is 
used  in  large  or  too  oft-repeated  doses  there  is  a  tendency  to  break 
down  or  to  exhaust  the  useful  and  beneficial  hypersusceptible  state  of 
the  tissues.  In  accordance  with  this  line  of  reasoning,  therefore,  tuber- 
culin would  be  of  benefit  in  tuberculosis  only  when  used  in  such  a  way 
as  to  develop  and  not  diminish  the  power  of  anaphylaxis  of  the  tissues. 
This  explanation  has  been  borne  out  in  the  use  of  tuberculin,  especially 
as  a  therapeutic  agent  in  bone,  gland  and  skin  tuberculosis,  when  the 
process  is  sluggish. 

Relation  of  Anaphylaxis  to  Vaccination. — When  the  virus  of  cowpox 
is  introduced  into  the  skin  we  implant  a  colony  of  microorganisms.  They 
grow  day  by  day,  and  on  the  eighth  day  there  is  an  enormous  number 
of  them.  The  contents  of  the  vesicle  will  start  new  colonies  on  thou- 
sands of  other  arms,  but  now  the  antibodies  appear  and  the  colony  is 
attacked  and  digested,  and  toxic  bodies  are  formed.  This  is  diffused 
in  the  neighborhood  and  we  get  an  intense  local  inflammation  called  the 
areola.  Some  of  the  toxic  bodies  enter  the  circulation  and  cause  fever, 
but  the  microorganisms  are  killed  and  we  can  no  longer  vaccinate  with 
the  contents  of  the  now  yellow  pustule;  two  or  three  days  more,  the 
struggle  is  over,  but  the  antibodies  remain  a  long  time.  Let  us  now 
revaccinate,  and  a  different  series  of  events  takes  place,  for  in  the  mean- 
time the  body  has  become  educated  and  instead  of  waiting  some  days 
before  attacking  the  colony  of  microorganisms  in  the  skin,  starts  the 
attack  at  once.  In  other  words,  there  is  an  immediate  reaction — a 
changed  power  of  reaction  or  anaphylaxis.  In  brief,  the  first  vaccina- 
tion has  sensitized  the  tissues,  so  that  they  respond  at  once  upon  the 
second  vaccination. 

The  invading  microorganisms,  attacked  at  once,  are  soon  destroyed — 
they  are  given  no  chance  to  multiply,  and  little  toxin  is  formed.  This 
attractive  explanation  of  the  immunity  to  smallpox  or  cowpox,  developed 
by  von  Pirquet,  shows  that  the  prophylaxis  depends  upon  the  anaphy- 
laxis. 

Relation  of  Anaphylaxis  to  Food  "Idiosyncrasies." — Many  persons 
are  susceptible  to  some  particular  article  of  diet.  The  symptoms  pro- 
duced are  vasomotor  disturbances,  skin  eruptions,  gastro-intestinal  dis- 
orders, and  respiratory  difficulty.  The  articles  of  diet  usually  responsible 
are  shell-fish,  fish,  strawberries,  tomatoes,  pork,  cereals,  eggs,  milk, — the 


468  IMMUNITY 

list  is  very  long,  includiBg  even  honey.  Fish,  tomatoes,  and  cheese  are 
apt  to  produce  urticarias;  cereals,  pork  and  milk,  erythemas  and  eczemas; 
eggs,  asthmatic  symptoms.  There  is,  however,  no  constancy  in  this  re- 
gard. Collapse  may  result  in  a  few  minutes  from  the  ingestion  of  a  very 
small  amount  of  the  particular  suhstance  to  which  a  person  is  hyper- 
susceptihle. 

These  cases  of  food  '^idiosyncrasies"  are  instances  of  local  and  general 
anaphylaxis.  In  most  cases  the  susceptibility  is  clearly  inherited,  in 
some  it  may  be  acquired.  When  there  is  difficulty  in  determining  which 
food  is  responsible,  the  skin  test  may  be  employed.  This  consists  in  rub- 
bing a  drop  of  the  food  itself,  or  a  watery  extract,  into  a  scratch  upon 
the  skin.  The  reaction  comes  on  within  thirty  minutes,  as  a  pink-red 
papule,  and  declines  rapidly. 

Eczema. — Towle  and  Talbot  were  among  the  first  to  definitely  reveal 
that  a  goodly  proportion  of  eczematous  infants  were  passing  stools  con- 
taining an  excess  of  fats  and  starch.  A  correction  of  diet  will  relieve 
most  of  these  infants  in  a  few  weeks.  In  cases  where  eczematous  infants 
and  older  children  do  not  reveal  an  excess  of  starch  or  fat,  they  are 
usually  anaphylactic  to  egg  albumin,  milk  or  some  other  protein.  In 
chronic  eczema,  the  great  majority  of  these  victims  exhibit  anaphylactic 
reactions  to  one  or  more  types  of  food  substances.  Only  about  20  per 
cent,  of  eczematous  individuals  do  not  appear  sensitized  to  any  of  the 
common  food  types. 

Relation  of  Anaphylaxis  to  Hay  Fever. — Hay  fever  may  be  caused 
by  the  pollen  of  grasses  and  certain  plants,  such  as  ragweed,  goldenrod, 
etc. ;  by  emanations  from  animals,  especially  horses  and  cats ;  by  sugges- 
tion, as  in  nervous  coryza;  and  by  changes  in  reaction,  as  when  hyper- 
acidity of  the  gastric  juice  causes  the  mucous  membrane  of  the  nose  to 
swell  and  discharge  a  watery  secretion. 

Persons  who  are  susceptible  to  pollen  represent  instances  of  local 
anaphylaxis  of  the  respiratory  mucosa.  The  particular  pollen  responsible 
in  any  individual  case  may  be  determined  by  placing  a  drop  of  a  watery 
extract  upon  a  scratch  on  the  skin.  A  positive  reaction  manifests  itself 
in  five  or  ten  minutes  as  an  elevation  with  a  hyperemic  border  and  itch- 
ing. Certain  foods,  especially  eggs,  give  rise  to  respiratory  difficulty, 
asthmatic  in  nature. 

Other  Practical  Relations  of  Anaphylaxis. — Other  conditions  which 
have  been  explained  in  whole  or  part  on  the  theory  of  anaphylaxis  are 
puerperal  eclampsia,  sympathetic  ophthalmia,  the  onset  of  labor,  the 
crisis  in  pneumonia,  the  spasmophilic  diathesis,  the  symptoms  attendant 
on  the  rupture  of  the  cysts  in  echinococcus  disease,  etc.  The  anaphy- 
lactic reaction  is  also  used  in  diagnosis,  and  in  forensic  medicine  in  the 
identification  of  blood  stains,  and,  finally,  may  be  used  as  a  scientific 
instrument  for  the  detection  of  minute  amounts  of  protein. 


ANAPHYLAXIS  469 


BEFERENCES 

Many  of  the  statements  contained  in  this  chapter  have  been  taken  from 
Emery's  splendid  book  upon  "Immunity  and  Specific  Therapy,"  which  is 
recommended  to  the  reader  who  desires  a  more  extended  review  upon  the 
subject.  Kolle  and  Wassermann's  "Handbuch  der  Pathogenen  Mikroorgan- 
ismen"  has  also  been  consulted,  as  well  as  Kraus  and  Levaditi's  "Handbuch 
der  Technik  und  Methodik  der  Immunitatsforschung."  These  volumes  also 
contain  selected  bibliographies. 

The  current  literature  upon  immunity  will  be  found  in  the  Zeitschrift 
fiir  ImmunUdtsforschungen. 

For  those  who  desire  to  dip  deeper  into  the  subject  the  original  reference 
to  many  of  the  fundamental  studies  will  be  found  in  "Collected  Studies  on 
Immunity"  by  Ehrlich,  translated  by  Bolduan;  "Studies  on  Immunity"  by 
Bordet,  translated  by  Gay;  "Studies  in  Immunization"  by  Wright;  "L'lm- 
munite  dans  les  Maladies  Infectieuses"  by  Metchnikoflf,  translated  by 
Binnie ;  and  Eicketts,  H.  T. :  "Infection,  Immunity  and  Serum  Therapy 
in  Relation  to  the  Infectious  Diseases  Which  Attack  Man,"   Chicago,  1906. 


CHAPTER   II 
HEREDITY  AITD  EUGENICS 

Heredity  may  be  defined  as  the  genetic  relation  between  successive 
generations.  It  is  a  condition  of  all  organic  evolution.  Castle  defines 
heredity  as  organic  resemblance  based  on  descent. 

It  is  now  perfectly  evident  that  heredity  is  one  of  the  fundamental 
factors  in  preventive  medicine — and  of  first  importance  in  sociology. 
It  is  well  known  to  students  of  biology  that  education  and  environ- 
ment have  but  a  limited  power  to  influence  imperfect  human  proto- 
plasm. 

One  of  the  best  protections  we  have  against  diseases  of  body  and 
mind  is  that  which  is  inherited  from  our  forebears.  The  whole  prob- 
lem of  improving  the  human  stock,  not  only  from  the  medical  view, 
but  from  the  broader  sociological  standpoint,  is  based  upon  the  breed- 
ing of  the  fit  and  elimination  of  the  unfit.  The  science  of  eugenics 
(normal  genesis),  therefore,  assumes  especial  importance  in  preventive 
medicine.  The  physician,  as  well  as  the  sanitarian,  stands  impotent 
before  many  deplorable  conditions  both  in  the  individual  and  in  so- 
ciety at  large,  which  are  inherited  from  our  ancestors  and  are,  there- 
fore, incurable — but  largely  preventable.  We  are  interested  in  educat- 
ing the  present  generation  to  the  facts  of  eugenics  so  that  future  gen- 
erations may  have  that  best  of  all  birthrights — good  human  protoplasm. 

The  discoveries  of  Mendel  have  made  it  quite  clear  how  certain  char- 
acters are  inherited,  why  certain  characters  skip  a  generation  and  re- 
appear in  the  grandchildren,  and  why  it  is  that  certain  defects  are 
carried  from  generation  to  generation  through  many  centuries.^  The 
defects  transmitted  hereditarily  are  not  all  of  equal  practical  impor- 
tance. Thus,  it  makes  comparatively  little  difference  to  the  individual 
if  he  has  a  supernumerary  spleen,  an  extra  finger,  or  an  unusual  arrange- 
ment of  the  lobes  of  the  liver.  The  defects  which  are  of  especial  im- 
portance both  to  the  individual  and  to  succeeding  generations  are  the 
defects  of  the  nervous  system.  These  comprise  the  class  known  as 
defectives.  A  slight  defect  in  the  structure  of  the  brain  which  would 
be  unnoticed  in  the  lung,  bone,  or  musculature  may  render  the  individual 
vicious  instead  of  useful.     The  principal  factors  which  are  believed  to 

*  Mendel's  work  has  not  only  made  it  possible  for  us  to  predict  AA'ith  pre- 
cision whether  good  or  bad  traits  Avill  or  will  not  appear  in  the  future  offspring, 
but  also  to  foretell  with  mathematical  precision  in  what  proportion  certain  char- 
acters will  appear  and  reappear. 

470 


HEEEDITY    AND    EUGENICS  471 

start  a  line  of  defectives  are  inbreeding,  syphilis,  and  alcohol ;  also  nerv- 
ous or  physical  diseases,  mental  or  nervous  exhaustion,  and  excesses  and 
poisons  of  all  kinds.^ 

The  defective  individual  is  very  easily  recognized  when  the  condi- 
tion is  well  marked.  The  mental  abnormality  is  usually  accompanied 
by  prominent  physical  defects  known  as  the  stigmata  of  degeneration 
(Lombroso  and  Weismann).  The  typical  degenerate  is  of  poor  bodily 
development;  the  brain  is  smaller  than  normal,  with  convolutions  less 
abundant,  and  less  fully  formed.  He  has  a  degraded  physiognomy,  lacks 
capacity  for  sustained  attention  or  for  prolonged  thought,  is  cunning 
rather  than  intelligent,  deficient  in  moral  sense — in  all  points  resembling 
the  stigmata  of  the  lower,  less  developed  races  of  our  species.  The  whole 
gives  the  impression  of  a  reversion  to  a  lower  type.  An  unfortunate  side 
to  this  problem  is  that  degenerates  and  defectives  generally  are  not  only 
irresponsible  morally,  but  are  very  prolific.  They  lack  self-control  and 
have  abnormal  sexual  appetites.  Defectives  beget  defectives,  and  thus 
insanity,  nervous  diseases,  moral  and  physical  degeneracy  are  propa- 
gated. 

Feeble-minded — Idiots,  Imbeciles  and  Morons. — Feeble-minded  chil- 
dren are  now  commonly  divided  into  three  groups:  (1)  idiots,  which 
comprise  those  whose  mentality  does  not  advance  beyond  normal  children 
of  two  years;  (2)  imbeciles,,  those  whose  minds  remain  at  about  the 
fourth-year  period,  and  (3)  morons  or  fools,  those  whose  mental  con- 
dition does  not  get  farther  than  about  the  twelve-year  age.  All  grades 
of  mental  inferiority  between  the  moron  and  the  normal  occur.  Of 
these  three  groups  the  moron  is  perhaps  the  most  important  from  every 
standpoint,  for  this  is  the  group  of  defectives  that  propagates  itself, 
and  the  crop  is  large.  The  male  morons  grow  up  into  ne'er-do- 
wells  and  fill  our  hospitals  and  asylums.  The  female  morons  also 
grow  up  into  irresponsible  women  who  replenish  the  ranks  of  the  pros- 
titutes. 

The  Eoyal  Commission  of  England  reports  that  in  that  country  the 
feeble-minded  are  increasing  at  twice  the  rate  of  the  general  population. 
Butler  of  Indiana  states  that  f  eeble-mindedness  produces  more  pauperism, 
degeneracy,  and  crime  than  any  other  source ;  that  it  touches  every  form 
of  charitable  activity;  that  it  is  felt  in  every  part  of  the  state,  and 
effects,  in  some  way,  all  the  people,  and  that  its  cost  is  beyond  com- 
prehension. The  Committee  of  Visitors  of  the  State  Charities  of 
New  York  reported  that  there  are  in  that  state  32,000  feeble-minded 
persons  (191J:).  Of  these,  4,900  are  provided  for  in  institutions  espe- 
cially designed  for  their  care,  and  4,500  in  other  institutions,  leaving  at 

*The  real  cause  or  method  of  origin  of  some  defective  characters  that  are 
transmitted  hereditarily  is  no  better  understood  than  the  origin  of  "sports"  or 
mutations. 


473  HEEEDITY   AND    EUGENICS 

large  22,600.  It  has  been  estimated  that  of  the  32,000  feeble-minded, 
10,000  are  girls  and  women  of  childbearing  age,  1,750  of  whom  are 
cared  for  in  institutions  designed  for  the  care  of  such  persons,  and  1,G25 
are  confined  in  reformatories,  prisons,  and  almshouses,  leaving  about 
7,000  at  large  in  the  community.  Goddard  estimates  that  in  the  way 
of  spreading  disease,  immorality,  and  increasing  the  stock  of  the  feeble- 
minded, a  girl  or  a  woman  of  this  class,  of  childbearing  age,  is  three 
times  as  great  a  menace  to  the  community  as  is  a  feeble-minded  boy  or 
man. 

Prevention  of  Propagation  of  Defectives,. — Four  methods  have  been 
proposed  to  prevent  the  propagation  of  defectives:  (1)  education;  (2) 
legislation;  (3)  segregation;  (4)  surgery. 

Education. — Education  directed  toward  the  defective  is  a  failure, 
for  he  is  incapable  of  profiting  by  the  lessons.  The  education  of  the 
better  class  of  the  community  is  indirectly  helpful  in  calling  attention 
to  the  situation  as  being  largely  preventable,  and  to  the  necessity  and 
means  for  controlling  it. 

Eestkictive  Legislation. — Eestrictive  legislation  is  a  praiseworthy 
effort,  but  has  signally  failed  as  a  preventive  measure,  for  the  evident 
reason  that  it  only  adds  illegitimacy  to  degeneracy,  and  thus  the  chil- 
dren enter  on  life's  battle  doubly  handicapped.  Minnesota  has  a  law 
providing  that  within  the  bounds  of  the  state  no  marriage  shall  be 
permitted,  either  party  to  which  is  epileptic,  imbecile,  feeble-minded, 
or  afflicted  with  insanity,  unless  the  woman  be  over  forty-five.  Michigan, 
Delaware,  Connecticut,  Indiana,  New  Jersey,  and  North  Dakota  have 
also  passed  laws  for  the  purpose  of  preventing  marriage  among  de- 
fectives-. 

Segregation. — Segregation  would  be  an  ideal  and  humane  method 
of  isolating  those  who  are  incapable  of  having  normal  offspring.  The 
segregation  of  all  degenerates  and  defectives  would  be  an  enormous 
and  impractical  task.  Further,  the  great  difficulty  is  to  detect  the  un- 
fit individual  who  starts  a  strain  of  defectives  and  degenerates.  It  is 
evidently  a  hopeless  task  to  know  where  to  draw  the  line  between  the 
fit  and  the  unfit,  so  that  for  the  present  we  must  be  satisfied  to  enforce 
restrictive  measures  upon  only  those  who  are  evident  and  well-marked 
examples.  Insane  asylums,  homes  for  epileptics,  reformatory  schools, 
as  well  as  special  hospitals  and  institutions  for  advanced  cases  must  not  be 
regarded  as  preventive  measures  in  the  true  sense,  for  such  segregation 
provides  care  and  comfort  as  a  terminal  measure;  that  is,  it  is  usually 
a  last  resort.  Frequently  defectives  propagate  their  kind  before  and 
sometimes  after  they  are  interned  in  such  institutions.  Preference, 
nevertheless,  should  be  given  to  women  of  child-bearing  age  in  institu- 
tional care. 

Although  segregation  of  all  persons  with  higher  types  of  mental 


HEREDITY    AND    EUGENICS  473 

defect  is  never  likely  to  be  accomplished,  there  is  hope  of  devising  a 
plan  of  registration  and  guardianship  in  the  community  which  will  pro- 
tect a  great  many  and  prevent  their  marriage.^ 

Surgery. — Surgery  has  been  proposed  as  a  means  of  controlling 
the  propagation  of  defectives.  This  is  done  either  by  severing  the 
vas  deferens  or  the  Fallopian  tube.  At  the  Indiana  Eeformatory  Dr. 
Sharp  carries  out  the  law  ^  of  that  state  providing  for  the  sterilization 
of  defectives.  The  operation  of  vasectomy  consists  of  litigation  and  re- 
section of  a  small  portion  of  the  vas  deferens.  The  operation  is  very 
simple  and  easy  to  perform.  It  may  be  done  without  an  anesthetic, 
either  local  or  general.  As  performed  by  Dr.  Sharp  it  requires  about 
three  minutes,  and  the  subject  returns  to  his  work  immediately,  suf- 
fering no  inconvenience  and  in  no  way  hampered  in  his  pursuit  of  life, 
liberty,  and  happiness,  but  is  effectively  sterilized.  In  456  cases  Dr. 
Sharp  has  had  no  unfavorable  symptoms.  The  operation  is  performed 
as  follows :  After  cleansing  the  scrotum  with  soap  and  water,  fol- 
lowed by  alcohol,  the  spermatic  cord  is  grasped  between  the  thumb  and 
index  finger  of  the  left  hand.  The  vas  deferens  is  detected,  firmly 
held  and  fixed  with  a  pair  of  bullet  forceps.  It  is  then  exposed  by  a 
small  incision  and  drawn  through  the  scrotum  wound  by  means  of  a 
tenaculum.  It  is  stripped  of  all  membranes  and  the  accompanying  ar- 
tery, ligated  above  and  severed,  care  being  taken  to  cut  away  any  por- 
tion of  the  vas  deferens  that  may  have  been  damaged  in  the  manipula- 
tion. This  is  done  in  order  that  the  end  next  to  the  testicle  may  not 
become  closed.  It  is  very  important  that  the  testicular  end  shall  re- 
main open,  in  order  that  the  secretion  of  the  testicle  may  be  emptied 

*  Fernard,  "What  is  Practicable  in  the  Way  of  Prevention  of  Mental  Defect," 
a  pamphlet  distributed  by  the  National  Committee  for  Mental  Hygiene,  1915. 
Also,  Salmon,  "Outlines  of  a  State  Policy  for  Dealing  with  Mental  Deficiency," 
Medical  Record,  April  17,   1915. 

*The  Indiana  law  reads  as  follows: 

Whereas,  Heredity  plays  a  most  important  part  in  the  transmission  of 
crime,  idiocy,  and  imbecility; 

Therefore,  Be  it  enacted  by  the  General  Assembly  of  the  State  of  Indiana, 
That  on  and  after  the  passage  of  this  act  it  shall  be  compulsory  for  each  and 
every  institution  in  the  State,  entrusted  with  the  care  of  confirmed  criminals, 
idiots,  rapists,  and  imbeciles,  to  appoint  upon  its  staff,  in  addition  to  the  regular 
institutional  physician,  two  (2)  skilled  surgeons  of  recognized  ability,  whose 
duty  it  shall  be,  in  conjunction  with  the  chief  physician  of  the  institution,  to 
examine  the  mental  and  physical  condition  of  such  inmates  as  are  recommended 
by  the  institutional  physician  and  board  of  managers.  If,  in  the  judgment  of 
this  committee  of  experts  and  the  board  of  managers,  procreation  is  inadvisable 
and  there  is  no  probability  of  improvement  of  the  mental  and  physical  condition 
of  the  inmate,  it  shall  be  lawful  for  the  surgeons  to  perform  such  operation  for 
the  prevention  of  procreation  as  shall  be  decided  safest  and  most  effective.  But 
this  operation  shall  not  be  performed  except  in  cases  that  have  been  pronounced 
unimprovable.  .  .  . 

Eleven  other  states  provide  for  the  sterilization  of  either  criminals  or  the 
feeble-minded,  viz. :  California,  Connecticut,  Iowa,  Kansas,  Michigan,  Nevada, 
North  Dakota,  New  York,  New  Jersey,  Washington,  and  Wisconsin.  The  con- 
stitutionality of  the  law  has  been  appealed  to  the  Supreme  Court  in  Iowa.  Bull, 
of  the  Univ.  of  Wisconsin,  No.  82,  1  May,   1914. 


474  HEEEDITY    AND    EUGENICS 

around  the  vessels  of  the  pampiniform  plexus  and  there  he  absorbed, 
for  it  is  through  this  process  that  the  body  receives  the  tonic  effect  of 
the  internal  secretion.  Further,  if  the  testicular  end  of  the  vas  defer- 
ens is  closed,  there  is  likely  to  be  cystic  degeneration  of  the  testicle. 
The  retraction  of  the  muscle  closes  the  skin  wound  and  no  stitch,  col- 
lodion, or  adhesive  plaster  is  needed.  There  is  no  diminution  of  the 
sexual  power  or  pleasure.  The  discharge  at  the  orgasm  is  but  slightly 
decreased. 

The  operation  in  the  female  is  more  difficult,  but  if  carefully  done 
is  no  more  hazardous.  The  Fallopian  tubes  are  reached  through  a 
median  incision  and  ligated  near  the  uterus  and  severed  beyond  the 
ligature. 

Opinions  vary  greatly  concerning  the  proper  use  of  sterilizing  crim- 
inals, insane,  degenerates,  and  defectives  generally.  There  is  no  doubt 
concerning  its  effectiveness. 

Sterilization  is  a  measure  which  contains  great  potential  possibili- 
ties for  abuse  and  injustice.  It  probably  will  never  receive  general 
acceptance  on  account  of  the  difficulty  of  determining  upon  whom  the 
operation  shall  be  done.  Even  in  perfectly  clear  cases,  such  as  the  in- 
sane, the  epileptic,  or  the  high  grade  degenerate,  the  harm  has  often 
been  done  before  the  operation  is  decided  upon. 

Statistics  of  Defectives. — The  large  number  of  defectives  and  unfit 
in  our  country  may  be  gleaned  from  the  following  figures  showing  the 
number  of  inmates  in  state  institutions  in  1913.^ 

In  institutions  for — 

Feebleminded 28,805* 

Insane 205,198  ** 

Criminalistic  (including  delinquent  and  wayward)    84,328 

Epileptic 7,313  * 

Inebriate    463 

Tuberculous    .  5,995 

Blind  and  deaf 11,991 

Deformed    456 

Dependent   24,089 

Total    368,638 

*  As  of  January  1,  1916. 
**As  of  June  30,  1914. 

The  last  census  report  for  the  United  States  gives  data  relative  to 
the  dependents  and  defectives  in  institutions;  the  number  not  in  in- 

*  These  figures  were  compiled  by  the  Bureau  of  the  Census,  The  Eugenics 
Record  Office,  and  the  National  Committee  for  Mental  Hygiene. 


HEEEDITY    AND    EUGENICS  475 

stitutions  can  only  be  guessed  at.     Keliicott  gives  the  following  ap- 
proximate numbers  in  our  country  to-day: 

Insane  and  feeble-minded,  at  least 200,000 

Blind 100,000 

Deaf  and  dumb 100,000 

Paupers  in  institutions , 80,000 

Prisoners 100,000 

Juvenile  delinquents  in  institutions 23,000 

The  number  of  persons  cared  for  in  hospitals,  dispensaries,  "homes" 
of  various  kinds  in  the  year  190-1  was  in  excess  of  two  million.  All  these 
are  not  defectives,  but  many  suffer  from  preventable  disabilities. 

We  have  to  support  about  half  a  million  insane,  feeble-minded,  epi- 
leptic, blind,  and  deaf;  80,000  prisoners,  and  100,000  paupers,  at  a  cost 
of  $100,000,000  per  year.  A  new  plague  affecting  4  per  cent,  of  the 
population  and  costing  this  vast  treasure  would  instantly  attract  uni- 
versal attention.  One-sixth  of  the  total  appropriations  of  the  State  of 
Massachusetts  is  for  the  maintenance  of  insane  and  feeble-minded  in 
institutions.  We  have  become  so  used  to  crime,  disease,  and  degener- 
acy that  we  take  them  as  necessary  evils.  "That  many  of  them  were  so 
in  the  world's  ignorance  is  granted ;  that  they  must  remain  so  is  denied." 

Statistical  studies  seem  to  indicate  a  rapid  (at  least  an  unneces- 
sary) increase  of  the  unfit,  defective,  insane,  criminal,  and,  on  the 
other  hand,  a  slow  increase,  or  even  a  decrease  (?),  of  the  fit,  normal, 
or  gifted  stocks.  It  is  plain  to  the  student  of  eugenics  how  such  con- 
ditions account  for  the  rise  and  fall  of  nations. 

The  United  States  census  of  1880  reported  40,942  insane  in  hos- 
pitals and  51,017  not  in  hospitals;  a  total  of  91,959  known  insane.  In 
1903  it  was  estimated  that  there  was  a  total  of  180,000  in  the  United 
States.  Thus,  the  ratio  of  known  insane  in  the  total  population  was 
225  per  100,000  in  1903,  as  compared  with  183  per  100,000  in  1880. 
These  figures  must  not  be  taken  as  an  index  of  the  increase  of  insanity 
in  the  population  at  large — for  institutional  care  has  been  growing 
much  more  popular  during  the  past  decade,  especially  since  more  hu- 
mane methods  have  been  adopted.  Further,  the  classification  of  insan- 
ity now  includes  many-  cases  that  were  formerly  little  noticed.^  This  sub- 
ject is  fully  discussed  in  Chapter  VI. 

^  A  special  census  of  the  insane  confined  in  institutions  was  taken  by  the 
Bureau  of  the  Census  in  1910,  and  it  was  found  that  187,454  patients  were  con- 
fined in  hospitals  for  the  insane  in  the  continental  United  States. 

While  the  population  of  the  United  States  increased  about  11  per  cent,  in 
the  interval  between  1904  and  1910,  the  population  in  insane  asylums  increased 
about  25  per  cent.  The  number  of  insane  in  asylums  per  100,000  population 
increased  from  186.2  in  1904  to  203.8  in  1910.  The  number  of  persons  annually 
committed  to  hospitals  for  the  insane  per  100,000  population  increased  from  61.5 


476  HEEEDITY    AND    EUGENICS 

The  comparatively  large  and  increasing  numbers  of  defectives  and 
weaklings  among  the  civilized  races  compared  with  wild  animals  may 
be  accounted  for  by  the  fact  that  atavism  and  reversion  are  more  fre- 
quently met  with  in  artificially  cultivated  strains,  such  as  civilized 
man;  and  the  further  fact  that  our  charitable  and  philanthropic  efforts 
foster  and  even  favor  the  unfit. 

Degenerate  Families. — A  careful  study  has  been  made  of  the  records 
of  several  families  in  which  the  mating  of  unfit  individuals  has  begotten 
a  swarm  of  unfit  descendants. 

One  of  the  best  known  families  of  this  type  is  the  so-called  Jukes 
family  of  New  York  State  investigated  by  Dugdale.  This  family  is 
traced  from  the  five  daughters  of  a  lazy  and  irresponsible  fisherman 
born  in  1720.  In  five  generations  the  descendants  of  Jukes  numbered 
about  1^200  persons,  including  nearly  200  who  married  into  it.  The 
histories  of  540  of  these  are  well-known,  and  about  500  more  are  partly 
known.  Some  300  died  in  infancy.  Of  the  remaining  900,  310  were 
professional  paupers  living  in  almshouses  (a  total  of  2,300  years)  ;  440 
were  physically  wrecked  by  their  own  diseased  wickedness;  more  than 
half  of  the  women  were  prostitutes;  130  were  convicted  criminals;  60 
were  habitual  thieves;  7  were  murderers.  Not  one  had  even  a  common 
school  education;  only  20  learned  a  trade,  and  10  of  these  learned  it  in 
State's  prison.  The  descendants  of  Jukes  in  five  generations  have  cost 
New  York  State  over  one  million  and  a  quarter  dollars,  and  the  cost  is 
still  going  on. 

Probably  the  most  complete  family  history  of  this  kind  ever  worked 
out  is  that  of  the  "Familie  Zero,"  a  Swiss  family  whose  pedigree  has  been 
studied  by  Jorger.  In  the  seventeenth  century  this  family  divided  into 
three  lines.  Two  of  these  have  ever  since  remained  valued  and  highly 
respected  families,  while  the  third  has  descended  to  the  depths.  This 
third  line  was  established  by  a  man  who  was  himself  the  result  of  two  gen- 
erations of  intermarriage,  the  second  tainted  with  insanity.  He  was  of  a 
roving  disposition,  and  in  the  Yalla  Eontana  found  an  Italian  vagrant 
wife  of  vicious  character.     Their  son  inherited  fully  the  parental  traits 

in  1904  to  65.9  in  1910.  If  these  ratios  are  accepted  as  representing  insanity 
rates,  it  would  appear  tliat  tlie  number  of  persons  becoming  insane,  in  a  com- 
munity comprising  100,000  persons,  was  greater  by  4.4  in  1910  than  it  was  in 
1904.  It  must  be  remembered,  however,  that  these  figures  include  only  tlie  insane 
who  are  committed  to  liospitals.  As  to  the  number  of  cases  of  insanity  not 
resulting  in  commitments  to  hospitals  the  census  has  no  data.  It  is  entirely 
possible  that  the  increase  in  the  number  of  commitments  per  100,000  population 
is  not  due  to  any  considerable  degree  to  an  increased  prevalence  of  insanity,  but 
simply  to  the  extension  of  tliis  method  of  caring  for  the  insane.  It  is  a  change 
which  might  result  from  an  increase  in  the  number  of  institutions  of  tliis  class 
and  from  the  increasing  disposition  on  the  part  of  the  public  to  resort  to  such 
institutions.  In  this  connection  it  may  be  noted  that  the  number  of  institutions 
for  the  insane  reported  by  the  census  increased  from  328  in  1904  to  372  in 
1910,  an  increase  of  about  13  per  cent.  The  average  number  of  inmates  per 
institution  increased  from  458  in  1904  to  504  in  1910. 


HEEEDITY   AND    EUGENICS 


477 


and  himself  married  a  member  of  a  German  vagabond  family — Marcus. 
This  marriage  sealed  the  fate  of  their  hundreds  of  descendants.  The 
pair  had  seven  children,  all  characterized  by  vagabondage,  thievery, 
drunkenness,  mental  and  physical 
defects,  and  immorality  (Kellicott). 
How  much  of  this  is  due  to  hered- 
ity and  how  much  to  environment 
will  be  discussed  presently. 

Another  interesting  example  of 
the  same  type  has  been  described 
by  Poellmann.  This  family  was 
established  by  two  daughters  of  a 
woman  drunkard  who  in  five  or  six 
generations  produced,  all  told,  834 
descendants.  The  histories  of  709 
of  these  are  known.  Of  the  709, 
107  were  of  illegitimate  birth,  64 
were  inmates  of  almshouses,  163 
were  professional  beggars,  164  were 
prostitutes,  and  17  procurers,  76 
had  served  sentences  in  prison,  ag-  ^ 
gregating  116  years,  7  were  con- 
demned for  murder.  ^^ 

Dr.  Henry  H.  Goddard  ^  has  in-  ^^ 
vestigated  and  compiled  the  results 
of  his  work  on  the  heredity  of  a  most 
remarkable  family,  the  Kallikak 
family.  During  the  Eevolutionary 
days,  the  first  Martin  Kallikak  (the 
name  is  fictitious),  descended  from  a 
long  line  of  good  English  ancestry, 
took  advantage  of  a  feeble-minded 
girl.  The  result  of  their  indulgence 
was  a  feeble-minded  son.  This  son 
married  a  normal  woman.  They  in 
turn  produced  five  feeble-minded  and 
two  normal  children.  Practically  all 
of  the  descendants  of  these  defec- 
tives have  been  traced,  as  well  as 
those  of  the  two  normals. 

Erom  both  normal  and  defective  descendants  of  this  union  came  a 
long  line  of  defective  stock.     There  were  480  in  all.     Of  these  thirty- 

*"The   Kallikak    Family,   a   Study   in   the  Heredity   of   Feeble-miadedneaa," 
New  York,  Macmillan  Company,   1912. 


s 


478  HEEEDITY    AND    EUGENICS 

six  were  illegitimate,  thirty-three  sexually  immoral,  twenty-four  con- 
firmed alcoholics,  and  three  epileptics.  Eighty-two  died  in  infancy, 
three  were  criminal,  eight  kept  houses  of  ill  fame,  and  143  were  dis- 
tinctly feeble-minded.  Only  forty-six  were  found  who  were  apparently 
normal.  The  rest  are  unknown  or  doubtful.  But  the  scion  of  the  good 
family  who  started  this  long  line  of  delinquent  and  defective  progeny 
is  also  responsible  for  a  strain  of  an  entirely  different  character.  After 
the  Eevolutionary  War  was  over,  he  married  a  Quaker  girl  of  good 
ancestry  and  settled  down  to  live  a  respectable  life  after  the  traditions 
of  his  forefathers.  From  this  legal  union  with  a  normal  woman  there 
have  been  496  descendants.  All  of  these  except  two  have  been  of  normal 
mentality.  The  exceptions  were  cases  of  insanity,  presumably  inherited 
through  marriage  with  an  outside  strain  in  which  there  was  a  consti- 
tutional psychopathic  tendency.  In  all  the  496  there  is  not  an  instance 
of  feeble-mind edness.  The  offspring  descended  from  this  side  of  the 
house  have  universally  occupied  positions  in  the  upper  walks  of  life. 
They  have  never  been  criminals  or  ne'er-do-wells.  On  the  other  hand, 
there  has  not  been  a  single  instance  of  exceptional  ability  among  the 
descendants  of  the  first  Martin  Kallikak  and  the  feeble-minded  girl. 
Most  of  these  descendants  have  failed  to  rise  above  the  dead  level  of 
mediocrity;  indeed,  most  of  them  have  fallen  far  below  even  this  mini- 
mum standard. 

The  fact  that  the  descendants  of  both  the  normal  and  the  feeble- 
minded mother  have  been  traced  and  studied  in  every  conceivable  en- 
vironment, and  that  the  respective  strains  have  always  been  true  to 
type,  tends  to  confirm  the  belief  that  heredity  has  been  the  determining 
factor  in  the  formation  of  their  respective  characters.  In  the  cities 
the  descendants  of  the  legal  marriage  with  the  normal  woman  are 
physicians,  lawyers,  and  prominent  business  men,  while  the  descendants 
of  the  feeble-minded  mother  are  almost  invariably  found  in  the  slums. 
In  the  rural  districts  the  descendants  of  the  normal  mother  and  her  con- 
sort are  wealthy  and  infiuential  farmers,  while  the  others  never  rise 
above  the  rank  of  farm  laborers  and  shiftless  men  and  women,  who  are 
unable  to  subsist  without  the  aid  of  charity.  Many  representatives  of 
the  defective  branch  are  inmates  of  almshouses,  while  there  are  no 
paupers  at  all  among  the  normal  descendants. 

In  many  ways  this  study  of  Goddard's  far  outweighs  in  importance 
the  famous  comparison  by  Dr.  Winship  of  the  Jukes  and  Edwards  fam- 
ilies. In  that  case  the  simple  fact  was  demonstrated  that  a  good  family 
like  that  of  the  illustrious  Jonathan  Edwards  had  given  rise  to  innu- 
merable examples  of  the  highest  intellectual  and  moral  worth,  whereas 
the  criminal  Jukes  for  seven  generations  contributed  nothing  to  the 
common  good  and  cost  the  state  of  New  York  large  sums  of  money. 
But  the  Jukes  family  and  the  Edwards  family  had  no  ancestor  in 


EUGENICS  479 

common.  Their  environment  was  totally  different  and  they  lived  in 
entirely  separate  communities.  Although  from  sociologic  and  economic 
points  of  view  the  history  of  the  Jnkes  family  and  its  comparison  with 
that  of  the  family  of  Jonathan  Edwards  has  great  value,  it  is  of  but 
scant  scientific  importance  as  compared  with  that  of  the  Kallikak  family, 
for  here  a  natural  object-lesson  in  eugenics  shows  unmistakably  the 
manner  in  which  after-coming  generations  from  a  given  mating  receive 
the  characteristics  of  the  dominant  strain,  which  in  the  elder  (illegiti- 
mate) Kallikak  line  was  the  inferior  strain,  with  only  a  debased  and 
enfeebled  heritage  to  hand  on.^ 

In  contrast  to  these  we  have  the  descendants  of  the  families  of 
Wedgwood,  Darwin,  and  Galton,  the  Edwards  family  and  the  Ward 
family.  These  three  noted  families  contained  a  large  number  of  states- 
men, jurists,  professors,  physicians,  officers  in  the  army  and  navy,  prom- 
inent authors  and  writers,  and  occasionally  men  and  women  of  genius. 
They  show  a  long  line  of  usefulness  in  every  department  of  social  prog- 
ress, and  not  one  of  them  ever  has  been  convicted  of  a  crime. 

How  much  of  this  is  due  to  heredity  and  how  much  to  environment 
are  debatable  questions.  Students  of  biology  are  convinced  that  heredity 
plays  the  major  role  in  the  lives  of  the  individuals  in  the  above-men- 
tioned families.  In  how  far  such  extreme  instances  as  those  given  above 
represent  the  rule  or  exceptions  will  require  much  additional  data  and 
long  years  of  study  to  determine. 


EUGENICS 

The  science  of  eugenics  has  been  defined  as  "the  science  of  being 
well  born."  According  to  Gallon,  '^''eugenics  is  the  study  of  the  agen- 
cies under  social  control  that  may  improve  or  impair  the  racial  quali- 
ties of  future  generations  either  physically  or  mentally." 

The  aim  of  eugenics  is  to  increase  the  number  of  best  specimens 
in  each  class;  that  done,  leave  them  to  work  out  their  common  civiliza- 
tion in  their  own  way.  It  also  aims  to  leave  a  good  heritage  to  the 
next  generation  and  to  repress  the  propagation  of  the  vicious  and  de- 
fective classes. 

The  success  of  eugenics  depends  almost  entirely  upon  our  knowl- 
edge of  heredity  and  sociology.  Therefore,  the  fundamental  principles 
of  heredity  should  be  familiar  to  all  students  of  preventive  medicine. 

The  present  movement  started  in  1865  when  Francis  Galton  showed 
that  mental  qualities  are  inherited,  just  as  are  physical  qualities,  and 
pointed  out  that  this  opened  a  way  to  an  improvement  of  the  race  in 
all  respects.     The  student  should  read  Galton's  work  on  "Hereditary 

^J.  A.  M.  A.,  Oct.  26,  1912,  LIX,  17,  p.  1545. 


480 


HEEEDITY    AND    EUGENICS 


Genius,"  published  in  18G9,  when  he  again  emphasized  definitely  the 
possibility  and  desirability  of  improving  the  natural  qualities  of  the 
human  race.  The  word  "eugenics"  was  coined  in  1883  in  his  "In- 
quiries Into  the  Human  Faculty." 

There  is  no  doubt  concerning  the  desirability  of  breeding  better 
human  stock,  but  how  this  may  be  accomplished  practically  is  a  diffi- 
cult question.  The  program  of  the  eugenist  is  perplexing  and  compli- 
cated. To  follow  the  theoretical  extremists  would  require  a  social  revo- 
lution— a  change  from  the  present  method  of  haphazard  mating.     The 

h/eOCWOOD  DARWfN  C ALTON 


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A  shows  a  man  of  scientific  ability  ;  ^  shows  a  man  orscicntiiic  ability,  who  is  alH»  • 
Fellow  of  the  Royal  Society  ;  (s)  shows  five  other  children,  and  so  on. 

Fig.  61. — History  (Condensed  and  Incomplete)  op  Three  Markedly  Able  Families 
(After  Whentham)  (Kellicott). 

threshold  of  the  subject  has  scarcely  been  passed,  and  we  must  bear 
in  mind  that  some  of  the  striking  men  of  genius  from  whom  the  world 
has  greatly  profited  have  been  individuals  whom  the  student  of  genetics 
would  regard  as  degenerates  or  defectives.  Eugenics  does  not  mean 
free  love,  nor  does  the  eugenist  recommend  Burbanking  the  human  race 
to  produce  great  physical  strength,  beauty,  endurance,  mental  or  moral 
power.  One  point  only  in  the  program  is  perfectly  clear,  and  that  is  that 
a  check  should  be  placed  upon  the  propagation  of  the  crop  of  defectives 
by  means  already  pointed  out. 

The  known  facts  of  heredity  and  the  study  of  eugenics  make  us 
examine  more  critically  some  of  the  directions  which  preventive  medi- 
cine, including  philanthropy  and  social  uplift,  has  taken.  We  must  now 
ask  ourselves  the  question  whether  it  would  not  be  better  for  the  future 


PEINCIPLES    OF    HEEEDITY  481 

generations  if  we  helped  the  fit  rather  than  the  weakling  and  the  unfit. 
These  are  problems  raised  by  Galtoii,  who  questions  whether  some  of  our 
philanthropic  efl'orts  are  well  balanced  and  well  directed. 

According  to  the  teachings  of  genetics,  all  men  are  not  created  free 
and  equal;  but  bound  by  their  protoplasmic  make-up  and  unequal  in 
their  powers  and  responsibilities. 

It  is  evidently  now  of  great  importance  to  collect  a  large  number 
of  pedigrees,  in  which  the  data  shall  be  stated  with  scientific  exactness 
and  in  minute  detail.  Such  a  mass  of  facts  may  then  be  studied  in  the 
light  of  science  in  order  to  determine  in  how  far  the  laws  of  heredity 
apply  to  human  characters.  This  is  being  done  by  the  Eugenics  Eecord 
Office  at  Cold  Springs  Harbor,  New  York,  under  the  patronage  of  the 
Carnegie  Institution. 

Specifically,  the  Eecord  Office  seeks  pedigrees  of  families  in  which 
one  or  more  of  the  following  traits  appear:  short  stature,  tallness,  cor- 
pulency; special  talents  in  music,  art,  literature,  mechanics,  invention, 
and  mathematics;  rheumatism,  multiple  sclerosis,  hereditary  ataxy, 
Meniere's  disease,  chorea  of  all  forms,  eye  defects  of  all  forms,  otosclero- 
sis, peculiarities  of  hair,  skin,  and  nails  (especially  red  hair),  albinism, 
harelip  and  cleft  palate,  peculiarities  of  the  teeth,  cancer,  Thomsen's 
disease,  hemophilia,  exophthalmic  goiter,  diabetes,  alkaptonuria,  gout, 
peculiarities  of  the  hands  and  feet  and  of  other  parts  of  the  skeleton. 

In  brief,  then,  the  aim  of  eugenics  is  through  heredity  to  give  the 
individual  the  greatest  of  all  birthrights,  viz.,  good  human  protoplasm, 
and  to  eliminate,  as  far  as  may  be  possible,  bad  human  protoplasm. 


PRINCIPLES  OF  HEREDITY 

For  a  clearer  understanding  of  the  hereditary  transmission  of  dis- 
ease, malformations,  and  defects  it  is  necessary  to  have  an  understand- 
ing of  the  principal  views  upon  organic  evolution  and  the  theories  of 
heredity.  The  student  of  preventive  medicine  should  especially  have 
a  clear  comprehension  of  Mendel's  work,  which  has  thrown  a  flood  of 
light  upon  the  problems  before  us.  Mendel  has  opened  new  vistas  in 
biology,  which  have  a  practical  bearing  upon  public  health  work.  It 
is  evidently  impossible  in  a  short  space  to  do  justice  to  such  large  sub- 
jects as  evolution  and  heredity,  and  the  student  is,  therefore,  referred 
to  the  authorities  given  at  the  end  of  this  chapter,  which  will  repay 
careful  study. 

Variation. — It  has  been  a  matter  of  common  observation  that  like 
tends  to  beget  like  rather  than  "like  begets  like,"  for  there  is  a  ten- 
dency toward  new  departures. 

Two  distinct  sorts  of  divergences  may  appear  among  the  members 

ir 


4:82  HEREDITY    AND    EUGENICS 

of  a  single  family.  The  first  is  known  as  variation;  the  second  as 
mutation. 

By  variation  we  understand  those  slight  dilTcrcnccs  which  invariably 
distinguish  all  the  members  of  every  family.  They  consist  of  individ- 
ual differences  which  affect  every  part  and  every  character.  Such  dif- 
ferences are  also  known  as  fluctuating,  normal,  or  continuous  variations 
to  distinguish  them  from  abnormal,  definite,  or  discontinuous  varia- 
tions, which  are  more  properly  termed  mutations.  As  examples  of 
variation  in  man  we  may  cite  the  variations  in  size  or  stature,  color  of 
skin  and  eyes,  curliness  of  hair,  configuration  of  features,  etc. 

Darwin  lays  particular  emphasis  upon  the  importance  of  variation 
in  his  views  of  organic  evolution. 

Darwin's  Theory. — The  Sukvival  of  the  Fittest. — Darwin's 
views  ^  of  heredity  form  the  basis  of  his  theory  of  organic  evolution.  Two 
separate  factors  are  primarily  concerned :  ( 1 )  the  fact  of  fluctuating 
variation,  that  is,  that  no  two  members  of  the  same  family  ever  resemble 
one  another  exactly;  and  (2)  the  occurrence  of  a  struggle  for  existence 
between  organisms,  owing  to  the  geometric  rate  of  increase  of  living 
things.  From  these  two  facts  it  follows  that,  when  a  change  of  environ- 
ment takes  place,  certain  members  of  an  existing  species  will  be  some- 
what better  adapted  than  others  to  withstand  the  new  conditions,  and 
the  former  will  tend  to  survive  to  the  exclusion  of  the  latter.  Darwin 
assumes  that  during  long  series  of  generations  this  process  will  result  in 
a  steady  change  in  the  character  of  the  species  in  the  direction  of 
better  adaptation  to  the  new  conditions.  In  other  words^  Darwin 
considers  that  an  accumulation  of  a  series  of  small  changes  due  to  the 
influence  of  environment  are  transmitted  hereditarily  through  natural 
selection. 

The  remarkable  effects  produced  in  the  case  of  domestic  animals  and 
plants  by  the  action  of  artificial  selection  greatly  influenced  Darwin's 
views  upon  the  selective  influences  which  exist  in  nature.  Darwin  be- 
lieved in  the  hereditary  transmission  of  acquired  characters  and  re- 
garded organic  evolution  as  proceeding  by  a  slow,  gradual,  or  continuous 
process.  There  can  be  no  doubt  that  natural  and  sexual  selection 
have  a  great  influence,  but  whether  sufficient  to  originate  new  species 
or  even  new  specific  characters  is  a  question.  Now  that  the  transmis- 
sion of  acquired  characters  is  denied  by  students  of  heredity,  and  the 
fact  that  DeVries  has  actually  observed  new  species  arise  suddenly, 
Darwin's  theory  of  organic  evolution  and  the  origin  of  species  is  receiv- 
ing critical  examination. 

Darwin  firmly  believed  that  the  characters  of  organisms  can  be 
modified  by  selection,  and  he  made  this  the  foundation  stone  of  his 
theory  of  evolution.    The  brilliancy  of  the  mutation  theory  of  DeVries, 

^  Darwin :     "The  Origin  of  Species,"  etc. 


PEINCIPLES    OF    HEEEDITY  483 

coupled  with  his  great  service  to  biology  in  rediscovering  the  Mendelian 
laws,  has  somewhat  dazzled  our  eyes.  Castle  believes,  after  ten  years 
of  continuous  work  in  selection,  that  much  may  be  accomplished  by 
this  means  quite  apart  from  the  process  of  mutation,  and  considers 
that  the  work  of  DeVries  himself  argues  strongly  in  favor  of  this  idea, 
although  his  interpretation  of  it  is  adverse  to  selection.  From  the  evi- 
dence at  hand  we  must  conclude  that  Darwin  was  right  in  assigning 
great  importance  to  selection  in  evolution,  that  progress  results  not 
merely  from  sorting  out  particular  combinations  by  large  and  striking 
unit  characters,  but  also  from  the  selection  of  slight  differences  in  the 
potentiality  of  gametes  representing  the  same  unit  character  combina- 
tions. 

Mutation. — Mutations  comprise  definite  differences,  usually  of  con- 
siderable magnitude — differences  that  indicate  specific  characters  or  the 
beginning  of  new  species.  Such  differences  are  also  known  as  abnormal, 
definite,  or  discontinuous  variations,  but  more  properly  they  are  termed 
mutations,  sometimes  "sports."  Mutations  may  be  either  useful  or 
harmful.  They  arise  "spontaneously"  and  are  transmitted  in  accordance 
with  Mendel's  law.  As  examples  of  mutations  in  man  we  may  cite  albin- 
ism, polydactylism,  brachydactylism,  etc. 

DeVries,  Bateson,  and  the  "mutationists"  are  convinced  that  muta- 
tion is  a  much  more  important  factor  in  the  origin  of  species  than  varia- 
tion, as  understood  by  Darwin.  In  the  light  of  Mendel's  work  mutations 
appear  to  be  unit  characters  which  arise  "spontaneously" — in  some  in- 
stances they  represent  recessive  characters  that  have  remained  dormant 
for  many  generations. 

DeVries — Discontinuous  Evolution. — The  observations  of  DeVries 
upon  the  evening  primrose  (Oenothera  lamarckiana)  convinced  him  that 
species  may  arise  suddenly,  that  evolution  is  discontinuous  and  goes  by 
leaps  and  bounds  rather  than  by  the  slow  or  continuous  process  of  or- 
ganic evolution  described  by  Darwin. 

Mutation  is  the  term  applied  by  DeVries  to  express  the  process  of 
origination  of  a  new  species  or  a  new  specific  character,  when  this  takes 
place  by  the  discontinuous  method  at  a  single  step.  DeVries  believes 
that  this  is  the  most  important,  if  not  the  sole,  method  by  which  new 
species  or  specific  characters  arise.  To  those  who  are  convinced  that 
acquired  characters  are  not  inherited  the  explanations  of  Lamarck  and 
Darwin  have  always  been  incomplete.  Darwin  insisted  that  nature  does 
not  make  jumps  and  that  new  species  arise  slowly  through  the  action 
of  natural  selection  on  minute  variations — a  gradual  or  continuous  evo- 
lution.^ From  his  experiments  DeVries  .concludes  that  when  selection 
is  really  efficient  the  full  possible  effects  of  this  process  are  exhausted  in 

^Darwin,  however,  recognized  the  facts  of  mutations  or  "sports"  as  he 
called  them  and  dwelt  upon  their  importance. 


484 


HEREDITY    AND    EUGENICS 


quite  a  small  number  of  generations,  and  that  then  the  only  further 
effect  of  selection  is  to  keep  up  the  standard  already  arrived  at.  DeVries 
actually  observed  quite  a  number  of  new  types  of  plants  which  arose 
suddenly  and  naturally.  When  they  made  their  appearance  the  majority 
of  the  new  types  came  true  to  seed.  With  regard  to  the  causes  of  muta- 
tion little  is  known,  unless  we  assume  that  they  represent  unit  characters 
which  have  long  remained  recessive. 

Weismann's  Views. — Weismann's  ^  views  are  based  largely  upon  his 
assumption  that  the  germ  plasm  is  distinct  from 
the  body  and  that  acquired  characters  are  not 
inherited.  The  parent  is  composed  biologically 
of  somatic  or  body  cells  which  are  mortal,  and 
reproduction  cells  or  germ  plasm  which  is  dis- 
tinct, continuous,  immortal.  The  germ  cells 
undergo  the  least  modification  from  their  orig- 
inal condition.  Indeed,  Weismann  believes  that 
there  is  no  reason  for  supposing  that  they  have 
undergone  any  modification  at  all.  From  this 
point  of  view  we  may  consider  the  nature  of  a 
given  series  of  animals  as  being  determined  only 
by  the  particular  series  of  cells  which  consti- 
tute the  direct  ancestry  of  the  germ  cells  in 
each  individual.  The  cells  which  make  up  the 
bodily  structure  may  be  regarded  as  the  result 
of  so  many  offshoots  which  come  to  an  end  at 
the  death  of  the  organism  and  have  no  progeny 
of  their  own. 

The  minute  study  of  the  germ  cells  taken  in 
connection  with  modern  experimental  work  on 
the  methods  by  which  inheritance  takes  place 
shows  a  strong  tendency  to  confirm  Weismann's 
views,  so  far  as  the  inheritance  of  distinct  and 
definite  characters  is  concerned. 

Wilson  ^  has  expressed  Weismann's  theory  as 
follows :  It  is  a  reversal  of  the  true  point  of 
view  to  regard  inheritance  as  taking  place  from  the  body  of  the  parent 
to  that  of  the  child.  The  child  inherits  from  the  parent  germ  cell,  not 
from  the  parent  body,  and  the  germ  cell  owes  its  characters  not  to  the 
body  which  bears  it,  but  to  its  descent  from  a  preexisting  germ  cell  of 
the  same  kind.  Thus,  the  body  is,  as  it  were,  an  offshoot  from  the  germ 
cell.    As  far  as  inheritance  is  concerned,  the  body  is  merely  the  carrier 


Fig.  62. — Wilson's  The. 
ORT  OF  Inheritance 
Modified  by  Lock  (G, 
germ  cells;  S,  somatic 
cells) . 


*  Weismann,    A.:       "Essays    upon    Heredity,"    1889,    and    "The    Evolution 
Theory,"  1906. 

*  Wilson:     "The  Cell  in  Development  and  Inheritance,"  p.  13. 


PRINCIPLES    OF   HEREDITY 


485 


of  the  germ  cells  which  are  held  in  trust  for  coming  generations.     Fig. 
63  illustrates  Wilson's  theory  of  inheritance  as  modified  by  Lock. 

Mendel's  Law. — We  are  indebted  to  Mendel  ^  for  one  of  the  most 
important  observations  of  biology — the  most  important,  in  fact,  with 
reference  to  heredity.  The  essential  factors  of  Mendel's  discovery  are : 
(1)  unit  characters,  (2)  dominance,  (3)  segregation.  By  a  unit  charac- 
ter is  understood  any  characteristic  of  an  individual  that  is  transmitted 

A  Schematic  Representation  of  Mendel's  Law 

D  R . . . .  P* — great-grandparental  generation 

D  R . . . .  P^* — grandparental  generation. 


D 
\ 


\       / 


R. 
/ 


D(R) 


.  P^ — parental  generation. 
F^ — first  filial  (hybrid)  generation. 


2DD 
Pure  dominants 


DD        IDD 


DD 


2D(R) 
Impure  dominants 


2D(R) 


IRR  F3— second  filial 

Pure  recessives       (inbred)  genera- 
tion. 


IRR        RR 


DD     IDD    2D(R)    IRR     RR         RR 


F' — third  genera- 
tion. 


F^ — fourth  gener- 
ation. 


D  and  R  represent  complementary  unit  characters,  D  the  dominant  character, 
and  R  the  recessive  character.  D(R)  represents  a  dominant  with  the  recessive 
character  unexpressed  but  potentially  present.  DD  means  pure  dominants,  and 
RR  pure  recessives. 


from  parent  to  offspring  through  successive  generations  and  which  con- 
forms to  the  following :  When  parents  with  complementary  unit  charac- 
ters unite,  it  is  found  that  one  character  predominates  over  the  other. 
This  is  known  as  dominance.  It  has  further  been  found  that  the  unit 
characters  contributed  by  the  respective  parents  do  not,  as  a  rule,  blend, 

*Gregor  Johann  Mendel  was  born  July  22,  1822,  at  Heizendorf  in  Austrian 
Silesia.  In  184.3  he  entered  the  Augustine  Convent  at  Altbrunn  as  a  novice,  and 
was  ordained  priest  in  1847.  Mendel  was  a  teacher  of  natural  science  in  the 
Brunn  Realschule  from  1853  to  1868,  when  he  was  appointed  abbot  of  his 
monastery. 

Mendel  published  only  the  results  of  his  work  upon  hybridization  with  peas 
and  a  few  of  his  experiments  with  Hieracium.  The  original  paper  on  "Hybridi- 
zation" was  published  in  the  Verh.  NaUirf.  Ter.  in  Brunn,  Abthandlungen  IV, 
1865,  which  appeared  in  1866;  the  paper  on  "Hieracium"  appeared  in  the  same 
journal,  VIII,  1869.  The  student  is  advised  to  read  "Mendel's  Principles  of 
Heredity"  by  W.  Bateson,  1909,  in  which  he  will  find  a  translation  of  these  two 
important  papers.  A  clear  exposition  is  also  given  by  R.  C.  Punnett  in  his  book 
entitled  "Mendelism"    (1911). 


486  HEKEDITY    AND    EUGENICS 

but  remain  separate  or  distinct.  This  is  known  as  segregation.  The 
principles  of  segregation  and  dominanco  have  been  found  to  apply  to  the 
inheritance  of  many  characters  in  animals  and  plants.  Tt  should  l)e  care- 
fully borne  in  mind  that  the  unit  characters  themselves  arc  not  trans- 
mitted as  such  in  the  germ  cells.  Just  Avhat  is  transmitted  is  not  defi- 
nitely known.  It  is  quite  sure  that  the  only  thing  that  is  inherited  in  the 
germ  cells  is  something  which  determines  the  development  of  the  unit 
character.     This  something  is  called  a  determiner. 

The  essence  of  this  great  discovery  was  published  by  Mendel  in  a 
short  paper  in  1866.  By  some  extraordinary  chance  Mendel's  observa- 
tions were  entirely  lost  sight  of  until  the  same  facts  were  independently 
rediscovered  in  1899  by  DeVries,  working  in  Holland,  by  Correns  in  Ger- 
many, and  by  Tschermak  in  Austria. 

Mendel's  law  may  best  be  understood  from  a  concrete  illustration. 
One  of  the  simplest  cases  is  that  of  the  heredity  of  color  in  the  Andalu- 
sian  fowl,  which  has  been  so  clearly  described  by  Bateson. 

There  are  two  established  color  varieties  of  this  fowl :  one  with  a  great 
deal  of  black  and  one  that  is  white  with  some  black  markings  or  splashes. 
For  convenience  we  may  refer  to  these  as  the  black  and  white  varieties 
respectively.  Each  of  these  breeds  true  by  itself.  Black  mated  with 
black  produce  none  but  black  offspring.  White  mated  with  white  pro- 
duce none  but  wdiite  offspring.  Crossing  black  and  white,  however,  re- 
sults in  the  production  of  fowls  with  a  sort  of  grayish  color  called 
"blue"  by  the  fancier,  though  in  reality  it  is  a  fine  mixture  of  black 
and  white.  If  we  continue  to  breed  succeeding  generations  from  these 
blue  hybrid  fowls  we  get  three  different  colored  forms.  Some  will  be 
blue,  like  the  parents,  some  black,  like  one  grandparent,  some  white, 
like  the  other  grandparent.  Further,  these  different  colors  appear  in 
certain  definite  proportions  among  the  three  classes  of  descendants.  Of 
the  total  number  of  the  immediate  offspring  of  the  hybrid  blues,  ap- 
proximately one-half  will  be  blue,  like  the  parents,  approximately  one- 
fourth  black,  and  one-fourth  white,  like  each  of  the  grandparents.  Thus, 
black  bred  together  produce  only  blacks;  the  M^hite  similarly  produce  only 
whites;  the  blues,  on  the  other  hand,  when  bred  together  produce  a 
progeny  sorting  into  three  classes,  and  in  the  same  proportion  as  that 
produced  by  the  blues  of  the  original  hybrid  generation.  The  fact  that 
the  black  grandchildren  and  the  white  grandchildren  respectively  breed 
true  is  a  very  important  fact.  In  this  illustration  no  race  of  the  hybrid 
blue  character  can  be  established,  for  the  blues  always  produce  blacks 
and  whites  as  well  as  blues  (see  diagram). 

Another  instance  which  illustrates  the  phenomenon  of  dominant  and 
recessive  characters  as  well  as  segregation  is  here  given.  If  black  and 
white  varieties  of  guinea-pigs  are  crossed  the  offspring  are  all  black,  like 
one  parent ;  that  is,  when  black  and  white  characters  are  brought  together 


PEINCIPLES    OF    HEREDITY 


487 


in  the  guinea-pig,  these  do  not  appear  to  blend  into  gray  or  '"blue/'  as 
in  the  case  of  the  Andalusian  fowl,  but  one  character  alone  appears. 
The  black  seems  to  cover  up  or  wipe  out  the  white.  The  black  color  is, 
therefore,  said  to  be  dominant  and  the  white  recessive.    The  white  charac- 


W'O  t?t7 


Fig.  63. — Diagram  Showing  the  Course  of  Color  Heredity  in  the  Andalusian 
Fowl,  in  Which  One  Color  Does  Not  Completely  Dominate  Another.  P, 
parental  generation.  The  offspring  of  this  cross  constitute  Fi,  the  first  fiUal  or  hybrid 
generation.  Fo,  the  second  filial  generation.  Bottom  row,  third  filial  generation. 
(KeUicott.) 

ter,  however,  has  not  disappeared,  for  when  the  black  offspring  are 
crossed  together  the  progeny  falls  into  two  groups:  some  black  and  some 
white.  Three-fourths  of  the  progeny  are  black;  that  is,  they  resemble 
the  hybrid  form  and  at  the  same  time  one  of  the  grandparents,  while 


CO 


F, 


r. 


CD  CDCD 


Fig.  64. — Diagram  Showing  the  Course  of  Color  Heredity  in  the  Guinea-pig,  in 
Which  One  Color  (Black)  Completely  Dominates  Another  (White).  Refer- 
ence letters  as  in  Fig.  63.     (Kellicott.) 

the  remaining  fourth  resemble  the  other  white  grandparent.  Some  of 
these  blacks  will  breed  true  and  are,  therefore,  known  as  homozygotes. 
Some  of  the  blacks  contain  a  mixture  of  the  black  and  white  characters 
and  are,  therefore,  known  as  heterozygotes.    The  hereditary  transmission 


488  HEREDITY    AND    EUGENICS 

of  the  color  character  in  these  two  illustrations  through  the  germ  cell  is 
shown  in  the  accompanying  diagram. 

Unit  characters  may  either  be  positive  or  negative;  that  is,  they  may 
be  due  to  the  presence  or  absence  of  "something''  in  the  germ  cell  or 
sperm  cell.  This  something,  known  as  a  determiner,  is  a  force,  a  molec- 
ular structure  or  an  enzyme  (?)  in  the  nuclear  matter  of  the  germ 
plasm.  Thus,  the  determiner  in  the  case  of  pigment  is  not  the  pig- 
ment itself,  but  something  that  activates  pigment  production.  These 
determiners  are  transmitted  in  the  germ  plasm  and  are  the  only  things 
that  are  truly  transmitted.  The  determiner  may  be  either  in  the  ovum 
or  the  sperm. 

An  hereditable  character  may  be  due  to  the  presence  or  absence  of 
a  determiner  in  the  germ  plasm  of  both  parents.  When  a  character  is 
due  to  the  presence  of  a  determiner  it  is  called  positive,  when  due  to 
the  absence  of  a  determiner,  negative.  Thus,  a  brown  eye  depends  on 
a  determiner  that  produces  the  brown-colored  pigment,  while  the  blue 
eye  depends  upon  the  absence  of  such  a  determiner.  It  is  not  always 
easy  to  anticipate  whether  a  given  character  is  positive  or  negative. 
For  instance,  long  hair  in  Angora  cats,  sheep,  or  guinea-pigs  is  ap- 
parently not  due  to  a  factor  added  to  short  hair,  but  rather  to  an 
absence  of  a  determiner  that  stops  growth  in  short-haired  animals. 

One  of  the  most  important  conclusions  from  Mendel's  observations 
is  that  the  different  inherited  traits  act  independently;  that  is,  they 
do  not  blend.  In  other  words,  the  definitely  hereditable  characters 
act  as  independent  units  that  are  without  any  apparent  relation  to  other 
peculiarities  of  the  individual  concerned.  Furthermore,  these  units  do 
not  interfere  with  each  other.  It  follows  that  all  the  unit  characters 
of  an  individual  are  to  be  regarded  as  mutually  independent  assemblages. 
This  is  the  doctrine  of  unit  characters.  According  to  this  doctrine,  each 
individual  is  of  dual  origin,  paternal  and  maternal,  and  each  individual 
is  made  up  of  a  mosaic  of  inherited  characters,  some  of  which  may  be 
dominant,  others  recessive.  The  idea  of  unit  characters  capable  of 
being  inherited  independently  of  one  another  is  one  of  the  most  important 
conceptions  which  has  been  added  to  our  knowledge  of  heredity.  We 
now  know  from  the  phenomenon  of  segregation  what  constitutes  purity 
in  a  strain  of  animals  or  plants;  that  is,  purity  does  not  depend  upon 
the  length  of  time  during  which  a  race  has  exhibited  a  constant  character, 
for  a  strain  of  absolute  purity  may  arise  from  the  second  generation  of 
a  cross.  Mendel's  law  has  not  only  explained  many  facts  in  heredity, 
but  also  has  important  practical  bearing  in  the  improvement  of  the  breeds 
of  cultivated  plants  and  domestic  animals. 

Atavism  and  Reversion. — Atavism  (from  atavus,  a  grandfather)  is 
the  inheritance  of  properties  not  manifest  in  either  parent,  but  pres- 
ent in  the  grandfather  or  some  relatively  remote  ancestor.     Mendel's 


PRINCIPLES    OF    HEREDITY  489 

observations  upon  recessive  characters  now  make  plain  some  of  the  phe- 
nomena known  as  atavism.  According  to  Castle,  atavism  or  reversion 
to  an  ancestral  condition  can  be  completely  explained  by  the  Mendelian 
principles.  It  is  nothing  more  or  less  than  the  reassertion  of  recessive 
unit  characters  that  have  long  been  overshadowed  by  dominant  charac- 
ters. It  seems  that  recessive  characters  may  not  be  lost,  no  matter  how 
long  they  remain  latent  or  dormant. 

The  term  "atavism"  is  sometimes  employed  to  mean  any  reversion- 
ary condition,  whether  favorable  or  unfavorable,  while  the  term  "re- 
version" means  a  return  in  the  offspring  to  a  lower  type,  usually  of 
some  remote  ancestor.  The  degenerations  which  run  in  families  may 
be  instances  either  of  atavism  or  reversion,  or  mutation. 

Darwin's  classical  experiment  illustrating  reversion  consisted  in  cross- 
ing a  barbed  fan-tail  female  pigeon  with  a  barbed  spot  male  and  produc- 
ing offspring  hardly  distinguishable  from  the  wild  Shetland  species  of 
blue-rock  pigeon  (Colomha  livia).  This  is  a  case  of  reversion,  in  which 
an  artificially  bred  and  highly  specialized  race  quickly  recovered  charac- 
ters which  had  been  lost  during  many  generations.  A  foal  is  sometimes 
born  with  a  few  stripes  on  its  forelegs,  as  if  reminding  us  of  striped 
wild  horses.  Highly  cultivated  and  specialized  flowers  and  vegetables 
have  a  tendency  to  revert,  and  sometimes  produce  forms  hardly  distin- 
guishable from  their  wild  progenitors. 

Reversion  is  due  to  the  reassertion  of  latent  ancestral  characters.  It 
is  an  impelling  hereditary  force  which  must  be  taken  into  account.  True 
reversion  may  arise  in  pure  bred  races,  but  is  much  more  frequent  as  the 
result  of  hybridization. 

The  facts  of  reversion  and  atavism  are  of  peculiar  interest  to  man, 
for  the  reason  that  the  human  species  has,  through  unconscious  selec- 
tion and  conscious  effort,  improved  the  race  to  its  present  point  of 
superiority.  Whether  civilized  man  to-day  is  superior  to  ancient  races 
may  be  doubted,  but  the  fact  is  plain  that  civilization  is  breeding  an 
artificial  and  highly  specialized  strain  that  shows  artificial  departures 
from  primitive  stock. 

It  is  well  known  that  the  high  bred  and  "fancy"  races  of  the  do- 
mesticated animals  show  a  marked  tendency  to  reversion  or  deteriora- 
tion of  type.  Likewise,  the  human  race  shows  the  same  tendency  to 
revert  to  types  resembling  its  forebears.  The  present  level  attained  by 
the  more  highly  civilized  races  can  only  be  maintained  by  a  continua- 
tion of  that  struggle  for  improvement,  progress,  and  desire  for  per- 
fection which  is  an  inborn  characteristic  and  an  essential  element  of 
progress.  Owing  to  the  artificial  position  to  which  the  human  race 
has  brought  itself,  it  becomes  necessary  to  continue  the  struggle — to 
stand  still  means  rapid  deterioration.  Some  of  the  stigmata  of  degen- 
eration and  hereditary  defects  may  be  accounted  for  by  this  natural 


490  HEREDITY    AND    EUGENICS 

tendency  on  the  part  of  an  artificially  nurtured  standard  to  slip  back- 
ward. 

Galton's  Law  of  Filial  Regression. — Filial  regression  has  nothing  to 
do  with  reversion.  The  law  of  filial  regression  concretely  stated  is  that 
offspring  are  not  likely  to  differ  from  mediocrity  in  a  given  direction 
so  widely  as  "their  parents  do  in  the  same  direction.  There  is  a  contin- 
ual tendency  to  sustain  a  specific  average  or  a  stock  average. 

Let  us  take  a  simple  instance  from  Professor  Karl  Pearson's  "Gram- 
mar of  Science."  Suppose  a  group  of  fathers  with  a  stature  of  73  in.; 
the  mean  height  of  their  sons  is  70.8  in. — a  regression  toward  the  mean 
height  of  the  general  population.  On  the  other  hand,  fathers  with  a 
mean  height  of  66  in.  give  a  group  of  sons  of  mean  height  68.3  in. — 
again  nearer  the  mean  height  of  the  general  population.  The  "regres- 
sion" works  both  ways — there  is  a  leveling  up  as  well  as  a  leveling  down. 
"The  father  with  a  great  excess  of  the  character  contributes  sons  with 
an  excess,  but  a  less  excess  of  it;  the  father  with  a  great  defect  of  the 
character  contributes  sons  with  a  defect,  but  less  of  it"  (Thompson). 

THE   CELL  IN   HEREDITY 

Each  parent  (male  and  female)  is  composed  biologically  of  somatic 
or  body  cells,  which  are  mortal,  and  germ  plasm  which  is  distinct,  con- 
tinuous, immortal.  The  development  and  embryology  of  the  germ  and 
sperm  cells  are  of  particular  interest  to  the  student  of  heredity. 

The  view  has  gained  ground  and  general  acceptance  that  the  nucleus 
is  the  chief  or  exclusive  bearer  of  the  hereditable  characters;  that  is, 
the  female  nuclear  material  transmits  the  characters  of  the  mother  and 
her  forebears  and  the  male  nucleus  those  of  the  father  and  his  forebears 
to  the  offspring. 

Cells  divide  and  multiply  in  two  ways:  (1)  by  direct  division  or 
amitosis,  and  (2)  by  indirect  division  or  mitosis.  Direct  division  oc- 
curs more  frequently  than  is  usually  suspected.  The  process  appears 
to  be  a  very  simple  one;  the  nucleus  divides  without  any  preliminary 
arrangement  of  its  structure,  the  cytoplasm  is  constricted,  and  presently 
we  have  two  cells  in  place  of  one.  Indirect  division  or  mitosis  appears 
to  be  the  natural  mode  of  cell  development.  The  chromatin,  which  is 
the  deeply  staining  matter  in  the  nucleus,  rearranges  itself  from  its 
"resting"  stage.  After  a  complicated  process  the  nuclear  matter  forms 
itself  into  a  long  cylindrical  thread  known  as  the  linene  thread.  This 
then  divides  into  links  or  chromosomes.^  The  chromosomes  are  of  spe- 
cial interest,  for  they  are  believed  to  carry  the  "determiners." 

^For  a  full  understanding  of  cell  division  the  student  is  referred  to  one  of 
the  standard  text-hooks  upon  Cytology,  or  Minot's  "Embryology";  also,  to  E.  B. 
Wilson's  "The  Cell  in  Development  and  Inheritance,"  2d  lEd.,   1900. 


THE    CELL    IN    HEEEDITY  491 

In  mitotic  division  each  chromosome  is  divided  in  half  longitu- 
dinally, as  a  stick  might  be  split  up  the  middle,  and  after  a.  very  com- 
plex process  the  halves  of  each  split  chromosome  migrate  to  opposite 
poles.  Then  each  centrosome  attracts  a  group  of  chromosomes  con- 
sisting of  just  one-half  of  the  original  chromatin  material.  Each  group 
then,  in  orderly  fashion,  rounds  itself  into  a  new  nucleus,  and  the  body 
of  the  cell  (the  cytoplasm)  constricts  across  the  equatorial  plane,  and 
t'vvo  cells  are  formed. 

Every  species  of  plant  or  animal  has  a  fixed  and  characteristic 
number  of  chromosomes  which  regularly  recurs  in  the  division  of  all 
of  its  cells  and  in  all  forms  arising  by  sexual  reproduction  the  number 
is  even.  Thus,  in  some  of  the  sharks  the  number  of  chromosomes  is 
36,  in  certain  gastrapodes  it  is  32 ;  in  the  mouse  and  salamander,  the 
trout,  the  lily,  24;  in  the  worm  Saggita,  18;  in  the  ox  and  guinea-pig, 
16 ;  in  man  the  number  was  formerly  stated  as  16,  now  24.  In  crus- 
taceans the  number  of  chromosomes  may  be  as  high  as  168.  In  a  few 
insects  the  females  have  in  their  body  cells  one  chromosome  in  addition 
to  the  number  possessed  by  the  males.  This  has  been  interpreted  as 
bearing  upon  the  determination  of  sex. 

Van  Beneden  in  1885  discovered  the  important  fact  that  the  nu- 
cleus of  the  ovum  and  the  nucleus  of  the  spermatozoon  which  unite 
in  fertilization  contain  each  one-half  of  the  number  of  chromosomes 
characteristic  of  the  body  cells. 

As  both  the  germ  and  sperm  cells  contain  only  half  the  number  of 
chromosomes,  a  reduction  must  take  place  in  the  history  of  these  cells; 
in  fact,  alike  in  the  history  of  the  germ  cell  and  in  the  history  of  the 
sperm  cell,  there  is  a  parallel  reduction  in  the  number  of  chromosomes 
to  one-half.  This  reduction  appears  to  be  a  preparation  of  the  repro- 
duction cells  for  their  subsequent  union,  and  a  means  by  which  the 
number  of  chromosomes  is  held  constant  in  the  species. 

In  sexual  reproduction  each  centrosome  attracts  a  group  of  chromo- 
somes, half  of  which  are  of  paternal  origin  and  half  of  maternal  origin. 
This  is  interpreted  as  meaning  that  the  paternal  and  maternal  chromo- 
somes that  unite  to  form  the  new  zygote  probably  carry  the  hereditable 
characters. 

The  gist  and  meaning  of  the  whole  process  to  the  student  of  hered- 
ity is  the  precisely  equal  partition  of  the  maternal  and  paternal  con- 
tributions, so  that  each  of  the  zygote  cells  that  is  to  form  a  new  individ- 
ual has  a  nucleus  half  from  the  mother  and  half  from  the  father. 

Although  the  ovum  is  much  larger  than  the  spermatozoon,  each  con- 
tributes equally  so  far  as  the  amount  of  nuclear  matter  is  concerned; 
the  new  individual  is  dual  in  its  origin,  and  the  offspring  is  a  double 
creature  and  retain^  its  duality  to  its  dying  day,  and  transmits  it  to 
succeeding  generations. 


493  HEEEDITY    AND    EUGENICS 

Professor  E.  B.  Wilson  states  the  generally  accepted  opinion  some- 
what as  follows:  As  the  ovum  is  much  larger  it  is  believed  to  furnish 
the  initial  capital — including,  it  may  be,  a  legacy  of  food  yolk — for  the 
early  development  of  the  embryo.  From  both  parents  alike  comes  the 
inherited  organization  which  has  its  seat  (according  to  most  biologists) 
in  the  readily  stainable  chromatin  rods  of  the  nuclei.  From  the  father 
comes  a  little  body,  the  centrosome,  which  organizes  the  machinery  of 
division  by  which  the  egg  splits  up  and  distributes  the  dual  inheritance 
equally  between  the  daughter  cells. 

The  ovum  may  be  stimulated  to  segmentation  without  the  sperm  cell 
(parthenogenesis).  When  this  happens  individuals  are  produced  similar 
to,  but  not  as  vigorous  as,  the  normal  types.  The  sperm  cell  similarly  is 
able  to  develop  without  the  nuclear  matter  of  the  egg.  In  other  words, 
the  ovum  and  the  sperm  each  contain  potential  factors  for  the  new 
individual.  As  we  have  already  seen,  in  accordance  with  Weismann's 
theory,  that  the  germ  plasm  is  independent  of  the  body  and  is  continu- 
ous; therefore,  acquired  characters  not  affecting  the  germ  plasm  are  not 
inherited  in  accordance  with  this  conception. 

Foreign  bodies  carried  along  by  either  the  germ  or  sperm  cells  are 
examples  of  congenital  transmission  and  not  instances  of  true  heredity; 
therefore,  in  the  present-day  conception  of  heredity  it  is  not  possible  for 
a  microbic  disease  to  be  transmitted  hereditarily,  even  though  the  micro- 
organism is  contained  in  either  the  germ  or  the  sperm.  Thus,  hens  may 
be  caused  to  lay  colored  eggs  by  feeding  the  hens  with  anilin  dyes.  Ana- 
phylaxis is  an  example  of  a  transmitted  property,  but  the  "substance,'^ 
whatever  it  is,  seems  to  be  carried  along  with  the  maternal  germ  cell  as 
a  foreign  body.  In  the  case  of  syphilis,  the  Treponema  pallidum  may  be 
carried  along  by  the  germ  or  sperm,  and  the  disease  is  said  to  be  trans- 
mitted hereditarily,  but,  strictly,  the  microorganism  is  carried  as  a  foreign 
body  and  not  as  a  unit  character  or  constituent  part  of  the  nuclear  matter. 


BIOMETRY 

Statistical  methods  applied  to  biology  have  been  termed  biometry 
by  Professor  Karl  Pearson.  Francis  Galton's  book  on  "Natural  In- 
heritance" is  a  pioneer  in  the  subject,  and  embodies  a  lucid  introduction 
to  the  statistical  study  of  variation  and  inheritance.  The  health  offi- 
cer must  be  familiar  with  statistical  methods  not  only  in  their  applica- 
tion to  biology,  but  as  they  relate  to  vital  statistics.  The  health  officer 
who  lacks  the  quantitative  view  or  who  fails  to  grasp  the  statistical 
values  of  the  facts  and  factors  in  preventive  medicine  works  under  a 
decided  handicap.  The  sanitarian  who  is  ignorant  of  statistical  methods 
must  necessarily  grope  in  the  dark.     Efficiency  and  economy  in  public 


BIOMETEY 


493 


health  work  depend  not  alone  upon  a  knowledge  of  the  biological  sciences, 
but  also  upon  a  correct  sense  of  proportion.  The  statistical  method  is  a 
strong  lever  which  makes  for  sane  administration,  economy  in  expendi- 
ture, efficiency  of  effort;  in  short,  successful  results. 

Statistics  deal  with  groups  rather  than  with  individuals..  It  must 
be  understood  that  the  average  of  a  group  may  represent  something 
quite  different  from  any  individual  which  the  group  contains.  Also  a 
group  may  contain  individuals  of  very  diverse  natures.  In  collecting 
statistical  material  the  data  must  be  gathered  without  any  preconceived 

A  B 


Fig.  65. — Model  to  Illustrate  the  Law  of  Probability  or  "Chance."  A,  Peas 
held  in  container  at  top  of  board.  B,  Peas  after  having  fallen  through  the  obstruc- 
tions into  the  vertical  compartments  below.  The  curve  connecting  the  tops  of  the 
columns  of  peas  is  the  normal  probability  curve. 

ideas  and  without  neglecting  any  members.  In  this  respect  statistical 
methods  differ  from  biological  methods,  which  require  careful  discrimi- 
nation of  data. 

The  quantitative  determination  of  a  character  may  be  made  by  various 
methods,  as  by  counting  or  by  measurement. 

The  statistical  method  may  be  illustrated  by  a  simple  model,  such 
as  that  suggested  by  Galton.  This  is  a  modification  of  the  familiar 
bagatelle  board  covered  with  glass  and  arranged  as  shown  in  Fig.  65. 
A  funnel-shaped  container  at  the  top  of  the  board  is  filled  with  peas 
or  similar  objects.  Below  this  is  a  regular  series  of  obstacles  symmetri- 
cally arranged,  and  at  the  bottom  of  the  board  is  a  row  of  vertical  com- 


494 


HEEEDITY    AND    EUGENICS 


partments  also  arranged  symmetrically  with  reference  to  the  chief  axis 
of  the  whole  system.  If  we  allow  the  peas  to  run  through  the  funnel 
and  fall  among  the  obstacles  into  the  compartments  below,  we  find  that 
their  distribution  will  follow  certain  laws  capable  of  precise  mathe- 
matical d-escription.  The  distribution  of  the  peas  may  be  predicted 
with  fair  accuracy.  The  middle  compartment  will  receive  the  most; 
the  compartments  next  the  middle  somewhat  fewer ;  those  further  from 
the  middle  still  fewer;  and  the  end  compartment  fewest.  If  we  connect 
the  top  of  each  column  of  peas  by  a  curved  line  we  get  a  curve  known 
as  the  "normal  frequency  curve."  A  curve  of  the  same  essential  char- 
acter would  result  from  plotting  the  dimensions  of  a  thousand  cobble- 
stones, the  deviation  from  the  bull's  eye  in  a  target-shooting  contest. 


Q  M  0 

Fig.  66. — Normal  Curve.     (Lock.) 


or  by  plotting  the  variability  of  a  biologic  character,  such  as  the  stature 
or  strength  of  men,  the  spread  of  sparrows'  wings,  the  number  of  rays 
on  scallop  shells,  or  of  ray  flowers  of  daisies. 

While  from  the  above  law  of  probability  we  know  quite  definitely 
w^hat  the  general  distribution  of  the  peas  will  be,  we  do  not  know  at 
all  the  future  position  of  any  single  pea.  Of  this  we  can  speak  only  in 
terms  of  probability.  The  chances  are  very  high  that  it  will  fall  in 
one  of  the  three  middle  compartments,  very  low  that  it  will  be  one  of 
the  extreme  compartments.  The  chances  are  equal  that  any  individual 
pea  will  fall  above  or  below  the  average  or  middle  position.  We  there- 
fore see  that  in  any  group  there  are  many  more  individuals  near  the 
average  than  there  are  in  the  classes  removed  from  the  average,- and 
the  farther  the  removal  of  a  class  from  the  average  the  smaller  the 
number  of  individuals  in  that  class;  hence,  we  have  the  important  fact 
in  statistical  methods  that  an  individual  may  belong  to  a  group  with- 
out representing  it  fairly.     In  order  to  get  a  correct  idea  of  the  whole 


BIOMETKY  495 

group  we  must  know  first  to  what  extent  deviation  in  each  direction 
occurs  above  and  below  the  group  average;  and,  second,  the  average 
amount  by  which  each  individual  of  the  group  deviates  from  this  group 
average;  that  is,  we  must  know  the  amount  of  variability  as  well  as 
the  extent  of  the  greatest  divergence  from  the  average.  Hence,  we  have 
the  following  definitions  and  corollaries : 

The  mode  of  a  normal  curve  is  the  longest  perpendicular  which  can 
be  drawn  from  the  base  line  to  meet  the  curve  itself,  M,  Fig.  &%.  The 
normal  curve  is  symmetrically  on  either  side  of  the  mode;  that  is  to 
say,  two  perpendiculars  drawn  from  the  base  to  the  curve  on  either  side 
of  the  mode  and  at  the  same  distance  from  it  will  be  equal  in  length. 

The  median  is  a  perpendicular  line  which  divides  the  area  of  the 
curve  into  two  equal  halves.  In  dealing  with  a  symmetrical  curve  the 
position  of  the  mode  is  identical  with  that  of  the  median. 

The  mean  or  average  of  all  the  values  from  which  the  curve  is  con- 
structed is  the  foot  of  the  median.  In  any  actual  case  obtained  by 
practical  methods  the  position  of  the  mode,  the  median,  and  the  mean 
will  only  be  approximately  the  same  because  such  a  curve  is  never 
perfectly  symmetrical. 

The  quartile  is  the  distance  from  the  median  to  a  perpendicular 
line  extending  from  the  base  of  the  curve  at  such  a  distance  from  the 
median  that  it  divides  the  area  inclosed  by  the  median,  the  base,  and 
half  the  curve  into  two  equal  parts.  Any  given  curve  will  have  two 
quartiles,  one  on  either  side  of  the  median.  They  are  shown  at  Q 
and  Q'.     (Fig.  Q&.) 

A  variate  is  one  of  the  separate  numerical  values  from  which  a 
curve  of  variability  can  be  constructed.  The  accuracy  of  the  statistical 
method  is  usually  proportionate  to  the  number  of  variates  out  of  which 
the  curve  is  built.  The  biometrician  usually  deals  with  some  such  num- 
ber as  1,000  variates.  The  total  number  of  variates  is  represented  by 
the  area  inclosed  by  the  curve,  and  it  will  be  seen  that  half  the  total 
number  of  variates  falls  between  the  two  quartiles  and  half  outside  of 
them. 

A  class  may  be  defined  as  a  group  of  variates  all  of  which  show  a 
particular  value  or  a  value  falling  between  certain  limits.  In  vital  statis- 
tics the  term  class  is  used  to  express  quantities  that  cannot  be  measured 
or  expressed  by  figures ;  as,  sex,  nationality,  etc. 

Groups  are  measurable  and  can  be  expressed  by  figures;  as,  age, 
height,  weight,  etc. 

The  frequency  of  a  class  is  the  number  of  variates  which  it  contains. 

The  amount  of  variation  shown  by  a  particular  group  of  variates 
is  measured  by  the  degree  of  slope  of  the  curve.  A  flat  curve  indicates 
greater  variability  and  a  steep  curve  denotes  less  variability. 

The  standard  deviation  of  a  normal  curve  is  the  measure  of  vari- 


496  HEEEDITY    AND    EUGENICS 

ability  and  is  more  often  used  than  the  qiiartilc  and  is  expressed  shortly 
as  (7  .  The  value  of  o-  is  found  by  multiplying  the  square  of  the  devi- 
ation of  each  class  from  the  mean  (or  mode)  by  the  frequency  of  the 
class,  adding  together  the  series  of  products  so  obtained,  dividing  this 
number  by  the  total  number  of  variates,  extracting  the  square  root  of 
the  result,  and  multiplying  by  the  number  of  units  in  the  class  arranged. 

The  coefficient  of  variability  is  a  purely  abstract  number  obtained 
by  dividing  the  standard  deviation  by  the  magnitude  of  the  mean  in 
any  particular  case  and  multiplying  the  result  by  100. 

The  probable  error  arises  from  the  circumstances  that  half  the  total 
number  of  variates  lies  outside  the  limits  of  the  quartile  and  half  within. 
The  probable  error  of  any  statistical  determination  is  obtained  by  find- 
ing a  pair  of  values  lying  one  above  and  one  below  the  true  value  re- 
quired. 

For  further  details  consult: 

Bowley:     "Elements  of  Statistics,"  1907,  Charles  Scribner's  Sons. 

Bowley:  "An  Elementary  Manual  of  Statistics,"  1910,  London, 
Macdonald  &  Evans. 

King:    "Elements  of  Statistical  Method,"  1912,  Macmillan  &  Co. 

Newsholme :    "Elements  of  Vital  Statistics,"  1899,  Macmillan  &  Co. 

Davenport,  Chas.  B. :  "Statistical  Methods,  with  Special  Eef  erence  to 
Biological  Variation,"  2nd  Ed.,  New  York,  1904,  John  Wiley  and  Sons. 

Elderton:  "Primer  of  Statistics,"  New  York,  1912,  The  Macmillan 
Co. 

HEREDITY    VERSUS    ENVIRONMENT 

How  much  of  our  physical  and  mental  makeup  is  due  to  heredity 
(nature)  and  how  much  to  environment  (nurture)  is  one  of  the  much- 
discussed  problems.  It  seems  evident  to  students  of  biology  that  by 
far  the  overwhelming  factor  in  our  organization  is  set  and  definitely 
fixed  at  our  birth.  Heredity  appears  to  be  the  overshadowing  influence 
of  first  and  prime  importance.  Herbert  Spencer  well  said  that  "in- 
herited constitution  must  ever  be  the  chief  factor  in  determining  char- 
acter." Environment  may  influence  the  individual,  but  apparently  has 
small  and  slow  power  of  propagating  itself  for  good;  great  and  rapid 
power  for  evil.  That  is,  the  hereditary  transmission  of  acquired  char- 
acters is  denied,  but  the  transmission  of  defects  of  organization,  such 
as  insanity,  deaf  mutism,  the  consequences  of  syphilis,  alcoholism,  and 
other  vices,  are  fully  recognized.  Atavism,  reversion,  and  mutations 
must  not  be  regarded  as  instances  of  the  hereditary  transmission  of 
acquired  characters  in  the  biological  sense.  The  tendency  of  the  artifi- 
cially bred  strains  of  the  civilized  human  races  to  revert  and  deteriorate 
has  already  been  emphasized. 


IMMUNITY    GAINED    THROUGH   INHEEITANCE       497 

Despite  the  teachings  of  biology  we  are  convinced  that  life  is  in- 
exorably conditioned  by  its  environment.  The  environment  of  today 
is  the  heredity  of  tomorrow.  Jordan  states  that  "among  the  factors 
everywhere  and  inevitably  connected  with  the  course  of  descent  of  any 
species  variation,  heredity,  selection,  and  isolation  mu.st  appear;  the  first 
two  innate,  part  of  the  definition  of  organic  life;  the  last  two  extrinsic, 
arising  from  the  necessities  of  environment,  and  not  one  of  these  can 
find  leverage  without  the  presence  of  the  others."  In  the  present  state 
of  our  knowledge,  while  we  are  convinced  that  heredity  plays  the  major 
r61e,  we  are  by  no  means  prepared  to  deny  the  influence  of  environment. 


IMMUNITY    GAINED    THROUGH    INHERITANCE 

Immunity  to  disease  is  either  natural  or  acquired.  Natural  immu- 
nity is  inherited  through  successive  generations  of  a  species  or  a  race. 
Acquired  immunity,  like  other  acquired  characters,  is  probably  not  in- 
herited as  a  "unit  character"  in  the  sense  of  Mendel.  Thus,  there  has 
been  little  variation  in  our  natural  power  to  resist  most  infections,  such 
as  tuberculosis,  yellow  fever,  plague,  smallpox,  cholera,  tetanus,  measles, 
scarlet  fever,  diphtheria,  and  so  on  through  a  long  list,  although  these 
diseases  have  doubtless  afflicted  the  human  species  through  untold  ages. 
The  fluctuating  virulence  of  some  infections  is  a  matter  of  common 
knowledge,  and  is  doubtless  due  to  many  factors.  In  a  few  well-known 
instances  a  certain  amount  of  tolerance  or  resistance  has  been  gained  and 
perhaps  transmitted  through  succeeding  generations  by  a  process  of  the 
survival  of  the  fittest.  Thus,  syphilis  is  much  less  virulent  now  than  it 
was  during  the  great  pandemic  of  the  sixteenth  century.  The  resistance 
which  the  natives  enjoy  to  malaria  in  badly  infected  quarters  of  the 
globe  is  largely  acquired  as  a  result  of  early  infections,  and  this  increased 
resistance  is  perhaps  partly  transmitted  by  a  weeding  out  of  the  very  sus- 
ceptible (see  chapter  on  Immunity). 


CHAPTEE  III 
THE  HEEEDITAEY  TEANSMISSION  OE  DISEASE 

We  are  now  prepared  to  discuss  more  in  detail  the  hereditary  trans- 
mission of  disease.  The  question  whether  disease  is  ever  transmitted 
hereditarily  or  not  rests  somewhat  upon  our  conception  of  disease;  that 
iS;,  whether  it  is  an  entity,  a  process,  or  a  "unit  character/'  The  process 
itself,  of  course,  cannot  be  transmitted,  but  the  potentiality  of  it  may 
be  involved  in  some  peculiarity  in  the  organization  of  the  germ  plasm. 
This  may  be,  and  often  is,  transmitted  through  successive  generations. 
in  the  limited  sense  in  which  the  word  'Tieredity"  is  used  in  biology 
and  in  the  limited  sense  in  which  the  word  "disease"  is  used  in  pathology, 
there  may  be  no  inherited  diseases,  but  this  appears  to  be  a  quibble  of 
words  or  a  matter  of  definitions.  While  we  are  not  familiar  with  the 
intimate  processes  concerned,  we  are  certain  that  many  abnormal  condi- 
tions of  mind  and  body  are  transmitted.  Some  of  them  follow  the  Men- 
delian  principles. 

Formerly  a  large  number  of  diseases  were  regarded  as  transmissible, 
but  the  list  has  been  revised  and  restricted  as  a  result  of  recent  studies. 
The  reappearance  of  a  diseased  condition  in  successive  generations  does 
not  prove  that  it  has  been  transmitted  or  even  that  it  is  transmissible. 
This  mistake  has  been  made  with  tuberculosis  and  other  infections. 

Lack  of  completeness  vitiates  most  of  the  statistics  bearing  on  heredity 
in  relation  to  human  diseases.  Even  in  the  case  of  clearly  inherited 
diseases  there  are  very  few  pedigrees  sufficiently  complete  for  the  study 
of  the  applicability  of  Mendelian  and  other  laws  of  heredity. 

Sometimes  the  disease  itself  is  not  transmitted,  but  a  tendency  to 
the  disease  is  transmitted.    This  will  be  discussed  again. 

Some  unit  characters  as  well  as  certain  diseases  are  transmitted 
hereditarily,  but  limited  to  one  sex;  that  is,  the  disease  or  condition 
appears  in  one  sex  only,  although  transmitted  by  the  other. 

This  remarkable  sort  of  inheritance,  known  as  sex-limited  inheritance, 
occurs  when  the  male  parent  is  characterized  by  the  absence  of  some 
character  of  which  the  determiner  is  typically  lodged  in  the  sex  (x) 
chromosome.  A  striking  feature  of  this  sort  of  heredity  is  that  the 
trait  appears  only  in  males  of  the  family,  but  is  not  transmitted  by 
them;  it  is  transmitted,  however,  through  normal  females  of  the  family. 
Examples  of  this  sort  of  heredity  occur  in  hemophilia,  color-blindness, 
also  in  multiple  sclerosis,  atrophy  of  the  optic  nerve,  myopia,  ichthyosis, 

498 


THE    HEEEDITAEY    TEANSMISSIOIsT    OF    DISEASE    499 

aud  muscular  atrophy.  The  explanation  is  the  same  in  all  cases  of 
sex-limited  heredity.  The  ahnormal  condition  is  due  to  the  absence  of 
a  determiner  from  the  male  sex  chromosome. 

The  diseases,  defects,  and  conditions  believed  to  be  transmitted 
hereditarily  are  discussed  in  the  following  pages.  Some  of  these  dis- 
eases, malformations,  and  defects  of  organization  follow  Mendel's  law. 
It  is  probable  that  other  diseases,  tendencies,  and  characters  are  trans- 
missible, but  the  subject  has  only  recently  been  placed  upon  a  scientific 
basis,  and  it  will  require  careful  and  prolonged  observation  to  estab- 
lish the  facts.  It  is  often  difficult  to  determine  whether  the  disease 
itself  or  a  tendency  to  the  disease  has  been  transmitted  in  any  particular 
case,  and,  further,  it  is  often  difficult  to  decide  whether  an  individual  has 
inherited  or  acquired  his  affliction. 

The  transmissible  defects  which  are  of  principal  concern  to  the  human 
species  are  the  defects  of  organization  of  the  central  nervous  system. 
It  is  important  to  remember  that  the  defects  of  the  nervous  system  do 
not  necessarily  propagate  just  the  same  defects  in  the  succeeding  genera- 
tions. Thus,  an  epileptic  does  not  necessarily  beget  epileptics;  epilepsy, 
insanity,  degeneracy,  color-blindness,  and  other  stigmata  may  arise  as 
the  result  of  deficiencies  of  various  kinds  in  the  forebears. 

Defects  such  as  harelip,  cleft  palate,  cervical  fistula,  spina  bifida, 
etc.,  are  not  true  instances  of  hereditary  transmission  of  specific  char- 
acters. They  rather  represent  an  inherited  deficiency  in  developmental 
vigor.  These  defects  for  the  most  part  represent  the  failure  of  parts 
to  unite  during  embryological  development;  in  other  words,  the  failure 
of  embryological  clefts  to  close  normally.  Such  deformities,  as  well  as 
clubfoot,  web  fingers,  and  other  acquired  or  congenital  deformities  or 
disfigurations,  are  not,  as  a  rule,  transmitted. 

Some  practical  problems  of  great  importance  arise  from  our  knowl- 
edge of  the  hereditary  transmission  of  disease  and  defects.  A  man  or 
woman  who  intends  marrying  is  now  more  than  justified  in  carefully 
examining  the  personal  and  medical  histories  of  the  family  of  his  or 
her  intended  mate.  It  is  not  only  possible  to  foretell  the  color  of  the 
eyes,  the  nature  of  the  hair,  and  other  Mendelian  characters  in  the 
future  offspring,  but  it  is  also  possible  to  foretell,  with  mathematical 
precision,  the  chances  of  transmitting  defects,  such  as  insanity,  epilepsy, 
degeneracy,  deaf-mutism,  color-blindness,  migraine,  and  other  nervous 
disorders,  as  well  as  hemophilia,  polydactylism,  brachydactylism,  albin- 
ism, and  other  stigmata.  In  any  doubtful  case  it  may  be  well  to  consult 
a  student  of  heredity,  for  it  is  possible  to  foretell  with  precision  in  certain 
cases  which  characters  will  and  which  will  not  be  transmitted. 

To  illustrate  the  precision  with  which  the  characters  of  offspring 
may  be  predicted  in  the  best  studied  cases,  we  need  only  refer  to  the 
color  of  the  eyes.    Two  parents  with  pure  blue  eyes  will  have  only  blue- 


600    THE    HEREDITARY    TEANSMISSION    OF    DISEASE 

eyed  offspring,  for  they  both  lack  the  brown  pigment  which  determines 
the  color  of  the  iris.  Similarly,  if  the  hair  of  parents  be  flaxen,  this  may 
be  taken  as  evidence  of  the  absence  of  a  hair-pigment-determiner  in  the 
germ  plasm,  and  the  offspring  will  have  flaxen  hair.  For  the  same  reason 
parents  with  lack  of  curliness  or  waviness  of  hair  will  have  only  straight- 
haired  children. 

In  determining  whether  transmissible  characters  are  apt  to  reappear 
in  successive  generations  or  not  we  must  know  whether  these  characters 
are  positive  or  negative,  that  is,  whether  they  are  due  to  the  presence 
or  absence  of  determiners.^ 

Inbreeding  may  be  hazardous,  for  reasons  that  are  well  understood. 
The  marriage  of  cousins  will  be  evidently  hazardous  if  the  objection- 
able hereditary  characters  are  dominant,  for  in  this  case  the  danger  is 
plain;  if  the  characters  are  recessive  the  danger  is  specially  unfortunate, 
because  of  unexpected  outcroppings  in  the  offspring.  Inbreeding  tends 
to  secure  homozygous  combinations,  and  this  brings  to  the  surface  latent 
or  hidden  recessive  characters.  Crossbreeding  brings  together  differen- 
tiated gametes  which,  reacting  on  each  other,  produce  offspring  of  greater 
vigor.  On  the  other  hand,  continued  crossbreeding  only  tends  to  hide 
inherent  defects,  not  to  exterminate  them ;  inbreeding  only  tends  to  bring 
them  to  the  surface,  not  to  create  them.  It  is  not,  therefore,  correct  to 
ascribe  to  inbreeding  by  intermarriage  the  creation  of  bad  racial  traits, 
but  only  their  manifestation.  Further,  a  racial  stock  which  maintains 
a  high  standard  of  excellence  under  inbreeding  is  certainly  one  of  great 
vigor  and  free  from  inherent  defects  (Castle). 

The  influence  of  isolation  and  the  results  of  consanguineous  marriage 
are  well  brought  out  when  we  study  certain  localities.  Thus,  consanguin- 
ity on  Martha's  Vineyard  results  in  11  per  cent,  deaf  mutes  and  a  number 
of  hermaphrodites;  in  Point  Judith,  13  per  cent,  idiocy  and  7  per  cent, 
insanity;  in  an  island  off  the  Maine  coast  the  consequence  is  "intellec- 
tual dullness" ;  in  Block  Island,  loss  of  fecundity ;  in  some  of  the  "Banks" 
off  the  coast  of  North  Carolina  suspiciousness  and  an  inability  to  pass 
beyond  the  third  or  fourth  grade  of  school;  in  a  peninsula  on  the  east 
coast  of  Chesapeake  Bay  the  defect  is  dwarf ness  of  stature;  in  George 
Island  and  Abaco  (Bahama  Islands)  it  is  idiocy  and  blindness  (G.  A. 
Penrose,  1905).  There  is  thus  no  one  trait  that  results  from  the  mar- 
riage of  kin ;  the  result  is  determined  by  the  specific  defect  in  the  germ 
plasm  of  the  common  ancestor. 

The  Microbic  Diseases. — It  seems  a  confusion  of  thought  to  the 
student  of  heredity  to  speak  of  the  inheritance  of  any  microbic  disease. 
At  one  time  the  hereditary  transmission  of  microbic  diseases  was  gen- 

*  We  do  not  yet  know  all  the  unit  characters  in  man,  and  it  is  impossible 
to  foretell  which  of  them  are  due  to  positive  determiners  and  which  to  the 
absence  of  such. 


THE    HEEEDITAEY    TEANSMISSION    OF    DISEASE    501 

erally  believed.  Now  we  know  that,  in  the  true  sense  of  the  term,  no 
infectious  disease  is  transmitted  hereditarily — for  even  in  the  case  of 
syphilis  the  Treponema  pallidum  is  carried  in  the  germ  or  sperm  as  a 
foreign  body.  Tuberculosis  at  one  time  was  considered  as  transmitted, 
but  we  now  know  that  this  occurs  so  seldom  that  the  popular  pamphlets 
are  entirely  justified  in  denying  it  entirely. 

Children  are  sometimes  born  with  smallpox,  measles,  and  other  in- 
fections ;  these  are  not  true  instances  of  heredity,  but  cases  of  congenital 
transmission. 

Congenital  Transmission. — Prenatal  infection  is  not  a  true  in- 
stance of  inheritance.  Microbic  diseases  may  be  acquired  by  infection 
through  the  placenta  during  the  fetal  period.  The  placenta  is  a  bet- 
ter filter  for  some  infections  than  for  others.  Thus,  anthrax  and  tuber- 
culosis of  the  mother  are  rarely  transmitted  to  the  fetus,  while  there 
is  great  liability  in  the  case  of  syphilis.  The  fetus  in  utero  may  take 
smallpox,  measles,  and  other  infections,  but  these  instances  are  more 
properly  spoken  of  as  congenital  than  inherited. 

We  must  remember  that  to  be  inherited  on  the  part  of  the  offspring 
or  transmitted  on  the  part  of  the  parents  biology  includes  only  those 
characters  or  their  physical  bases  which  were  contained  in  the  germ 
plasm  of  the  parental  sex  cells  (Martins)  ;  or,  as  Verco  says,  "what 
operates  on  the  germ  after  the  fusion  of  the  sex  nuclei,  modifying  the 
embryo,  or  even  inducing  an  actual  deviation  in  the  development,  can- 
not be  spoken  of  as  inherited.  It  belongs  to  the  category  of  early  ac- 
quired deviations  which  are,  therefore,  frequently  congenital." 

Hereditary  Transmission  of  a  Tendency  to  a  Disease. — While  the 
disease  itself  may  not  be  transmitted,  a  tendency  to  a  disease,  known 
as  a  diathesis,  may  be  transmitted  through  successive  generations.  A 
person  may  inherit  a  small  bony  structure,  a  poor  musculature,  "weak" 
lungs,  susceptible  mucous  membranes,  an  abnormal  amount,  distribu- 
tion, or  development  of  lymphoid  structures,  etc.  In  fact,  we  are  not 
all  born  equal,  and  most  persons  have  some  vulnerable  structure  or  organ 
which  is  commonly  spoken  of  as  their  "weak  point."  In  many  cases  this 
locus  minoris  resistentiae  is  transmitted  as  a  defect  in  structure  or  func- 
tion. 

Davenport  has  collected  the  health  records  and  other  characteris- 
tics furnished  for  over  two  hundred  families  by  members  of  the  fam- 
ilies concerned.  He  finds  certain  definite  facts  in  the  behavior  of  some 
of  the  commoner  diseases.  As  an  example  of  the  inheritance  of  a  gen- 
eral weakness  in  an  organ  he  cites  the  case  of  the  mucous  membranes. 
Thus,  in  one  family  the  principal  diseases  to  which  there  was  liability 
were  located  in  the  mucous  membranes  of  the  nose,  throat,  and  bronchi. 
In  another  family  the  center  of  susceptibility  was  more  .specific,  being 
nearly  confined  to  the  nose  and  throat.     In  another  family  the  weak- 


502     THE    HEREDITARY    TRANSMISSION    OF    DISEASE 

ness  was  in  the  ear;  in  another  the  lungs;  in  another  the  skin;  in  one 
family  the  kidneys  were  the  seat  of  incidence,  etc. 

The  examination  of  the  health  pedigrees  of  a  number  of  families 
impresses  one  by  the  fact  that  the  incidence  of  disease  is  not  always 
haphazard,  for  in  any  large  family  the  various  causes  of  death  do  not 
occur  in  the  proportions  given  in  the  census  table  for  the  population  as 
a  whole. 

Tuberculosis. — V/e  know  that  tuberculosis  is  never  transmitted 
hereditarily,  and  is  seldom  contracted  congenitally.  The  reason  that 
tuberculosis  runs  in  a  family  is  twofold:  (1)  an  inherited  predisposition 
to  the  disease,  and  (2)  increased  chances  of  infection.  Just  what  the 
tendency  or  predisposition  is  is  not  well  understood.  We  do  know, 
however,  that  the  predisposition  is  not  so  great  but  that  it  may  be 
overcome;  the  infection  may  be  avoided  and  the  disease  prevented.  No 
one  is  born  doomed  to  die  of  tuberculosis. 

■  It  is  now  perfectly  plain  that  the  principal  reason  why  tuberculosis 
runs  in  families  is  the  close  association  between  the  infected  and  well 
members  of  the  family,  which  increases  the  chances  of  infection  and  re- 
infection. 

All  persons  inherit  more  or  less  powers  of  resisting  tuberculosis. 
The  inborn  immunity  is  not  marked  in  any  case;  in  some  individuals 
it  is  quite  feeble.  The  border  line  between  immunity  and  susceptibility 
to  tuberculosis  in  the  human  species  is  delicately  balanced  and  may 
readily  be  overturned  (see  page  147). 

Syphilis,. — Syphilis  and  the  consequences  of  syphilis  are  transmitted 
from  parent  to  offspring — "even  unto  the  third  and  fourth  generation." 
Strictly  speaking,  and  in  accordance  with  the  present-day  conception 
of  heredity,  it  may  not  be  proper  to  speak  of  syphilis  as  a  true  instance 
of  heredity,  but  whatever  the  definition  of  words  may  be  the  facts  are 
plain.  The  reason  that  the  student  of  biology  refuses  to  regard  syphilis 
as  well  as  other  microbic  diseases  as  true  instances  of  heredity  is  that  the 
Treponema  'pallidum  is  transmitted  in  the  germ  plasm  as  a  foreign  body, 
and  not  as  a  unit  character.  The  transmission  of  syphilis,  therefore,  does 
not  obey  Mendel's  law.  It  must  be  remembered  that  while  syphilis  itself 
is  not  a  true  instance  of  hereditary  transmission,  the  consequences  of 
syphilis  may  descend  as  inherited  defects  through  many  generations. 
Syphilis  may  be  transmitted  in  three  ways:  (a)  from  the  father  (sperm 
inheritance)  ;  (b)  from  the  mother  (germ  inheritance)  ;  (c)  placental 
transmission  (congenital) .  Osier  summarizes  the  hereditary  transmission 
of  syphilis  as  follows : 

(a)  Paternal  Transmission  {Sperm  Inheritance). — This  is  the  most 
common  form— in  which  the  father  is  infected,  the  mother  being  healthy. 
The  Treponema  pallidum  has  not  yet  been  found  in  the  sperm  cell,  but 
we  do  not  know  its  life  phases,  and  from  what  we  do  know  of  the  life 


THE    HEEEDITAEY    TEANSMISSIOK    OF    DISEASE    503 

history  of  syphilis  it  seems  probable  that  all  the  sperm  cells  are  not 
infective.  A  syphilitic  father  may  beget  an  apparently  healthy  child, 
even  when  the  disease  is  fresh  and  full-bloAvn.  On  the  other  hand, 
in  very  rare  instances  a  man  may  have  had  syphilis  when  young,  undergo 
treatment,  and  for  years  present  no  signs  of  disease,  and  yet  his  iirst 
born  may  show  very  characteristic  lesions.  The  closer  the  begetting  to 
the  primary  sore  the  greater  the  chance  of  infection.  A  man  with  ter- 
tiary lesions  may  beget  healthy  children.  As  a  general  rule,  it  may  be 
said  that  with  judicious  treatment  the  transmissive  power  rarely  exceeds 
three  or  four  years. 

(b)  Maternal  Transmission  (Germ  Inheritance) . — While  the  father 
may  not  be  affected,  in  a  large  number  of  instances  both  parents  are 
diseased,  the  one  having  infected  the  other,  in  which  case  the  chances 
of  fetal  infection  are  greatly  increased.  Transmission  through  the  mother 
alone  is  much  more  fatal  to  the  offspring  than  paternal  transmission.  It 
is  a  remarkable  and  interesting  fact  that  a  woman  who  has  borne  a 
syphilitic  child  is  herself  immune,  and  cannot  be  infected,  though  she 
may  present  no  signs  of  the  disease.  This  is  known  as  Baumes'  or 
Colles'  law,  and  was  thus  stated  by  the  distinguished  Dublin  surgeon: 
■^'That  a  child  born  of  a  mother  who  is  without  obvious  venereal  symp- 
toms, and  which,  without  being  exposed  to  any  infection  subsequent  to 
its  birth,  shows  this  disease  when  a  few  weeks  old,  this  child  will  in- 
fect the  most  healthy  nurse,  whether  she  suckle  it,  or  merely  handle 
and  dress  it ;  and  yet  this  child  is  never  known  to  infect  its  own  mother, 
even  though  she  suckle  it  while  it  has  venereal  ulcers  of  the  lips  and 
tongue."  In  a  majority  of  these  cases  the  mother  has  received  a  sort 
of  protective  inoculation,  without  having  had  actual  manifestations  of 
the  disease.  A  child  showing  no  taint,  but  born  of  a  woman  suffering 
with  syphilis,  may  with  impunity  be  suckled  by  its  mother  (Prof eta's 
law). 

Exceptions  to  Baumes'  law  and  also  to  Colles'  law  are  recorded. 
The  immunity  in  both  cases  is  without  doubt  due  to  "latent"  syphilis, 
that  is  to  an  infection  which  does  not  manifest  itself  clinically. 

(c)  Placental  Transmission. — The  mother  may  be  infected  after  con- 
ception, in  which  case  the  child  may  be,  but  is  not  necessarily,  born 
syphilitic.  If  the  infection  is  late  in  pregnancy,  after  the  seventh  month, 
the  child  usually  escapes. 

Osier  and  Churchman  state  that  syphilitics  may  marry  with  safety 
after  they  have  undergone  three  years  of  thorough  treatment  and  have 
been  without  symptoms  at  least  one  year  after  treatment  has  ceased. 

The  Wassermann  Reaction. — Assent  to  matrimony  should  be  with- 
held from  individuals  with  a  positive  Wassermann  test.  On  the  other 
hand  Iveyes  ^  concludes  that  a  negative  Wassermann  is  not  sufficient 

^Jour.  A.  M.  A.,  Mar.  6th,  1915,  LXIV,  10,  p.  804. 


504    THE    HEEEDITARY    TRANSMISSION    OF    DISEASE 

evidence  of  the  cure  or  absence  of  syphilis.  Again,  a  positive  Wasser- 
mann,  unsupported  by  clinical  evidence,  is  not  sufficient  evidence  of 
the  presence  of  syphilis,  and  therefore  in  itself  does  not  prohibit  matri- 
mony. A  fixed,  positive  Wassermann  in  the  later  years  of  the  disease 
does  not  inevitably  point  to  the  prospect  of  grave  lesions.  A  negative 
Wassermann  after  salvarsan,  in  the  first  year  of  the  disease,  does  not 
mean  that  the  patient  is  cured,  or  that  lesions  will  not  reappear,  because 
the  reaction  may  again  become  positive.  The  return  of  chancre,  glands, 
eruption  and  positive  Wassermann  reaction,  a  few  months  after  control 
of  the  disease  by  salvarsan  in  its  first  few  weeks,  does  not  prove  reinfec- 
tion. 

Cancer. — It  will  prohably  be  a  long  time  before  the  final  word  can 
be  said  concerning  the  iiifluence  of  heredity  in  cancer. 

Maude  Slye  ^  has  studied  the  question  of  inheritance  of  cancer  in  mice 
and  concludes  that  cancer  is  not  inherited,  but  that  a  tendency  to  produce 
cancer  under  the  right  stimulus  is  transmitted  from  generation  to  genera- 
tion. The  stimulus  seems  to  be  over-irritation  at  the  point  where  the 
cancer  arises.  Cancer  can  be  bred  in  and  out  of  strains  of  mice  at  will. 
Cancer  is  transmitted  rather  as  a  tendency  to  occur  from  a  given  provoca- 
tion, an  over-irritation.  The  elimination  of  over-irrigation  in  one  of 
cancer  ancestry  should  materially  lower  the  rate.  Further,  the  eugenic 
control  of  mating  so  that  cancer  shall  not  be  potential  in  both  parents 
would  also  very  materially  decrease  the  incidence  of  human  cancer. 
Tyzzer  has  also  shown  that  a  tendency  to  cancer  is  transmitted  in  experi- 
mental laboratory  animals. 

It  seems  clearly  established  that  certain  chronic  irritating  agencies 
may  produce  cancer,  at  least  in  susceptible  persons.  The  irritation  may 
be  actinic,  thermal,  chemical,  or  mechanical.  Thus  we  have  Rontgen  ray 
epitheliomas;  Kangri  skin  cancer  of  India,  the  epitheliomas  on  the  arms 
of  paraffin  makers,  chimney-sweep's  cancer  of  England,  and  also  the  brand 
cancer  of  cattle.  Each  of  these  present  definite  and  distinct  lesions; 
each  has  a  constant  etiology,  clinical  course,  and  pathology.  To  this 
same  group  also  belongs  the  buyo  cheek  cancer  of  the  Philippine  Islands 
caused  by  chewing  buyo,  the  irritating  agent  of  which  appears  to  be 
lime. 

The  Commission  on  Cancer  of  the  Medical  Society  of  the  State  of 
Pennsylvania  found  that  39  per  cent,  of  the  superficial  cancers  and  46 
per  cent,  of  the  deep-seated  cancers  are  preceded  by  a  precancerous  condi- 
tion or  a  chronic  irritation.  In  other  words,  in  almost  one-half  of  the 
patients  that  are  sent  to  the  surgeon  with  a  fully  developed  cancer  there 
has  been  a  previous  condition  which  might  have  been  cured  and  cancer 
might  not  have  developed.  Superficial  cancers  frequently  exist  for  a 
year  and  a  half  before  they  come  to  the  surgeon. 

^Jour.  Med.  Res.,  1915,  Vol.  32,  p.  168. 


THE    HEEEDITARY    TRANSMISSION    OF    DISEASE    505 

Warthin  ^  from  studies  of  a  long  series  of  cases,  believes  that  a  marked 
susceptibility  to  carcinoma  exists  in  the  ease  of  certain  family  genera- 
tions and  family  groups.  This  susceptibility,  he  thinks,  is  frequently 
associated  with  a  marked  susceptibility  to  tuberculosis  and  also  with 
reduced  fertility.  The  multiple  occurrence  of  carcinoma  in  a  family 
generation  practically  always  means  its  occurrence  in  a  preceding  genera- 
tion. The  family  tendency  is  usually  more  marked  when  carcinoma 
occurs  in  both  maternal  and  paternal  lines.  Family  susceptibility  to 
carcinoma  is  shown  particularly  in  the  case  of  carcinoma  of  the  mouth, 
lip,  breast,  stomach,  intestines,  and  uterus.  In  a  family  showing  the 
occurrence  of  carcinoma  in  several  generations  there  is  a  decided  tendency 
for  the  tumor  to  develop  in  the  breast  of  the  youngest  generations.  In 
this  case  the  tumors  often  show  an  increased  malignancy.  Levin's  study 
of  cancerous  fraternities  leads  him  to  believe  that  the  cancerous  members 
correspond  very  closely  to  the  Mendelian  percentage  of  members  with 
recessive  unit  characters  in  a  hybrid  generation.  Levin  concludes  that 
resistance  to  cancer  is  a  dominant  character  whose  absence  creates  a  sus- 
ceptibility to  cancer.  While  some  of  Warthin's  cases  show  a  family  his- 
tory suggesting  this  form  of  inheritance,  others  indicating  a  progressive 
degenerative  inheritance,  that  is,  the  running  out  of  a  family  line  through 
the  gradual  development  of  an  inferior  stock,  particularly  as  far  as 
resistance  to  tuberculosis  is  concerned. 

Statistical  studies  indicate  that  cancer  is  on  the  increase.^ 

Leprosy  was  formerly  regarded  as  one  of  the  inherited  infections. 
Leprosy  is  not  transmitted.  The  children  of  lepers  born  out  of  leper 
districts,  in  England  or  the  United  States,  for  example,  never  inherit  it. 
The  disease  is  contracted  after  birth,  as  tuberculosis  and  other  microbic 
diseases  are  contracted. 

Deaf -mutism. — Deaf-mutism  is  due  to  a  great  variety  of  causes,  but 
in  different  individuals  of  the  same  family  the  chances  are  large  that  it  is 
due  to  the  same  defect.  This  defect  is  frequently  recessive,  that  is,  hidden 
in  the  normal  children.  Two  such  normal  children  who  are  cousins  but 
from  deaf-mute  stock  tend  to  have  about  one-fourth  of  their  offspring 
deaf-mutes.  The  proportion  of  deaf  offspring  is  thrice  as  great 
among  cousin  marriages  as  among  others.  The  conclusions  of  Fay,  based 
on  extensive  statistics,  deserve  to  be  widely  known.  "Under  all  circum- 
stances it  is  exceedingly  dangerous  for  a  deaf  person  to  marry  a  blood 
relative,  no  matter  whether  the  relative  is  deaf  or  hearing,  nor  whether 
the  deafness  of  either  or  both  or  neither  of  the  partners  is  congenital, 
nor  whether  either  or  both  or  neither  have  other  deaf  relatives  besides 
the  other  partner." 

^Warthin,  A.  S.:  Heredity  with  Eeference  to  Cancer.  Arch.  Int.  Med., 
Chicago,  Nov.,  XII,  5,  pp.  48.5-612. 

^  Frederick  L.  Hoffmann,  "The  Mortality  from  Cancer  Throughout  the 
World."     Also  Bull.  8,  Amer.  Soc.  for  the  Control  of  Cancer. 


506    THE    HEEEDITAEY    TRANSMISSION    OF    DISEASE 


Albinism. — Albinism  belongs  to  a  class  of  cases  resulting  from  the 
absence  of  a  character  or  quality — in  this  instance  the  absence  of  a  pig- 
ment determiner.  Two  albino  parents  have  only  albino  children.  Nor- 
mal offspring  of  an  albino 
and  a  pigmented  parent  may 
transmit  the  albinic  con- 
dition. 

Albinism  is  an  extreme 
case  of  blondeness,  all  pig- 
ment being  absent  from 
skin,  hair,  and  eyes.  The 
method  of  inheritance  re- 
sembles that  of  eye  color. 
When  both  parents  lack 
pigment,  all  offspring  are 
likewise  devoid  of  pigment. 
When  one  parent  only  is  an 
albino  and  the  other  is  un- 
related, then  the  children 
are  all  pigmented.  When- 
ever pigmented  parents  have 
albino  children,  the  pro- 
portion of  the  albinos  ap- 
proaches the  ideal  and  ex- 
pected Mendelian  propor- 
tions— 25  per  cent.  Daven- 
port points  out  that  albinos 
may  avoid  albinism  in  their 
offspring  by  marrying  un- 
related pigmented  persons. 
Pigmented  persons  belong- 
ing to  albinic  strains  must 
avoid  marrying  cousins, 
even  pigmented  ones,  be- 
cause both  parents  might, 
in  that  case,  have  albinic 
germ  cells  and  produce  one 
child  in  four  albinic.  Al- 
bino communities,  of  which 
there    are    several    in    the 


United  States,  are  inbred  communities,  but  not  all  inbred  communities 
contain  albinos. 

Color-blindness,  or  Daltonism. — Color-blindness,  or  daltonism,  is  a 
condition  probably  not  localized  in  the  eyes,  but  due  to  some  defect  in 


THE    HEEEDITARY    TRANSMISSION    OF    DISEASE    507 

the  central  nervous  structure.  It  is  transmitted  hereditarily.  Color- 
blindness is  much  connnoner  in  men  than  in  women.  A  color-blind  man, 
however,  does  not  transmit  color-blindness  to  his  sons;  the  daughters, 
also,  are  themselves  normal,  provided  the  mother  was,  yet  the  daugh- 
ters transmit  color-blindness  to  half  their  sons.  A  color-blind  daughter 
could  be  produced  apparently  only  by  the  marriage  of  a  color-blind  man 
with  a  woman  who  transmits  color-blindness,  since  the  daughter,  to  be 
color-blind,  must  have  received  this  unit  character  from  both  parents, 
whereas  the  color-blind  son  receives  the  character  only  from  his  mother; 
that  is,  the  condition  is  sex-limited. 

Color-blindness  is  apparently  due  to  a  defect  in  the  germ  cell — 
absence  of  something  normally  associated  there,  with  an  X-structure 
which  is  represented  twice  in  women,  once  in  men. 

The  following  interesting  family  history,  studied  by  Horner,  shows 
the  hereditary  persistence  of  color-blindness  and  its  transmission  to  male 
offspring  through  normal  females. 

M 


F 

1^ 


M 

I 


I 
F 

I 
M 


I 
F 

I 
M 


M 

F 


M 

F 


M 


M       M 


I      I      I      I      I       I        I       I       I       I 
FMMFFM     MMF     F 


I      I       I      I      I 
M    F    F    F    F 


M=Male. 

F=  Female. 

Bold-faced  type = Color-blind  subjects. 

The  following  pedigree  of  a  family  containing  color-blind  members 
was  worked  out  by  Dr.  Rivers  among  the  Todas,  an  Indian  tribe : 


- 

1 

1 

1 

M 

I 

1 

1    1 
F  F 

r 

1 
F 

1 
F 

F          M 

1 

1        1         1 
F      F      M 

1 

M         M 
1 

1     1     1 
MMF 

F 

1 
M 

1      1      1      1 
F  M  F   F 

II      Mill 

MM    M  M  M  M  F 
1 

I    I 

M    M 


508    THE    HEREDITARY    TRANSMISSION    OF    DISEASE 

Hemophilia. — Hemophilia  is  a  condition  in  which  the  blood  does 
not  coagulate  properly,  and  those  having  this  condition  may  bleed  to 
death  from  minute  wounds.  It  is  transmitted  hereditarily  and  is  largely 
confined  to  males,  although  transmitted  by  normal  females.  It  is  one 
of  the  best  instances  of  an  hereditable  character,  sex-limited. 

M     P 

! I 

I       


I  I  I  I  I  I 

M  F  M  F  M  M 


I     I      I     I     I     I      I      I     I     I        I  I     I      I       I      I      !       I     I      I       I     I     F 

MFFMMMFMMF      F        MMMFMFMMFMM 


MF  MF         MFMF    MF  FMFMF        FMF        MF 

(Bold-faced  type  indicates  bleeders.) 

The  foregoing  case,  given  by  Klebbs,  is  instructive  in  showing  how 
the  tendency,  though  transmitted  through  daughters,  finds  expression 
only  in  the  males,  and  in  illustrating  first  a  diffusion  and  then  a  wan- 
ing of  the  peculiarity  (Thompson). 

Gout. — It  is  known  that  gout  runs  in  families,  but  just  what  the 
predisposition  is  that  favors  this  condition  of  deranged  metabolism  is 
not  known.  During  four  centuries  one  family  history  showed  that  out 
of  535  gouty  subjects  309  had  a  family  taint — about  60  per  cent.  In 
another  family  out  of  156  cases  140  had  a  family  taint — about  90  per 
cent.  Statistics  show  that  in  from  50  to  60  per  cent,  of  all  cases  the 
disease  existed  in  the  parents  or  grandparents.  It  seems  clear  that  some 
predisposing  factor  may  be  transmitted  hereditarily,  but  in  any  individual 
case  it  is  not  always  plain  how  much  is  due  to  heredity  and  how  much 
to  environment. 

Brachydactylism. — A  typical  example  of  an  abnormality  transmitted 
hereditarily  is  that  of  brachydactylism,  or  short-fingeredness,  a  condition 
in  which  each  digit  comprises  only  two  phalanges — the  fingers  are  all 
thumbs.  This  condition  seems  to  be  due  to  an  inhibition  of  the  normal 
growth  process,  that  is,  normality  implies  entire  absence  of  the  deter- 
miner that  stops  the  growth  of  the  fingers  in  the  brachydactyl.  Thus,  a 
brachydactyl  person  married  even  to  a  normal  person  will  beget  100  per 
cent,  or  50  per  cent,  abnormals,  according  to  circumstances;  but  two 
parents  who,  though  derived  from  brachydactyl  strains,  altogether  lacking 
the  determiner  which  inhibits  the  growth  of  the  fingers  may  have  only 
normal  children. 

According  to  Punnett,  brachydactylism  is  a  good  example  of  a  simple 
Mendelian  case.  It  behaves  as  a  simple  dominant  to  the  normal;  that 
is,  it  depends  upon  a  factor  which  the  normal  does  not  contain.     The 


THE    HEEEDITAEY    TEANSMISSION    OF    DISEASE    509 

recessive  normals  cannot  transmit  the  affected  condition  whatever  their 
ancestry.  Once  free,  they  always  remain  free,  and  can  marry  other  nor- 
mals with  full  confidence  that  none  of  their  children  will  show  the 
deformity. 

Polydactylism. — Polydactylism  is  a  condition  in  which  there  are 
supernumerary  fingers  or  toes.  This  is  a  defect  which  may  be  trans- 
mitted through  successive  generations.  Other  defects  of  the  fingers  and 
toes  are  transmitted  in  accordance  Math  Mendelian  expectation. 

Frag^litis  Ossium. — Fragilitis  ossium,  or  osteopsathyrosis,  a  weakness 
of  the  long  bones,  may  arise  from  a  number  of  pathological  conditions 
affecting  the  bones.  But  the  typical  fragilitis  ossium  or  brittle  bones 
runs  through  families.  Davenport  and  Conrad  ^  have  shown  that  the 
factor  which  determines  the  deficient  bone  formation  is  a  dominant  one. 
Different  degrees  of  the  condition  are  transmitted  true  to  type.  Thus  in 
some  families  the  slightest  pressure  results  in  fracture ;  in  other  families 
the  bones  are  fairly  resistant.  The  association  of  blue  sclerotics  with 
brittle  bones  has  often  been  pointed  out;  the  condition  of  blue  sclerotics 
also  appears  to  be  a  dominant  trait. 

Myopia. — Myopia  can  hardly  be  called  a  disease  in  the  strict  sense, 
being  rather  a  structural  defect  in  the  focusing  power  of  the  optical 
apparatus.  It  seems  that  the  structural  peculiarity  which  leads  to  short- 
sightedness is  transmitted. 

Cataract. — ^Bateson  and  others  have  collected  pedigrees  in  which 
cataracts  run  in  families.  Presenile  cataract  especially  appears  to  be 
transmitted  hereditarily. 

Retinitis  Pigmentosa. — Eetinitis  pigmentosa  is  a  degenerative  disease 
of  the  retina  which  is  transmitted  hereditarily.  jSTormals  may  carry 
the  disease,  so  that  two  normal  cousins  from  retinitis  stock  may  have 
offspring  with  retinitis.  A  large  percentage  of  cases  of  retinitis  come 
from  consanguineous  marriages. 

Diabetes  Mellitus. — Hereditary  influences  seem  to  play  an  important 
role  in  diabetes  mellitus,  for  cases  are  on  record  of  its  occurrence  in  many 
members  of  the  same  family.  Thus,  out  of  104  cases  of  diabetes  mellitus 
22  had  a  family  taint — about  20  per  cent.  ISTaunyn  obtained  a  history  of 
diabetes  in  35  out  of  201  private  cases,  but  in  only  7  of  157  hospital 
cases. 

Orthostatic  Albuminuria. — Orthostatic  albuminuria  occurs  in  boys 
more  commonly  than  girls.  These  are  often  the  children  of  neurotic 
parents,  and  have  well-marked  vasomotor  instability.  Defects  or  pe- 
culiarities in  the  filtering  apparatus  in  the  kidneys  may  arise  as  a 
germinal  variation  and  be  handed  on  from  generation  to  generation. 
Under  conditions  which  may  mean  nothing  to  normal  subjects  this  defect 

*  Davenport,  C.  B.  and  Conrad,  H.  S. :  "Heredity  Fragility  of  Bone,"  Proc. 
Nat.  Acad.  8c. ,  1915,  i,  537. 


510    THE    HEREDITARY    TRANSMISSION    OF    DISEASE 

in  the  kidney  may  find  expression  in  active  disease.  In  this  case,  as  in 
gout,  it  may  not  bo  proper  to  speak  of  the  disease  itself  being  transmitted 
hereditarily,  but  the  tendency  to  deviate  is  so  transmitted. 


2    f^ 


m    f-i 


j-i    fe 


I      =3 


C 
O 

U 


Alcoholism. — Alcohol  as  well  as  lead  and  other  poisons  can  damage 
the  germ  cell  of  the  male  in  such  a  way  as  to  express  itself  by  defective 
offspring.     (Eauschkinder,  or  Jagchildren.)     It  is  a  common  observation 


THE    HEREDITAEY    TRANSMISSION    OF    DISEASE    511 

that  among  the  offspring  of  drunkards  are  many  cases  of  unhealthy,  in- 
sane, and  criminal  types.  The  disastrous  results  may  be  manifested  by 
nervous  disorders,  varying  from  hyperexcitability  to  dementia;  or  as  de- 
bility and  lack  of  developmental  vigor  expressed,  for  instance,  in  infan- 
tilism, want  of  control,  imbecility,  or  as  structural  abnormalities,  espe- 
cially of  the  head  and  brain.  The  results  are  so  varied,  they  suggest  that 
what  is  inherited  is  general  rather  than  specific.  Thus,  the  offspring  of 
alcoholic  parents  are  not  necessarily  predisposed  in  any  one  particular 
direction,  except  that  the  nervous  system  is  most  liable  to  be  affected. 
They  may  be  epileptic,  idiotic,  insane,  etc.  On  the  other  hand,  it  is  neces- 
sary to  recognize  that  what  may  be  inherited  is  not  the  result  of  alcohol- 
ism, but  rather  the  predisposition  which  led  the  parent  to  become  alco- 
holic. This  is  clearly  illustrated  in  cases  where  the  parent  did  not  acquire 
the  alcoholic  habit  until  after  the  children  were  born.  Clouston  observes 
that  "it  is  not  the  craving  for  alcohol  that  was  inherited,  but  a  general 
psychopathic  constitution  in  which  the  alcoholic  stimulus  is  an  undue 
stimulus  and  the  mental  control  deficient."     (See  page  338.) 

Migraine. — That  migraine  is  transmitted  hereditarily  is  indicated 
from  the  family  histories  of  those  suffering  with  this  affection. 

Anaphylaxis,  or  Food  Idiosyncrasies. — Both  experimental  evidence,  as 
well  as  family  histories,  clearly  indicate  that  hypersusceptibility  to  certain 
foods,  such  as  egg,  shellfish,  strawberries,  tomatoes,  etc.,  is  transmitted 
hereditarily  through  several  generations.  The  transmission  is  sometimes 
specific  and  limited  to  one  particular  food.     (See  page  462.) 

Epilepsy. — Brown-Sequard  showed  conclusively  that  artificially  in- 
duced epilepsy  in  the  guinea-pig  is  transmissible.  The  statistics  col- 
lected for  man  give  from  9  to  over  40  per  cent,  of  cases  in  which  heredity 
is  an  important  predisposing  cause.  Gowers  gives  35  per  cent,  for  his 
cases.  In  the  Elwyn  cases  32  of  the  126  gave  a  family  history  of  nervous 
derangement  of  some  sort,  either  paralysis,  epilepsy,  marked  hysteria,  or 
insanity.  Thom's  ^  study  of  1,536  epileptics  at  the  Monson  State  Hos- 
pital (Mass.)  would  make  it  appear  that  epilepsy  is  transmitted  directly 
from  parents  to  offspring  less  frequently  than  we  have  heretofore  been 
led  to  believe. 

Chronic  alcoholism  in  the  parents  is  also  regarded  as  a  potent  pre- 
disposing factor  in  the  production  of  epilepsy.  Echeherria  has  analyzed 
572  cases  bearing  upon  this  point,  and  divided  them  into  three  classes,  of 
which  257  cases  could  be  traced  directly  to  alcohol  as  the  cause,  126 
cases  in  which  there  were  associated  conditions,  such  as  syphilis  and 
traumatism,  189  cases  in  which  alcoholism  was  probably  the  result  of 
the  epilepsy.  Figures  equally  strong  are  given  by  Martin,  who,  in  150 
insane  epileptics,  found  83  with  a  marked  history  of  paternal  intem- 
perance. Of  the  126  Elwyn  cases  in  which  the  family  history  of  this 
^Boston  M.  and  8.  Journal,  CLXXIV,  16,  April  20,  1916,  p.  573. 


512     THE    HEKEDITARY    TRANSMISSION    OF    DISEASE 

point  was  carefully  investigated,  a  definite  statement  was  found  in  only 
4  of  the  cases  (Osier). 

Huntington's  Chorea. — Huntington's  chorea  is  frequently  inherited. 


O      g 


03 


w  s 


CD      1^1 


The  disease  is  known  as  chronic  hereditary  chorea.  It  was  described  by 
Lyon  in  1863,  who  traced  the  disease  through  five  generations.  Hunt- 
ington in   1873  gave  the  three   salient  points   in   connection  with  the 


THE    HEREDITARY    TRANSMISSION    OF    DISEASE    513 

disease,  viz. :   ( 1 )  its  hereditary  nature ;   ( 2 )  association  with  psychical 
troubles;  and  (3)  late  onset  between  the  thirtieth  and  fortieth  year. 

Huntington's  chorea  is  a  typical  dominant  trait.  The  normal  con- 
dition is  recessive;  in  other  words,  the  disease  is  due  to  some  positive 
determiner.  Persons  with  this  dire  disease  should  not  have  children, 
but  the  members  of  normal  branches  derived  from  the  affected  strain 
are  immune  from  the  disease.  This  disease  forms  a  striking  illustra- 
tion of  the  principle  that  many  of  the  rarer  diseases  of  this  country 
can  be  traced  back  to  a  few  foci,  even  to  a  single  focus ;  certainly  in  this 
case  many  of  the  older  families  with  Huntington's  chorea  trace  back  to 
the  New  Haven  colony  and  its  dependencies  and  subsequent  offshoots 
(Davenport). 

Friedreich's  Disease — Hereditary  Ataxia. — This  disease  resembles 
locomotor  ataxia,  although  differing  from  it  in  several  essential  par- 
ticulars. It  begins  in  childhood  and  usually  occurs  in  a  family  having 
other  members  of  the  family  affected  with  the  same  disease.  There 
are  curious  forms  of  incoordination  and  loss  of  knee-jerk,  early  talipes 
equinus,  scoliosis,  nystagmus,  and  scanning  speech.  The  affection  lasts 
for  many  years  and  is  incurable.  In  1861  Friedreich  reported  six  cases 
of  this  form  of  ataxia  in  one  family.  Since  then  it  has  usually  been 
observed  to  be  a  family  disease,  and  is,  therefore,  assumed  to  be  trans- 
mitted hereditarily.  The  eugenic  teaching  in  this  affection,  according 
to  Davenport,  is  that  normal  members  of  the  affected  fraternities  should 
marry  only  outside  the  strain.  Whether  all  cases  of  ataxic  offspring  of 
one  normal  parent  are  derived  from  consanguineous  marriage  is  still  un- 
certain and  warrants  hesitation  in  advising  the  marriage  of  any  ataxic 
person. 

Mental  Deficiency. — This  term  includes  imbecility,  idiocy,  feeble- 
mindedness and  psychopathic  inferiority,  etc.  In  this  class  we  have  one 
of  the  best  examples  of  a  pathological  condition  transmitted  by  inheri- 
tance. Davenport  believes  that  imbecility  is  due  to  the  absence  of  some 
definite  simple  factor,  on  account  of  the  simplicity  of  its  method  of  inher- 
itance. Two  imbecile  parents,  whether  related  or  not,  have  only  imbecile 
offspring.  Davenport  states  that  there  is  no  case  on  record  where  two 
imbecile  parents  have  produced  normal  children. 

Dr.  H.  H.  Goddard,  of  the  Training  School  for  Feeble-Minded,  at 
Vineland,  K.  J.,  has  studied  the  ancestry  of  children  in  the  Vineland 
institution  and  has  found  almost  without  exception  a  history  of  feeble- 
mindedness for  several  generations.  Dr.  Goddard's  remarkable  study  of 
the  Kallikak  family  has  already  been  referred  to.  In  this  instance  he 
traced  the  ancestry  of  a  22-year-old  girl  through  about  1,100  individuals 
as  far  back  as  the  Revolutionary  War.  Similar  studies  are  being  carried 
out  in  other  institutions  and  always  with  similar  results.  The  subject  is 
fully  discussed  on  page  476. 
18 


514    THE    HEEEDITARY    TRANSMISSION    OF    DISEASE 

Insanity. — Insanity  is  a  general  term  comprising  many  different 
conditions.  No  general  statement  can,  therefore,  be  made  except  that 
certain  forms  of  insanity  are  undoubtedly  transmitted  through  succes- 


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sive  generations.  It  is  safe  to  say  that  heredity  is  responsible  for  more 
cases  of  mental  diseases  than  any  other  single  cause.  Mental  diseases 
are  rare  in  persons  free  from  ancestral  taint,  except  as  the  result  of 
wounds  or  toxic  influences. 


THE    HEEEDITAEY    TEANSMISSION    OF    DISEASE    515 

Practically  all  the  statistics  accumulated  on  insanity  have  limited 
value  to  the  student  of  heredity,  because  they  do  not  give  numerical 
records  of  the  sane  members  of  the  families  of  the  insane.  The  subject  is 
fully  discussed  in  Chapter  VI,  page  331. 

REFERENCES 

Lock,  E.  H. :  'Tariation,  Heredity,  and  Evolution,"  1910. 

Huxley,  T.  H. :  "Collected  Essays,"  Vol.  2,  1899. 

Lamarck,  J.  B. :  "Philosophie  Zoologique,"  1809. 

Darwin,  Chas. :  "The  Origin  of  Species,"  6th  Edition,  1873. 

Weismann,  A.:  "Essays  Upon  Heredity,"  1889;  "The  Variation 
Theory,"  1906;  "The  German  Plasm:  A  Theory  of  Heredity"  (trans- 
lated by  W.  N.  Parker  and  H.  Eonnfeld,  1893). 

Galton,  F. :  "Natural  Inheritance,"  1889;  "Hereditary  Genius," 
1869;  "English  Men  of  Science,"  1874;  "Inquiries  Into  Human  Faculty 
and  Its  Development,"  1883;  "Natural  Inheritance,"  1889;  "Eugenics: 
Its  Definition,  Scope,  and  Aims,"  1905. 

Davenport :    "Statistical  Methods,"  1904 ;  "Heredity  in  Eelation  to 
Eugenics,"  1911. 

Pearson,  K. :  "The  Grammar  of  Science,"  2d  Edition,  1900. 

Bateson,  W. :  "Materials  for  the  Study  of  Variation,"  1894;  "Men- 
del's Principles  of  Heredity,"  1909. 

DeVries,  H. :  "Die  Mutationstheorie,"  1901 ;  "Species  and  Varieties : 
Their  Origin  by  Mutation,"  1905. 

Wilson,  E.  B. :  "The  Cell  in  Development  and  Inheritance,"  2d  Edi- 
tion, 1900. 

Thompson,  J.  A. :  "Heredity,"  1908. 

Castle,  William  E. :  "Heredity,"  1911. 

The  Proceedings  of  the  Roy.  Soc.  of  Medicine,  1909,  Vol.  II :  "The 
Influence  of  Heredity  on  Disease,"  with  Special  Eeference  to  Tubercu- 
losis, Cancer,  and  Diseases  of  the  Nervous  System. 

Punnett,  E.  C. :  "Mendelism,"  1911. 


SECTION  III 
FOODS 

CHAPTEE  I 
GENERAL  CONSIDERATIONS 

Foodstuffs  fall  naturally  into  two  great  divisions:  (1)  those  de- 
rived from  the  animal  kingdom,  and  (2)  from  the  plant  kingdom. 
The  animal  foods  are  much  more  apt  to  convey  infections  or  to  pos- 
sess injurious  properties  than  foods  derived  from  plant  life.  Of  the 
animal  foods  meat  and  milk  are  the  chief  offenders.  Water  ordinarily 
is  not  classed  as  a  food,  and  is  discussed  in  a  separate  chapter. 

The  increase  of  food  poisoning  and  the  increase  of  diseases  caused 
by  infected  foods  are  more  apparent  than  real.  The  subject  is  better 
understood,  and  cases  are  now  recognized  and  reported  that  were  for- 
merly misinterpreted.  The  hygienic  conscience  of  the  people  has  been 
aroused,  and  a  demand  has  been  established  for  clean,  fresh,  wholesome 
foodstuffs.  The  separation  of  the  producer  and  the  consumer  and  the 
demands  of  large  cities  have  made  these  sanitary  reforms  eminently 
necessary.  The  pure  food  laws,  the  meat  inspection  act,  the  milk  or- 
dinances, and  the  local  surveillance  over  markets,  provision  shops, 
dairies,  etc.,  are  all  part  of  the  general  movement  to  obtain  a  reason- 
ably decent  and  safe  food  supply. 

People  should  be  educated  to  demand  flesh  from  healthy  animals, 
cut  up  and  handled  in  a  careful  manner  by  butchers  free  from  dis* 
ease,  and  to  demand  garden  truck  grown  in  clean  dirt  and  not  in  soil 
polluted  with  human  excrement.  Food  must  be  guarded  in  trans- 
portation and  purveyed  in  markets  and  shops  so  as  to  be  protected  from 
flies,  rats,  dust,  and  unnecessary  human  contact. 

The  prophylactic  and  therapeutic  uses  of  food  are  growing  subjects. 
It  is  only  necessary  to  point  out  the  importance  of  diet  in  the  preven- 
tion and  treatment  of  beri-beri,  scurvy,  pellagra,  tuberculosis,  diabetes, 
nephritis,  arteriosclerosis,  gout,  rheumatic  affections,  disorders  of 
metabolism,  dyspepsia,  gastric  ulcer,  infantile  diarrheas,  and  many  other 
affections. 

The  proper  amount  and  quality  of  food  is  one  of  our  important  pre- 
ventive measures. 

516 


GENERAL    CONSIDERATIONS  517 

Food  may  affect  health  in  a  great  variety  of  ways : 

(a)  Eoods  may  be  naturally  poisonous,  as  in  the  case  of  certain 
mushrooms,  some  fish,  or  the  alkaloids  in  various  species  of  plants. 

(b)  Poisonous  substances  may  develop  in  the  food  as  a  result  of 
bacterial  activity,  as  sausage  poisoning  (botulism).  In  this  class  are 
also  included  the  so-called  pto mains  or  putrefactive  poisons. 

(c)  Foods  may  convey  foreign  or  accidental  poisons.  This  class 
includes  mostly  the  metallic  poisons  and  chemicals  added  as  adulterants, 
as  lead,  copper,  arsenic,  formaldehyd,  sulphites,  etc. 

(d)  Foods  may  contain  animal  parasites,  such  as  trichina  and  tape- 
worms.    These  infections,  as  a  rule,  occur  as  ante-mortem  infections' 
in  the  animal.     Plant  foods  may  carry  the  eggs  or  larvae  of  various 
animal  parasites. 

(e)  Foods  may  contain  vegetable  parasites.  Both  animal  and  vege- 
table foods  may  convey  bacteria  pathogenic  for  man.  The  harmful 
varieties  are  more  often  found  in  animal  foods  than  upon  plant  foods. 
The  food  animals  may  be  infected  before  death,  or  the  meat  may  become 
infected  while  it  is  being  cut  up  or  handled.  The  best  example  in  this 
class  is  paratyphoid  infection,  sometimes  called  meat  poisoning;  also 
typhoid  bacilli  in  oysters,  or  on  celery,  etc.  Milk  often  contains  patho- 
genic microorganisms. 

(f)  Foods  may  contain  special  poisons,  as,  for  example,  solanin  in 
sprouted  potatoes,  or  ergot  in  rye. 

(g)  Food  may  be  injurious  as  a  result  of  abnormality  of  amount 
or  composition  of  diet.  Thus  an  excess  of  food  predisposes  to  obesity 
and  perhaps  to  arteriosclerosis  and  diseases  of  the  liver  and  kidneys. 
An  insufficient  amount  undermines  health.  A  monotonous  diet,  espe- 
cially of  polished  rice,  leads  to  beri-beri ;  a  faulty  diet,  containing  insuffi- 
cient protein,  leads  to  pellagra;  lack  of  organic  acids  induces  scurvy; 
defective  alimentation,  especially  a  deficiency  of  lime  salts,  pre- 
disposes to  rickets.  Highly  spiced  and  stimulating  diets  are  irritating 
botli  to  the  digestive  tube  and  the  organs  of  excretion.  An  excess  of 
fats  produces  a  condition  resembling  acidosis,  particularly  in  children. 
An  unbalanced  ration  long  continued  is  apt  to  be  harmful.  Thus,  an 
excess  of  protein  induces  putrefactive  changes  with  its  dangers  of  "auto- 
intoxication.' Eating  when  fatigued,  or  improper  mastication,  are  causes 
of  indigestion.     Drinking  too  little  water  is  a  common  dietetic  error. 

(h)  Finally,  foods  may  not  be  poisonous  in  themselves,  but  may  be 
harmful  to  persons  who  lack  ability  to  digest  them  or  lack  the  mechan- 
ism by  which  they  may  be  assimilated.  Thus,  certain  forms  of  pro- 
tein habitually  produce  symptoms  resembling  anaphylaxis  in  persons 
who  are  sensitized.  This  occurs  most  commonly  with  sea  food,  but 
also  takes  place  with  strawberries,  eggs,  tomatoes,  oatmeal  and  a  great 
variety  of  substances. 


518  GENEPtAL    CONSIDERATIONS 


THE    USES    OF    FOOD 

The  two  ultimate  uses  of  all  food  are  to  supply  the  body,  (1)  with 
materials  for  growth  or  renewal,  and  (2)  with  energy  or  the  capacity 
for  doing  work.  The  potential  energy  received  in  a  latent  form  stored 
in  the  various  chemical  combinations  in  foods  is  liberated  as  kinetic 
or  active  energy  in  two  chief  forms,  heat  and  motion.  Force  is  the 
manifestation  of  energy,  and  the  force  developed  by  a  healthy  man  may 
be  measured  in  foot  pounds.  A  foot  pound  is  the  amount  of  energy 
expended  or  force  required  to  lift  mechanically  a  weight  of  one  pound 
to  a  height  of  one  foot. 

The  work  of  an  average  man  is  calculated  at  about  2,000,000  foot 
pounds  per  diem  (R.  H.  Thurston).  This  may  exceptionally  be  in- 
creased to  3,000,000  foot  pounds.  Ordinarily  less  than  one-fifth  of  the 
total  energy  of  the  body  is  expended  in  motion,  and  more  than  four- 
fifths  in  heat  production. 

The  total  intake  of  energy  into  the  body  is  derived  from  food  plus 
the  oxygen  of  the  inspired  air.  The  total  output  of  energy  is  computed 
from:  (1)  the  heat  of  combustion  of  the  unoxidized  ingredients  of  the 
urine  and  feces;  (2)  the  energy  liberated  as  body  heat,  and  (3)  the 
energy  of  external  muscular  work,  or  the  work  of  the  voluntary  muscles 
(Thompson). 

Whether  alimentary  substances  are  burned  outside  of  the  body  or 
oxidized  within  the  body,  the  resulting  waste  products  are  similar.  No 
substance  is  a  good  food  unless  it  fulfills  two  conditions,  viz. :  easy  as- 
similation and  complete  combustion.^ 

Two  methods  may  be  employed  to  study  the  energy-producing  power 
of  food  in  the  body:  (1)  a  careful  and  prolonged  study  of  subjects  who 
are  allowed  to  follow  their  usual  vocations,  but  whose  food  and  excreta  are 
carefully  measured  and  analyzed:  (2)  the  shorter  method  of  enclosing 
a  man  for  a  brief  period,  not  exceeding  a  few  days,  in  a  cabinet  known 
as  a  calorimeter. 

The  unit  of  measurement  is  the  calorie,  which  is  the  amount  of 
heat  required  to  raise  one  kilogram  of  water  from  0°  to  1°  C.  This 
equals  3,100  foot  pounds,  or  approximately  the  heat  required  to  raise 
the  temperature  of  one  pound  of  water  4°  F.  Fuel  value  is  a  term 
denoting  the  total  number  of  calories  derived  from  a  gram  or  pound 
of  any  given  food  substance  if  it  is  completely  combusted  within  the 
body.  The  fuel  values  are  calculated  for  a  given  food  by  the  factors 
of  Eubner  as  follows : 

*  It  is  not  sufficient  to  know  merely  the  amount  and  caloric  value  of  the  coal 
fed  to  a  furnace,  and  subtract  therefrom  the  amount  of  unconsumed  ash.  We 
must  know  how  much  of  the  heat  generated  has  been  utilized. 


CLASSIFICATION    OF   FOODS  519 

4.5  calories  per  gram  of  either  protein  or  carbohydrate. 
9,3  calories  per  gram  of  fat. 

Atwater  and  Bryant  compute  the  food  factors  as  4  calories  per  gram 
for  proteins  and  carbohydrates  and  8.9  for  fats,  in  a  mixed  diet.  C.  F. 
Langworthy  gives  the  fuel  value  of  the  three  chief  classes  of  nutrients 
as  follows: 

1  pound  of  protein  yields 1,860  calories 

1  pound  of  fats    4,220  calories 

1  pound  of  carbohydrates  1,860  calories 

From  a  chemical  standpoint  foods  are  oxidized  or  burned  to  simpler 
compounds  during  the  process  of  digestion  and  metabolism  within  the 
body.  Food  is,  therefore,  fuel.  The  oxygen  to  feed  the  flame  is  mainly 
furnished  by  the  inspired  air,  hence  active  breathing  of  pure  fresh  air 
is  essential  and  one  of  the  best  stimuli  for  complete  metabolism.  It  is 
the  common  experience  of  all  persons  that  digestion  and  the  utilization 
of  foods  are  favorably  promoted  by  life  in  the  open  air. 

The  nutritive  value  of  a  diet  does  not  depend  wholly  upon  its  calorific 
value.  The  importance  of  flavors,  spices,  and  the  preparation  of  food 
depends  not  alone  upon  the  application  of  chemistry  and  physics,  but 
also  upon  physiology. 

The  discovery  of  the  vitamins  has  emphasized  the  value  of  those 
elements  of  food  which  although  present  in  minute  amounts  exert  a 
determining  influence  in  the  utilization  of  the  ordinary  articles  of  diet. 
The  immense  practical  importance  of  these  hitherto  unknown  factors 
has  been  shown  in  the  case  of  beri-beri,  and  probably  in  the  case  of 
scurvy,  pellagra  and  other  "dietetic"  and  "constitutional"  ailments. 


CLASSIFICATION    OF    FOODS 

Foods  may  be  classed  in  various  ways.  Thompson  divides  them 
into  four  groups,  according  to  (1)  their  physical  properties,  (2)  their 
source,  (3)  their  composition,  and  (4)  their  function,  or  the  role  which 
they  perform  in  the  animal  body. 

Physical  Properties. — Foods  are  classed  in  accordance  with  their 
general  physical  properties  first  into  solid,  semisolid,  and  liquid  foods; 
secondly,  into  fibrous,  gelatinous,  starchy,  oleaginous,  crystalline,  and 
albuminous  foods.  Foods  are  also  classed  as  foods,  beverages,  and  con- 
diments. 

Sources. — Foods  may  be  classed  as  to  their  source  primarily  into  (a) 
animal  and  (b)  plant  foods. 


520  GENEEAL    CONSIDEEATIONS 

Animal  foods  consist  of  meat,  fowl,  fish,  shellfish,  crustaceans,  in- 
sects and  their  products  (honey),  eggs,  milk  and  its  products,  animal 
fats,  gelatin. 

The  plant  foods  are  subdivided  into  cereals,  vegetables  proper,  fruits, 
sugar,  gums,  vegetable  oils  and  fats. 

Composition  and  Function. — The  simplest  chemical  classification 
possible  is  that  advocated  by  Liebig,  who  was  the  first  to  suggest  a 
really  scientific  definition  of  foods.  He  grouped  all  foods  into  two 
classes :  nitrogenous  and  non-nitrogenous.  Each  of  these  classes  con- 
tains food  materials  from  both  the  animal  and  vegetable  kingdoms, 
although  the  majority  of  the  animal  substances  belong  to  the  nitroge- 
nous and  the  majority  of  the  vegetable  substances  to  the  non-nitrogenous 
group. 

Nitrogenous  foods  contain  proteins  and  include  gelatinoids  and  al- 
buminoids, substances  which  resemble  albumin.  They  consist  chiefiy 
of  the  four  elements :  carbon,  oxygen,  hydrogen,  and  nitrogen,  to  which 
a  small  proportion  of  sulphur  and  phosphorus  is  usually  joined.  The 
nitrogenous  foods  were  regarded  by  Liebig  as  containing  plastic  ele- 
ments; that  is,  they  are  essentially  tissue  builders  or  flesh  formers. 
The  non-nitrogenous  group  Liebig  called  respiratory  or  calorifacient 
foods,  because  their  function  in  the  body  is  largely  to  furnish  fuel  to 
maintain  animal  heat.  It  is  now  known  that  the  non-nitrogenous  foods 
supply  energy  for  muscular  action,  hence  they  are  also  called  force 
producers,  to  distinguish  them  from  the  nitrogenous  or  tissue  builders. 
This  is  a  convenient  distinction,  but  it  must  not  be  held  too  absolutely, 
for  in  certain  conditions  the  tissue  builders  are  used  as  force  and  heat 
producers  as  well. 

Classification. — Foods  are  now  ordinarily  classed  as:  (1)  nitrogenous; 
(2)  starchy;  (3)  oily,  and  (4)  condimental.  Examples  of  nitrogenous 
foods  are  lean  meat,  the  white  of  eggs,  or  the  casein  in  milk.  The  gluten 
of  wheat  and  the  zein  of  corn  are  also  typical  nitrogeneous  constituents. 
Peas  and  beans  contain  large  percentages  of  nitrogenous  matter.  The 
nitrogenous  or  protein  substances  build  and  repair  tissue,  and  to  a  less' 
extent  serve  as  fuel  to  yield  energy  in  the  forms  of  heat  and  muscular 
power. 

The  starchy  or  carbohydrate  foods  are  represented  by  the  cereals, 
the  tubers,  such  as  potatoes,  the  sugars  of  the  cane,  beet,  fruits,  etc., 
and  glycogen  in  flesh. 

Fats  or  oily  foods  are  represented  by  butter,  olive  oil,  cotton-seed 
and  other  oils,  the  fat  of  meat,  the  oil  of  nuts  and  seeds.  All  vege- 
tables contain  more  or  less  oily  substances.  The  fats  as  fell  as  the 
carbohydrates  serve  as  fuel  to  yield  energy  in  the  form  of  heat  and 
muscular  power. 

Mineral  matter  or  ash  performs  an  important  service  in  forming 


THE  AMOUNT  OF  FOOD  521 

bone  and  assisting  in  digestion  and  metabolism.  These  substances  are 
ordinarily  not  classed  as  foods;  however,  life  cannot  be  maintained 
without  them.     This  applies  also  to  the  vitamines. 

Among  the  condiments  are  classed :  spices,  such  as  pepper,  mustard, 
cinnamon,  cloves,  etc. ;  also  coffee,  tea,  and  alcoholic  beverages. 


THE    AMOUNT    OF    FOOD 

Excessive  Amounts. — The  amount  of  food  required  varies  greatly 
with  conditions.  In  civilized  communities,  where  cooking  is  a  fine  art, 
the  number  and  variety  of  food  preparations  are  so  great  that  the  ap- 
petite is  often  stimulated  beyond  the  requirements  of  the  system,  and 
consequently  more  food  is  eaten  than  is  necessary  or  desirable  to  main- 
tain the  best  bodily  health  and  vigor.  Gluttony  results  in  overdevelop- 
ment and  overwork  of  the  digestive  apparatus;  the  stomach  and  bowels 
become  enlarged;  the  liver  is  engorged,  and  a  predisposition  is  estab- 
lished to  degenerative  changes,  fatty  heart,  etc.  The  quantity  of  food 
required  to  maintain  the  body  in  vigor  varies  with  the  climate  and 
season,  clothing,  occupation,  work,  and  exercise,  the  state  of  individual 
health,  age,  sex,  and  body  weight. 

Both  overeating  and  overdrinking  may  be  temporary  or  chronic. 
When  chronic  it  may  lead  to  such  diseases  or  diatheses  as  obesity,  gout,, 
lithemia,  oxaluria,  or  the  formation  of  renal,  vesical,  and  hepatic  cal- 
culi. It  is  very  certain  to  cause  congestion  of  the  liver  and  the  con- 
dition known  as  "biliousness,"  in  which  the  stomach  and  intestines 
are  engorged,  constipation  results,  the  tongue  is  heavily  coated,  the 
bodily  secretions  are  altered  in  composition,  the  urine  especially  be- 
comes overloaded  with  salts,  the  liver  becomes  congested,  and,  finally, 
the  nervous  and  muscular  systems  are  affected,  which  result  in  the  pro- 
duction of  headache  and  feelings  of  fatigue,  lassitude,  drowsiness,  and 
mental  stupor. 

Insufficient  Food. — Starvation  or  asitia  is  a  term  which  technically 
applies  to  the  lack  of  sufficient  food  for  the  maintenance  of  the  body, 
while  inanition  means  the  lack  of  the  assimilation  of  food  by  the  tis- 
sues. When  food  is  completely  withheld,  life  cannot  be  prolonged  be- 
yond six  or  ten  days  jn  the  majority  of  instances.  Professional  fasters 
have  gone  41  days  without  anything  but  water.  If  food  is  withheld 
suddenly,  the  sensation  of  hunger  gradually  increases,  becomes  extreme, 
lasts  for  two  or  three  days,  and  slowly  disappears.  It  is  accompanied 
by  a  gnawing  pain  in  the  epigastrium,  which  is  relieved  on  pressure. 
The  pain  may  disappear,  but  it  is  followed  by  a  sensation  of  extreme 
weakness  or  faintness,  which  is  both  Ipcal  in  the  stomach  and  general 
throughout  the  body.     Even  though  the  pain  disappears,  the  sensation 


532  .GENERAL    CONSIDERATIONS 

of  hunger  may  occasionally  reassert  itself,  when  all  food  is  withheld, 
until  death,  or  until  the  subject  becomes  insane  or  unconscious. 

Hunger  is  not  always  a  reliable  guide  to  the  need  of  the  system 
for  food.  Some  dyspeptics  are  always  hungry  and  eat  more  than  they 
can  digest.  A  habit  of  rapid  eating  does  not  satisfy  the  sensation  of 
hunger.  More  food  may  be  taken  than  is  necessary,  because  it  has  not 
had  time  to  meet  the  needs  of  the  system  before  the  meal  is  over.  Can- 
non has  shown  that  the  sensations  of  hunger  come  and  go  rhythmically, 
appearing  synchronously  with  the  contractions  of  the  empty  stomach. 

The  statement  is  frequently  made  that,  when  starvation  occurs  upon 
a  large  scale,  affecting  a  community  with  famine,  pestilence  is  sure  to 
accompany  it.  Thus,  disease  has  often  been  rampant  in  Ireland  when, 
the  potatoes  have  failed,  and  in  India  when  the  grain  supply  has  given 
out.  Much  of  the  illness  which  occurred  in  the  early  history  of  the 
Crimea  was  coincident  with  insufficient  food,  and  it  is  stated  that  in 
the  middle  ages  the  ravages  of  pestilential  diseases,  such  as  typhus, 
smallpox,  plague,  etc.,  were  always  worse  in  times  of  general  starva- 
tion. The  history  of  epochs  of  famine  in  siege  or  otherwise  is  always 
accompanied  by  outbreaks  of  violence,  for  hunger  begets  ill  temper,  vice, 
and  crime.  This  has  occurred  of  late  years,  notably  in  Athens,  Flor- 
ence, and  London,  and  in  Paris  during  the  Commune.  There  is,  how- 
ever, no  very  definite  relationship  between  famine  and  epidemics.  The 
depressed  vitality  caused  by  insufficient  food  does  not  account  for  epi- 
demics of  plague,  smallpox,  relapsing  fever,  typhus  fever,  and  other 
pestilential  diseases,  sometimes  called  famine  fevers.  The  reasons  for 
this  have  been  discussed  under  Immunity. 

Unbalanced  Diets. — Unbalanced  diet  may  produce  anemia  from  lack 
of  meat  or  other  food;  scurvy  from  lack  of  fresh  fruits  and  vegetables, 
with  preponderance  of  salty  meat  and  fish ;  rickets  and  marasmus  from 
an  excess  of  amylaceous  and  lack  of  animal  food,  necessary  salts,  etc. ; 
a  form  of  acidosis  from  too  much  fat,  especially  in  babies;  acne  or 
eczema  from  food  too  rich  in  carbohydrates  or  fats;  constipation  from 
too  nutritious  and  concentrated  diet;  and  gout  from  various  dietetic 
errors.  Unbalanced  diets  are  responsible  for  a  long  list  of  affections, 
a  type  of  which  is  beri-beri,  caused  by  a  monotonous  diet  consisting 
chiefly  of  polished  rice.  Pellagra  is  also  attributed  to  a  faulty  diet,  con- 
sisting largely  of  corn  and  a  deficiency  of  proteins. 

The  importance  of  a  mixed  diet  may  be  appreciated  when  we  con- 
sider the  diseases  resulting  from  faulty  metabolism  seen  in  those  persons 
who  subsist  upon  a  one-sided  diet,  lacking  substances  known  as  vitamins 
(Funk).  A  vitamin  is  a  substance  which  is  present  in  minute  quantities 
in  various  foodstuffs ;  a  certain  quantity  must  be  supplied  for  the  organ- 
ism to  maintain  its  normal  metabolism.  The  deprivation  of  one  of  these 
vitamins  results  in  the  production  of  diseased  states.    Thus  scurvy  is  said 


ADULTEEATION  OF  FOOD  523 

to  be  due  to  the  deprivation  of  one  vitamin,  while  beri-beri  is  due  to  the 
deprivation  of  another,  or  perhaps  two  vitamins. 

Salts  in  the  Diet. — Common  organic  or  vegetable  acids,  such  as  citric 
from  lemons  and  oranges,  tartaric  from  grapes,  malic  from  apples, 
etc.,  usually  exist  in  combination  with  the  bases,  calcium,  sodium,  potas- 
sium, etc.,  when  derived  from  fresh  vegetables  and  fruits.  They  are 
indispensable  articles  of  food,  for  when  absorbed  they  form  carbonates, 
which  aid  in  maintaining  the  alkalinity  of  the  blood.  Prolonged  de- 
privation of  them  may  r&sult  in  scurvy.  Lack  of  sufficient  potash  salts, 
especially  potassium  carbonate  and  chlorid,  is  also  a  factor  in  producing 
scurvy,  and  the  condition  is  intensified  by  the  excessive  use  of  common 
salt. 

If  calcium  phosphate  is  deficient  in  the  food  of  the  young,  growing 
infant,  the  bones  are  poorly  developed  and  so  soft  that  they  yield  to 
the  strain  of  the  weight  of  the  body  and  become  bent,  as  occurs  in 
rickets. 

Lack  of  inorganic  salts  in  the  food  impoverishes  the  coloring  matter 
of  the  red  blood  corpuscles  on  which  they  depend  for  their  power  of 
carrying  oxygen  to  the  tissues,  and  anemia  and  other  disorders  result. 
An  ash-free  diet  soon  causes  serious  symptoms. 

Longworthy  gives  the  following  as  the  estimated  amount  of  mineral 
matter  required  per  man  per  day : 

Phosphoric  acid  (P2O5) 3  to  5         grams 

Sulphuric  acid  (SO3) 2  to  3.5 

Potassium  oxid 2  to  3  " 

Sodium  oxid   4  to  6  " 

Calcium  oxid 0.7  to  1.0  " 

Magnesium  oxid 0.3  to  0.5  " 

Iron    0.006  to  0.012      " 

Chlorid    6  to  8  " 


ADULTERATION    OF   FOOD 

Adulteration  of  food  consists  of  a  large  number  of  practices,  some 
of  which  are  fraudulent,  others  technical  in  nature.  Some  forms  of 
adulteration  are  injurious  to  health,  but  for  the  most  part  they  have 
an  economic  rather  than  a  sanitary  significance.  Foods  may  be  adul- 
terated in  a  variety  of  ways :  by  the  removal  of  nutritive  substances ; 
by  the  addition  of  injurious  substances;  by  the  fraudulent  substitution 
of  cheaper  articles ;  by  misbranding ;  or  by  the  sale  of  food  that  is  filthy, 
decomposed  or  putrid. 

Prior  to  the  passage  of  the  Pure  Food  and  Drugs  Act  in  1906  a  very 


524  GENERAL    CONSIDERATIONS 

large  percentage  of  the  food  .sold  in  the  United  States  was  found  to 
be  adulterated  in  one  way  or  another.  Thus,  at  the  Agricultural  Ex- 
periment Station  in  Kentucky  40  per  cent,  of  727  samples  were  adul- 
terated; at  the  Connecticut  Agricultural  Experiment  Station  41.5  per 
cent,  of  574  samples  of  spices  were  found  adulterated,  and  over  25  per 
cent,  of  coffee  samples  were  adulterated  (1899).^ 

Among  the  common  adulterations  may  be  mentioned  the  following: 
cotton-seed  oil  is  sold  as  olive  oil;  honey  may  contain  glucose;  cocoa 
and  chocolate  are  frequently  mixed  with  both  starch  and  sugar;  coffee 
is  extensively  adulterated  with  caramel,  pea-meal,  chickory,  and  sac- 
charose extracts;  lard  is  mixed  with  cheaper  fats  or  cotton-seed  oil; 
saccharin  is  substituted  for  cane  sugar;  cereals  give  bulk  and  weight  to 
sausages ;  gypsum  or  bran  is  added  to  flour ;  barium  sulphate  to  powdered 
sugar,  flour  or  turmeric  or  corn  meal  to  mustard.  Oleomargarin  is  sold 
as  butter;  distilled  and  colored  vinegar  is  sold  as  cider  vinegar;  ground 
spices  are  adulterated  with  cocoanut  shells,  rice,  flour,  and  ashes;  water, 
sugar,  and  tartaric  acid  is  sold  as  lemonade ;  wines  and  liquors  are  some- 
times adulterated  with  alum,  baryta,  caustic  lime,  salicylic  acid,  and 
hematoxylin.  Terra  alba,  kaolin,  and  various  pigments  are  sometimes 
added  to  candies;  gum  drops  are  largely  made  with  petroleum  paraffin 
products ;  much  of  the  maple  sugar  formerly  sold  was  made  from  glucose 
and  coloring  matters. 

A  food  is  considered  adulterated  in  accordance  with  the  Food  and 
Drugs  Act  of  June  30,  1906:  (1)  "If  any  substance  has  been  mixed 
and  packed  with  it  so  as  to  reduce  or  lower  or  injuriously  affect  its 
quality  or  strength."  This  is  the  simplest  form  of  adulteration,  and  a 
good  example  is  the  addition  of  water  to  milk.  Cocoa  shells  are  some- 
times mixed  with  cocoa  or  chocolate.  Glucose  and  caramel  are  added 
to  maple  sugar;  talc  to  flour. 

(2)  "If  any  substance  has  been  substituted  wholly  or  in  part  for  the 
article."  As  illustrations  we  have  the  substitution  of  cotton-seed  oil 
or  corn  oil  for  olive  oil;  glucose  or  saccharin  for  sugar;  cereals,  which 
cost  about  five  cents  a  pound,  for  meat,  which  averages  fifteen  cents  a 
pound,  in  sausage.  Apple  cores  and  parings  are  frequently  used  as  a 
substitute  for  currants  and  other  fruits  in  jellies. 

Saccharin  is  several  hundred  times  sweeter  than  sugar  and  compara- 
tively cheap.     It  has,  therefore,  been  used  as  a  substitute  for  sugar  as 

*In  Massachusetts  the  State  Board  of  Health  began  to  examine  foods  for 
adulteration  in  1883.  It  was  then  found  that  between  60  and  70  per  cent,  of  all 
foods  examined  were  adulterated.  As  a  result  of  official  surveillance  the  per- 
centages fell  in  a  few  years  to,  approximately,  1.5  per  cent,  and  have  remained 
between  10  and  20  per  cent,  since.  This  does  not  mean  that  from  10  to  20  per 
cent,  of  all  foods  found  on  the  market  are  adulterated,  for,  to  a  great  extent, 
samples  are  collected  from  suspicious  sources,  so  that  the  ratio  of  adulteration 
of  foods  analyzed  in  the  laboratory  is  higher  than  that  of  the  same  foods  sold 
on  the  market. 


ADULTERATION^  OF  FOOD  525 

a  sweetening  agent  in  the  inferior  qualities  of  ginger  ale,  and  to  some 
extent  in  canned  corn,  peas,  etc.,  as  well  as  in  candies  and  other  articles. 
Saccharin  is  a  chemical  obtained  from  coal  tar  and  is  without  food 
value;  it  is  not  entirely  harmless.  The  Eeferee  Board  reports  that 
"the  continued  use  of  saccharin  for  a  long  time  in  quantities  over  0.3 
of  a  gram  per  day  is  liable  to  impair  digestion;  and  the  addition  of 
saccharin  as  a  substitute  for  cane  sugar  reduces  the  food  value  of  the 
sweetened  product  and  hence  lowers  its  quality."  Saccharin-containing 
foods  are  therefore  regarded  as  adulterated  within  the  meaning  of  the 
Food  and  Drugs  Act. 

(3)  "If  any  valuable  constituent  of  the  article  has  been  wholly  or 
in  part  abstracted."  Skimming  milk  is  a  good  illustration  of  this  part 
of  the  law,  or  the  abstraction  of  cocoa  butter  from  chocolate.  There  is, 
however,  no  objection  to  abstracting  valuable  or  nutritive  substances 
provided  the  label  properly  announces  the  facts;  thus,  skimmed  milk 
or  cocoa  are  legitimate  foods.  So  also  the  caffein  may  be  taken  out  of 
coffee  and  sold  as  caffein-free  coffee.  The  essential  oils  are  sometimes 
extracted  from  cloves  or  other  spices,  which  are  subsequently  ground 
and  used  as  an  adulterant  with  unextracted  spice. 

(I)  "If  it  is  mixed,  colored,  powdered,  coated,  or  stained  in  any 
manner  whereby  damage  or  inferiority  is  concealed."  This  is  a  very 
frequent  form  of  adulteration,  and,  as  a  rule,  is  undesirable  and  some- 
times injurious.  Substances  used  to  color  foods  are  usually  considered 
in  three  classes:  (1)  mineral  dyes,  (2)  vegetable  dyes,  (3)  anilin  or 
coal-tar  dyes.  The  principal  mineral  dyes  are :  copper  sulphate,  oxid  of 
iron,  and  potassium  nitrate.  Copper  sulphate  is  used  to  give  a  green 
color  to  peas,  pickles,  and  similar  foods.  The  copper  probably  unites 
with  the  albuminous  matter  to  form  new  compounds  which  have  a 
bright  green  color.  The  oxid  of  iron  and  also  sulphites  are  used  upon 
meat  to  give  it  a  red  color;  potassium  nitrate  will  also  give  a  bright 
red  color  to  meat.  Many  vegetable  dyes  are  used,  such  as  annato  (the 
juice  of  the  Bixa  orellana,  a  South  American  tree),  which  is  used  to  color 
butter.  Carrot  juice  is  also  used;  turmeric  in  mustard;  and  logwood  in 
wines.  The  coal-tar  dyes  have  largely  replaced  the  vegetable  and  min- 
eral pigments  in  foods,  on  account  of  their  brilliant  color  and  cheap- 
ness. They  are  used  in  sausages,  confectionery,  jellies  and  jams,  meats, 
flavoring  extracts,  etc.  The  artificial  coloring  of  food  is  a  false  stand- 
ard and  serves  no  useful  purpose.  When  the  coloring  matter  is  used 
to  conceal  damage  or  inferiority  the  practice  is  indefensible,  as  when 
spoiled  meats  are  made  to  look  bright  red  and  fresh,  or  when  oleomar- 
garin  is  colored  in  order  to  imitate  butter  and  sold  as  such.  Flour 
may  be  bleached  with  nitrogen  peroxid,  thus  giving  an  inferior  grade 
the  appearance  of  first  quality  flour.  The  NO2  is  produced  by  electric 
action  and  nitrites  in  appreciable  quantities  remain  in  the  flour.    Fruits 


526  GENERAL    CONSIDERATIOXS 

are  bleached  by  exposure  to  sulphur  fumes,  which  leaves  objectionable 
sulphur  compounds.  Candies  and  chocolate  are  often  coated  with  gum 
benzoin  or  shellac. 

(5)  "If  it  contains  any  poisonous  or  other  added  deleterious  in- 
gredient which  may  render  such  article  injurious  to  health."  This 
section  of  the  law  is  intended  to  include  adulterants,  such  as  formal- 
dehyd,  sulphites,  arsenic,  hydrofluoric  acid,  lead,  salicylic  acid,  borax 
and  boracic  acid,  as  well  as  any  other  injurious  substance.  Most  of  the 
storm  center  of  the  opposition  to  the  Pure  Food  Law  is  centered  around 
this  paragraph,  owing  to  the  difficulty  of  deciding  in  certain  instances 
whether  small  amounts  of  benzoic  acid  or  benzoates,  boric  acid  or 
borates,  are  injurious  to  health  or  not.  These  substances  are  discussed 
more  in  detail  under  chemical  preservatives. 

(6)  "If.it  consists  in  whole  or  in  part  of  a  filthy,  decomposed,  or 
putrid  animal  or  vegetable  substance  or  any  portion  of  an  animal 
unfit  for  food,  whether  manufactured  or  not,  or  if  it  is  the  product  of 
a  diseased  animal  or  one  that  has  died  otherwise  than  by  slaughter." 
Examples :  oysters  contaminated  with  sewage ;  eggs  known  as  "rots  and 
spots";  animals  which  have  died  otherwise  than  by  slaughter;  figs  con- 
taining an  excessive  quantity  of  worms  and  worm  excrement.  This 
paragraph  of  the  law  has  caused  much  discussion,  especially  the  mean- 
ing of  the  word  "decomposed."  This  question  is  considered  more  in 
detail  under  the  paragraph  Decomposed  Foods. 

Misbranding. — The  term  "misbranding"  is  specifically  defined  in 
the  Food  and  Drugs  Act  and  provides  for  all  possible  conditions  of 
fraud,  mislabeling,  imitation,  substitution,  and  other  forms  of  decep- 
tion. Misbranding  is  regarded  as  a  form  of  adulteration  under  the 
Food  and  Drugs  Act.  The  practices  of  misbranding  under  any  cir- 
cumstances are  so  evidently  fraudulent  or  dislionest  that  they  cannot 
be  justified  on  any  score  and  are  wholly  condemned.  It  is  true  that 
many  instances  of  misbranding  do  not  directly  affect  health,  except  in 
so  far  as  they  deceive  the  consumer ;  that  is,  he  is  purchasing  at  a  high 
price  an  article  which  contains  less  nutritive  value  than  claimed  for  it. 
An  honest  label  which  correctly  states  the  character,  origin,  amount,  and 
the  constituent  parts  of  an  article  is  as  much  a  desideratum  in  food 
products  as  it  is  in  commercial  articles  of  all  kinds.  Honest  labeling  is 
the  heart  and  soul  of  the  pure  food  movement. 


DECOMPOSED    FOODS 

Decomposition  is  defined  as  natural  decay.  In  this  sense  all  or- 
ganic substances,  both  animal  and  vegetable,  living  or  dead,  are  decom- 
posed, for  decomposition  and  recomposition  occur  as  a  constant  feature 


DECOMPOSED    FOODS  527 

of  life's  processes.  At  the  moment  of  death  recomposition  ceases,  while 
decomposition  continues.  In  one  sense  the  hardest  rocks  decompose 
or  disintegrate;  bicarbonate  of  soda  decomposes  in  the  presence  of  an 
acid,  and  many  substances  decompose  in  the  presence  of  oxygen,  es- 
pecially when  heated.  In  other  words,  while  decomposition  is  usually 
the  result  of  bacterial  activity  in  organic  substances,  it  may  also  take 
place  as  the  result  of  physical,  chemical,  or  electrical  agencies.  The 
word  "decomposition"  is  not  used  in  this  technical  sense  in  the  Pure 
Food  and  Drugs  Act;  there  it  has  the  meaning  of  the  word  used  in 
ordinary,  every-day  parlance.  Just  where  technical  decomposition  ceases 
and  objectionable  decomposition  begins  is  often  difficult  to  determine. 
Decomposition  may  be  objectionable  either  to  the  senses  or  to  health. 
We  purposely  permit  many  of  our  foods  to  decompose  before  they  are 
used.  Thus,  meats  hang  three  days  or  longer  in  order  to  render  them 
more  tender  and  to  improve  their  flavors.  During  this  time  decom- 
position takes  place  with  the  production  of  acids.  Some  persons  prefer 
meats  when  highly  decomposed  or  gamy.  Bread,  cheese,  butter,  butter- 
milk, sauerkraut,  vinegar,  cider,  and  many  other  foods  are  products 
of  decomposition.  The  line  must,  therefore,  be  drawn  between  decom- 
position that  is  objectionable  and  decomposition  that  is  technical.  It  is 
difficult  to  draw  the  line  at  decomposition  that  is  objectionable  to  the 
senses,  for  a  cheese  regarded  as  a  delicacy  by  one  person  may  be  highly 
objectionable  to  another.  The  principal  point,  then,  for  consideration 
is  the  decomposition  that  is  harmful  to  health. 

Fermentation  and  Putrefaction. — The  question  is  further  compli- 
cated when  we  consider  that  there  are  very  many  kinds  of  decomposi- 
tion. Two  main  groups  are  recognized:  (1)  fermentative  decomposi- 
tion, and  (2)  putrefactive  decomposition.  Even  the  Pure  Food  Law 
distinguishes  between  foods  that  are  decomposed  and  foods  that  are 
putrid.  Fermentative  decomposition  refers  to  the  breaking  down  of 
carbohydrates  with  the  formation  of  acids  (lactic,  acetic,  butyric),  alco- 
hol, carbon  dioxid,  etc.  Putrefactive  decomposition  refers  to  the  breaking 
down  of  nitrogenous  substances,  usually  with  the  production  of  alkalinity. 
The  end  products  of  putrefaction  are  ammonia,  nitrates,  carbon  dioxid, 
etc.,  all  simple,  stable,  inorganic  compounds  which,  in  ordinary  concen- 
tration, are  not  poisonous.  It  is  then  the  intermediate  cleavage  products 
of  putrefaction  and  the  end  products  of  fermentation  that  may  be  poison- 
ous. The  question  of  decomposition  is  still  further  complicated  by  the 
fact  that  there  are  very  many  different  kinds  of  fermentation  and  of 
putrefaction.  Each  particular  microorganism  breaks  down  organic  mat- 
ter in  a  specific  and  limited  sense.  Ordinarily  these  processes  result 
from  a  combination  of  bacteria  or  symbiosis,  in  which  aerobic  and  anaero- 
bic organisms  each  play  a  part.  As  a  rule,  putrefaction  does  not  take 
place  in  the  presence  of  fermentation.    In  this  sense  carbohydrates  pro- 


528  GENERAL    CONSIDERATIOISrS 

tect  nitrogenous  matter;  further,  the  products  of  fermentation  are  much 
less  poisonous  tlian  some  of  the  products  of  putrefaction. 

"Ptomain"  Poisoning. — Ptomains  are  secondary  cleavage  products 
of  protein  putrefaction.  Yaughaii  defines  a  ptomain  as  an  organic 
chemical  compound,  basic  in  character,  and  formed  by  the  action  of 
bacteria  on  nitrogenous  matter.  On  account  of  their  basic  properties 
ptomains  resemble  the  vegetable  alkaloids  and  are,  therefore,  called 
putrefactive  alkaloids.  They  are  sometimes  called  "animal"  alkaloids, 
but  this  is  a  misnomer,  for  they  also  are  formed  in  the  putrefaction  of 
vegetable  matter. 

The  term  "leukomain"  is  used  to  cover  the  same  or  similar  basic 
substances  which  result  from  tissue  metabolism  within  the  body;  that 
is,  leukomains  are  produced  in  the  living  body,  ptomains  in  dead  or- 
ganic matter. 

The  great  majority  of  ptomains  are  not  poisonous  or  less  toxic 
than  the  corresponding  ammonia  compound.  Ptomains  include  sub- 
stances which  are  chemically  very  different.  The  classification  is  not 
a  scientific  one,  and  is  gradually  being  abandoned.  In  fact,  most  cases 
of  so-called  ptomain  poisoning  are  really  infections  with  microorganisms 
belonging  to  the  paratyphoid  group. 

The  products  produced  during  the  various  stages  of  protein  putre- 
faction resemble  the  chemical  products  produced  during  the  stages  of 
protein  digestion.  Putrid,  or  putrefying,  organic  matter  is  not  neces- 
sarily poisonous  or  even  harmful.  There  is  a  time  when  decomposing 
meat  or  cheese  or  other  nitrogenous  substance  reaches  the  height  of  its 
toxicity,  then  gradually  declines,  and  finally  becomes  inactive.  The 
terminal  products  of  putrefaction,  or  even  the  later  stages,  while  they 
may  be  highly  offensive  to  the  taste  and  smell,  may  be  quite  harmless. 
Therefore,  cheese,  if  toxic,  is  most  poisonous  when  green;  that  is,  dur- 
ing the  intermediate  stages.  Meat,  if  toxic,  is  most  poisonous  from 
the  fourth  to  the  eleventh  day  of  putrefaction.  The  poisonous  prop- 
erties of  other  foodstuffs  have  a  similar  relation  to  the  stage  of  putre- 
faction.^ 

Chemically,  ptomains  are  ammonia  substitution  compounds;  two- 
thirds  of  them  contain  only  carbon,  hydrogen,  and  nitrogen.  Those 
having  oxygen  in  their  composition  are  the  more  poisonous.  Most 
ptomains  are  inert  or  are  no  more  poisonous  than  the  corresponding 
ammonia  salts.  In  composition  they  show  a  predominance  of  the 
amin  radicle  (NHg).  Of  the  bases  containing  oxygen,  most  of  them 
are  trimethylamins  [(CII,)3jSr].  It  was  Brieger  who  pointed  out  that 
a  certain  quantity  of  oxygen  is  necessary  for  the  formation  of  poison- 

^It  seems  that  advanced  decomposition  favors  the  destruction  of  the  poison- 
ous substances  formed  earlier  in  the  process;  it  is  further  known  that  most  of 
the  pathologic  microorganisms  die  during  active  fermentative  or  putrefactive 
changes. 


DECOMPOSED    FOODS  529 

ous  bases.  These  poisonous  bases  appear  about  the  seventh  day  of 
putrefaction  and  then  disappear. 

The  decomposition  products  of  putrefaction  have  long  been  studied 
by  chemists.  All  the  studies  made  before  bacterial  activity  was  under- 
stood are  now  only  of  historical  interest.  The  distinguished  physician, 
Panum,  was  the  first  to  demonstrate  positively  the  chemical  nature  of 
the  poisons  formed  in  putrid  flesh.  He  obtained  an  aqueous  extract 
which  retained  its  poisonous  properties  after  boiling  eleven  hours. 
Panum  studied  these  poisonous  substances  by  intravenous  injections 
upon  dogs.  These  observations  have  been  abundantly  confirmed,  but 
so  far  it  is  doubtful  whether  anyone  has  succeeded  in  isolating  the 
poisonous  substances  in  a  pure  state. 

In  1886  Bergmann  and  Schmiedeberg  obtained  sepsin  from  putrid 
flesh  and  from  decomposing  bodies.  This  substance  was  obtained  in 
needle-shaped  crystals,  and  small  doses  injected  into  dogs  caused  vom- 
iting and  bloody  diarrhea.  It  was  then  believed  that  the  putrid  poison 
of  Panum  had  been  isolated  and  was  identical  with  sepsin.  Further 
investigation,  however,  showed  that  this  was  not  the  fact.  Selmi,  an 
Italian,  added  valuable  information  to  the  study  of  this  question,  and, 
what  is  probably  more  important,  gave  an  impetus  to  the  study  of  the 
chemistry  of  putrefactive  changes.  Selmi  was  the  first  to  suggest  the 
name  ptomain;  he  showed  that  there  are  a  great  number  of  alkaloid- 
like substances  among  the  products  of  putrefaction.  Some  of  these 
may  be  extracted  with  ether  from  an  alkaline  solution,  some  with  ether 
from  an  acid  solution,  some  with  chloroform  from  either  an  acid  or 
alkaline  solution,  and  some  with  amylic  alcohol,  and  after  all  these 
extractions  there  yet  remain  alkaloidal  bodies  in  the  putrid  infusion. 
This  gives  us  an  indication  of  the  great  number  of  ptomains.  We  long 
remained  ignorant  of  the  chemistry  of  these  substances  until  Nencki 
in  1876  made  the  first  ultimate  analysis  and  determined  the  empiric 
formula  for  ptomains.  In  1871  Lombroso  showed  that  an  extract  from 
moldy  corn  produced  tetanic  convulsions  in  animals.  This  observation 
was  part  of  Lombroso's  long  struggle  to  discover  the  chemical  substance 
responsible  for  pellagra.  In  1885  Vaughan  detected  in  poisonous  cheese 
an  active  agent  to  which  he  gave  the  name  tyrotoxicon.  However, 
Vaughan  afterward  admitted  that  this  is  not  the  substance  most  com- 
monly fo^md  in  poisonous  cheese,  though  the  names  tyrotoxicon  poison- 
ing and  ptomain  poisoning  remain  in  popular  parlance.  Brieger  kept 
the  name  ptomain,  but  applied  it  to  those  basic  substances  only  that 
were  produced  in  the  life  processes  of  bacteria.  He  classed  under  the 
head  of  ptomains  a  great  number  of  poisons  which  he  succeeded  in 
isolating  from  putrid  flesh,  decomposed  fish,  rotten  cheese,  decomposed 
glue,  cadavers  in  various  stages  of  decomposition,  from  poisonous  mus- 
sels, etc.     Since  these  a  long  list  of  basic  substances  or  ptomains  have 


530  GENERAL    CONSIDERATIONS 

been  described.^  As  before  pointed  out,  the  great  majority  of  them 
are  not  poisonous,  or  slightly  so.  The  list  includes  a  variety  of  sub- 
stances which  are  chemically  very  different.  The  classification  is  not 
a  scientific  one,  and  is  gradually  being  abandoned.  Even  at  the  time 
of  Brieger's  investigations  it  was  found  necessary  to  distinguish  be- 
tween poisonous  and  non-poisonous  ptomainsj  and  on  this  account  the 
term  toxine  was  adopted.  Finally  it  must  clearly  be  kept  in  mind  that 
even  the  poisonous  "ptomaines"  are  toxic  when  injected  into  animals, 
but  for  the  most  part  not  when  taken  by  the  mouth. 

The  best  known  poison  which  has  been  isolated  in  an  approximately 
pure  state  from  decomposing  nitrogenous  material  is  sepsin.  Much 
work  has  been  done  upon  this  substance  by  Schmiedeberg  and  recently 
by  Faust,  who  obtained  sepsin  in  a  purified  state  in  sufficient  quan- 
tities carefully  to  study  its  action  and  composition.  Faust  ob- 
tained the  crystals  from  putrefied  yeast  and  blood;  25  milligrams  of 
the  sulphate  introduced  intravenously  will  kill  a  large  dog  in  two 
hours. 

Sepsin  has  the  following  chemical  structure : 

NH2  OH     OH     NH2 

I  I  I         I 

CH— CH3— CH— CH— CH2 

Di-hydroxy-penta-methylene-diamin. 

Sepsin  is  very  unstable.  It  is  rendered  inactive  at  60°  C.  for  a 
short  time,  and  is  readily  converted  into  cadaverin  or  pentamethylene- 
diamin.    The  chemical  structure  of  cadaverin  is : 

NH2  NH2 

I  I 

CHg — CHg — CHo — CH2 — CHg 

Penta-methylene-diamin. 

Cadaverin  is  one  of  the  best  known  of  the  ptomain  group.  Its 
presence  indicates  that  the  putrefactive  process  at  one  time  contained 
gepsin  which,  by  reduction,  has  been  changed  into  cadaverin. 

Putrescin  is  another  diamin,  which  almost  invariably  occurs  together 
with  cadaverin,  to  which  it  is  closely  related.  It  was  first  described 
by  ■  Brieger  in  1885,  and  has  been  obtained  from  putrefying  internal 
human  organs,  herring,  mussels,  etc.  It  is  recognizable  on  the  fourth 
day  of  putrefaction,  and  appreciable  quantities  appear  by  the  eleventh 
day.  It  is  still  present  after  two  or  three  weeks,  Baummann  in  1888 
showed  the  rational  formula  to  be : — 

*See  Vaugfhan  and  Novy:     "Cellular  Tpxips," 


PEESERVATION   OF   FOODS  531 

NH2  NH2 

I  I 

CH2— CH2— CH,— CH2 

Tetra-methylene-diamin. 

Putrescin  is  a  homolog  of  cadaverin  and  appears  in  putrefaction 
before  that  substance. 

The  more  the  question  of  ptomains  is  studied  the  less  do  they  ap- 
pear concerned  in  cases  of  food  poisons.  It  is  now  clear  that  most,  if 
not  all,  cases  of  so-called  ptomain  poisoning  are  nothing  more  nor  less 
than  acute  infections  with  B.  paratypliosus,  B.  enteritidis,  B.  cholerae 
suis,  and  other  microorganisms  belonging  to  this  group.  A  number 
of  bacteria  ordinarily  harmless  are  capable,  under  certain  conditions, 
or  in  overwhelming  numbers,  of  producing  acute  gastrointestinal  dis- 
turbances. Some  of  these  microorganisms  and  their  effects  are  discussed 
more  particularly  under  Meat  Poisoning. 

Less  is  known  concerning  the  decomposition  of  the  fats.  It  is  quite 
possible  that  some  of  these  substances  may  be  exceedingly  poisonous. 
Thus,  while  cholin  in  itself  is  not  very  toxic,  Hunt  has  shown  that 
acetyl-cholin  is  one  hundred  thousand  times  more  poisonous.  Cholin 
is  a  base  widely  distributed  in  nature;  it  is  found  in  the  yolk  of  eggs, 
in  bile,  brain  substance,  fat,  seeds,  and  other  substances.  It  can  also 
be  prepared  from  pure  lecithin,  which  is  a  fatty  body  normally  pres- 
ent in  brain  substance,  yolk  of  eggs,  and  perhaps  all  cells.  The  lecithin 
may  be  readily  decomposed  by  bacterial  action  perhaps  to  cholin  and 
cholin  salts.  While  acetyl-cholin  has  never  been  demonstrated  in  food, 
it  is  possible  that  this  or  similar  poisons  may  be  produced  in  decom- 
posing foodstuffs. 

PRESERVATION  OF   FOODS 

The  preservation  of  meat,  milk,  vegetables,  and  other  perishable 
foods  is  one  of  the  most  important  questions  we  have  to  deal  with  in 
the '  whole  range  of  hygiene.  Fermented  and  decayed  foods  must  be 
looked  upon  with  suspicion.  The  proper  preservation  of  foodstuffs 
involves  not  only  the  art  of  keeping  them  "fresh"  and  wholesome,  but 
also  keeping  them  so. that  they  will  not  lose  their  nutritive  value.  Fi- 
nally, foodstuffs  must  be  preserved  so  that  they  will  not  acquire  injurious 
properties.  The  preservatives  ordinarily  in  use  are :  cold,  drying,  salt- 
ing, smoking,  canning,  preserving,  and  chemical  treatment. 

Practically  all  these  methods  have  long  been  in  use.  The  only 
modern  innovation  in  the  preservation  of  foods  is  in  the  perfection  of 
the  old  processes,  based  upon  our  knowledge  of  antiseptics  and  germi- 
cides.    Heat  and  cold  represent  old  family  methods  which  have  been 


532  GENEEAL    CONSIDERATIONS 

extended  and  improved  in  the  modern  cajiniiig  and  cold  storage  indus- 
tries. The  drying  of  fruits,  fish,  and  meats  is  a  practice  of  very  ancient 
origin.  The  use  of  salt  doubtless  antedates  all  historical  records.  Sugar 
either  alone  or  with  acetic  acid  in  the  form  of  vinegar  and  with  vari- 
ous spices  is  an  old  contrivance  and  well  known  everywhere.  The  ap- 
plication of  creosote  obtained  crudely  from  the  smoke  of  incompletely 
burned  wood  is  the  ancient  forerunner  of  some  of  the  modern  packing 
processes. 

Concerning  the  value  and  legitimacy  of  these  old  family  methods 
there  is  comparatively  little  difference  of  opinion;  salt  meat  is  not  as 
good  as  the  fresh  article;  dry  apples  do  not  make  the  best  apple  pie; 
chipped  beef  is  not  an  adequate  substitute  for  a  fresh  steak.  However, 
it  is  absolutely  necessary  to  preserve  food  in  some  way  in  order  to 
tide  over  the  winter  or  the  dry  seasons,  to  furnish  food  to  people  living 
and  working  in  desert  and  arid  regions,  and  to  feed  the  hordes  of  peo- 
ple massed  together  in  great  cities.  It  would  be  impossible  to  main- 
tain the  large  population  of  a  modern  metropolis  if  it  were  dependent 
upon  a  daily  supply  of  fresh  food  materials. 

The  art  of  preserving  foods  depends  upon  the  science  of  bacteriol- 
ogy. A  more  complete  knowledge  of  the  causes  of  decomposition  and 
methods  by  which  they  may  be  prevented  has  enabled  us  to  perfect 
the  crude  and  primitive  methods  that  have  been  in  use  from  time  im- 
memorial, so  that  it  is  now  possible  to  preserve  certain  foods  practi- 
cally indefinitely  without  in  any  way  injuring  their  nutritive  value  or 
seriously  interfering  with  their  appearance  and  taste. 

The  chief  harm  has  come  from  the  blind  use  of  chemical  germi- 
cides, without  regard  for  their  harmful  properties.  The  simplest  and 
cheapest  way  to  preserve  food  is  by  adding  one  of  these  chemicals,  and 
the  method  was,  therefore,  seized  upon  by  alert  men  whose  chief  in- 
terest was  of  the  pecuniary  kind.  The  question  was  to  find  the  small- 
est percentage  of  a  chemical  which  would  prevent  the  decay  of  some 
particular  food  product,  trusting  to  luck  that  the  preservative  used 
might  prove  harmless  to  the  consumer.  Often  these  chemicals  were 
added  with  a  liberal  hand;  further,  it  was  soon  found  that  chemical 
preservatives  could  be  used  to  preserve  food  products  for  the  market 
from  materials  already  so  decayed  as  to  be  unsalable  in  their  original 
condition. 

The  National  Pure  Food  and  Drugs  Act  of  1906  was  passed  largely 
to  meet  this  situation.  This  law  considers  any  food  which  contains 
some  "added  poisons  or  other  deleterious  ingredient  which  may  render 
such  article  injurious  to  health"  as  adulterated.  To  Harvey  W.  Wiley 
belongs  the  credit  of  inducing  Congress  to  pass  this  legislation  against 
opposition  and  for  an  aggressive  administration  that  proved  useful  in 
bringing  the  whole  question  prominently  before  the  public. 


PEESERVATION  OF  FOODS  533 

Cold. — Cold  must  be  regarded  by  the  sanitarian  as  an  antiseptic 
rather  than  a  germicide.  Low  temperatures  kill  few  bacteria,  but  pre- 
vent the  growth  and  multiplication  of  most  of  them.  Even  the  anti- 
septic properties  of  cold  are  not  as  marked  as  they  were  once  believed 
to  have  been.     Many  plants  and  even  frogs  may  survive  freezing. 

Some  bacteria  grow  and  multiply  at  low  temperatures,  even  at  0°  C. 
In  1871  Burdon-Sanderson  was  the  first  to  show  that  freezing  does  not 
kill  bacteria.  Von  Frisch  demonstrated  that  subjecting  a  putrefying 
solution  to  a  temperature  of  — 87°  C.  for  some  hours  did  not  effect 
sterilization.  Leidy  in  1848  showed  that  water  derived  from  melted 
ice  contained  not  only  living  infusoria,  but  also  rotifers  and  worms. 
Pictet  and  Young  found  that  anthrax  and  symptomatic  anthrax  cul- 
tures were  not  killed  after  an  exposure  of  108  hours  to  — 70°  C.  Later 
Macfadyen  proved  that  the  temperature  of  liquid  air  does  not  kill  bac- 
teria; he  subjected  cultures  to  temperatures  of  — 315°  F.  Ehrlich  has 
recently  shown  that  cancer  cells  kept  cold  will  live  and  remain  virulent 
for  at  least  two  years. 

While  no  microorganism  pathogenic  for  man  will  grow  and  multiply 
at  the  low  temperatures  of  the  refrigerator,  there  are  a  number  of 
saprophytic  bacteria  and  molds  that  develop  abundantly  at  tempera- 
tures as  low  as  0°  C.  Milk,  meat,  eggs,  and  other  products  kept  in 
cold  storage  at  or  near  the  freezing  point  may  show  a  notable  increase 
in  the  number  of  bacteria.  A  number  of  tests  made  in  my  laboratory 
showed  that  in  the  case  of  milk  these  low-temperature  microorganisms 
belong  mainly  to  the  putrefying  and  proteolytic  group.  They  produce 
an  alkaline  reaction  in  the  milk  and  a  bitter  taste.  Whether  they  are 
capable  of  forming  poisonous  products  at  these  low  temperatures  is 
doubtful. 

For  the  most  part  pathogenic  bacteria  withstand  freezing  tempera- 
tures. They,  however,  suffer  a  quantitative  reduction  when  frozen  (see 
Ice  and  the  effects  of  freezing  upon  bacteria,  page  948).  Most  animal 
parasites  die  in  cold  storage ;  a  few,  however,  survive.  The  time  in  which 
the  material  has  been  refrigerated  is  an  important  factor.  Just  as 
infected  water  becomes  safer  by  storing  it,  so  with  foods,  but  cold  storage 
foods,  while  safer,  cannot  be  entirely  relied  upon  for  all  infections. 
Trichinae  die  at  or  below  5°  C.  in  twenty  days.  Taenia  saginata,  the  beef 
tapeworm,  dies  in  twenty-one  days,  but  Taenia  solium,  the  pork  tape- 
worm, may  live  more  than  twenty-nine  days  in  cold  storage. 

Fortunately,  cold  causes  a  quantitative  reduction  in  the  number  of 
harmful  bacteria,  even  though  it  does  not  produce  complete  steriliza- 
tion. The  element  of  time  here  plays  an  important  role,  as  most  of 
the  surviving  pathogenic  microorganisms  soon  die.  From  a  sanitary 
standpoint  the  protection  afforded  by  refrigeration  is  reassuring,  although 
not  perfect.    Cold  acts  as  a  preservative  for  some  viruses. 


534  GENERAL    CONSIDERATIONS 

The  best  temperature  at  which  foodstuffs  may  be  kept  must  be  de- 
termined for  each  case.  Some  substances,  such  as  meat  and  poultry, 
are  better  preserved  when  actually  frozen;  others,  such  as  shell-eggs  or 
milk,  are  materially  injured  by  freezing.  Fish  are  usually  frozen.  They 
are  then  dipped  in  water  and  re-frozen  in  order  that  they  may  be  com- 
pletely encased  in  ice.  They  are  then  stored  at  a  temperature  of  — 16°  C. 
The  coating  of  ice  which  is  renewed  as  occasion  requires,  prevents  loss 
of  water  due  to  surface  evaporation.  Under  these  circumstances  there  is 
no  evidence  whatever  of  any  depreciation  in  the  nutritive  value  or  any 
change  in  the  sanitary  character  of  the  fish  at  any  time  during  two  years 
of  cold  storage.^ 

In  any  event,  the  temperature  of  the  icebox  should  not  rise  above  7° 
C.  At  this  temperature  bacterial  growth  does  not  entirely  cease,  although 
very  markedly  hindered.  Few  household  refrigerators  reach  this  tem- 
perature or  maintain  it  for  any  length  of  time — either  through  faulty 
construction  or  on  account  of  insufficient  ice.  Often  the  icebox  is  placed 
in  a  sunny  corner,  or,  for  convenience,  near  the  kitchen  stove.  The  doors 
of  the  ice  chest  frequently  do  not  fit  well,  which  results  in  needless  waste 
and  imperfect  refrigeration.  A  study  of  household  refrigerators  dis- 
closes the  fact  that  the  temperature  is  often  15°  C.  and  higher.  Such 
conditions  make  good  incubators,  favoring  bacterial  growth.  The  ne- 
cessity for  scrupulous  cleanliness,  aeration,  and  dryness  in  all  refriger- 
ating devices  needs  only  be  mentioned. 

In  ordinary  refrigerating  plants  moisture  condenses  on  the  surface 
of  the  objects  exposed.  In  the  case  of  meat  this  moisture  dissolves 
some  of  the  proteins,  extractives,  and  salts,  and  makes  a  perfect  cul- 
ture medium  for  bacteria  and  molds.  In  the  case  of  meats  it  is,  there- 
fore, better  to  hang  them  in  a  current  of  dry,  clean  air,  in  order  to 
desiccate  the  surface,  before  they  are  placed  in  the  refrigerator.  The 
dried  surface  delays  the  inward  growth  of  the  inevitable  bacterial  con- 
tamination upon  the  surface. 

Articles  of  food  may  be  kept  in  a  satisfactory  condition  in  cold 
storage  for  a  very  long  time.  The  time  varies  with  the  article  and 
its  condition  when  placed  in  storage,  also  with  the  temperature  and 
other  factors.  A  striking  illustration  of  the  great  preserving  power 
of  low  temperatures  occurred  several  years  ago  in  Northern  Siberia. 
In  consequence  of  a  great  landslide  on  the  banks  of  the  Kolyma,  the 
head  of  a  mammoth  became  exposed  and  was  so  well  preserved  that 
even  the  fleshy  trunk  remained.  It  is  said  that  famished  wolves  and 
half-starved  natives  began  to  eat  of  the  flesh.  The  Russian  government 
sent  Dr.  Hertz  to  rescue  what  remained.  The  mammoth  had  re- 
mained in  cold  storage  perhaps  thousands  of  years.  Some  of  the  soft 
parts  are  now  preserved  in  the  Museum  at  Petrograd.  This  must  not 
*  Smith,  C.  S.:     Biochem.  Bull,  1913,  III,  54. 


PEESEEVATIOX   OF  FOODS  535 

be  taken  as  justification  of  prolonged  storage  or  the  "cornering"  of 
foods  for  economic  gain  in  mammoth  cold  storage  warehouses.  While 
meat,  poultry,  eggs,  and  vegetables  may  be  kept  in  a  satisfactory 
condition  for  months  and  transported  over  seas,  cold  storage  need  not 
be  unduly  prolonged.  In  any  case,  the  consumer  is  entitled  to  know 
whether  the  article  is  fresh  or  stored,  and  the  time  it  has  been  in  cold 
storage.    These  facts  should  be  stated  upon  the  label  or  stamp. 

During  the  past  few  years  cases  of  so-called  "ptomain"  poisoning 
have  been  attributed  to  the  ingestion  of  cold  storage  poultry.  It  is 
supposed  that  the  undrawn  condition  stimulates  decomposition  during 
cold  storage.  Laws  have,  therefore,  been  passed  in  certain  states  re- 
quiring poultry  to  be  drawn  before  being  placed  in  cold  storage.  It  is 
claimed,  on  the  other  hand,  that  the  undraM^n  fowl  keep  better — it  is 
certain  that  they  weigh  more,  which  is  an  advantage  to  the  dealer.  The 
disadvantage  of  drawing  fowl  by  the  ordinary  method  is  that  the  car- 
cass becomes  contaminated  with  the  intestinal  contents  and  putrefactive 
processes  are  hastened.  This  question  was  investigated  by  the  Massa- 
chusetts State  Board  of  Health,  and  the  conclusion  was  reached  that 
it  made  practically  no  difference  whether  the  fowl  were  drawn  or  not, 
but  that  they  must  be  perfectly  fresh  when  placed  in  cold  storage. 
Poultry  is  kept  below  0°  C,  at  which  temperature  no  noticeable  change 
occurs.  It  was  found  that  cold  storage  fowl  are  even  less  contaminated 
with  bacteria  than  freshly  killed  birds  that  have  hung  for  a  few  days. 
However,  the  cold  storage  animals,  when  removed  from  the  refrigera- 
tor, decompose  more  quickly  than  the  fresh. 

Contrary  to  v/hat  might  be  expected,  drawn  poultry  decomposes 
more  rapidly  after  removal  from  cold  storage  than  undrawn.  This  is 
because  in  the  process  of  drawing  the  intestines  are  broken  below  the 
gizzard  and  the  carcass  becomes  badly  contaminated  with  intestinal 
bacteria.  If  the  entire  alimentary  canal,  esophagus,  crop,  gizzard,  and 
intestines  are  removed  intact,  and  with  due  care  to  prevent  bacterial 
contamination,  the  bird  is  practically  safe  from  putrefaction.  In  case, 
therefore,  poultry  is  drawn  before  it  is  placed  in  cold  storage,  the  draw- 
ing should  be  done  with  bacteriological  care. 

From  a  sanitary  standpoint,  then,  refrigeration  is  one  of  the  best 
methods  of  preserving  foodstuffs.  The  advantages  of  cold  as  a  preserva- 
tive are  that  it  neither  adds  any  constituent  to  the  food  nor  takes  away 
any  constituent  from  the  food.  Cold  imparts  no  new  taste,  nor  does  it 
seriously  alter  the  natural  flavor.  It  does  not  diminish  its  digestibility 
nor  cause  a  loss  of  nutritive  value.  The  material  is  left  in  approxi- 
mately its  original  condition.  Cold  may,  therefore,  be  regarded  as 
one  of  the  simplest  and  best  antiseptics  we  have  for  the  preservation 
of  foods.  It  is  now  almost  universally  applied  to  prevent  decomposition 
and  decay.     The  housewife  uses  it  to  keep  food  in  cold  cellars,  deep 


536  GENERAL    CONSIDERATIONS 

wells,  and  the  like.  During  the  last  fifty  years  the  use  of  ice  for  the 
purpose  of  refrigeration  has  become  commonplace.  Fresh  and  whole- 
some food  may  now  be  transported  to  the  tropics,  and  the  sustenance 
of  large  communities  in  insular  and  arid  regions  is  made  possible  and 
pleasurable  through  the  preserving  use  of  cold. 

Drying. — Drying,  desiccation,  or  evaporation  is  a  favorite  and  primi- 
tive method  of  preserving  meats,  fruits,  vegetables,  and  various  food 
materials.  Dryness  furnishes  ideal  antiseptic  conditions.  Microorgan- 
isms must  have  moisture  to  grow  and  multiply.  Most  pathogenic  micro- 
organisms soon  die  when  dried,  hence  the  process  has  a  decided  sani- 
tary advantage.  Further,  dried  fruits,  vegetables  or  meats  are  rarely 
eaten  raw,  and  the  cooking  is  a  further  sanitary  safeguard. 

The  effectiveness  of  drying  as  a  food  preservative  depends  upon 
the  thoroughness  with  which  the  process  is  carried  out.  It  is  not  so 
well  adapted  to  meats  as  to  vegetables  and  fruits.  Dried  meats  lose 
their  natural  flavor,  which  may  be  replaced  with  others  less  real.  All 
sorts  of  organic  foodstuffs,  even  the  most  decomposable,  such  as  milk, 
eggs,  or  meat,  may  be  dried  and,  if  kept  dry,  they  will  keep  in  a  satisfac- 
tory state  almost  without  limit  of  time. 

Theoretically  dryness  is  not  a  complete  safeguard,  for  the  reason 
that  a  few  microorganisms  survive,  particularly  bacterial  spores.  Despite 
this  slight  limitation,  it  is  more  than  reasonably  safe  and  an  entirely 
satisfactory  procedure.  Practically  the  only  change  in  dried  foods 
is  the  loss  of  moisture,  which  may  readily  again  be  supplied.  Dryness 
has  the  great  advantage  in 'that  no  added  chemical  or  added  preserva- 
tive process  is  necessary;  further,  dried  foods  are  quite  as  nutritious 
and  usually  quite  as  digestible  as  the  fresh  articles,  although  not  quite 
as  savory. 

Dried  Meat. — In  the  dry  climates  of  South  America  and  on  cur 
western  plains  meat  is  cut  into  thin  strips,  suspended  in  the  air, 
and  exposed  to  direct  sunlight.  In  a  short  time  the  moisture  disap- 
pears and  the  hard  dry  pieces  keep  indefinitely,  ot  as  long  as  they  are 
kept  dry.  The  meat  retains  a  fair  degree  of  palatability  and  practi- 
cally all  of  its  nutrient  properties.    This  is  known  as  jerked  beef. 

Dried  beef  is  also  prepared  by  first  treating  the  meat  with  condi- 
ments and  then  drying  it  artificially.  Chipped  beef  or  dried  beef  is 
prepared  in  this  manner,  except  that  the  meats  are  often  smoked  as  well 
as  salted  and  desiccated,  so  that  in  their  method  of  preparation  more 
than  one  method  of  preservation  is  employed. 

Powdered  meats  are  prepared  by  complete  desiccation,  and  such 
products  are  found  upon  the  market  as  a  finely  ground  powder.  Meat 
powders  are  made  not  alone  from  fresh  meats  in  their  natural  state, 
but  are  also  prepared  after  more  or  less  artificial  digestion. 

Dried  Fruits. — Dried  apples  are  taken  as  a  type  of  dried  fruits 


PEESERVATIOJ^   OF  FOODS  537 

and  vegetables.  The  apples  may  be  dried  naturally  by  cutting  them 
into  convenient  sizes  and  exposing  them  to  the  action  of  the  sun.  This 
is  more  a  domestic  than  a  commercial  industry.  When  apples  are 
dried  by  this  simple  process  they  darken  and  become  unattractive  in 
appearance.  This  is  due  to  the  oxidizing  action  of  the  enzymes  when 
exposed  to  the  air.  When  properly  prepared  the  dried  apple  has  its 
moisture  content  reduced  to  approximately  30  per  cent,  or  less. 

In  order  to  prevent  the  darkening  of  the  surface  during  the  long 
exposure  necessary  to  secure  the  proper  degree  of  evaporation^  apples 
are  usually  subjected  to  the  fumes  of  burning  sulphur.  The  sulphur 
dioxid  acts  as  a  bleaching  agent  and  the  sulphurous  and  sulphuric 
acids  retained  in  the  apple  act  as  preservatives.  Apples  treated  with 
sulphur  fumes  are  less  likely  to  decay  or  become  infected  with  molds 
than  a  similar  product  not  exposed  to  sulphur  fumes.  The  process 
is  objected  to  from  the  standpoint  of  health,  for  the  reason  that  the 
sulphurous  acids  and  sulphites  are  admittedly  injurious  to  health.  The 
Department  of  Agriculture  found  that  approximately  half  of  the  evapo- 
rated fruits  purchased  on  the  open  market  had  been  treated  with  sul- 
phur fumes.  In  order  to  obtain  a  satisfactory  dried  product  it  is  of 
some  importance  that  the  fruits  be  selected,  so  as  to  reject  all  imper- 
fect, rotten,  or  infected  specimens. 

Evaporated  apples  is  a  term  applied  to  apples  dried  artificially  in- 
stead of  being  exposed  to  the  sun's  heat.  The  process  is  rapid  and 
satisfactory,  and  has  no  sanitary  objections. 

Dkied  Eggs. — Eggs  are  broken  out,  mixed  and  dried  by  spreading 
the  mass  in  a  thin  film  in  shallow  pans  or  upon  a  broad  revolving  belt ; 
the  water  is  abstracted  by  exposure  to  a  current  of  warm  dry  air.  The 
egg  substance  may  also  be  dried  by  forcing  it  through  small  orifices 
under  a  high  pressure  into  a  drying  chamber  so  adjusted  as  to  tempera- 
ture and  size  as  to  secure  the  desiccation  of  the  minute  particles  of  egg 
spray  before  they  fall  to  the  bottom.  Egg  substance  thoroughly  dried 
keeps  satisfactory  in  almost  any  climate.  It  retains  all  the  nutritive 
value  in  the  original  egg. 

Dried  Milk. — Milk  must  be  dried  quickly  and  at  a  comparatively 
low  temperature  in  order  to  obtain  a  successful  product.  It  must  be 
dried  quickly  in  order  that  it  will  not  spoil  during  the  process,  and 
the  temperature  must_not  be  high  enough  to  coagulate  the  lactalbumin, 
otherwise  the  addition  of  water  would  not  restore  the  milk  to  its  former 
homogeneous  state.  Milk  is  sometimes  dried  in  a  very  thin  film  on 
metal  plates;  sometimes  in  vacuo.  In  this  way  the  milk  can  be  re- 
duced to  a  dry  state  in  a  very  short  time  and  without  reaching  a  tem- 
perature sufficiently  high  to  produce  physical  changes.  Another  method 
of  drying  milk  consists  in  atomizing  it  under  pressure  and  projecting 
it  into  a  warm  chamber,  the  temperature  of  which  is  so  regulated  that 


538  GENERAL    CONSIDERATIONS 

the  fine  particles  are  completely  deprived  of  their  water  before  they 
reach  the  bottom  of  the  vessel.  The  milk  is  thus  reduced  almost  at 
once  to  a  fine  powder.  Dried  milk  when  mixed  with  water  is  practically 
restored  to  its  original  condition.  Milk  powder  should  be  either  kept 
in  a  cool  place  or  sealed  in  air-tight  packages  in  order  to  prevent  the 
fat  becoming  rancid.  Dry  powdered  milk  properly  cared  for  will  keep 
almost  indefinitely.  Since  practically  88  per  cent,  of  milk  is  water, 
there  is  a  decided  economic  gain,  so  far  as  the  handling  and  transporta- 
tion are  concerned.  Powdered  milk  should,  of  course,  be  made  from 
milk  derived  from  healthy  cows  handled  under  sanitary  conditions  and 
free  from  infection.  The  milk  may  be  pasteurized  before  it  is  reduced 
to  a  powder.  Powdered  milk  is  finding  an  increasing  and  legitimate 
field  of  usefulness  for  cooking,  household  purposes,  and  even  as  a 
beverage  for  adults.  It  should,  however,  not  be  depended  upon  for 
infant  feeding. 

Salting  and  Pickling. — The  preservation  of  meat  with  brine  or  com- 
mon salt  is  one  of  the  oldest  processes  known.  The  brine  should  con- 
tain from  18  to  25  per  cent,  of  salt.  For  red  meats  a  little  potassium 
nitrate  is  often  added;  this  salt  has  slight  antiseptic  properties,  but 
brings  out  the  red  color.  In  the  processes  of  salting  some  of  the  meat 
protein,  bases,  and  extractives  are  dissolved  out  and  the  fibers  become 
hardened;  the  nutritive  value  and  digestibility,  therefore,  is  somewhat 
diminished. 

Pickling  includes  preservation  of  food  in  brine,  vinegar,  weak  acids, 
and  the  like.  These  substances  have  antiseptic  and  also  feeble  germi- 
cidal properties,  depending  upon  their  concentration. 

Pickled  meats  are  prepared  by  soaking  meat,  especially  pork,  in  a 
brine  made  of  common  salt,  though  other  substances,  such  as  sugar, 
vinegar,  and  spices,  are  often  added.  Chemical  preservatives  are  some- 
times added  to  the  brine.  Those  most  frequently  used  are  sulphite  of 
soda  or  boric  acid.  With  proper  methods  these  added  chemical  anti- 
septics are  not  necessary.  The  vinegar  which  is  employed,  or  acetic 
acid,  may  be  injected  into  the  carcass  before  it  is  cut  up.  When  the 
arteries  are  filled  with  vinegar  in  this  way  it  rapidly  permeates  to  all 
parts  of  the  meat  and  acts  as  an  excellent  and  unobjectionable  preserva- 
tive in  cases  where  an  acid  taste  is  desired.  It  is  stated  that  carcasses 
which  have  been  injected  with  vinegar  are  easily  preserved  and  require 
far  less  salt  and  other  condimental  substances  than  when  not  so  treated. 
The  process  has  no  sanitary  objections. 

Trichina  die  after  a  prolonged  period  of  pickling.  Cysticerci  are 
killed  in  21  days'  exposure  to  25  per  cent,  brine.  Many  pathogenic 
bacteria  die  in  brine  of  this  concentration,  but  the  salt  must  be  looked 
upon  as  an  antiseptic  rather  than  a  germicide;  that  is,  it  prevents 
growth  rather  than  kills  the  bacteria  that  are  present.    From  a  sanitary 


PEESERVATIOI^   OF  FOODS  539 

standpoint  there  is  some,  though  slight,  danger  of  conveying  infection 
in  foods  that  have  been  improperly  salted  or  pickled.  Attention  is 
called  to  the  fact  that  the  cases  of  botulism  studied  by  von  Ermengen 
were  caused  by  ham  kept  in  brine  under  conditions  favoring  anaerobic 
growth. 

Decomposition  may  also  be  arrested  by  the  use  of  syrups,  which  hiave 
an  entirely  similar  action  to  that  of  salt,  vinegar,  or  weak  acids;  that 
is,  a  strong  solution  of  sugar  will  prevent  growth,  but  cannot  be  de- 
pended upon  to  kill  parasites.  However,  most  of  them  die  under  such 
conditions  in  the  course  of  time.  As  most  preserved  foodstuffs  are 
cooked  before  eaten,  there  is  small  danger  in  articles  prepared  by  these 
processes. 

Jellies  and  Preserves. — By  preserving  is  commonly  understood  the 
addition  of  a  large  amount  of  sugar. '  The  principal  preserves  are  jel- 
lies, marmalades.  Jams,  and  fruit  butters.  These  substances  are  en- 
tirely free  from  the  danger  of  conveying  infection,  not  only  on  account 
of  the  antiseptic  action  of  the  sugar,  but  for  the  further  reason  that 
they  are  always  cooked  in  preparation.  Jellies  are  frequently  adulter- 
ated by  the  substitution  of  apple  stock.  Apples  contain  a  large  num- 
ber of  pentose  bodies  which  favor  jellification.  A  common  method  of 
manufacturing  jelly  for  the  trade  has  been  to  use  a  stock  of  apple 
juice  or  cider,  or  a  preparation  made  from  the  cores,  skins,  and  re- 
jected portions  of  the  apple  at  evaporating  factories,  or  from  whole 
rejected  apples.  This  stock  is  used  as  a  common  base  for  the  manu- 
facture of  jellies  of  different  kinds.  Apple  juice  used  as  a  substitute 
for  other  fruit  juices  in  the  making  of  preserves  is  a  common  fraud 
and  an  adulteration,  according  to  the  Food  and  Drugs  Act,  unless 
plainly  stated  upon  the  label.  Phosphoric  acids  and  other  acids  are 
added  to  jellies  to  enable  jellification  to  take  place  with  the  use  of  less 
fruit  and  more  water.  Jellies  are  also  adulterated  with  artificial  color- 
ing matter,  particularly  the  coal-tar  dyes.  Artificial  flavors  which  closely 
resemble  the  particular  flavor  desired  are  sometimes  employed.  The 
chemical  preservatives  most  frequently  added  to  jellies  and  preserved 
fruits  are  salicylic  acid,  benzoic  acid,  or  benzoate  of  soda. 

Smoking. — The  smoking  fish,  beef,  hams,  and  other  food  products 
consists  mainly  in  rapid  drying  plus  the  germicidal  action  of  certain 
substances  in  the  smoke.^  The  meat  or  fish  is  exposed  to  the  smoke 
of  a  smoldering  wood  fire  of  oak,  maple,  or  hickory,  usually  after  a 
preliminary  salting.  The  articles  so  exposed  become  dry  and  impreg- 
nated with  pyroligneous  products — acetic  acid  and  creasote,  formalde- 
hyd,  and  other  germicidal  substances.     The  penetration  is  only  partial. 

An  artificial  or  quick  method  of  smoking  meat  is  to  brush  the  pieces 

*The  process  was  probably  accidentally  discovered  in  connection  with  crude 
attempts  to  use  artificial  heat  for  drying  purposes. 


640  GENERAL    CONSIDRRATIOXS 

or  dip  them  in  pyrolignic  acid  at  definite  intervals,  and  finally  dry  in 
the  air.  The  effects  of  the  smoking  do  not  penetrate  very  far;  therefore, 
in  sausages  of  generous  diameter  putrefaction  often  occurs  in  the  interior. 
Smoked  sausage  may,  therefore,  be  dangerous,  as  far  as  various  parasites 
and  the  products  of  decomposition  are  concerned,  and  the  same  is  true 
of  smoked  ham  and  other  meats  exposed  in  large  pieces.  As  smoked 
meats  are  often  eaten  raw,  the  occasional  survival  of  parasites  in  such 
products  has  some  sanitary  significance. 

Canning.^ — The  process  of  canning  is  practically  synonymous  with 
sterilization  and  is,  therefore,  one  of  the  best  sanitary  safeguards  we 
have  against  parasites  and  the  injurious  products  of  putrefaction  in 
foodstuffs.  The  process  of  canning  was  discovered  by  M.  Appert  of  Paris 
in  1804,  long  before  the  days  of  bacteriology.  Appert  found  that  meats 
and  other  foods  in  sealed  vessels  would  usually  keep  indefinitely  if,  after 
being  sealed,  they  were  kept  for  an  hour  in  boiling  water.  He  improved 
the  process  in  1810  by  introducing  a  method  of  sealing  the  cans  after 
the  heating  process  had  driven  out  the  air  and  replaced  it  with  steam, 
so  that  when  cool  a  vacuum  is  formed.  For  all  practical  purposes  this 
is  the  universal  method  of  canning  to-day,  except  that  now  the  cans 
are  given  a  second  heating,  after  an  interval  of  a  day,  in  order  to  permit 
the  germination  of  spores  and  the  destruction  of  all  spore-bearing  bac- 
teria. In  other  words,  canning  is  a  practical  application  of  the  well- 
known  laboratory  method  of  fractional  sterilization. 

The  objection  is  sometimes  raised  that  the  contents  of  the  can  are 
improperly  sterilized  and  that  the  surviving  spores  germinate  at  the  first 
opportunity  and  cause  decomposition.  Fortunately,  an  improperly  steril- 
ized can  of  food  tells  its  own  story,  and  the  gaseous  products  of  putre- 
faction may  even  burst  the  tin  or  leave  the  food  in  such  condition  that 
when  the  can  is  opened  it  would  be  so  offensive  to  the  sense  of  smell  that 
no  one  would  use  it.  The  process  of  canning  fortunately  does  away  with 
the  necessity  of  using  chemical  preservatives  of  any  kind.  The  proper 
authorities  should  be  authorized  to  prohibit  the  canning  of  foodstuffs 
that  have  already  imdergone  perceptible  decomposition,  or,  if  not  in- 
jurious to  health,  they  should-  be  labeled  "second  quality."  The  law 
should  require  that  the  quantity  contained  within  the  can  and  the  date 
on  which  it  was  put  up  as  well  as  the  amount  should  be  stamped  in 
the  tin.  This  phase  of  the  question  is  perhaps  more  of  economic  than 
of  hygienic  importance,  but  will  be  required  in  time  as  surely  as  the 
present  law  now  requires  honest  labeling  in  other  particulars. 

Sometimes  scraps  or  inedible  portions  of  diseased  or  decayed  meats 
are  canned  and  the  flavor  disguised.  This  cannot  be  too  severely  con- 
demned if  sold  as  first  quality. 

Before  meats  are  canned  they  are  first  parboiled  for  eight  co  twenty 
minutes,  in  order  to  secure  the  shrinkage  before  the  meat  is  placed  in 


PRESERVATION   OF  FOODS  5il 

the  can.  In  the  parboiling  there  is  a  certain  loss  of  fat,  soluble  mineral 
matter,  meat  bases,  and  water.  However,  the  shrinking  of  the  meat  con- 
centrates it,  as  far  as  nutritive  value  is  concerned,  and,  therefore,  com- 
pensates for  the  loss.  The  parboiled  meat  is  then  placed  in  the  tin  and 
a  small  quantity  of  the  soup  liquor  added.  The  cans  are  closed  and  sol- 
dered and  then  placed  in  autoclaves  and  subjected  to  steam  under  pres- 
sure. Usually  a  small  hole  is  left  in  the  can  in  order  to  permit  the  exit 
of  air  and  gases.  This  is  sealed  ofE  at  once  after  heating.  The  cans  are 
then  subjected  to  a  second  heating  at  225°  to  250°  F.  for  one  to  two 
hours.  A  modified  process  consists  in  placing  the  cans  upon  an  endless 
conveyor  which  exposes  the  can  to  a  high  temperature  in  an  oil  bath  a 
sufficient  length  of  time  to  sterilize  the  contents  at  one  exposure. 

In  Germany  tuberculous  and  trichinous  meat  is  sterilized  and  sold  as 
second  quality  meat  in  accordance  with  the  third  class  or  "freihanh" 
meat  system.  There  is  no  known  sanitary  objection  to  this  practice, 
provided  the  sterilization  is  complete  and  the  label  represents  the  true 
nature  of  the  product. 

Canned  foods  are  sterile  foods  and,  therefore,  generally  safer  than 
fresh  foods.  Fresh  foods,  of  course,  are  to  be  preferred  to  those  that 
have  been  sterilized,  although  many  unsterilized  foods  are  more  danger- 
ous in  the  fresh  state  than  after  they  have  been  exposed  to  a  high  tem- 
perature. The  process  of  canning,  discovered  by  Appert  and  afterward 
perfected  through  the  work  of  Pasteur,  has  proven  of  inestimable  benefit 
to  mankind.  It  enables  nourishing  food  of  a  perishable  character  to  be 
kept  and  transported  to  great  distances  and  to  be  used  in  localities  where 
fresh  foods  are  unobtainable.  Without  this  method  of  preserving  foods 
the  pioneer  and  the  explorer  would  be  seriously  handicapped.  Large 
army  and  navy  maneuvers  would  be  materially  impeded,  and  great  metro- 
politan cities  would  be  impossible.  Wiley  states  that  "the  winning  of  the 
West  has  been  marked  by  the  debris  of  the  rusty  can." 

Canned  foods  are  not  only  safe,  but  are  quite  as  nutritious  as  the 
original  articles.  The  process  permits  us  to  have  a  well-balanced  ration 
throughout  the  year — irrespective  of  season.  The  canning  industry  is 
growing  to  enormous  proportions,  and,  on  account  of  the  great  impor- 
tance of  the  process,  the  character  and  quality  of  foods  thus  preserved 
should  be  wholly  above  suspicion,  and  no  adulteration  or  sophistication 
of  any  kind  permitted-.  Every  can  should  be  plainly  stamped  with  the 
quantity  and  true  nature  of  its  contents  and  also  the  date  when  it  was  first 
sterilized. 

Concerning  the  character  of  the  container  Wiley  states:  "Much  in 
the  direction  of  securing  a  better  product  may  be  accomplished  by  a  more 
careful  selection  of  the  container.  The  common  method  of  preserving 
canned'  goods  is  in  tin.  This  material,  as  well  known,  is  placed  on  the 
surface  of  sheet  iron  and  should  be  free  of  other  metals.    Lead  especially 


543  GENEEAL    CONSIDERATIONS 

should  be  excluded  from  the  composition  of  the  tin  as  far  as  possible. 
In  spite  of  all  these  precautions,  however,  the  coating  of  the  tin  is  some- 
times broken,  so  that  the  iron  itself  may  be  attacked,  perforations  result, 
and  the  package  of  goods  be  spoiled.  More  frequently,  however,  the  ero- 
sion of  the  tin  plate  occurs  over  widely  extended  areas,  introducing  into 
the  contents  of  the  package  a  considerable  quantity  of  tin  salts.  This 
may  be  prevented  to  a  certain  degree  by  coating  the  surface  of  the  tin 
with  a  gum  or  varnish  which  is  not  acted  upon  by  the  contents  of  the 
package.  G-lass  is  also  coming  into  more  general  use,  and  if  it  could  be 
secured  of  a  character  to  avoid  breakage  it  would  be  possible  to  replace  to 
a  considerable  extent  the  tin  packages  now  in  such  common  use,  and  thus 
prevent  the  introduction  of  soluble  tin  salts  into  food.  In  this  case  the 
glass  itself  should  be  free  of  lead,  borax,  and  fluorids.  A  glass  package 
is  now  coming  into  use  which  is  tough  and  resistant  to  ordinary  causes 
of  fracture.     Much  may  be  expected  from  progress  in  this  direction.'^ 

Chemical  Preservatives. — Chemical  preservatives  are  nothing  more 
nor  less  than  antiseptic  substances;  that  is,  substances  which  restrain 
the  growth  and  development  of  bacteria  and  molds.  Chemical  preserva- 
tives in  the  proportions  commonly  used  may  have  little  or  no  germicidal 
action.  Such  substances  as  sugar,  salt,  vinegar,  vinegar  extract  of  spices, 
and  the  pyroligneous  products  in  wood-smoke  are  not  regarded  as  "chem- 
ical" preservatives,  but  as  "natural"  preservatives  or  condimental  sub- 
stances, although  their  mode  of  action  is  precisely  the  same  as  the  chem- 
ical preservatives.  There  is  a  great  prejudice  against  the  use  of  any 
preservative  for  our  foods  if  this  preservative  is  a  "chemical"  or  "drug,'^ 
whereas  no  objection  is  raised  to  the  same  substance  if  derived  from 
"natural"  sources.  Thus,  foods  exposed  to  a  smoldering  wood-fire  become 
impregnated  with  pyroligneous  acid,  which  includes  creasote,  acetic  acid, 
and  probably  formaldehyd  and  other  substances  having  antiseptic  prop- 
erties. This  method  of  food  preservation  is  not  only  countenanced  by 
the  law,  but  is  favored  on  account  of  the  savory  result  and  the  antiquity 
of  the  process. 

The  great  increase  in  the  use  of  chemical  preservatives  in  foods  dur- 
ing the  last  fifty  years  is  ovtdng  to  the  fact  that  this  is  the  cheapest  and 
surest  method  of  preservation,  thus  offering  a  convenient  method  of  sup- 
plying the  needs  of  large  communities  as  well  as  remote  places.  The 
question,  therefore,  has  an  economic  side  that  cannot  be  disregarded. 
Here,  however,  we  must  confine  ourselves  to  the  health  aspect  of  the 
problem.  Fortunately  we  possess  two  efficient  and  wholly  unobjectionable 
processes  for  the  preservation  of  food,  viz.,  refrigeration  and  sterilization 
by  heat,  which  for  the  most  part  make  it  unnecessary  to  resort  to  the 
use  of  chemical  preservatives.  One  of  the  most  objectionable  uses  that  . 
can  be  made  of  chemical  preservatives  or  any  other  method  of  food 
preservation  is  to  conserve  foods  which  are  so  decayed  as  to  be  unfit 


PEESERVATION   OF  FOODS  543 

or  possibly  injurious  to  health  if  used  fresh.  The  law  cannot  be  too 
strictly  enforced  in  order  to  prohibit  the  use  of  chemical  preservatives 
and  condiments  used  to  disguise  such  foods,  which  may  then  be  sold  at 
high  prices  as  first  quality. 

Upon  general  principles  it  is  undesirable  to  add  a  chemical  sub- 
stance of  whatever  nature  to  food  for  the  purpose  of  preserving,  coloring, 
or  improving  its  appearance,  and  in  most  countries  this  practice  is  pro- 
hibited by  law.  There  are,  however,  a  few  instances  in  which  the  addition 
of  some  chemical  preservatives  in  minimal  amounts  seems  harmless, 
and  occasionally  even  desirable,  as,  for  example,  small  quantities  of 
benzoate  of  soda  in  catsup;  a  thin  film  of  gum  benzoin  as  a  protective 
coating  for  chocolate,  etc. 

Ko  sweeping  generalization  can  be  made  concerning  all  chemical  pre- 
servatives. Each  substance  must  be  considered  for  itself,  and  each  sub- 
stance must  further  be  considered  in  relation  to  the  particular  foodstuff 
for  which  it  is  proposed.  It  may,  however,  be  stated  as  a  general  rule 
that  any  chemical  which  is  poisonous  in  large  amounts  should  be  con- 
sidered as  poisonous  in  small  amounts  until  the  contrary  is  proven. 
In  other  words,  the  consumer  is  entitled  to  the  benefit  of  the  doubt. 
The  toxicology  of  various  food  preservatives  is  in  its  infancy  and  fre- 
quently presents  a  very  difficult  and  complex  problem.  Thus,  lead  in 
one  large  dose  is  not  particularly  harmful.  The  older  practitioners 
frequently  gave  twenty,  thirty,  and  more  grains  of  sugar  of  lead  (ace- 
tate of  lead)  for  diarrheal  affections.  Only  a  minute  portion  of  the 
lead  taken  in  one  large  dose  is  absorbed;  the  rest  is  quickly  eliminated. 
However,  if  the  same  amount  of  lead  should  be  taken  in  small  sub- 
divided daily  doses,  enough  would  be  absorbed  and  retained  by  the  tissues ; 
the  poisonous  action  would  be  cumulative,  so  that  serious  chronic  lead 
intoxication  would  result.  On  the  other  hand,  hydrocyanic  acid,  one 
of  the  most  poisonous  chemicals  known,  is  harmless  in  small  amounts, 
for  the  reason  that  when  introduced  into  the  body  it  meets  the  available 
sulphur  (HoS),  with  which  it  unites  to  form  a  sulphocyanid,  as  KSCN. 
The  potassium  sulphocyanid  is  not  poisonous,  and  it  has  been  shown 
experimentally  that  animals  are  able  to  withstand  larger  quantities  of 
hydrocyanic  acid  by  first  giving  them  substances  which  increase  the 
available  amount  of  sulphur  to  form  this  chemical  combination.  Ben- 
zoic acid  in  large  amounts  is  irritating  and  produces  well-defined  symp- 
toms of  poisoning;  small  amounts  of  benzoic  acid  are  paired  in  the 
liver  and  eliminated  by  the  kidneys  as  hippuric  acid,  a  normal  and  harm- 
less constituent  of  the  urine.  Hydrochloric  acid,  common  salt,  and  pos- 
sibly acetic  acid  and  alcohol  are  all  poisonous  in  large  amounts,  but 
which  may  be  regarded  as  harmless  if  the  amounts  taken  are  sufficiently 
small. 

The  point  at  issue  now  is  to  determine  which  of  the  chemical  sub- 


544  GENEEAL    CONSIDERATIONS 

stances  are  injurious  to  health.  ]n  the  present  transitional  state  of  our 
knowledge  it  is  not  possible  to  make  a  final  statement  concerning  all  or 
perhaps  any  one  of  them.  It  is  well  known  that  the  most  serious  poisons 
may  be  taken  in  minute  amounts  without  apparent  injury.  In  fact, 
many  medicinal  substances  in  the  pharmacopeia  are  very  poisonous,  but 
in  therapeutic  doses  may  be  quite  beneficial.  The  effect  of  the  con- 
tinued use  of  chemical  substances  in  small  amounts  will  require  long 
and  patient  observation  to  determine  whether  or  not  they  should  be 
permitted  as  food  preservatives.  Of  all  the  substances  so  far  brought 
forward,  the  least  harmful  is  benzoic  acid  and  benzoate  of  soda.  There 
can,  however,  be  no  defense  for  the  use  of  formaldehyd,  salicylic  acid, 
sulphites,  and  a  host  of  other  chemicals.  So  far  as  we  know  the  human 
organism  possesses  no  natural  mechanism  for  rendering  them  harmless. 

There  can  be  no  defense  for  the  use  of  chemical  preservatives  to  hide 
inferiority.  This  is  well  illustrated  in  the  case  of  bleached  flour.  The 
only  purpose  of  the  bleaching  is  to  make  the  flour  from  a  dark  wheat 
look  as  white  as  the  best  patent  flour.  It  was  recently  discovered  that 
this  "artificial  aging"  of  flour  may  be  accomplished  by  adding  nitrogen 
peroxid.  The  flour  absorbs  this  poisonous  gas  as  a  sponge  absorbs  water 
and  instantly  becomes  white.  Processes  of  this  kind  should  be  regarded 
as  a  comm'on  fraud,  for  the  flour  is  not  improved  in  any  way  except  in 
appearance,  which  is,  after  all,  a  deception.  The  silly  process  of  modi- 
fying the  natural  colors  of  food  is  illustrated  in  the  use  of  copper  sul- 
phate to  give  peas  a  bright  green  hue,  and  the  use  of  anilin  dyes  in 
glucose,  jellies,  fruit  juices,  ices,  and  other  substances  to  imitate  the 
color  of  natural  flavoring  extracts.  "Natural"  colors,  such  as  caramel 
and  vegetable  substances,  are  also  frequently  used.  The  substitution  of 
cheap  chemicals  for  high-priced  natural  flavoring  extracts,  the  substitu- 
tion of  acetic  acid  or  even  mineral  acids  for  genuine  vinegar,  the  sub- 
stitution of  saccharin  for  sugar,  the  paraffin  polishing  of  rice,  and  sim- 
ilar devices  are  nothing  but  common  frauds,  which  may  in  some  cases 
also  be  injurious  to  health. 

Benzoic  Acid  and  Benzoate  of  Soda. — Benzoic  acid  is  an  organic 
acid  contained  largely  (12  to  20  per  cent.)  in  gum  benzoin,  and  also 
in  balsam  of  Peru  and  balsam  of  Tolu.  It  is  obtained  from  gum  ben- 
zoin, from  the  urine  of  herbivorous  animals,  and  artificially  from  toluen, 
by  treating  it  with  chlorin  and  heating  with  water  to  150°  C. 

The  storm  center  of  the  question  of  chemical  preservatives  in  this 
country  has  raged  about  the  use  of  sodium  benzoate.  Wiley  conducted 
experiments  upon  a  number  of  healthy  individuals  known  as  the  "poison 
squad."  These  men  were  given  rather  large  quantities  of  sodium  ben- 
zoate with  their  meals  and  the  result  seemed  to  be  an  impairment  of 
the  appetite,  disturbance  of  digestion,  and  other  injurious  effects  in 
certain  instances.     On  the  other  hand,  the  Eeferee  Board  appointed  by 


PRESEEVATIOX   OF  FOODS  545 

President  Eoosevelt  and  consisting  of  Eemsen,  Chittenden,  Long,  Taylor, 
and  Herter  found  that  moderate  quantities  over  a  period  of  four  months 
have  no  appreciable  influence  upon  health. 

The  reason  why  benzoic  acid  in  moderate  amounts  is  believed  to  be 
harmless  is  that  the  body  possesses  a  special  mechanism  for  taking  care 
of  this  substance.  Many  of  our  ordinary  foods  contain  substances  which 
are  transformed  in  the  body  into  benzoic  acid.  Some  foods,  such  as 
cranberries,  contain  this  acid  in  notable  amounts.  Benzoic  acid  meets 
glycocoll  (one  of  the  decomposition  products  of  protein)  in  the  liver. 
Benzoic  acid  and  glycocoll  form  hippuric  acid,  a  normal  and  harmless 
constituent  of  the  urine.  We,  therefore,  know  that  the  human  organism 
is  prepared  to  take  care  of  and  render  harmless  a  certain  amount  of 
benzoic  acid;  we  know  that  this  mechanism  is  a  very  eificient  one,  and 
is  capable  of  taking  care  of  relatively  large  amounts  of  benzoic  acid. 

There  can  be  no  serious  objection  from  the  standpoint  of  health  to 
the  addition  of  0.1  per  cent,  of  sodium  benzoate  to  catsup,  on  account 
of  the  small  quantity  of  this  article  consumed  at  any  one  time,  and 
further  on  account  of  the  long  time  a  bottle  of  catsup  is  usually  kept 
after  it  is  opened  in  the  household.  There  is,  thus,  the  added  economic 
gain  of  preserving  the  catsup  until  it  is  all  consumed.  The  same  ob- 
ject may  be  obtained  by  the  use  of  a  sufficiently  strong  vinegar  extract 
of  spices,  but  the  question  may  be  asked  whether  the  aromatic  and 
preserving  substances  in  the  vinegar  extract  of  spices  may  not  be  more 
irritating  than  the  sodium  benzoate. 

Hoffman  and  Evans  ^  have  shown  that  ginger,  black  pepper,  and 
cayenne  pepper  fail  to  prevent  the  growth  of  microorganisms.  Xutmeg 
and  allspice  have  slight  antiseptic  properties,  but  only  for  a  very  few 
days.  Cinnamon,  cloves,  and  mustard,  on  the  other  hand,  have  very 
marked  antiseptic  powers  and  are  valua1)le  preservatives.  The  active 
antiseptic  constituents  of  mustard,  cinnamon,  and  cloves  are  the  aromatic 
or  essential  oils  which  they  contain. 

Wo  one  would  advocate  the  promiscuous  use  of  sodium  benzoate  in 
foodstuffs  generally.  Its  use  in  such  foods  as  cider  or  tomato  soup  may 
be  questioned  on  account  of  the  amounts  that  would  be  taken  in  such 
articles.  Further,  benzoate  of  soda  placed  in  an  acid  medium  becomes 
benzoic  acid.  It  is  difficult  to  know  where  to  draw  the  line,  and  the 
consumer  must  be  given  the  benefit  of  the  doubt,  but  the  evidence  seems 
fairly  well 'established  that  in  the  case  of  benzoate  of  soda  small  amounts 
are  harmless. 

The  question  has  a  large  economic  significance  in  addition  to  its 

sanitary  aspect,  for  it  is  claimed  that  benzoates  as  well  as  other  chemical 

preservatives  permit  the  use  of  rotten  tomatoes,  skins,  and  undesirable 

food  which  otherwise  could  not  readily  be  preserved.     Benzoate  of  soda 

^Journal  of  Industrial  and  Engineering  Chemistry,  Nov.,  1911,  p.  835. 

19 


546  GENEEAL    CONSIDEEATIONS 

is  a  rather  feeble  germicide  at  best,  and  in  such  dilute  proportions  as 
0.1  per  cent,  has  feeble  antiseptic  power. 

Borax  and  Boric  Acid. — Both  boric  acid  and  borax  are  only  mild 
antiseptics.  They  are  not  very  potent  germicides.  They  are  generally 
used  together,  for  the  reason  that  the  combination  of  the  two  is  more 
efficient  than  either  one  alone.  Locally  boric  acid  is  not  very  irritating, 
and  for  this  reason  it  has  been  extensively  used  in  surgical  practice. 
To  some  skins,  however,  it  is  very  irritating,  and  cases  are  reported  of 
its  absorption  from  wounds  and  cavities  when  used  too  freely,  causing 
depression  and  eruptions,  such  as  erythema  and  urticaria.  Fatal  results 
have  been  reported  in  a  few  cases  from  injecting  the  solution  into  abscess 
sacs,  and  from  washing  out  the  stomach  with  it. 

Boric  acid  and  borax  are  used  for  preserving  meats,  milk,  butter, 
oysters,  clams,  fish,  sausage,  and  other  foods.  For  meat  it  is  often  mixed 
with  salicylic  acid  and  applied  externally.  For  milk  it  was  a  common 
practice  to  add  to  one  quart  of  milk  10  grains  of  a  mixture  of  equal  parts 
of  borax  and  boric  acid;  for  butter  the  amount  used  is  about  one-tenth 
of  an  ounce  to  the  pound. 

The  effect  of  small  amounts  of  boric  acid  and  borax  upon  healthy 
human  beings  has  been  extensively  studied  and  has  resulted  in  conflicting 
testimony. 

On  one  hand  we  have  the  researches  of  Chittenden  ^  and  Liebreich  ^ 
with  dogs  fed  upon  articles  containing  borax  and  boric  acid.  To  say 
the  least,  in  both  series  the  digestion  of  the  food  was  not  notably  im- 
paired and  the  animals  gained  in  weight.  The  same  result  followed 
the  experiment  made  by  Liebreich  upon  rabbits  and  guinea-pigs.  ISTo 
injury  appears  to  have  followed  the  administration  of  boric  acid  to 
pigs,  calves,  and  children  by  the  British  Commission.^  Tunnicliffe  * 
made  experiments  from  which  he  inferred  that  neither  borax  nor  boric 
acid  affected  the  health  of  the  children  experimented  on.  Vaughan  and 
Veenboer  ^  conclude  that  in  the  small  amounts  required  for  preserving 
cream  and  butter,  and  that  used  as  an  external  dust  on  hams  and  bacon, 
both  boric  acid  and  borax  are  unobjectionable  from  a  sanitary  standpoint. 

On  the  other  hand,  the  experiments  made  by  H.  E.  Annette  ®  led 
him  to  an  opposite  conclusion.  He  found  boric  acid  injurious  to  kittens, 
and  naturally  assumed  that  the  use  of  milk  containing  it  might  be  hurt- 
ful to  young  infants.  Foster  and  Schlenker  '^  found  that  albumin  diges- 
tion was  impaired  by  boric  acid,  which  also  produced  increased  desquama- 

^  American  Jour,  of  Physiology,  1898. 

'^  Vierteljahresschrift  fiir  gericht.  Med.,  1909;   also  Lancet,  Jan.  6,   1900. 
^  Vierteljahresschrift  fiir  gericht.  Med.,  1901. 
*  Journal  of  Hygiene,  1901. 
^American  Medicine,  March  13,   1902. 
"Lancet,  Nov.  11,  1899. 

'  Quoted  in  report  of  Kober  on  "Milk  Preservatives,"  U.  S.  Senate  Commis- 
sion, 1902. 


PEESEEVATION  OF  FOODS  547 

tion  of  the  intestinal  epithelium.  Doane  and  Price  ^  made  experiments 
on  calves  which  indicate  that  horax  and  boric  acid  in  milk  retard  diges- 
tion to  a  slight  extent. 

As  these  substances  are  not  normal  constituents  of  the  body,  nor 
are  they  normal  constituents  of  foods,  the  conservative  course  would  be  to 
avoid  their  use  until  satisfactory  evidence  has  been  adduced  that  they 
are  free  from  harm  in  the  amounts  commonly  used  for  preserving  food. 

FoEMALDEHYD. — Fomialdehyd  has  been  and  still  is  used  extensively 
as  a  preservative  for  milk  and  other  articles  of  food.  Formaldehyd  in 
large  quantities  is  exceedingly  irritating,  and  death  in  isolated  instances 
has  been  reported  from  the  swallowing  of  amounts  from  1  to  3  ounces. 
There  has  been  much  discussion  as  to  the  effect  of  the  small  quantities 
ordinarily  used  as  a  food  preservative.  Bliss  and  Novy  ^  and  Hallibur- 
ton ^  have  shown  conclusively  that  small  quantities  of  formaldehyd 
greatly  delay  the  digestion  of  proteins  by  the  gastric  and  pancreatic 
juices,  the  digestion  of  starch  by  the  pancreatic  Juice,  and  the  curdling 
of  milk  by  rennet.  It  is  also  known  that  some  individuals  are  especially 
susceptible  to  the  effect  of  formalin,  small  quantities  in  the  food  causing 
dyspepsia  and  other  disturbances  of  digestion.  Formaldehyd  unites 
directly  with  protein  matter  to  form  new  compounds  of  an  undetermined 
nature.  Thus,  formaldehyd  added  to  egg  albumin  prevents  its  coagula- 
tion by  heat,  and  added  to  gelatin  prevents  liquefaction.  It  hardens  tis- 
sues, so  that  it  will  render  fish  and  meat  tough  and  brittle,  even  in  pro- 
portions as  dilute  as  1-5,000,  hence  it  is  not  generally  applicable  as  a 
food  preservative.  In  small  amounts  it  delays  decomposition;  in  large 
amounts  it  is  an  active  germicide.  Its  use  in  milk  was  recently  advocated 
by  no  less  an  authority  than  von  Behring,  but  this  view  met  with  almost 
unanimous  protest. 

There  can  be  only  one  opinion  concerning  the  use  of  formaldehyd 
in  foods,  and  that  is  absolute  condemnation  of  the  practice.  It  is  pro- 
hibited by  the  statutes  of  practically  all  nations  having  pure  food  laws. 

Salicylic  Acid. — Individuals  differ  greatly  in  their  susceptibility 
to  salicylic  acid.  In  mild  cases  of  poisoning  with  this  substance  there 
is  a  feeling  of  fulness  in  the  head  with  roaring  sounds  in  the  ears, 
dimness  of  vision,  profuse  perspiration,  confusion,  and  dulness.  Large 
doses  of  the  acid  cause  intense  irritation  of  the  throat  and  stomach, 
leading  to  vomiting  and  difficulty  in  swallowing.  Later  there  may  be 
diarrhea.  Eczema  and  other  skin  eruptions  may  appear,  and  dimness 
of  vision  and  deafness  may  continue  for  some  time.  The  long-continued 
use  of  salicylic  acid  and  its  salts  has  led  to  a  form  of  chronic  poisoning 
in  which  the  chief  symptoms  have  been  loss  of  appetite,  diarrhea  al- 

^  Bulletin  No.  86,  Maryland  Agricultural  Experiment  Station,  Sept.,   1902. 
"Jour,  of  Exp.  Medicine,  1899,  Vol.  IV,  p.  47. 
^British  Medical  Jour.,   1900,  Vol.  II,  p.   1.. 


548  GENERAL    CONSIDERATIONS 

ternating  with  coiisijpation,  irritation  of  the  kidneys,  skin  eruptions, 
and  mental  depression.  Such  results  are  said  to  have  followed  the  use 
of  articles  of  diet  preserved  with  salicylic  acid.  The  use  of  such  foods 
may  be  objectionable  in  the  case  of  aged,  feeble,  and  susceptible  per- 
sons. Salicylic  acid  and  the  salicylates  are  more  efficient  antiseptics 
than  boric  acid  or  borax,  but  they  are  not  used  extensively  on  account 
of  the  taste,  or  rather  the  tendency  to  cause  unpleasant  flavors.  They 
are  for  the  most  part  used  in  jams,  fruit  juices,  soda  water  syrups,  cider, 
wines,  and  other  sweet  preparations.  The  objection  to  the  use  of  salicylic 
acid  in  food  is  practically  unanimous  and  well  founded. 

Sodium  Niteate. — Sodium  nitrate  or  potassium  nitrate  (saltpeter) 
is  not  used  as  a  preservative,  but  as  an  indirect  coloring  matter.  It 
retains  and  accentuates  the  red  color  of  meat.  It  is  not  known  to  be 
harmful  in  the  small  quantities  in  which  it  is  commonly  employed,  but 
must  be  regarded  as  a  fraud  when  used  to  make  stale  meat  look  fresh. 

Potassium  Permanganate  is  also  used  on  the  surface  of  meat  to 
destroy  decomposition.  This  may  be  detected  by  heating  a  knife  in 
hot  water,  plunging  it  into  the  meat,  and  withdrawing  it  quickly.  This 
brings  out  the  hidden  odors  of  putrefactive  changes. 

Sodium  Fluoeid. — Sodium  fluorid  has  been  extensively  used  as  a 
preservatiA'C,  antiseptic,  and  insecticide.  It  has  considerable  antiseptic 
power,  putrefaction  being  delayed  by  the  addition  of  1  part  to  500;  and 
1  in  200  arrests  completely  the  growth  of  bacteria.  It  is  highly  poisonous 
to  nearly  all  the  lower  forms  of  life,  especially  to  microorganisms,  includ- 
ing algae.  It  does  not  coagulate  protoplasm- but  acts  as  a  general  proto- 
plasmic poison.  For  mammals,  sodium  fluorid  is  not  a  very  toxic  sub- 
stance, the  fatal  dose  by  the  mouth  being  0.5  gram  per  kilogram  of  body 
weight,  and  subcutaneously  0.15  gram  per  kilogram  of  body  weight.  The 
fluorids  on  administration  are  deposited  in  the  bones,  which  usually 
become  white  and  brittle,  and  contain  crystals  of  calcium  fluorid.  It  is 
well  to  call  attention  to  the  fact  that  fluorin,  in  very  small  traces,  is  a 
normal  constituent  of  bone,  teeth,  milk,  eggs,  etc.  In  large  amounts  and 
concentrated,  it  is  directly  irritating  to  the  mucous  membrane  and 
produces  vomiting,  diarrhea,  and  abdominal  pains.  Death  of  a  ten-year- 
old  girl  has  been  caused  by  the  ingestion  of  one  teaspoonful  in  a  little 
water,  given  in  mistake  for  Rochelle  salts. ^  Baldwin  ^  reports  a  number 
of  cases  of  sickness  and  death  resulting  from  the  accidental  ingestion  of 
sodium  fluorid,  usually  taken  in  mistake  for  baking  powder.  Recovery 
from  non-fatal  doses  is  usually  rapid  and  complete.  There  is  no  evidence 
that  small  quantities  ingested  daily  for  a  long  period  of  time  are  harmful. 

Sodium  fluorid  forms  the  basis  of  most  roach  powders  which  contain 

^Hickey,  C.  H.:  Mass.  St.  Board  of  Health  Bull.,  Dec,  1911,  Vol.  6,  No. 
12,  p.  341. 

=*  Baldwin,  H.:     Jour.  Am.  Chem.  Soo.,   1899,  Vol.  21,  p.  517. 


PEESERVATION   OF  FOODS  549 

from  16  to  47  per  cent,  of  the  fluorid  finely  ground  up  and  intimately 
mixed  with  the  bait.    It  is  fatal  to  roaches  when  so  ingested. 

Hydrofluoric  Acid. — Schultz  ^  exposed  cats  for  four  days  to  con- 
centrated fumes  of  hydrofluoric  acid  without  serious  effects.  The  air 
was  so  impregnated  that  glass  held  at  some  distance  from  the  source 
was  etched.  Hydrofluoric  acid  is  much  used  in  breweries  for  disinfecting 
vats  and  tanks.    It  is  a  powerful  germicide. 

Sulphites. — Sulphites  act  as  antiseptics  and  also  preserve  the  red 
color  of  meats.  Sodium  sulphite  and  bisulphite  and  sulphurous  acid 
are  used  principally  upon  fresh  meats,  where  they  act  as  a  preservative 
and  as  a  retainer  of  color.  Sulphur  dioxid  is  also  much  employed  for 
the  bleaching  of  fruits.  Sulphites,  even  in  minute  amounts,  interfere 
with  the  action  of  ferments,  and  thus  influence  digestion.  Free  sulphur- 
ous acid  is  very  irritating.  Sodium  sulphite  is  very  poisonous  when 
injected  subcutaneously  or  intravenously.  Death  occurs  by  paralysis 
of  respiration.  Much  larger  quantities  are  tolerated  by  the  mouth,  the 
sulphite  being  slowly  absorbed.  The  greater  part  is  converted  to  the 
harmless  sulphate  during  and  after  absorption.  The  quantities  ordinarily 
used  in  preserved  food  cause  no  immediate  symptoms,  even  when  con- 
tinued for  several  months.  If,  however,  the  animals  are  killed  and  exam- 
ined, extensive  hemorrhagic  and  inflammatory  lesions  are  found  in 
various  organs.^  These  lesions  are  probably  due  to  destruction  of  red 
blood  cells  or  infarction.  Harrington  in  1904  also  described  nephritic 
changes.  In  1898  the  Imperial  Board  of  Health  in  Germany  forbade 
the  use  of  sodium  sulphite  in  food  on  account  of  its  dangerous  properties, 
and  it  is  also  forbidden  by  our  Federal  Pure  Food  ilct  of  1906. 

Sodium  Bicarbonate. — Sodium  bicarbonate  is  too  ineffective  as  a 
germicide  for  general  use  as  a  food  preservative.  It  is  sometimes  added 
to  milk  in  order  to  neutralize  the  excess  of  acid. 

Hydrogen  Peroxid. — Hydrogen  peroxid  is  perhaps  one  of  the  less 
dangerous  of  the  chemical  preservatives,  and  is  considered  by  some  to 
exert  no  deleterious  effect  whatever  in  the  quantities  commonly  used. 
It  is  used  for  the  preservation  of  wine,  beer,  and  fruit  juices,  and  also  in 
milk. 

Arsenic. — Arsenic  in  food  comes  from  a  variety  of  sources.  Glu- 
cose is  apt  to  contain  it,  especially  if  impure  acid  is  used  to  hydrolize 
starch  in  the  production  of  glucose.  This  was  the  source  of  the  arsenic 
in  the  beer  which  caused  the  epidemic  of  peripheral  neuritis  several 
years  ago  in  England.  Arsenic  may  also  contaminate  certain  anilin  dyes 
as  well  as  shellac,^  which  is  now  so  much  used  as  a  coating  for  some 

^Schultz,  K.:     Arch.  f.  Exp.  Path.,   1889. 

"Kionka  and  Ebstein,   1902. 

^  Smith,  B.  H. :  "The  Arsenic  Content  of  Shellac  and  the  Contamination  of 
Foods  from  This  Source,"  Cir.  91,  U.  S.  Dept.  Agr.,  Bureau  of  Chemistry, 
Washington,   1912. 


550  GENEEAL    CONSIDERATIONS 

kinds  of  cheap  confectionery  and  bakers'  goods,  and  also  as  a  varnish  on 
receptacles  and  containers  of  various  kinds. 

The  use  of  preservatives  containing  lead,  arsenic,  or  other  substances 
known  to  be  poisonous  finds  no  advocates. 


THE    PREPARATION    OF    FOOD 

Cooking. — Cooking  may  be  regarded  as  the  greatest  sanitary  inno- 
vation ever  introduced  by  man  to  protect  himself  against  infection. 
The  heat  required  for  thorough  cooking  kills  all  forms  of  infection  and, 
therefore,  renders  food  safe,  so  far  as  these  dangers  are  concerned.  The 
heat  also  destroys  most  of  the  toxic  products  of  decay;  thus,  the  true 
bacterial  toxines  are  destroyed  at  temperatures  of  about  60°  C.  Foods 
may  sometimes  contain  heat-resisting  poisons.  Thus,  boiling  has  no 
effect  upon  muscarin,  the  poisonous  principle  in  certain  toadstools.  Heat 
also  does  not  destroy  a  poisonous  principle  sometimes  found  in  mussels. 
The  colon  bacillus  and  other  microorganisms  produce  thermostable 
substances  that  are  poisonous  when  injected  into  the  lower  animals, 
but  the  relation  of  these  heat-resisting  toxic  substances  to  food  poisoning 
in  man  is  not  at  all  understood.  It  is  highly  improbable  that  foods 
ordinarily  contain  heat-resisting  poisons  resulting  from  bacterial  decom- 
position. 

Trichina  die  at  65°  C;  cysticerci,  or  the  larval  stage  of  tapeworms, 
at  53°  C;  the  non-sporulating  bacteria  are  for  the  most  part  destroyed 
at  60°  C.  Food  thoroughly  cooked  throughout  will  always  reach  these 
temperatures,  but  much  meat  and  many  vegetable  food  substances  are 
preferred  rare  or  underdone,  and,  while  the  outside  of  a  large  piece  of 
meat  may  be  thoroughly  cooked  or  even  charred,  the  interior  may  be 
practically  raw  or  at  least  not  have  reached  the  temperature  necessary 
to  destroy  parasites.  A  dish  of  spaghetti,  charred  on  the  outside,  may 
not  kill  typhoid  bacilli  in  the  centre  of  the  mass.     (Page  92.) 

Meat  that  is  well  cooked  throughout  always  reaches  from  60°-70°  C. 
on  the  inside.  It  should  be  remembered  that  heat  penetrates  a  large 
piece  of  meat  slowly.  For  example,  it  requires  li/^  hours  in  boiling 
water  for  the  temperature  to  reach  62°  C.  in  the  interior  of  a  piece 
of  meat  weighing  3%  pounds.  Meat  placed  in  a  quick  oven  or  broiled 
soon  forms  a  hard,  coagulated  and  insulated  coating  that  retains  the 
juices,  but  retards  the  penetration  of  the  heat. 

Cooking  softens  the  connective  tissue  and  renders  meat  more  ten- 
der. The  bundles  of  fibrillae  are  loosened  from  each  other,  the  albumin 
is  coagulated,  the  flavors  are  improved,  and  new  flavors  are  developed, 
all  of  which  enhances  its  digestibility. 

Metchnikoff  in  his  "new"  hygiene  dwells  upon  the  great  sanitary 


THE   PREPARATION  OF  FOOD  551 

value  of  cooking.  Perhaps  no  other  single  factor  in  preventive  medi- 
cine protects  us  to  an  equal  degree  against  infection.  Metchnikoff  be- 
lieves that  we  should  eat  nothing  in  its  raw  state.  This  seems  almost  as 
extreme  as  the  cult  which  proclaims  the  contrary.  If  for  any  reason 
cooking  were  to  ceasC;,  there  would  be  such  a  great  increase  of  infections 
and  food  poisoning  as  to  amount  to  a  calamity. 

One  of  the  important  functions  in  the  preparation  of  food  is  to 
render  it  savory,  tender,  and  appetizing.  Foods  that  appear  inviting 
aid  digestion  by  stimulating  the  secretion  and  flow  of  the  digestive 
juices.  Foods  that  are  rendered  soft  and  tender  are  more  readily  di- 
gested, but  it  should  not  be  forgotten  that  the  teeth  need  exercise  to 
keep  them  in  good  condition.  Tough  meats  may  be  pounded  to  separate 
the  connective  tissue  bundles,  or  may  be  chopped  or  minced  as  an  arti- 
ficial aid  to  mastication,  or  may  be  steeped  for  several  hours  in  fresh 
milk  or  sour  milk,  in  which  case  the  fibers  are  softened  through  the 
action  of  the  bacteria  and  their  enzymes.  In  the  case  of  vegetables, 
cooking  breaks  open  and  softens  the  cellulose  envelopes  and  fibers;  the 
starch  grains  swell  and  burst,  and  the  insoluble  starch  is  converted  into 
soluble  starch  or  dextrine. 

Fermentation  is  of  great  use  in  the  preparation  of  foods.  The  best 
example  is  the  leavening  of  bread.  The  yeast  ferments  the  carbohydrates 
in  the  flour  with  the  production  of  carbon  dioxid  and  alcohol.  The 
carbon  dioxid  renders  the  bread  porous;  the  gas  is  held  within  the  loaf 
on  account  of  the  glutenous  property  of  the  protein  (gluten)  in  the 
flour.  Fermentation  is  an  adjunct  in  the  preparation  of  many  other 
foods  and  beverages,  such  as  cheese,  sauerkraut,  vinegar,  beer,  wine, 
cider,  etc. 

The  observations  of  Becker,  Grove,  and  others  concerning  the  heat 
of  cooking  are  practical  and  important  in  the  preparation  of  food.  Ex- 
posure to  steam  at  60°  to  70°  C.  for  a  long  time  has  the  advantage  of 
cooking  foods  thoroughly  throughout.  This  treatment  prevents  burning 
or  the  results  of  overheating;  the  juices  are  retained.  The  process 
requires  little  or  no  attention.  Meat  is  thereby  rendered  tender  and 
juicy,  vegetables  thoroughly  soft,  and  the  starch  grains  are  all  opened. 
A  modification  of  this  method  is  found  in  the  fireless  cookers  now  offered 
for  sale  in  various  forms.  These  devices  consist  simply  of  a  well- 
insulated  box.  The  food  is  first  heated,  then  placed  in  suitable  compart- 
ments, and  a  temperature  above  70°  C.  maintained  for  many  hours. 

Certain  precautions  are  advisable  in  the  choice  of  pots  and  pans 
used  in  cooking.  Brass  and  copper  are  not  advisable,  and  if  used  must 
be  kept  scrupulously  clean.  Acid  foods  should  not  be  cooked  in  copper 
vessels,  and  milk  and  saccharin  substances  should  not  be  kept  in  copper 
containers  on  account  of  the  possibility  of  the  organic  acids  dissolving 
the  copper.     Tin,  nickel,  and  aluminium  ware  are  least  objectionable. 


552  GENEiiAL    (J0N>S1DEKATI0NS 

Enameled  ware  is  entirely  satisfactory,  provided  jt  d(jes  not  contain 
lead. 

Methods  of  Cooking. — Much  depends  upon  the  method  of  cooking. 
The  principal  methods  in  ordinary  use  are :  roasting,  broiling,  boiling, 
frying,  and  stewing. 

EoASTiNG  OR  BROILING  causes  Considerable  shrinking,  due  mainly  to 
loss  of  water.  The  heat  coagulates  the  exterior  of  the  meat  and  thus 
prevents  the  further  loss  of  juices  and  drying  up.  In  order  to  obtain 
adequate  heating  of  the  meat  throughout  a  large  joint  without  burning 
and  drying  the  exterior,  it  is  necessary  to  baste  it  from  time  to  time 
with  hot  melted  fat.     This  also  helps  to  form  a  protective  coating. 

In  BOILING  the  meat  is  placed  either  in  hot  or  cold  water,  depending 
upon  the  object  desired.  If  it  is  desired  to  maintain  the  flavors  within 
the  mass,  the  meat  should  be  plunged  into  boiling  water.  This  quickly 
coagulates  the  albumins  at  the  surface.  If  a  rich  broth  is  desired  the 
meat  should  be  placed  in  cold  water  and  gradually  heated.  In  this 
way  the  soluble  albumins  and  extractives  pass  out  into  the  surrounding 
water.  The  albumin  of  meat  begins  to  coagulate  at  134°  F.  (56°  C.) ; 
the  connective  tissue  is  changed  to  gelatin  and  dissolved  above  160°  F. 
(72°  C). 

Frying  consists  in  placing  meat  or  other  substances  into  very  hot 
fat,  lard,  or  vegetable  oil.  This  causes  a  speedy  coagulation  of  the 
surface  similar  in  all  respects  to  that  brought  about  in  the  first  mentioned 
process  of  boiling.  The  flavors  and  juices  are  thereby  retained.  If  the 
fat  is  not  very  hot  it  will  penetrate  the  tissues  and  cause  the  meat  or 
other  substance  to  become  greasy  and  unpalatable.  Fried  substances  are 
apt  to  be  indigestible  on  account  of  the  large  amount  of  grease  that 
adheres  to  and  penetrates  into  them. 

In  STEWING  the  meat  is  cut  into  small  pieces  and  placed  in  cold 
water,  which  then  is  heated  slowly  to  about  180°  F.  (84°  C),  at  which 
the  whole  is  kept  for  several  hours.  If  heated  above  180°  F.  the  meat 
becomes  tough,  stringy,  unpalatable,  and  of  diminished  digestibility. 


CHAPTEE  II 
ANIMAL  FOODS :    MILK 

The  animal  foods  used  by  man  are  not  of  great  variety  and  source. 
They  include  the  flesh  and  various  organs  of  the  herbivorous  animals, 
SMane,  domestic  and  wild  fowl,  eggs,  fish,  shellfish,  insects  and  their 
products  (honey),  milk,  and  milk  products.  The  flesh  of  carnivorous 
animals,  except  that  of  fish,  is  unpalatable  and,  therefore,  undesirable 
as  a  food. 

The  most  important  animal  foods  from  the  standpoint  of  the  sani- 
tarian are  milk  and  meat. 

MILK 

Milk  is  responsible  for  more  sickness  and  deaths  than  perhaps  all 
other  foods  combined.  There  are  several  reasons  for  this:  (1)  bacteria 
grow  well  in  milk;  therefore,  a  very  slight  infection  may  produce  wide- 
spread and  serious  results;  (2)  of  all  foodstuffs  milk  is  the  most  diffi- 
cult to  obtain,  handle,  transport,  and  deliver  in  a  clean,  fresh,  and 
satisfactory  condition;  (3)  it  is  the  most  readily  decomposable  of  all 
our  foods;  (4)  finally,  milk  is  the  only  standard  article  of  diet  obtained 
from  animal  sources  consumed  in  its  raw  state. 

The  total  milk  production  in  the  United  States  in  1911  was  ten 
billion  gallons.  One-quarter  of  this  is  consumed  as  milk  and  the  re- 
maining three-quarters  is  used  for  butter  and  cheese.  The  average  per 
capita  consumption  of  milk  in  the  United  States  is  0.6  of  a  pint  daily. 
More  milk  is  used  in  the  North  than  in  the  South;  very  little  in  the 
tropics,  and  practically  none  at  all  in  China,  Japan,  and  some  other 
countries.  About  16  per  cent,  of  the  average  dietary  in  the  United 
States  consists  of  milk  and  milk  products. 

Fresh  milk  products  may  be  quite  as  dangerous  as  the  milk  from 
which  they  are  made.  Milk  laws  which  ignore  milk  products  are  in- 
complete from  the  sanitary  side,  and  will  fail  to  accomplish  their  pur- 
pose from  the  economic  side. 

Milk  is  a  perfect  food  for  the  suckling.  It  contains  all  the  essen- 
tial elements  of  a  well-balanced  diet  for  the  adult,  and  at  prevailing 
prices  it  is  one  of  the  cheapest  of  the  standard  articles  of  diet.  Fur- 
thermore, it  is  readily  digestible  and  is  capable  of  a  great  variety  of 
modifications.     The  sanitarian,  therefore,  has  every  reason  to  encour- 

563 


554  ANIMAL  FOODS:  MILK 

age  the  use  of  pure  milk  as  well  as  to  discourage  the  use  of  impure 
milk. 

Composition. — Milk  is  the  secretion  of  the  mammary  gland.  In 
composition  it  is  exceedingly  complex,  consisting  chiefly  of  water;  several 
proteins  in  colloidal  suspension;  fats  in  emulsion;  sugar,  and  a  number 
of  inorganic  salts  in  solution;  also  enzymes,  as  well  as  antibodies,  cells, 
gases,  and  other  substances.  Milk  from  all  animals  shows  a  general 
agreement  in  physical  properties  and  composition,  containing  essentially 
the  same  ingredients,  but  exhibiting  differences  in  the  amounts  of  the 
several  constituents. 

In  the  fresh  state  milk  is  a  yellowish  white,  opaque  fluid.  Cow's 
milk  has  a  specific  gravity  of  1.027  to  1.035;  it  freezes  at  a  temperature 
somewhat  lower  than  the  freezing  point  of  water  ( — 0.554°  C.) ;  the 
electrical  conductivity  is  43.8X10 — *  for  cow's  milk,  and  22.6X10 — * 
for  human  milk.  In  other  words,  58  per  cent,  of  the  molecules  in  cow's 
milk  and  26  per  cent,  in  human  milk  are  dissociated.  The  specific 
heat  of  milk  containing  3.17  per  cent,  of  fat  is  0.9457.  The  coefficient 
of  expansion  is  greater  than  that  of  water.  Milk  shows  no  maximum  of 
density  above  1°  C. 

Freshly  drawn  milk  of  carnivorous  animals  is,  as  a  rule,  acid  in 
reaction.  This  is  probably  due  to  COg  and  acid  phosphates.  Human 
milk  and  that  of  most  of  the  herbivora  are  slightly  alkaline;  cow's  milk 
has  been  described  as  amphoteric. 

Under  the  microscope  milk  is  found  to  contain  fat  globules  and  cells, 
as  well  as  bacteria,  debris,  and  other  objects. 

The  gases  dissolved  in  milk  ^  are  oxygen,  nitrogen,  and  carbon  dioxid 
(3  to  4  per  cent,  by  volume).  Oxygen  and  nitrogen  are  carried  into  milk 
mechanically  from  the  air  in  the  process  of  milking.  Other  substances 
found  in  milk,  but  in  small  quantities,  are  lecithin,  cholesterin,  citric  acid, 
lactosin,  orotic  acid,  and  ammonia. 

The  composition  of  cow's  milk  may  be  understood  from  the  schemes 
prepared  by  Lucius  L.  Van  Slyke  and  S.  M.  Babcock,  given  on  page  555. 

Proteins. — The  three  proteins  constantly  found  in  milk  are  casein, 
lactalbumin,  and  laetoglobulin.  A  trace  of  fibrin,  mucin,  and  other  pro- 
teins sometimes  occurs. 

The  proteins  in  milk  of  a  given  species  are  quite  constant  both  in 
composition  and  amount;  it  is,  therefore,  not  necessary,  as  a  rule,  to 
make  a  special  analysis  for  them.  They  may  be  estimated  by  subtract- 
ing the  fat,  sugar,  and  ash  from  the  total  solids. 

Casein  is  a  highly  specialized  protein  found  in  the  secretion  of  the 
milk  glands  of  all  mammals,  but  nowhere  else  in  nature ;  it  is  a  nucleo- 
albumin,  and  as  such  contains  phosphorus.  It  is  insoluble  in  water,  but 
by  virtue  of  its  property  as  an  acid  it  forms  soluble  salts  with  alkalis. 

*When  not  otherwise  specified  in  this  section  milk  refers  to  cow's  milk. 


CO 
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555 


55(5  AJSIMAL  FOODS:   MILK 

There  are  two  series  ol  casein  salts,  l)asi(;  and  ueulral;  solutions  oT  tlif 
latter  have  a  milky  appearance.  Jn  railk,  casein  is  found  dissolved  in 
the  form  of  a  neutral  calcium  salt,  which  accounts  in  part  for  the  white 
opalescent  appearance  of  milk.  Casein  exists  in  milk  in  the  form  of 
caseinogen,  that  is,  casein  in  combination  with  calcium  phosphate.  The 
caseinogen  is  held  in  solution  by  the  calcium  phosphate.  It  is  not  coagu- 
lated by  heat,  but  is  precipitated  by  acids,  for  the  reason  that  acids 
take  the  calcium  from  the  calcium  phosphate,  and  thus  throw  the  casein 
out  of  solution  as  a  curd.  This  flaky  or  lumpy  precipitate  is  again 
soluble  in  lime  water  and  dilute  alkalis.  Casein  is  also  throAvn  out  of 
solution  by  rennin. 

Lactalhumin  is  very  similar  to  the  serum  albumin  of  the  blood,  but 
it  appears  to  differ  from  this  in  some  particulars.  It  coagulates  by 
heating  to  70°  C,  but  not  with  dilute  acids,  and  is  precipitated  by  a 
saturated  solution  of  ammonium  sulphate,  but,  like  all  other  albumins, 
is  not  precipitated  in  a  neutral  solution  of  sodium  chlorid  and  mag- 
nesium sulphate.  Lactalhumin  contains  sulphur  but  no  phosphorus. 
It  is  present  in  amounts  varying  from  0.3  to  0.8  per  cent.,  but  is  much 
more  abundant  in  colostrum. 

Lacto globulin  occurs  in  milk  in  very  small  quantities,  merely  in 
traces,  while  colostrum  is  comparatively  rich,  in  this  protein.  It  coag- 
ulates at  75°  C,  it  is  precipitated  in  the  same  way  as  serum  globu- 
lin, and,  like  serum  globulin,  is  insoluble  in  water,  but  is  soluble  to 
some  extent  in  weak  salt  solution. 

Fat. — The  fat  is  suspended  in  the  milk  serum  in  the  form  of  an 
emulsion.  The  droplets  or  globules  vary  in  size.  On  the  average  they 
are  smaller  in  milk  from  Holstein  than  from  Jersey,  Guernsey,  or  short- 
horned  breeds.  Under  the  microscope  some  of  the  fat  globules  seem  to 
have  an  albuminous  membrane,  but  this  interpretation  is  now  ques- 
tioned. The  fat  droplets  are  lighter  than  the  milk  serum,  therefore 
they  rise  on  standing  (gravity  cream),  or  else  they  may  readily 
be  separated  by  centrifugal  force  (centrifugal  cream).  Cream,  or 
top  milk,  does  not  consist  of  fat  alone,  but  contains  all  the  con- 
stituents of  the  milk;  it  is  simply  milk  rich  in  fat.  Upon  shaking 
the  fat  globules  gradually  coalesce  into  larger  drops  and  lumps  to  form 
butter. 

The  first  milk  drawn  from  the  udder  is  commonly  poor  in  fat.  This 
is  known  as  "fore"  milk.  The  middle  portion  co?itains  about  the  average 
percentage  of  fat,  and  the  last,  known  as  "strippings,"  is  always  the 
richest  in  fat.  The  strippings  may  contain  as  much  as  9  or  10  per  cent, 
butter  fat. 

Heat  increases  the  viscosity  of  milk,  and  hence  hinders  the  rising 
of  the  fat  drops;  68°  C.  is  the  critical  temperature;  if  heated  above  this 
point  for  any  length  of  time  the  formation  of  the  cream  line  is  retarded 


MILK  557 

or  prevented.     For  this  and  other  reasons  the  richness  of  milk,  there- 
fore, cannot  always  be  judged  by  the  depth  of  the  cream  layer. 

Milk  fat  consists  of  a  mixture  of  different  neutral  fats,  the  principal 
of  which  are  olein,  palmitin,  and  stearin.  These  are  neutral  triglycerids 
of  the  corresponding  fatty  acids.  Besides  these  are  found  the  triglycerids 
of  myristic,  butyric,  and  caprylic  acids.  The  last  two  are  volatile  and 
give  to  butter  its  characteristic  odor  and  flavor.  The  composition  of  the 
fat  is  subject  to  variation,  depending  upon  racial  or  individual  peculiari- 
ties, also  upon  the  character  of  the  food  and  other  conditions. 

The  percentage  of  butter  fat  in  milk  has  long  been  one  of  the  stand- 
ards by  which  milk  is  tested.  The  richness  of  milk  gaged  by  the 
amount  of  fat  it  contains  is  more  of  an  economic  than  a  sanitary  ques- 
tion. Milk  with  a  low  percentage  of  fat  from  Holstein  cows  is  relatively 
just  as  nutritious  a  food  as  richer  milk  from  Jersey  and  Guernsey  cows; 
even  skimmed  milk  containing  little  or  no  fat  is  a  valuable  food.  The 
problem  is  one  of  honest  labeling  and  the  marketing  of  various  grades 
at  prices  corresponding  to  their  nutritive  contents.  When  the  standard 
for  butter  fat  in  milk  is  relatively  low,  say  3.25  per  cent.,  it  is  a  tempta- 
tion for  dairy  men  to  remove  the  excess.  This  is  a  fraudulent  practice 
which  should  not  be  countenanced.  A  high  fat  standard  encourages 
the  breeding  of  better  cows;  requires  caution  in  their  feeding  and  care, 
and  puts  a  premium  upon  good  dairy  methods. 

In  normal  milk  the  larger  proportion  of  the  fat  droplets  agglutinate 
into  tiny  clusters  or  masses.  At  a  temperature  of  65°  C.  or  above  these 
clusters  are  broken  up  and  the  globules  are  more  homogeneously  dis- 
tributed throughout  the  liquid.  When  milk  is  subjected  to  a  pressure 
of  about  3,000  pounds  at  a  temperature  of  about  75°  C.  the  individual 
fat  globules  are  broken  up  into  fine  particles,  which  remain  as  a  uni- 
form and  permanent  emulsion  known  as  "homogenized  milk."  This 
process  applied  to  cream  increases  its  viscosity,  so  that  cream  contain- 
ing 20  per  cent,  butter  fat  appears  to  have  the  body  and  richness  of 
a  30  per  cent,  cream. 

Researches  of  Heubner,  Keller,  and  Czerny  show  that  the  fats  and 
not  the  proteins  are  the  cause  of  much  of  the  digestive  disturbances  in 
infants.  When  the  fat  is  excessive  in  amount  the  infant  at  first  seems 
to  thrive,  but  sooner  or  later  loses  weight  and  appetite,  and  shows  other 
symptoms,  associated  with  stools  composed  largely  of  fat  soaps  and  of 
a  pale  gray,  hard,  and  dry  constituency.  The  alkaline  bases  are  so 
largely  drawn  upon  from  the  body  to  saponify  the  excessive  amount  of 
fat  in  the  intestines,  that  a  condition  resembling  acidosis  may  appear; 
furthermore,  fermentative  changes  take  place  in  the  intestines  and  the 
"catastrophe"  ensues. 

Fat  is  the  most  variable  constituent  in  milk.  The  amount  varies 
with  different  animals,  and  even  in  the  same  animal  from  time  to  time. 


558 


ANIMAL  FOODS:  MILK 


Milk  Sugar,  or  Lactose. — Milk  sugar,  or  lactose  (C^^^L^z^j^^),  is 
peculiar  to  milk;  it  is  found  nowhere  else  in  nature.  Its  formation 
is  not  understood.  Commercially,  milk  sugar  is  obtained  from  whey 
as  hard  rhombic  crystals,  which  have  a  slightly  sweet  taste  and  are 
soluble  in  six  parts  of  cold  water.  Lactose  is  readily  acted  upon  by 
microorganisms  and  reduced  to  glucose  and  galactose;  the  glucose  is 
further  changed  to  lactic  acid.  This  is  the  common  cause  of  sour  milk 
(see  The  Fermentation  of  Milk,  page  565). 

Lactose,  like  glucose,  reduces  Fehling's  solution  when  heated;  it  is 
dextrorotary.  When  heated  above  the  boiling  point  of  water  it  changes 
to  a  brownish  color  as  a  result  of  the  formation  of  lactocaramel. 

The  amount  of  lactose  in  milk  of  any  given  species  is  remarkably 
constant. 

Milk  Standards. — Milk  that  meets  standard  requirements  is  not 
necessarily  standard  milk.  The  legal  standards  are  minimum  require- 
ments and  express  inferiority,  if  anything.  The  standards  are  the  lowest 
grades  that  the  law  will  permit.  There  are,  in  fact,  four  standards  by 
which  milk  should  be  judged:  (1)  physical  standards;  (2)  the  chemical 
standards;  (3)  bacteriological  standards;  (4)  sanitary  standards  deter- 
mined by  inspection.  All  four  are  necessary  for  the  satisfactory  control 
of  the  milk  supply. 

The  principal  physical  standards  are  specific  gravity,  temperature, 
taste,  color,  etc. 

The  principal  chemical  standards  are  those  for  butter-fat  and  total 
solids.  The  legal  requirements  for  the  butter-fat  and  total  solids  in 
milk  vary  somewhat  in  different  states,  as  shown  by  the  following  table : 

LEGAL  REQUIREMENTS 


Fat 
per  cent. 

SoHds 
not  fat  2 
per  cent. 

Total 

solids 

per  cent. 

3.0 

Idaho 

8.0 

8.5 
9.0 
9.5 
9.0 

8.5 

8.75 

8.8 

8.0 

9.0 

9.5 

11.0 

California,  Illinois,  New  Jersey,^  New  York,i 
Wisconsin 

11.5 

Montana,  North  Dakota,  Ohio,  Porto  Rico .  .  . 
lowa,^  Michigan,^  Oklahoma^    

12.0 
12.5 

3  2 

Oregon,  Utah    .                  ...                

12.2 

3.25 

Association  of  Official  Agricultural  Chemists, 
Connecticut,    Georgia,    Indiana,    Kentucky, 
Maine,  Missouri,  North  Carolina,  South  Da- 
kota, Tennessee,  Texas,  Virginia 

Washington 

11.75 
12.00 

3.35 

Massachusetts^ 

12.15 

3  5 

Hawaii^                                           

11.5 

District  of  Columbia,  Maryland^ 

12.5 

Louisiana,  New  Hampshire 

13.0 

•  These  states  marked  do  not  directly  specify  the  solids  not  fat. 

-  The  figure  given  in  such  cases  is  the  difference  between  the  required  total  solids  and  the  re- 
quired fat. 


MILE  559 

It  has  been  found  an  advantage  to  keep  the  butter-fat  standard  rela- 
tively high  and  the  total  solids  at  a  minimum  of  12  per  cent.  This 
allows  8.5  per  cent,  for  solids  not  fat,  such  as  the  proteins,  milk  sugar, 
and  inorganic  salts.  A  3.25  per  cent,  butter-fat  and  a  12  per  cent,  total 
solids  is  the  minimum  that  should  be  allowed. 

If  the  law  recognizes  a  low  standard  for  total  solids,  it  permits 
manipulation  of  the  milk,  such,  for  example,  as  adding  water.  It  also 
encourages  the  production  of  milk  from  inferior  cows.  High  standards 
encourage  good  dairy  methods,  require  good  feed,  and  place  a  premium 
upon  the  better  breeding  of  milch  cows. 

The  determination  of  fats  and  total  solids  is  used  to  detect  skim- 
ming or  watering ;  however,  it  is  possible  to  skim  milk  or  water  it,  within 
limits,  without  the  possibility  of  detecting  it  through  the  fats  and  total 
solids. 

If  dependence  is  placed  upon  the  total  solids,  mistakes  may  also 
occur.  The  total  solids  represent  the  proteins,  fats,  sugar,  and  inorganic 
salts.  They  may  readily  be  tampered  with.  Thus  sugar  may  be  added 
to  replace  the  cream  that  is  taken  off. 

Ferments  or  "Life"  in  Milk. — Milk  contains  a  large  number  of  very 
active  ferments  or  enzymes.  These  substances  are  the  nearest  approach 
to  "life"  that  we  know  of  in  milk.  Milk  also  possesses  certain  other 
properties  common  to  blood  and  living  tissues,  but,  while  milk  may 
properly  be  regarded  as  a  vital  fluid,  it  possesses  none  of  the  funda- 
mental properties  of  life.  In  fact,  milk  begins  to  decay  the  moment 
it  is  drawn ;  ofttimes  decomposition  begins  while  the  milk  is  still  within 
the  udder.  It  would,  therefore,  be  more  proper  to  regard  milk  as  a 
dead  fluid,  in  the  same  sense  that  shed  blood  is  dead. 

The  ferments  are  believed  to  be  important  to  the  infant,  and  this 
importance  has  been  emphasized  especially  since  the  introduction  of 
pasteurization,  for  the  reason  that  a  high  degree  of  heat  destroys  them. 
Some  of  the  ferments  in  milk  are  normal  constituents  of  that  secretion, 
while  others  are  produced  by  bacteria.  Many  tests  have  been  devised 
to  determine  the  kinds  and  activity  of  the  ferments  in  milk.  The  tests 
most  frequently  and  successfully  used  are  those  for  catalases  and  re- 
ductases. The  absence  of  ferments  in  milk  indicates  that  it  has  been 
heated.  The  presence  of  certain  ferments  gives  an  indication  of  the  age 
of  the  milk,  and  the  number  of  bacteria  it  contains,  and  also  helps  to 
distinguish  between  fresh  normal  milk  and  pathologically  changed 
milk. 

The  enzymes  in  milk  are  the  following: 

Galactase. — Galactase  is  a  proteolytic  ferment,  similar  to  trypsin. 
It  was  found  by  Babcock  and  Russell  to  be  abundant  in  separator  slime. 
Ordinarily  galactase  by  itself  acts  too  slowly  to  cause  any  material 
change  in  the  proteins  in  the  short  intervals  which  elapse  between  the 


560  ANIMAL  FOODS:  MILK 

withdrawal  of  the  milk  from  the  animal  and  its  consumption  as  food. 
Snyder  claims  that  this  enzyme  probably  assists  digestion,  in  that  when 
milk  is  used  in  a  mixed  diet  the  proteins  have  been  found  to  be  from 
4  to  5  per  cent,  more  digestible  than  when  milk  is  omitted  from  the 
diet. 

Lactohinase. — Hougardy  has  recently  shown  that  milk  contains  a 
ferment  or  a  kinase  similar  to  enterokinase.  Lactokinase  has  been  found 
to  accelerate  the  digestion  of  proteins  by  pancreatic  juice.  This  property 
is  destroyed  by  heating  the  milk  at  73°  to  75°  C. 

Lipase. — This  fat-splitting  ferment  was  found  in  milk  by  Marfan 
and  Gillet.  Human  milk  exhibits  this  property  to  a  higher  degree  than 
cow's  milk.  The  former  has  a  lipolytic  activity  of  20  to  30  on  Harriot's 
scale,  while  cow's  milk  shows  an  activity  of  only  6  to  8.  Lipase  with- 
stands cold,  but  is  destroyed  by  heating  to  65°  C;  it  is  monodialyzable 
and  is  held  back  by  a  porcelain  filter.  It  probably  hydrolyzes  the  higher 
fats  of  milk,  at  least  to  some  extent,  and  may  possibly  account  for  a 
small  part  of  the  acidity  of  some  milk. 

Catalase. — Milk  contains  no  true  oxidases  or  oxidizing  ferments 
proper  (Kastle).  It  decomposes  hydrogen  peroxid  and  has  the  power 
of  effecting  the  oxidation  of  a  considerable  number  of  easily  oxidizable 
substances  in  the  presence  of  hydrogen  peroxid  or  ozonized  oil  of  tur- 
pentine. In  other  words,  milk  contains  catalase  and  peroxidase.  Cata- 
lase is  widely  distributed  among  animals  and  plants;  in  milk  it  is  prob- 
ably of  bacterial  origin.  Jolles  has  pointed  out  that  human  milk  decom- 
poses five  or  six  times  as  much  hydrogen  peroxid  as  cow's  milk.  Consid- 
erable importance  has  been  attached  to  this  difference,  which  has  also 
been  used  to  distinguish  human  milk  from  cow's  milk.  Little  is  known 
of  the  function  of  catalase.  Hydrogen  peroxid  is  probably  formed  in 
both  animal  and  vegetable  tissues  during  vital  activities.  The  catalase 
would  destroy  it  and  thus  prevent  its  accumulation  in  the  cell,  which 
otherwise  would  destroy  its  life. 

Peroxidases. — Milk  contains  substances  capable  of  inducing  the  oxida- 
tion of  guaiacum  and  other  readily  oxidizable  substances  by  means  of 
hydrogen  peroxid  or  ozonized  oil  of  turpentine.  These  substances  are 
known  as  peroxidases.  The  peroxidases  are  destroyed  when  milk  is  heated 
to  80°  C.  The  color  reactions  for  these  ferments  are  a  convenient  test 
to  determine  whether  milk  has  been  heated  beyond  a  certain  temperature 
or  not.  The  interpretation  of  this  reaction  must,  however,  be  guarded,  as 
Gillet  and  Kastle  found  that  even  normal  fresh  milks  vary  in  the  amount 
of  peroxidases  which  they  contain. 

Reductases. — Eaw  milk  possesses  reducing  properties ;  for  example,  it 
reduces  Schardinger's  reagent,  which  consists  of  a  solution  of  methylene 
blue  containing  small  amounts  of  formaldehyd.  The  reductases  in  milk 
are  probably  of  bacterial  origin.     On  account  of  the  bacterial  origin  of 


MILK 


561 


both  the  catalases  and  reductases  in  milk,  the  defection  of  these  enzymes 
has  a  sanitary  significance. 

Diastase  {Amylase). — Bechamp  in  1882  isolated  from  milk  a  fer- 
ment which  liquefies  starch  and  converts  it  into  sugar  as  readily  as 
diastaste.  These  observations  have  not  been  confirmed  by  recent  in- 
vestigation (Mora,  Van  De  Velde,  and  Landtsheer,  or  Kastle). 

Thermal  Death  Point  of  Milk  Enzymes. — The  influence  of  tem- 
perature on  the  activity  of  milk  enzymes  is  very  much  like  enzymes  from 
other  sources.  All  of  this  great  group  of  substances  stand  in  such  in- 
timate and  close  relation  to  the  vital  activities  of  the  cell  that  all  those 
conditions  and  influences  which  tend  to  destroy  the  one  tend  also  to 
destroy  the  other.  All  of  the  bacteria  in  milk  cannot  be  destroyed  with- 
out rendering  the  ferments  in  milk  inactive;  but  the  non-spore-bearing 
bacteria  can  be  killed  without  appreciable  harm  to  the  ferments,  for  in 
general  the  ferments  have  a  higher  thermal  death  point  than  such  bac- 
teria. The  activity  of  ferments  begins  to  be  influenced  at  60°  C,  and  is 
seriously  affected  at  70°  C;  at  80°  C.  they  are  destroyed.  The  non- 
spore-bearing  bacteria  are  destroyed  at  60°  C.  It  is,  therefore,  possible 
to  destroy  all  the  serious  infections  in  milk,  so  far  as  man  is  concerned, 
without  influencing  its  "life,"  so  far  as  the  ferments  are  concerned.  In 
fact,  it  has  been  shown  that  milk  heated  to  60°  C.  increases  the  activity 
of  some  of  the  ferments,  notably  the  peroxidases. 


ENZYMES  IN  MILK  AND  THEIR  THERMAL  DEATH  POINTS  i 


Galactase — Proteolytic  ferment 

70°  for  10  minutes  retards  its  action.  76°  for 
10  minutes  destroys  its  digestive  power. 
(Babcock  and  Russell.)  Not  weakened  at 
60°  for  one  hour,  (von  Freudenreich.) 
Withstands  6.5°  for  half  an  hour.  (Hippius.) 

Lactokinase— Accelerates    pancreatic 
digestion 

Destroys  at  73°  to  75°  C.  for  half  an  hour. 
Enfeebled  at  75°  for  20  minutes.  (Hon- 
gardy.) 

Lipase — Fat-splitting  ferment 

Destroys  at  70°  C.  (Harriot.)  Destroys  at 
65°  to  70°  C.  (Kastle  and  Loewenhart.) 
Withstands  60°  for  one  hour.     (Hippius.) 

Catalase — Decomposes  H2O2,  etc ...  . 

? 

Peroxidase — Oxidizes  guaiacum,  etc . . 

Destroyed  at  79°  C.  (Marfan.)  Destroys  at 
76°  C.     (Hippius.) 

Reductase — A  reducing  ferment 

Existence  is  doubtful  in  Milk. 

Diastase — Converts  starch  into  sugar . 

Probably  does  not  exist  in  Milk.  Diastasein 
saliva  destroyed  at  65°  to  70°  C. 

1  Compiled  from  Kastle. 


"Leukocytes"  in  Milk. — k  large  number  of  cells  are  normally  present 
in  milk.     These  are  not  to  be  regarded  as  the  result  of  inflammation. 


562  ANIMAL  FOODS:  MILK 

unless  they  have  the  characteristics  of  "pus"  cells..  Those  found  in 
normal  milk  are  leukocytes  and  degenerated  epithelial  cells.  The 
number  of  cells  in  milk  is  greatly  increased  in  the  presence  of  garget; 
toward  the  end  of  lactation ;  on  approaching  calving  time ;  during  periods 
of  excitement,  and  various  other  factors.  A  leukocytic  content  of  500,000 
or  over  to  the  cubic  centimeter,  especially  in  a  mixed  milk,  is  regarded 
by  the  Boston  Board  of  Health  as  suggestive  of  some  inflammatory  con- 
dition of  the  udder,  more  particularly  if  associated  with  streptococci, 
Such  milk  is  excluded  until  after  satisfactory  veterinary  inspection  of  the 
herd. 

Various  methods  have  been  proposed  to  count  the  number  of  cells 
in  milk  (see  Microscopic  Examination,  page  591). 

The  Excretion  of  Drugs  in  Milk. — The  following  drugs  taken  by  the 
mouth  have  been  found  in  the  milk  of  nursing  women :  aspirin,  iodin, 
mercury  (calomel),  arsenious  acid,  potassium  bromid,  and  probably  also 
urotropin  (hexamethylamin),  salicylic  acid,  and  salicylates,  ether,  anti- 
pyrin,  bromids,  and  many  others;  the  list  is  very  long.  It  is  probable 
that  opium,  all  volatile  oils,  purgative  salts,  and  rhubarb  are  excreted  to 
a  certain  extent  in  the  milk.  It  is  well  known  how  readily  the  flavor  of 
cow's  milk  is  afl^ected  by  turnips,  garlic,  wild  onions,  moldy  hay  and 
grain,  or  damaged  ensilage.  Fermented  distillery  waste  gives  a  bad 
flavor  and  may  also  cause  the  secretion  of  small  quantities  of  alcohol  in 
the  milk.  The  importance  of  these  facts  is  self-evident.  Cows  in  pastures 
sometimes  feed  on  poisonous  weeds,  and  these  poisons  may  pass  into  the 
milk.  In  the  production  of  certified  milk,  cows  are  never  allowed  to 
graze,  but  are  given  carefully  selected  feed.  Certain  substances,  as  en- 
silage, when  fed  to  cows,  cause  a  laxative  property  to  appear  in  the  milk, 
and  thus  it  is  possible  to  afi^ect  the  baby  through  the  feed  of  the  cow. 

The  Differences  Between  Cow's  Milk  and  Woman's  Milk. — The  table 
(page  563)  from  Eotch  summarizes  the  principal  points  of  differences 
between  cow's  milk  and  human  milk. 

The  differences  between  these  two  milks  are  greater  than  the  table 
indicates.  While  cow's  milk  may  be  modified  to  approximate  woman's 
milk  in  composition,  it  can  never  be  just  the  same  or  Just  as  good  for 
infants. 

Cow's  milk  is  more  opaque  than  woman's  milk,  although  the  latter 
may  contain  a  greater  percentage  of  fat.  This  is  due  to  the  opacity  of 
the  calcium-casein,  which  is  present  in  greater  proportion  in  cow's  milk. 
Cow's  milk  is  faintly  acid  or  amphoteric  when  freshly  drawn,  but  ordi- 
narily is  distinctly  acid  in  reaction  when  consumed.  Woman's  milk  is 
amphoteric  or  alkaline. 

There  is  three  times  as  much  protein  in  cow's  milk  as  in  woman's 
milk.  The  reason  for  this  is  obvious,  when  we  recall  that  the  ratio  of 
the  growth   of  the  calf  to  that  of  the  infant  is  about  as  two  to  one. 


MILK 


563 


Furthermore,  the  protein  in  cow's  milk  consists  chiefly  of  casein  (3.02 
per  cent.)  and  little  lactalbumin  (0.53  per  cent.),  while  woman's  milk 
contains  0.59  per  cent,  of  casein  and  1.23  per  cent,  lactalbumin.  The 
sugar  in  the  two  milks  varies  greatly  in  amount,  but  not  in  kind.  Cow's 
milk  contains  almost  four  times  the  amount  of  inorganic  salts  com- 
pared to  woman's  milk.  Of  more  importance,  the  salts  in  cow's  milk 
consist  mainly  of  the  calcium  and  magnesium,  while  those  in  woman's 
milk  consist  mainly  of  potassium  and  sodium  bases.  These  differences 
have  an  important  bearing  upon  infant  metabolism.  There  is  no  great 
difference  in  the  average  amount  of  fat  in  the  two  milks;  however,  both 
in  woman's  milk  and  in  cow's  milk  the  fat  is  the  most  variable  con- 
stituent. 

The  curd  from  cow's  milk  is  usually  tougher  and  in  larger  masses 
than  that  in  woman's  milk.  There  are  also  differences  in  the  antibodies, 
ferments,  etc. 

THE  DIFFERENCES  BETWEEN  WOMAN'S  MILK  AND   COW'S  MILK. 


Woman's  Milk  Directly  from  the  Breast 


Cow's  Milk,  Freshly  Milked 


Reaction,  amphoteric  (more  alkaline  than  acid) . . . 

Water,  87  to  88  per  cent 

Mineral  matter,  0.20  per  cent 

Total  soUds,  13  to  12  per  cent 

Fats,  4.00  per  cent,  (relatively  poor  in  volatile 
glycerids) 

Milk  sugar,  7.00  per  cent 

Proteids,  1 .50  per  cent 

Caseinogen,  3^  to  J^  of  the  total  proteids 

Whey-products,  |^  to  3^  of  the  total  proteids .  .  . 

Coagulable  proteids,  small  proportionately 

Coagulation  of  proteids  by  acids  and  salts,  with 
greater  difficulty.    Curds  small  and  flocculent . 

Coagulation  of  proteids  by  rennet,  does  not  coag- 
ulate readily 

Action  of  gastric  juice,  proteids  precipitated  but 
easily  dissolved  in  excess  of  the  gastric  juice .... 


Amphoteric  (more  acid  than  al- 
kaline). 

86  to  87  per  cent. 

0.70  per  cent. 

14  to  13  per  cent. 

4.00  per  cent,  (relatively  rich  in 
volatile  glycerids). 

4.75  per  cent. 

3.50  per  cent. 

2.66  per  cent. 

0.84  per  cent. 

Large  proportionately. 

With  less  difficulty.  Curds  large 
and  tenacious. 


Coagulates  readily. 
Proteids    precipitated 
solved  less  readily. 


but    dis- 


Classification  of  Milk. — From  a  public  health  standpoint  there  are 
only  two  kinds  of  milk — good  and  bad.  We  are,  however,  confronted 
with  a  complex  situation  which  has  resulted  in  various  schemes  for 
grading  milk  according  to  its  sanitary  quality  and  its  nutritive  value. 
Perhaps  the  most  practical  classification  has  been  advanced  by  the  govern- 
ment, viz.:  (A)  certified  milk;  (B)  inspected  milk;  (C)  market  milk. 
A  fourth  grade  known  as  "cooking  milk"  or  "milk  not  suitable  for  drink- 
ing purposes"  has  been  proposed,  but  has  not  met  with  favor  except  from 
an  economic  standpoint  in  large  cities. 

The  classification  of  the  Commission  of  Standards  of  the  New  York 
Milk  Committee  into  grades  A,  B,  and  C  will  be  found  in  the  Public 
Health  Eeports  of  Aug.  22,  1913,  p.  1743. 


564  ANIMAL  FOODS:  MTLK 

There  is  a  growing  tendency  to  classify  all  niilk  iiilo  raw  and  pas- 
teurized. This  is  the  most  satisfactory  classiiicaiioii  from  a  sanitary 
standpoint. 

The  grading  of  milk  in  accordance  with  a  simple  classification,  such 
as  recommended  by  the  Commission  of  Standards  of  the  Xew  York  Milk 
Committee  has  great  economic  and  sanitary  importance.  Such  a  system 
furnishes  the  purchaser  with  a  ready  method  of  knowing  just  what  he  is 
buying,  and  furthermore  helps  the  farmer  get  a  better  price  for  a  superior 
product. 

Certified  Milk. — The  term  "certified  milk"  was  coined  by  Dr.  Henry 
L.  Coit  of  Newark,  N.  J.,  who  in  1892,  needing  good  milk  for  his  own 
baby,  formulated  a  plan  for  the  production  of  clean,  fresh,  pure  milk 
under  the  auspices  of  a  medical  milk  commission.  The  term  "certified 
milk,"  then,  is  milk  of  the  highest  quality,  of  uniform  composition,  ob- 
tained by  cleanly  methods  from  healthy  cows  under  the  special  super- 
vision of  a  medical  milk  commission. 

The  use  of  the  term  "certified  milk"  should  be  limited  to  milk  pro- 
duced in  accordance  with  the  requirements  of  the  American  Association 
of  Medical  Milk  Commissions.'^  The  first  requisite  in  the  production  of 
certified  milk  is  to  enlist  the  cooperation  of  a  trustworthy  dairyman  who 
is  willing  to  enter  into  a  contract  with  the  medical  milk  commission. 
In  accordance  with  the  terms  of  this  contract,  the  dairyman  binds  himself 
to  comply  with  the  specifications  set  forth  and  in  return  his  milk  is 
certified. 

The  dairies  are  subjected  to  periodic  inspections,  and  the  milk  to 
frequent  analyses.  The  cows  producing  certified  milk  must  be  free  from 
tuberculosis,  as  shown  by  the  tuberculin  test  and  physical  examination 
by  a  qualified  veterinarian,  and  from  all  other  communicable  disease,  and 
from  all  diseases  and  conditions  whatsoever  likely  to  deteriorate  the  milk. 
They  must  be  housed  in  clean,  properly  ventilated  stables  of  sanitary 
construction,  and  must  be  kept  clean  and  properly  fed  and  cared  for. 
All  persons  who  come  in  contact  with  the  milk  must  exercise  scrupulous 
cleanliness,  and  must  not  harbor  the  germs  of  typhoid  fever,  tuberculosis, 
diphtheria,  or  other  infections  liable  to  be  conveyed  to  the  milk.  Milk 
must  be  drawn  under  all  precautions  necessary  to  avoid  contamination, 
and  must  be  immediately  cooled,  placed  in  sterilized  bottles,  and  kept  at 
a  temperature  not  exceeding  50°  F.  until  delivered  to  the  consumer. 
Pure  water,  as  determined  by  chemical  and  bacteriological  examination, 
is  to  be  provided  for  use  throughout  the  dairy  farm  and  dairy.  Certified 
milk  should  not  contain  more  than  10,000  bacteria  per-  cubic  centimeter, 
and  should  not  be  more  than  thirty-six  hours  old  when  delivered. 

Inspected  Milk. — This  term  should  be  limited  to  clean,  fresh  milk 

■    ^See  annual  reports  of  this  Association,  also  Public  Health  Keports,  No.  85, 
May  1,   1912. 


MILK 


)65 


from  healthy  cows,  as  determined  Ijy  the  tuberculin  test  and  physical 
examination  by  a  qualified  veterinarian.  The  cows  are  to  be  fed,  watered, 
housed,  and  milked  under  good  conditions,  but  not  necessarily  equal  to 
those  prescribed  in  the  production  of  certified  milk.  Scrupulous  cleanli- 
ness must  be  exercised  and  particular  care  be  taken  that  persons  having 
communicable  infections  do  not  come  into  contact  with  the  milk.  This 
milk  must  be  delivered  in  sterilized  containers,  and  kept  at  a  tempera- 
ture not  exceeding  50°  F.  until  it  reaches  the  consumer.  There  should 
not  be  more  than  100,000  bacteria  per  cubic  centimeter  of  inspected 
milk.    This  milk  should  be  pasteurized. 

MjlRktit  Milk. — All  milk  that  is  not  certified  or  inspected  in  ac- 


FiQ.  71. — Unsanitary  Surroundings  of  a  Cow  Barn. 

cordance  with  the  above  definitions,  and  all  milk  that  is  of  unknown 
origin,  is  classed  as  "market  milk,"  and  should  be  pasteurized. 

The  Decomposition  of  Milk. — Milk  spoils  in  various  ways  as  the 
result  of  bacterial  growth;  the  kind  of  decomposition  depending  upon 
the  kind  of  bacteria  which  predominate.  Milk,  as  a  rule,  ferments,  but 
sometimes  it  putrefies.  In  the  former  case  the  main  change  takes  place 
in  the  carbohydrates;  in  the  latter  the  proteins  are  broken  down.  The 
fermentation,  known  as  the  souring  of  milk,  is  accompanied  by  an  acid 
reaction  and  a  precipitation  of  the  casein.  Putrid  milk  turns  alkaline 
and  bitter,  owing  to  the  formation  of  peptones.  Sour  milk  is  regarded 
as  the  normal  form  of  decomposition,  because  it  is  the  usual  change 
and  is  not  harmful.  Putrid  milk  is  believed  at  times  to  contain  toxic 
substances;  it  is  at  least  suspicious. 

Sour  Milk — Lactic  Acid  Fermentation. — Milk  curdles  or  sours 
when  the  soluble  caseinogen  is  thrown  out  of  solution  and  precipitated 


566  ANIMAL  FOODS:  MILK 

as  casein.  The  caseinogen  exists  in  milk  as  a  complex  molecule  con- 
taining calcium  phosphate  loosely  bound  to  it;  it  also  contains  calcium 
as  part  of  the  molecular  complex.    The  formula  may  be  expressed  thus : 

Ca3(P04)2   (Ca.  Caseinogen) 

The  casein  is  held  in  solution  (colloidal  suspension)  by  the  calcium 
phosphate  and  other  soluble  salts  of  calcium.  Any  chemical  reaction 
that  removes  the  calcium  phosphate  from  this  combination  causes  a 
precipitation  of  the  caseinogen  as  casein.  The  casein  may  be  precipi- 
tated by  various  substances,  such  as  rennin  or  acids.  In  the  normal 
curdling  or  souring  of  milk  the  casein  is  precipitated  by  lactic  acid 
produced  through  the  action  of  bacteria  upon  lactose.  The  lactic  acid 
results  from  hydrolysis  of  the  lactose  as  follows : 

CaA,0,,+H30  =  CeH,,0e+CeH,A 

( lactose  )  =  ( galactose )  -|-  ( glucose ) 

C6Hi206=2C3H603 

,  (glucose)  =:  (lactic  acid) 

The  bacteria  usually  concernM  in  tbie  souring  of  milk  are :  B.  acidi 
lactici  of  Hueppe,  B.  lactis  acidi  of  Leichmann,  Streptococcus  lactis  of 
Kruse,  B.  hulgaricus  of  Metchnikoff,  B.  aerogenes  capsulatus  of  Welch, 
B.  coli,  and  a  great  number  of  other  microorganisms  capable  of  fer- 
menting sugar  with  the  production  of  acid. 

Sour  milk,  obtained  from  clean  milk,  is  a  beneficial  food.  It  con- 
tains myriads  of  lactic  acid  bacteria.  Metchnikoff  recently  called  at- 
tention to  the  importance  of  a  normal  lactic  acid  flora  in  the  large 
intestines,  which  inhibits  putrefactive  processes  and  thereby  stands  guard 
against  "auto-intoxication.''  He  recommended  the  use  of  certain  bacteria 
in  sour  milk,  especially  B.  hulgaricus.  It  is  a  fallacy,  however,  to  sup- 
pose that  the  flora  of  the  large  intestines  may  be  materially  influenced 
through  ingestion  of  these  bacteria  by  the  mouth,  even  when  taken  in 
enormous  numbers,  as  in  sour  milk.  A  sour  milk  diet  is  uncertain  in 
its  effects  and  often  disappointing  in  its  results.  Perhaps  the  best  way 
to  influence  the  bacteria  of  the  large  intestines  is  through  diet.  A  pro- 
tein diet  favors  a  putrefaction  flora ;  a  carbohydrate  diet  a  normal  flora. 
Kendall,  in  his  work  on  intestinal  bacteriology,  has  shown  that  carbo- 
hydrates spare  proteins;  that  is,  bacteria  do  not  ordinarily  break  down 
protein  in  the  presence  of  carbohydrates. 

Putrid  Milk — Alkaline  Putrefaction. — When  boiled  milk  is  al- 
lowed to  stand  at  room  temperature,  it  gradually  acquires  an  alkaline 
reaction,^  a  bitter  taste,  and  finally  curdles,  yielding  a  soft,  slimy  curd. 

^  Schorer  found  that  such  milk  becomes  less  acid  but  seldom  becomes  actually 
alkaline  in  reaction. 


MILK  567 

On  further  standing  this  curd  is  peptonized  to  form  a  somewhat  clear 
fluid,  and  if  these  putrefactive  changes  are  allowed  to  proceed  for  a 
sufficient  length  of  time  a  semi-transparent  liquid  is  obtained,  having  no 
resemblance  to  milk.  In  this  form  of  decomposition  the  main  change 
occurs  in  the  protein  constituent  of  the  milk.  The  putrefactive  changes 
of  milk  are  undesirable  and  are  believed  sometimes  to  be  dangerous,  in 
that  toxic  substances  resembling  "ptomains"  ^  may  be  produced.  The 
principal  cause  of  putrefaction  in  milk  is  the  spore-bearing  group  of 
bacilli,  belonging  to  and  resembling  the  hay  bacillus  and  also  the  anae- 
robes. 

Slimy  or  Eopey  Milk. — Under  some  circumstances  certain  muci- 
laginous substances  develop  in  milk  through  abnormal  fermentation. 
Slimy  milk  has  been  obtained  of  such  viscosity  that  it  could  be  drawn 
out  into  threads  ten  feet  in  length,  and  of  such  thinness  as  to  be  scarcely 
visible.  In  Norway  such  milk  is  esteemed  a  delicacy;  in  this  country, 
however,  it  is  objectionable.  From  a  health  standpoint  ropey  milk  is 
not  injurious  unless  it  is  slimy  as  a  result  of  mucopurulent  materials 
caused  by  diseased  conditions  in  the  mammary  glands.  The  bacteria 
which  produce  ropey  milk  are  widely  distributed  in  nature.  Of  these 
B.  lactis  viscosis  (Adametz)  is  the  commonest  organism  found  in  Eu- 
rope, and  a  similar  organism  occurs  in  this  country.  B.  lactis  viscosis 
is  very  hardy;  it  may  find  its  way  into  the  milk  through  the  water 
supply  of  the  dairy,  and  then  becomes  widely  diffused  and  difficult  to 
trace.  It  is  sometimes  very  troublesome,  but  may  be  eradicated  through 
cleanliness.  Sometimes  it  is  necessary  to  resort  to  disinfection.  Other 
organisms  producing  sliminess  in  milk  are  the  Micrococcus  freuden-, 
reicliii,  two  forms  of  streptococci,  and  certain  of  the  lactic  acid  bacteria. 

Alcoholic  Fermentation  op  Milk. — This  is  an  abnormal  fermen- 
tation which  sometimes  occurs  as  a  result  of  yeasts,  aided  in  their  action 
by  certain  species  of  bacteria.  Alcoholic  fermentation  of  milk  seldom 
occurs  spontaneously,  but  may  be  induced  by  direct  inoculations  with 
certain  ferments,  such  as  those  employed  in  the  production  of  kumyss 
and  kefir. 

Kumyss  was  originally  made  from  mare's  milk;  is  now  made  from 
coVs  milk  by  the  addition  of  cane  sugar  and  yeast.  Kefr  is  a  similar 
beverage,  originating  in  the  Caucasus,  where  the  fermentation  is  carried 
out  in  leather  bottles  and  is  started  by  means  of  "kefir  grains"  which 
contain  yeast  and  various  microorganisms. 

Bitter  Milk. — Freshly  drawn  milk  sometimes  has  a  bitter  taste;  in 
other  instances  milk  acquires  such  a  taste  on  standing  a  few  hours. 
The  former  is  due  to  improperly  feeding  the  cow  with  such  herbs  as 
lupines,  wormwood,  raw  Swedish  turnips,  cabbages,  etc.  The  latter  case 
is  due  to  the  growth  of  certain  bacteria  in  the  milk  after  it  is  drawn. 

*See  page  528. 


568  ANIMAL  FOODS:  MILK 

The  condition  is  undesirable,  and  sometimes  causes  much  trouble  for  the 
dairyman,  but  it  has  no  particular  sanitary  significance.  According  to 
Conn,  it  is  a  micrococcus,  and  according  to  Weigmann  a  bacillus,  that 
has  the  power  of  ruining  the  taste  of  freshly  drawn  milk  in  a  few  hours. 
This  condition  should  be  distinguished  from  the  bitter  taste  of  putrid 
milk  above  noted. 

Colored  Milk. — Blue  milk  is  usually  due  to  the  Bacillus  cyanogenes. 
Such  milk  is  apparently  harmless.  Eed  milk  may  be  due  to  the  pres- 
ence of  blood  coming  from  an  injury,  or  acute  infection  of  the  udder. 
Sometimes  it  results  from  the  feeding  of  the  cow  on  plants  containing 
red  pigment,  such  as  the  madder  root.  A  red  color  may  also  be  pro-' 
duced  by  the  Bacilltis  erytlirogenes,  B.  prodigiosus  and  sarcinae.  Eed 
milk  caused  through  the  agency  of  bacteria  is  without  sanitary  sig- 
nificance. 

Adulterations  of -Milk. — Shimming. — The  removal  of  part  or  all  of 
the  cream  and  selling  the  remaining  fluid  as  whole  milk  is  an  economic 
fraud,  and  has  no  reference  to  health,  except  that  the  milk  is  cor- 
respondingly lowered  in  nutritive  value.  Adding  skim  milk  is  also  a 
form  of  adulteration  difficult  to  detect. 

Watering. — The  practice  of  watering  is  not  nearly  so  frequent  as 
formerly.  If  the  water  be  pure  it  must  be  regarded  more  as  a  fraud 
than  a  health  problem.  The  addition  of  water  to  milk  lowers  its  specific 
gravity,  raises  its  freezing  point,  and  lowers  its  index  of  refraction  and 
also  its  viscosity. 

Thickening  agents  such  as  the  use  of  chalk,  calves'  brain,  and 
glycerin,  have  never  been  common  practices.  Gelatin  or  lime  is  some- 
times used  to  thicken  cream.  Cream  may  also  be  thickened  by  homo- 
genizing it.  Coloring  matter  is  sometimes  added  with  the  object  of 
concealing  skimming  or  watering  or  to  make  the  milk  Ir  )k  richer. 
Annato,  a  vegetable  dye,  is  most  commonly  used;  orange  nd  yellow 
azo  coal-tar  are  also  used.  Allcalis,  such  as  sodium  carbon?  e  or  bicar- 
bonate, are  occasionally  added  to  milk  to  reduce  its  acidity  o  to  improve 
its  taste  or  to  delay  curdling.  Sweet  substances,  such  as  saccharin  or 
sugarj  are  occasionally  added  to  milk,  either  to  raise  the  specific  gravity 
and  thus  disguise  watering,  or  to  disguise  the  sour  taste  of  milk  just  on 
the  turn. 

Chemical  Preservatives. — Chemical  preservatives,  such  as  borax  and 
boracic  acid,  salicylic  acid,  benzoic  acid  and  benzoates,  potassium  bichro- 
mate, peroxid  of  hydrogen,  fluorids,  formaldehyd,  and  others,  have  from 
time  to  time  been  used  in  milk.  The  practice  of  adding  any  chemical 
preservative  to  milk  meets  with  the  unqualified  disapproval  of  the  sani- 
tarian. Almost  all  countries  prohibit  the  use  of  such  foreign  substances. 
The  only  proper  preservatives  for  milk  are  cleanliness  and  cold. 

Dirty  Milk — The  Dirt  Test. — Practically  all  milk  contains  more  or 


MILK 


569 


less  dirt.  For  the  most  part,  this  dirt  consists  of  cow  feces.  The  pres- 
ence of  dirt  may  best  be  determined  by  filtering  a  pint  of  milk  through 
a  little  disk  of  absorbent  cotton.  This  produces  a  stain  varying  in  inten- 
sity from  a  yellowish  to  a  brownish  or  black  spot.  A  Gooch  crucible, 
a  Lorenz  apparatus,  or  simply  an  ordinary  funnel  may  be  used  to  filter 
the  milk.  Warm  milk  filters  much  more  readily  than  cold  milk.  This 
simple  test  is  one  of  the  most  practical  of  the  routine  tests  used  for  the 
public  health  control  of  milk  supplies.  The  intensity  of  the  stain  and 
the  amount  of  deposit  upon  the  cotton  is  a  tell-tale  which  appeals  strongly 
to  farmers  and  dairymen,  as  well  as  to  consumers.  It  is  a  good  practice 
to  send  these  disks  of  cotton,  with  a  letter,  to  the  farmer,  showing  him 


Fig.  72. — Conditions  under  Which  It  Is  Difficult  to   Cleanse  and  Disinfect 
Milk  Bottles  and  Milk  Pails. 


the  amount  of  dirt  contained  in  his  milk.  The  disks  may  be  dried  and 
kept  with  the  records  of  the  health  office. 

It  should  be  remembered  that  milk  that  has  been  "clarified"  or 
strained  will  not  show  the  dirt  test. 

Bacteria  in  Milk. — As  a  rule,  milk  contains  relatively  and  actually 
more  bacteria  than  any  other  article  of  diet.  Milk  may,  in  fact,  con- 
tain more  bacteria  than  any  other  known  substance;  it  frequently  con- 
tains many  more  bacteria  than  are  found  in  sewage.  Mere  numbers, 
however,  need  not  alarm  us,  for  it  is  the  kind  that  most  concerns  us. 
By  universal  consent,  however,  milk  containing  an  excessive  number 
of  miscellaneous  bacteria  is  not  suitable  for  infant  feeding.  Were  milk 
a  transparent  food  the  enormous  growth  of  microorganisms  present  in 
average  market  milk  would  be  plainly  visible  to  the  naked  eye. 

The  bacteria  get  into  the  milk  from  a  number  of  different  sources. 


670  ANIMAL  FOODS:  MILK 

Some  of  them  are  in  the  milk  before  it  leaves  the  udder.  They  grow 
up  the  milk  ducts  into  the  milk  cistern;  hence,  the  fore-milk  contains 
more  than  the  mid-milk  or  strippings.  It  is  practically  impossible  to 
obtain  sterile  milk  directly  from  the  teat  in  any  large  quantity.  As 
soon  as  the  milk  leaves  the  teat  it  receives  additional  contamination 
from  all  objects  with  which  it  comes  in  contact,  as  the  hands,  the  pail, 
the  dust  in  the  air,  etc.  Most  bacteria  get  into  milk  with  the  dirt  that 
falls  from  the  belly  and  udder  of  the  cow  during  milking. 

The  number  of  bacteria  in  milk  increases  every  time  it  is  handled 
or  exposed  in  any  way.  Separator  milk  contains  more  bacteria  than  the 
original  milk.  The  same  is  true  of  filtered  milk.  This  is  due  to  the  fact 
that,  while  some  of  the  visible  dirt  in  the  milk  is  taken  out,  the  particles 
are  broken  up  and  the  bacteria  dispersed  throughout  the  fluid. 

Garget,  or  inflammation  of  the  udder,  is  a  very  common  affection  of 
cows,  and  is  associated  with  streptococci^  staphylococci,  paratyphoid,  ba- 
cilli, colon  bacilli,  etc.  Milk  from  a  gargety  udder  will  contain  enormous 
numbers  of  the  corresponding  microorganisms. 

For  the  most  part  bacteria  do  not  pass  a  healthy  udder.  However, 
we  can  place  no  trust  in  the  filtering  ability  of  the  mammary  gland.  It 
is  known  that  the  virus  of  foot-and-mouth  disease,  which  is  ultramicro- 
scopic,  and  the  virus  of  malta  fever  (Micrococcus  melitensis),  and  also 
the  virus  of  milk  sickness  are  almost  constantly  foimd  in  the  milk  of 
affected  animals.  On  the  other  hand,  tubercle  bacilli  do  not  pass  the 
mammary  gland  unless  there  is  tuberculosis  of  the  udder. 

The  bacteria  in  milk  are  not  equally  distributed  throughout  the 
fluid.  There  are  more  bacteria  in  cream  than  in  the  underlying  skim 
milk — particularly  in  gravity  cream.  As  the  cream  rises  it  mechanically 
carries  the  bacteria  along  with  it,  very  much  as  a  snowstorm  sweeps  the 
atmosphere.  Milk  formulae  for  infant  feeding  are  often  made  of  top 
milk,  which,  however,  may  contain  5  to  100  times  the  number  of  bacteria 
per  cubic  centimeter  found  in  the  whole  milk.  In  twenty-six  samples  of 
milk  Anderson  found  the  gravity  cream  contained  about  four  times  as 
many  bacteria  as  the  sediment  layer,  and  about  one-third  as  many  as  the 
whole  milk.  Schorer  found  that  the  cream  from  milk  of  high  bacterial 
count  contained  several  thousand  times  as  many  bacteria  as  the  under- 
lying skim  milk. 

Certified  milk  should  not  contain  over  10,000  bacteria  per  c.  c; 
inspected  milk  not  over  100,000,  and  market  milk  not  over  500,000. 
New  York  has  placed  the  limit  at  1,000,000  per  c.  c.  Even  this  stand- 
ard, however,  has  not  been  rigidly  enforced.  Boston  has  a  standard 
of  500,000;  Eochester  100,000. 

In  Washington  in  1908  the  average  bacterial  count  of  the  market 
milk  was  23,000,000  per  c.  c,  as  found  in  many  hundreds  of  samples  of 
the  city  supply.    In  1907  the  average  was  reduced  to  11,000,000. 


MILK  671 

Excessive  numbers  of  bacteria  in  milk  indicate  that  it  is  dirty,  old, 
or  warm.  Any  one  or  any  combination  of  these  factors  favors  a  rapid 
growth  and  multiplication  of  the  bacteria  in  milk. 

The  number  of  hacteria  in  milk  is  the  best  single  index  we  have  of  its 
general  sanitary  character. 

Methods  for  determining  the  number  and  kind  of  bacteria  in  milk 
will  be  found  on  page  588. 

The  Germicidal  Property  of  Milk. — The  so-called  germicidal  prop- 
erty of  milk  has  been  much  misunderstood.  Judged  by  the  number  of 
colonies  that  develop  upon  agar  plates,  the  bacteria  in  milk  first  dim- 
inish, then  increase  in  nimiber.  This  occurs  only  in  raw  milk  during 
the  first  8  or  13  hours  after  it  is  drawn.  Although  the  bacteria  seem- 
ingly decrease  in  numbers,  they  never  entirely  disappear.  After  this 
initial  decrease  there  is  a  continuous  and  rapid  increase,  until  the  milk 
contains  almost  infinite  numbers  in  each  cubic  centimeter.  This  power 
of  milk  to  restrain  the  development  of  bacteria  lasts  from  6  to  24:  hours, 
depending  upon  the  temperature  at  which  the  milk  is  kept.  When 
the  milk  is  kept  warm,  37°  C,  the  decrease  is  pronounced  within  the 
first  8  or  10  hours;  after  this  the  milk  has  entirely  lost  its  restraining 
action.  When  the  milk  is  kept  cool,  15°  C,  the  decrease  is  less  marked 
but  more  prolonged. 

The  decrease  in  the  number  of  bacteria  is  largely  apparent,  being 
due,  at  least  in  part,  to  agglutination ;  that  is,  the  bacteria  are  not  killed, 
they  are  simply  grouped  in  clusters ;  this  is  proven  by  the  fact  that  these 
clusters  may  be  shaken  asunder.  The  germicidal  action  of  milk  is 
specific;  at  most,  is  feeble,  and  is  destroyed  if  the  milk  is  heated  above 
80°  C.  It  varies  in  diflPerent  animals,  and  in  the  milk  from  the  same 
animal  at  different  times.  It  cannot  take  the  place  of  cleanliness  and  ice, 
but  may  be  taken  advantage  of  in  good  dairy  methods.  It  is  true  that 
bacteria  develop  more  quickly  in  heated  milk  than  raw  milk,  provided  the 
raw  milk  is  fresh;  it  should  be  remembered,  however,  that  milk  that  is 
a  day  old  no  longer  possesses  this  restraining  action.  The  germicidal 
property  is,  therefore,  ordinarily  absent  in  market  milk. 

Diseases  Spread  by  Milk. — The  diseases  most  commonly  conveyed 
through  milk  are:  tuberculosis,  typhoid  fever,  diphtheria,  scarlet  fever, 
septic  sore  throat,  malta  fever,  foot-and-mouth  disease,  and  milk  sickness, 
also  some  of  the  summer  complaints  of  children,  and  the  diarrheal  and 
dysenteric  diseases  of  adults,  which  are  often  referable  to  infected  milk. 

As  a  rule,  milk  becomes  infected  from  human  sources,  sometimes 
on  the  farm,  sometimes  at  the  dairy,  sometimes  in  transportation,  and 
occasionally  in  the  household.  Sometimes  the  milk  becomes  infected  as 
a  result  of  disease  of  the  cow,  as  in  the  case  of  bovine  tuberculosis,  malta 
fever,  foot-and-mouth  disease,  streptococci,  etc. 

When  all  the  facts  are  brought  together  they  make  a  strong  indictment 


573 


ANTMAL  FOODS:  MTLTv 


against  milk.    Thus,  during  the  five  years,  1907-11,  there  wore  five  milk- 
borne  outbreaks  in  Boston,  causing  a  total  of  over  4,000  cases  of  sickness. 


Year 


Milk-borne  Epidemics  in  Greater  Boston 


Cases 


1907 
1907 
1908 
1910 
1911 


Diphtheria 

Scarlet  fever 

Typhoid  fever,  about .... 
Scarlet  fever,  over ..'..... 
"Septic  sore  throat,"  over 


72 
717 
400 

842 
2,065 


1,096 


In  addition  to  the  specific  diseases,  milk  may  be  injurious  as  a  result 
of  other  causes.  Thus,  Le  Blanc  has  pointed  out  that  the  milk  of  cows 
in  heat  may  cause  gastrointestinal  disturbances.  The  toxic  effects  of  milk 
and  milk  products  of  nymphomanous  cows  are  even  more  marked.  Milk 
should  not  be  used  within  fifteen  days  of  parturition.  The  require- 
ment for  certified  milk  is  placed  at  thirty  days  before  and  fif- 
teen days  after.  Such  milk  is  apt  to  produce  diarrhea,  colic,  and 
other  digestive  disturbances.  Milk  may  further  be  harmful  as  a  result 
of  such  diseases  as  mastitis  or  garget,  gastroenteritis,  septic  and  febrile 
conditions  of  the  cow.  Eecently  it  has  been  shown  that  contagious  abor- 
tion of  cows  is  due  to  the  Bacillus  abortus,  which  may  contaminate  milk; 
it  is  pathogenic  for  many  animals,  probably  including  man.  Schroeder 
and  Cotton  found  this  bacillus  in  8  out  of  27  samples  of  market  milk 
tested.    All  such  milk  should  be  excluded  or  pasteurized. 

Tuberculosis. — Bovine  tubercle  bacilli  get  into  milk  either  directly 
as  a  result  of  tuberculosis  of  the  udder,  which  occurs  in  from  1  to  3 
per  cent,  of  all  tubercular  cows,  or  indirectly  through  cow  manure.  In 
the  latter  case  the  tubercle  bacilli  are  coughed  up,  swallowed,  and  passed 
in  the  feces.  Practically  all  market  milk  contains  cow  feces.  Occasion- 
ally milk  contains  tubercle  bacilli  of  the  human  type  from  human  sources. 
Tuberculosis  in  cattle  is  very  prevalent.  In  Holland  nearly  1/10  of 
all  cattle  killed  for  food  are  tuberculous;  in  Berlin  16  per  cent;  in  Sax- 
ony 30  per  cent;  in  Pennsylvania  from  2  to  3  per  cent.  The  '^milk'' 
from  a  tuberculous  udder,  when  examined  under  the  microscope,  may 
contain  as  many  tubercle  bacilli  as  are  ordinarily  found  in  tuberculous 
sputum.  The  milk  from  a  tuberculous  udder  of  one  cow  may  contain 
sufficient  bacilli  to  infect  the  milk  of  25  or  30  cows.  In  one  case  Ostertag 
found  that  0.001  c.  c.  of  the  secretion  from  a  tuberculous  udder  was 
sufficient  to  cause  tuberculosis  in  a  guinea-pig.  In  such  a  case  a  child 
would  receive  an  enormous  dose  in  a  gill. 

Tonney  examined  the  market  milk  of  Chicago  in  1910  for  the  presence 
of  tubercle  bacilli.  In  10.5  per  cent,  of  144  samples  of  raw  milk  he 
found  tubercle  bacilli  in  sufficient  numbers  to  infect  guinea-pigs.     Of 


MILK  573 

19  samples  of  pasteurized  milk  examined  none  contained  tubercle  bacilli. 

Hess  in  1909  examined  107  samples  of  market  milk  in  JSTew  York 
City,  with  the  result  that  17  of  them,  or  16  per  cent.,  were  found  to 
contain  tubercle  bacilli. 

Anderson  examined  223  samples  taken  in  the  city  of  Washington, 
and  reported  16,  or  6.72  per  cent.,  as  positive.  The  tests  made  by  the 
Bureau  of  Animal  Industry  of  the  milk  in  Washington  disclosed  7.7 
per  cent,  infected.  Goler  reports  about  5  per  cent,  of  the  milk  supply 
of  Kochester,  N.  Y.,  infected.  Sheridan  Delepine  ^  reports  that  the  mixed 
milk  of  Manchester,  Eng.,  collected  at  railway  stations  or  other  places 
than  the  farm,  contained  tubercle  bacilli,  as  follows  in  the  samples 
examined  from 

1897  to  1899 17.2  per  cent. 

1900  to  1904 10.3  per  cent. 

1905  to  1909 6.8  per  cent. 

1910  to  1913 9.0  per  cent. 

(years  are  inclusive) 

To  sum  up,  we  have  evidence  from  four  typical  American  cities. 
A  total  of  551  samples  of  milk  have  been  examined,  in  which  tubercle 
bacilli  were  found  in  46,  making  a  percentage  of  8.3.  This  may  be 
taken  as  the  average  percentage  for  the  entire  country. 

Professor  Delepine  found  that  the  milk  sent  by  rail  to  Manchester 
from  272  farms  contained  tubercle  bacilli  from  26,  or  9.5  per  cent. 
Wherever  these  investigations  have  been  carried  out  similar  and  some- 
times higher  results  have  been  obtained,  both  in  Europe  and  in  this 
country.  It  is  believed  that  the  figures  are  an  underestimate,  for  the 
methods  used  in  the  laboratory  are  not  sufficiently  delicate  to  detect 
a  few  tubercle  bacilli  in  milk.  Unless  these  microorganisms  are  pres- 
ent in  considerable  numbers,  they  are  apt  to  escape  detection.  In  any 
event,  it  is  clear  that  the  common  market  milk  furnished  all  large 
cities  and  probably  most  small  towns  very  often  contains  tubercle  bacilli. 

Mohler,  Washburn,  and  Doane  found  tubercle  bacilli  to  live  a  year 
and  more  in  cheese  220  days  old.  In  these  experiments  the  cheese  was 
purposely  infected  and  fed  or  inoculated  into  guinea-pigs  at  various 
times.     Tubercle  bacilli  are  frequently  found  in  butter  (page  580). 

The  relation  of  bovine  tuberculosis  to  man  is  considered  on  page  136. 

Method  of  Detecting  Tubercle  Bacilli  in  Milk. — It  is  not  a  simple 
matter  to  discover  tubercle  bacilli  in  milk,  butter,  and  similar  j^roducts. 
Direct  microscopic  examination  for  acid-fast  bacilli  is  not  satisfactory, 
because  ordinarily  there  are  comparatively  few  tubercle  bacilli  in  mixed 
market  milk,  and  furthermore,  many  acid-fast  microorganisms  other  than 
tubercle  bacilli  occur  in  milk. 

^Jour.  of  State  Med.  Rep.,  November   and  December,   1914. 


574  ANIMAL  FOODS:  MILK 

It  is  not  an  easy  task  to  isolate  tubercle  bacilli  in  pure  culture,  be- 
cause the  enormous  number  of  other  saprophytic  microorganisms  over- 
grow the  cultures.  Antiformin  may  be  tried  for  this  purpose  (see  page 
1160). 

It  therefore  becomes  necessary  to  resort  to  animal  experimentation 
in  order  to  isolate  tubercle  bacilli.  The  guinea-pig  is  the  most  susceptible 
and  suitable  animal  for  this  purpose.  The  material  under  examination 
may  be  injected  subcutaneously  or  intraperitoneally.  A  number  of  ani- 
mals should  be  inoculated  with  the  sample  in  question  for  the  reason  that 
a  certain  proportion  of  them  will  succumb  to  other  infections,  especially 
streptococci  or  members  of  the  hemorrhagic  septicemic  group,  which  are 
often  found  in  milk.  For  this  reason,  it  is  advisable  to  inject  as  little 
material  as  possible  for  the  purposes  of  the  test.  Less  will  be  required 
if  the  sample  is  the  milk  from  one-quarter  of  a  cow  than  from  the  mixed 
milk  of  a  herd. 

The  tubercle  bacilli  in  milk  may  be  first  concentrated  by  centrifuga- 
tion.  Some  of  them  will  fall  to  the  bottom  with  the  sediment,  others 
will  rise  with  the  cream,  being  enmeshed  and  carried  by  the  fat  globules. 
The  cream  and  sediment  may  then  be  injected  into  guinea-pigs,  either 
separately  or  mixed.  It  should  be  remembered  that  this  process  not  only 
concentrates  the  tubercle  bacilli,  but  other  microorganisms  that  may  be 
in  the  milk. 

The  sediment  may  first  be  treated  with  antiformin,  which  destroys 
many  of  the  frailer  cocci  and  bacilli,  but  spares  the  tubercle  bacilli. 
Antiformin  is  a  strong  alkalin  solution  of  chlorinated  soda  (see  page 
1030). 

The  guinea-pigs  that  survive  the  early  pathogenic  infections  that 
contaminate  the  milk  should  be  watched  for  symptoms  of  tuberculosis — 
enlarged  glands,  loss  of  weight  and  fever.  Those  that  do  not  die  in  two 
months  should  be  tested  with  tuberculin.  Inject  3  c.  c,  subcutaneously, 
of  Koch's  old  tuberculin.  This  must  be  diluted  back  to  the  original 
strength  of  the  bouillon  culture.  If  the  guinea-pig  is  tuberculous  it  will 
die  within  twenty-four  hours — usually  8  to  16 — with  characteristic 
lesions  of  reaction  about  the  tuberculous  foci. 

Typhoid  Fever. — Of  milk-borne  epidemics,  typhoid  fever  takes  the 
lead.  Typhoid  bacilli  may  swarm  in  milk  without  altering  its  taste, 
odor,  or  appearance.  In  Washington  10  per  cent,  of  all  the  cases  of 
typhoid  fever  during  the  four  years  1907-10  were  traced  to  milk.  The 
milk  may  become  infected  by  a  convalescent,  a  carrier,  or  a  missed  case. 

Bolduan  estimates  that  from  300  to  400  cases  of  typhoid  fever  each 
year  come  in  contact  with  the  milk  supplied  New  York  City.  He  fur- 
ther states  that  "the  startling  total  of  90  to  130  typhoid  carriers  now 
probably  menace  the  milk  supply  of  this  city."  This  estimate  is  based 
upon  the  fact  that  about  200,000  persons  come  into  more  or  less  con- 


MILK  575 

tact  with  the  milk  from  over  40,000  dairy  farms  (see  Typhoid  Fever, 
page  98). 

Milk-borne  outbreaks  of  paratyphoid  fever  have  been  described  by 
Levine  and  Elberson  ^  and  others. 

Scarlet  Fever. — Milk-borne  outbreaks  of"  scarlet  fever  are  some- 
times extensive  and  serious.  The  milk  is  practically  always  infected 
from  human  sources.  There  is  a  suspicion,  however,  that  some 
streptococcal  infections  of  the  cow  may  reproduce  a  disease  resembling 
scarlet  fever  in  man  (see  Scarlet  Fever,  page  181). 

Diphtheria. — Diphtheria  bacilli  in  milk  usually  come  from  human 
sources,  either  cases  or  carriers.  In  a  few  instances  ulcers  upon  the 
teat  of  the  cow  have  become  infected  with  diphtheria,  and  the  bacilli 
are  thus  transferred  to  the  milk.  Such  an  occurrence,  however,  is  un- 
usual. As  a  rule,  diphtheria  outbreaks  caused  by  infected  milk  are  more 
limited  both  as  to  numbers  and  area  than  milk-borne  outbreaks  of 
typhoid  or  scarlet  fever  (see  Diphtheria,  page  163). 

Septic  Sore  Throat. — The  first  milk-borne  outbreak  of  ^'septic 
sore  throat"  recognized  in  this  country  occurred  in  and  about  Boston 
in  May,  1911.  Since  then  similar  outbreaks  have  occurred  in  Balti- 
more, Concord,  IST.  H.,  Chicago,  and  elsewhere.  The  infection  is  spread- 
ing. The  Boston  outbreak  was  carefully  studied  by  Winslow  and  is  so 
instructive  that  a  brief  account  of  it  is  given  below. 

Septic  sore  throat  due  to  infected  milk  is  well  known  in  Great 
Britain.  Swithinbank  and  Newman  state  that  a  year  never  goes  by 
in  which  there  are  not  outbreaks  of  sore  throat  or  tonsillitis  due  to  milk 
or  cream.  These  infections  appear  to  be  due  to  a  streptococcus,  several 
varieties  having  been  isolated  both  from  the  milk  and  the  throats  of 
the  patients.  It  is  assumed  that  the  infection  usually  gets  into  the 
milk  from  human  sources,  although  it  is  suspected  that  streptococci 
eliminated  by  diseased  udders  may  be  responsible  for  some  outbreaks. 

The  work  of  Theobald  Smith  and  E.  H.  Brown  ^  on  the  streptococci 
of  septic  sore  throat  clears  up  the  etiology  and  modes  of  transmission 
of  this  infection.  These  workers  have  clearly  shown  that  there  is  a 
difference  between  bovine  and  human  streptococci,  a  distinction  of 
fundamental  importance,  comparable  to  Theobald  Smith's  pioneer  work 
upon  the  difference  between  bovine  and  human  tubercle  bacilli. 

The  bovine  streptococci  produce  garget  in  cows  but  do  not  cause 
tonsillitis  in  men;  on  the  other  hand,  the  human  streptococci  produce 
sore  throat  in  man  but  have  slight  pathogenicity  for  cows.  The  human 
streptococci  are  alike  in  two  characteristics:  (1)  the  colonies  produce 
immediately  around  them  a  clear  hemolized  zone  on  blood  agar  plates 

^Journal  of  Infectious  Diseases,  Feb.,  1916,  Vol.  18,  No.  2,  p.  143. 
''Jour,   of  Med.  Res.,    1915,   XXXI,   p.   455.     Also   W.    G.   Smillie,   "On   the 
Streptococcus  of  Theobald  Smith,"  Journal  of  Infectious  Diseases. 


576  ANIMAL  FOODS:  MILK 

(horse  blood) ;  (2)  these  organisms  ferment  salicin  but  not  raffinose  or 
inulin.  Further  they  are  pathogenic  when  injected  into  rabbits.  These 
organisms  are  called  by  Smith  and  Brown  the  Beta  type,  but  will  here- 
after doubtless  be  known  as  the  Theobald  Smith  streptococci. 

Smith  and  Brown  studied  the  streptococci  from  five  milk-borne 
epidemics  at  first  hand,  together  with  cultures  from  the  big  epidemics 
of  Chicago,  Baltimore  and  Boston.  From  this  work  it  is  now  clear  that 
septic  sore  throat  in  man  is  of  human  origin,  even  M'hen  the  disease  is 
contracted  through  infected  milk.  However,  it  was  found  that  while 
the  human  streptococcus  is  but  slightly  pathogenic  for  cows,  this 
organism  may  become  implanted  in  the  udder.  This  may  take  place 
through  milking,  wiping  with  infected  cloths,  through  passing  quills  up 
the  milk  ducts  and  in  similar  ways.  When  this  takes  place,  garget  does 
not  ensue  but  the  streptococcus  becomes  seeded  in  the  udder  and  may 
remain  for  six  weeks  or  longer.  In  other  words  the  cow  may  become  a 
"carrier"  of  the  human  streptococcus,  thus  explaining  why  milk-borne 
outbreaks  of  septic  sore  throat  are  sometimes  long  drawn  out. 

The  disease  often  presents  a  severe  clinical  type  and  may  result  in 
death.  Apparently  it  is  not  readily  communicable  from  person  to  person. 
The  inflammation  and  swelling  of  the  lymphoid  structures  of  the  throat 
and  of  the  mucous  membranes  are  more  severe  than  ordinarily;  edema 
is  a  feature,  and  many  cases  present  pseudomembranous  formation  and 
other  indications  of  a  virulent  infection.  There  is  a  sharp  febrile  re- 
action, prostration,  and  sometimes  delirium.  The  duration  of  the  disease 
may  be  prolonged,  and  complications  occur  in  about  one-quarter  of  the 
cases.  These  consist  mostly  of  enlarged  regional  lymph  nodes,  which 
may  suppurate;  abscesses,  arthritis,  endocarditis,  peritonitis,  erysipelas, 
pneumonia,  pyemia,  acute  nephritis,  otitis,  and  other  sequelae  indicating 
the  invasion  of  the  blood  with  a  virulent  streptococcus. 

The  Boston  outbreak  in  1911  was  characterized  by  its  extraordinary 
virulence  and  comparative  immunity  of  children,  and  high  mortality 
among  the  aged  and  infirm.  In  this  outbreak  there  were  over  3,000 
cases  with  about  48  deaths.  One  of  the  features  of  special  interest  was 
that  the  milk  incriminated  had  always  been  a  particularly  clean,  fresh, 
and  satisfactory  supply.  It  was  obtained  from  tuberculin-tested  cows 
under  veterinary  supervision,  and  the  milk  itself  subjected  to  frequent 
chemical  and  bacteriological  tests.  The  milk  was  bottled  at  the  dairy, 
the  bottles  were  sterilized,  and  many  extra  precautions  were  taken  to 
ensure  its  cleanliness.  For  28  years  not  a  breath  of  suspicion  was  at- 
tached to  this  milk  until  this  catastrophe  occurred.  It  emphasizes  the 
lesson  that  raw  milk  is  apt  to  be  dangerous  milk,  and  our  only  protec- 
tion against  these  particular  dangers  is  through  pasteurization.^ 

*  For   a   more   detailed   study  of  this   and   other  milk-borne   outbreaks   see 
"The  Milk  Question,"  by  M.  J.  Rosenau. 


MILK  577 

Milk  Sickness. — Slows  or  trembles  is  a  peculiar  disease  found 
in  the  central  part  of  the  United  States.  As  forests  are  cleared  and 
pastures  fenced  the  disease  becomes  less  frequent.  It  is  still  met  with 
in  the  valley  of  the  Pecos  Eiver,  New  Mexico,  in  parts  of  Tennessee 
and  North  Carolina.  The  virus  is  communicated  to  man  and  is  fre- 
quently fatal.  Nancy  Hanks,  the  mother  of  Lincoln,  died  from  the 
disease  in  1818  after  an  illness  of  a  week.  Little  is  known  of  the 
cause  of  milk  sickness.  Jordan  and  Harris  have  found  a  bacillus 
associated  with  the  disease  which  they  have  called  the  Bacillus  lactis 
morhi. 

Milk  sickness  is  an  acute  non-febrile  disease  due  to  the  ingestion  of 
milk,  milk  products,  or  the  flesh  of  animals  suffering  from  a  disease 
known  as  trembles.  The  disease  is  characterized  by  great  depression, 
persistent  vomiting,  obstinate  constipation,  and  high  mortality. 

Malta  Fevek. — Malta  fever  is  a  disease  primarily  of  goats;  sec- 
ondarily of  man.  The  infection  is  transmitted  from  goats  to  man 
through  milk  containing  the  Micrococcus  melitensis  (see  page  321). 

FooT-AND-MouTH  DISEASE. — Foot-and-mouth  disease  is  an  infection 
primarily  of  cattle  and  secondarily  of  man.  It  is  caused  by  a  filtrable 
virus,  and  is  noteworthy  for  being  the  first  ultramicroscopie  virus  dis- 
covered by  Loeffler  and  Froseh  in  1898.  The  infection  is  transmitted  to 
man  through  the  ingestion  of  raw  milk,  buttermilk,  cheese,  or  whey 
from  diseased  cows.  Children  are  not  infrequently  infected  by  drinking 
unboiled  milk  when  the  disease  is  prevalent  in  the  neighborhood.  In 
man  the  disease  is  mild;  the  symptoms  resemble  those  observed  in 
animals;  there  is  fever,  sometimes  vomiting,  painful  swallowing,  heat 
and  dryness  of  the  mouth,  followed  by  an  eruption  of  vesicles  in  the 
buccal  and  mucous  membranes,  and  very  rarely  by  similar  ones  on  the 
fingers.  The  vesicles  are  about  the  size  of  a  pea;  they  soon  break, 
leaving  small  erosions,  which  rapidly  heal.  The  disease  is  seldom  fatal 
except  occasionally  in  very  weak  children  (see  page  317). 

Infantile  Diarrheas. — One  of  the  chief  causes  of  the  high  infant 
mortality  is  summer  diarrheas,  but  even  these  are  not  all  due  to  stale, 
dirty,  and  bacteria-laden  milk.  Many  of  the  diarrheal  diseases  of 
infancy  are  true  cases  of  baeillary  dysentery,  which  is  transmitted  in  a 
great  variety  of  ways.  However,  the  improvement  in  the  milk  supply 
for  babies  has  directly,  and  in  a  large  part  indirectly,  resulted  in  a 
decrease  in  infant  mortality  in  recent  years.  In  other  words,  improve- 
ment in  infant  mortality  is  almost  wholly  attributable  to  lessened 
diarrheal  diseases  in  the  summer  months.  Little  impression  has  yet 
been  made  upon  the  other  causes  of  infant  mortality. 

The  Character  of  Milk-borne  Epidemics. — Milk-borne  epidemics 
usually  have  an  explosive  onset,  rise  to  a  peak,  and  decline  gradually. 
The  character  of  the  curve  depends  upon  the  amount  of  infection  in 
20 


578 


ANIMAL  FOODS:  MTLK 


the  milk,  and  the  manner  of  its  distribution,  the  number  of  persons  who 
drink  it,  and  other  factors.  If  the  infection  in  the  milk  is  dilute  or 
attenuated,  the  disease  crops  out  among  a  few  susceptible  persons  who 
drink  it.  If  the  infection  is  concentrated  and  the  milk  is  widely  used, 
the  curve  of  the  outbreak  will  have  the  steeple-like  character  of  a  water- 
borne  epidemic.  The  length  of  the  epidemic  varies  with  the  period  of 
incubation  of  the  disease  and  with  the  length  of  time  the  milk  is  infected. 
The  number  of  people  involved  may  vary  from  a  few  to  a  hundred  or 
several  thousand.  Only  a  single  bottle  of  milk  may  be  infected,  and 
thus  convey  the  disease  to  only  one  person;  on  the  other  hand,  many 


Fig.  73. — ^A  Dark,  Poorly  Ventilated  Cow  Shed,  Difficult  to  Keep  Clean. 


gallons  of  mixed  dairy  milk  may  become  infected  and  produce  disease 
i  n  many  hundred  persons.  As  a  rule,  milk  outbreaks  last  a  comparatively 
short  time,  and  extend  over  a  circumscribed  area,  as  the  disease  follows 
the  milk  route.  At  first  the  disease  occurs  almost  exclusively  among  users 
of  the  infected  milk.     Afterward  secondary  cases  may  occur. 

The  disease  shows  a  special  incidence  among  milk  drinkers.  It  is 
interesting  to  note  that  sometimes  only  one  person  of  a  number  living 
in  the  same  house  is  attacked,  and  such  a  one  is  a  person  who  drinks 
the  milk  raw. 

Milk-borne  diseases  attack  those  living  under  the  best  sanitary  con- 
ditions. The  reason  for  this  is  that  such  people  drink  milk  more  freely 
than  the  poor.  Milk  outbreaks  among  the  well-to-do  are  unnecessary 
tragedies  to  the  sanitarian. 

Most  milk  outbreaks  show  a  greater  incidence  of  the  disease  amonsf 


MILK  579 

women  and  children,  who  are  usually  credited  with  drinking  more  milk 
than  men.  There  is  apt  to  be  a  short  period  of  incubation,  probably 
on  account  of  the  concentration  and  large  amount  of  the  infection; 
however,  the  disease  often  runs  a  mild  course.  Multiple  cases  occur 
simultaneously  in  the  same  house.  Such  an  occurrence  is  very  suggestive 
to  the  epidemiologist,  and  frequently  gives  him  the  first  hint  of  an  im- 
pending milk  epidemic. 

Desiccated  Milk. — Mr.  Gail  Borden  successfully  evaporated  milk  at  a 
low  temperature  under  reduced  pressure,  and  in  1856  obtained  a  patent 
for  his  process  of  preparing  "condensed'^  milk.  The  presence  of  the  fat 
has  interposed  the  greatest  difficulty  to  the  complete  drying  of  milk. 
Three  successful  processes  are  now  in  use:  (1)  In  the  Ekenberg  process 
the  milk  is  sprayed  under  constant  pressure  on  the  inner  surface  of 
a  rotating  steam-heated  cylinder.  The  milk  is  thus  dried  in  partial 
vacuum  at  a  comparatively  low  temperature.  (2)  A  more  frequently 
employed  process  common  in  the  production  of  cheaper  grades  consists 
in  spraying  the  previously  concentrated  milk  on  the  exterior  highly  pol- 
ished surface  of  revolving  steel  drums.  Here  it  is  almost  instantaneously 
dried  at  a  temperature  of  230°  F.  and  then  scraped  off  by  sharp  knife 
blades.  (3)  In  the  Benevot-de-Neveu  process  the  milk  is  first  concen- 
trated in  a  vacuum  and  then  sprayed  under  great  pressure  into  a  large 
drying  chamber  where  the  cloud  of  finely  atomized  particles  is  sur- 
rounded by  a  current  of  hot  air,  and  thereby  instantly  dried.  The  result 
is  a  powder  in  which  many  of  the  physical  and  chemical  properties  of 
the  original  milk  are  retained. 

Condensed  Milk. — Unsweetened  condensed  milk  must  be  sterilized, 
otherwise  it  will  not  keep.  The  sugar  preserves  the  sweetened  product, 
which  is  therefore  frequently  not  sterilized  and  contains  great  numbers 
of  bacteria — millions  per  cubic  centimeter.  At  the  prevailing  prices 
condensed  milk  is  expensive  when  nutritive  values  are  compared  to  fresh 
milk.  Babies  raised  on  condensed  milk  are  liable  to  develop  scurvy 
unless  given  orange  juice  or  other  anti-scorbutic  food. 

Fresh  Milk  Products. — Cream,  butter,  buttermilk,  ice-cream,  sour 
milk,  fresh  cheese,  and  other  milk  products  may  convey  all  the  infec- 
tions contained  in  the  original  milk  from  which  they  are  prepared.  It  is 
known  that  tubercle  bacilli  pass  into  butter  and  may  live  there  for 
months.  It  has  also  been  demonstrated  that  infected  cream  may  be 
the  cause  of  typhoid  fever,  septic  sore  throat,  and  without  doubt  diph- 
theria, scarlet  fever,  and  other  milk-borne  diseases. 

Milk  products  are  frequently  made  from  the  left-over  milk  or  milk 
otherwise  unsalable.  This  should  be  coiitrolled  by  an  efficient  system  of 
inspection. 

The  infections  in  fresh  milk  products  may  be  guarded  against  by 
pasteurization.     It  is  comparatively  easy  to  pasteurize  cream,'  for  the 


580  ANIMAL  FOODS:  MILK 

reason  that  it  may  be  heated  to  a  higher  temperature  than  is  the  case 
with  milk  without  materially  altering  its  physical  properties. 

For  so-called  tyrotoxicon  poisoning  due  to  cheese  see  section  on 
Ptomains. 

Butter. — Butter  is  made  from  "gravity"  cream  or  "separator"  cream. 
The  cream  may  be  fresh,  but  is  usually  ripened,  that  is,  partially  sour 
before  it  is  made  into  butter.  Special  cultures  of  microorganisms 
("starters")  are  sometimes  added  to  ripen  the  cream  for  the  purpose 
of  giving  the  butter  a  particular  flavor. 

Butter  is  usually  "scored"  in  accordance  with  a  score  card  proposed 
by  Woll  in  which  45  points  are  allowed  for  flavor,  25  for  grain  (body), 
15  for  color,  10  for  salt,  and  5  for  packing.  The  amount  of  fat  con- 
tained in  butter  may  be  determined  by  the  Doran  method  which  is 
accurate  to  within  one-half  per  cent.  Warm  the  butter  to  40°  C,  stir 
thoroughly,  add  about  10  c.  c.  of  the  sample  into  a  graduated  sedimenta- 
tion tube,  and  whirl  in  the  centrifuge  for  a  few  seconds;  measure,  and 
record.  Kow  add  about  5  c.  c.  of  gasoline;  mix,  and  whirl  again  for 
15  or  20  seconds.  The  gasoline  dissolves  the  fat  which  rises.  The  non- 
fat portion  sinks  to  the  bottom.  The  latter  is  measured  and  the  differ- 
ence represents  the  amount  of  fat.  The  United  States  regulations  re- 
quire that  butter  shall  not  contain  less  than  82.5  per  cent,  of  milk- 
fat,  and  a  renovated  butter  shall  not  contain  more  than  16  per  cent, 
of  moisture. 

Natural  butter  has  a  refractometer  index  at  40°  C,  ranging  from 
1.4531  to  1.4562,  usually  about  1.4553.  The  presence  of  other  fats  that 
have  been  mixed  with  the  butter  may  readily  be  determined  by  a  higher 
refractometer  reading.  Coloring  matter  is  often  added  to  butter.  The 
presence  of  coloring  matter  may  be  detected  by  dissolving  the  fat  in 
ether  and  adding  to  separate  portions  dilute  hydrochloric  acid  and 
sodium  hydroxid.  The  first  demonstrates  the  presence  of  the  azo  dyes, 
the  second,  the  vegetable  dyes. 

Butter  turns  acid  and  rancid  in  time,  owing  to  the  conversion  of 
the  fat  into  fatty  acids.  Eancid  butter  may  be  renovated  by  washing 
it  with  skim  milk  or  with  water,  to  which  bicarbonate  of  soda  or  lime 
is  sometimes  added  to  neutralize  the  acidity.  There  is  no  particular 
health  objection  to  these  processes  provided  such  butter  is  sold  as  reno- 
vated butter. 

Fresh  butter  contains  a  great  number  of  microorganisms  (millions 
per  gram).  The  total  bacterial  count  diminishes  with  time.  There 
may  be  a  reduction  of  85  per  cent,  in  two  weeks,  and  93  per  cent,  in 
four  weeks.  Butter  may  contain  tubercle  bacilli,  typhoid,  and  other 
pathogenic  bacilli.    Of  21  samples  of  market  butter  examined  in  Boston,' 

^Rosenau,  Frost  and  Bryant,  Jo%ir.  of  Med.  Res.,  XXX,  No.  1,  p.  69  i  March, 
1914, 


MILK  581 

two  of  them  were  found  to  contain  tubercle  bacilli,  being  9.5  per  cent,  of 
the  samples  examined.  On  account  of  this  danger  butter  should  always 
be  made  from  pasteurized  cream  and  labeled  "butter  made  from  pas- 
teurized cream,"  not  "pasteurized  butter/' 

Petri  examined  103  samples  of  butter  at  Berlin  using  408  animals 
for  inoculation;  16.7  per  cent,  contained  tubercle  bacilli.  Korn  found 
33.5  per  cent,  of  17  samples  of  butter  at  Freiberg  to  contain  tubercle 
bacilli. 

The  frequency  with  which  tubercle  bacilli  are  found  in  butter  is 
shown  in  a  table  collected  by  Swithinbank  and  Newman.^  Of  498  sam- 
ples tested  from  different  sources,  76,  or  15.3  per  cent.,  contained  tubercle 
bacilli. 

Schroeder  and  Cotton  ^  have  found  that  living  tubercle  bacilli  will 
retain  their  infective  properties  for  at  least  160  days  in  salted  butter 
when  kept  without  ice  in  a  house  cellar. 

Oleomargarine  is  a  mixture  of  various  animal  and  vegetable  fats 
and  oils  otherwise  used  as  food  products,  therefore  the  objections  to  the 
use  of  oleomargarine  are  more  on  the  grounds  of  fraud  and  deception 
than  in  regard  to  nutritive  value  or  sanitary  significance.  The  fraud 
consists  in  selling  oleomargarine  as  butter. 

In  the  United  States  the  manufacture  of  oleomargarine  can  take  place 
only  under  the  supervision  of  the  internal  revenue:  all  oleomargarine 
artificially  colored  to  resemble  butter  pays  an  internal  revenue  tax  of 
10  cents  per  pound;  uncolored,  i/4  of  a  cent  per  pound.  During  the 
fiscal  year  ending  June  30,  1910,  the  quantity  of  colored  oleomargarine 
manufactured  in  United  States  amounted  to  3,491,978  pounds;  and  un- 
colored, 85,164,655  pounds.  For  coloring  matter  anilin  dyes  are  usually 
preferred  to  annato  or  saffron. 

Oleomargarine  consists  of  a  mixture  of  neutral  lard,  beef  fat,  and 
cotton  seed  oil  which  are  usually  churned  with  milk  in  order  to  give  a 
flavor  of  butter  to  the  product.  The  yolk  of  eggs  and  other  substances  are 
sometimes  added.  In  the  manufacture  of  oleomargarine,  fat  from  the 
mesentery  and  mediastinum  is  said  to  be  sometimes  employed,  and  this 
fat  often  contains  tuberculous  glands.  The  milk  used  may  also  contain 
tubercle  bacilli.  Morgenroth  examined  SO  samples  of  oleomargarine,  some 
of  which  were  of  the  cheap  variety  and  some  expensive.  In  9  specimens 
tubercle  bacilli  were  found. 

Test  to  Distinguish  Butter  from  Oleomargarine. — Place  a  piece  of  the 
sample,  about  the  size  of  a  small  chestnut,  in  an  ordinary  tablespoon.  In 
the  laboratory  a  small  dish  or  test  tube  may  be  used.  Heat  over  a  flame, 
first  melting  the  sample  to  be  tested,  hastening  the  process  by  stirring 
with  a  splinter  of  wood   (a  match-stick).     When  melted,  increase  the 

1  "Bacteriology  of  Milk,"  p.  221. 

'Bureau  of  Animal  Industry  Cir.  No.  153,  p.  38. 


583  ANIMAL  FOODS:  MTLK 

heat,  bring  to  a  brisk  boil,  and  after  the  boiling  has  begun  stir  thoroughly, 
not  neglecting  the  outer  edges. 

Oleomargarine  and  renovated  butter  boil  noisily,  sputter  more  or 
less  like  a  mixture  of  grease  and  water  when  boiling,  and  produce  no 
foam,  or  very  little.  Eenovated  butter  produces  usually  a  very  small 
amount.  On  the  other  hand,  genuine  butter  boils  usually  with  less  noise 
and  produces  an  abundance  of  foam. 

The  refractometer  reading  gives  a  more  accurate  test  (see  page  598). 

Inspection. — An  efficient  inspection  service  is  a  preventive  measure 
that  strikes  at  the  root  of  the  milk  problem.  A  good  inspection  service 
is  expensive,  but  is  worth  its  cost  in  providing  cleaner  and  better  milk. 
Inspection  has  its  limitations,  for  it  cannot  see  bacillus  carriers,  mild 
cases  of  disease,  and  cannot  be  on  hand  at  all  places  at  all  times.  No 
system  of  inspection  can  be  so  perfect  as  to  insure  milk  free  from  in- 
fection at  all  times. 

A  competent  system  of  inspection  will  help  the  farmer  very  much 
with  his  problems,  and  the  educational  value  of  such  a  system  is  one 
of  its  best  features.  The  score-card  system  is  an  essential  element  in 
a  successful  inspection  service. 

The  score  card  should  be  used  in  inspecting  dairies,  but  dairy  scores  do 
not  correspond  to  milk  grades  as  determined  by  bacteriologic  tests. 

Inspection  is  particularly  helpful  in  tracing  the  source  of  infected 
milk  and  preventing  recurrences.  Another  important  element  in  any 
inspection  system  is  the  license  or  permit.  All  persons  producing  or 
handling  milk  should  obtain  a  license,  which  should  be  issued  only 
after  the  person  has  demonstrated  his  capacity  to  handle  milk  in  a  safe 
and  cleanly  manner. 

Pasteurization. — Pasteurization  as  applied  to  milk  consists  in  heating 
it  for  a  short  period  of  time  at  a  temperature  below  the  boiling  point, 
followed  by  rapid  chilling.  In  the  language  of  the  kitchen,  pasteurization 
means  parboiling.  To  the  sanitarian  pasteurization  has  but  one  object, 
viz.,  the  destruction  of  pathogenic  bacteria. 

Milk  heated  to  60°  C.  and  held  at  that  temperature  for  20  minutes 
will  kill  the  viruses  of  tuberculosis,  typhoid  fever,  scarlet  fever,  diph- 
theria, malta  fever,  dysentery,  foot-and-mouth  disease;  this  time  and 
temperature  will  also  kill  streptococci,  staphylococci,  and  practically  all 
non-spore-bearing  microorganisms  pathogenic  for  man.^  To  provide  a 
factor  of  safety  it  is  advisable  in  commercial  practice  to  heat  milk  to 
65°  C.  for  a  period  of  30  or  45  minutes.    Heating  milk  to  this  tempera- 

^De  Jong-  and  De  Graef  (quoted  by  Rullman,  Centralhl.  f.  Bahteriol.,  Part 
2,  1914,  XLI,  269)  have  described  seven  strains  of  B.  coli  which  survive  65° 
to  67°  C.  for  30  minutes  in  milk  or  broth.  These  strains  would  not  be  killed 
by  the  degree  of  heat  commonly  used  in  pasteurization  and  in  consequence  the 
presence  of  B.  coli  in  pasteurized  milk  can  no  longer  be  taken  as  an  index  of 
improper   pasteurization   or   subsequent   contamination. 


MILK  583 

ture  does  not  alter  its  taste,  odor,  or  digestibility,  does  not  interfere 
with  its  food  value,  and  has  the  great  advantage  of  preventing  much 
sickness  and  saving  many  lives. 

Pasteurization  is  not  the  ideal,  but  only  a  temporary  expedient. 
It  is  the  simplest,  cheapest,  least  objectionable,  and  most  trust- 
worthy method  of  rendering  infected  milk  safe.  Pasteurization, 
however,  cannot  atone  for  filth  and  should  not  be  used  as  a  re- 
demption process.  A  pure  milk  is  better  than  a  purified  milk; 
however,  no  one  should  drink  raw  milk  that  cannot  be  guaranteed 
by  the  health  officer  as  safe  and  free  from  danger.  Only  certified 
milk  or  milk  of  equally  high  character  can  be  regarded  as  rea- 
sonably safe  and  satisfactory  without  pasteurization.  Less  than  1 
per  cent,  of  all  the  milk  found  upon  the  market  comes  within  the 
honor  class. 

Pasteurized  milk  must  be  handled  at  least  as  carefully  as  raw  milk. 
It  should  be  bottled  by  machinery  immediately  following  the  process, 
kept  cold,  and  delivered  promptly.  Pasteurized  milk  sours  as  a  result 
of  acid  fermentation,  just  as  raw  milk  does.  In  other  words,  the  tem- 
peratures recommended  do  not  destroy  "nature's  danger  signal" — the 
lactic  acid  bacteria.^ 

Pasteurization  is  not  proposed  as  a  substitute  for  inspection,  but 
as  an  adjunct  to  inspection.  Inspection  gives  us  cleaner  and  better,  but 
not  necessarily  safe,  milk.  Pasteurization  eliminates  the  dangers  in- 
spection cannot  see.  The  combination  of  inspection  and  pasteurization 
corresponds  in  all  respects  to  modern  methods  of  obtaining  a  safe  water 
supply  for  a  large  city.  The  watershed,  through  inspection,  is  kept 
clean,  but  the  water  is  filtered  or  purified  before  it  is  given  to  the  con- 
sumer. 

There  can  be  no  more  objection  to  the  heating  of  milk  for  the  use 
of  adults  and  children  above  the  age  of  three  years  than  there  is  to  the 
cooking  of  meat.  Infants  should  receive  breast  milk.  When  this  is 
not  possible  they  should  have  the  best,  freshest  cow's  milk  that  can  be 
obtained.  Whether  such  milk  is  to  be  pasteurized,  modified,  or  other- 
wise treated  will  vary  with  circumstances. 

Much  has  been  said  concerning  the  relation  of  scurvy  and  rickets 
to  pasteurized  milk.  This  is  still  a  disputed  point,  but  the  evidence 
seems  clear  to  me  that  these  two  diseases  bear  no  relation  whatever  to 
the  heating  of  the  milk.  Scurvy  may  readily  be  prevented  by  the  use 
of  a  little  orange  juice,  pineapple  juice,  or  the  juice  of  other  fresh 
fruits.  Pickets  is  a  disease  of  defective  alimentation,  which  cannot  be 
laid  to  the  door  of  pasteurization.  Pediatricians  now  almost  unani- 
mously recommend  pasteurization,  particularly  in  the  summer  time,  es- 

*  Nature  has  no  danger  signal  for  infected  milk.  Pathogenic  micro-organ- 
isms do  not  alter  the  taste,  odor  or  appearance  of  milk. 


584 


ANIMAL  FOODS:  MILK 


pecially  for  those  infants  who  must  depend  upon  ordinary  market  milk 
or  milk  of  unknown  quality. 

Pasteurization  is  too  important  a  public  health  measure  to  leave  to 
individual  caprice.  The  process  should  be  under  official  supervision. 
Further,  pasteurized  milk  should  be  labeled  as  such  or  simply  "heated 

milk,"  stating  the  degree 
of  heat  and  the  length  of 
time,  and  the  date  on 
which  the  process  was 
done. 

Pasteurization  is  some- 
times objected  to  because  it 
does  not  destroy  heat-re- 
sisting toxines  which  are 
supposed  to  be  in  milk. 
The  occurrence  of  such 
poisons  is  a  mere  assump- 
tion. Even  if  they  exist  in 
milk  they  would  be  in  the 
raw  milk  as  well  as  in  the 
heated  milk.  The  true 
exotoxins  are  all  killed  at 
60°  C.  for  20  minutes. 

Theoretically  the  best 
place  to  pasteurize  milk  is 
in  the  home.  Practically 
the  best  place  is  at  some 
central  station,  where  it 
may  be  done  scientifically  under  official  surveillance. 

Methods  of  Pasteurization. — There  are  three  well-known  methods 
by  which  milk  may  be  pasteurized:  (1)  the  flash  method;  (2)  the 
holding  method;  (3)  in  the  bottle. 

The  flash  method  consists  of  heating  the  milk  momentarily  to  a 
temperature  of  about  178°  F,  and  chilling  it  at  once.  This  method  is 
sometimes  incorrectly  called  commercial  pasteurization.  It  does  not 
give  uniform  results,  is  not  entirely  reliable,  and  does  not  meet  with 
the  approval  of  the  sanitarian.  The  method,  however,  is  rapid,  cheap,  and 
much  in  vogue. 

The  holding  method  consists  in  heating  the  milk  to  the  desired 
temperature,  say  65°  C,  and  then  holding  it  in  a  suitable  tank  or  series 
of  tanks  at  that  temperature  for  a  given  period  of  time,  say  30  or  45 
minutes.  This  method  has  proven  satisfactory  in  practice  under  com- 
mercial conditions. 

Pasteurization  in  the  bottle  is  the  perfection  of  the  art.     It  is  the 


^ 

"x 

y^  ;•  7'<st 

\^ 

MM  l" 

m 

pv  ' 

{H 

1^                           / 

/)' 

'/ 

/'/' 

/ 

^pHii^^- 

^1^   ^ 

^ma»'                ^^^Httk 

Fig.  74. — ^Automatic  Temperature  Recorder  for 

Pasteurizers. 


MILK 


585 


ideal  method,  because  the  danger,  however  slight,  of  recontamination 
is  entirely  eliminated.  In  order  to  pasteurize  milk  in  bottles  the  bottles 
must  be  well  sealed  with  a  tight  cork  and  cap,  or  equally  effective 
stopper.  The  bottles  containing  the  milk  may  either  be  immersed  in 
a  water  bath,  brought  to  the  proper  temperature,  held  there  a  sufficient 
length  of  time,  and  then  chilled ;  or  the  methods  used  in  beer  pasteuriza- 
tion, such  as  the  Loew  pasteurizers,  may  be  used.  In  this  case  the 
bottles  are  subjected  to  a  spray  or  shower  of  heated  water. 


Fig.  75. — Straus  Home  PASTEji.jziii4 


Freeman's  pasteurizer  for  heating  milk  in  individual  feeding  bottles 
in  the  home  is  most  serviceable.  The  modification  of  Mr.  Nathan  Straus 
is  shown  in  Fig.  75.    It  is  used  as  follows: 

After  the  bottles  have  been  thoroughly  cleaned  they  are  placed  in 
the  tray  (A)  and  filled  with  the  milk  or  mixture  used  for  one  feeding. 
Then  put  on  the  corks  or  patented  stoppers  without  fastening  them 
tightly. 

The  pot  (B)  is  now  placed  on  the  wooden  surface  of  the  table  or 
floor  and  filled  to  the  supports  (C)  with  boiling  water.  Place  the  tray 
(A)  with  filled  bottles  into  the  pot  (B)  so  that  the  bottom  of  the  tray 
rests  on  the  supports  (C),  and  put  cover  (D)  on  quickly. 

After  the  bottles  have  been  warmed  up  by  the  steam  for  five  minutes, 
remove  the  cover  quickly,  turn  the  tray  so  that  it  drops  into  the  water, 
replace  the  cover  immediately.  This  manipulation  is  to  be  made  as 
rapidly  as  possible  to  avoid  loss  of  heat.  Thus  it  remains  for  twenty- 
five  minutes. 


586  ANIMAL  FOODS:  MILK 

Now  take  the  tray  out  of  the  water  and  fasten  the  corks  or  stop- 
pers air-tight.  Cool  the  bottles  with  cold  water  and  ice  as  quickly  as 
possible,  and  keep  them  at  this  low  temperature  until  cold. 

Use  the  milk  from  the  bottles  and  by  no  means  pour  it  into  another 
vessel. 

The  milk  should  not  be  used  for  children  later  than  twenty-four  hours 
after  pasteurization. 

Emphasis  is  laid  on  the  fact  that  only  fresh,  clean  milk,  which  has 
been  kept  cold,  should  be  used. 

The  Effect  of  Heat  upon  Milk. — The  changes  produced  in  milk  by 
heating  depend  upon  the  degree  of  heat  and  the  length  of  exposure. 
Milk  heated  at  62.8°  C.  for  30  minutes  does  not  undergo  any  appreciable 
chemical  and  physical  change.  The  boiling  of  milk,  however,  pro- 
duces pronounced  changes.  In  the  main,  these  consist  of  a  partial  de- 
composition of  the  proteins  and  other  complex  nitrogenous  derivatives; 
diminution  of  the  organic  phosphorus  and  an  increase  of  inorganic  phos- 
phorus ;  precipitation  of  the  calcium  and  magnesium  salts  and  the  greater 
part  of  the  phosphates;  expulsion  of  the  greater  part  of  the  carbon 
dioxid;  caramelization  or  burning  of  a  certain  portion  of  the  milk  sugar, 
causing  the  brownish  color;  partial  disarrangement  of  the  normal  emul- 
sion, and  coalescence  of  some  of  the  fat  globules;  coagulation  of  the 
serum  albumin,  which  begins  at  75°  C. ;  the  ferments  are  killed. 

Boiled  milk  has  a  cooked  taste  which  appears  at  about  70°  C.    This 
is  due  perhaps  to  the  decomposition  of  certain  of  the  proteins  in  the 
milk.    The  loss  of  certain  gases  also  alters  the  taste,  so  that  milk  heated ' 
in  closed  vessels  has  a  less  pronounced  flavor  than  if  heated  in  open 
vessels. 

Milk  heated  in  the  open  air  forms  a  pellicle  which  renews  if  it  is 
removed.  This  scum  forms  when  milk  reaches  about  60°  C.  It  con- 
sists of : 

Fatty  matter 45 .42  per  cent. 

Casein  and  albuminoid 50 .  86  per  cent. 

Ash 3 .  72  per  cent. 

Milk  heated  in  closed  vessels  does  not  form  a  pellicle,  even  when 
the  temperature  reaches  the  boiling  point.  It  seems  that  this  pellicle 
is  due  mainly  to  the  drying  of  the  iipper  layer  of  the  liquid. 

After  milk  has  been  heated  to  68°  C.  or  over  for  half  an  hour,  the 
cream  does  not  rise  well,  if  at  all,  owing  to  the  increase  in  the  vis- 
cosity of  the  fluid  in  which  it  is  emulsified.  The  clusters  of  fat  drop- 
lets which  are  agglutinated  into  masses  in  normal  milk  are  broken  down 
by  heating,  and  the  globules  are  more  homogeneously  distributed  through- 
out the  fluid.  ■  ::  ■'TB': 

It  has  been  observed  that  cooked  milk  coagulates  with  rennin  more 


MILK  587 

slowly  than  raw  milk.  This  effect  is  noted  often  at  temperatures  of 
80°  to  90°  C,  but  has  not  been  observed  in  milk  heated  to  60°  C.  for 
20  minutes.  The  curd  produced  by  rennin  coagulation  in  cooked  milk 
is  softer,  less  tough,  and  more  flocculent  than  that  produced  by  rennin 
coagulation  in  raw  milk.  This  is  believed  to  be  an  advantage  favor- 
ing the  digestibility  of  heated  milk.  Cooked  milk  is  said  to  be  con- 
stipating. This  is  explained  by  the  fact  that  cooked  milk  contains 
comparatively  few  bacteria  and  is,  therefore,  less  irritating  than  raw 
milk. 

The  Essential  Requirements  for  a  Safe  and  Satisfactory  Milk  Sup- 
ply.— ^1.  Cows  should  be  healthy  and  free  especially  from  communica- 
ble infections,  or  any  febrile  disease,  or  inflammatory  condition  of  the 
udder. 

2.  All  persons  who  in  any  way  come  in  contact  with  the  milk  or 
milk  apparatus  should  be  free  from  communicable  diseases  and  not  be 
carriers.     A  minimum  of  human  contact  should  be  insisted  upon. 

3.  The  milking  should  be  done  in  clean  rooms,  the  udders  washed; 
the  hands  of  the  milker  should  be  clean  and  dry. 

4.  The  milk  should  be  received  into  clean,  sterilized  pails,  with  a  small 
mouth  so  as  to  keep  out  dust  and  dirt  which  falls  from  the  udder  and 
belly  of  the  cow.  If  strainers  are  used  they  should  be  cleaned  or  boiled 
morning  and  evening.  Cans  and  pails  should  be  cleaned  with  washing 
soda  or  alkaline  powder  and  then  steamed  or  boiled. 

5.  The  milk  should  be  chilled  to  50°  F.  or  under  at  once,  and  kept 
protected  from  flies,  dust,  and  contamination  in  a  clean  milk  house  until 
collected.  A  wooden  paddle  should  not  be  used  to  stir  the  milk.  If 
stirred  a  metal  paddle  is  preferable. 

6.  The  milk  should  likewise  be  kept  protected  and  cold,  not  higher 
than  50°  F.,  in  transit  to  the  city,  and  protected  against  tampering  en 
route.  The  lower  the  temperature  the  easier  it  will  be  to  keep  the 
bacterial  count  down. 

7.  All  apparatus  at  the  city  dairy,  such  as  tanks,  clarifiers,  separators, 
pasteurizers,  and  bottling  machines,  should  be  kept  scrupulously  clean 
and  sterilized  by  steam. 

8.  Pasteurization  at  not  less  than  60°  for  20  minutes,  followed  by 
rapid  chilling,  and  the  milk  kept  below  50°  F.  until  delivered  to  the 
consumer. 

9.  The  pasteurized  milk  to  be  bottled  by  machinery  in  sterilized  bot- 
tles, well  sealed;  and  delivered  promptly  to  the  consumer. 

10.  All  bottles  and  cans,  after  use  in  city  delivery,  should  be  washed 
and  sterilized  before  being  returned  to  the  producer  in  order  to  prevent 
the  conveyance  of  infection  to  the  dairy  or  country  farm. 

11.  The  milk  must  be  graded.  In  this  way  the  producer  is  paid 
for  care  and  cleanliness  and  the  consumer  has  a  ready  means  of  knowing 


588  ANIMAL  FOODS:  MILK 

the  sanitary  character  of  the  milk  he  purchases.     The  health  officer 
should  make  frequent  bacterial  counts  for  the  purpose  of  grading. 
12.  A  system  of  inspection  to  insure  the  above  requirements. 


THE  BACTERIOLOGICAL  EXAMINATION  OF  MILK 

The  Number  of  Sacteria. — No  known  method  can  give  an  enumera- 
tion of  all  the  bacteria  in  milk.  Some  are  aerobes,  others  anaerobes; 
some  require  alkaline,  others  acid  media;  some  grow  best  at  room  tem- 
perature, others  only  at  blood  temperature;  and  some  grow  slowly  or 
not  at  all  upon  ordinary  media.  The  methods  in  use,  therefore,  are 
those  which  have  been  shown  by  experiments  to  give  the  highest  counts 
and  the  maximum  information  under  ordinary  conditions. 

For  the  sake  of  uniformity  methods  should  follow  the  report  of 
the  Committee  on  Standard  Methods  of  Bacterial  Milk  Analysis  of  the 
American  Public  Health  Association.^ 

The  samples  must  be  collected  and  kept  in  such  a  manner  as  to 
prevent  either  any  addition  of  bacteria  from  without  or  multiplication 
of  the  bacteria  originally  present.  Whenever  possible,  and  especially 
in  the  selection  of  certified  milk  samples,  an  original  package  should  be 
taken,  placed  in  a  suitably  iced  case,  and  brought  at  once  to  the  labora- 
tory. Samples  of  market  milk  may  be  collected  in  the  same  manner  as 
water  samples,  in  sterile,  wide-mouthed,  glass-stoppered  four-ounce  bot- 
tles. Care  should  be  taken  to  secure  a  sample  which  is  thoroughly  repre- 
sentative of  the  milk  to  be  examined.  This  may  be  done  by  pouring  the 
milk  back  and  forth  into  a  sterile  receptacle,  or  shaking  the  milk  thor- 
oughly with  the  receptacle  turned  upside  down.  In  taking  samples  from 
tanks  it  is  allowable  to  stir  thoroiighly  with  a  long-handled  dipper.  Gen- 
erally speaking,  the  shorter  the  time  between  collection  and  examination  of 
milk  samples  the  more  ac^curate  will  be  the  results.  For  routine  work  the 
attempt  should  be  made  to  plate  within  four  hours  of  the  time  of  collec- 
tion. Too  much  stress  cannot  be  laid  on  the  importance  of  keeping  the 
samples  properly  iced  during  this  interval.  They  should  be  kept  below 
40°  F.,  but  care  should  be  taken  that  they  are  not  frozen. 

The  standard  medium  for  routine  enumeration  of  bacteria  in  milk 
is:  agar,  1  per  cent.,  reaction  +1.5,  Fuller's  scale.^  Milk  should  al- 
ways be  diluted  before  plating,  for  the  reason  that  whole  milk  produces 
a  turbidity  of  the  agar,  and  because  the  bacteria  cannot  well  be  dis- 
persed without  diluting,  and  the  resulting  colonies  are  so  close  that  they 
interfere  with  each  other.    The  milk  is  diluted  in  the  proportion  of  1-10, 

^American  Journal  of  Public  Hygiene,  August,  1910,  VI,  3,  p.  315.  Modi- 
fied December,  1915,  Vol.  V,  No.  12,  p.  1261. 

^'^sculin  bile  salt,  agar,  lactose,  litmus  agar,  and  whey  agar  may  also 
be  used. 


THE  BACTERIOLOGICAL  EXAMINATION  OF  MILK     589 

1-100,  1-1,000,  1-10,000,  1-100,000,  or  1-1,000,000.  For  certified  milk 
1-100  dilution  should  be  used.  Ordinary  potable  water,  sterilized,  may 
be  used  for  dilutions.  The  number  of  bacteria  present  may  be  estimated 
approximately  before  dilutions  are  made  by  direct  microscopic  examina- 
tion of  a  properly  prepared  sediment.  Otherwise  it  is  necessary  to  make 
a  range  of  dilutions  therefrom,  selecting  for  record  the  count  obtained 
on  that  plate  which  yields  between  30  and  200  colonies.  A  plate  con- 
taining more  or  less  than  these  numbers  will  not  give  reliable  results. 
Porous,  earthenware  Petri  dish  covers  are  recommended  as  superior  to 
glass,  since  they  absorb  the  excess  of  moisture  and  thus  help  prevent 
spreaders.  Another  method  of  preventing  spreaders  is  to  invert  the 
dishes  and  place  in  the  glass  cover  of  each  a  strip  of  sterile  filter  paper 
moistened  with  one  large  drop  of  glycerin. 

The  plating  should  always  be  checked  by  duplicate  controls,  and 
a  blank  plate  should  be  made  with  each  series  for  control  of  the  steril- 
ity of  the  agar,  water,  air,  Petri  dishes,  pipettes,  and  methods.  The 
plates  should  be  incubated  at  37°  C.  for  48  hours,  or  may  be  grown  at 
21°  C.  for  five  days.  Only  those  colonies  should  be  counted  which  are 
visible  to  the  naked  eye  or  may  be  seen  readily  by  a  low  power  lens.^ 
The  result  should  always  be  expressed  in  round  numbers.  It  is  mis- 
leading to  state  that  a  milk  contains  2,140,672  bacteria  per  cubic 
centimeter.  This  gives  a  false  and  exaggerated  notion  of  the  accuracy 
of  the  method.  At  best  the  results  are  only  an  average  approx- 
imation. Results  should  be  expressed  in  accordance  with  the  recom- 
mendations of  the  Commission  on  Standards  of  the  New  York  Milk 
Committee.^ 

The  number  of  bacteria  is  the  best  single  index  we  have  of  the 
general  character  of  milk. 

The  Kinds  of  Bacteria. — We  still  lack  satisfactory  routine  methods 
for  determining  the  kinds  of  bacteria  found  in  milk.  If  the  plates  are 
made  with  gelatin  it  will  give  the  relative  proportion  of  liquefiers.  By 
the  use  of  Endo's  medium  or  lactose  litmus  agar  the  number  of  acid- 
producing  bacteria  may  be  determined.  The  number  of  fermenting  or- 
ganisms may  be  estimated  by  planting  progressively  smaller  quantities  in 
fermentation  tubes  containing  glucose  or  other  sugar;  or  by  the  use  of 
the  Wisconsin  curd  test.  The  presence  of  gas-producing  organisms  in 
abundance  usually  indicates  dirty  conditions  of  stables,  cows,  or  con- 
tainers. 

To  determine  the  number  of  proteolytic  bacteria  in  milk  place  1  c.  c. 
of  sterile  skim  milk  into  a  Petri  dish,  then  add  the  proper  dilution  of 
milk  in  question,  and  finally  pour  in  molten  sugar-free  agar.  Incubate 
48  hours,  and  then  wash  the  surface  with  a  dilute  solution  of  acetic  acid. 

'  Magnifying  2^/^  diameters. 

^Public  Health  Reports,  Vol.   XXVII,   19,  May  10,   1912. 


590  ANIMAL  FOODS:  MILK 

Count  the  number  of  colonies  surrounded  by  a  clear  zone,  which  is  taken 
to  represent  proteolysis  or  breaking  down  of  the  protein.^ 

Typhoid  bacilli  may  be  isolated  on  Endo's  medium,  and  diphtheria 
upon  Loeffler's  blood  serum.  Other  pathogens  require  special  technic 
applicable  to  each  case.  The  number  of  streptococci  in  milk  may  be 
estimated  by  the  direct  examination  of  stained  smears.  The  chains  are 
more  readily  counted  if  the  milk  is  first  incubated  at  37°  C.  for  6  or  8 
hours.  In  the  estimation  of  streptococci  only  the  longer  chains  are  con- 
sidered. The  presence  of  streptococci  and  an  approximation  as  to  their 
number  may  also  be  determined  by  planting  the  milk  upon  the  surface 
of  blood  agar  and  studying  the  fine  dewdrop-like  colonies. 

A  few  streptococci  will  be  found  in  most  sediments  from  milk.  They 
are  seldom  found  to  any  great  extent  by  direct  microscopic  examination 
of  clean  milk.  Occasionally  a  sample  will  be  found  crowded  with  long 
chains.  More  often  streptococci,  if  present,  are  in  the  form  of  diplococei 
or  very  short  chains.  The  common  interpretation  is  to  regard  the  short 
chain  varieties  as  probably  harmless,  while  long  chains  are  regarded  as 
more  apt  to  indicate  inflammatory  reactions.  This  is  a  serious  mis- 
take.   There  is  no  relation  between  length  of  chains  and  pathogenicity. 

Euediger  points  out  that  Streptococcus  lacticus  can  be  ditferentiated 
from  Streptococcus  pyogenes  by  means  of  blood  agar  plates.  Strepto- 
coccus pyogenes  produces  small  colonies  surrounded  by  a  large  zone  of 
hemolysis,  whereas  Streptococcus  lacticus  produces  green  or  grayish  colo- 
nies with  very  little  or  no  hemolysis. 

Streptococcus  lacticus  has  no  sanitary  significance,  as  it  is  found  in 
nearly  all  samples  of  clean,  soured,  or  fresh  milk,  and  very  often  in 
the  healthy  milk  ducts.  Streptococcus  pyogenes,  on  the  other  hand, 
seems  to  occur  but  rarely  in  milk,  and  is  indicative  of  the  existence  of 
an  inflamed  condition  of  the  udder  of  the  cow  furnishing  the  milk. 

The  Beta  type  of  streptococcus  described  by  Smith  and  Brown  may 
be  isolated  from  milk  by  the  method  described  on  page  576. 

The  presence  of  Bacillus  Welcliii,  or  the  gas  bacillus,  may  be  de- 
termined by  heating  some  of  the  milk  to  80°  C.  for  one  hour  and  then 
incubating  the  sample  at  37°  C.  If  the  sample  contains  this  micro- 
organism it  will  show  "stormy  fermentation"  with  gas  production  within 
24  hours  (sometimes  as  soon  as  6  hours),  with  coagulation  and  breaking 
up  of  the  curd,  some  of  which  may  be  forced  above  the  cream  line;  and 
with  the  development  of  an  odor  of  butyric  acid. 

The  demonstration  of  tubercle  bacilli  in  milk  depends  upon  animal 
experimentation.  Guinea-pigs  are  injected  subcutaneously  with  5  c.  c.  of 
sediment  obtained  by  centrifuging,  or  with  cream,  or  both.  The  guinea- 
pigs  that  do  not  die  in  two  months  are  tested  with  sufficient  tuberculin 
(0.  T.)    to  cause  the  death  of  the  tuberculous  animals  in  24  hours. 

*  Hastings:   Cent.  f.  Baht.  u.  Parasitenk.,  Abt.  II,  Bd.  X,  p.  384. 


MICEOSCOPIC  EXAMINATION  591 

Two  c.  c.  of  the  crude  tuberculin  is  injected  subcutaneously  for  this 
purpose. 

MICROSCOPIC  EXAMINATION 

There  are  three  methods  of  making  a  microscopic  examination  of 
milk  in  current  use. 

(1)  The  Stewart-Slack  Method. — Two  c.  c.  of  milk  are  placed  in 
a  glass  tube  closed  at  both  ends  with  a  rubber  stopper.  This  is  cen- 
trifuged  for  10  minutes  at  a  speed  of  from  2,000  to  3,000  revolutions 
per  minute.  The  sediment  upon  the  rubber  stopper  of  the  distal  end 
of  the  tube  is  mixed  with  a  drop  or  two  of  water  and  spread  upon  a 
slide  in  a  thin  even  layer,  covering  a  space  of  about  four  square  centi- 
meters. This  is  dried  and  stained  with  methylene  blue.  The  micro- 
scopic examination  reveals  the  character  of  the  milk  as  judged  from 
the  approximate  number  of  pus  cells  and  presence  of  streptococci  in 
long  chains.  It  has  been  found  that  the  number  of  cocci,  bacilli,  or 
chains  in  the  1/12  oil  immersion  field,  multiplied  by  10,000,  gives  a 
rough  approximation  of  the  number  of  bacteria  in  a  cubic  centimeter 
of  the  whole  milk. 

The  results  of  this  method  vary  considerably  with  details  of  individual 
manipulation,  with  the  speed  of  the  centrifugal  machine,  with  the  time 
allowed  for  centrifugation,  and  other  factors. 

(2)  The  Doane-Buckley  Method. — In  this  method  the  number  of 
leukocytes  are  counted  in  the  chamber  of  the  Zeiss  blood  counter,  which 
contains  just  0.0001  c.  c.  Ten  c.  c.  of  milk  is  centrifuged  at  2,000  revo- 
lutions per  minute  for  four  minutes.  The  fat  is  removed  with  a  cotton 
swab  and  again  centrifuged  for  one  minute.  The  fat  is  again  carefully 
removed,  for  any  appreciable  amount  of  fat  will  interfere  with  the  count- 
ing. The  supernatant  fluid  is  now  pipetted  off  and  two  drops  of  a  satu- 
rated alcoholic  solution  of  methylene  blue  are  added  to  the  sediment, 
which  is  thoroughly  mixed  and  warmed  in  boiling  water  for  two  or 
three  minutes,  which  favors  the  staining  of  the  cells.     The  sediment  is 

'  now  diluted  to  the  1  c.  c.  mark  with  water.  Some  of  this  is  transferred  to 
the  counting  chamber  and  the  number  of  cells  counted  with  a  dry  lens. 
The  number  of  cells  in  the  counting  chamber  multiplied  by  1,000  gives 
the  number  per  c.  c.  in  the  milk. 

(3)  The  Prescott-Breed  Method. — A  capillary  tube  is  prepared,  ar- 
ranged to  receive  a  rubber  bulb  at  one  end,  and  marked  carefully  to 
deliver  0.01  c.  c.  After  a  most  thorough  mixing  of  the  milk,  0.01  c.  c. 
is  removed  with  the  sterilized  pipette  and  spread  uniformly  over  a  square 
centimeter  on  an  ordinary  microscopic  slide.  It  is  allowed  to  dry  and 
is  fixed  with  methyl  alcohol,  after  which  the  fat  is  dissolved  from  it 
by  the  use  of  xylol.     The  smear  is  then  stained  either  with  methylene 


593  ANIMAL  FOODS:  MILK 

blue  or  preferably  with  one  of  the  blood  stains,  the  Jenner  stain  or 
Wright  stain  being  useful  for  this  purpose.  If  the  staining  is  so  deep 
as  to  make  the  specimen  too  opaque  for  proper  study,  it  is  slightly  de- 
colorized with  alcohol,  which  removes  the  stain  from  the  general  sedi- 
ment more  readily  than  it  does  from  the  bacteria  of  the  tissue  cells. 
The  stained  smear  is  studied  under  a  1/12  inch  immersion  lens.  The 
draw  tube  is  adjusted  so  that  the  field  of  the  microscope  covers  exactly 
15  millimeters,  and  under  these  circumstances  the  number  of  bacteria 
present  in  the  0.01  c.  c.  is  exactly  5,000  times  the  number  found  in  a 
microscopic  field.  The  counting  of  a  large  number  of  fields  (100 
fields)  and  averaging  the  results  multiplied  by  this  number  will,  there- 
fore, give  approximately  the  number  of  cells  or  bacteria  contained  in 
0.01  c.  c.  of  milk. 


CHEMICAL  ANALYSIS  OF  MILK 

Total  Solids. — The  total  solids  in  milk  consist  chiefly  of  the  fats, 
sugar,  proteins,  and  inorganic  salts.  The  United  States  standard  re- 
quires 12  per  cent,  of  the  milk  to  consist  of  total  solids,  8.5  per  cent, 
of  which  shall  be  solids,  not  fat,  and  3.25  per  cent.  fat.  In  some  states 
the  requirement  for  total  solids  is  as  high  as  13  per  cent.,  in  others 
11.5  per  cent. 

Determination  of  Total  Solids. — The  total  solids  may  be  determined 
either  by: 

(1)  The  use  of  Richmond's  slide  rule. 

(2)  The  Babeock  asbestos  method. 

(3)  By  evaporation  and  direct  weighing. 

Eichmond's  Slide  Eule. — This  is  a  device  by  which  the  total  solids 
may  be  determined  fairly  accurately  by  the  use  of  the  formula  of  Hehner 
and  Eichmond.  It  is  necessary  to  know  the  correct  specific  gravity  and 
the  amount  of  fat.  From  this  the  total  solids  is  determined  by  the  fol- 
lowing formula : 

G 

T  S=(— )+1.3  F+.14 
4 

in  which  T  S  equals  total  solids,  G  the  last  two  units  of  the  specific 
gravity  and  any  decimal.  Thus,  if  the  specific  gravity  is  1.0295,  G= 
29.5.  F  represents  the  percentage  of  fat.  In  using  the  slide  rule  the 
operation  is  conducted  in  two  stages.  First,  the  lactometer  reading  is 
corrected  for  temperature.  The  observed  lactometer  reading  is  brought 
opposite  the  60°  mark  and  the  correct  specific  gravity  read  opposite  the 
observed  temperature.     Second,  the  arrow  of  the  slide  is  set  opposite 


CHEMICAL  ANALYSIS  OF  MILK  593 

the  observed  percentage  of  fat,  and  the  total  solids  are  read  off  opposite 
the  corrected  specific  gravity  reading  on  the  scale  marked  "specific 
gravity."  The  results  obtained  by  the  use  of  Eichmond's  slide  rule 
agree  quite  closely  with  those  obtained  by  direct  weighing. 

This  formula  may  also  be  used  to  determine  the  percentage  of  fat 
provided  the  specific  gravity  and  total  solids  are  known. 

The  Babcock  Asbestos  Method. — The  milk  is  placed  upon  a  filter 
paper  cartridge  filled  loosely  with  freshly  ignited  woolly  asbestos;  sub- 
jected to  a  temperature  of  100°  C.  until  weight  is  constant,  and  then 
cooled  and  weighed.  The  gain  in  weight  represents  the  total  solids  of 
the  amount  of  milk  taken.  The  advantage  in  this  method  is  that  the 
cartridge  may  then  be  slipped  into  the  Soxhlet  extraction  apparatus  and 
used  for  the  determination  of  fat. 

Weighing. — About  5  c.  c.  of  milk  are  weighed  in  a  tared  platinum 
dish,  evaporated  exactly  two  hours  on  a  steam  bath,  the  outside  wiped 
dry,  and  then  cooled  to  constant  weight  in  a  desiccator.  The  weight  of 
the  residue  represents  the  total  solids  of  the  milk. 

Determination  of  Ash. — The  platinum  dish  containing  the  total 
solid  residue  is  carefully  heated  in  the  flame,  avoiding  spattering  and 
heating  above  a  dull  red  glow.  When  the  residue  has  become  white,  or 
nearly  so,  it  is  cooled  in  a  desiccator  and  again  weighed;  the  difference 
between  the  final  weight  and  the  original  weight  of  the  empty  dish 
represents  the  amount  of  mineral  matter  in  the  amount  of  milk  taken. 
The  ash  is  saved  for  the  tests  for  boron  compounds,  carbonates,  and 
other  non-volatile  mineral  preservatives. 

Determination  of  Fats. — The  determination  of  the  quantity  of  butter 
fat  contained  in  milk  is  of  considerable  economic  importance  and  is 
included  as  a  routine  in  all  milk  laboratories.  There  are  several  methods 
by  which  the  fat  in  milk  may  be  accurately  determined. 

(1)  Babcock  Method. — The  Babcock  method  is  the  most  conveni- 
ent and  is  sufficiently  accurate  for  ordinary  purposes.  It  cannot  be 
carried  out  without  considerable  special  apparatus,  including  a  centrifuge, 
special  graduated  flasks  and  pipettes.  The  principle  of  this  method  de- 
pends upon  separating  the  fat  by  means  of  the  addition  of  sulphuric 
acid.  The  mixture  is  centrifugalized  so  that  the  fat  rises  into  the  neck 
of  the  specially  graduated  flask,  and  the  percentage  may  be  read  off 
directly.  The  sample  should  be  well  mixed  by  pouring  back  and  forth 
just  before  the  test.    The  method  is  carried  out  as  follows : 

In  the  special  graduated  flask  are  mixed: 

17.6  c.  c.  milk. 

17.5  c.  c.  of  sulphuric  acid  (specific  gravity  1.82-1.83). 

The  acid  must  be  run  slowly  down  the  side  of  the  flask  under  the 
milk  and  the  whole  mixed  at  once,  without  splashing,  by  imparting  a 


594  ANIMAL  FOODS:  MILK 

rotary  motion  to  the  contents  of  the  bottle.  The  mixture  is  centrifugal- 
ized  for  5  minutes;  boiling  M^ater  is  then  added  until  the  liquid  rises  to  the 
bottom  of  the  neck  of  the  flask,  and  the  centrifugalization  is  repeated  for 
3  minutes.  Again  add  boiling  water  until  the  top  of  the  column  is  near 
but  safely  under  the  top  of  the  scale,  and  centrifugalize  a  third  time  for 
1  minute.  By  this  time  the  fat  in  the  neck  of  the  bottle  should  be  clear, 
yellow,  and  liquid.  The  length  of  the  column  of  fat  is  considered  as 
extending  from  the  bottom  of  the  line  of  contact  with  the  liquid  below 
to  the  top  of  the  meniscus  above.  The  length  of  the  column  of  fat 
is  measured  by  means  of  a  pair  of  dividers,  which  are  first  adjusted  to  the 
length  of  the  column  of  fat,  and  the  percentage  read  by  touching  one 
point  of  the  dividers  to  the  zero  mark  on  the  scale,  when  the  upper  point 
will  indicate  the  percentage  of  fat  in  the  milk.  The  mixing  of  sulphuric 
acid  with  the  milk  generates  considerable  heat,  which  should  be  main- 
tained, so  that  at  the  time  of  taking  the  reading  the  contents  of  the 
bottle  register  between  55°-60°  C.  Care  should  be  taken  to  use  none 
but  authoritatively  tested  and  guaranteed  bottles.  The  flasks  should  be 
emptied  before  the  fat  cools  and  hardens. 

(2)  The  Werner- Schmidt  Method. — This  method  is  slower  than 
the  Babcock,  especially  when  many  samples  are  to  be  analyzed,  but  it 
can  be  done  with  improvised  apparatus  and  readily  procurable  materials. 
Ten  c.  c.  of  milk  are  added  to  10  c.  c.  of  concentrated  hydrochloric  acid 
in  a  50-c.  c.  test  tube,  shaken,  and  boiled  until  dark  brown  in  color.  The 
mixture  is  then  cooled  in  water  and  30  c.  c.  of  washed  ether  added,  the 
stopper  inserted,  and  thoroughly  agitated.  When  the  two  layers  have 
separated  the  upper  layer  containing  the  ether  and  dissolved  fat  may  be 
withdrawn  by  means  of  a  pipette,  or  blown  out  with  the  assistance  of  a 
double  tube,  such  as  is  used  in  wash-bottles,  the  delivery  tube  extending 
into  the  ether  layer  almost  to  the  line  of  demarcation  between  the  ether 
and  the  acid-milk  mixture.  The  ether  containing  the  extracted  fat  is 
transferred  to  a  weighed  flask.  The  extraction  is  repeated  with  several 
fresh,  smaller  portions  of  ether  (about  10  c.  c),  and  the  whole  of  the 
ether  used  is  collected  in  the  weighed  flask.  The  ether  is  then  distilled  off 
or  permitted  to  evaporate  at  a  low  temperature.  The  residuum  of  fat  is 
heated  to  constant  weight  in  an  air  bath,  cooled,  and  weighed.  Since  the 
milk  is  measured  and  not  weighed,  a  correction  must  be  made  accordingly. 

Example. — Amount  of  milk  used  equals  10  c.  c.  Specific  gravity  of 
sample  equals  1.029.  Weight  of  milk  used,  therefore,  equals  1.029X10? 
which  equals  10.29  grams.  The  weight  of  the  fat  found  equals  0.386 
gram.  Percentage  of  the  fat  in  the  original  milk  is  determined  from 
the  following  equation : 

10.29  :0.386::100:x 

x^3.97;  or  the  percentage  of  fat  in  the  original  milk. 


CHEMICAL  ANALYSIS  OF  MILK  595 

(3)  The  Soxhlet  Extraction  Method. — This  is  the  most  accu- 
rate method  for  determining  fats  in  milk  and  other  substances.  The 
principle  depends  upon  the  complete  extraction  of  all  the  fat  by  con- 
tinuous washing  with  ether.  The  only  error  in  this  method  consists  in 
the  fact  that  substances  other  than  fats  are  soluble  in  ether  and  are  in- 
cluded in  the  weight.  This  error  in  milk  is  negligible.  The  process 
requires  a  coil  of  thick  filter  paper  free  from  substances  soluble  in  ether 
and  alcohol,  and  a  Soxhlet  extraction  apparatus.  Instead  of  the  coil 
of  filter  paper  a  specially  prepared  cartridge  of  filter  paper,  which  fits 
loosely  within  the  cylinder  of  the  Soxhlet  apparatus,  may  be  used.  When 
the  cartridge  is  used  it  is  best  to  plug  its  open  end  with  absorbent  cotton, 
in  order  to  prevent  the  escape  of  fine  particles  of  the  contained  substance, 

A  definite  weight  of  milk,  about  5  grams,  is  applied  to  the  coil  of 
filter  paper  or  cartridge,  in  one  of  two  ways.  A  small  beaker  containing 
the  required  amount  is  weighed  and  the  coil  is  placed  into  it  and  kept 
there  until  nearly  the  whole  has  been  absorbed.  The  coil  is  then  care- 
fully withdrawn  and  placed,  dry  edge  downward,  upon  a  sheet  of  glass. 
The  beaker  is  then  weighed  again,  and  the  loss  in  weight,  which  repre- 
sents the  amount  of  milk  absorbed,  is  noted.  Another  method  is  to 
weigh  the  beaker  containing  the  milk  and  a  small  pipette.  The  neces- 
sary amount  of  milk  is  then  transferred  to  the  coil  with  the  pipette, 
after  which  the  weight  of  the  beaker  and  pipette  containing  the  re- 
maining milk  is  noted.  The  difference  represents  the  weight  of  the 
milk  absorbed.  The  coil  or  cartridge  is  then  dried  in  an  air  bath  at 
100°  C.  for  an  hour  or  more,  when  it  is  ready  for  insertion  into  the 
extractor. 

The  three  separate  parts  of  the  Soxhlet  extraction  apparatus,  con- 
sisting of  the  flask,  the  cylinder,  and  the  condenser,  are  joined  together 
and  mounted  upon  a  water  bath  or  an  electrically  heated  plate.  Before 
the  operation  is  begun  the  exact  weight  of  the  flask  must  be  determined. 
The  ether  is  then  added,  and  as  it  volatilizes  the  vapor  passes  upward 
through  the  side  tube  into  the  extractor,  and  thence  to  the  condenser, 
where  it  falls  upon  the  substance  to  be  extracted.  As  the  process  con- 
tinues the  condensed  liquid  accumulates  in  the  cylinder  and  gradually 
rises  until  it  reaches  the  bend  of  the  siphon  in  the  cylinder  part  of  the 
apparatus.  When  full  the  siphon  acts  and  discharges  back  into  the 
flask,  until  the  entire  liquid  is  returned  to  its  starting  point.  During 
its  accumulation  in  the  cylinder  it  dissolves  the  fats  or  other  ether 
soluble  substances  which  are  carried  in  solution  into  the  flask.  The 
process  is  continued  until  this  siphoning  action  repeats  itself  again  and 
again  as  long  as  is  necessary,  so  that  the  whole  of  the  extracted  matter 
is  finally  within  the  flask.  The  fat,  being  non-volatile,  remains  in  the 
flask  while  the  ether  is  revolatilized  and  sent  continually  on  its  errand. 
On  the  completion  of  the  process  the  ether  is  permitted  to  collect  in  the 


596  ANIMAL  FOODS:  MILK 

cylinder,  but  before  it  reaches  the  level  of  the  siphon  the  flask  is  dis" 
joined.  The  remaining  ether  is  expelled  cautiously  and  the  flask  with  its 
contents  is  placed  in  an  air  bath  maintained  at  100°  C.  and  dried  to 
constant  weight.  The  increase  in  the  weight  of  the  flask  represents  the 
amount  of  matter  extracted. 

Example. — The  weight  of  milk  absorbed  by  the  filter  paper  was 
5.160  grams.  The  increase  in  the  weight  of  the  flask  was  0.161  gram. 
The  amount  of  fat  nresent  in  the  sample  is  then  obtained  by  the  fol- 
lowing equation: 

5.16:0.161::100:x 

x=r3.20,  or  the  percentage  of  fat  in  the  milk. 

Determination  of  Milk  Sugar. — The  amount  of  lactose  in  milk  may 
be  determined  chemically  by  the  reduction  of  copper  sulphate  in  Fehling 
solution,  or  optically  by  means  of  the  polariscope. 

(1)  Method  by  Fehling's  Solution. — To  25  grams  of  milk  add 
0.5  c.  c.  of  30  per  cent,  acetic  acid;  shake;  let  stand  3  minutes;  then 
add  100  c.  c.  of  boiling  water;  again  shake;  add  25  c.  c.  of  alumina 
cream;  again  shake,  and  let  stand  for  10  minutes;  filter  through  a  wet 
pleated  paper  filter  and  wash  the  residue  until  the  washings  and  filtrate 
total  250  c.  c,  representing  a  dilution  of  1-10  of  the  original  milk; 
this  dilutes  the  sugar  content  of  the  liquid  to  somewhat  less  than  0.5 
per  cent.  This  is  then  titrated  with  Fehling's  solution  in  the  usual 
manner,  namely:  fill  a  burette  with  sugar-containing  liquid,  place  10 
c.  c.  of  Fehling's  solution  (representing  0.067  gram  of  milk  sugar)  in 
a  flask,  and  heat  to  boiling.  Eun  in  the  liquid  from  the  burette  in  small 
portions,  maintaining  the  contents  of  the  flask  at  boiling  point  until  the 
liquid  in  the  flask  loses  its  original  blue  color,  which  marks  the  end 
point  of  the  reaction. 

Fehling's  solution  is  made  up  in  two  solutions:  1.  Dissolve  34.639 
grams  of  pure  sulphate  of  copper  in  distilled  water  and  dilute  it  to  a 
liter.  2.  Dissolve  173  grams  of  potassium  sodium  tartrate  (Eochelle 
salt)  in  distilled  water,  add  100  c.  c.  of  sodium  hydrate  solution  of 
1.393  specific  gravity,  and  dilute  the  mixture  with  distilled  water  to 
a  liter.  Equal  parts  of  solution  1  and  2  are  mixed  in  a  boiling-flask 
of  about  300  c.  c.  capacity.  The  amount  of  copper  contained  in  10  c.  c. 
of  equal  parts  of  solution  1  and  2  requires  for  its  reduction  0.050  gram 
of  dextrose,  or  0.067  gram  of  lactose. 

Polariscope  Method. — The  polariscope,  the  quantities  used,  and  the 
factors  employed  in  the  polariscope  method  vary  with  different  types  of 
instruments.  Perhaps  the  most  satisfactory  is  the  Schmidt  and  Haenzsch 
half-shadow  type.  This  possesses  the  advantage  of  doing  away  with  the 
matching  of  colors,  and  hence  may  be  used  by  those  who  are  color-blind, 
at  a  temperature  of  20°  C.     Distilled  water  gives  with  the  same  in- 


CHEMICAL  ANALYSIS  OF  MILK  597 

and  even  with  those  having  normal  color  vision  it  gives  the  most  satisfac- 
tory results. 

To  70.65  grams  of  milk  add  an  excess  (3  c.  c.)  of  an  acid  nitrate  of 
mercury  solution  and  mix  thoroughly  by  shaking.  The  acid  nitrate  of 
mercury  solution  is  made  by  adding  one  part  of  weight  of  mercury  to  two 
parts  of  nitric  acid,  S.  G.  1.42,  and,  after  the  reaction  has  ceased,  adding 
an  equal  volume  of  distilled  water.  The  object  of  adding  the  acid  nitrate 
of  mercury  to  the  milk  is  to  remove  the  albumin  and  fat  in  the  form 
of  a  curd,  leaving  the  sugar  as  the  only  optically  active  constituent  of 
the  clear  serum.  The  milk  containing  the  acid  is  now  diluted  to  102.5 
c.  c.  with  distilled  water  and  again  thoroughly  mixed.  Filter  through  a 
dry  pleated  filter  and  take  the  polarimeter  reading  without  delay  in  a 
200-mm.  tube.  When  an  excess  of  acid  nitrate  of  mercury  is  added  to 
the  sugar-containing  liquid  the  latter  quickly  begins  to  decompose,  with 
the  evolution  of  gas;  on  the  other  hand,  an  excess  must  be  present  in 
order  to  obtain  a  clear,  easily  filtered  liquid. 

The  percentage  of  lactose  is  the  product  of  the  factor  0.0209  (this 
factor  is  applicable  to  these  conditions  only)  multiplied  by  the  number 
of  minutes  of  dextrorotation.  The  definite  directions  for  this  particu- 
lar kind  of  work  do  not  accompany  the  instrument  used.  The  factor 
should  be  determined  or  confirmed  by  comparing  with  lactose  solution 
of  known  strength.  Some  polarimeters  are  graduated  directly  in  sugar 
percentages  instead  of  degrees  and  minutes,  in  which  case  care  must 
be  taken  that  the  graduations  correspond  to  the  particular  form  of  sugar 
under  investigation,  or,  if  not,  that  a  suitable  correction  is  made. 

Determination  of  Proteins. — It  is  not  usual  to  estimate  the  proteins 
in  a  sanitary  analysis  of  milk,  since  difi^erent  specimens  of  milk  vary 
very  little  in  this  regard,  and  since  there  is  little  inducement  for  sophisti- 
cation, as  far  as  the  proteins  are  concerned. 

(1)  Method  by  Difference. — If  we  know  the  weight  of  total  solids 
in  milk  and  subtract  therefrom  the  weight  of  the  fat,  ash,  and  sugar, 
the  difference  will  represent  the  proteins.  This  method  is  sufficient  for 
ordinary  purposes.  To  estimate  the  nature  of  the  various  proteins  re- 
quires special  skill  in  organic  analysis. 

(2)  Kjeldahl  Method. — The  milk  is  mixed  with  sulphuric  acid 
(using  mercury  as  a  catalyzer)  and  digested  in  a  flask  until  it  is  com- 
pletely charred  and  becomes  clear  again.  The  residue  will  then  contain 
all  of  the  nitrogen  in  the  form  of  ammonium  sulphate,  which  is  deter- 
mined in  the  usual  way.  The  total  nitrogen  multiplied  by  the  factor  6.38 
gives  the  total  protein.    The  method  is  carried  out  as  follows : 

Gunning  Modification. — An  accurately  weighed  amount  (about  5 
grams)  of  milk  is  placed  in  a  500-c.  c.  Kjeldahl  digestion  flask  and 
digested  with  10  grams  of  potassium  sulphate  and  15  c.  c.  of  concen- 
trated nitrogen-free  sulphuric  acid.     The  iigestion  is  carried  out  over 


598  ANIMAL  FOODS:  MILK 

a  free  flame,  using  care  to  heat  gradually  at  first;  the  process  is  con- 
sidered complete  when  the  liquid  becomes  clear  (about  2  hours).  The 
contents  of  the  flask  are  cooled  and  200  c.  c.  of  water  and  sufficient 
saturated  sodium  hydroxid  solution  to  neutralize  the  acid  and  to  make 
the  solution  strongly  alkaline  are  added.  The  nitrogen,  which  has  been 
converted  into  ammonium  sulphate,  is  now  distilled  through  a  block 
tin  tube  into  a  definite  amount  of  standard  acid,  and  the  acid  titrated 
back  with  standard  alkali,  using  cochineal  or  alizarin  as  indicator.  The 
amount  of  nitrogen  can  be  calculated  from  the  results.  Total  nitrogen 
multiplied  by  6.38  gives  total  protein. 

Calculation. — The  number  of  c.  c.  of  N/10  acid  multiplied  by  .0014, 
divided  by  the  weight  of  the  sample  of  milk  times  100  gives  the  per- 
centage of  nitrogen.  1  c.  c.  of  N/10  acid  equals  .0014  gram  of  N.  As 
the  reagents  always  contain  a  certain  amount  of  nitrogen  the  value  of  a 
blank  determination  should  always  be  subtracted  from  the  acid  reading. 

The  percentage  of  nitrogen  multiplied  by  the  factor  6.38  gives  the 
percentage  of  protein  in  the  sample  of  milk. 
Example : 

50 . 5 — No.  c.  c.  of  N/10  acid  originally  in  receiving  flask. 
18 . 8 — No.  c.  c.  of  N/10  alkali  used  in  titration. 


31.7 

.  3 — ^Value  from  blank  determination. 


31.4— Total  No.  c.  e.  N/10  acid  used. 
.0014 

.044 — Wt.  of  nitrogen. 
.044 

X 100=. 427.    Percentage  of  nitrogen. 

10.3 

.427X6.38=2.72.  Percentage  of  protein. 

Note. — The  factor  10.3  in  the  above  formula  is  the  weight  of  the 
sample  of  milk  used,  i.  e.,  the  volume  (10  c.  c.)  times  the  specific  gravity 
of  the  milk. 

Water. — Milk  is  still  frequently  sophisticated  by  the  addition  of 
water.  A  watered  milk  may  be  suspected  from  a  low  specific  gravity, 
or  may  be  detected  unerringly  by  the  index  of  refraction  of  the  milk 
serum. 

Eefeactometer  Reading. — This  test  depends  upon  the  fact  that 
the,  salts  dissolved  in  undiluted  milk  in  the  concentration  in  which  they 
exist  in  the  milk  serum,  as  prepared  under  standard  conditions,  give 
a  reading  of  not  less  than  39  upon  the  scale  of  a  Zeiss  refractometer 


CHEMICAL  ANALYSIS  OF  MILK  599 

strument  a  reading  of  15.  Milk  reading  below  39  is  certainly  watered; 
below  40  is  suspicious. 

Eefractometer  reading  is  obtained  as  follows: 

The  milk  serum  is  prepared  by  adding  3  c.  c.  of  a  25  per  cent, 
acetic  acid  (S.  G.  1.035)  to  100  c.  c.  of  milk  at  about  20°  C.  and  mixing 
well.  Heat  the  mixture  in  a  beaker  covered  with  a  watch  glass  to  70°  C. 
Maintain  this  temperature  for  20  minutes.  Cool  quickly  to  room  temper- 
ature by  means  of  cold  water,  and  filter  until  nearly  or  quite  clear.  Do 
not  discard  the  curd,  as  it  can  be  used  to  test  for  the  presence  of  artificial 
colors.  The  refractometer  reading  is  taken  with  the  filtrate  at  17.5°  C, 
this  temperature  being  maintained  by  means  of  a  large  body  of  water  at 
the  same  temperature  surrounding  the  milk  container. 

If  a  refractometer  is  not  at  hand  practically  the  same  information 
can  be  obtained  from  the  milk  serum  by  taking  its  specific  gravity  with 
a  Westphal  balance  or  a  pycnometer. 

The  specific  gravity  of  the  serum  from  normal  milk  is  never  below 
1.027  and  only  rarely  below  1.029.  The  addition  of  each  10  per  cent, 
of  water  lowers  the  specific  gravity  by  0.0010  to  0.0035. 

Reaction. — The  acidity  of  milk  is  determined  by  titration  with  a 
solution  of  sodium  hydroxid,  using  phenolphthalein  as  the  indicator. 

Take  50  c.  c.  of  milk  and  add  a  few  drops  of  alcoholic  phenolphtha- 
lein solution.  From  a  burette  run  in  0.1  normal  sodium  hydroxid  solu- 
tion with  constant  stirring  until  the  pink  color  in  the  milk  persists  about 
15  seconds.  The  carbon  dioxid  in  the  atmosphere  fades  out  the  phenol- 
phthalein color  by  converting  the  sodium  hydroxid  into  sodium  bicar- 
bonate, hence  the  determination  must  be  made  rapidly,  and  a  rather  faint 
but  not  very  permanent  pink  color  marks  the  end  point. 

The  acidity  of  milk  is  usually  expressed  in  terms  of  lactic  acid,  al- 
though when  fresh  it  is  caused  by  other  organic  acids.     To  convert  the 

amount   of  —    sodium  hydroxid   solution   necessary   to   neutralize   the 

acidity  in  50  c.  c.  of  milk  into  percentages  of  lactic  acid,  multiply  the 

TV 
number  of  cubic  centimeters  of  —  NaOH  by  0.018. 

The  results  of  these  titrations  are  recorded  in  three  different  ways : 
(1)  In  this  country  the  calculations  are  reduced  to  terms  of  lactic  acid. 

Thus,  1  c.  c.  of  — 'XaOH  neutralizes  0.02  gram  of  lactic  acid;   (2)  in 

degrees  of  acidity,  by  which  is  meant  the  number  of  cubic  centimeters  of 

N 

—  ISTaOH  required  to  neutralize  100  c.  c.  of  milk;   (3)  in  German  de- 

.   .  N 

grees  of  acidity,  meaning  the  number  of  cubic  centimeters  of  —  ISTaOH 

per  100  c.  c.  of  milk.  For  transposition  purposes  the  following  equiva- 
lents are  given : 


600  ANIMAL  FOODS:  MILK 

1  degree  (U.  S.)  of  acidity 0.009    per  cent,  lactic  acid 

1  degree  (German)  of  acidity 0 .  0225  per  cent,  lactic  acid 

1  degree  (German)  of  acidity 2.5°    (U.  S.)  acidity 

Eiihm  ^  has  recommended  the  following  test  for  detection  of  begin- 
ning acidification  in  mixed  milks  of  two  or  more  cows:  Ten  c.  c.  of 
68  per  cent,  alcohol  is  added  to  10  c.  c.  of  the  milk  to  be  tested.  If 
there  is  immediate  coagulation  the  acidity  is  above  8°.  More  advanced 
acidity  may  be  detected  by  boiling  a  small  amount  of  milk  for  a  few 
moments  in  a  test  tube.  Coagulation  appears  if  the  acidity  is  above 
10°.    These  are  convenient  tests  that  may  be  applied  at  the  dairy. 

Milk  has  a  variable  acidity  when  it  coagulates;  that  is,  when  it 
throws  its  caseinogen  out  of  solution.  Milk  containing  about  0.225  per 
cent,  of  acid  will  coagulate  upon  heating.  This  may  be  prevented  by 
first  neutralizing  with  an  alkali,  such  as  sodium  carbonate.  The  amount 
of  acidity  in  a  particular  sample  of  milk  is  no  safe  criterion  as  to 
whether  it  will  coagulate  or  not  during  pasteurization.  This  can  only 
be  determined  with  certainty  by  first  testing  a  small  portion. 

Specific  Gravity,. — The  specific  gravity  of  milk  is  taken  either  (1) 
with  the  lactodensimeter,  (2)  with  the  Westphal  balance,  or  (3)  upon 
an  ordinary  chemical  balance,  with  a  pycnometer. 

The  Quevenne  lactodensimeter  is  recommended  for  the  determi- 
nation of  the  specific  gravity.  It  is  made  like  an  ordinary  aerometer 
and  divided  into  degrees  which  correspond  to  a  specific  gravity  from 
1.014  to  1.040,  or  only  from  1.022  to  1.038,  since  by  the  latter  division 
a  greater  space  is  gained  between  the  different  degrees  without  unduly 
lengthening  the  instrument.  From  such  a  lactodensimeter  one  can  easily 
read  off  four  decimal  places. 

The  milk,  the  specific  gravity  of  which  is  to  be  determined,  is  well 
shaken  and  poured  into  a  high-class  cylinder  of  suitable  diameter;  the 
lactodensimeter  is  dropped  in  slowly,  in  order  to  prevent  its  bobbing 
up  and  down.  (The  bulb  should  be  free  from  adhering  air  bubbles.) 
The  figures  on  the  stem  are  the  second  and  third  decimals  of  the  num- 
bers of  the  specific  gravity,  so  that  34  is  to  be  read  1.034.  For  this 
examination  the  temperature  of  the  milk  must  be  15°  C.  (60°  F.) ;  if 
it  is  not,  the  specific  gravity  of  the  milk  at  15°  C.  must  be  calculated 
from  the  specific  gravity  found  and  from  the  temperature,  for  in  milk 
inspection  and  analysis  this  is  the  standard. 

Westphal  Balance. — This  instrument  is  more  accurate  than  the 
lactometer.  It  is  in  equilibrium  when  the  sum  of  the  weights  equals 
the  specific  gravity  of  the  liquid. 

To  use  this  instrument  dry  the  plummet  and  balance  the  arm  in  the 
air;  then  fill  the  cylinder  with  the  sample.  Now  place  the  plummet  in 
the  milk  and  balance  the  weights.     The  large  weights  represent  the 

^Riihm:   Zeitschr.  f.  Fleisch  u.  Milch-hyg.,  Vol.  XX,   1910. 


CHEMICAL  ANALYSIS  OF  MILK 


601 


first  decimal  place,  the  second  size  the  second  decimal  place,  the  third 
size  the  third  decimal  place,  and  the  fourth  size  the  fourth  decimal 
place.  The  specific  gravity  is  the  sum  total,  as  shown  by  the  notches  on 
the  arm  of  the  balance. 

Example  : 

Notch  Value 

Largest  size  weights 9  .9 

Second  size         "      1  .1 

Second  size        "      3  .03 

Third  size  "      2  .003 

Fourth  size         ''      4  .0004 


1.0324  =  Specific  Gravity 

Correct  for  temperature  by  means  of  the  following  table : 

Table  for  correcting  the  specific  gravity  of  milk  according  to  temperor 
ture.     (Adapted  from  the  table  of  Vieth.) 


Specific 
Gravity 

10° 

11° 

12° 

13° 

14° 

15° 

16° 

17° 

18° 

19° 

20° 

1.027 

26.1 

26.2 

26.4 

26.5 

26.7 

26.9 

27.1 

27.4 

27.5 

27.7 

28.0 

28 

27.0 

27.2 

27.4 

27.5 

27.7 

27.9 

28.1 

28.4 

28.5 

28.7 

29.0 

29 

28.0 

28.2 

28.4 

28.5 

28.7 

28.9 

29.1 

29.4 

29.5 

29.8 

30.1 

30 

29.0 

29.1 

29.3 

29.5 

29.7 

29.9 

30.1 

30.4 

30.5 

30.8 

31.1 

31 

29.9 

30.1 

30.3 

30.4 

30.6 

30.9 

31.2 

31.4 

31.5 

31.8 

32.2 

32 

30.9 

31.1 

31.3 

31.4 

31.6 

31.9 

32.2 

32.4 

32.6 

32.9 

33.2 

33 

31.8 

32.0 

32.3 

32.4 

32.6 

32.9 

33.2 

33.4 

33.6 

33.9 

34.2 

Directions:    Find  the  observed  gravity  in  the  left-hand  column. 
under  the  observed  temperature,  will  be  found  the  corrected  reading. 


Then  in  the  same  line,  and 


Taking  the  specific  gravity  of  the  whole  milk  does  not  of  itself  de- 
tect either  watering  or  skimming,  since,  if  these  practices  are  done 
artfully,  the  specific  gravity  of  the  milk  may  remain  unaltered.  The 
specific  gravity  of  normal  milk  serum  is  about  1.0287. 

Heated  Milk.— Milk  that  has  been  heated  above  79°  or  80°  C.  may 
be  detected  by  the  fact  that  the  enzymes  are  killed.  Several  methods 
are  used;  the  most  convenient,  perhaps,  is  Dupouy's  method.  A  few 
drops  of  a  freshly  prepared  solution  of  diamidobenzene  in  water  (1-4) 
and  a  little  hydrogen  dioxid  are  added  to  5  c.  c.  of  milk.  With  raw 
milk  a  coloration  appears,  while  with  milk  that  has  been  heated  to  79° 
C.  or  over  no  color  is  produced.  Other  tests,  such  as  the  Storch  method 
or  Arnold's  guaiac  method,  are  described  below  under  "Tests  for 
Enzymes." 

A  test  for  heated  milk  has  recently  been  devised  by  Frost  who  finds  that 
the  leukocytes  in  raw  milk  do  not  stain  with  methylene  blue,  whereas  these 
cells  in  heated  milk  stain  well,  especially  the  nuclei ;  and  are  smaller.^ 
V.  A.  M.  A.,  March  6,  1915,  also. 


603  ANIMAL  FOODS:  MILK 

Tests  for  Enzymes,  and  Their  Si^ificance. — The  following  tests  are 
those  most  frequently  used  : 

Catalase  Test. — Ten  c.  c.  of  the  milk  to  be  tested  is  mixed  with 
10  c.  c.  of  a  3  per  cent,  (by  volume)  hydrogen  peroxid.  The  mixture 
is  placed  in  a  Lobeck  tube  and  the  stopper  tightly  inserted.  Then  the 
tube  for  measuring  the  liberated  oxygen  is  filled  with  water  and  inserted 
into  the  perforated  stopper,  pushing  out  the  small  hard  rubber  button. 
The  mixture  of  milk  and  hydrogen  peroxid  is  immersed  up  to  the  stop- 
per in  a  water  bath  at  37°  C.  and  left  there  for  two  hours.  The  oxygen 
that  is  liberated  replaces  the  water  in  the  graduated  tube  on  which  the 
readings  are  made.  Larger  quantities  of  milk  (15  c.  c.)  and  less  hy- 
drogen peroxid  (3  c.  c.)  give  more  satisfactory  readings  for  pasteurized 
milk. 

According  to  Auzinger,  the  liberation  of  much  gas  by  this  test  oc- 
curs (1)  with  physiologically  changed  milk,  as  is  the  case  with  colos- 
trum and  with  milk  from  old  milkers ;  ( 2 )  in  the  case  of  pathologically 
changed  milk,  as  in  mastitis  and  other  febrile  diseases;  or  (3)  in  milk 
containing  a  large  number  of  bacteria. 

The  test  for  catalase,  therefore,  is  of  assistance  in  detecting  old, 
bacteria-laden,  or  abnormal  milk. 

Eeductase  Test. —  (1)  SchmidUMuller  or  Slow  Reductase  Test. — 
The  reagent  is  made  by  adding  195  c.  c.  of  distilled  water  to  5  c.  c.  of 
a  saturated  alcoholic  solution  of  methylene  blue  (zinc  chlorid  double 
salt).  This  reagent  should  be  boiled  every  day  before  using.  The 
test  is  made  by  adding  to  20  c.  c.  of  milk  in  a  test  tube  1  c.  c.  of  the 
reagent,  mixing,  sealing  with  melted  paraffin,  and  then  incubating  at 
45°  C.  in  a  water  bath.  According  to  Riihm,^  fresh  milk  remains  blue 
for  12  hours  or  more,  and  "infected"  milk  decolorizes  in  less  than  one 
hour.  Reductases,  according  to  Riihm,  are  increased  by  acid-forming 
bacteria,  but  not  by  alkaline  producers.  Auzinger,^  who  uses  0.5  c.  c. 
of  the  reagent  in  20  c.  c.  of  milk,  states  that,  on  holding  the  mixture 
at  38°  to  40°  C,  milk  not  decolorizing  in  seven  hours  contains  less 
than  100,000  bacteria  per  c.  c. ;  that  which  decolorizes  in  2  to  7  hours 
contains  100,000  to  300,000;  and  that  which  decolorizes  in  14  ^o  ^ 
hours  contains  300,000  to  20,000,000  bacteria  per  c.  c. 

(2)  Schardinger  or  Hastened  Eeductase  Test. — The  reagent  is  made 
by  adding  5  c.  c.  of  40  formaldehyd,  5  c.  c.  of  saturated  alcoholic  solution 
of  methylene  blue  (zinc  chlorid  double  salt)  to  190  c.  c.  of  distilled  water. 

The  test  is  made  by  adding  to  10  c.  c.  of  milk  2  c.  c.  of  the  reagent 
in  a  test  tube,  mixing  well,  sealing  with  melted  paraffin,  and  holding 
at  37°  C.  in  a  water  bath.  By  the  test,  according  to  Auzinger,^  good 
milk  reduces  the  color  in  8  to  12  minutes,  milk  rich  in  bacteria  reduces 

^Ruhm:    Zeit.  f.  Fl.  u.  Milch-hyg.,  Vol.    XX,   1910. 
^Auzinger:   Ibid.,  Vol.  XX,   1910. 


CHEMICAL  ANALYSIS  OF  MILK  603 

in  5  minutes  or  less,  and  when  colostrum  is  present  two  or  more  hours 
are  required. 

To  test  for  heated  milk;  add  20  c.  c.  of  the  milk  to  1  c.  c.  of  the 
reagent;  seal  with  liquid  petroleum,  and  incubate  at  45°  to  50°  C.  Eaw 
milk  will  decolorize  this  reagent  in  less  than  20  minutes;  pasteurized  milk 
will  take  a  longer  time. 

Of  the  two  reductase  tests,  according  to  Schardinger,^  reduction  by 
the  slow  method  is  due  to  ferments  produced  by  bacteria,  while  by  the 
hastened  method  reduction  is  due  to  the  natural  ferments  of  milk. 

The  slow  reductase  test  is  of  assistance  in  detecting  old  milk,  and 
the  hastened  reductase  test  offers  a  convenient  and  reliable  method  for 
detecting  and  testing  the  efficiency  of  pasteurization. 

Stokch  Test. — To  about  5  c.  c.  of  milk  in  a  test  tube  add  a  drop  of 
0.2  per  cent,  solution  of  hydrogen  peroxid  containing  0.1  per  cent,  sul- 
phuric acid,  and  2  drops  of  a  2  per  cent,  aqueous  solution  of  parapheny- 
lendiamin  hydrochlorid.  Mix.  A  positive  reaction  consists  in  the  rapid 
production  of  a  blue  or  dark-violet  color.  The  paraphenylendiamin  hy- 
drochlorid does  not  keep  well  and  should  be  recently  prepared.  If  the 
milk  is  sour  it  must  first  be  made  alkaline  with  lime  water.  Eaw  milk 
gives  a  positive  reaction  at  once:  milk  that  has  been  heated  to  boiling 
gives  no  reaction. 

Peroxidase  Eeaction. —  (a)  Eothenfusser's  Test:^  Dissolve  1 
gram  of  /^-phenylenediamin  hydrochlorid  in  15  c.  c.  of  water.  Dissolve  2 
grams  of  crystallized  guaiacol  in  135  c.  c.  of  96  per  cent,  alcohol.  Mix 
these  solutions  and  keep  in  an  amber-colored  bottle.  To  10  c.  c.  of  milk 
add  0.5  c.  c.  of  the  above  reagent  and  3  drops  of  3  per  cent,  hydrogen 
dioxid.  A  blue-violet  coloration  is  developed  in  raw  milk  and  if  the  milk 
has  been  heated  to  a  sufficiently  high  temperature  no  color  is  produced. 
This  reaction  is  scarcely  delicate  enough  to  detect  commercially  pasteur- 
ized milk. 

(b)  The  Benzidin  Test:  ^  Dissolve  4  grams  of  benzidin  in  100  c.  c. 
of  96  per  cent,  alcohol.  To  10  c.  e.  of  milk  add  1  c.  c.  of  this  reagent, 
3  drops  of  30  per  cent,  acetic  acid  and  2  c.  c.  of  3  per  cent,  hydrogen 
dioxid;  a  blue  coloration  is  produced  with  raw  milk  and  none  with  milk 
heated  to  a  sufficiently  high  temperature. 

Bellei  Test. — The  test  is  made  by  adding  to  10  c.  c.  of  milk  3 
drops  of  1.5  per  cent,  aqueous  solution  of  ortol  and  two  drops  of  3 
per  cent.  HgOg. 

REFERENCES 

Sommerfeld,  Paul:  "Handbuch  der  Milchkunde,"  J.  F.  Bergmann, 
Wiesbaden,  1909. 

^  Schardinger :     Arch.  f.  Kinderheilk.,  Bd.  58,  H.  5-6. 
"  Milchicirtschl.  Zentr.,  6,  468. 
^Z.  Nahr.  Genussm.,  16,  172. 


604  ANIMAL  FOODS:  MILK 

Swithinbank,  Harold,  and  Newman,  George:  "Bacteriology  of  Milk," 
E.  P.  Button  &  Co.,  1903. 

"Milk  and  Its  Kelation  to  the  Public  Health,"  Hyg.  Lah.  Bull.  No.  56, 
U.  S.  P.  H.  &  M.  H.  S.    Various  authors. 

Eosenau,  M.  J. :     "The  Milk  Question,"  Houghton,  Mifflin  &  Co.,  1912. 

Savage,  Wm.  G. :  "Milk  and  the  Public  Health,"  Macmillan  &  Co.,  Ltd., 
London,  1912. 

Report  of  the  Commission  on  Milk  Standards,  N.  Y.  Milk  Committee, 
Public  Health  Reports,  U.  S.  P.  H.  &  M.  H.  S.,  xxvii,  19,  May  10,  1912. 

Barthel,  Chr. :  "Die  Methoden  zur  Untersuchung  von  Milch  und  Mol- 
kereiprodukten."    Leipzig,  1911.    English  edition  translated  by  Goodwin. 

Jensen;  "Essentials  of  Milk  Hygiene."  Translated  by  Leonard  Pear- 
son.   J.  P.  Lippincott  Co.,  1907. 

Earrington  and  Woll:  "Testing  Milk  and  Its  Products,"  21st  edition, 
Mendata  Book  Co.,  Madison,  Wis.,  1912. 


CHAPTEE   III 
ANIMAL  FOODS :  MEAT,  FISH,  EGGS,  ETC. 

MEAT 


The  universal  consumption  of  meat  as  a  daily  article  of  diet  by 
civilized  man  is  of  more  recent  origin  than  is  generally  supposed. 
McCulloch  ^  states  that  "so  late  as  1763  the  slaughter  of  bullocks  for 
the  supply  of  the  public  markets  wsis  a  thing  wholly  unknown,  even  in 
Glasgow,  though  the  city  then  had  a  population  of  30,000."  In  the 
past  decade  or  two  the  consumption  of  meat  has  increased  enormously, 
especially  in  the  United  States  and  England,  owing  to  the  development 
of  cheap  refrigerator  processes,  canning,  and  increased  facilities  of  trans- 
portation. The  annual  per  capita  consumption  of  meat  has  almost 
doubled  during  the  past  half  century.^ 

Per  capita  and  proportional  consumption  of  dressed  meat  in  United  States,  United 
Kingdom,  Germany,  and  France 

[The  Twenty-eighth  Annual  Report  of  the  Bureau  of  Animal  Industry,  1911] 


Kind  of  Meat 

United  States 
(1909) 

United  Kingdom 

(Average,  1906- 

1908) 

Germany,  (1909)> 

France  (1904) 

Beef 

Veal 

Pounds 
80 

7^ 
6^ 
78 

Per  Cent. 
47 

4 

4 
45 

Pounds 

56 

4 

26 

33 

Per  Cent. 

47 

3 

22 

28 

Pounds 
36 
7V2 

2V2 

67 

Per  Cent. 
32 

7 

2 
59 

Pounds 
37 

8 

9 
26 

Per  Cent. 
46 
10 

Mutton  and  lamb 

Pork  (including  lard) . . . 

11 
33 

Total 

172 

100 

119 

100 

113 

100 

80 

100 

'  The  farm  slaughter  in  Germany  is  for  1907. 

Structure  and  Composition  of  Meats. — Meat  is  composed  of  muscular 
fibers,  and  the  structures  intimately  associated  with  them,  such  as 
connective  tissue,  blood  vessels,  nerves,  lymphatic  vessels,  and  more  or 
less  adipose  tissue. 

The  toughness  of  meat  is  due  to  the  thickness  of  the  walls  of  the 
muscle  tubes  and  excess  of  connective  tissue  which  binds  them  together, 
hence  the  flesh  of  young  domesticated  animals  is  usually  more  tender 
than  that  of  old  or  wild  animals. 

*  "Statistical  Account  of  the  British  Empire,"  Vol.  II,  p.  502. 
^  Thompson :   "Practical  Dietetics." 

605 


606  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

The  flavor  of  meat  varies  with  the  animal's  age,  its  food,  breed,  and 
condition  when  killed.  The  meat  of  male  animals  is  usually  more  highly 
flavored  than  that  of  females.  The  flesh  of  service  boars  and  of  sexually 
mature  buck  goats  is  so  highly  flavored  as  to  be  unfit  for  food. 

Meat  contains  albuminoids  and  gelatinoids;  the  latter  through  ac- 
tion of  hot  water  or  steam  are  converted  into  gelatin.  In  addition  meat 
contains  the  following  nitrogenous  substances :  syntonin,  myosin,  muscle 
albumin,  serum  albumin,  and  numerous  extractives,  such  as  creatin, 
creatinin,  xanthin,  hypoxanthin,  lactic  acid;  and  small  quantities  of 
inosit  and  glycogen. 

Meat  at  once  after  slaughter  has  an  alkaline  reaction,  is  tough,  and 
possesses  a  sweetish  and  rather  unpleasant  flavor.  Eigor  mortis  soon 
sets  in,  accompanied  by  the  following  changes :  the  reaction  of  the  meat 
turns  acid,  owing  to  the  development  of  sarcolactic  acid ;  the  connective 
tissue  and  fibers  are  softened  as  the  result  of  autolytic  enzymes  and  also 
as  a  result  of  bacterial  action.  While  the  meat  becomes  more  tender,  it 
also  develops  pleasant  flavors.  It  is,  therefore,  not  advisable  to  use  meat 
at  once  after  slaughter,  but  it  should  be  allowed  to  hang  to  or  three  weeks 
under  adequate  refrigeration.  It  is  important  during  this  time  to  pre- 
serve the  meat  from  contamination  with  pathogenic  microorganisms 
and  to  retard  the  growth  of  the  saprophytes. 

Nutritive  Value  of  Meat. — The  nutritive  value  of  meat  depends 
mainly  upon  the  presence  of  proteins  and  fats.  Nitrogenous  extractive 
matters,  such  as  creatin,  xanthin,  etc.,  sometimes  called  meat  bases, 
are  formed  by  cleavage  of  the  proteins,  but  are  of  little  value  as  foods. 
These  nitrogenous  extractives  are  present  in  about  the  same  amount 
in  both  red  and  white  meats,  with  the  single  exception  of  venison,  which 
contains  the  least  amount. 

Meat  must  be  regarded  as  a  condensed  and  expensive  food.  For 
instance,  a  steak  that  costs  twenty-five  cents  a  pound  contains  over 
one-third  or  one-half  of  inedible  substances,  so  that  the  edible  portion 
really  costs  double  that  amount.  On  the  contrary,  when  a  pound  of 
flour  or  cereal  is  purchased,  the  price  of  which  is  perhaps  only  one- 
eighth  that  of  meat,  the  whole  of  it  is  edible. 

Beef  extracts  are  nothing  more  or  less  than  a  soup  or  soup  stock 
specially  prepared  from  beef.  They  first  became  generally  known  through 
the  researches  of  Liebig,  and  are  now  an  important  article  in  commerce. 
The  composition  of  the  ordinary  beef  extract  of  commerce  contains  from 
15  to  20  per  cent,  of  moisture,  from  17  to  23  per  cent,  ash,  and  from  50  to 
60  per  cent,  of  meat  bases.  These  meat  bases  are  the  soluble  nitrogenous 
contents  of  meat.  They  contain  only  a  trace  of  soluble  albumin,  al- 
bumoses,  and  peptone.  The  chief  meat  bases  which  form  the  principal 
part  of  the  substance  are  creatin,  creatinin,  xanthin,  carnin,  and  carnic 
acid.    It  is,  therefore,  evident  that  meat  extracts  contain  little  nutritive 


MEAT  607 

matter,  although  this,  being  in  a  state  of  solution,  is  probably  more  readily 
absorbed  than  a  similar  amount  of  other  nutritives  in  the  form  of  ordi- 
nary meat.  Wiley  properly  points  out  that  the  claim  made  by  manufac- 
turers is  misleading,  in  that  one  pound  of  extract  contains  the  nutritive 
properties  of  many  pounds  of  meat.  Such  a  statement  is  absurd  upon  its 
face,  and  should  not  be  allowed  to  go  unchallenged.  These  extracts  may 
be  useful  as  stimulants  or  as  condiments,  or  as  a  means  of  speedily  intro- 
ducing a  soluble  nutrient  in  the  case  of  disease,  where  it  is  extremely 
important  that  even  small  amounts  of  nutritious  material  should  enter  the 
body. 

A  distinction  should  be  made  between  beef  extract  and  beef  juice. 
Beef  juice  is  obtained  by  strong  pressure  and  is  concentrated  in  vacuo  to 
the  proper  consistence,  or  it  may  be  freshly  prepared  in  the  household. 
Beef  juice  contains  much  more  albuminous  nutrient  material  than 
beef  extract,  provided  it  is  not  coagulated  by  heat  and  separated  out. 

Sources  of  Meat. — The  principal  source  of  meat  is  from  cattle,  sheep, 
and  swine.  In  many  places  the  flesh  of  horses,  dogs,  and  cats  is  eaten. 
In  Germany  horses  and  dogs  are  slaughtered  and  regularly  inspected 
for  human  food.  The  meat  of  these  animals  is  also  used  in  other  coun- 
tries that  have  long  been  flesh  hungry.  There  is  no  sanitary  objection 
to  the  use  of  such  meat.  Horse  meat,  when  eaten  in  ignorance  of  its  true 
character,  makes  no  unpleasant  impression.  In  Paris,  Vienna,  and 
other  cities  large  quantities  of  horses,  mules,  and  donkeys  are  slaughtered 
for  food.  It  was  formerly  difficult  to  distinguish  horse  meat,  but  this 
is  now  rendered  comparatively  easy  by  means  of  the  specific  precipitins. 
(For  this  test  see  page  454.) 

The  different  kinds  of  meat  may  be  detected  by  physical,  micro- 
scopical, chemical,  or  biological  tests.  Ordinarily  meats  from  different 
animals  may  be  distinguished  by  their  odor  or  taste.  Microscopically 
the  fibers  resemble  each  other  so  closely  that  this  test  is  not  to  be  re- 
lied upon.  Meat  varies  somewhat  in  chemical  composition  from  different 
species,  from  different  animals  of  the  same  species,  and  even  from  differ- 
ent muscles  in  the  same  animal.  The  principal  difference  in  the  chemical 
composition  of  meats  from  animals  of  different  species  consists  in  the 
glycogen  and  fat  content.  Thus,  horse  meat  contains  considerably  more 
glycogen  than  beef.  ,The  glycogen  test,  however,  is  not  reliable  because 
it  may  be  changed  as  a  result  of  bacterial  action. 

The  fats  of  different  animals  have  different  physical  and  chemical 
characteristics.  The  fats  crystallize  in  different  forms  and  have  dif- 
ferent melting  points;  also  the  fatty  acids  derived  therefrom.  A  care- 
ful examination  of  the  fat,  therefore,  will  lead  to  an  approximate  de- 
gree of  knowledge  concerning  the  character  of  the  flesh  from  which  it  has 
been  derived.  For  instance,  lard  and  beef  fat  are  easily  distingiiished 
from  each  other. 


608  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

The  Recognition  of  Spoiled  Meat.^ — The  recognition  of  spoiled  meat 
that  is  also  injuriovis  to  health  is  a  very  difficult  task.  Meat  that  is 
decomposed,  putrid,  or  offensive,  and  thus  objectionable  to  the  senses, 
needs  no  further  condemnation.  The  most  serious  infections  and  poi- 
sons in  meat,  however,  do  not,  as  a  rule,  affect  its  appearance,  odor,  or 
taste.  Certain  putrefactive  changes  brought  about  by  bacterial  action, 
which  give  the  high  or  gamy  taste  so  much  prized  by  epicures,  appear 
not  to  be  injurious.     Dogs  and  other  carnivora  prefer  putrid  flesh. 

Meat  inspectors  are  usually  instructed  to  condemn  meat  that  has 
not  a  red,  fresh  appearance,  especially  if  it  has  become  brownish  or 
greenish.  The  meat  is  to  be  condemned  if,  upon  pressure,  much  fluid 
of  abnormal  color  or  alkaline  reaction  exudes;  if  the  fat  is  not  yellow 
and  firm,  especially  if  soft  and  gelatinous;  if  the  marrow  of  the  femur 
is  not  firm  and  rose-colored  and  has  become  soft  and  brownish.  Spoiled 
meat  under  the  microscope  shows  obscurity  of  the  cross  striations  of 
the  muscle  fibers  and  numerous  bacteria.  For  a  further  discussion  of 
this  subject  see  Meat  Inspection,  and  also  the  various  diseases  which 
render  meat  unsuitable  or  injurious  as  food. 

Prevention. — The  prevention  of  infections  and  poisoning  from  meat 
and  meat  products  depends,  first  of  all,  upon  the  health  of  the  animal, 
next  upon  the  mode  of  death,  and  finally  the  methods  of  butchering, 
preserving,  and  handling  the  flesh.  Careful  attention  to  every  detail 
is  necessary  all  along  the  line.  Cleanliness  approaching  surgical  methods 
on  the  part  of  the  butcher  during  the  preservation,  transportation,  and 
preparation  of  the  meat  is  called  for.  A  careful  system  of  meat  inspec- 
tion is  a  good  sanitary  safeguard.  Thorough  cooking  is  the  most  im- 
portant protection  we  have  against  infection. 

Meat  should  never  be  eaten  raw,  even  where  there  is  a  carefully  con- 
ducted inspection  by  trained  experts.  Individual  cysticerci  (tapeworm 
larvae)  are  very  easily  overlooked,  and  one  is  enough  to  bring  forth  a 
tapeworm.  It  is  also  not  possible  to  examine  all  hogs,  particularly  those 
slaughtered  in  country  districts,  for  trichina,  and  even  where  this  is 
done  with  care  the  method  does  not  afford  complete  protection.  It  should 
further  be  remembered  that  some  of  the  more  serious  bacterial  infections 
do  not  alter  the  color,  taste,  or  appearance  of  the  meat  in  any  way. 
Eaw  meat  does  not  have  a  higher  nutritive  value  than  cooked  meat,  and 
is  no  more  easily  digested. 

Special  measures  of  prevention  will  be  discussed  under  each  in- 
fection. 

Meat  Preservatives. — The  regulations  of  the  U.  S.  Department  of 
Agriculture  permit  the  addition  to  meat  or  meat  food  products  of  the 
following  substances:  common  salt,  sugar,  wood  smoke,  vinegar,  pure 
spices,  saltpeter,  benzoate  of  soda,  which  must  be  declared  on  the  label. 

*  See  "Meat  Industry  and  Meat  Inspection,"  Leighton  and  Douglas. 


MEAT  609 

Only  such  coloring  matters  as  may  be  designated  by  the  Secretary  of' 
Agriculture  may  be  used. 

The  adulterants  most  commonly  used  in  meats  are  saltpeter,  boracic 
acid,  borax,  sulphite  of  soda,  and  benzoic  acid. 

MEAT    INSPECTION  1 

The  necessity  for  a  careful  sanitary  control  of  our  food  is  growing 
greater  year  by  year  in  order  to  protect  the  consumer.  This  is  especially 
necessary  in  the  case  of  animal  food  products,  particularly  meat  and 
milk,  which  are  most  apt  to  carry  infections  and  are  the  most  readily 
decomposable.  The  necessity  for  this  inspection  is  accentuated  by  the 
fact  that  the  producer  and  the  consumer  are  often  separated  by  great  dis- 
tances, and,  further,  there  are  several  middlemen  between  the  two.  The 
•ignorance  or  greed  of  the  middleman  or  the  producer  may  force  upon 
the  consumer  meat  that  is  injurious  or  that  is  considerably  below 
value. 

The  danger  does  not  consist  alone  in  eating  infected  or  decayed 
animal  products;  the  mere  handling  of  flesh  of  some  animals  having 
had  anthrax  or  glanders  may  be  sufficient  to  transmit  infection  to  the 
butcher  or  housewife.  An  efficient  meat  inspection  system  is  not  only 
of  advantage  to  man,  but  is  the  means  of  detecting  and  preventing 
disease  among  cattle,  sheep,  and  swine.  A  sharp  outlook  at  the  slaughter 
house  will  discover  the  first  appearance  of  rinderpest,  foot-and-mouth 
disease,  Texas  fever,  or  other  epizootic,  which  may  then  be  quickly  traced 
to  its  origin  and  nipped  in  the  bud. 

The  border  line  between  health  and  disease  is  ill-defined.  It  is 
doubtful  whether  any  animal  slaughtered  for  food  is  wholly  sound  and 
free  from  disease.  Parasitic  infections  among  the  lower  animals  are 
exceedingly  common.  Anyone  may  convince  himself  of  this  fact  by  a 
visit  to  a  slaughter  house,  for  there  he  will  see  that  many  hogs  have  a 
handful  of  round  worms  in  the  intestinal  tract;  most  animals  have  one 
or  more  species  of  intestinal  worms,  such  as  hookworms,  tapeworms,  and 
many  protozoa,  but,  fortunately,  these  are  for  the  most  part  not  dangerous 
to  man.  Almost  every  hog  or  beef  that  is  killed  contains  a  sarcosporidia, 
a  small  parasite  that  inhabits  only  the  muscles  of  these  animals  and 
which  is  harmless  to  man.  It  is,  therefore,  at  once  evident  that  the  line 
in  meat  inspection  cannot  be  drawn  between  health  and  disease,  but 
aims  to  eliminate  those  diseases  which  are  injurious  to  man  and  those 
diseases  and  conditions  which  render  the  meat  of  inferior  quality  or 
otherwise  unfit  for  use.     In  establishing  correct  principles  to  guide  a 

^Collateral    reading:    Edlemann,    "Meat    Hygiene."      Translated   by    Mohler 
and  Eichhorn,  Lea  &  Febinger,  1911.     Ostertag,  "Handbuch  der  Fleischbeschau," 
Stuttgart,  8th  Edition,  1914. 
21 


610  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

meat  inspection  service  sentiment  must  give  way  to  science.  The  killing 
of  animals  and  the  dressing  of  the  carcasses  is  not  a  kid-glove  lousiness. 
In  our  country  much  good  meat  is  condemned  and  destroyed  according 
to  law  as  a  result  of  supersensitiveness.  When  meat  becomes  scarcer  and 
prices  higher  this  waste  will  be  checked  by  closer  adherence  to  a  sound 
application  of  pathology.  McCabe  estimates  that  the  value  of  the  car- 
casses or  parts  of  carcasses  destroyed  for  food  by  federal  inspection  dur- 
ing the  course  of  one  year  is  more  than  $2,500,000.  Dyson  places  the 
loss  at  about  three  million  to  three  and  a  half  million  annually. 

The  principles  of  meat  inspection  vary  in  different  countries,  de- 
pending upon  the  local  conditions.  Thus,  in  Germany  and  other  Euro- 
pean countries,  which  have  long  had  a  scarcity  of  meat,  and  the  people 
are,  therefore,  flesh  hungry,  much  meat  is  passed  for  food  that  would 
here  be  condemned.  In  countries  where  meat  is  not  very  abundant  it 
is  even  necessary  for  the  officials  to  keep  a  sharp  watch  to  prevent  the 
people  from  eating  meat  known  to  be  injurious.  In  America  our  attitude 
is  very  different,  for  we  have  a  repugnance  even  against  meat  known  to 
contain  a  harmless  parasite.  The  records  of  the  sanitary  sciences  are 
full  of  illustrations  of  the  consumption  of  meat  from  animals  known  to 
be  diseased. 

A  meat  inspection  service  should  have  for  its  object  first  of  all  the 
protection  of  the  consumer  against  diseased  or  other  injurious  quali- 
ties contained  in  the  meat.  This  should  be  accomplished  with  as  little 
waste  of  food  products  as  practicable,  and,  finally,  the  meat  should 
be  so  labeled  that  the  consumer  may  know  just  what  he  is  buying. 

The  Abattoir. — So  long  as  animals  are  permitted  to  be  slaughtered 
in  any  barn  or  cellar  it  is  impossible  to  exercise  a  proper  control  over 
meat  and  meat  products,  and  filthy  conditions  which  endanger  the 
public  health  will  prevail.  The  first  essential  of  a  good  meat  inspection 
service  is  to  concentrate  all  slaughtering  in  large  central  sanitary  abat- 
toirs. This  simplifies  the  inspection  and  sanitary  control,  and  is  a 
needed  measure  to  protect  the  consumer.  In  Germany  and  England 
public  abattoirs  have  been  established  which  belong  to  the  city.  These 
structures  are  built  thoroughly  of  brick  and  concrete,  and  they  are 
well  protected  against  rats.  They  are  situated  near  a  railroad,  so  as  to 
facilitate  transportation,  and  are  so  constructed  that  they  may  be  kept 
clean.  Each  person  who  wishes  to  slaughter  must  obtain  a  permit 
and  pay  rent.  In  the  entire  city  of  Paris  there  are  only  three  slaughter 
houses.  The  erection  and  maintenance  of  sanitary  slaughter  houses 
is  one  of  the  needs  of  our  country,  especially  in  the  smaller  towns,  and 
until  this  reform  is  accomplished  we  shall  never  have  a  satisfactory 
solution  of  the  meat  problem. 

An  abattoir  must  be  especially  well  constructed  and  kept  clean.  The 
same  may  be  said  of  the  trucks,  drays,  and  all  objects  that  come  in  con- 


MEAT  611 

tact  with  the  meat.  The  water-closets,  toilet-rooms,  and  dressing-rooms 
should  be  entirely  separated  from  the  departments  in  which  the  carcasses 
are  dressed  or  meat  products  handled  or  prepared.  Attention  must  be 
paid  to  eliminate  all  sources  of  odor  that  may  contaminate  the  meat,  and 
every  effort  must  be  made  to  keep  out  flies  and  other  vermin,  especially 
rats  and  mice.  Dogs  should  not  be  allowed  around  slaughter  houses  on 
account  of  the  danger  of  trichinosis  and  other  parasites.  The  feeding 
of  hogs  on  the  refuse  of  slaughter  houses  should  not  be  permitted. 

The  employees  themselves  must  be  cleanly  and  should  wear  clean 
outer  clothes  that  may  be  readily  laundered.  The  federal  regulations 
even  prescribe  that  employees  shall  pay  particular  attention  to  the  cleanli- 
ness of  their  boots  and  shoes.  It  is  just  as  important  to  wash  the  hands 
before  beginning  work,  and  to  be  particular  after  each  visit  to  the  toilet 
in  the  slaughter  house  or  butcher  shops,  as  it  is  in  the  milk  industry. 
Persons  with  tuberculosis  or  other  communicable  disease  should  not  be 
permitted  in  any  department  of  the  work  where  the  meat  or  meat  products 
are  handled  or  prepared  in  any  way.  It  is  important  that  butchers  who 
handle  a  diseased  carcass  should  thoroughly  cleanse  their  hands  of  all 
grease  and  then  immerse  them  in  a  good  disinfecting  solution.  Butchers' 
implements  used  on  diseased  carcasses  should  be  sterilized  in  boiling  water 
or  strong  carbolic  acid  or  formalin  solution  and  thoroughly  cleansed 
before  they  are  again  used.  The  federal  meat  inspectors  are  required  to 
furnish  their  own  implements  for  their  own  dissection  or  examination  of 
diseased  carcasses  or  unsound  parts.  The  precautions  required  in  an 
abattoir  and  butcher  shop  are  based  on  the  same  principles  necessary  in 
a  surgical  clinic.  Meat  that  falls  upon  the  floor  or  otherwise  becomes 
soiled  is  required  to  be  removed  and  condemned.  Inflation  by  air  from 
the  mouth  should  not  be  permitted,  inflation  by  mechanical  means  is 
also  prohibited  by  the  Department  of  Agriculture.  Only  good,  clean, 
and  wholesome  water  and  ice  should  be  used  in  the  preparation  of  the 
carcasses,  and  the  wagons  and  cars  and  all  surfaces  with  which  the 
meat  comes  in  contact  should  be  kept  clean  and  in  good  sanitary  con- 
dition. There  is  no  objection  to  the  use  of  the  skin  and  hoofs  of  animals 
condemned  for  tuberculosis  and  other  diseases  (except  anthrax)  com- 
municable to  man,  provided  they  are  disinfected.  Each  skin  and  hide 
must  be  immersed  for  not  less  than  five  minutes  in  a  5  per  cent,  solution 
of  aqua  cresolis  compositus  or  a  5  per  cent,  solution  of  carbolic  acid 
or  a  1-1,000  solution  of  bichlorid  of  mercury. 

Every  complete  abattoir  must  be  provided  with  a  retaining  room, 
a  condemned  room,  and  a  tank  room.  The  retaining  room  is  a  separate 
compartment  set  apart  for  the  final  inspection  of  all  carcasses  and 
parts  which  the  inspector  desires  to  examine  more  carefully  at  his 
leisure.  The  retaining  room  must  be  large  enough  to  have  carcasses 
hang   separately,   furnished   with   abundant   light,    and   provided   with 


613  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

sanitary  tables  and  other  necessary  apparatus.  The  condemned  room 
must  be  securely  ratproof  and  be  under  the  lock  and  seal  of  the  inspector. 
The  object  of  this  room  is  to  contain  all  carcasses  and  parts  of  car- 
casses until  they  can  be  tanked  or  disposed  of  in  accordance  with 
instructions. 

All  condemned  carcasses  or  parts  of  carcasses  are  tanked  under  special 
requirements  in  an  official  abattoir.  Tanking  consists  in  exposing  the 
carcasses  to  steam  under  a  pressure  of  not  less  than  40  pounds,  producing 
a  temperature  of  288°  F.,  and  maintained  not  less  than  six  hours.  This 
effectively  renders  the  contents  of  the  tank  unfit  for  any  edible  product. 
In  the  absence  of  tanking  facilities  the  condemned  meat  may  be  slashed 
with  a  knife  and  then  denatured  with  crude  carbolic  acid,  kerosene,  or 
other  agent,  when  it  may  be  removed  to  some  other  establishment  having 
proper  tanking  facilities. 

Qualifications  of  a  Meat  Inspector. — A  corps  of  thoroughly  trained 
meat  inspectors  is  one  of  the  most  important  links  in  the  chain  of  an 
efficient  meat  inspection  system.  A  meat  inspector  should  be  a  quali- 
fied veterinarian,  having  special  experience  and  training  for  his  specialty. 
He  must  know  the  anatomy  of  the  various  food-producing  animals, 
especially  cattle,  horses,  swine,  sheep,  and  also  fowl,  and  must  be  ac- 
quainted with  the  normal  parts  of  each.  He  must  be  able  to  distinguish 
between  the  various  organs  of  the  various  species,  so  that  he  cannot  be 
imposed  upon  by  those  who  would  like  to  substitute  one  for  another. 
He  must  know  how  to  examine  animals  during  life,  in  order  to  deter- 
mine whether  they  are  healthy.  He  must  know  the  character  of  all 
the  infectious  diseases  which  are  likely  to  pass  through  the  district  where 
he  is  situated.  The  government  recognizes  that  it  requires  a  high  degree 
of  skill  to  conduct  this  work,  and  it  has,  therefore,  placed  the  meat  in- 
spection service  under  the  Civil  Service,  and,  further,  will  admit  veter- 
inarians only  if  graduates  of  recognized  veterinary  colleges.  In  addition 
they  are  required  to  pass  a  Civil  Service  examination.^ 

The  Freibank  or  Three-Class  Meat  System. — In  Germany  and  certain 
other  European  countries  meats  are  divided  into  three  classes,  viz.,  a 
first  class,  including  meats  which  are  passed  for  unrestricted  trade;  a 
second  class,  or  Freibank  meats,  including  meats  which  are  allowed 
on  the  market  under  certain  restrictions;  and  a  third  class,  including 
meats  which  are  condemned  and  thus  excluded  from  the  food  supply. 

The  federal  meat  inspection  system  of  our  country  is  essentially  a 
two-class  meat  system,  that  is,  meats  coming  to  inspection  are  either 
passed  for  unrestricted  trade  or  they  are  condemned  and  thus  excluded 
from  use  as  food.    A  third  class  is  now  being  recognized. 

The  system  of  the  German  Freibank  and  the  compulsory  declaration 

*  There  is  also  a  large  force  of  laymen  experienced  in  curing,  canning, 
packing  and  otherwise  preparing  of  meats  and  experienced  in  the  inspection 
of  products. 


MEAT  613 

of  the  condition  of  inferior  meats  are  very  old.  The  municipal  laws  of 
Augsberg  as  long  ago  as  1276  prescribed  that  inferior  meat  should  not 
be  sold  without  giving  notice  as  to  its  quality.  In  1404  the  municipal 
laws  of  Wimpfen  provided  that  the  Freibanh  (from  the  German  frei, 
free,  here  in  the  sense  of  unconnected  or  separate,  and  lianTc,  a  counter 
or  stall)  should  be  situated  three  paces  aAvay  from  the  regular  counters. 
The  Freibank  is,  therefore,  a  counter  which  is  free  or  separate  from 
the  counters  on  which  the  first  class  meats  are  sold.  The  term 
"Finnenhanh"  is  sometimes  used  for  these  special  meat  stalls  because 
measly  meat  or  "finneges  Fleiscli"  especially  is  sold  at  these  places.  This 
system  of  the  Freibanh  has  been  extended  quite  generally  in  Germany  and 
is  rapidly  extending  in  France,  Belgium,  Italy,  and  other  European 
countries.  Meat  from  tuberculous  animals,  from  animals  containing 
cysticerci  (the  larval  stage  of  tapeworms),  trichinous  meat,  and  meat 
that  would  otherwise  be  injurious  if  eaten  raw,  but  is  entirely  safe 
as  far  as  these  infections  are  concerned  when  thoroughly  cooked,  is  first 
sterilized  by  steam  before  it  is  placed  upon  the  FreibanJc.  It  has  been 
the  more  or  less  general  experience  that  the  introduction  of  the  Freibank 
system  has  at  first  been  met  with  by  prejudice  from  various  sides,  but 
it  is  also  the  experience  that  this  prejudice  gradually  wears  off,  and  that 
in  some  places  the  demand  for  this  meat  becomes  greater  than  the  supply. 
In  any  event,  no  large  quantity  of  such  meat  should  be  sold  to  any  one 
purchaser,  so  as  to  prevent  its  being  used  to  any  great  extent  in  boarding 
houses  and  restaurants. 

Emergency  Slaughter. — In  Germany  the  system  known  as  emergency 
slaughter  or  Nothschlachtung  has  developed  to  large  proportions.  Ani- 
mals that  are  sick  or  injured  are  killed,  examined,  and,  if  suitable  for 
food,  are  labeled,  inspected,  and  passed.  In  this  way  much  valuable 
foodstuff  is  saved  that  would  otherwise  be  lost.  It  is  said  that  over 
1  per  cent,  of  the  animals  killed  for  food  in  Germany  come  under  this 
emergency  rule.  There  is  also  a  certain  amount  of  what  may  be  termed 
emergency  slaughter  going  on  in  the  local  uninspected  slaughter  houses 
of  America,  but  it  is  not  countenanced  by  the  law,  and  is,  therefore, 
done  in  secrecy.  In  this  way  the  consumer  buys  inferior  meat  of  third  or 
fourth  quality  often  at  first  class  prices.  In  Germany  the  meat  of  ani- 
mals killed  under  the  emergency  laws  is  so  labeled  and  sold  as  second 
quality. 

Methods  of  Slaughter. — In  slaughtering,  the  principal  indications 
are:  (1)  a  sudden  and  painless  death;  (2)  an  immediate  withdrawal 
of  the  blood;  (3)  removal  of  intestines  and  hair  or  hide;  (4)  immediate 
cooling.  Animals  should  be  kept  without  food  for  at  least  twelve 
hours  before  slaughter.  Sheep  and  hogs  are  usually  hung  by  the  hind 
feet  and  the  large  vessels  of  the  neck  dexterously  cut  with  a  sharp 
knife  and  with  a  single  motion  of  the  hand.     Cattle  are  usually  first 


614  ANIMAL  FOODS:  MEAT,  FTSH,  ECCJS,  ETC. 

stunned  by  a  blow  upon  the  head,  then  hung  up  by  the  hind  legs  and 
bled. 

The  Jewish  method  of  slaughtering  is  regarded  by  many  as  superior 
to  any  other.  It  consists  in  cutting  all  the  large  vessels  of  the  neck  with 
one  cut  of  a  long,  keen  knife.  The  method  is  part  of  a  ritual  which 
includes  an  inspection  of  the  animal  and  its  organs  for  evidence  of 
disease,  according  to  the  Mosaic  laws.  This  is  the  oldest  system  of  meat 
inspection.  According  to  Dembo  ^  it  is  the  most  rational  from  a  hygienic 
standpoint,  since  the  animal  is  bled  rapidly  and  completely,  and  the 
convulsive  movements  cause  the  meat  to  be  more  tender  and  of  more 
attractive  appearance.  Eigor  mortis  comes  on  more  quickly,  and  the 
meat  is,  therefore,  more  quickly  available  for  use,  and  also  will  keep 
several  days  longer  than  ordinarily. 

A  process  of  slaughtering  originating  in  Denmark  appears  to  have 
borne  the  test  of  trial  in  a  very  satisfactory  manner,  and  recommends 
itself  for  adoption  in  the  tropics,  where  meats  decompose  with  exceed- 
ing rapidity.  The  animal  is  shot  in  the  forehead  and  killed,  or  stunned, 
and  as  it  falls  an  incision  is  made  over  the  heart  and  the  ventricle 
is  opened  for  two  purposes :  to  allow  the  blood  to  escape  and  to  admit 
of  the  injection  of  a  solution  of  salt  through  the  blood  vessels  by  the 
aid  of  a  powerful  syringe.  The  process  requires  but  a  few  minutesj 
and  the  carcass  may  be  cut  up  at  once. 

The  common  methods  of  killing  fowl  intended  for  the  market  are 
either  by  bleeding,  by  dislocation  of  the  neck,  or  by  chopping  off  the 
head.  When  the  neck  is  stretched  and  dislocated  the  skin  remains 
unbroken  and  no  bruised  effect  is  produced,  but  most  of  the  blood  in  the 
body  drains  into  the  neck  and  remains  there.  In  killing  a  fowl  by  bleed- 
ing the  common  procedure  is  to  string  it  up  by  the  legs  with  the  head 
hanging  downward.  The  operator  then  gives  it  a  sharp  blow  with  a 
stick  on  the  back  of  the  head,  and  when  he  has  stunned  it  by  this  means 
he  then  inserts  a  sharp  knife  into  the  roof  of  the  mouth,  which 
penetrates  the  brain.  He  also  severs  the  large  vessels  of  the 
throat  by  rotating  the  knife,  and  the  bird  rapidly  bleeds  to 
death. 

The  TJnited  States  Meat  Inspection  Law. — The  Federal  Meat  Inspec- 
tion Law,  approved  June-  30,  1906,  provides  for  the  inspection  of  cattle, 
sheep,  goats,  and  swine,  the  meats  or  meat  food  products,  which  are 
to  enter  into  interstate  or  export  trade.  It  is  administered  by  the  Bureau 
of  Animal  Industry  under  the  direction  of  the  Secretary  of  Agriculture. 
It  should  be  remembered  that  the  Federal  Meat  Inspection  Law  applies 
only  to  meat  and  meat  products  sold  in  interstate  commerce  or  for  export 
trade,  and  does  not  apply  to  meats  butchered,  dressed,  and  sold  within 

^  Deutsche     Vierteljahresschrift    fur    offentliche     Gesundheitspflege.     XXVI, 
p.  688. 


MEAT  615 

the  state.^  In  accordance  with  our  dual  form  of  government,  the 
inspection  of  meat  that  is  slaughtered,  dressed,  and  sold  within  the 
borders  of  a  single  state  is  left  entirely  to  the  authority  of  that  state.  It 
is  not  until  some  of  this  meat  passes  the  state  line  that  it  enters  inter- 
state traffic  and  comes  under  the  provisions  of  the  federal  law.  Some 
of  the  states  have  passed  laws  similar  to  the  federal  law  to  protect 
their  own  citizens.  In  this  way  a  more  or  less  uniform  method  of  meat 
inspection  is  gradually  extending  throughout  the  country. 

The  federal  law  provides  for  the  inspection  of  the  slaughter  houses, 
the  packing  houses,  the  meat-canning,  salting,  rendering,  or  similar 
establishments;  for  the  inspection  of  animals  before  and  after  they  are 
slaughtered  and  for  the  condemnation  and  destruction  of  diseased  car- 
casses or  parts  of  carcasses.  It  also  takes  cognizance  of  the  sanitary 
conditions  of  the  establishments  and  the  health  of  the  employees.  The 
carcasses  are  either  passed  and  labeled  "inspected  and  passed,"  or  con- 
demned in  whole  or  in  part  to  the  tank,  where  they  are  steamed  or 
denatured  and  reduced  to  inedible  grease. 

Ante-mortem  Inspection,. — A  careful  ante-mortem  examination  or  at 
least  an  inspection  of  all  cattle,  sheep,  swine,  goats,  etc.,  about  to  be 
slaughtered  should  be  made  by  a  competent  veterinarian.  Any  animal 
showing  symptoms  of  or  suspected  of  being  infected  with  a  disease  or 
condition  which  would  probably  cause  its  condemnation  when  slaugh- 
tered should  be  set  aside.  These  animals  should  then  be  slaughtered 
separately  in  a  place  provided  for  this  special  purpose.  If  necessary 
the  temperature  of  the  animal  may  be  taken  in  the  ante-mortem  examina- 
tion, although  due  allowance  must  be  made  for  rise  in  temperature  due 
to  excitement  and  undue  exertion,  especially  in  hogs.  Animals  com- 
monly termed  "downers"  or  crippled  animals  are  set  aside  and  slaughtered 
separately. 

Post-mortem  Inspection. — The  post-mortem  inspection  is  nothing 
more  or  less  than  a  well-conducted  autopsy.  The  head,  tongue,  tail, 
thymus  gland,  and  all  viscera,  and  also  tlie  blood  and  all  parts  used 
in  the  preparation  of  food  and  medicinal  products  should  be  retained 
in  such  a  manner  as  to  preserve  their  identity  until  the  post-mortem 
examination  is  completed.  It  is,  of  course,  impracticable  to  formulate 
rules  to  cover  all  conditions  and  diseases,  and  much  must,  therefore,  be 
left  to  the  Judgment,  experience,  and  training  of  the  veterinary  inspector 
in  charge.  Carcasses  or  parts  of  carcasses  with  the  following  diseases 
or  conditions  are  condemned,  depending  upon  circumstances:  anthrax, 
pyemia  and  septicemia,  vaccinia,  rabies,  tetanus,  malignant  epizootic 
catarrh,  hog  cholera  and  swine  plague,  actinomycosis,  caseous  lympha- 
denitis, tuberculosis,  Texas  fever,  parasitic  icterus,  hematuria,  mange 

^  Nevertheless  an  immense  amount  of  meat  slaughtered,  shipped,  sold  and 
consumed  wholly  within  a  single  state  comes  under  Federal  inspection. 


616     ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

or  scab,  trichinosis,  tapeworms,  infections  that  may  cause  meat  poison- 
ing, icterus,  uremia,  and  sexual  odor,  urticaria,  melanosis,  tumors, 
bruises,  abscesses,  liver  flukes,  and  other  parasites,  emaciation  from 
anemia,  immaturity,  milk  fever,  and  railroad  sickness.  A  few  of  these 
diseases  deserve  brief  mention. 

Tuberculosis. — Tuberculosis  is  exceedingly  common  in  cattle  and 
is  becoming  more  and  more  prevalent  among  hogs.  A  preponderating 
percentage  of  all  carcasses  condemned  as  unfit  for  food  is  so  condemned 
on  account  of  tuberculosis.  Thus,  33,001  cattle  or  .461  per  cent.,  and 
47,632  swine,  or  .147  per  cent.,  were  condemned  for  tuberculosis  in  the 
United  States  in  1913.  Tuberculosis  is  important,  not  alone  because  so 
many  food  animals  are  infected  with  it,  but  because  it  presents  a 
peculiarly  difficult  problem  for  the  meat  inspector.  The  fundamental 
thought  in  determining  whether  to  pass  or  condemn  meat  of  a  tuberculous 
animal  is  that  it  should  not  contain  tubercle  bacilli,  and  should  not  be 
impregnated  with  toxic  substances  of  tuberculosis  or  associated  with 
septic  infection.  If  the  lesions  are  localized  and  not  numerous,  if  there 
is  no  evidence  of  distribution  of  tubercle  bacilli  throughout  the  blood, 
and  if  the  animals  are  well  nourished  and  in  good  condition,  there  is  no 
reason  to  suspect  that  the  flesh  is  unwholesome,  and  it  is  permitted 
to  be  used  after  the  removal  of  the  infected  portions.  Just  when  tu- 
berculosis should  be  considered  localized  or  generalized,  from  the  stand- 
point of  meat  inspection,  is  frequently  a  difficult  question  to  determine. 
Fortunately,  the  danger  from  this  source  is  not  very  great,  as  tuberculosis 
of  muscle  is  exceedingly  rare,  and  the  further  safeguard  of  cooking  is  suffi- 
cient to  kill  the  tubercle  bacilli,  provided  the  meat  is  thoroughly  cooked 
throughout.  The  relation  of  bovine  tuberculosis  to  human  tuberculosis 
has  been  discussed  on  page  136. 

Tuberculosis  of  cattle  shows  itself  in  four  primary  lesions :  ( 1 )  the 
retropharyngeal  lymph  nodes,  (2)  the  lungs  and  associated  lymph  nodes, 
(3)  the  mesenteric  lymph  nodes,  and  (4)  the  liver.  From  the  retro- 
pharyngeal nodes  the  process  extends  to  the  cervical  lymph  nodes  and 
also  to  the  anterior  mediastinal  lymph  nodes.  When  this  group  of 
glands  alone  is  infected  the  disease  may  be  considered  as  localized. 
From  the  mesenteric  lymph  nodes  the  infection  frequently  reaches  the 
peritoneum,  and  from  the  bronchial  lymph  nodes  the  pleura.  The  newly 
formed  growth  in  the  peritoneal  or  pleural  cavities  may  be  enormous 
in  amount.  It  is  often  suspended  from  the  omentum  in  great  grape-like 
masses  (Perlsucht),  or  the  intestines  may  be  plastered  with  tubercles. 
In  these  cases  the  animal  otherwise  may  be  in  good  condition ;  that  is, 
the  disease  is  still  outside  the  vital  organs  and  the  tubercle  bacilli 
have  not  invaded  the  blood  stream.  In  Germany  it  is  permitted  to  cut 
off  such  growth  and  allow  the  meat  to  go  into  consumption.  In  our 
country  the  meat  of  such  animals  is  rejected. 


MEAT  617 

For  practical  purposes  it  is  necessary  to  formulate  definite  rules 
for  the  guidance  of  the  veterinary  inspector,  and  this  is  done  with  minute 
particularity  in  the  regulations  of  the  Bureau  of  Animal  Industry  in  the 
case  of  tuberculosis.  In  general,  if  the  tuberculous  lesions  are  limited 
to  a  single  part  or  organ  of  the  body  without  evidence  of  recent  invasion 
of  tubercle  bacilli  into  the  general  circulation,  the  diseased  parts  are 
removed  and  the  remainder  of  the  carcass  is  passed  for  use.  If  the 
animal  suffered  from  fever  before  it  was  killed  or  is  cachectic,  anemic, 
and  emaciated,  or  if  the  lesions  are  generalized,  especially  if  they  exist 
in  two  or  more  body  cavities,  or  if  the  lesions  are  found  in  the  muscles, 
intermuscular  tissues,  bones,  or  joints,  or  if  the  lesions  are  multiple, 
acute,  and  actively  progressive,  the  carcass  is  condemned. 

Anthrax. — All  carcasses  showing  lesions  of  anthrax,  regardless  of 
the  extent  of  the  disease,  are  condemned  and  immediately  incinerated. 
This  includes  the  hide,  hoofs,  horns,  viscera,  fat,  blood,  and  all  portions 
of  the  animal.  The  killing  bed  upon  which  the  animal  was  slaughtered 
must  then  be  disinfected  with  a  10  per  cent,  solution  of  formalin,  and 
all  knives,  saws,  and  other  instruments  that  have  come  in  contact  with 
the  infection  must  be  boiled  or  otherwise  disinfected. 

Hog  Cholera  and  Swine  Plague. — Carcasses  showing  well-marked 
and  progressive  lesions  of  these  diseases  in  any  organ  or  tissue  are 
condemned.  If  the  lesions  are  slight  and  limited  they  may  be  passed  for 
lard.     Man  is  not  susceptible  to  hog  cholera. 

Actinomycosis. — If  the  animal  is  in  a  well-nourished  condition  and 
the  disease  has  not  extended  from  a  primary  area  of  infection  in  the 
head,  the  head,  including  the  tongue,  is  condemned  and  the  remaining 
part  of  the  carcass  may  be  used,  but  if  the  disease  is  generalized  the 
entire  carcass  is  considered  unfit  for  human  use  and  condemned. 

Tapew^orm  Cysts. — Carcasses  of  animals  affected  with  tapeworm 
cysts,  known  as  Cysticercus  hovis,  are  condemned  if  the  infestation  is 
excessive  or  if  the  meat  is  watery  or  discolored.  Carcasses  showing  a 
slight  infestation  may  be  passed  for  food  after  removal  and  condemna- 
tion of  the  cysts,  provided  the  carcasses  are  then  held  in  cold  storage 
or  pickle  for  not  less  than  21  days;  the  time  in  storage  may  be  reduced 
to  6  days  if  the  temperature  does  not  exceed  15°  F.  Calves  under  6 
weeks  old  are  not  subject  to  Cysticercus  hovis. 

Carcasses  or  parts  of  carcasses  found  infected  with  hydatid  cysts 
(echinococcus)  may  be  passed  after  condemnation  of  the  infected  part 
or  organ. 

Septic  and  Pyemic  Conditions. — All  carcasses  of  animals  so  iu"- 
fected  that  consumption  of  the  meat  or  meat  food  products  thereof  may 
give  rise  to  meat  poisoning  should  be  condemned.  For  the  information 
of  the  inspector  the  following  conditions  are  specified:  (1)  acute  inflam- 
mation of  the  lungs,   pleura,   peritoneum,   pericardium,   or   meninges; 


618 


ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 


(2)  septicemia  or  pyemia,  whether  puerperal  or  traumatic  or  without 
any  evident  cause;  (3)  severe  hemorrhagic  or  gangrenous  enteritis  or 
gastritis;  (4)  acute  diffuse  metritis  or  mammitis;  (5)  polyarthritis; 
(6)  phlebitis  of  the  umbilical  veins;  (7)  traumatic  pericarditis;  (8) 
any  other  inflammation,  abscess,  or  suppurating  sore  if  associated  with 
acute  nephritis,  fatty  and  degenerated  liver,  swollen  soft  spleen,  marked 
pulmonary  hyperemia,  general  swelling  of  the  lymphatic  glands,  and 
diffuse  redness  of  the  skin,  either  singly  or  in  combination. 

It  is  required  that,  immediately  after  the  slaughter  of  any  animal 
so  diseased  as  to  require  its  condemnation,  the  premises  and  implements 
used  must  be  thoroughly  disinfected.  The  part  of  any  carcass  coming 
in  contact  with  the  carcass  of  any  diseased  animal  or  with  the  place 
where  such  animal  was  slaughtered,  or  with  the  implements  used  in 
the  slaughter,  before  thorough  disinfection  has  been  accomplished,  should 
also  be  condemned. 

Diseases  and  conditions  for  which  condemnations  were  made  on  post-mortem  inspection, 

fiscal  year  1913 

[Report  of  the  Chief  of  the  Bureau  of  Animal  Industry,  Annual  Report,  Dept.  of  Agriculture,  1913] 


Cattle 

Calves 

Swine 

Sheep 

Goats 

Causes  of  Condemnation 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

Car- 
casses 

Parts 

33,101 
380 

47,554 
70,840 

450 
3 

410 
589 

47,630 

359,047 

1 

2,340 

14 

88,547 
1,715 

10,228 

40 

Tumors  and  abscesses. . . 
Septicemia,  pyemia,  and 

232 

1,501 

371 

3,789 

20 
266 

185 

3,830 

106 
876 
104 

55 

1 
7 

1 

Pregnancy     and     recent 

3,848 

920 

26 

529 

684 

Pneumonia,  pleurisy,  en- 
teritis, hepatitis,  peri- 
tonitis, metritis,  etc. . . 

4,001 

73 

340 

3,013 

"'824 

14,115 
3,242 

3,650 

1,881 

4 

1 

Injuries,  bruises,  etc .... 

111 

1,046 
2,315 
1,535 
1,256 
72 
2,196 

6,911 

1,150 

185 

6 

4,205 

42 

5,586 

555 

366 

6,575 
697 
591 

4,348 
2,784 

2,301 

45 

124 

'    "37 
45 

"453 
246 

40 
1 
2 

Total 

50,775 

130,139 

9,216 

1,377 

173,937 

373,993 

16,657 

939 

76 

1 

In  addition  to  the  foregoing,  there  were  tanked  the  carcasses  of 
animals  found  dead  or  in  a  dying  condition,  as  follows:  Cattle,  1,335; 
calves,  1,197;  swine,  45,266;  sheep,  5,990;  goats,  16;  total,  53,794. 

MEAT   POISONING 


Meat  poisoning  is  not  a  poisoning  as  that  term  is  ordinarily  under- 
stood, but  almost  always  an  infection;  rarely  an  intoxication.     Meat 


MEAT  619 

poisoning  is  a  further  misnomer  in  that  many  other  foods,  as  milk, 
custards,  vegetables  and  even  water  may  convey  the  responsible  bacteria, 
which  in  the  great  majority  of  instances  belong  to  the  paratyphoid 
group. 

Meat  may  be  infected  as  a  result  of  disease  in  the  animal  before 
slaughter,  or  it  may  be  contaminated  post  mortem  from  intestinal  con- 
tents, soiled  hands,  butcher's  tools,  rags,  paper,  dust,  or  other  objects. 
Chopping  obviously  favors  the  spread  of  bacteria  throughout  the  mass. 
The  inward  growth  of  bacteria  is  greatly  accelerated  if  the  meat  is  kept 
warm.  This  may  be  prevented  to  a  certain  extent,  or  at  least  delayed, 
by  drying  the  surface  and  by  refrigeration. 

Animals  suffering  during  life  from  puerperal  fever,  uterine  inflam- 
mations, naval  infection  (in  calves),  septicemia,  septic  pyemia,  diarrhea, 
and  local  suppurations  are  apt  to  furnish  meat  containing  the  para- 
typhoid bacillus  or  closely  related  bacilli.  Such  meat  has  frequently 
given  rise  to  meat  poisoning.  The  bacilli  causing  meat  poisoning  may 
also  invade  the  tissues  of  the  animal  as  a  terminal  infection,  and  thus 
become  dangerous  to  man.  The  flesh  of  a  healthy  animal  may  become 
infected  by  contamination  with  intestinal  contents,  for  the  meat-poisoning 
group  of  bacteria  are  common  inhabitants  of  the  digestive  tract  of 
many  animals. 

In  1888,  while  investigating  a  large  outbreak  of  meat  poisoning, 
Gartner  isolated  from  the  suspected  meat  and  from  the  spleen  of  a 
patient  who  died  a  bacillus  which  he  called  "'B.  enteritidis."  Ten  years 
later  Durham  in  England,  and  DeNobele  in  Belgium,  independently 
isolated  from  cases  of  meat  poisoning,  and  also  from  the  meat,  a  bacillus 
closely  allied  to  Gartner's  bacillus. 

In  1896  Acharde  and  Bensaude  isolated  from  the  urine  of  a  case  of 
apparent  enteric  fever,  and  also  from  a  purulent  arthritis,  following  a 
similar  illness,  a  bacillus  which  they  called  the  "paratyphoid  bacillus." 
In  1900-01  Schottmiiller  obtained  from  the  blood  of  patients  whose  symp- 
toms were  those  of  enteric  fever  two  bacilli  resembling  the  paratyphoid 
bacillus  of  Acharde  and  Bensaude.  These  two  organisms  were  named 
by  Brion  and  Kaiser  "paratyphosus  A"  and  "paratyphosus  B." 

The  relationship  between  these  organisms  was  not  at  once  recog- 
nized, but  it  has  been  shown  during  the  last  few  years  that  they  are 
very  closely  allied  to  each  other,  and  also  to  the  hog  cholera  bacillus, 
B.  cholera  suis  ^  of  Salmon  and  Smith,  discovered  in  1885. 

In  fact,  these  bacilli  belong  to  a  group  of  organisms  which  has  the 

^This  microorganism  is  also  known  in  England  as  B.  suipestifer.  Hog 
cholera  is  caused  by  a  filtrable  virus.  The  hog  cholera  bacillus  is  a  secondary 
invader.  Man  is  not  susceptible  to  hog  cholera.  Swine  plague  is  an  entirely 
different  disease  from  hog  cholera.  The  two  diseases  have  been  much  confused. 
Swine  plague  is  caused  by  B.  suisepticus,  which  belongs  to  the  hemorrhagic 
septicemic  group  including  B.  pestis  of  man. 


620  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

typhoid  bacillus  at  one  end  and  the  colon  bacillus  at  the  other.  The 
intermediate  forms  in  this  group  comprise  the  paratyphoid  bacilli, 
the  dysentery  bacilli,  the  hog  cholera  bacillus,  the  Bacillus  psittacosis 
(a  disease  of  parrots  communicable  to  man),  the  Bacillus  icteroides 
(once  associated  with  yellow  fever),  the  Bacillus  typhi  murium  (the 
bacillus  of  mouse  typhoid,  the  type  of  all  the  bacterial  rat  viruses),^  the 
Bacillus  enteritidis  of  Gartner  (associated  with  meat  poisoning  and 
diarrheal  diseases),  the  Bacillus  paracolon  of  Buxton,_  the  Bacillus 
pseudotuberculosis  rodentium  of  PfeifPer,  and  others.  The  organisms 
comprising  this  group  are  so  closely  related  that  it  is  often  difficult  to 
determine  where  specific  differences  begin  and  terminate.  This  group 
may  be  taken  as  a  beautiful  instance  of  missing  links,  and  a  study  of 
these  closely  related  organisms  excites  the  imagination  to  the  belief  that 
we  may  here  see  evolution  in  the  making  (see  table,  p.  621). 

Bainbridge  ^  regards  meat  poisoning  and  paratyphoid  fever  as  dis- 
tinct diseases  caused  by  different  but  closely  allied  bacilli.  He  considers 
meat  poisoning  to  be  caused  by  the  Bacillus  enteritidis  or  B.  cholera 
suis,  while  paratyphoid  fever  is  caused  by  Bacillus  paratyphosus  A  or  B. 
Bainbridge  further  regards  paratyphoid  fever  as  spread  mainly  by 
human  bacillus  carriers,  and  not  as  an  infection  contracted  from  meat, 
whereas  meat  poisoning  in  his  opinion  results  from  the  consumption  of 
food  derived  from  infected  animals  or  food  that  is  contaminated  after 
slaughter.  Bainbridge  believes  that,  as  a  rule,  the  clinical  picture  is 
quite  dissimilar,  paratyphoid  infection  resembling  typhoid  fever,  while 
meat  poisoning  usually  resembles  an  acute  gastro-enteritis.  He  admits, 
however,  that  a  reversal  of  the  clinical  picture  sometimes  occurs.  Much 
further  work  will  have  to  be  done  before  the  subject  will  be  entirely  clear. 

Fischer  divided  meat  poisoning  into  three  clinical  forms:  (1)  ty- 
phoidal,  (2)  choleraic,  (3)  gastro-enteric.  The  chief  seat  of  attack  in 
true  meat  poisoning  is  the  gastro-intestinal  canal;  the  local  irritation 
is  frequently  followed  by  a  general  bacterial  infection.  On  the  other 
hand,  sausage  poisoning  {Bacillus  botulinus)  is  a  true  intoxication  and 
expends  its  chief  attack  upon  the  nervous  system. 

Cases  of  meat  poisoning  vary  greatly  in  intensity  and  also  in  their 
clinical  picture.  The  period  of  incubation  in  the  acute  gastro-enteric 
type  is  usually  short,  rarely  over  48  hours ;  the  period  of  incubation  in 
the  cases  resembling  typhoid  fever  is  generally  from  8  to  18  days. 

The  symptoms  usually  caused  by  the  acute  form  of  gastro-enteric 
meat  poisoning  are  severe  headache  with  rigor,  speedily  followed  by 

*  In  Japan  and  elsewhere  cases  of  poisoning  with  bacterial  rat  viruses  in 
man  have  been  reported.  Most  of  these  cases  were  caused  by  preparing  rice  in 
the  same  bowl  used  for  mixing  the  rat  virus. 

^  Bainbridge,  F.  A. :  "The  Milroy  Lectures  on  Paratyphoid  Fever  and  Meat 
Poisoning."  The  Lancet,  March  16,  '1912,  Vol.  I,  No.  XI,  p.  705,  and  two  suc- 
ceeding numbers. 


MEAT 


621 


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632  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

nausea,  diarrhea,  vomiting,  and  abdominal  pain.  In  some  severe  cases 
restlessness,  extreme  thirst,  and  nervous  symptoms,  such  as  cramp,  be- 
come prominent.  Coma  may  precede  death.  Fever  is  usually  present; 
the  temperature  may  reach  103°  to  103°  F.  As  a  rule,  the  temperature 
falls  to  normal  in  from  two  to  five  days,  and  the  symptoms  subside. 
The  total  duration  of  the  illness  rarely  exceeds  a  week,  but  convalescence 
is  often  delayed  by  general  muscular  weakness  or  by  attacks  of  circulatory 
impairment.    These  are  the  cases  commonly  miscalled  ptomain  poisoning. 

Bainbridge  studied  forty  outbreaks  of  meat  poisoning  caused  by 
B.  cholera  suis  or  organisms  resembling  it.  In  twenty-eight  of  these 
the  bacillus  was  obtained  from  the  tissues,  twice  from  the  blood,  eight 
times  from  the  spleen  and  other  organs,  and  in  the  remainder  from 
the  stools.  In  twenty-one  cases  it  was  obtained  from  the  meat  which 
was  regarded  as  the  cause  of  the  outbreak.  The  illness  was  confined 
to  those  who  ate  the  meat,  though  not  every  one  who  partook  of  it 
became  ill. 

Outbreaks  caused  by  B.  enteritidis  of  Gartner,  B.  cliolera  suis,  and 
their  congeners  are  frequent.  In  Germany  at  least  360  outbreaks  have 
been  recorded  during  the  years  1898  to  1908.  Although  Germany  is 
pre-eminently  the  home  of  meat  poisoning,  outbreaks  occur  from  time 
to  time  in  most  European  countries  and  in  America.  They  appear  to 
be  more  frequent  in  countries  in  which  uncooked  or  poorly  cooked  meat 
is  eaten.  Meat  and  other  food  may  become  contaminated  after  cooking, 
or  remain  contaminated  as  the  result  of  incomplete  cooking.  Subse- 
quent growth  takes  place;  cold  meats  used  for  salads  and  otherwise  are 
often  responsible  for  outbreaks. 

Outbreaks  are  more  apt  to  occur  in  summer,  when  the  bacteria  have 
better  chances  of  multiplying  within  the  meat.  Hiibener  found  that 
of  36  outbreaks  16  occurred  during  June,  July,  and  August  and  30 
between  May  and  October.  In  another  series  of  37  epidemics  Sacquepee 
found  that  11  occurred  in  June,  July,  and  August  and  20  between  June 
and  November. 

The  meat  of  cows  and  calves  is  most  often  responsible  for  meat 
poisoning,  though  that  of  horses,  pigs,  goats  and  fowls  has  also  been 
responsible.  Dunham  says  that  no  known  case  has  come  from  mutton, 
and  that  the  pig  has  been  implicated  in  only  one  outbreak  which  has 
been  studied  bacteriologically.  This  is  of  particular  interest  to  bac- 
teriologists, on  account  of  the  similarity  between  the  hog  cholera  bacillus 
and  the  Bacillus  enteritidis. 

Gaffky,  in  1885,  described  an  outbreak  from  horse  meat.  There 
were  30  cases  with  1  fatality.  This  outbreak  was  characterized  by- 
nausea,  chills,  high  fever  and  tremor,  and  was  brought  about  by  the 
ingestion  of  raw  meat. 

An  outbreak  occurred  in  the  Insane  Hospital  in  Christiania  in  1891, 


MEAT  623 

numbering  81  cases  with  4  deaths,  characterized  by  an  acute  intestinal 
catarrh,  and  due  to  roast  veal  from  a  diseased  calf. 

In  Belgium  an  epidemic  occurred  from  eating  pork  sausages  mixed 
with  smoked  beef.  In  Germany  80  cases  occurred  as  a  result  of  eating 
meat  from  a  diseased  cow.  In  another  outbreak  86  cases  and  1  fatality 
resulted  from  the  same  cause.  In  one  outbreak  18  cases  were  due  to 
B.  enteritidis  as  a  result  of  eating  meat  from  a  cow  that  had  taken  sick 
after  calving  and  died  in  8  days.  From  1880  to  1891,  10  outbreaks 
were  reported  in  England,  due  to  pork,  1  due  to  veal,  1  to  beef,  and  1 
to  tinned  salmon.  In  one  outbreak  there  were  54  cases  and  4  deaths 
from  veal  pic. 

These  infections  are  not  only  conveyed  in  meat  and  meat  prod- 
ucts, but  also  in  other  foods.  Many  an  instance  of  so-called  ptomain 
poisoning  from  salads,  cream-puffs,  ice-cream,  etc.,  is  probably  nothing 
but  acute  infections  caused  by  one  of  the  bacteria  within  the  colon- 
typhoid  group.  This  subject  is  further  discussed  under  Paratyphoid 
Fever. 

Paratyphoid  Fever. — Paratyphoid  fever  both  clinically  and  etiologi- 
cally  is  a  first  cousin  of  typhoid  fever.  The  two  diseases  are  frequently 
indistinguishable  at  the  bedside.  It  needs  the  aid  of  the  laboratory 
to  differentiate  one  from  the  other.  Epidemiologically  paratyphoid  fever 
shows  marked  differences  from  typhoid  fever. 

Paratyphoid  is  a  world-wide  infection;  epidemic  outbreaks  occur, 
but,  as  a  rule,  are  of  limited  extent.  Paratyphoid  never  occurs  as 
great  epidemic  calamities,  such  as  have  been  frequently  observed  in 
water-borne  or  milk-borne  typhoid.  Paratyphoid  coexists  with  typhoid 
in  endemic  foci.  Thus,  in  Washington  somewhat  over  1  per  cent,  of 
all  the  cases  reported  as  typhoid  fever  were  shown,  upon  bacteriological 
examination,  to  have  been  paratyphoid.  In  India  the  proportion  is 
greater,  being  as  high  as  15  per  cent. 

The  paratyphoid  bacillus  closely  resembles  the  typhoid  bacillus  in 
its  cultural  and  morphological  characters.  They  also  vary  greatly  in 
pathogenicity  for  the  lower  animals.  Typhoid  cultures,  as  a  rule,  are 
not  very  pathogenic  for  the  lower  animals,  whereas  guinea-pigs  and 
mice  are  extraordinarily  susceptible  to  paratyphoid  cultures;  most 
strains  will  kill  guinea-pigs  when  1/50  to  1/100  of  a  loop  is  injected 
into  the  peritoneal  cavity.  Eabbits  are  also  susceptible;  birds  are 
entirely  refractory ;  cattle,  dogs,  cats,  hogs,  sheep,  show  a  high  degree  of 
resistance  to  paratyphoid  cultures. 

A  fundamental  point  of  difference  between  the  paratyphoid  and  the 
typhoid  organisms  is  that  they  each  have  specific  agglutinating  prop- 
erties. In  any  critical  case  this  difference  is  the  most  important  dis- 
tinguishing feature.  Care  must  be  taken,  in  using  agglutinins,  in  dif- 
ferentiating these   closely   allied   species,   to   guard   against   confusion 


624  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

through  group  agglutinins,  and  also  to  keep  the  proagglutinoid  zone 
in  mind. 

The  paratyphoid  bacillus  is  a  small  rod  with  rounded  ends  and 
peritrichal  flagellae  resembling  the  typhoid  bacillus,  except  that  it  is 
more  actively  motile.  It  stains  readily  with  anilin  dyes,  is  decolorized 
by  Gram's  solution,  does  not  liquefy  gelatin,  has  no  spore,  and  is  a 
facultative  aerobe ;  it  clouds  bouillon  uniformly,  and  does  not  produce  in- 
dol.  Upon  Endo's  medium  the  paratyphoid  colonies  are  pale,  moist, 
translucent,  with  a  bluish  cast,  quite  similar  to  typhoid  colonies. 

The  paratyphoid  bacillus  is  divided  into  several  subclasses.  These 
classes  vary  with  the  classifier.  Schottmiiller  in  1902  divided  them  into 
paratyphoid  A  and  paratyphoid  B.  In  the  same  year  Buxton  proposed 
that  paratyphoid  organisms  be  confined  to  those  producing  a  disease 
resembling  typhoid,  while  paracolon  be  used  to  designate  those  organ- 
isms producing  gastro-intestinal  disturbances.  We  now  hear  little  of 
the  paracolon  group.  Seiffert,  who  studied  the  question  in  Ehrlich's 
laboratory,  considers  two  groups,  viz.,  paratyphoid  A,  those  producing 
permanent  acidity  in  litmus  whey,  and  paratyphoid  B,  those  producing 
acidity  terminating  in  alkalinity  in  litmus  whey.  Group  B  also  pro- 
duces characteristic  lesions  when  injected  into  the  muscles  of  pigeons. 
The  group  known  as  paratyphoid  B  is  much  more  common  and  wide- 
spread than  type  A.  It  is  interesting  to  observe  that  the  agglutinins 
have  a  closer  relationship  between  paratyphoid  B  and  typhoid  than 
between  paratyphoid  A  and  typhoid,  although  type  B  seems  farther 
removed. 

The  paratyphoid  bacillus  may  be  found  in  the  blood  and  internal 
organs,  also  in  the  feces;  seldom  in  the  urine.  It  produces  a  continued 
fever  in  man  closely  resembling  typhoid  fever.  As  a  rule,  paratyphoid 
is  milder  than  typhoid.  Lentz  ^  gives  a  mortality  of  3.3  per  cent., 
against  typhoid,  which  is  about  9  per  cent.  Paratyphoid  infections 
frequently  manifest  themselves  as  an  acute  gastro-enteritis,  having  a 
sudden  onset  with  vomiting,  chill,  and  diarrhea  and  a  sharp  rise  of 
temperature.  Between  these  acute  cases  and  the  typhoid  type  there 
are  all  grades  of  severity  and  several  clinical  varieties. 

Paratyphoid  fever  may  be  complicated  with  hemorrhages  from  the 
bowels,  bronchitis,  and  pneumonic  processes,  just  as  in  typhoid  fever; 
relapses  are  rare.  It  is  not  definitely  known  how  much  of  an  immunity 
is  conferred  by  one  attack,  but  it  is  known  that  paratyphoid  does  not 
protect  against  typhoid,  nor  does  typhoid  protect  against  paratyphoid. 

The  paratyphoid  bacillus,  although  it  contains  no  spore,  is  claimed 
to  have  a  higher  degree  of  resistance  to  heat  than  the  typlioid  bacillus. 
Thus,  Fischer  ^  found  that  an  exposure  to  70°  C.  for  10  to  20  minutes 

^  CentralUatt  f.  Bakt.,  Referate.  Bd.  XXXVIII. 

"Testschr.  f.  K  Koch,"  Jena,   1903, 


MEAT  625 

did  not  destroy  this  microorganism.  This  unusual  resistance  is  impor- 
tant^ in  view  of  the  fact  that  the  bacillus  may  be  conveyed  in  meat  and 
other  foods.  As  a  rule,  the  inside  of  a  large  piece  of  meat  or  a  bulky 
sausage  does  not  reach  70°  C.  during  the  process  of  cooking. 

Paratyphoid  outbreaks  have  recently  also  been  reported  as  a  result 
of  infection  in  milk  and  in  water.  The  so-called  toxin  produced  by  the 
paratyphoid  bacillus  is  not  destroyed  by  heat.  There  is  no  satisfactory 
evidence  that  this  "toxin"  is  poisonous  by  the  mouth. 

The  virus  enters  the  body  through  the  mouth  and  is  discharged  in 
the  feces.  The  intestinal  tract  of  man  must  be  regarded  as  the  great 
reservoir  for  paratyphoid  infection,  just  as  it  is  the  main  source  of 
typhoid.  The  paratyphoid  bacillus  does  not,  as  a  rule,  multiply  in 
nature,  except  in  meat,  and  perhaps  other  foodstuffs. 

Paratyphoid  fever  is  by  no  means  always  contracted  from  food, 
but  may  be  transmitted  directly  from  man  to  man.^  When  this  takes 
place  the  mode  of  transmission  is  similar  to  that  of  typhoid  fever. 

Paratyphoid  is  often  spread  through  carriers. 

Prevention. — The  prevention  of  paratyphoid  fever  corresponds  in 
all  essential  particulars  to  the  prevention  of  typhoid  fever,  and  takes 
into  consideration  water,  milk,  meat  and  other  foods;  contacts;  flies; 
fomites;  carriers,  etc. 

Meat  inspection  affords  but  little  safeguard  against  the  meat  poison- 
ing group  of  bacteria,  for  the  reason  that  these  microorganisms  may 
pervade  the  meat  without  in  the  least  changing  its  appearance,  color, 
flavor,  or  odor.  Their  presence  may  only  be  detected  by  bacteriological 
examination.  In  this  respect  paratyphoid  and  its  congeners  in  meat 
correspond  strikingly  to  typhoid  and  other  infections  in  milk.  Animals, 
however,  suffering  with  septicemic  infections,  puerperal  fever,  metritis, 
diarrhea,  and  serious  inflammations  of  any  kind  should  be  condemned 
by  the  meat  inspector  on  account  of  the  danger  of  conveying  infections  of 
the  kind  in  question.  Scrupulous  cleanliness  must  be  observed  in 
slaughter  houses,  butcher  shops,  and  the  home.  The  butcher's  hands 
and  implements  require  cleanliness  of  a  surgical  order ;  housewives  should 
refuse  to  patronize  butcher  shops  that  are  not  carefully  screened,  that  do 
not  have  sufficient  refrigeration,  and  that  are  not  tidy  and  cleanly 
throughout.  Greater  care  should  also  be  exercised  with  meat  in  trans- 
portation, whether  upon  the  railroad  or  the  delivery  wagon.  Cleanliness 
and  effective  refrigeration  in  the  household  and  in  restaurants  is  essential. 

The  paratyphoid  bacillus  does  not  necessarily  exist  in  the  tissues 
of  the  animal  at  the  time  of  its  death,  but  the  meat  may  become  in- 
fected while  it  is  butchered  or  during  any  stage  in  its  after-care.  The 
paratyphoid  bacillus  deposited  upon  a  roast,  steak,  or  a  carcass  will 
grow  readily  and  rapidly  throughout  the  mass,  especially  if  kept  warm. 

*  Gartner,  v.  Ermengen,  Fischer,  Bainbridge. 


626  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

It  is  easy  to  conceive  how  meat  may  thus  become  infected  through 
the  contamination  of  dirty  hands,  butchers'  implements,  soiled  meat 
blocks,  unclean  cloths,  etc.  It  is  not  unknown  that  carcasses  or  cut 
portions  may  fall  upon  the  floor  or  in  other  ways  be  carelessly  handled. 
This  and  other,  infections  may  also  be  carried  to  meat  through  flies, 
dust,  and  other  well-known  means  of  bacterial  convection.  Meat  may 
be  infected  in  the  slaughter  house,  in  the  butcher  shop,  during  trans- 
portation, or  in  the  household.  In  fact,  meat  may  become  infected 
in  very  much  the  same  ways  that  milk  becomes  infected,  and  the  same 
care  and  cleanliness  are  called  for  in  each  case. 

Meat  that  is  hashed,  as  in  Hamburg  steak,  or  prepared  in  a  sau- 
sage, is  especially  liable  to  infection  on  account  of  the  additional  hand- 
ling and  because  the  bacteria  pervade  the  minced  articles  more  readily 
than  they  do  the  solid  chunks.  The  paratyphoid  bacillus  has  been 
isolated  from  sausages. 

Thorough  cooking  destroys  the  infection  and  eliminates  the  danger 
of  meat  poisoning  due  to  bacteria  belonging  to  the  group  under  con- 
sideration. It  must  not  be  forgotten,  however,  that  meat  after  it  is 
cooked  and  allowed  to  stand  may  become  infected,  and,  further,  that 
the  cooking  must  be  thorough. 

Other  Infections. — Meat  heavily  laden  with  B.  proteus,  B.  coli,  B. 
pyocyaneus  or  with  streptococci  or  even  staphylococci  may'  be  injuri- 
ous when  consumed.  The  relationship  however  between  these  micro- 
organisms and  the  symptoms  they  may  produce  is  not  clear. 

Botulism  or  Sausage  Poisoning.— ^Botulism  is  a  specific  intoxication 
produced  by  a  saprophyte.  The  symptoms  are  caused  by  a  poison  that 
is  generated  by  the  Bacillus  botulinus  outside  of  the  body.  The  bacillus 
itself  is  harmless  and  does  not  grow  and  multiply  within  the  body.  In 
this  respect  botulism  is  a  sharp  contrast  to  meat  poisoning  produced  by 
the  paratyphoid  and  related  bacilli. 

The  Bacillus  botulinus  may  grow  and  produce  its  toxin  in  sausage, 
meat,  or  fish,  and  occasionally  in  vegetables;  in  fact,  it  may  develop 
upon  protein  media  of  all  kinds.  It  requires  time  for  the  growth  and 
development  of  the  toxin;  fresh  foodstuffs,  therefore,  are  not  danger- 
ous so  far  as  botulism  is  concerned.  Meat,  sausage,  or  fish  that  contains 
the  botulism  toxin  may  or  may  not  be  altered  in  color,  taste,  or  odor; 
sometimes  the  indications  of  putrefactive  and  fermentative  changes  are 
evident.  But  the  presence  or  absence  of  such  alterations  are  not  in 
themselves  an  index  of  the  presence  or  absence  of  the  botulismus  toxin. 

Botulism  is  more  common  in  Europe  than  in  this  country.  The  first 
outbreak,  studied  by  v.  Ermengen,  occurred  in  Ellezelles,  Belgium,  in 
1895.  Fifty  persons  were  affected,  of  whom  three  died.  The  particular 
ham  which  was  responsible  in  this  case  was  preserved  in  a  weak  brine  at 
the  bottom  of  a  cask  under  anaerobic  conditions.     Another  ham  in  the 


MEAT  627 

same  cask  above  the  brine  had  a  different  bacterial  flora  and  was  not 
poisonous. 

Sausages  are  the  most  frequent  source  of  botulism.  The  sausages 
readily  become  infected  and  present  ideal  anaerobic  conditions  for  the 
growth  of  the  organism,  especially  as  they  are  rarely  refrigerated  and 
frequently  contain  old  and  contaminated  scraps.  The  disease  is,  there- 
fore, frequently  called  sausage  poisoning  from  hotulus,  a  sausage.  Cer- 
tain sausages,  as,  for  example,  the  blood  sausage  and  the  liver  sausage 
prepared  in  Wiirttemberg  and  Baden,  are  especially  apt  to  be  infected. 
Salt  fish,  smoked  ham,  preserved  meat,  venison,  old  roasts,  have  produced 
the  intoxication.  The  bacillus  may  even  grow  in  nitrogenous  vegetables ; 
thus,  spoiled  beans  were  responsible  for  an  outbreak  in  Hessen. 

Symptoms. — After  a  period  of  incubation  of  about  20  to  24  hours 
there  are  nausea,  gastric  pains,  vomiting,  visual  disturbances,  such  as 
fogging  of  the  eyes,  sometimes  amounting  almost  to  blindness,  dilatation 
of  the  pupils,  and  loss  of  reaction  to  light,  ptosis  of  both  lids,  and  a 
peculiar  stony  stare.  There  are  burning  thirst  and  difficulty  in  swal- 
lowing, the  mucous  membrane  of  the  respiratory  tract  is  strongly  red- 
dened and  covered  with  a  thick  viscid  secretion,  which  causes  severe 
attacks  of  coughing  and  even  suffocation.  There  is  extreme  muscular 
weakness;  the  respiration  and  circulation  remain  normal;  there  is  no 
fever;  death  may  ensue;  recovery  is  slow. 

The  Bacillus  hotulinus  discovered  by  v.  Ermengen  in  1899  is  a  large, 
slightly  motile  rod,  4  to  6  ju  long,  .9  to  1.2  p.  thick.  It  has  slightly 
rounded  ends;  4  to  8  flagellae,  generally  single;  rarely  occurs  in  fila- 
ments ;  has  a  large  polar  spore ;  stains  readily,  and  and  is  Gram-positive. 

The  bacillus  grows  best  between  20°  and  30°  C,  but  does  not  thrive 
above  35°  C,  hence  does  not  multiply  in  the  body.  It  is  a  strict  anerobe, 
and  requires  a  distinctly  alkaline  medium.  Its  growth  is  favored  by 
the  addition  of  2  per  cent,  grape  sugar;  gelatin  is  not  liquefied,  but 
active  gas  formation  takes  place  similar  to  cultures  of  malignant  edema 
and  other  anerobes.  It  does  not  alter  milk.  All  the  cultures  emit  the 
odor  of  butyric  acid.  The  spores  are  killed  at  85°  C.  for  15  minutes  or 
80°  C.  in  one  hour. 

The  Bacillus  hotulinus  has  been  isolated  from  various  foodstuffs. 
Kempner  obtained  it  from  the  feces  and  Landtman  isolated  it  from 
poisonous  canned  beans.  In  habitat  and  biology  it  resembles  tetanus 
spores,  and  it  is,  therefore,  supposed  to  exist  in  the  soil,  but  attempts  to 
find  it  in  the  soil  have  resulted  negatively.  It  is  perhaps  not  widely  dis- 
tributed in  nature. 

BoTULiSMius  Toxin. — The  bacillus  produces  a  soluble,  true  toxin  ^ 
comparable  in  all  respects  to  the  poisons  produced  in  cultures  of  diph- 
theria or  tetanus.    The  poison,  however,  is  produced  outside  of  the  body, 

*  For  definition  of  a  true  toxin  see  page  414  et  seq. 


628  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

not  in  it.  There  is  no  toxin  production  and  little  growth  at  l>ody  temper- 
ature. The  bacillus  is  a  true  saprophyte ;  thus,  the  Bacillus  boiulinus 
occupies  a  position  of  its  own,  being  pathogenic  only  by  virtue  of  the 
poison  formed  on  dead  nitrogenous  substances.  It,  therefore,  is  the  type 
of  a  toxicogenic  organism,  a  term  proposed  by  v.  Ermengen.  The 
Bacillus  hotulinus,  however,  is  the  only  definitely  known  example  of  this 
category. 

There  are  doubtless  other  microorganisms  that  produce  substances 
in  dead  organic  matter  which  are  poisonous  when  partaken  of  by  man. 
Of  these  the  Bacillus  proteus  vulgaris  and  the  Bacillus  coU  communis 
(Bacterium  coli)  are  believed  to  play  such  a  role.  Instances  of  poison- 
ing with  these  organisms  have  been  studied  by  numerous  investigators, 
but  their  "toxins"  and  their  action  are  less  well  understood  than  in  the 
case  of  botulismus. 

The  botulismus  toxin  is  the  only  one  of  the  true  toxins  that  is  poison- 
ous when  taken  by  the  mouth.  It  is  thus  pathogenic  for  guinea-pigs, 
mice,  and  monkeys,  as  well  as  for  man.  Ona  or  two  drops  of  a  culture 
placed  upon  a  piece  of  bread  causes  death  in  a  few  days.  Toxins  of 
diphtheria  and  tetanus  are  not  poisonous  when  taken  by  the  mouth. 
Cats  and  rabbits,  however,  withstand  large  doses  of  botulismus  toxin  by 
the  mouth,  but  are  very  susceptible  to  subcutaneous  or  intravenous  injec- 
tion. The  botulismus  toxin  is  readily  killed  by  heat,  and  is  very  suscep- 
tible to  acids  and  alkalis;  it  also  deteriorates  in  sunlight. 

A  true  antitoxin  may  be  obtained  by  injecting  increasing  amounts 
into  susceptible  animals.  Kempner  first  obtained  the  antitoxin  in  goats. 
Much  work  has  since  been  done  upon  this  toxin  and  antitoxin  by  Mad- 
sen  and  others.  The  botulismus  antitoxin  has  both  protective  and 
curative  virtues  in  man  as  well  as  in  experimental  animals,  even  when 
given  24  hours  after  the  ingestion  of  the  poison.  It  has  recently 
been  prepared  for  distribution  at  the  Institute  for  Infectious  Diseases 
at  Berlin. 

Peevention. — Prevention  of  botulism  consists  in  greater  care  and 
cleanliness  in  the  handling  and  preservation  of  nitrogenous  foodstuffs. 
The  spores  may  remain  on  sausage  casings  and  afterwards  germinate  in 
the  sausage  and  thus  produce  toxin.  There  is  no  danger  of  this  poison 
in  fresh  foods,  or  in  foods  preserved  a  long  time,  if  properly  sterilized 
in  the  can  or  properly  refrigerated.  The  chief  danger  is  from  sausages 
eaten  without  cooking.  The  heat  destroys  the  toxin,  but  it  must  be  suffi- 
cient and  penetrate  throughout  the  mass;  also  the  cooking  must  be 
recent,  for  the  bacillus  grows  well  in  cooked  foods.  When  obtainable 
the  antitoxin  may  be  used  as  a  preventive  in  cases  where  a  number  of 
persons  are  showing  symptoms  of  poisoning  from  having  partaken  of  the 
same  carcass  or  sausage  or  other  suspected  food. 


MEAT  629 


ANIMAL  PARASITES 

Trichinosis. — Trichinella  spiralis,  formerly  Trichina  spiralis,  com- 
monly known  as  trichina,  is  a  round  worm  which  passes  its  entire  life 
cycle  in  man,  rat,  or  hog.  Many  other  animals,  such  as  mice,  foxes, 
guinea-pigs,  rabbits,  cats,  dogs,  etc.,  are  susceptible.  This  parasite  dif- 
fers from  many  other  animal  parasites  in  affecting  several  genera  and 
in  passing  its  entire  life  cycle  in  each  host.  Trichinosis  is  rare  in  ani- 
mals which  do  not  eat  meat. 

Trichiniasis  (usually  called  trichinosis)  is  not  a  mere  medical  curi- 
osity. It  is  a  common  and  impor- 
tant  disease,  readily  preventable. 
The  average  mortality  is  about  half 
that  of  typhoid  fever,  in  some  epi- 
demics, however,  rising  to  16  or  even 
30  per  cent.,  as  in  the  Hedersleben 
epidemic  ^  in  1865.  The  parasites 
are  found  in  from  0.5  to  2  per  cent, 
of  all  necropsy  subjects.^  About  1 
to  2  per  cent,  of  American  swine  and 

a  larger  per  cent,  of  American  rats 

■    P     I    -,  Fig.  76. — Trichinella  Spiralis.     Entire 

are  mtected.  Life  cycle  in  Each  Host. 

The  larvae  are  imbedded  in  the 
muscles.  When  the  trichinous  meat  is  taken  the  capsules  are  dissolved 
in  the  stomach,  the  larvae  set  free;  the  freed  larvae  enter  the  intestine, 
where  they  find  conditions  favorable,  and  where  in  about  two  days  they 
grow  into  the  full  mature  worm.  The  female  parasite  produces  upward 
of  five  hundred  young,  and  it  is  these  embryos  that  pierce  the  bowel  and 
penetrate  into  the  tissues.  They  get  into  the  blood  stream-  and  are  thus 
distributed  to  the  muscles.  It  takes  about  7  to  9  days  to  accomplish 
these  changes ;  that  is,  for  the  larvae  in  the  muscles  to  develop  from  the 
brood  of  embryos  in  the  intestine.  The  adult  worms  usually  disappear 
from  the  intestines  in  5  or  6  weeks,  or  even  sooner  if  the  patient  has 
diarrhea.  The  encysted  larvae  in  the  muscles  remain  7  or  8  months 
when  they  begin  to  degenerate,  commonly  become  calcified  and  the  larvae 
finally  die. 

The  normal  or  common  host  of  Trichinella  spiralis  may  be  regarded 

as  the  rat,  which  gets  infected  about  slaughter  houses  and  butcher  shops. 

Hogs  get  the  disease  by  eating  rats,  through  feces,  or  directly  from 

infected  offal.     Man  receives  the  infection  by  eating  trichinous  pork 

(occasionally  dog,  cat,  or  bear  meat).     The  country  slaughter  houses, 

^  Cited  by  Straubli,  Trichinosis,  Wiesbaden,  1909,  p.   16. 

"  Williams  found  evidence  of  jnfectiQn  in  5,3  per  cent,  of  505  consecutive 
autopsies  in  Buffalo,  N.  Y. 


630  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

where  hogs  are  fed  on  human  feces  and  the  offal  of  slaughtered  animals 
and  where  rats  abound,  are  the  most  important  factors  in  the  propaga- 
tion of  the  infection. 

Not  all  persons  who  eat  trichinous  flesh  have  the  disease.  A  limited 
number  of  the  embryos  do  not  cause  noticeable  symptoms.  The  number 
of  encysted  larvae  that  may  be  present  in  severe  infestation  is  very  large. 
As  many  as  1,200  have  been  counted  in  a  piece  of  muscle  weighing  1 
gram,  which  would  make  about  500,000  in  a  pound.  The  number  of 
encysted  larvae  present  in  the  bodies  of  persons  who  have  died  from 
trichinosis  has  been  estimated,  in  various  cases,  at  from  5,000,000  to 
100,000,000.  In  man  the  disease  is  well  characterized  in  two  stages : 
(1)  gastro-intestinal,  (2)  general  infection.  The  symptoms  of  the  sec- 
ond stage  are  fever,^  intense  pain  in  the  muscles  caused  by  the  migration 
of  the  parasites,  edema,  and  leukocytosis.  The  count  of  the  white  cells 
may  reach  30,000  with  distinct  eosinophilia. 

The  recognition  of  trichinosis  as  a  distinct  infection  is  recent  (1860). 
The  parasite  was  named  by  Eichard  Owen  and  was  long  regarded  as 
harmless  and  as  a  curiosity.  The  infection  was  mistaken  for  typhoid 
fever,  rheumatism,  acute  miliary  tuberculosis,  and  other  diseases  of  com- 
mon occurrence.  The  particular  case  which  finally  revealed  the  parasite 
as  being  capable  of  harm  was  that  of  a  young  woman  admitted  to  the 
hospital  at  Dresden  suffering  from  a  disease  diagnosed  as  typhoid  fever. 
The  patient  had  agonizing  pains  in  the  muscles,  and  the  autopisy  revealed 
the  parasite  imbedded  in  vast  numbers  in  the  muscular  fibers.  An 
investigation  led  to  the  examination  of  some  pork  of  which  she  had 
eaten  four  days  before  the  first  symptoms  appeared,  and  showed  the 
presence  of  the  same  parasite.  Since  then  many  local  outbreaks  have 
been  described,  more  particularly  in  Germany,  where  the  custom  prevails 
of  eating  raw  or  underdone  pork,  especially  in  sausage. 

To  show  the  great  prevalence  of  the  disease,  the  microscopists  of 
the  United  States  Department  of  Agriculture  found  the  parasite  in 
41,659  of  2,227,740  hogs  examined.  From  1  to  2  per  cent,  of  the  hogs  in 
this  country  are  trichinous.  The  disease  in  man  is  probably  more  prev- 
alent than  the  figures  of  the  clinicians  indicate.  Careful  search  at 
autopsy  showed  that  many  persons  have  been  infected  but  have  recov- 
ered. Thus,  Williams  ^  of  Buffalo  examined  505  unselected  cadavers 
and  showed  old  encapsulations  and  calcifications  in  37,  or  5.34  per  cent. 
Osier  states  that  about  one-half  to  two  per  cent,  of  all  bodies  at  autopsy 
contain  trichinae. 

Prevention. — The  disease  is  practically  never  recognized  in  swine 
during  life.    The  protection  rendered  by  the  inspection  of  meat  is  quite 

*  Trichinella  spiralis  is  the  only  metazoie  parasite  that,  infecting  man, 
causes  fever  with  constancy. 

'^Journal  Medical  Research,  July,  1901,  VI,  No.  1,  p.  64. 


MEAT  631 

unsatisfactory.  This  inspection  consists  in  compressing  small  fragmjcnts 
of  the  muscle  (diaphragm,  tongue,  etc.)  between  two  glass  plates,  which 
are  then  examined  with  a  low  power  of  the  microscope  for  the  encysted 
larvae.  That  this  examination  is  not  an  entirely  satisfactory  safeguard, 
even  in  cases  where  it  is  done  with  care  and  precision,  is  shown  by  the 
fact  that  in  Germany,  for  example,  the  disease  is  still  very  common. 
Of  the  6,329  cases  of  trichinosis  occurring  in  Germany  between  1881  and 
1898,  over  33  per  cent.  (2,042  cases)  were  traced  by  Stiles  to  meat  which 
had  been  inspected  and  passed  as  free  from  trichinae.  The  microscopic 
inspection  of  every  carcass  for  trichina  is  expensive  and  open  to  several 
practical  sources  of  error.  It,  therefore,  gives  a  false  sense  of  security 
and  is  impractical  in  country  slaughter  houses. 

Our  federal  meat  inspection  regulations  no  longer  require  a  micro- 
scopic examination  of  pork  for  trichina.  Until  recently  all  the  pork 
dressed  for  export  was  examined  by  the  microscopic  method,  but  this 
has  also  been  discontinued. 

The  U.  S.  Bureau  of  Animal  Industry  issues  the  following  warning: 

"No  method  of  inspection  has  yet  been  devised  by  which  the  pres- 
ence or  absence  of  trichinae  in  pork  can  be  determined  with  certainty, 
and  the  Government  meat  inspection  does  not  include  inspection  for  this 
parasite.  All  persons  are  accordingly  warned  not  to  eat  pork,  or  sausage 
containing  pork,  whether  it  has  been  officially  inspected  or  not,  until 
after  it  has  been  properly  cooked. 

"A  temperature  of  about  160°  F.  kills  the  parasite,  therefore  pork 
when  properly  cooked  may  be  eaten  without  danger  of  infection.  Fresh 
pork  should  be  cooked  until  it  becomes  white  and  is  no  longer  red  in 
color  in  all  portions  of  the  piece,  at  the  center  as  well  as  near  the  surface. 
Dry-salt  pork,  pickled  pork,  and  smoked  pork  previously  salted  or 
pickled,  providing  the  curing  is  thorough,  are  practically  safe  so  far 
as  trichinosis  is  concerned,  but  as  the  thoroughness  of  the  curing  is  not 
always  certain,  such  meat  should  also  be  cooked  before  it  is  eaten." 

The  trichinae  are  not  particularly  resistant,  being  killed  at  155°  F. 
if  they  are  not  encapsulated,  otherwise  at  158°  to  160°  F. ;  that  is,  they 
have  about  the  same  resistance  as  non-sporulating  bacteria. 

Trichina  larvae  die  in  20  days  at  a  temperature  not  higher  than 
5°  F.  Eansom  ^  disproved  the  notion  formerly  held  that  the  larvae 
of  Trichinella  spiralis  are  very  resistant  to  cold.  He  recommends  that 
meat  should  be  refrigerated  at  a  temperature  not  higher  than  5°  F.  for 
not  less  than  20  days,  a  period  which  allows  a  probable  margin  of 
safety  of  10  days.  Whether  temperatures  higher  than  5°  F.  may  be 
safely  employed  by  lengthening  the  period  of  refrigeration,  remains 
to  be  determined.     It  is,  therefore,  evident  that  refrigeration  and  time 

^Science,  New  York,  January  30,  1914.  Vol.  XXXTX,  p.  181,  and  The  Journal 
of  Agricultural  Research,  Vol.  V,  No.  18,  January  31,  1916. 


632  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

are  better  safeguards  than  microscopic  examination.  The  combination 
of  refrigeration  and  thorough  cooking  would  protect  man  against 
trichinosis. 

The  rat  and  the  hog  should  be  regarded  as  the  common  reservoir  of 
trichinae;  a  persistent  warfare  should  be  made  against  rats  in  slaughter 
houses,  butcher  shops,  markets,  and  places  where  hogs  are  kept  (see  page 
267). — Human  feces  and  contaminated  offal  must  not  be  fed  to  hogs. 

The  Pork  or  Measly  Tapeworm  {Taenia  Solium). — Taenia  solium 
passes  the  larval  stage  of  its  life  history  in  the  flesh  of  pork.  These 
encysted  larvae  are  known  as  bladder  worms  or  Cysticercus  cellulosae; 

they      are      commonly 

Man    (Tenia  Solium)  ,,    t  ,  , 

called  pork  measles. 
Man  eats  these  encysted 
larvae  which  develop 
into  adult  tapeworms 
in  the  intestinal  tract. 
Infection  with  this 
tapeworm  may  be  par- 
ticularly dangerous,  be- 
,W(w  cause      the      cysticerci 

(C.,tJctL/./o.a.)  ^Cysticercus  Ce,Mosae)  h^,,       ^he       peculiarity 

Fig.  77. — Taenia  Solium,  the  Pokk  or  Measly  Tape-  ^         -^ 

WORM.     Note  that  man  may  infect  himself.  man    as    well    as    in    the 

hog.  When  the  cysti- 
cerci develop  in  important  parts,  such  as  the  eye,  brain,  etc.,  death  or 
serious  consequences  may  ensue.  The  infection  with  this  particular  tape- 
worm is  fortunately  rare  in  the  United  States  and  Canada,  but  is  more 
frequently  met  with  in  the  old  world.  The  adult  tapeworm  occurs  only 
in  man;  the  larva  is  found  especially  in  hogs  and  occasionally  in  sheep 
and  dogs.  This  parasite  is  smaller  than  the  beef  tapeworm.  The  head  is 
armed  with  a  double  row  of  hooks,  with  which  it  maintains  its  hold  to 
the  mucous  membrane.  Each  link  contains  a  uterus  with  lateral 
branches,  and  the  genital  pore  is  marginal  and  irregularly  alternate. 

The  source  of  infection  in  man  is  practically  always  undercooked 
or  raw  pork.  Occasionally  the  infection  is  contracted  from  another 
person  through  the  eggs  in  the  feces.  Hogs  become  infected  from  eat- 
ing human  feces  containing  the  eggs,  or  from  food  and  drink  contami- 
nated with  them.  To  build  a  privy  over  the  pig  pen,  as  one  sometimes 
sees  in  the  country,  means  the  formation  of  an  endless  chain  in  the 
biology  of  this  worm. 

Taenia  solium  produces  less  anemia  than  the  fish  tapeworm  (Diho- 
thriocephalus  latus),  but  may  be  dangerous  because  of  cysticercus  forma- 
tion in  man.  This  is  the  only  tapeworm  in  which  this  occurs.  A  person 
infected  with  Taenia  solium  may  reinfect  himself  through  dirty  finger 


MEAT  633 

nails,  unwashed  hands,  or  other  uncleanly  habits,  and  it  is  also  compara- 
tively easy  to  infect  others  through  the  feces. 

In  prevention  one  must  first  consider  the  disposal  of  feces.  Hogs 
heavily  infected  should  be  destroyed ;  those  having  a  light  infection  may 
be  thoroughly  cooked  and  the  meat  eaten.  Cold  storage  is  not  quite  so 
effective  in  destroying  the  larvae  of  Taenia  solium  as  it  is  for  Taenia  sagi- 
nata,  for  the  former  have  been  found  alive  after  29  days,  whereas  the 
latter  die  after  21  days. 

Taenia  Saginata. — Taenia  saginata,  also  called  Medio canellata,  occurs 
only  in  cattle  and  man.  This  tapeworm  is  rather  common  in  our  coun- 
try, but  is  not  dangerous,  like  Taenia  solium,  though  at  times  it  produces 
a  certain  degree  of  anemia  and  other  symptoms.  It  is  often  difficult 
to  expel,  despite  the  fact  that  it  has  no  „      ,-r      „   .       ^ 

ir     ^  ir  ...  "»'"'    {Tenia  Sagmattd) 

hooks.  In  geographical  distribution  it  is 
cosmopolitan.  The  adult  worm  occurs  in 
man;  the  larva  is  found  imbedded  in  beef 
and  is  known  as  the  Cysticercus  bovis. 
The  uterus  has  15  to  35  slender  dichotomous 
branches  on  each  side.  The  genital  pore  is 
marginal  and  irregularly  alternate. 

Eansom  ^  concludes  that  if  measly  beef 
carcasses  are  exposed  6  days  to  a  temper- 

,  .  Cattle 

ature  not  exceeding  15°   F.   the  parasites  {Cystieercus  Bouts) 

die.  Fig.  78. — Beef    Tapewokm. 

Man   becomes   infected   by   eating   raw 
or  underbone  beef.  ■  The  tongue  and  the  muscles  of  mastication  most 
frequently  contain  the  larvae.     Cattle  become  infected  through  the  eggs 
passed  in  human  feces,  which  contaminate  their  food  or  water. 

Prevention. — The  prevention  depends  first  upon  proper  disposal 
of  human  excrement  and  an  efficient  system  of  meat  inspection.  The 
cysticerci  die  in  three  weeks  after  killing,  hence  meat  that  has  been  pre- 
served 21  days  may  be  regarded  as  safe.  Proper  cooking  and  thorough 
salting  also  kill  the  larvae  of  this  tapeworm. 

Echinococcus  Disease.^ — The  larvae  of  a  cestode.  Taenia  echinococcus, 
frequently  infests  man.  The  larvae  are  hydatids  of  a  minute  tapeworm 
of  the  dog.  The  adult  worm  in  the  intestinal  tract  of  the  dog  is  not 
more  than  four  or  live  millimeters  long  and  consists  of  three  or  four 
segments  of  which  the  terminal  one  alone  is  mature.  The  head  is  small 
and  provided  with  four  sucking  disks,  and  a  rostellum  with  a  double  row 
of  booklets.  The  terminal  or  mature  segment  contains  about  5,000  eggs. 
The  eggs  are  passed  in  the  feces  and  then  infest  various  animals,  particu- 

^Jour.  of  Parasitology,  Sept.   1,  1914,  No.  I. 

•Echinococcus  disease  is  not  contracted  by  man  from  meat — but  is  con- 
veniently considered  in  this  chapter  with  the  other  tapeworms. 


634,  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

larly  the  hog  and  ox,  more  rarely  the  horse  and  sheep.  The  egg  hatches 
in  the  digestive  tube,  liberating  an  embryo  which  pierces  the  mucosa 
and  lodges  in  the  various  tissues  and  organs  of  the  body,  where  it 
develops  into  the  larval  or  cystic  stage  (hydatids). 

The  disease  prevails  especially  in  those  countries  where  man  is 
brought  in  close  contact  with  the  dog,  but  more  especially  when,  as  in 
Australia,  the  dogs  are  used  to  herd  sheep.  The  dog  gets  the  larvae 
from  the  sheep.  In  the  dog  the  tapeworm  reaches  maturity  in  the 
intestinal  canal,  and  the  eggs  are  passed  in  the  feces  to  infect  sheep, 
man,  and  other  animals.  In  this  country  Taenia  echinococcus  is  rarely 
found  in  the  dog.  The  larva  imbeds  itself  in  the  tissues  and  there 
develops  a  cyst — the  hydatid  cyst.  This  may  occur  in  the  liver,  lungs, 
abdominal  organs,  nervous  system,  in  fact  in  almost  any  part  of  the  body. 
The  cysts  grow  in  size  as  the  larvae  multiply,  forming  daughter  cysts  and 
grand-daughter  cysts. 

The  first  essential  in  prophylaxis  is  to  protect  the  dog  against  infec- 
tion. This  resolves  itself  into  a  good  system  of  meat  inspection,  sani- 
tary slaughter  houses,  proper  disposal  of  offal,  and  the  keeping  of  dogs 
away  from  slaughter  houses,  butcher  shops,  rendering  plants,  and  the 
like.  If  offal  is  used  as  food  for  dogs,  hogs  and  other  animals  it  should 
first  be  thoroughly  boiled. 

The  eggs  of  the  worm  reach  the  mouth  of  man  directly  and  indirectly 
from  the  dog  in  various  ways — through  drinking  water,  through  food 
soiled  with  dog  feces,  through  dirty  hands.  Dogs  lick  their  anal  region 
and  also  lick  fecal  matter,  and  hence  may  directly  transmit  the  eggs 
to  man  through  licking  and  fondling.  In  an  infested  region,  drinking 
water  should  be  boiled ;  likewise  all  vegetables.  Fruits  and  berries,  espe- 
cially those  from  near  the  ground,  should  be  thoroughly  washed  before 
being  eaten.  Sheep  and  other  herbivora  become  infected  from  dogs  in 
ways  entirely  similar  to  those  of  man,  and  the  principle  of  prophylaxis 
is  the  same. 

The  number  of  dogs  should  be  diminished,  especially  stray  dogs, 
which  show  a  high  percentage  of  infection.  The  control  of  the  number 
of  dogs  and  their  habits  would  also  help  with  the  rabies  problem.  The 
better  management  of  slaughter  houses  would  not  only  help  control 
echinococcus  disease,  but  also  trichinosis  through  rats. 


FISH 

Fish  poisoning  or  ichthyotoxismus  is  most  frequent  in  Eussia,  Japan, 
and  the  West  Indies,  and  other  seacoast  countries  in  which  fish  forms 
a  large  part  of  the 'diet.  Some  of  these  poisons  are  now  better  under- 
stood, but  for  the  most  part  are  far  from  being  satisfactorily  explained. 


FISH  635 

Physiological  Fish  Poisoning. — Many  fish  are  always  poisonous,  that 
is,  normally  contain  a  substance  toxic  to  man;  some  develop  the  poison 
only  during  spawning  season.  Various  species  of  the  tetrodori  and 
diodon  frequently  cause  serious  and  fatal  poisoning  in  Japan.  In  Tokio 
alone  680  fatal  cases  out  of  933  were  reported  occurring  fn  1885-1893 
from  the  so-called  "fugu."  In  China  and  Japan  such  fish  are  sometimes 
taken  for  suicidal  purposes.  The  active  principle  in  fugu  poisoning 
resembles  curara.  The  poison  is  found  in  the  ovaries  and  testicles,  and 
is  called  "fugin."  Its  exact  chemical  nature  has  not  been  determined. 
The  symptoms  produced  are :  dyspnea,  cyanosis,  dilatation  of  the  pupils, 
relaxation  of  the  sphincters,  paralysis  of  speech,  dizziness,  salivation, 
and  vomiting.    Death  may  result  in  one  or  two  hours. 

Few  fish  containing  physiological  poisons  are  found  north  of  the 
tropics.  Some  fish,  such  as  shad  and  smelts,  are  preferred  during 
spawning  season.  However,  during  spawning  season  the  roe  of  differ- 
ent members  of  the  sturgeon  family,  of  the  pike,  and  the  barbel  have 
been  known  to  cause  pronounced  and  even  fatal  intoxication ;  the  symp- 
toms resemble  those  of  gastro-enteritis.  It  is  interesting  to  note  that 
even  the  codfish  (Gadus  morrhua),  if  eaten  raw,  has  caused  serious 
intoxication. 

Bacterial  Poisons. — Bacterial  poisoning  from  fish  is  fairly  common. 
The  fish  may  be  diseased,  or  when  caught  may  be  healthy,  but  the  bacteria 
gain  access  and  grow  throughout  the  meat  as  the  result  of  contamination 
or  imperfect  preservation.  Bacterial  diseases  among  fish  are  rather 
common  and  often  occur  as  epizootics.  In  almost  all  the  reported 
instances  of  injurious  action  resulting  from  bacteria  the  fish  has  been 
eaten  raw.  Bacteria  may  form  poisonous  substances  in  fish  closely 
resembling  botulismus.  Fish  caught  by  the  gills  in  nets  die  slowly  and 
decompose  rapidly.  They  are  of  inferior  fiavor  and  value  and  are  more 
liable  to  be  injurious  than  fish  taken  from  the  water  and  killed  at  once ; 
under  such  circumstances  they  remain  firm  and  retain  their  flavor  longer 
than  those  that  die  slowly.  In  some  parts  of  the  world  live  fish  in  tanks 
are  offered  for  sale  in  the  markets.  This  procedure  cannot  be  com- 
mended from  a  sanitary  standpoint,  for  the  tanks  are  apt  to  become 
dirty  and  the  fish  liable  to  sicken  and  die  slowly,  so  that  the  object  of 
purveying  only  live,  fresh,  and  wholesome  fish  is  largely  defeated.  It  is 
well  known  that  fish  decompose  readily  and  should,  therefore,  be  handled 
in  a  cleanly  manner  and  used  as  fresh  as  possible.  When  refrigerated 
the  temperature  should  be  low. 

The  Fish  Tapeworm. — The  principal  animal  parasite  conveyed 
through  fish  is  the  tapeworm,  Dihotliriocephalus  Jatus,  which  infects 
man  wherever  fresh  fish  forms  a  large  part  of  the  diet.  The  cysticercus 
or  larval  stage  is  found  in  the  muscles  and  organs  of  various  fresh  water 
fish,  particularly  pike,  perch,  and  several  members  of  the  salmon  family, 


636  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

and  when  partaken  of  by  man  develops  into  the  adult  tapeworm  in  the 
intestines.  The  adult  worm  is  also  found  in  cats  and  dogs  that  feed 
upon  fish. 

The  fish  tapeworm  produces  a  severe  anemia  resembling  pernicious 
anemia.  The  head  of  the  Dibothriocephalus  latus  is  armed  with  hooks 
and  attaches  itself  to  the  mucous  membrane  of  the  bowels.     Faust  and 

Tallqvist  have  shown  that  the  anemia  is  due 
"'^  to  an  hemolytic  action  caused  by  oleic  acid 

found  in  the  head  of  the  fish  tapeworm. 
Each  link  of  the  fish  tapeworm  has  a  rosette- 
shaped  uterus  in  the  median  line  and  a  spe- 
cial uterine  pore  from  which  eggs  are  con- 
stantly discharged  and  may  readily  be  found 
in  the  feces.  It  is  through  the  pollution  of 
the  streams  with  sewage  containing  the  eggs 
that  the  fish  become  infected. 
icijsticorcjs)  The  prevention  of  the  fish  tapeworm  con- 

FiQ.  79. — Dibothriocephalus       sists  in  proper  disposal  of  feces,  SO  as  to  pre- 
Latus.    the    Fish    Tape-     ^.^^^    ^^^^    contamination    of    fresh    water 

WORM. 

Produces  serious  anemia.  streams,  and  the  proper  cooking  of  fish. 

Paragonimus  westermanii,  a  fiuke  (dis- 
tome)  common  in  Japan  and  other  countries,  produces  very  serious 
lesions  in  the  lungs,  clinically  resembling  tuberculosis.  The  parasite  is 
contracted  through  a  microscopic  shrimp,  or  raw  fish  containing  the 
shrimp.^ 


SHELLFISH 

Shellfish  include  mollusks,  as  oysters,  clams,  mussels,  and  crustace- 
ans, as  lobsters,  crabs,  and  shrimp.  The  conditions  which  render  such 
food  injurious  are  much  the  same  as  those  discussed  in  connection  with 
fish.  Shellfish  may  be  diseased  when  taken  from,  the  water,  but  little 
is  known  of  the  diseases  of  shellfish  that  influence  men.  Shellfish  may 
be  perfectly  good  and  wholesome  when  fresh,  but  may  become  con- 
taminated and  poisonous  on  keeping,  especially  if  not  kept  cold. 

With  shellfish,  as  with  other  foods,  the  intermediate  products  of 
putrefaction  are  the  most  dangerous.  For  example,  mussels  that  have 
been  allowed  to  decompose  for  some  days  have  been  shown  to  be  free 
from  toxic  substances  (see  Ptomains).  Perhaps  the  most  important 
condition  bearing  upon  the  injurious  properties  of  shellfish  is  their 
habitat.     It  has  been  shown  repeatedly  that,  when  grown  or  kept  in 

*Koan  Nakagawa,  Jour,  of  Infectious  Diseases,  Vol.  18,  No.  2,  February, 
1916. 


SHELLFISH  637 

polluted  water,  they  acquire  poisonous  or  infectious  properties.  On 
being  transferred  to  fresh,  clean  water  they  may  lose  these  injurious 
characteristics.  It  is  claimed  by  some  observers  that  6  days,  by  others 
that  16  days,  in  clean  water  are  sufficient  for  mollusks  to  purge  them- 
selves of  typhoid  infection. 

It  is  now  well  known  that  oysters,  and  doubtless  other  mollusks, 
while  in  polluted  water,  may  take  up  large  numbers  of  different  kinds 
of  bacteria,  and  that  these  remain  alive  and  virulent  for  a  long  time. 
Herdman  and  Boyce  found  17,000  colonies  from  an  oyster  obtained 
from  the  neighborhood  of  a  drain  pipe.  Ordinarily  oysters  from  open 
waters  contain  less  than  100  colonies.  Oysters  contain  fewer  bacteria 
during  the  winter  months  (December  to  March),  when  they  probably 
hibernate.  Oysters  placed  in  polluted  waters  may  retain  the  typhoid 
bacillus  as  long  as  14  days  after  infection.  Klein  found  typhoid  to  per- 
sist in  oysters  from  2  to  3  weeks.  At  times  the  oysters  clean  themselves 
in  a  week ;  this  is  facilitated  by  clear,  clean,  running  water.  The  process 
by  which  the  oyster  rids  itself  of  bacteria  is  perhaps  both  mechanical 
and  biological. 

Gorham^  has  shown  that  during  cold  weather  (-40°  to  45°  F.)  oysters 
rest  or  hibernate;  the  ciliary  movement  ceases,  and  feeding  does  not 
occur;  and  the  oysters  become  practically  free  from  sewage  organisms 
even  when  lying  in  sewage-polluted  beds. 

Oysters  reflect  the  bacteriology  of  the  water  in  which  they  live  and 
grow.  The  bacteria  are  found  both  in  the  oyster  and  in  the  oyster 
liquid.  Oysters  from  clean  water  contain  few  bacteria  and  no  B.  coli; 
oysters  from  polluted  water  contain  many  bacteria  and  numerous 
B.  coli.  The  number  of  B.  coli  is  expressed  by  a  score  in  accordance 
with  the  method  of  the  American  Public  Health  Association,^  as 
follows : 

The  presence  of  B.  coli  in  each  oyster  of  five  examined  is  given  the 
following  values,  which  represent  the  reciprocals  of  the  greatest  dilutions 
in  which  the  test  for  B.  coli  is  positive: 

If  present  in  1  cc.  but  not  in  0.1  cc,  the  value  of  1. 

If  present  in  0.1  cc,  but  not  in  0.01  cc,  the  value  of  10. 

If  present  in  0.01  cc,  but  not  in  0.001  cc,  the  value  of  100,  etc 

The  addition  of  these  values  for  five  oysters  would  give  the  total 
numerical  value  for  the  sample  and  this  figure  would  be  the  score  for 
B.  coli. 

Oysters  scoring  less  than  50  are  usually  passed  as  satisfactory,  whereas 
those  scoring  over  140  are  regarded  as  polluted  by  sanitary  authorities. 

Both  typhoid  and  cholera  have  been  convincingly  traced,  to  infected 
oysters.     The  oysters  may  become  infected  where  they  grow  or  during 

^Gorham,  F.  P.:   Am.  Jour.  Pub.  Health,   1912,  II,   24. 
Mm.  Jour,  of  PuUic  Health,  11,  1912,  34. 


638  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

the  process  of  "fattening"  or  "floating,"  which  consists  in  soaking  them 
in  fresh  water  for  the  purpose  of  making  thera  more  plump  and  increas- 
ing their  size.  In  the  language  of  the  fishermen,  this  is  called  "float- 
ing," "plumping,"  "drinking,"  or  "laying  out."  On  account  of  the 
difference  in  osmotic  pressure  the  water  enters  the  cells  of  the  oysters 
and  certain  mineral  salts  pass  out.  While  the  oyster  increases  in  size 
and  weight  it  is  at  the  expense  of  the  natural  salt,  mostly  sodium  chlorid, 
which  the  oyster  contains.  Floating  is  practiced  by  the  majority  of 
oyster  growers,  partly  from  necessity,  for  purchasers  do  not  seem  to 
realize  that  an  oyster  in  its  natural  condition  is  never  very  thick  and 
has  a  slightly  greenish  color. 

It  may  be  stated,  as  a  general  rule,  that  oysters  and  other  shell- 
fish should  not  be  used  when  taken  from  water  which,  upon  bacter- 
iological examination,  would  render  it  unfit  if  used  for  drinking  pur- 
poses. 

Outbreaks  of  Typhoid  Fever  Traced  to  Oysters. — At  Middletown, 
Connecticut,  Professor  Conn  ^  showed  that  the  outbreak  of  typhoid 
fever  at  Wesleyan  University  during  1894  was  due  to  raw  oysters 
eaten  at  fraternity  banquets. 

The  increased  prevalence  of  typhoid  fever  in  Atlantic  City,  N.  J., 
during  the  summer  and  autumn  of  1902  was  traced  by  Pennington  ^ 
and  others  to  the  use  of  oysters  and  clams  floated  in  Penrose  Canal, 
which  was  highly  polluted  with  sewage. 

Dr.  Bulstrode  ^  during  1902  reported  21  cases  of  typhoid  fever  and 
118  cases  of  gastro-enteritis  from  a  total  number  of  267  guests  who 
had  eaten  raw  oysters  at  the  mayoralty  banquets  at  Winchester  and 
Southampton,  England,  on  November  10th  of  that  year.  The  oysters 
in  question  were  imported  from  France  and  "laid  down"  or  floated 
for  a  few  days  in  sewage-polluted  "drinking"  grounds  at  Emsworth. 
One  patient  who  developed  a  fatal  case  of  typhoid  ate  only  one  infected 
oyster,  while  others  ate  only  two  or  three  of  these  oysters. 

During  the  period  from  1894  to  1902,  inclusive.  Dr.  Newsholme,  of 
Brighton,  England,  investigated  241  cases  of  typhoid  fever  which  he 
ascribed  to  eating  infected  shellfish.* 

During  the  year  1902,  Thresh  and  Wood  ^  reported  in  the  county  of 
Essex,  England,  4  cases  of  typhoid  fever  and  21  cases  of  illness  due 
to  eating  Portuguese  oysters  sold  on  August  14  and  21  of  that  year. 

S.oper,^  1905,  showed  that  21  out  of  31  cases  of  typhoid  fever  at 
Lawrence,  Long  Island,  N.  Y..  could  be  traced  to  eating  oysters  and 

^Conn.  state  Board  of  Health  Report,  1894,  pp.  243-264. 
'"Philadelphia  Medical  Journal,  Nov.   1,  1902,  pp.  634-635. 
^  Local    Government    Board.    England.      32nd    Ann.    Report,    1902-3.      SupL 
App.  A,  pp.  129-189. 

^Brit.  Med.  Journal,  Aug.  8,  1903,  2:  295-297. 
'^The  Lancet,  Dec.  6,  1902,  2:   1567-1569. 
^Med.  News,  Feb.  11,  1905,  86:  241-253. 


SHELLFISH  639 

clams  which  had  been  floated  or  grown  in  Jamaica  Bay,  near  Inwood, 
Long  Island. 

Netter  ^  reported  33  cases  of  typhoid  fever  due  to  eating  oysters 
from  Cette  in  1907.  The  cases  were  very  virulent  in  character,  7  of 
the  33  resulting  fatally. 

Stiles  ^  investigated  an  outbreak  following  the  Minisink  banquet, 
held  at  Goshen,  IST,  Y.,  on  October  5,  1911,  and  showed  conclusively  that 
the  "Eockaway"  oysters  served  on  that  occasion  were  responsible.  There 
were  17  well-defined  cases  of  typhoid  fever,  with  one  death,  and  83 
cases  of  gastro-enteritis  (diarrhea)  traced  directly  to  eating  "Eock- 
away" oysters  from  Jamaica  Bay,  floated  at  Indian  Creek,  near  Canarsie, 
Long  Island,  N.  Y. 

Fuller  ^  reviewed  the  literature  on  this  subject  which  covered  more 
than  20  separate  outbreaks  due  to  infected  shellflsh  up  to  1904. 

In  Great  Britain  more  than  in  other  European  countries,  shellfish 
transmission  of  typhoid  fever  is  regarded  as  quite  frequent.  In  1896, 
Newsholme,  then  health  officer  in  Brighton,  published  careful  studies 
showing  that  30  per  cent,  of  the  typhoid  infections  occurring  in  that 
city  were  due  to  oysters  and  other  shellfish.  For  Belfast,  the  investi- 
gations of  Mair  showed  that  the  extensive  increase  of  typhoid  fever 
from  1897  to  1909  was  due  in  a  large  measure  to  infection  from  cockles 
gathered  along  a  shore  not  far  from  the  main  sewer  outlet. 

The  prevention  of  typhoid  and  similar  infections  through  oysters 
and  other  shellfish  consists  in  regulating  the  location  of  the  beds  and 
in  transferring  doubtful  oysters  to  a  clean  situation  in  clear  sea  water 
until  the  bacteria  have  perished  or  have  been  washed  away.  How  long 
this  may  take  is  somewhat  doubtful;  perhaps  a  week,  or,  better,  16 
days,  should  be  allowed.  "Floating"  should  be  prohibited,  especially 
in  water  of  doubtful  character.  Thorough  cooking  will  kill  all  the  non- 
spore-bearing  bacteria. 

Mussel  Poisoning. — Mytilus  edulis,  the  common  mussel,  is  a  rather 
frequent  source  of  poisoning  in  England  and  on  the  Continent.  Three. 
types  are  recognized  clinically:  (1)  gastro-enteric,  (2)  nervous,  and 
(3)  paralytic.  In  the  first  type  the  symptoms  are  nausea,  vomiting, 
diarrhea,  and  sometimes  choleraic  symptoms.  This  form  is  similar  to 
the  common  type  of  meat,  cheese,  and  other  acute  food  poisoning,  and 
when  due  to  mussel  poisoning  is  not,  as  a  rule,  fatal.  In  the  nervous 
type  the  symptoms  are  itching,  erythema,  urticaria,  angina,  dyspnea. 
Eecovery  from  this  form  usually  takes  place  in  a  few  days.  The  para- 
lytic type  suggests  curara.  This  is  less  frequent  and  more  dangerous 
than  the  gastro-enteric  or  nervous  types.    It  may  be  compared  to  botul- 

^The  Lancet,  Feb.  23,  1907,  1:  551. 

"  U.  8.  Dept.  of  Agriculture,  Bureau  of  Chemistry,  Bulletin  No.  156,  Sept. 
21,  1912. 

^  V.  8.  Bureau  of  Fisheries  Rept.,  1904,  pp.  189-238. 


640  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

ismus,  but  differs  in  rapidity  of  onset,  the  nature  of  the  symptoms,  and 
in  the  fact  that  boiling  does  not  destroy  the  poison.  Death  has  occurred 
in  15  minutes  after  eating  boiled  mussels.  A  notable  example  of  mussel 
poisoning  occurred  at  Wilhelmshaven  in  1885.  A  large  number  of  dock 
laborers  and  their  families  were  poisoned  shortly  after  eating  cooked 
mussels;  three  died.  The  mussels  were  examined  by  Brieger,  who  iso- 
lated several  basic  substances  or  ptomains,  one  of  which,  mytilotoxin, 
was  poisonous  to  animals,  causing  similar  symptoms.  Novy  considers 
this  a  true  instance  of  a  heat-resisting  alkaloidal-like  poison  or  ptomain 
in  a  sense  analogous  to  mushroom  poisoning.  Cats  and  dogs  eating 
poisonous  mussels  suffer  with  symptoms  similar  to  those  seen  in  man, 
namely,  paralysis,  coma,  and  death.  Eabbits  have  been  poisoned  by 
giving  them  the  water  in  which  the  mussels  have  been  cooked.  Under 
these  circumstances  they  may  die  in  a  minute. 

Miscellaneous. — In  addition  to  the  infections  noted,  the  following 
diseases  are  sometimes  transferred  from  the  flesh  or  organs  of  lower 
animals,  or  by  contact  with  the  lower  animals  in  various  ways:  tuber- 
culosis, anthrax,  glanders,  rabies,  actinomycosis,  foot-and-mouth  disease, 
cowpox,  ringworm,  and  various  pyogenic  and  septic  infections. 

Meat  may  occasionally  be  injurious  to  health  from  a  variety  of 
miscellaneous  causes.  Thus,  an  animal  that  has  died  of  arsenic  or  other 
poisonous  substance  may  contain  sufficient  of  the  poison  in  the  tissues 
to  affect  the  person  who  eats  part  of  the  flesh. 


"BOB-VEAL" 

"Bob-veal"  is  the  flesh  of  immature  calves,  that  is,  animals  less  than 
two  or  three  weeks  old.  "Bob- veal"  is  objectionable  from  humanitarian 
and  esthetic  grounds.  The  meat  is  flabby,  edematous,  soft.  The  con- 
nective tissue  is  gelatinous  and  is  present  in  greater  quantity  than  in 
mature  animals.  The  fat  is  reddish-gray  and  soapy,  the  meat  less  nutri- 
tious in  value,  as  it  contains  a  large  proportion  of  water.  On  account 
of  its  moist  and  soft  condition  "bob-veal"  has  a  greater  tendency  to  spoil 
than  the  flesh  of  mature  animals.  Young  calves  are  highly  susceptible 
to  a  number  of  infections,  particularly  diarrheal  diseases  and  infections 
which  enter  through  the  navel.  The  flesh  of  such  animals  may  convey 
microorganisms  belonging  to  the  "meat  poisoning"  or  paratyphoid  group. 

Ostertag  states :  "Putrefactive  and  pathogenic  microbes  find  a  ready 
media  for  luxuriant  growth  in  'bob-veal'  carcasses.  In  Switzerland 
27  persons  became  ill  from  eating  veal  of  a  calf  five  days  old,  which  had 
yellow  water  in  the  joints ;  one  patient  died.  In  the  Grand  Duchy  of 
Baden  from  1888  to  1891  5.3  calves  out  of  every  1,000  slaughtered  fur- 
nished meat  injurious  to  health." 


EGGS  641 

Bollinger  recites:  "In  the  epidemic  at  Andelfingen  450  people  be- 
came ill  and  10  died.  The  veal  which  was  consumed  was  suspected  and 
it  transmitted  its  poisonous  properties  to  beef  stored  with  it.  At  Ber- 
minstorf  8  people  died  from  eating  veal  from  a  calf  four  days  old.  At 
Morselle,  Belgium,  80  people  became  sick  from  eating  veal  of  two  calves 
with  diarrhea." 

It  is  a  well-known  fact  that  calves  under  three  weeks  old  have  umbili- 
cal wounds  which  are  liable  to  become  infected.  All  young  animals  are 
subject  to  such  infections,  since  nature  is  left  to  effect  the  healing  of  the 
wound.  The  weight  of  the  calf  is  often  taken  as  an  indication  of  its 
age.  Thus  a  calf  weighing  40  povmds  or  more  is  considered  mature, 
but  the  weight  is  a  poor  index  of  age.  The  condition  of  the  umbilical 
wound  usually  tells  the  tale.  There  are  no  sanitary  objections  to  the 
use  of  bob-veal,  other  than  the  likelihood  of  such  meat  containing  bac- 
teria belonging  to  the  meat  poisoning  group,  but  this  may  be  guarded 
against  by  care,  inspection  and  finally  by  thorough  cooking. 


EGGS 

Perhaps  no  article  of  diet  of  animal  origin  is  more  commonly  eaten 
in  all  countries  and  served  in  a  greater  variety  of  ways  than  eggs. 
Eggs  are  used  in  nearly  every  household  in  some  form  or  another.  It 
has  been  calculated  that  on  an  average  they  furnish  3  per  cent,  of  the 
total  food,  5.9  per  cent,  of  the  total  protein,  and  4.3  per  cent,  of  the 
total  fat  used  per  man  per  day.  When  we  speak  of  eggs  we  ordinarily 
mean  hen's  eggs,  but  the  eggs  of  ducks,  geese,  and  guinea  fowls  are 
used  to  a  greater  or  less  extent;  more  rarely  turkey's  eggs  and  some- 
times those  of  wild  birds.  Plover  eggs  are  prized  in  England  and 
Germany,  while  in  this  country  the  eggs  of  sea  birds,  such  as  gulls, 
terns,  herons,  and  murres,  have  long  been  gathered  for  food.  Other 
eggs  besides  those  of  birds  are  sometimes  eaten.  Turtle's  eggs  are  highly 
prized  in  most  countries  where  they  are  abundant.  The  eggs  of  the 
terrapin  are  usually  served  with  the  flesh  in  some  of  the  ways  of  prepar- 
ing it  for  the  table.  Fish  eggs,  especially  those  of  the  sturgeon,  are 
preserved  in  salt  under  the  name  of  caviare.  Shad  roe  is  also  a  familiar 
example  of  the  use  of  fish  eggs  as  food.  The  eggs  of  alligators,  lizards, 
serpents,  and  some  insects  are  eaten  by  races  who  lack  the  prejudices 
of  western  nations. 

Hen's  eggs  vary  considerably  in  size  and  appearance.  The  shell 
constitutes  about  11  per  cent.,  the  yolk  32  per  cent.,  and  the  white 
57  per  cent,  of  the  total  weight  of  the  egg.  The  egg-shell  consists  mainly 
of  carbonate  of  lime,  and  when  freshly  laid  is  covered  by  a  mucous  coat- 
ing. The  egg-white  consists  of  86.2  per  cent,  of  water,  12.3  per  cent. 
23 


642  ANIMAL  FOODS:  MEAT,  FISH,  EGGS,  ETC. 

nitrogenous  matter,  0.2  per  cent,  fat,  and  O.Ofi  ])er  (^ent  ash.  TIk^  yolk 
consists  of  49.5  per  cent,  water,  15.7  per  cent,  nitrogenous  matter,  33.3 
per  cent,  fat,  and  1.1  per  cent,  ash.^  These  are  averages;  different  eggs 
vary  somewhat  in  composition  from  each  other.  It  is  noteworthy  that 
eggs  contain  practically  no  carl)ohydrates. 

In  addition  to  fresh  and  refrigerated,  eggs  are  classified  in  the  trade 
as  "rots,"  "spots,"  "checks,"  "ringers,"  "chickens,"  "dirty  shells," 
"heated,"  or  "incubated,"  etc.  Eggs  are  assorted  by  inspection  and 
candling.  Candling  consists  in  holding  them  before  a  bright  light;  the 
egg  is  translucent  and  the  movable  yolk  may  clearly  be  discerned,  as 
well  as  the  air  space  which  is  always  at  the  larger  end.  A  practiced  eye 
quickly  detects  eggs  that  are  not  first  quality.  Rotten  eggs  are  distin- 
guished as  "red  rots"  and  "black  rots,"  depending  upon  the  kind  of 
putrefaction.  By  "spots"  are  understood  eggs  that  contain  opaque  spots 
under  the  light.  These  spots  usually  consist  of  local  growths  of  mold 
that  have  pentrated  a  crack  in  the  shell,  although  they  may  be  due  to 
coccidia,  embryos,  or  foreign  bodies.  "Checked"  eggs  are  those  which 
have  slight  cracks  or  nicks  in  the  shell.  "Eingers"  contain  small  embryos 
of  about  two  days'  growth,  which  are  flat,  disk-like,  and  reddish  in 
appearance.  "Chickens"  contain  embryos  of  larger  growth.  Eggs  with 
dirty  shells  are  undesirable  more  from,  esthetic  than  other  reasons.  The 
dirt  usually  consists  of  hen  excrement.  A  "heated"  egg  is  a  shrunken 
egg,  that  is,  an  egg  that  has  been  exposed  to  the  summer  temperature  for 
several  days.  Some  water  is  lost  by  evaporation  through  the  porous 
shell,  the  air  sac  on  the  end  has  increased  considerably  in  volume,  and  in 
many  instances  the  embryo  is  partly,  developed ;  therefore,  heated  eggs 
are  also  known  as  incubated  eggs.  Many  of  the  eggs  gathered  during 
the  hot  months  of  summer,  especially  in  July  and  August,  belong  to 
this  category.  These  eggs  are  much  less  desirable  than  the  spring  and 
fall  layings.  Eggs  are  also  graded  as  to  size,  the  very  small  eggs  being 
undesirable,  commanding  a  lower  figure  in  the  market.  Further,  eggs 
are  classified  as  strong-  or  weak-bodied,  depending  upon  how  they  "stand 
up"  when  broken  out. 

Eggs  as  they  come  from  the  hen  frequently  contain  bacteria,  worms, 
gravel,  blood  clots,  and  foreign  bodies  of  various  kinds.  Practically  all 
eggs  contain  bacteria,  although  numerous  observers  report  occasionally 
that  an  egg  is  sterile.  As  a  rule,  these  observations  are  based  upon 
planting  a  small  part  of  the  egg.  If  the  entire  egg  is  planted  a  growth 
is  almost  invariably  obtained.  Thus,  in  eighteen  freshly  laid  eggs  which 
I  recently  examined  every  one  of  them  contained  bacteria  in  the  yolk; 
two  of  them  contained  B.  coli.  Curiously  enough,  there  are  practically 
always  more  bacteria  in  the  yolk  than  in  the  white;  the  white  contains 

*  Pennington :  "A  Cliemical  and  Bacteriolooiea!  Study  of  Fresh  Eggs,"  Jour. 
Biol.  Chem.,  Vol.  VII,  No.  2,  Jan.,  1910,  p.   110. 


EGGS  G43 

some  bactericidal  property,  probably  similar  to  that  possessed  by  fresh 
blood.  The  bacteria  doubtless  gain  entrance  to  the  egg  while  in  the 
oviduct.  Pernot  ^  examined  the  eggs  from  over  the  size  of  a  pea  to  the 
perfect  egg  and  found  bacteria  at  every  stage.  It  is  well  known  that 
the  bacteria  may  also  get  into  an  egg  through  the  shell,  as  it  is  porous 
and  permeable.  When  the  shell  is  moist  and  dirty  the  chances  of  growth 
and  mold  piercing  it  are  increased.  Eggs  laid  in  the  summer  time 
(July  and  August)  contain  many  more  bacteria  than  those  laid  in  the 
spring,  fall,  and  colder  months.  It  is  well  known  that  summer  eggs 
do  not  keep  as  well  as  winter  and  spring  eggs. 

Very  large  quantities  of  eggs  are  now  broken  out,  mixed,  frozen, 
or  dried.  These  products  are  largely  used  by  bakers  and  others  who 
use  eggs  in  quantities. 

Of  all  foods,  so  far  as  known,  eggs  are  less  liable  to  convey  disease 
or  contain  harmful  properties  than  any  other  single  food  of  animal 
origin.  The  literature  is  singularly  free  of  instances  of  sickness  attrib- 
utable to  eggs.  There  is  no  known  infection  of  the  hen  transmissible  to 
man  through  its  egg.  Eggs  do  not  agree  with  some  people,  who  have  an 
"idiosyncrasy,"  so  that  a  very  small  quantity  will  bring  on  symptoms 
resembling  anaphylaxis.  This  condition  is  doubtless  an  instance  of 
specific  hypersusceptibility  to  egg  protein.  There  are  several  cases  on 
record  in  which  this  hypersusceptibility  has  been  cured  by  the  adminis- 
tration of  pills  or  candy  containing  at  first  infinitesimal  amounts  of 
egg-white,  gradually  increasing  the  amount.  The  entire  treatment 
should  extend  over  a  period  of  months.  In  this  way  an  immunity  may 
be  established  in  man  precisely  analogous  to  the  immunity  which  may 
be  established  by  repeated  injections  of  an  alien  protein  into  guinea-pigs. 

*  "Investigation  of  the  Mortality  of  Incubator  Chicks,"  Bull,  103,  Oregon 
Agr.  College  Exp.  Station. 


CHAPTER  IV 
PLANT  FOODS 

Vegetable  substances  may  be  injurious  to  health  from  several  causes. 
Many  plants  contain  a  physiological  poison,  such,  for  example,  as  aconite, 
strychnin,  ricin,  abrin,  muscarin,  and  a  long  list  of  other  substances 
normally  present.  Certain  plants  contain  parasites,  such  as  rye,  which 
causes  ergotism.  The  plant  may  be  entirely  wholesome  when  fresh,  but 
may  develop  poisons  as  the  result  of  bacterial  action.  Changes  occur  in 
vegetables  entirely  similar  to  those  which  occur  in  nitrogenous  animal 
products,  with  the  production  of  poisons  of  different  kinds.  The  same 
microorganisms  that  produce  "ptomains"  or  other  toxic  substances  in 
meat  when  introduced  into  vegetables  act  in  the  same  manner.  The 
richer  the  vegetable  in  nitrogen  the  more  likely  is  it  to  acquire  such 
poisonous  properties.  Carbohydrates  retard  or  suppress  this  action; 
therefore,  vegetables  containing  large  amounts  of  carbohydrates  arc 
less  apt  to  become  dangerous.  Botulism  may  result  from  beans  or  other 
vegetables  containing  a  high  percentage  of  protein. 

Certain  vegetables,  such  as  lettuce,  celery,  water  cress,  radishes,  and 
similar  plants,  eaten  raw  may  convey  typhoid  fever,  cholera,  dysentery, 
both  amebic  and  bacillary,  the  eggs  and  larvae  of  animals  parasites,  and 
other  infections. 

All  vegetables  which  are  eaten  raw  should  be  washed  thoroughly 
beforehand,  otherwise  they  may  be  contaminated  with  manure  and  other 
impurities  or  the  excrement  of  domestic  animals  which  have  been  roam- 
ing in  the  garden.  The  larvae  of  tapeworms  and  roundworms  have  been 
transmitted  to  man  in  this  manner.  Water  from  foul  wells  is  used 
sometimes  for  sprinkling  gardens,  and  it  is  possible  for  typhoid  and 
other  intestinal  infections  to  be  spread  by  this  means  when  the  vege- 
tables are  eaten  raw. 

An  unbalanced  ration  consisting  largely  of  polished  rice  causes  beri- 
beri. Pellagra  is  also  due  to  a  faulty  diet.  Strawberries,  tomatoes  and 
cereals  are  apt  to  cause  urticaria  and  other  anaphylactic  symptoms  in 
susceptible  persons. 


POISONING  FROM  PLANT  FOODS 

Ergotism. — Ergotism  is  a  form  of  food  poisoning  brought  on  by  pro- 
longed use  of  meal  made  from  grain  contaminated  with  the  Claviceps 

644 


POISONING  FROM  PLANT  FOODS  645 

purpurea.  The  fungus  develops  in  the  flowers  of  rye  and  other  grains. 
The  chief  source  of  the  poisoning  in  man  is  from  rye,  in  which  case 
the  fungus  may  entirely  replace  the  grain.  Ergotism  is  practically 
unknown  in  this  country,  but  in  Europe  it  is  still  occasionally  met  with, 
although  not  to  the  same  extent  as  in  former  times.  From  ergot  Robert 
was  able  to  isolate  three  poisonous  substances,  sphacelinic  acid,  cornutin, 
and  ergotin.  Sphacelinic  acid  is  a  non-nitrogenous,  unstable  body  and 
is  believed  to  be  the  active  agent  in  contracting  the  blood  vessels.  Cornu- 
tin is  also  an  active  alkaloid  and  produces  vasomotor  contraction. 
According  to  Novy,  more  recent  investigations  have  made  it  probable 
that  there  are  other  substances  present  which  constitute  the  real  toxic 
agent.  Thus,  Jacoby  obtained  a  non-nitrogenous  resin  sphacelotoxin 
which  he  regards  as  the  specific  poison.  The  intoxication  -may  have  an 
acute  or  chronic  course,  and  in  either  type  the  symptoms  may  be  nervous 
or  convulsive,  or  else  they  may  be  trophic  or  gangrenous  in  char- 
acter. 

The  presence  of  the  sclerotium  may  be  suspected  from  the  color  of 
the  meal,  which  is  grayer  than  usual  and  often  shows  violet-colored 
specks.  The  addition  of  potassium  hydroxid  with  heat  produces  an 
odor  of  trimethylamin  resulting  from  the  breaking  up  of  the  grain  con- 
taining chinolin.  Further,  the  grain  contains  a  dye  which  is  soluble 
in  alcohol  or  ether.  To  10  grams  of  the  meal  add  10  c.  c.  of  ether  and 
20  drops  of  dilute  sulphuric  acid.  Shake  well  and  filter  after  half  an 
hour.  Then  add  several  drops  of  a  saturated  solution  of  sodium  bicar- 
bonate, which  dissolves  out  all  the  coloring  matter. 

Lathyrism. — Lathyrism  or  vetch  poisoning  is  a  rather  rare  condition 
met  with  in  some  parts  of  Europe,  notably  Austria  and  Italy,  in  north- 
ern Africa,  and  in  India.  The  vetch  seed  is  ground  in  the  form  of 
meal  and  used  as  a  partial  substitute  for  that  of  wheat.  The  seed  is 
popularly  known  as  chick-pea.  The  vetch  seeds  are  obtained  chiefly 
from  Lathyrus  sativus  and  Latliyi'us  cicera.  The  eating  of  bread  pre- 
pared from  meal  containing  the  seeds  of  the  lathyrus  is  followed  by 
sudden  and  severe  pains  in  the  lumbar  region,  girdle  sensation,  motor 
paralysis  of  the  lower  extremities,  tremor,  and  fever.  The  nature  of 
the  poison  is  not  known,  but  it  is  probably  of  the  nature  of  a  toxalbumose, 
of  which  ricin  and  abrin,  the  poisons  of  the  castor  bean  and  the  jequirity 
bean  respectively,  are  well-known  examples. 

Mushroom  Poisoning. — The  ill  effects  from  eating  mushrooms  are  due 
to  mistaking  the  poisonous  for  the  edible  species.  The  number  of 
species  of  poisonous  mushrooms  which  are  capable  of  causing  death  is 
not  very  great.  Amanita  and  volvaria  are  the  most  poisonous  genera, 
and  are  the  ones  usually  involved  in  the  fatal  accidents.  The  following 
is  a  list  of  the  most  poisonous  mushrooms  known,  and  all  that  are  likely 
any  time  to  produce  death: 


640  PLANT  FOODS 

Amanita  phalloides  Fr. 
Amanita  citrina  Pers. 
Amanita  verna  Bull. 
Amanita  virosa  Fr. 

"Volvaria  gloiocephala,  var.  speciosa  (Fr.). 
Amanita  muscaria   (L.)   Pers. 
Amanita  pantherina  DC. 
Lactarins  torminosus  (Schaeff.)  Fr, 
Lactarius  rufus  Fr. 
Lactarius  zonarius    (Bull.)    Fr, 
Lactarius  pyrogallus  (Bull.)  Fr. 
Eussula  emetica  Fr. 
•  Eussula  queletii  Fr. 
Eussula  foetens  (Pers.)  Fr. 
Boletus  felleus  Bull. 
Boletus  sataiius  Lenz. 
Boletus  erythropus  Cke. 
Boletus  luridus  Schaeff. 
Entoloma  lividum  Bull. 

Amanita  phalloides  and  Amanita  muscaria  are  exceedingly  poison- 
ous, dangerous  and  seductive  species,  responsible  for  most  of  the  deaths 
from  toadstool  eating.  Amanita  phalloides,  because  of  its  white  color, 
is  mistaken  for  the  common  mushroom,  Agaricus  campester.  Amanita 
phalloides  does  not  grow  in  the  woods,  neither  has  it  wliite  gills,  nor 
white  spores,  nor  a  volva  at  the  base  of  tlie  stem.  No  dependence,  how- 
ever, should  be  placed  upon  color,  size,  shape  or  general  appearance.  It 
requires  a  trained  mycologist  to  distinguish  one  species  from  another.^ 

The  first  historic  instance  of  mushroom  poisoning  occurred  in  the 
family  of  the  Greek  poet,  Euripides,  who  lost,  in  one  day,  wife,  daughter 
and  two  sons.  Among  others  whose  lives  have  been  sacrificed  through 
ignorance  may  be  mentioned  Pope  Clement  VII,  the  Emperor  Jovian, 
Emperor  Charles  VI,  Berronill  of  Naples,  the  widow  of  Tsar  Alexis, 
and  the  Princess  of  Conti. 

Mushrooms  contain  at  least  four  classes  of  poisons:  (1)  a  toxin 
represented  by  aminata -toxin,  studied  especially  by  Ford,  and  some- 
what resembling  the  toxin  of  botulismus;  (2)  muscarin,  an  alkaloidal- 
like  substance,  resembling  pilocarpin;  (3)  a  hemolytic  poison;  and  (4) 
a  number  of  poisons  more  or  less  ill  defined.  These  poisons  do  not 
all  occur  in  any  one  species,  but  are  foand  singly  and  in  various  com- 
binations in  the  different  genera  and  species. 

Amanita   toxin  was    found   by    Ford  ^   in   Amanita  plialloides   and 

*The  subject  has  been  discussed  since  1886  in  the  Bulletin  de  la  Societe 
Mycologique  de  France. 

^Wm.  H.  Ford:     Jour.  Exp.  Med.,  May  26,  1906,  VIII,  3,  p.  437. 


POISONING  FEOM  PLANT  FOODS  647 

Amanita  verna.  It  is  soluble  in  alcohol ;  it  is  not  influenced  by  boiling, 
and  resists  the  action  of  the  gastric  juice.  It  is  one  of  the  most  power- 
ful poisons  of  organic  origin  known.  Four-tenths  of  a  milligram  will 
kill  a  guinea-pig  within  34  hours.  This  toxin  is  evidently  the  active 
principle  in  mushroom  poisoning  caused  by  A.  phaUoides  and  other 
species.  The  toxin  acts  upon  the  heart,  kidneys  and  muscles,  and  recov- 
ery from  small  doses  is  slow.     Death  usually  results. 

Amanita  plialloides,  the  '"'white  or  deadly  amanita,"  is  the  cause  of 
the  greatest  number  of  cases  of  mushroom  poisoning,  if  we  include  in 
this  group  A.  verna,  A.  bulbosa,  A.  alba,  A.  virescens,  A.  mappa,  and 
many  other  species  known  by  various  names  in  difl'erent  localities.  Fatal 
poisoning  takes  place  when  the  fungi  are  eaten  raw  or  cooked.  Two 
or  three  deadly  amanitas  are  sufficient  to  cause  profound  illness  with 
fatal  outcome  in  an  adult.  Plowright  reports  the  death  of  a  child  of 
twelve  from  eating  a,  third  of  the  pileus  of  a  small  raw  plant. 

The  symptoms  come  on  after  a  period  of  incubation  of  6  to  15  hours. 
The  first  sign  of  trouble  begins  with  sudden  pain  of  great  intensity 
localized  in  the  abdomen  accompanied  by  thirst,  vomiting,  and  profuse 
watery  diarrhea.  x4fter  3  or  4  days  in  children,  or  from  6  to  8  days 
in  adults,  the  victim  sinks  into  a  profound  coma. 

Muscarine  is  the  active  poisonous  principle  of  Amanita  muscaria 
{Agaricus  muscarim).  Muscarine  (CH3)3N.CIl2CH(0H)20H  is  a 
syrupy  alkaloidal-like  substance  obtainable  in  crystallizable  form  as 
a  hydrochlorid.  It  was  first  isolated  by  Schmiedeberg  and  Koppe  in 
1869.  Chemically  it  evidently  is  an  ammonia  substitution  compound 
and  is  classed  with  the  ammonia  bases.  It  may  be  prepared  synthetically 
by  the  oxidation  of  cholin. 

The  physiological  action  of  muscarine  resembles  pilocarpin  very 
closely.  It  acts  especially  upon  the  terminal  nerve  endings.  Atropin 
is  an  almost  perfect  physiological  antidote  for  muscarine. 

The  symptoms  of  muscarine  poisoning  come  on  quickly,  often  within 
15  minutes,  and  consist  of  salivation,  excessive  perspiration,  and  flow  of 
tears;  nausea,  retching  and  vomiting,  pain  in  the  abdomen,  violent  move- 
ment of  the  intestines,  causing  profuse  watery  evacuations.  The  pulse 
is  sometimes  quickened,  sometimes  very  slow  and  irregular.  The  pupil 
is  contracted,  respiration  often  quickened,  and  dyspneic.  Dizziness 
and  confusion  of  ideas  are  often  complained  of,  but  mental  symptoms 
are  not  so  conspicuous  as  those  from  the  peripheral  organs.  Eventually 
the  respiration  becomes  slower,  great  muscular  weakness  supervenes^  but 
consciousness  remains  more  or  less  clear  until  the  breathing  ceases. 

The  peasants  of  the  Caucasus  prepare  an  intoxicating  beverage  from 
A.  muscaria  which  produces  wildly  riotous  drunkenness.  Death  from 
muscarine  orgies  is  not  uncommon  in  this  part  of  Eussia.  Similar  spe- 
cies in  North-eastern  Asia  are  also  used  as  an  intoxicant.     The  poison 


648  PLANT  FOODS 

is  excreted  in  the  urine  which  is  sometimes  later  consumerl  for  its  intoxi- 
cating effect.  It  is  probable  that  a  sort  of"  tolerance  to  miiscarin  is 
developed  among  the  habitual  users  of  the  muscaria  decoction. 

The  alkaloid  is  soluble  in  water  and  poisoning  may  be  prevented 
by  soaking  the  mushrooms  in  water  slightly  acidulated  with  vinegar 
before  they  are  cooked. 

Hemolysin.  Kobert  in  1891  obtained  a  hemolytic  substance  by  alco- 
holic precipitation  from  A.  phalloides.  This  substance  he  named  "phal- 
lin";  it  is  an  extremely  com,plicated  substance,  having  the  nature  of 
a  glucosid ;  that  is,  it  contains  sugar  in  its  molecule.  It  is  not  always 
present  in  A.  phalloides  and  is  probably  not  an  essential  poison  in  this 
mushroom,  for  its  activity  is  destroyed  at  70°  C.  and  also  by  the 
action  of  the  gastric  juice.  A  high  grade  immunity  can  be  estab- 
lished in  animals  to  the  hemolytic  substance.  Ford  obtained  an  anti- 
hemolysin  which  completely  neutralizes  the  blood-laking  properties  of 
this  poison. 

The  hemolysin  probably  plays  a  small  if  any  role  in  human  intoxi- 
cation. A.  ruhesceiis,  considered  by  the  majority  of  mycologists  to  be 
an  edible  mushroom,  contains  a  powerful  hemolysin.  On  the  other  hand, 
a  hemolytic  poison  is  found  in  Helvella  or  Gyrpmytra  esculenta  which 
occurs  rarely  in  this  country.  The  active  principle  is  helvellic  acid 
(Boehm  and  Kiilz)  which  produces  in  dogs  all  the  signs  of  hemolytic 
intoxication  similar  to  those  sometimes  found  in  man. 

A  great  many  other  poisons  have  been  studied  in  mushrooms.  For 
example  Harmsen  has  found  a  convulsive-producing  substance  asso- 
ciated with  muscarin  in  Amanita. 

Potato  Poisoning,. — It  has  long  been  known  that  potatoes  contain 
normally  a  very  small  amount  (about  O.OG  per  cent.)  of  the  poisonous 
principle  solnnin,  but  it  is  only  quite  recently  that  it  has  been  discovered 
that,  under  certain  circumstances,  they  may  contain  the  poison  in 
amounts  sufficient  to  cause  grave  disturbance  of  the  system.  The  increase 
is  due  to  the  action  of  at  least  two  species  of  bacteria,  Bacterium  solani- 
ferum  non- color abile  and  Bacterium  solaniferum.  colorabile,  and  occurs  in 
those  tubers  which,  during  growth,  have  lain  partially  exposed  above 
ground,  and  in  those  which,  during  storage,  have  become  well  sprouted. 
The  most  extensive  outbreak  of  potato  poisoning  recorded  occurred  in 
1899  in  a  German  regiment,  fifty-six  members  of  which,  after  eating 
sprouted  potatoes,  were  seized  with  chills,  fever,  headache,  vomiting, 
diarrhea,  colic,  and  great  prostration.  Many  were  jaundiced  and  several 
collapsed,  but  all  recovered.  Samples  of  the  remaining  potatoes  yielded 
0.38  per  cent,  of  solanin,  and  this  would  indicate  that  a  full  portion  must 
have  contained  about  five  grains  (Osier). 


BERIBERI  649 


BERIBERI 


Our  knowledge  of  beriberi  ^  is  now  sufficient  to  place  this  scourge  of 
the  tropics  among  the  preventable  diseases.  Long  associated  with  a  defi- 
cient diet,  it  is  now  evident  that  beriberi  is  a  disease  due  to  an  unbal- 
anced or  monotonous  diet  made  up  largely  of  polished  rice,  that  is,  rice 
without  the  pericarp.  The  disease  may  be  prevented  or  cured  by  the 
administration  of  rice  bran,  or  other  substances  containing  vitamins. 

Beriberi,  or  kakke,  is  a  specific  form  of  multiple  peripheral  neuritis 
occurring  endemically,  or  as  an  epidemic,  in  most  tropical  or  subtropical 
climates.  It  is  characterized  clinically  by  disturbances  of  motion,  sensa- 
tion, dropsy,  and  affection  of  the  heart.  The  sj^mptoms  are  attributable 
to  degenerative  changes  in  many  of  the  peripheral  nerves,  being  a  toxic 
neuritis  similar  in  many  respects  to  that  produced  by  alcohol,  arsenic, 
and  other  poisons  as  the  toxone  of  diphtheria.  Three  types  of  the  disease 
are  recognized:  (1)  the  paraplegic,  or  dry;  (2)  the  dropsical,  or  wet; 
and  (3)  the  mixed.  The  course  of  the  disease  is  uncertain;  sudden 
death  owing  to  involvement  of  the  heart  is  a  common  termination. 
Recovery  is  frequent  and  may  be  complete;  it  is  promoted  by  change 
of  climate,  improvement  in  the  sanitary  surroundings,  and  especially  by 
change  of  diet  containing  vitamins. 

Takaki,  the  surgeon  general  of  the  Japanese  Navy,  believed  as  early 
as  1883  that  beriberi  was  due  to  nitrogen  starvation.  He  was  of  the 
erroneous  opinion  that  the  disease  was  practically  abolished  from  the 
Japanese  Navy  simply  by  allowing  a  larger  portion  of  nitrogenous  food, 
whereas  we  now  know  that  the  important  change  in  the  diet  consisted 
in  a  reduction  of  the  amount  of  polished  rice  consumed  and  an  increase 
of  meat,  fish,  vegetables,  including  beans,  and  the  addition  of  milk  and 
flour.  This  dietetic  change  was  furthermore  coincident  with  other  sani- 
tary reforms.  In  former  years  one-fourth  of  the  personnel  of  the 
Japanese  Navy  suffered  from  beriberi.  Since  1884  it  has  been  prac- 
tically unknown. 

Rice. — A  grain  of  rice,  after  removal  from  the  husk,  consists  of  three 
parts :  ( 1 )  an  outer  layer  called  the  pericarp,  which  is  a  very  thin  mem- 
brane. The  color  of  the  pericarp  varies  in  different  species  of  rice, 
from  white  to  yellow,  through  the  browns  and  reds,  to  almost  black; 
(2)  the  middle  layer,  called  the  subpericarpal  or  aleurone  layer,  which 
is  composed  of  cubical  cells  filled  with  aleurone  and  fat ;  it  contains  very 
few  starch  grains.  Practically  all  of  the  fat,  and  the  greater  part  of  the 
albumin  of  the  grain  is  confined  to  this  middle  layer;  the  pericarp  and 
subpericarp  contains  practically  all  the  phosphorus,  and  also  all  the  vita- 

^Vedder,  "Beriberi,"  Wm.  Wood  &  Son,  1913.  Contains  a  complete  descrip- 
tion and  bibliography  of  the  disease. 


650 


PLANT  FOODS 


mins,  or  orfraiiic  nitrogenous  ])asos.  ('■■>)  The  bulk  of  the  grain,  which 
consists  of  the  innermost  portion,  is  filled  with  starch  grarmies.  The 
embryo  is  absent  in  milled  rice. 

Eice  is  first  husked  between  large  horizontal  revolving  stone  disks. 
The  chaff  is  winnowed  out.  This  part  of  the  process  chips  off  only 
a  small  part  of  the  pericarp.  The  grain  is  then  milled  by  means  of  a 
vertical,  revolving  conical  stone,  around  Avhich  is  a  close  fitting  metal 
gauze  case.  Friction  between  the  stone  and  the  case  rubs  off  the  pericarp 
and  the  aleurone  layer.  The  dust  escaping  is  called  rice  polishing  or 
rice  bran,  which  is  used  in  the  prevention  and  treatment  of  beriberi. 
In  the  so-called  "highly  milled  grades"  of  rice,  such  as  are  commonly 


|-  = 


Fig.  80. — Sections  Through  Seeds  of  Rice  (I),  Wheat  (II),  and  Corn  (III),  Showing 
THE  Protein  (P)  and  the  Starch  (S)  of  the  Seeds,  and  Their  Germ  (E)  ;  1,  2 
AND  3,  the  Seeds  as  Seen  from  the  Outside,  Natural  Size. 


seen  in  the  markets  of  the  world,  all  of  the  pericarp  and  most  of  the 
aleurone  layer  have  been  removed.  The  last  process  in  the  treatment 
or  rice  is  the  polishing  with  buffers  covered  with  long  wooled  sheep  skin. 
This  removes  the  dust,  and  leaves  a  clean,  white  grain.  Talcum  and 
glucose  are  often  added  to  give  a  shiny  surface.  By  undermilled  rice  is 
understood  rice  retaining  a  large  share  of  the  pericarp  and  aleurone 
layers. 

Many  physicians  who  have  studied  the  subject  in  Japan,  Java,  the 
Phili^Dpines,  and  other  countries  have  long  regarded  rice  as  the  impor- 
tant cause  of  the  disease.  In  the  prisons  of  Java  the  proportion  of  cases 
is  1-39  when  rice  is  eaten  completely  shelled,  1-10,000  when  the  grain 
is  eaten  with  its  pericarp.  In  some  places  the  disease  has  disappeared 
when  the  unshelled  rice  has  been  substituted  for  the  shelled. 

Eijkman,  in  ISDO,  showed  that  a  disease  resembling  beriberi  charac- 


BEKIBEEI  651 

terized  by  degeneration  of  the  peripheral  nerves  may  be  produced  in  fowl 
by  feeding  them  on  white  or  polished  rice.  These  results  were  later 
confirmed  by  Grijns  (1900)  and  Halshoff  Pol  (1901),  but  a  great  im- 
petus was  given  to  the  study  of  the  disease  by  Fraser  and  Stanton  who, 
in  1909-11,  clearly  demonstrated  that  the  disease  is  brought  about  by 
a  diet  of  white  or  polished  rice.  These  investigators  took  300  Japanese 
laborers  into  a  virgin  jungle,  where  they  occupied  new  and  sanitary 
quarters.  After  excluding  the  existence  of  beriberi  by  a  careful  exam- 
ination of  each  person,  they  were  divided  into  two  parties  of  equal  num- 
bers. One  party  received  polished  rice  as  the  staple  article  of  diet,  while 
the  other  party  received  undermilled  rice  with  pericarp.  In  three  months 
beriberi  appeared  among  the  members  of  the  party  receiving  polished 
rice.  When  a  certain  number  of  cases  had  been  noted,  polished  rice  was 
discontinued,  and  thereafter  no  cases  occurred.  Xo  sign  of  the  disease 
appeared  among  the  party  receiving  undermilled  rice.  The  conditions 
were  then  reversed.  The  party  hitherto  on  undermilled  rice  were 
given  polished  rice,  and  after  a  somevrhat  longer  interval  beriberi 
broke  out  in  this  group  also.  This  outbreak  also  ceased  on  discontinuing 
the  issue  of  polished  rice.  Again  no  sign  of  the  disease  appeared 
among  the  control  party  receiving  undermilled  rice.  Place  infection  and 
communicability  were  excluded  by  transferring  individuals  suffering 
from  beriberi  from  one  group  to  the  other  from  time  to  time. 

The  same  changes  in  diet  which  avoid  or  cure  beriberi  in  man  act  in 
a  similar  manner  in  respect  to  polyneuritis  in  fowl.  It  has  now  been 
established  that  polished  rice  causes  beriberi  if  the  diet  is  based  almost 
exclusively  on  this  foodstuff,  but  that,  if  a  sufficient  amount  of  other 
things,  such  as  fresh  meat  and  vegetables,  are  taken  with  it,  the  disease  is 
not  produced.  In  the  polishing  of  rice  the  pericarp  or  cortical  portion 
of  the  grain  is  removed  and  the  embryo  is  discarded.  It  is  evident  that 
these  discarded  portions  contain  some  substance  (vitamin)  essential  to 
a  well-balanced  ration.  It  has  been  found  that  most  of  the  phosphorus 
is  contained  in  the  pericarp.  The  amount  of  phosphorus  is  a  good 
guide  in  the  selection  of  a  beriberi-preventing  rice.  In  the  East,  rice  is 
regarded  as  unsafe  if  it  contains  upon  analysis  a  content  of  less  than  0.35 
per  cent,  of  phosphorus  pentoxid.  It  is  not,  however,  the  absence  of 
the  phosphorus  which  induces  beriberi,  but  the  amount  of  phosphorus,  as 
phosphorus  pentoxid  (P2O5)  may  be  taken  as  an  index  of  the  degree 
to  which  the  rice  has  been  polished. 

Funk^  in  1911,  isolated  a  substance  from  rice  polishings  that  pre- 
vents and  cures  polyneuritis  gallinarum.  Funk  obtained  a  crystalline 
organic  base  (Ci-Hgo^STjO^)  by  precipitation  with  phosphotungstic  acid, 
and  also  by  silver  nitrate  in  the  presence  of  baryta.     The  same  base  was 

^Jour.  of  Physiol,  1911,  XLIII,  26;  also  Casimir  Funk,  Die  Vitamine,  Wies- 
baden, 1914. 


653  PLANT  FOODS 

subsequently  obtained  from  yeast  and  other  foods.  About  0.02  gram  of 
this  substance  to  pigeons  suffering  with  polyneuritis  affects  a  rapid  cure. 
Funk  calls  the  substance  in  question  "vitamin." 

The  recent  work  of  Fraser  and  Aron,  Breaudat  and  Denier,  Dehaan, 
Heiser,  and  others  leaves  little  doubt  concerning  the  relation  of  polished 
rice  to  beriberi.  Heiser  ^  reports  that,  prior  to  February,  1910,  polished 
rice  was  commonly  used  in  the  Culion  leper  colony.  The  deaths  from 
all  cases  between  February.  1909,  to  1910  were  898,  of  which  309  were 
due  to  beriberi.  From  February,  1910,  to  February,  1911,  unpolished 
rice  was  used,  and  there  were  369  deaths,  a  reduction  of  over  one-half 
the  death  rate  for  the  previous  year.  It  is  significant  that  there  were 
no  deaths  from  beriberi  during  this  interval  following  the  use  of  unpol- 
ished rice.  Heiser  further  reports  50  cases  of  beriberi  treated  by  giving 
daily  15  grams  of  rice  polishings.  Improvement  was  noticed  in  all  except 
two  very  advanced  cases.  These  results  have  been  so  striking  that  the 
Philippine  government  has  drafted  a  bill  providing  for  the  general  use 
of  unpolished  rice;  that  is,  rice  containing  at  least  0.4  per  cent,  of  phos- 
phorus as  phosphorus  pentoxid,  and  the  levying  of  a  tax  upon  polished 
rice  which  makes  its  sale  practically  prohibitive.  Breaudat  and  Denier  ^ 
at  Saigon,  in  Indo-China,  report  good  results  from  the  prophylactic  use 
of  rice  bran.  Forty  grams  are  administered  daily  in  the  ordinary  food. 
No  case  of  beriberi  developed  among  49  native  soldiers  who  took  bran, 
while  17.4  per  cent,  of  311  controls  developed  the  disease. 

The  prevention  of  beriberi  in  the  Philippine  Islands  based  upon  the 
rice  theory  is  little  short  of  marvelous.  The  disease  has  been  entirely 
eliminated  from  the  Philippine  native  scouts  owing  to  the  reduction  in 
the  amount  of  rice  from  20  to  16  ounces,  a  substitution  of  undermilled 
rice  for  the  polished  article,  and  the  addition  of  a  legume  to  the  dietary. 
In  1908  and  1909  there  were  600  cases  of  beriberi  annually.  In  the 
entire  17  months  since  the  alteration  in  the  ration  went  into  effect  there 
have  been  but  7  cases  of  the  disease ;  occasionally  cases  may  be  expected 
owing  to  disobedience  of  instructions. 

Infantile  beriberi  is  also  common  in  the  Philippines,  and  may  like- 
wise be  prevented  and  even  curved  with  rice  bran. 

Prevention. — The  prevention  of  beriberi  consists  in  substituting  the 
use  of  whole  rice  for  the  polished  grain;  also  in  improving  the  general 
quality  of  the  food  and  in  providing  for  better  balanced  dietaries,  espe- 
cially adding  to  the  dietary  articles  containing  vitamins  such  as  fresh 
meat,  vegetables,  milk,  eggs  and  fruit.  The  prophylactic  value  of  rice 
polishings  added  to  the  ordinary  diet  must  be  borne  in  mind. 

It  seems  a  simple  thing  to  substitute  undermilled  for  highly  milled 
or  polished  rice,  but  it  will  require  a  long  and  patient  campaign  to  make 

Vow.  A.  M.  A.,  Vol.  LI,  1911,  p.  1237. 
'Ann.  de  I'Inst.  Pasteur,  Feb.,  1911,  No.  2. 


PELLAGRA  653 

a  change  which  is  utterly  at  variance  with  the  economic  and  social  habits 
of  entire  nations  who  have  for  many  years  considered  the  polished  rice 
as  the  best  quality,  and  generally  i^urchased  it  by  preference.  Much  may 
be  accomplished  through  taxation  of  the  highly  milled  rice,  through 
education,  and  also,  in  part,  through  law. 

It  should  be  borne  in  mind  that  beriberi  may  be  produced  by  a 
monotonous  diet  of  other  starchy  substances,  such  as  wheat  flour  (Little 
and  Strong).  A  varied  diet  is,  therefore,  one  of  the  prime  essentials 
in  the  prevention  of  beriberi.  A  diet  almost  exclusively  of  substances 
other  than  rice  will  cause  beriberi ;  thus,  Wellmann  and  Bass  ^  produced 
polyneuritis  of  fowls  with  sago  in  20  days;  boiled  white  potatoes,  24 
days;  boiled  milled  rice,  27  days;  corn  starch,  32  days;  white  flour, 
34  days;  corn  grits,  36  days;  oiled  sweet  potatoes,  38  days;  cream  of 
wheat,  39  days;  puffed  rice,  39  days;  macaroni,  40  days.  These  experi- 
ments plainly  indicate  that  legislation  or  regulation  against  the  sale 
of  polished  rice  in  our  country  are  not  M'arranted.  It  is  plain  that  sev- 
eral other  common  articles  of  diet  produce  polyneuritis  gallinarum  as 
certainly  as  does  rice.  It  would  therefore  be  quite  as  rational  to  forbid 
the  sale  of  sago,  potatoes,  or  corn  starch,  in  this  country,  as  of  rice. 

There  are  certain  accessory  factors  believed  to  favor  beriberi:  The 
disease  occurs  especially  in  overcrowded  places,  such  as  ships,  jails,  and 
asylums;  during  the  hot  and  moist  seasons;  and  following  exposure  to 
wet.  These  are  to  be  avoided.  Europeans  living  under  good  hygienic 
conditions,  and  enjoying  a  well-balanced  diet,  do  not  contract  the  disease. 


PELLAGRA 

Pellagra  is  included  among  the  diseases  associated  with  food  for 
the  evidence  indicates  that  it  is  caused  by  a  deficient  diet  of  some  sort. 
The  disease  was  long  regarded  as  an  example  of  a^  food  intoxication 
caused  by  some  toxicogenic  saprophyte  growing  in  spoiled  corn.  Some 
investigators  still  look  upon  pellagra  as  an  infection;  and  insects 
{Simulium  and  Stomoxys)  have  been  accused  in  its  transmission. 

PellagTa  usually  runs  a  chronic  course,  with  acute  exacerbations, 
which  usually  occur  in  the  spring  and  fall  of  the  year.  The  disease  some- 
times runs  an  acute  and  rapidly  fatal  course.  The  development  seems 
to  be  more  rapid  and  grave  in  children.  The  "poison,"  whatever  its 
nature,  produces  toxic  and  trophic  manifestations.  The  triad  of  symp- 
toms are:  (1)  digestive  disturbances,  (2)  erythema,  and  (3)  nervous 
disturbances.  The  final  scene  usually  includes  profound  cachexia,  great 
muscular  weakness,  and  insanity. 

Pellagra  is  a  preventable  disease  in  which  the  social  conditions  loom 

^Amer.  Jour.  Trop.  Dis.  and  Preventive  Med.,  Aug.  13,  I,  2,  p.  129. 


654  PLANT  FOODS 

large;  it  is  especially  prevalent  where  faulty  diet  combined  with  pov- 
erty, overcrowding,  and  misery  prevail.  It  occurs  both  sporadically  and 
endemically. 

The  disease  was  first  recognized  in  America  in  1804  l)y  Dr.  Oray, 
of  Utica,  New  York,  and  by  Dr.  Tyler,  of  Somerville,  Mass.,  who 
each  reported  a  case  of  probable  pellagra.  It  was  overlooked  until 
190G-1907,  when  Searcy  reported  an  epidemic  in  the  Alabama  Insane 
Asylum.  In  the  same  year  (1907)  Babcock's  article  on  the  cases  in  the 
State  Insane  Asylum  of  Columbia,  South  Carolina,  aroused  our  present 
revival  of  interest  in  the  disease.  In  1908  Wood  and  Lavender  found 
four  cases  in  Wilmington,  North  Carolina.  Since  then  a  flood  of  cases 
have  come  to  light  all  over  the  country,  especially  in  the  south;  out- 
breaks, however,  occur  as  far  north  as  Peoria,  Illinois,  where  40  to  50 
well-marked  cases  out  of  2,200  inmates  were  discovered  in  the  State  Hos- 
pital for  the  Insane.  Lavender  now  estimates  that  there  are  between 
25,000  and  50,000  pellagrins  in  the  United  States. 

The  disease  appeared  in  Italy  about  1750,  but  was  first  described 
there  in  1771  by  Frapolli,  of  Milan,  who  applied  the  name  "pellagra" 
(Italian  pelle,  skin,  and  agra,  rough).  Marzari  in  1810  first  called 
attention  to  the  relation  between  maize  and  pellagra.  In  1844  Balar- 
dini  first  suggested  the  theory  that  the  disease  might  be  due  to  spoiled 
maize,  that  is,  maize  which  had  undergone  fermentative  change  by 
reason  of  the  growth  of  fungi  on  the  grain.  At  present  pellagra  is 
most  prevalent  in  northern  and  central  Italy  and  in  Eoumania.  Triller 
states  that  in  1906  there  were  30,000  pellagrins  in  Eoumania;  in  cer- 
tain parts  of  Italy  as  much  as  30  to  50  per  cent,  of  the  population  have 
the  disease;  in  1899  there  were  nearly  73,000  sick  with  the  disease  in 
all  Italy,  this  being  upward  of  10  per  thousand  of  the  rural  population. 
The  disease  also  occurs  in  Spain,  Corfu,  Asia  Minor,  Austria,  Servia 
Bulgaria,  and  occasionally  in  India,  Africa,  Barbados,  Mexico,  South 
America,  and  Egypt. 

As  preventive  measures  must  be  based  entirely  upon  our  conception 
of  the  etiology  of  the  disease,  it  is  necessary  to  consider  briefly  some 
of  the  views  upon  this  subject.  Until  recently  most  students  of  the  disease 
considered  pellagra  to  be  an  intoxication  due  to  using  Indian  corn 
(maize)  as  a  food,  which,  under  the  influence  of  some  parasitic  growth 
(bacteria  or  fungus),  has  undergone  certain  changes  with  a  production 
of  one  or  more  toxic  substances.  Lombroso,  who  studied  this  subject 
for  years,  made  alcoholic  and  watery  extracts  from  spoiled  maize  and 
obtained  chemical  substances  of  an  undetermined  nature,  which  were 
given  to  men  and  animals  with  the  production  of  symptoms  analogous 
to  pellagra.  This  work  has  not  been  confirmed  and  furthermore  Lom- 
broso's  interpretation  is  doubtful. 

With  regard  to  the  parasites  found  on  maize,  it  may  be  said  that 


PELLAGRA  655 

the  varieties  are  numerous,  and  no  single  one  seems  to  be  constant  enough 
to  be  rated  as  the  definite  causative  agent.  Seni  incriminates  the  Asper- 
gillus  fumigatus  as  the  cause  of  the  maniacal  form  of  pellagra,  and  the 
Aspergillus  favescens  as  the  cause  of  the  depressive  form.  These  molds 
have  resisting  spores  which  withstand  heat,  hence  ordinary  cooking  is 
not  sufficient  to  destroy  them.  The  Bacterium  maydis  has  also  been  asso- 
ciated with  the  disease.  Lombroso,  as  a  result  of  his  studies,  maintained 
that  pellagra  is  due  to  a  poison  (toxine)  developed  in  maize  by  micro- 
organisms (molds  or  bacteria),  in  themselves  harmless  to  man,  that  is, 
saprophytes. 

Other  views  concerning  the  nature  of  pellagra  are :  that  it  is  an  auto- 
intoxication, the  poisonous  substances  being  produced  in  the  bowels  as  a 
result  of  the  constant  and  almost  exclusive  diet  of  corn,  which  produces 
certain  changes  in  the  intestinal  flora,  and  the  production  of  poisonous 
substances.  A  somewhat  similar  view  is  that  the  disease  is  an  intestinal 
mycosis,  the  offending  microorganisms  being  eaten  with  corn  and  coloniz- 
ing in  the  intestinal  tract.  Others  regard  the  disease  as  of  an  infectious 
nature,  and  several  parasites  have  been  reported  in  the  blood  and  organs. 
In  France  especially  the  idea  has  been  brought  forward  that  pellagra  is 
not  a  definite  morbid  entity  at  all,  but  a  symptom-complex  sometimes 
observed  in  alcoholics  and  cachectic  states  of  diverse  origin,  the  erythema 
being  regarded  only  as  a  common  solar  erythema.  Sambon,  as  the  result 
of  epidemiological  studies,  brought  forward  (1905  and  again  recently) 
the  view  that  pellagra  is  an  insect-borne  disease,  and  incriminates  the 
Simulium  reptans. 

Eaubitschek  ^  recently  brings  forward  evidence  that  pellagra  depends 
upon  some  noxious  substance  (noxe)  activated  by  the  action  of  sunlight. 
This  is  the  photodynamic  theory,  and  corresponds  to  the  action  of  light 
upon  a  photographic  negative.  It  is  suggestive  that  the  skin  lesions  in 
pellagra  are  mainly  confined  to  the  exposed  surfaces.  There  is  also  a  sub- 
stance in  buckwheat  poisoning  (fagopyrismus)  that  affects  animals 
exposed  to  the  light,  but  not  those  kept  in  the  dark. 

The  Thompson-McFadden  Pellagra  Commission,  consisting  of  Siler, 
Garrison  and  MacNeal,  believe  that  pellagra  is  a  communicable  infec- 
tion and  is  in  some  way  associated  with  unsanitary  methods  of  sewage 
disposal.  They  found  that  the  immediate  result  of  hygienic  and  dietetic 
treatment  in  adults  have  been  good,  but  after  returning  to  former  condi- 
tions of  enviroment  most  of  the  cases  have  recurred. 

Goldberger  ^  on  the  other  hand  regards  pellagra  a  disease  due  to 
a  dietetic  fault — especially  to  a  deficiency  of  fresh  protein.  Goldberger 
insists  that  pellagra  is  not  a  communicable  disease,  but  that  it  is  essen- 

^  Berliner  klin.  Wochens.,  Vol.   XXIII,  No.   26,  June,   1910. 
''Journal  American  Medical  Association,  February   12,   1916,  LXVI,  p.  471; 
also,  P.  H.  Reports,  October  23,  1914,  November  12,  1915,  October  22,  191.5. 


6r>(;  PLANT  FOODS 

tially  of  dietary  ori<,Mij ;  that  it  is  dependent  on  some  yet  undetermined 
fault  in  diet  in  which  the  animal  and  leguminous  protein  component 
is  disproportionately  small  and  other  non-leguminous  vegetable  com- 
ponents disproportionately  large;  that  pellagra  never  develops  in  those 
consuming  a  mixed,  well-balanced  and  varied  diet. 

Goldberger  produced  pellagra  in  six  out  of  eleven  volunteer  con- 
victs in  a  camp  at  Jackson,  Mississippi,  as  a  result  of  a  one-sided  diet, 
consisting  mainly  of  carbohydrates  (cereals).  The  first  symptoms 
appeared  five  months  after  the  beginning  of  the  restricted  diet,  and 
consisted  of  the  typical  dermatitis,  with  nervous  and  gastric  symptoms. 
None  of  the  controls  became  pellagrous.  Still  more  striking  is  the 
evidence  obtained  by  Goldberger  in  preventing  the  recurrence  of 
pellagra  in  orphan  asylums  in  the  south  by  introducing  a  varied  and 
better  balanced  diet;  all  other  conditions  remaining  the  same.  Further- 
more, a  number  of  clinicians  report  that  pellagra,  if  not  too  far 
advanced,  may  be  cured  upon  the  assumption  that  it  produced  through 
dietary  faults.  It  is  scarcely  necessary  to  look  further  for  the  cause  of 
a  disease  that  may  be  produced  by  a  restricted  diet,  prevented  and  cured 
by  a  balanced  diet.  I  believe  Goldberger  has  proved  his  case  and  that 
his  work  stands  as  one  of  the  achievements  in  preventive  medicine. 

Pellagra,  beriberi  and  scurvy  are  evidently  closely  allied  diseases. 

Com. — Whether  corn  is  directly  or  indirectly  concerned  in  causing 
pellagra,  the  fact  remains  that  it  constitutes  a  large  portion  of  the  faulty 
dietary  of  many  persons  who  develop  the  disease.  A  consideration  of 
this  important  grain  is  here  given  on  account  of  its  public-health 
importance. 

Maize  or  Indian  corn  is  a  native  of  the  Western  Hemisphere  and  was 
cultivated  by  most  of  the  northern  and  western  tribes  of  North  Ameri- 
can Indians  before  Columbus  reached  these  shores.  The  importance  of 
the  corn  crop  to-day  may  be  gathered  from  the  fact  that,  according  to 
the  census  of  1900,  almost  one-third  of  all  the  land  under  cultivation  in 
the  United  States  was  devoted  to  corn.  It  was  grown  on  88.6  per  cent, 
of  all  the  farms  in  the  country  in  the  crop  for  1889.  The  value  of  the 
annual  crop  now  exceeds  a  billion  dollars.  Corn  contains  24.7  per  cent, 
of  water.  The  water-free  material  consists  of  12.7  per  cent,  proteins, 
4.3  per  cent,  fat,  79.3  per  cent,  starch,  sugar,  etc.,  2  per  cent,  crude  fiber, 
and  1.7  per  cent,  of  mineral  matters.  The  several  nutrient  substances 
in  corn  and  other  common  cereals  are  much  the  same ;  the  individual 
compounds,  however,  making  up  these  groups  differ  considerably. 

The  kernel  (see  Fig.  80)  or  seed,  it  must  be  remembered,  is  not 
inert,  but  a  living  thing  which,  under  favorable  conditions,  will  develop 
into  a  new  plant,  and  each  part  of  it  is  made  up  of  cells  especially  fitted 
for  a  particular  role  in  this  process  of  reproduction.  Eoughly  speaking, 
a  seed  consists  of  three  divisions :  the  skin,  the  germ,  and  the  endosperm. 


PELLAGKA  657 

It  is  a  well-known  fact  that  corn,  when  allowed  to  ripen  before  it  is 
taken  from  the  stalk,  keeps  much  better  than  immature  corn.  It  is 
certain  that  protective  substances  (antibodies)  are  developed  in  the 
kernel  which  retard  the  growth  of  bacteria  and  molds.  Moist  corn 
kept  warm  spoils  readily,  whereas  corn  once  thoroughly  dried  is  proof 
against  serious  fermentative  changes. 

The  fact  that  pellagra  is  prevalent  in  our  Southern  States  has  been 
attributed  to  the  fact  that  during  the  past  decade  or  two  the  corn  belt 
has  gradually  been  pushed  farther  and  farther  north.  This  means  that 
it  is  often  harvested  before  it  is  mature,  and  the  chances  of  its  spoiling 
are  favored  in  transporting  it  to  our  southland  in  a  moist  condition.  A 
carload  of  corn  starting  from  the  Great  Lakes  may  ferment  and  become 
so  overheated  on  its  journey  south  that  occasionally  it  catches  fire  spon- 
taneously. These  facts  have  been  given  to  account  for  the  supposed 
increase  in  pellagra  in  our  southern  cities. 

The  tests  for  spoiled  corn  are  not  entirely  satisfactory.  They  may  he 
divided  into  physical,  biological,  and  chemical  tests.  The  physical  test 
consists  mainly  in  the  luster,  the  absence  of  molds,  the  odor,  and  the 
taste.  The  biological  test  consists  in  planting  the  corn;  from  90  to  95 
per  cent,  should  germinate.  The  chemical  test  includes  among  other 
determinations  the  proportion  of  ash  after  burning,  and  Gosio's 
phenolic  reaction  with  ferric  chlorid.  A  green  purple  color  with 
this  reagent  indicates  fermentation,  with  the  production  of  phenolic 
compounds. 

Spoiled  corn  may  be  renovated  by  polishing  and  then  heating,  to 
prevent  further  growth  of  molds.  It  is  difficult  to  detect  renovated 
corn  by  inspection  alone,  but  the  biological  test  will  disclose  whether 
or  not  it  has  been  heated.  The  practice  of  renovating  corn  should 
either  be  prohibited  or  be  placed  under  strict  official  control. 

Prevention  of  Pellagra. — The  line  along  which  pellagra  prophylaxis 
is  planned  depends  entirely  upon  our  conception  of  the  disease.  As 
pellagra  prevails  especially  among  the  poor,  but  particularly  the  igno- 
rant with  defective  dietaries,  it  at  once  becomes  evident  that  economic 
and  social  improvements  are  an  important  part  of  the  program. 
Prophylaxis  spells  prosperity  in  this  disease  as  in  others. 

In  accordance  with  Goldberger's  views  pellagra  may  be  prevented 
and  even  eradicated  by  substituting  a  mixed,  well-balanced,  varied  diet 
for  the  restricted,  one-sided  diet  so  common  in  pellagrous  communities. 
Emphasis  should  be  laid  upon  a  larger  proportion  of  animal  and  legumi- 
nous protein,  such  as  fresh  lean  meat,  fresh  milk,  eggs,  beans  and  peas, 
fresh  or  dried  but  not  canned,  and  of  even  greater  importance  a  proper 
balance  to  the  diet.  It  is  probable  that  the  substituting  of  the  common 
dried  legumes  into  the  winter  dietary  of  our  southland  would  at  least 
prevent  the  spring  crop  following  the  restricted  winter  diet. 


658  PLANT  FOODS 

The  Italian  struggle  culminated  in  the  law  of  ]902  for  "the  pre- 
vention and  cure  of  pellagra,"  which  was  inspired  by  Lombroso's  views 
upon  the  disease.  The  Italian  measures  may  be  summarized  as  follows: 
those  aimed  at  the  cure  of  the  disease  are  a  free  distribution  of  salt  (a 
government  monopoly  in  Italy),  the  distribution  of  food  either  at  the 
homes  of  the  patients  or  through  sanitary  stations,  and  the  treatment 
of  severe  cases  in  hospitals  for  pellagrins  and  in  insane  asylums.  The 
prophylactic  measures  are  mainly  directed  against  the  use  of  spoiled 
corn  as  an  article  of  food.  They  comprise  a  census  of  the  disease  and 
a  report  of  all  cases;  the  testing  of  corn  and  meal  brought  in  at  the 
frontiers  or  offered  for  sale  to  the  mills  and  the  prohibition  of  its  sale 
if  found  spoiled ;  the  exchange  of  good  corn  for  spoiled  corn ;  desiccating 
plants ;  cheap  cooperative  kitchens ;  the  improvement  of  agriculture ;  and 
the  education  of  the  people.  The  corn  is  inspected  by  experts  and  is 
submitted  to  certain  tests.  If  found  spoiled,  its  sale  for  food  is  pro- 
hibited. The  tests  are  not  entirely  satisfactory  from  a  scientific  stand- 
point, but  seem  sufficient  for  practical  purposes.  According  to  Mr.  Cut- 
ting, the  weak  point  in  the  inspection  of  corn  seems  to  be  in  dealing 
with  home-grown  corn,  especially  the  meal,  either  at  the  mills  or  on  the 
markets.  There  seems  to  be  no  solution  of  this  difficulty  except  govern- 
mental ownership  of  the  mills.  The  agricultural  improvements  are  di- 
rected toward  teaching  the  use  of  better  varieties  of  corn  and  proper 
methods  of  culture,  handling,  etc.,  or  how  to  supplant  corn  entirely  with 
a  more  profitable  crop. 

The  desiccating  plants  for  the  artificial  drying  of  corn  are  considered 
a  very  important  prophylactic  measure,  as  they  prevent  the  spoiling  of 
the  grain.  These  desiccators  are  of  two  types,  fixed  and  portable,  and 
there  are  a  large  number  of  public  desiccators  throughout  Italy.  There 
is  also  a  provision  in  the  law  for  public  storehouses  properly  constructed, 
where  the  grain  may  be  stored  under  the  best  conditions  to  prevent  spoil- 
ing. Eural  bakeries  and  economic  kitchens  are  establishments  where 
an  effort  is  made  to  eliminate  from  the  peasant's  diet  bread  made  of 
corn,  by  supplying  good  white  bread  and  other  food  at  a  low  cost.  Above 
all,  however,  stands  the  education  of  the  people  to  the  dangers  of  spoiled 
corn,  and  the  healthfulness  of  a  varied  diet  and  better  living  conditions. 

The  supposition  that  the  ingestion  of  good  or  spoiled  maize  is  an 
essential  cause  of  pellagra  is  not  supported  by  the  studies  of  the  Thomp- 
son-McFadden  Pellagra  Commission.^  They  believe  that  pellagra  is,  in 
all  probability,  a  specific  infectious  disease  communicable  from  person 
to  person  by  means  at  present  unknown.  The  Commission  discovered 
no  evidence  incriminating  fiies  of  the  genus  Simuliuvi,  and  state  that  if 

*Siler,  J.  F.,  Garrison,  P.  E.,  and  MacNeal,  W.  J.:  "Pellagra.  A  Summary 
of  the  First  Progress  Report  of  the  Thompson-McFadden  Pellagra  Commission." 
J.  A.  M.  A.,  Jan.  3,  1914,  LXII,   1,  p.  8. 


REFEEENCES  659 

pellagra  is  distributed  by  a  blood-sucking  insect,  Stomoxys  calcitrans 
would  appear  to  be  the  most  probable  carrier.  The  Commission  is  in- 
clined to  regard  intimate  association  in  the  household,  and  the  con- 
tamination of  food  with  the  excretions  of  pellagrins  as  possible  modes 
of  distribution  of  the  disease. 

In  my  opinion,  Goldberger's  views  of  pellagra  are  correct.  The 
disease  may  be  prevented,  produced,  and  even  cured,  if  not  too  far 
advanced,  in  accordance  with  the  view  that  it  is  caused  by  a  faulty 
dietary.  Before  pellagra  is  eradicated,  it  will  mean  general  education 
concerning  balanced  diets  and  general  prosperity  sufficient  to  purchase 
the  necessary  articles  making  up  such  a  diet. 


REFERENCES 

Wiley :     "Foods  and  Their  Adulteration."    2nd  Ed.,  Philadelphia,  1911. 

Thompson:     "Practical  Dietetics."     New  York,  1909. 

Richards  and  Woodman :  "Air,  Water,  and  Food  from  a  Sanitary 
Standpoint."     3rd  Ed.     New  York,  1911. 

Leach :     "Food  Inspection  and  Analysis."     New  York,  1907. 

Parry:     "The  Analysis  of  Food  and  Drugs."     London,  1911. 

Tibbies:  "Foods:  Their  Origin,  Composition  and  Manufacture."  Chi- 
cago, Med.  Book  Co.,  1912. 

Greenish:  "Microscopical  Examination  of  Foods  and  Drugs."  Philadel- 
phia, 1910. 


SECTION   IV 
AIR 

CHAPTEE   I 
COMPOSITION  OF   THE  AIR 

The  air  constitutes  a  gaseous  ocean  in  which  we  live;  it  consists  of 
a  vast  volume  of  gases  at  least  one  hundred  miles  high.^  Ordinarily  we 
speak  of  this  gaseous  envelope  of  the  earth  as  the  atmosphere,  and  the 
water  resting  upon  the  surface  of  the  earth  as  the  aquasphere,  while  the 
solid  structure  of  the  earth  is  called  the  petrosphere.  Between  the 
atmosphere  on  one  hand  and  the  petrosphere  and  aquasphere  on  the  other 
hand  is  the  region  of  most  abundant  life,  and  this  is  spoken  of  as  the 
vivosphere. 

The  importance  of  fresh  air  was  almost  completely  ignored  in  prac- 
tical life  until  recently — thanks  to  the  tuberculosis  propaganda.  While 
recent  studies  have  shown  that  the  air  is  not  to  be  feared  as  a  frequent 
medium  for  conveying  specific  infections,  it  has  been  demonstrated  that 
an  abundant  supply  of  fresh  air  is  necessary  to  perfect  well-being.  Sta- 
tistical studies  seem  to  prove  that,  of  the  predisposing  causes  of  sick- 
ness which  are  usually  in  action,  impurities  of  the  air  are  perhaps  the 
most  important.  This  has  been  stated  over  and  over  again  in  the  case 
of  horses,  cattle,  and  dogs,  as  well  as  in  men  confined  in  badly  ventilated 
barracks,  jails,  and  other  places. 

Many  other  factors  are  now  known  to  be  a  greater  menace  to  health 
than  the  "bad"  air  of  crowded  places;  sanitarians,  however,  have  come 
to  regard  an  abundant  supply  of  pure  fresh  air,  well  conditioned,  as 
one  of  the  real  essentials  for  health  and  maximum  efficiency.  Many 
of  the  ill  effects  attributed  to  bad  air  are  really  due  to  crowding.  Crowd- 
ing forces  the  occupants  into  close  personal  contact  and  thus  favors 
the  spread  of  infections.  It  is  a  well  recognized  principle  in  military 
hygiene  that  in  a  crowded  barracks,  with  good  or  bad  air,  there  will  be 
an  excessive  amount  of  pneumonia,  sore  throats,  colds  and  other  inflam- 
matory affections  of  the  upper  respiratory  passages — which  at  times 
become  epidemic. 

*  Forty-five  or  fifty  miles  is  its  practical  limit,  and  anything  beyond  that 
distance  is  in  an  extremely  tenuous  state. 

661 


662  COMrOSITJO.N   OF  THE  AIll 

While  fresh  air  is  so  necessary  to  perfect  well-being,  nevertheless 
some  people  get  along  with  surprisingly  litlle,  and  that  offen  vitiated. 
Many  people  sleep  huddled  up,  with  their  faces  completely  covered  as 
though  they  would  suffocate.  In  Holland  many  people  sleep  in  an  ar- 
rangement not  unlike  a  closet,  and  yet  retain  rugged  health.  Dogs, 
sheep,  and  animals  sleep  huddled  up,  with  their  faces  completely  cov- 
ered, sometimes  in  caves  or  dens  where  the  air  must  he  very  bad.  It  is 
evident  that  the  factor  of  safety  must  be  very  large,  also  that  the  ques- 
tion of  habit  plays  a  conspicuous  role,  for  persons  accustomed  to  good 
fresh  air  are  rendered  truly  miserable  when  confined  to  a  close,  stuffy 
room. 

The  two  chief  functions  of  the  air  that  are  especially  concerned  with 
health  are  (1)  interchange  of  gases  in  respiration  and  (2)  regulation  of 
bodily  temperature.  Further,  it  should  be  remembered  that  the  com- 
bustion of  the  food  we  eat  depends  upon  the  oxygen  of  the  air  we  breathe, 
and-  that  digestion  ani  metabolism  are  stimulated  and  improved  by  an 
abundant  supply  of  fresh  air  or  rendered  sluggish  and  retarded  by  pro- 
longed exposure  to  vitiated  air. 

The  atmosphere  is  now  known  to  contain  the  following  gases  in  the 
following  approximate  proportions  measured  at  0°  C.  and  at  760  mm. 
pressure : 

Volumes       Weight 
Per  Cent.    Per  Cent. 

Oxygen 20.94  23.2 

Nitrogen. 78.09  76.9 

Carbon  dioxid 0 .  03 

Argon 0 .  94 

Helium,  krypton,  neon,  xenon,  hydrogen, 

hydrogen  peroxid,  ammonia,  ozone traces 

"Pure"  air,  in  addition,  contains  M'ater  vapor  in  varying  amounts, 
dust,  radioactive  substances,  etc. 

The  air  is  a  mixture  of  gases  and  not  a  chemical  compound.  The 
proofs  of  this  are  manifold:  (1)  the  gases  do  not  exist  in  the  air  in 
the  proportion  of  their  combining  weights  or  any  multiple  of  them ; 
(2)  on  mixing  the  gases  in  atmospheric  proportions  there  is  no  heat 
evolved;  (3)  the  composition  of  air  within  limits  is  variable;  (4)  when 
water  dissolves  air  it  dissolves  each  gas  according  to  its  partial  pres- 
sure and  its  own  proper  coefficient  of  solubility.  Thus,  air  contains 
more  nitrogen  than  oxygen,  but,  oxygen  being  more  soluble,  water  takes 
up  1.87  parts  of  oxygen  to  1  part  of  nitrogen. 

Jean  Mayow  in  1669  first  proved  that  air  was  not  an  element,  but  a 
mixture  of  gases,  and  later  Lavoisier  discovered  the  two  gases  which 
about  100  years  afterwards  were  separated  by  Priestley  and  Sheele. 

The  composition  of  the  air  shows  wonderful  uniformity  all  over  the 
earth's  surface  wherever  examined.    This  is  due  to  the  enormous  amount 


OXYGEN  663 

of  atmosphere  and  the  mixing  influences  of  air  currents.  However,  in 
confined  spaces  where  the  air  is  not  in  motion,  especially  where  decom- 
position of  organic  matter  is  taking  place  or  where  active  combustion  is 
going  on,  or  in  the  presence  of  animal  life,  the  composition  of  the  air 
varies  considerably. 

The  difference  in  composition  between  inspired  and  expired  air  is  as 
follows : 

0  N  CO2 

Inspired  air 20.81  79 .  15  .03 

Expired  air 16.033        79.557        4.38 

The  expired  air  is  also  warmer,  is  increased  in  volume,  and  contains 
more  moisture,  but  fewer  particles,  such  as  dust  and  bacteria.  Under 
normal  conditions  of  quiet  respiration  the  expired  breath  contains  no 
bacteria. 

OXYGEN 

About  one-fifth  (20.94  per  cent,  by  volume,  23.2  per  cent,  by  weight) 
of  the  atmosphere  consists  of  oxygen,  which  in  many  respects  is  its 
most  important  element.  Slight  differences  are  noted;  thus,  the  air  of 
towns"  contains  somewhat  less  (20.87  per  cent,  by  volume)  than  in  mid- 
ocean.  The  slight  differences  that  have  been  noted  in  the  percentage  of 
oxygen  are  of  no  special  importance.  It  may  drop  to  17  per  cent,  or 
may  rise  to  50  per  cent,  or  even  higher  without  any  very  apparent  altera- 
tion in  the  vital  functions.  An  atmosphere  containing  only  11  to  12  per 
cent,  of  oxygen  becomes  dangerous,  and  7.2  per  cent,  results  in  death. 

The  amount  of  oxygen  absorbed  depends  rather  upon  the  needs  of 
the  body  than  upon  the  amount  in  the  air.  About  5  per  cent,  of  the 
oxygen  in  the  air  is  removed  by  respiration. 

Alveolar  air  normally  contains  about  16  per  cent,  of  oxygen,  and 
the  red  blood  cells,  as  they  leave  the  lungs,  are  practically  saturated  with 
it.  The  amount  taken  up  on  their  next  trip  through  the  lungs  depends 
on  how  much  they  have  given  up  to  the  tissues  in  the  meantime,  not 
upon  how  much  is  available  for  their  use.  The  normal  16  per  cent,  of 
oxygen  in  the  alveolar  air  is  automatically  maintained  by  the  action  of 
the  COo  on  the  respiratory  center,  but  on  account  of  the  chemical  affinity 
of  the  hemoglobin  for  oxygen  the  blood  cells  may  still  take  practically 
their  full  capacity  of  oxygen  when  it  is  reduced  to  12  per  cent,  or  less 
in  the  alveolar  air.  In  other  words,  a  large  excess  of  oxygen  is  con- 
stantly maintained  in  the  air  of  the  lungs.  While  it  is  one  of  the  chief 
functions  of  respiration  to  supply  oxygen  to  the  body,  neither  a  surplus 
nor  a  deficiency  of  it  in  the  air,  unless  the  alteration  is  extreme,  has 
any  effect  on  the  respiratory  movements.  Breathing  will  not  be  lessened 
nor  more  oxygen  taken  up  because  more  of  it  is  supplied  to  the  lungs; 


664  COMPOSITION  OF  THE  AIR 

nor  will  the  oxidation  processes  in  the  body  be  affected  in  any  way,  unless 
other  influences  are  simultaneously  brought  into  play.  Indeed,  Hender- 
son reminds  us  that  it  is  necessary  to  go  only  a  short  distance  up  into 
the  mountains  to  come  under  an  atmospheric  pressure  such  as  to  reduce 
the  oxygen  supply  considerably.  Yet  mountain  air  is  especially  health- 
ful. Except  in  extreme  conditions  the  amount  of  oxygen  in  the  closest 
halls  crowded  with  people  practically  never  falls  below  20  per  cent.  The 
amount  of  oxygen  in  the  air  apparently  has  little  or  nothing  to  do  with 
the  stimulating  or  depressing  properties  of  the  atmosphere  breathed  in 
ordinary  life. 

The  constant  percentage  of  oxygen  is  due  in  part  to  the  enormous 
amount  of  it.  Fliigge  estimates  that  at  the  present  rate  at  which  the 
oxygen  is  used  by  respiration  and  com.bustion  it  would  take  eighteen 
thousand  years  to  reduce  it  by  one  per  cent.,  even  if  not  replaced  by 
vegetation.  The  lungs,  of  course,  at  no  time  after  the  first  breath 
contain  air  with  the  full  percentage  of  oxygen.  This  is  owing  to  the 
fact  that  the  lungs  do  not  completely  empty  themselves,  and  the  resid- 
ual air  remaining  in  the  lungs  accumulates  carbon  dioxid  and  loses 
oxygen. 

Oxygen  is  the  element  in  the  air  that  sustains  all  life.  It  is  ab- 
sorbed by  the  lungs,  passes  into  the  blood,  combines  loosely  with  the 
hemoglobin  of  the  red  blood  corpuscles,  and  is  thus  carried  to  all  the 
tissues  and  cells  of  the  body.  Oxygen  in  combination  with  the  hemo- 
globin forms  an  unstable  compound — oxyhemoglobin — which  gives  the 
bright  red  color  to  arterial  blood.  The  oxygen  bound  with  the  hemo- 
globin in  arterial  blood  consists  of  from  23  to  25  per  cent,  of  the  volume 
of  the  blood.  The  amount  of  oxygen  absorbed  varies  with  the  age,  con- 
dition of  health,  and  activity.  According  to  Professor  Foster,  the  aver- 
age person  inhales  in  24  hours  about  34  pounds  of  air,  which  corre- 
sponds to  a  little  over  7  pounds  of  oxygen.  As  the  lungs  absorb  about 
one-fourth  of  the  oxygen  inhaled,  it  appears  that  the  average  amount 
of  oxygen  absorbed  daily  is  nearly  two  pounds.  Oxygen  also  exists  in 
its  gaseous  form  in  blood,  saliva,  bile,  urine,  and  other  fluids  of  the 
body,  but  only  in  minute  amounts. 

The  amount  of  oxygen  in  the  air  may  readily  be  measured  in  the 
Petterson-Palmquist  or  Haldane  apparatus.  The  oxygen  is  absorbed 
by  10  per  cent,  oxalic  acid  in  a  saturated  solution  of  KOH  (sp.  .gr. 
1.058)  ;  the  difference  in  volume  before  and  after  absorption  represents 
the  amount  of  oxygen  (pp.  591-593). 

Determinations  of  the  amount  of  oxygen  of  the  atmosphere  have 
no  particular  hygienic  significance. 


OZONE  *665 


NITROGEN 


The  nitrogen  in  the  air  may  be  regarded  as  a  diluent,  so  far  as  its 
direct  action  upon  man  is  concerned.  There  is  no  appreciable  differ- 
ence in  the  amount  of  nitrogen  contained  in  inspired  and  expired  air. 
Although  inert,  it  is  very  important,  for  it  serves  to  dilute  the  oxygen 
and  thus  regulate  the  rate  of  combustion  and  its  prototype  respiration. 
The  nitrogen  is  of  more  direct  importance  to  plants,  as  some  are  able 
to  fix  some  of  the  atmospheric  nitrogen  through  the  action  of  certain 
bacteria,  as  B.  radicicola,  in  the  root  nodules.  While  nitrogen  in  the 
atmosphere  seems  to  be  an  indifferent  element  and  has  no  hygienic  sig- 
nificance, it  is  a  constant  constituent  of  all  protein  matter.  The  amount 
of  nitrogen  dissolved  as  a  gas  in  the  blood  and  body  juices  increases  pro- 
portionately with  the  pressure  (P.  Bert). 


ARGON 

Argon,  discovered  in  1894  by  Lord  Eayleigh  and  Professor  Eamsey, 
is  quite  inert  chemically;  that  is,  it  has  not  been  made  to  combine  with 
any  other  element.  It  comprises  from  0.75  to  1  per  cent,  of  the  atmos- 
phere. Argon  has  not  been  demonstrated  in  the  body;  it  is  apparently 
indifferent,  and,  so  far  as  our  present  knowledge  goes,  has  no  hygienic 
significance. 

OZONE 

Ozone,  described  by  Schonbein  in  1840,  is  rarely  found  in  the  air 
in  greater  proportions  than  mere  traces,  but  it  is  so  potent  chemically 
that  even  small  quantities  may  be  of  importance.  At  Montsouris,  after 
years  of  observation,  the  largest  quantity  of  ozone  found  in  outside  air 
was  1  part  in  700,000.  Ozone  may  be  regarded  as  a  normal  constituent, 
though  by  no  means  constant  in  air.  It  is  generally  absent  in  the  air 
of  large  towns  and  cities,  and  almost  never  present  in  the  air  of  in- 
habited rooms.    It  is  most  abundant  at  sea  and  near  woods. 

Atmospheric  ozone  is  formed  in  nature  during  electric  discharges,  by 
the  oxidation  of  phosphorescent  substances;  and  perhaps  by  the  respira- 
tion of  plants;  also  by  friction  of  large  masses  of  water,  such  as  the 
sea  against  the  air. 

Ozone  consists  of  three  atoms  of  oxygen  instead  of  two,  compressed 
into  a  molecule,  thus:  SOa^^SOg.  It  is  one  of  the  most  powerful  oxidiz- 
ing agents  known,  and  in  small  amounts  is  exceedingly  irritating;  in 
large  amounts  it  is  fatal  to  life.    Ozone  is  one  of  our  most  active  bleach- 


666  COM  POSITION  OF  THE  AIR 

ing  agents,  and  in  proper  concentration  is  one  of  the  most  potent  germi- 
cides known,  and  is  used  to  sterilize  water,  to  disinfect  bandages,  and 
for  otlier  purposes. 

It  requires  at  least  13  parts  of  ozone  per  million  in  the  atmosphere 
to  influence  bacteria.  Such  large  proportions  are  never  present  under 
natural  conditions.  Comparatively  small  amounts  are  irritating  to  the 
respiratory  mucous  membrane.  Thus,  Hill  and  Flack  ^  have  studied 
the  action  of  pure  ozone  (free  of  contaminating  oxids  of  nitrogen),  and 
find  it  irritating  in  the  proportion  of  one  part  per  million.  Exposure 
for  two  hours  to  a  concentration  of  15  to  20  parts  per  million  endan- 
gers life.  Hill  and  Flack  conclude  that  there  is  no  harm  in  breath- 
ing weak  concentrations  of  ozone,  such  as  can  scarcely  be  perceived  by 
a  keen  sense  of  smell. 

Bohr  and  Maar  found  that  any  considerable  concentration  (even 
less  than  1  part  per  million)  diminishes  the  oxygen  intake  and  the  car- 
bon dioxid  output.  The  symptoms  produced  by  exposure  to  ozone  in 
addition  to  irritation  of  the  mucosa,  are  headache,  restlessness,  drowsi- 
ness, depression  and  coma. 

Since  ozone  in  concentration  of  one  part  per  million  parts  of  air  is 
certainly  injurious,  and  since  this  amount  of  ozone  will  not  destroy 
odors  nor  kill  bacteria,  nor  purify  organic  matter,  it  has  no  hygienic 
value  and  should  not  be  used  as  a  substitute  for  room  ventilation  or  to 
purify  air  in  offices,  schools,  and  other  occupied  spaces. 

Ohlmiiller  ^  demonstrated  that  ozone  in  considerable  strength  was 
incapable  of  killing  dry  bacteria  within  the  time  limits  of  his  tests. 
Jordan  and  Carlson^  and  also  Konrich  *  found  that  ozone  ranging  from 
3  to  4.6  parts  j)er  million  exerts  no  surely  germicidal  action,  and  that 
the  alleged  effects  of  ozone  on  the  ordinary  air  bacteria,  if  it  occurs  at 
all,  is  slight  and  irregular  even  Avhen  .amounts  of  ozone  far  beyond  the 
limit  of  human  physiologic  tolerance  are  employed. 

Human  beings  are  injuriously  affected  by  amounts  of  ozone  far  less 
than  are  necessary  to  produce  even  a  slight  bactericidal  effect. 
Ozone,  therefore,  has  no  place  in  practical  disinfection  of  occupied 
places. 

The  exaggerated  claims  of  the  deodorizing  properties  of  ozone  are 
not  justified.  Ozone  masks  disagreeable  odors  Avithout  destroying  them. 
In  this  way  ozonizing  machines  can  conceal  faults  in  ventilation  while 
not  correcting  them.     These  conclusions  have  been  reached  by  Jordan 

^Proceed.  Royal  Bociety,  London,  B,   1911,  LXXXIV,  404. 

^  "Ueber  die  Einwirkung  des  Ozone  auf  Bakterien,"  Arh.  a.  d.  k.  Gesundheit- 
samte,  1893,  VIII,  229. 

'Jordan,  E.  O.,  and  Carlson,  A.  J.:  "Ozone:  Its  Bactericidal  Physiologic 
and  Deodorizing  Action,"  J.  A.  M.  A.,  Sept.  27,  1913,  LXI,  No.  13,  Part  1, 
p.  1007. 

*Konrich:  "Zur  Verv^endung  der  Ozona  in  der  Luftung,"  Ztschr.  f.  Uyg.. 
1913,  LXXIII,  443. 


AMMONIA  ^Qt 

and  Carlson,  Erlandsen  and  Schwarz,  Hill  and  Flack,  Konrich,  Sawyer 
and  others. 

Eecently  ozonizers  have  been  placed  upon  the  market  for  the  pur- 
pose of  purifying  the  air  of  rooms;  these  must  not  be  regarded  as  sub- 
stitutes for  ventilation.  Xot  only  may  the  ozone  itself  be  harmful,  but 
the  higher  oxids  of  nitrogen  may  be  formed  when  the  electric  current 
acts  upon  moist  air.  Ozone  is  a  poison  rather  than  a  purifier.^  See 
also  pages  897  and  114C. 

The  tests  for  ozone  depend  upon  the  fact  that  it  oxidizes  the  color 
of  tincture  of  guaiac,  causing  it  to  turn  blue.  It  also  acts  upon  potas- 
sium iodid,  and  turns  starch  a  blue  color  in  presence  of  free  iodin : 
2KI+H20+0=2KOH4-l2. 

Method  for  determining  the  amount  of  ozone  in  air  is  that  recom- 
mended by  Baumert  modified  by  Hill  and  Flack.- 

Ten  liters  of  ozonized  air  are  drawn  through  a  bottle  containing  50 
CO.  of  1  per  cent,  solution  of  potassium  iodid  acidified  by  5  c.c.  of  10 
per  cent,  solution  of  sulphuric  acid ;  1  c.c.  of  1  per  cent,  solution  of 
boiled  starch  added,  and  titrated  with  hyposulphite  solution.  The  hypo- 
sulphite solution  is  made  up  to  contain  0.222  gm.  per  liter,  so  that  1  c.c. 
of  the  solution  represents  1  part  of  ozone  per  million  parts  of  air  when 
10-liter  air  samples  are  used. 


HYDROGEN  PEROXID    (H,0,) 

Hydrogen  peroxid  may  be  found  in  appreciable  traces  in  rain  and 
snow.  One  liter  of  rain  or  snow  water  contains  about  0.182  mg.  of 
hydrogen  peroxid.  This  higher  oxid  gives  many  of  the  reactions  of 
ozone,  being  a  very  active  oxidizing  agent,  and  care  must  be  exercised 
not  to  confuse  them. 

AMMONIA 

The  ammonia  in  the  air  comes  largely  from  the  decomposition  of 
organic  matter.  It  is  produced  in  sufficient  quantities  in  a  manure 
heap  to  be  perceptible  ^o  the  senses.  Ammonia  may  be  regarded  as  one 
of  the  normal  constituents  of  the  atmosphere,  as  it  is  constantly  pres- 
ent in  slight  traces;  it  varies  in  distribution,  more  being  found  in  the 
lower  stratum  of  air  near  the  soil.  It  exists  both  in  the  free  state  and 
also  combined  as  nitrate  and  carbonate.     Daily  analysis  of  the  air  at 

*  Sawyer,  W.  A.,  Beckwith,  Helen  L.,  and  Skolfield,  Esther  M.:  "The  Alleged 
Purification  of  Air  by  the  Ozone  Machine,"  J.  A.  M.  A.,  Sept.  27,  1913,  LXI,  13, 
p.  1013. 

2  Hill  and  Flack:  Proc.  Roy.  Soc,  1911,  LXXXII,  404,=  Jour.  Roy.  Sac. 
Arts,  1912,  LX,  344. 


668  COMPOSITTOX  OF  TTTE  ATR 

the  observatory  at  Moiitsouris  for  five  years  gave,  as  a  mean  for  am- 
monia, 2.2  Tag.  per  100  cu.  m.  There  is  less  after  rain,  because  it  is 
absorbed  by  tlie  water  during  its  passage  through  the  atmosphere. 

Albuminoid  ammonia,  according  to  Angus  Smith,  is  a  measure  of 
the  sewage  of  the  air;  that  is,  the  amount  of  organic  impurities,  both 
living  and  dead. 

MINERAL  ACIDS 

The  atmosphere  at  times  contains  nitric,  sulphuric,  and  other  acids. 
These  are  derived  from  electric  discharges,  but  mainly  from  the  com- 
bustion of  coal  and  from  industrial  j^rocesses.  Sulphuric  acid  or  sul- 
phates in  the  air,  according  to  Angus  Smith,  is  a  measure  of  manu- 
facturing activity  and  also  of  decomposition.  In  other  words,  it  is 
part  of  the  oxidized  and,  therefore,  purified  sewage  of  the  air.  Traces 
of  sulphuric  and  sulphurous  acids  exist  in  the  air.  The  sulphates  and 
sulphites  are  usually  present  as  ammonia  salts.  These  substances  are 
usually  present  in  such  small  amounts  that  they  are  appreciable  only 
when  washed  into  rain  or  snow.  A  liter  of  rain  water  may  contain 
from  0.7  to  2.99  mg.  of  sulphuric  acid.  More  of  this  acid  is  found 
in  the  air  about  industrial  centers  than  in  the  air  over  country  or  sea. 
The  sulphuric  acid  in  the  air  comes  mainly  from  the  sulphur  in  coal. 


CARBON  DIOXID 

Carbon  dioxid  (CO,)  is  a  very  important  constituent  of  the  atmos- 
phere. The  amount  of  this  gas  in  the  air  is  relatively  small — normally 
about  0.03  per  cent.,  usually  expressed  as  3  parts  in  10,000.  When  we 
consider  the  great  bulk  of  the  atmosphere  the  total  amount  of  carbon 
dioxid  is  very  great.  It  is  estimated  that  there  is  more  carbon  in  the 
form  of  carbon  dioxid  in  the  air  than  there  is  in  all  other  forms  on  the 
earth.  Formerly  the  amount  of  carbon  dioxid  in  the  air  was  stated  as  4 
parts  in  10,000,  but  repeated  analyses  with  improved  methods  have 
shown  that  the  correct  amount  is  3  parts  or  slightly  more.^  There  is 
apt  to  be  more  carbon  dioxid  in  the  air  just  above  the  soil  than  at  a 
height  of  8  or  10  feet.  This  is  not  because  the  carbon  dioxid  is  heavy 
and  settles,  but  because  the  soil  air  usually  contains  more  of  this  gas. 
Air  collected  at  great  heights  by  balloons  has  just  the  same  percentage 
of  COg  as  air  at  sea  level.  The  air  over  the  sea  contains  somewhat  less 
than  air  over  the  land.  Carbon  dioxid  in  the  air  comes  from  the  oxida- 
tion   of    organic    matter,    from    respiration,    from    fermentation,    from 

*  Average  of  many  analyses  by  F.  G.  Benedict  is  0.031,  Carnegie  PtibHca- 
tions  No.  166,  1912. 


CARBOX  DIOXID  669 

chemical  action  in  the  soil,  and  from  mineral  springs.  The  exhaled 
breath  contains  about  4.4  per  cent,  of  COg. 

Even  a  small  alteration  in  the  percentage  of  carbon  dioxid,  either 
up  or  down,  would  throw  out  of  adjustment  a  long-established  balance, 
and  this  would  alter  the  climate  of  the  earth  and  might  cause  the  death 
of  all  living  beings.  The  carbon  dioxid  in  the  air  is  the  source  from 
which  green  plants  with  the  assistance  of  sunlight  obtain  their  carbon, 
and  is  thus  indirectly  the  source  of  the  carbon  in  the  bodies  of  animals. 
The  normal  variations  in  the  carbon  dioxid  of  air  in  the  open  are  too 
small  to  be  of  sanitary  importance,  and  it  is  only  when  stagnant  or 
inclosed  air  is  polluted  by  combustion  and  respiration  that  we  find  accu- 
mulations which  may  have  a  bearing  upon  health.  In  narrow  courts 
and  in  smoky  air  the  free  atmosphere  may  contain  0.7  to  0.8  per  cent. 
In  moving  picture  theatres  the  CO,  may  rise  to  43  and  even  72  parts 
in  10,000.  Workshops  may  contain  from  32  to  53  parts  of  carbon 
dioxid  per  10,000,  and  breweries  as  much  as  10  per  cent.  Its  signifi- 
cance varies  with  its  source.  Enormous  volumes  of  carbon  dioxid  are 
constantly  being  poured  into  the  atmosphere.  Manchester  adds  8,000,000 
cubic  meters  of  CO,  a  day  from  the  chimneys  of  industrial  establish- 
ments. Even  then  the  air  of  the  city  averages  only  .0385  per  cent.  COo, 
while  the  air  of  the  country  averages  .0318  per  cent. — a  very  slight  dif- 
ference. It  is  estimated  that  from  all  sources  500,000,000  tons  are  dis- 
charged annually  into  the  atmosphere.  The  reason  that  the  carbon 
dioxid  does  not  accumulate  and  increase  is  that  it  is  constantly  removed, 
especially  by  growing  vegetation.  Plants  absorb  enormous  amounts 
under  the  influence  of  light  and  chlorophyl  to  build  carbohydrates.  It 
has  been  estimated  that  an  acre  of  tree  land  withdraws  in  one  season 
about  41/^  tons  of  COo.  Much  of  the  gas  is  also  absorbed  by  water, 
which  at  ordinary  temperatures  takes  up  its  own  volume. 

The  amount  of  carbon  dioxid  produced  by  respiration  varies  with 
the  vitality,  size,  and  activity  of  the  individual.  During  violent  exer- 
cise almost  ten  times  as  much  carbon  dioxid  may  be  discharged  as  dur- 
ing sleep.  On  the  average  a  man  discharges  about  0.6  of  a  cubic  foot 
of  carbon  dioxid  per  hour  and  a  woman  about  0.4  of  a  cubic  foot.  Dur- 
ing ordinary  activity  a  man  produces,  in  round  numbers,  one  cubic  foot 
per  hour.  An  ordinary  gas  jet  burns  about  6  cubic  feet  of  gas  per  hour 
and  produces  about  3  cubic  feet  of  carbon  dioxid.  Therefore,  so  far  as 
CO2  is  concerned,  a  man  vitiates  the  air  less  than  a  gas  jet. 

The  Amount  and  Function  of  CO2  in  Alveolar  Air. — Haldane  and 
Priestley  ^  have  shown  that  the  regulation  of  breathing  is  dependent  on 
the  concentration  of  CO2  in  the  air  cells  of  the  lungs,  that  is,  the  alveolar 
air.     The  concentration  of  CO2  in  the  arterial  blood  is  determined  by 

^Haldane  and  Priestley:  "The  Regulation  of  the  Lung  Ventilation,"  Jour. 
Physiol.,   1905,  XXXII,  225. 


670  COMPOSITION  OF  THE  AIR 

the  proportion  of  this  gas  in  the  air  cells.  The  nerve  cells  in  the 
respiratory  centers  are  stimulated  by  tlic  C'Oo  in  the  blood. 

The  GOo  which  is  being  constantly  formed  in  the  body  is  carried 
to  the  lungs  by  the  venous  blood.  It  escapes  from  the  blood  into  the 
air  cells  of  the  lungs  and  its  escape  is  impeded  or  accelerated  accord- 
ing to  the  resistance  it  meets  in  them.  This  resistance  depends  on  the 
proportion  of  COg  in  the  alveolar  air,  since  the  tension  of  this  gas  in 
the  blood  can  only  fall  as  low  as  it  is  on  the  other  side  of  the  membrane 
separating  the  blood  stream  from  the  air  cell.  The  arterial  blood  leaves 
the  lungs  with  essentially  the  same  pressure  of  COg  that  is  found  in 
the  alveolar  air.  In  this  way  the  alveolar  CO2  regulates  the  CO2  ten- 
sion in  the  blood  and  so  controls  the  respiratory  movements. 

The  breathing  is  so  regulated  as  to  maintain  the  percentage  of 
COo  in  the  alveolar  air  at  a  pressure  of  about  5  per  cent.  (5.3  to  5.7  per 
cent.)  of  an  atmosphere.  If  the  pressure  falls  below  this,  respiration  is 
lessened  or  stopped  until  the  loss  is  regained.  If  it  goes  above  5  per  cent, 
respiration  is  increased  until  the  normal  is  restored. 

Haldane  and  Douglas  ^  found  that  from  lying  in  bed  to  walking  five 
miles  per  hour  the  CO2  in  the  alveolar  air  was  increased  twelve  times 
and  that  the  alveolar  ventilation  was  likewise  increased  twelve  times, 
so  that  the  percentage  of  CO,  in  the  alveolar  air  remained  practically 
constant.  Henderson  -  found  no  material  change  in  the  composition 
of  the  alveolar  air  on  going  from  rest  to  strenuous  exercise.  The 
increased  production  of  CO2  was  perfectly  compensated  for  by  increased 
breathing. 

There  can  be  no  doubt  that  there  is  a  wide  range  of  physiologic  re- 
sponse on  the  part  of  the  respiratory  function  to  meet  changing  external 
as  well  as  internal  amounts  of  CO..  Thus,  when  more  CO2  is  formed 
in  the  body  the  respiration  is  automatically  increased  in  like  proportion, 
and  in  this  way  the  alveolar  CO2  is  kept  at  a  uniform  level  of  about  5 
per  cent.  The  same  thing  happens  when  we  breathe  an  atmosphere  con- 
taining an  excess  of  CO,.  The  volume  of  air  breathed  is  then  increased 
in  such  a  degree  as,  if  possible,  to  keep  the  CO2  in  the  alveolar  air 
normal.  Haldane  and  Priestley  ^  found  that  with  2  per  cent,  of  CO2  in 
the  inspired  air  the  pulmonary  ventilation  is  increased  50  per  cent.; 
with  3  per  cent,  it  is  increased  about  100  per  cent.;  with  4  per  cent., 
about  300  per  cent. ;  witli  5  per  cent,  about  300  per  cent. ;  and  with  6 
per  cent.,  500  per  cent.  With  the  last  the  alveolar  tension  of  CO2  is, 
of  course,  above  the  normal,  and  this  fact  is  signified  by  severe  pant- 

^  Douglas  and  Haldane :  "The  Dead  Space  of  the  Eespiratory  Passages," 
Jour.  Physiol,  1912,  Abst.  in  Brit.  Med.  Jour,,  Nov.   16,  1912,  p.   1411. 

^Henderson  and  Rnssell:  "A  Simple  Method  for  Determining  the  Carbon 
Dioxide  Content  of  the  Alveolar  Air,"  Am.  Jour.  Physiol.,  1912,  XXIX,  436. 

''Haldane  and  Priestley:  "The  Regulation  of  the  Lung  Ventilation,"  Jour. 
Physiol,   1905,   XXXII,   225. 


CARBON  DIOXID  671 

iug;  but  up  to  3  per  cent,  in  the  inspired  air  the  increase  of  breathing 
is  scarcely  noticed,  unless  muscular  work  is  done,  when  the  increased 
internal  production  of  CO2  calls  for  a  still  greater  increase  of  the  pulmo- 
nary ventilation.  The  adjustments  are  automatic  and  go  on  without  our 
consciousness,  unless  an  excessive  increase  of  breathing  is  demanded. 

Since  even  under  the  most  favorable  conditions  we  cannot  avoid 
drawing  back  into  the  lungs  some  of  the  air  that  has  just  passed  out 
of  them,  not  much  importance  can  be  attached  to  the  slight  variations 
in  CO2  content  which  ordinarily  occur  in  the  air  of  rooms.  (See  page 
743.) 

CO2  as  an  Index  of  Vitiation. — For  years  the  amount  of  COo  in  the 
air  has  been  generally  adopted  as  the  most  convenient  index  of  the  total 
conditions  which  are  usually  prejudicial  to  health  and  comfort.  The 
efficiency  of  ventilation  also  for  years  was  usually  determined  by  an 
estimation  of  COo. 

COo  in  itself  is  not  irritating  or  poisonous.  Large  volumes  may 
be  taken  in  beverages  or  inhaled  without  noticeable  efPeets.  Effects  are 
scarcely  felt  on  the  human  system  when  the  CO2  reaches  2  or  3  per  cent. 
Respirations  increase  with  the  percentage,  both  in  frequency  and  depth, 
until  about  5  per  cent.,  when  there  is  distinct  panting,  and  at  7  or  8 
per  cent,  the  dyspnea  becomes  distressing;  at  10  or  11  per  cent,  head- 
ache, nausea,  and  chilliness  may  be  noted.  Observations  made  by  Pro- 
fessor W.  G.  Anderson  in  my  laboratory  show  that  these  symptoms  are 
more  acute  when  the  carbon  dioxid  is  added  to  the  air  rapidly.  Toler- 
ance or  second  wind  may  be  obtained  in  atmospheres  containing  even 
as  much  as  10  per  cent.  Animals  soon  die  when  the  percentage  reaches 
35  or  45  per  cent,  in  an  artificial  atmosphere.  Man  soon  becomes  uncon- 
scious and  suffocates  in  an  atmosphere  containing  30  per  cent,  of  COo. 

Pettenkoffer  in  1858  proposed  10  volumes  of  CO2  in  10,000  volumes 
of  air  as  the  limit  for  inhabited  rooms.  De  Chaumont  (1875)  found 
that  an  unpleasant  odor  becomes  perceptible  in  air  containing  6  volumes 
of  CO2  in  10,000,  and  fixed  this  as  the  limit,  which  for  many  years 
has  been  accepted  by  sanitarians.  It  was  soon  learned,  however,  that 
the  percentage  of  CO2  may  rise  much  higher  before  ill  effects  become 
perceptible.  Carnelley,  Anderson,  and  Haldane  in  1887  concluded  that 
for  the  very  crowded  elementary  schools  a  lower  limit  than  13  volumes 
was  not  practical.  Haldane  and  Osborn  in  1902  recommended  a  limit 
of  12  volumes  for  factories  and  workshops  at  the  breathing  level,  and 
that  when  gas  or  oil  is  used  for  lighting  the  proportion  should  not  ex- 
ceed 20  volumes.  The  general  consensus  of  opinion  to-day  is  that  10 
volumes  in  10,000  is  well  upon  the  safe  side,  although,  so  far  as  COo 
itself  is  concerned,  more  might  be  permitted  without  fear.  Carbon 
dioxid  is  by  no  means  the  most  mischievous  of  the  constituents  of 
vitiated  air.     It  is  not  merely  a  waste  product.     It  is  one  of  the  irapor- 


672  COMPOSITION  OF  THE  AIR 

tant  hormones  of  the  body.  It  regulates  the  action  of  the  heart,  influ- 
ences the  tonus  of  blood  vessels,  and  stimulates  the  respiratory  center. 

It  is  certainly  erroneous  and  unscientific  to  rely  upon  determinations 
of  COo  in  the  air  of  a  room  as  the  sole  measure  of  its  conditions  for 
respiration.  Carbon  dioxid  never  accumulates  sufficiently  in  any  ordi- 
nary room  to  become  in  itself  serious;  further,  the  amount  of  COo 
in  the  air  of  a  room  gives  no  indication  whatever  of  the  moisture, 
the'  temperature,  or  the  motion  of  the  air  of  that  room.  While  the 
amount  of  CO,,  then,  gives  us  a  rough  index  of  the  degree  of  vitia- 
tion of  the  air,  it  affords  no  information  concerning  its  physical  con- 
ditions, which  are  of  special  importance. 

The  significance  of  carbon  dioxid  upon  health  is  further  discussed 
on  page  670. 

Methods  for  Determining  Carbon  Dioxid. — For  the  ordinary  purposes 
of  a  sanitary  analysis  it  is  not  necessary  to  make  an  accurate  analysis 
of  the  carbon  dioxid  in  air,  such  as  the  chemical  analyist  or  the  student 
of  metabolism  would  make  in  scientific  research.  As  the  carbon  dioxid 
in  itself  is  not  poisonous  and  is  only  an  imperfect  index  of  other  im- 
purities, and  as  its  significance  varies  with  its  source,  sufficient  informa- 
tion may  be  gleaned  for  sanitary  purposes  from  methods  that  give 
results  relatively  comparable. 

The  most  accurate  method  of  determining  CO2  in  the  air  is  that 
described  by  Petterson,  and  used  in  the  Petterson-Palmquist,  the  Sonden 
or  the  Haldane  apparatus.  Both  the  Petterson-Palmquist  and  the  Hal- 
dane  methods  are  convenient,  practical,  and  sufficiently  accurate  for 
all  ordinary  purposes.  The  method  of  Cohen  and  Appleyard  is  reason- 
ably accurate  and  very  convenient.  The  methods  of  Wolpert  and  Fitz 
give  only  rough  estimates. 

Collection  of  Samples. — The  collection  of  the  samples  of  air  to 
be  analyzed  is  fully  as  important  as  the  actual  test.  The  following 
methods  may  be  used: 

The  Water  Siphon  Method. — Two  bottles  (diameter  one-third  the 
height),  volume  about  one-half  liter,  of  nearly  equal  capacity,  should 
be  fitted  with  rubber  stoppers  carrying  small  glass  tubing  connected 
by  several  feet  of  rubber  tubing  with  clamps.  Fill  one  bottle  com- 
pletely with  water,  nearly  free  from  carbon  dioxid. 

The  pair  of  bottles  is  taken  to  the  place  from  which  the  air  is  to 
be  collected.  The  inlet  or  collecting  tube  may  be  long,  so  as  to  reach 
nearly  to  the  ceiling,  or  short;  if  long,  the  first  siphoning  should  be 
rejected  to  insure  filling  the  inlet  tube  with  the  air  desired.  The  stop- 
pers are  then  exchanged  and  the  sample  taken.  The  air-filled  bottle 
should  be  stoppered  and  taken  to  the  laboratory;  or  the  test  solution 
may  at  once  be  added,  and  the  bottle  stoppered  and  shaken,  noting  min- 
utes and  seconds  in  the  Cohen-Appleyard  method.     One  bottle  of  water 


r.VT^P.OX  DIOXID  G73 

with  a  small  reserve  will  serve  for  a  number  of  takings  before  absorbing 
a  sufficient  amount  of  CO2  to  materially  influence  the  results.  If  the 
water  is  acidulated  it  will  take  up  less  COg- 

The  steam  vacuum  method  may  be  used  as  an  alternative  in  less 
accurate  work.  The  bottles  should  be  of  about  150  c.c.  capacity,  made 
for  a  ground-glass  stopper,  but  fitted  with  a  rubber  stopper.  These 
are  filled  with  steam  from  water  first  freed  of  CO,  and  air  by  boiling 
for  5  minutes.  The  bottles  are  inverted  and  a  steam  jet  having  suffi- 
cient pressure  to  throw  the  vaporized  steam  at  least  one  foot  is  allowed 
to  fill  the  bottle  for  3  minutes.  Meanwhile  a  thin  coating  of  vaselin 
is  applied  half  way  up  the  sides  of  the  stopper.  This  not  only  makes 
a  tight  joint,  but  facilitates  removing  the  stopper.  As  soon  as  the 
collecting  bottle  is  removed  from  the  steam  jet  the  stopper  is  instantly 
inserted  and  securely  pushed  in  while  the  bottle  is  still  in  the  inverted 
position.  To  test  the  method  for  completeness  of  vacuum  hold  the 
bottle  in  an  inverted  position  under  water  at  70°  F.  and  remove  the 
stopper. 

Samplers  consisting  of  special  glass  tubes  provided  with  a  glass 
stopcock  at  both  ends  may  be  used  to  collect  samples  of  air,  particularly 
for  the  Sonden,  Petterson-Palmquist,  or  Haldane  apparatus.  These 
samplers  have  a  capacity  of  about  100  c.c. ;  some  of  them  hold  about  200 
c.c.  They  must  be  clean  and  absolutely  dry.  The  samplers  are  filled 
by  means  of  a  bulb  from  a  Davidson  syringe.  Care  must  be  taken  that 
enough  of  the  air  to  be  examined  is  drawn  through  the  sampler  to  force 
out  all  the  original  air  it  contains.  Samples  may  be  collected  in  dupli- 
cate, and  duplicate  analyses  are  always  advisable. 

The  Haldane  Apparatus. — This  apparatus,  shown  in  Fig.  81,  was 
introduced  for  the  determination  of  carbon  dioxid  in  the  case  of  ordi- 
nary rooms,  schools,  factories,  etc.  As  the  apparatus  is  portable,  the 
analysis  can  be  made  directly  on  the  spot  and  the  carrying  to  and  fro 
of  samples  is  thus  avoided,  if  desired.  If  the  buret  is  allowed  to  fill 
while  the  apparatus  is  carried  across  the  room,  a  good  average  sample 
is  obtained.  As  it  takes  some  seconds  for  the  mercury  to  run  down,  this 
method  of  taking  the  sample  can  easily  be  adopted,  or  a  sampler  con- 
taining the  air  to  be  examined  can  be  connected  directly  by  means  of 
rubber  tubing  to  the  g^s  buret.  In  this  ease  it  is  advisable  to  discard  the 
first  filling  of  the  gas  buret  A  in  order  to  get  rid  of  the  air  in  the  rubber 
tubing  and  connections.  About  4  minutes  are  required  for  an  analysis. 
The  accuracy  is  about  1  part  in  10,000. 

The  air  buret  A,  which  is  enclosed  in  a  water  jacket  0,  consists  of 
a  wide,  ungraduated  and  a  very  narrow  graduated  portion.  This  is 
divided  into  100  divisions,  each  of  which  corresponds  to  1  part  in  10,000. 
The  lowest  division  is  marked  0  and  the  numbering  is  upward  from  this 
point.     Any  difference  between  a  reading  at  or  near  zero  and  a  second 


674 


COMPOSTTTOX  OF  THE  ATTJ 


reading  is  thus  shown  by  the  scale  in  volumes  per  10,000,  there  being 
no  calculations  or  corrections. 

The  absorption  pipette  D  is  filled  to  the  mark  E  with  a  20  per  cent. 
solution  of  caustic  potash  through  reservoir  I.  ^J'he  control  tube  G!  en- 
closed in  the  M'ater  jacket  is  used  to  correct  for  variations  in  the  tempera- 
ture of  the  sample  during  the  analysis.     It  is  connected  with  the  potash 


Fig.  81. — Portable  Haldane  Appaeatus  for  Small  Percentages  of  Carbon 

DiOXID. 


pipette  D  by  the  tube  H,  which  has  a  mark  K.  The  pressures  under 
which  the  readings  are  made  are  maintained  constant  by  adjusting  the 
levels  of  the  potash  solution  to  the  marks  E  and  K.  To  compensate  for 
variations  of  temperature  of  the  water  jacket  0,  air  is  blown  through 
the  tube  N,  thus  agitating  the  contained  water. 

The  technic  of  an  analysis  is  summarized  as  follows : 

(1)  Open  the  3-way  cock  B  to  the  air  to  be  examined  and  raise 
the  mercury  bulb  C  to  expel  the  air  in  the  buret  A.  Lower  the  mer- 
cury bulb  and  hang  on  the  adjustable  rack  F  so  that  the  sample  is 
drawn  in  and  the  level  of  the  mercury  falls  to  near  the  zero  mark. 

(2)  Open  the  cock  M  to  the  air  for  a  moment  and  then  turn  it 


CAKBON  DIOXID  675 

so  as  to  connect  the  control  tube  with  the  potash  solution  in  the  tube  H. 

(3)  Turn  the  cock  B  so  as  to  connect  the  sample  with  the  potash 
pipette  D. 

(4)  Squeeze  the  rubber  tube  of  the  potash  reservoir  I  so  as  to 
raise  the  potash  level  about  an  inch  above  the  marks  E  and  K,  and  see 
that  the  level  of  the  potash  alters  sharply  and  about  equally  in  the 
two  tubes. 

(5)  Blow  air  through  the  water  jacket  0. 

(6)  Eaise  or  lower  the  potash  reservoir  I  till  the  potash  is  exactly 
at  the  mark  K  in  the  tube  H. 

(7)  Eaise  or  lower  the  mercury  bulb  C  by  means  of  the  arrange- 
ment F  till  the  potash  is  exactly  at  the  mark  E. 

(8)  Eead  off  the  mercury  level  on  the  scale  of  the  buret  to  0.2 
of  a  division.     (.First  reading.) 

(9)  Eaise  the  mercury  bulb,  so  as  to  drive  the  air  into  the  potash 
pipette  D;  then  lower  it  a  little  and  raise  it  twice  again  so  as  to  wash 
any  carbonic  acid  in  the  connecting  tubing  into  the  pipet. 

(10)  Eeturn  the  air  to  the  buret  A. 

(11)  Again  blow  air  through  the  water  Jacket. 

(12)  Squeeze  the  rubber  tubing  and  adjust  the  two  potash  levels 
at  K  and  E,  as  before,  and  again  read  off  the  mercury  level.  The  first 
reading  subtracted  from  the  second  gives  the  amount  of  COg  in  volumes 
per  10,000. 

(13)  After  the  analysis  open  G  to  the  outside  air  through  cock  M 
and  shut  off  A  and  D  by  turning  cock  B.  This  will  prevent  fouling  of 
the  apparatus  by  the  sucking  up  of  the  potash  solution. 

The  Petterson-Palmquist  Method. — This  is  a  simplified  Sonden 
apparatus  by  which  the  volume  of  CO2  in  the  air  may  be  determined 
directly  in  hundredths  of  a  per  cent,  by  volume.  The  method  is  accu- 
rate to  one  part  in  20,000  of  air,  provided  care  is  taken  with  the  tests. 

The  principle  is  essentially  the  same  as  that  found  in  the  Haldane  or 
the  Sonden  apparatus.  A  measured  amount  of  air  is  collected  in  a  gas 
buret.  This  volume  of  air  is  then  transferred  to  an  Orsat  tube  con- 
taining a  strong  solution  (20  per  cent.)  of  potash,  which  absorbs  the 
COg.  The  air  is  then  returned  to  the  gas  buret  and  remeasured  for 
loss  in  volume.  Great  care  must,  of  course,  be  exercised  that  the  pres- 
sure and  temperature  are  precisely  the  same  before  and  after  absorp- 
tion. The  gas  buret  A,  Fig.  83  is  first  filled  with  mercury  by  raising 
the  reservoir  E.  The  sample  to  be  analyzed  is  then  drawn  into  A  by  low- 
ering E.  There  must  always  be  a  drop  of  water  on  the  surface  of  the 
mercury  and  also  in  the  compensating  cylinder  C.  In  this  way  the 
air  sample  is  kept  saturated  with  moisture.  In  reading  the  volumes 
the  meniscus  of  the  mercury  is  each  time  so  adjusted  that  the  pressure 
in  A  is  exactly  the  same  as  the  pressure  of  the  air  in  the  compensating 


676  COMPOSITION  OF  THE  AIR 

cylinder  C.  This  is  accomplished  through  a  differential  manometer 
containing  a  drop  of  colored  liquid  (petroleum,  in  which  azohenzol  is 
dissolved).     This  manometer  is  connected  by  capillary  glass  tubes  on 


Fig.  82. — Pettehson-Palmquist  Apparatus. 

one  side  with  A  and  on  the  other  side  with  C.  After  the  gas  pipet  A 
is  filled  with  the  sample  of  air  to  be  tested,  close  the  stopcocks  D,  F,  C, 
and  G  and  adjust  the  level  of  the  mercury  in  A,  so  that  the  drop  of  liquid 


CAEBON  DIOXID  67^ 

in  the  manometer  stands  at  zero  on  the  scale.  This  adjustment  is  accom- 
plished through  the  set  screw  E.  In  this  way  the  air  in  A  may  always 
be  brought  to  the  same  pressure  as  that  prevailing  in  the  compensator 
C.  Since  the  air  in  both  compensator  and  pipet  is,  from  the  begin- 
ning of  the  experiment,  separated  from  the  external  atmosphere  by  clos- 
ing the  stopcocks  f,  g,  and  c,  variations  in  the  external  atmosphere 
have  no  effect.  The  temperature  is  regulated  by  filling  the  jar  with 
water  and  keeping  it  agitated,  preferably  with  bujjbles  of  compressed 
air. 

Each  analysis  consists  of  three  operations : 

(1)  The  air  is  drawn  in  from  the  outside  and  is  measured,  the 
level  of  the  mercury  in  the  graduated  tube  being  brought  to  the  zero 
mark.  The  upper  and  narrower  part  of  the  scale,  where  each  division 
denotes  1/10,000  of  the  volume  of  the  pipet,  is  used  in  analysis  of 
atmospheric  air,  or  the  ordinary  air  of  rooms,  where  the  per  cent,  of 
carbon  dioxid  is  at  the  most  not  higher  than  0.1  per  cent.  In  the  analy- 
sis of  very  impure  air  the  lower  part  of  the  graduated  tube  is  used,  each 
division  here  corresponding  to  1/1,000  of  the  whole  volume.  In  meas- 
uring the  volume  the  stopcocks  f,  g,  b,  c,  and  d  must  be  closed. 

(2)  The  stopcocks  d  and  b  are  opened,  a  is  closed,  and  the  air 
is  passed  from  A  to  B.  After  one  or  two  minutes  the  carbon  dioxid 
is  absorbed  and  the  air  may  be  brought  back  into  A;  b  is  then  closed 
and  a  is  opened. 

(3)  The  mercury  level  in  A  is  so  adjusted  that  the  index  again 
fakes  its  normal  position.  The  decrease  in  volume  is  then  read  off  on 
the  scalp. 

Acidulated  water  may  be  used  to  expel  the  air  from  samplers  into 
the  buret  of  the  gas  analysis  apparatus,  if  the  operation  is  quickly 
done.  If  a  refinement  of  accuracy  is  desired  mercury  is  preferable,  for 
even  acidulated  water  will  take  up  some  COg. 

Method  of  Cohen  and  Appleyaed. — This  method  is  based  upon 
the  fact  that,  if  a  dilute  solution  of  lime  water  slightly  colored  with 
phenolphthalein  is  brought  in  contact  with  a  sample  of  air  containing 
more  than  enough  CO2  to  combine  with  all  the  lime  present,  the  solu- 
tion will  gradually  be  decolorized.  The  time  necessary  to  discharge  the 
color  depends  upon  the  amount  of  CO2  present.  The  amount  of  lime 
water  and  the  volume  of  air  being  constant,  the  rate  of  decoloration 
varies  inversely  with  the  amount  of  CO 2. 

Collect  samples  of  air  in  clean,  clear  glass-stoppered  bottles  of  half 
liter  capacity.  The  sample  may  be  collected  by  exhausting  the  air  from 
a  bottle  with  a  pair  of  bellows  or  by  completely  filling  the  bottle  with 
water  and  then  emptying  it  at  the  point  where  the  sample  is  to  be  taken. 
Piun  in  quickly  10  c.c.  of  the  standard  lime  water.  (See  below.)  Ee- 
place  the  stopper;  note  time.      Shake  the  bottle  vigorously  until  the 


678 


COMPOSTTTOX  OF  THE  AIR 


pink  color  disappears;  again  note  time,  and  ascertain  tlie  corresponu- 
ing  amount  of  C()„  from  the  followinar  table: 


Time  in  Minutes  to  De- 
colorize the  Solution 

CO3  per  10,000 

Time  in  Minutes  to  De- 
colorize the  Solution 

CO2  per  10,000 

IH 

114 

16.0 
13.8 
12.8 
12.0 
11.5 
8.6 
7.7 

3^ 

4     

7.0 
5  3 

IH. 

2      

4M 

5     

5.1 

4  3 

2M 

2M 

3M 

5H 

6M 

7^ 

4.4 
4.2 
3.5 

Standard  Lime  Water  for  Testing  CO2. — The  solution  used  is 
a  dilute  solution  of  lime  water  colored  with  pheiiolijhthalein.  To 
freshly  slaked  lime  add  twenty  times  its  weight  of  water  in  a  bot- 
tle of  such  size  that  it  is  not  more  than  two-thirds  full.  Shake 
the  mixture  continuously  for  20  minutes,  and  then  allow  it  to 
settle  over  night  or  until  perfectly  clear.  The  resulting  solution  is  the 
stock  lime  solution,  or  "saturated  lime  water."  If  made  in  the  manner 
indicated,  each  cubic  centimeter  of  it  will  be  very  nearly  equivalent  to 
1  milligram  of  carbon  dioxid. 

If,  however,  it  is  desired  to  knov/  the  strength  of  it  more  ex^  tly, 
it  may  be  determined  by  titrating  with  a  standard  acid. 

To  a  liter  of  distilled  water  add  3.5  c.c.  of  j)henolphthalein  (made  by 
dissolving  0.7  gram  of  phenolphthalein  in  50  c.c.  of  alcohol,  and  adding 
an  equal  volume  of  water).  Stand  the  bottle  of  water  on  a  piece  of 
white  paper  and  add,  drop  by  drop,  saturated  lime  water  till  a  faint  color 
persists  for  a  full  minute.  Kow  add  6.3  c.c.  of  saturated  lime  water, 
quickly  cork  the  bottle,  and  avoid  contact  with  the  COg  of  the  air. 

For  accuracy  in  testing  air  which  is  high  in  carbon  dioxid,  it  is 
found  advantageous  to  use  a  solution  twice  as  strong  as  the  above.  This 
double  solution  is  prepared  in  precisely  the  same  way,  using  5.0  c.c.  of  the 
phenolphthalein  solution  and  12.6  c.c.  of  the  "saturated  lime  water." 

While  this  procedure  does  not  give  an  exact  volume  of  solution,  it  is 
believed  to  be  the  best  for  the  preparation  of  this  dilute  test  solution, 
since  it  obviates  the  necessity  for  pouring  the  prepared  solution  from 
the  measuring-flask  into  the  bottle  in  which  it  is  kept;  12.6  of  the  stock 
lime  solution  is  added  rather  than  10  c.c,  in  order  to  keep  the  values 
obtained  with  the  resulting  solution  more  nearly  comparable  with  the 
older  values  calculated  on  the  supposition  that  10  c.c.  of  "saturated 
lime  water"  was  equivalent  to  12.6  milligrams  of  carbon  dioxid.  (Eich- 
ards  and  Woodman.) 

Methods  of  Wolpert  and  Fitz. — These  are  rough  methods  for 
determining  carl)on  dioxid,  and  while  not  quite  as  accurate  as  the  Cohen 


CARBON  DIOXID 


679 


Mhn 

iiiHlCi 


^ARiHicrACll' 


and  Appleyard  method,  are  useful  because  of  their  simplicity  and  con- 
venience.    The  Wolpert  tester  gives  better  resvilts  than  that  of  Fitz. 

The  volume  of  air  that  must  be  brought  into 
contact  with  a  definite  quantity  of  lime  water  in 
order  to  neutralize  all  the  lime  is  taken  as  a 
measure  of  the  CO,  in  the  air.  The  quantity  of 
lime  water  and  the  time  of  reaction  remaining 
constant,  the  amount  of  CO2  varies  inversely  as 
the  volume  of  air.  The  apparatus  consists  of 
graduated  shakers  (see  illustration),  and  a  pipet 
for  measuring  10  c.c.  of  the  standard  lime  water 
solution.     See  page  678. 

In  using  both  the  Wolpert  and  the  Fitz  ap- 
paratus care  should  be  taken  that  the  finger  used 
to  close  the  end  of  the  tube  is  clean,  since  on  a 
warm  day  the  free  acid  in  the  perspiration  might 
vitiate  the  results.  This  error  may  be  obviated 
by  using  a  rubber  stopper  or  cap. 

The  Wolpert  Air  Tester. — In  using  this 
apparatus  first  remove  the  plunger  and  introduce 
10  c.c.  of  the  standard  lime  water  solution  (see 
page  678)  into  the  graduated  cylinder.  Imme- 
diately insert  the  plunger  and  press  it  to  the 
surface  of  the  lime  water.  Next,  withdraw  the 
plunger  to  the  50  c.c.  mark.  Place  the  finger  or 
rubber  cap  over  the  end  of  the  piston  and  shake 
vigorously  for  30  seconds.  Remove  finger  or 
cap;  press  the  plunger  again  to  the  surface  of 
the  liquid,  withdraw  it  to  the  50  c.c.  mark,  and 
shake,  continuing  this  process  until  the  color  is 
discharged. 

Each  withdrawal  of  the  plunger  admits  40 
c.c.  of  air  to  the  cylinder  and  from  the  total  vol- 
ume of  air  thus  admitted  the  approximate 
amount  of  air  necessary  to  discharge  the  color 
is  determined.  A  more  accurate  estimation  of 
the  amount  of  air  necessary  to  decolorize  the 
lime  solution  can  be  obtained  by  repeating  the 
process  and  admitting  a  smaller  amount  of  air 
to  the  cylinder  the  last  time  the  plunger  is  with- 
drawn.    From  the  total  amount  of  air  used  in 

the  second  test,  the  amount  of  CO2  can  be  determined  from  the  table  on 
the  next  page. 

A  more  convenient  but  less  accurate  method  of  using  this  apparatus 


Fig. 


Ij 


83. — Wolpert    Air 
Tester. 


680 


COMI'USJTIOiNT  OF  THE  AlPt 


Air  in  c.c. 

Usorl 

(.•Ah  per  10,00!) 

Air  in  c.c. 

Used 

C02  por  10,000 

RO 

28 

22 
18 
14 
12 
10 

91 

9 

ne, 

103 

8 

46 

117 

7 

^s 

138 

6 

RQ 

165 

5 

82. 

207 

4 

is  to  put  3  c.c.  of  the  lime  water  into  the  cylinder,  insert  the  plunger  to 
the  line  marked  "extremely  had"  (4  per  cent.)  and  shake  for  one  minute. 
Then  if  the  color  is  not  discharged  withdraw  the  piston  a  little  farther 
and  shake  again,  and  so  on  until  the  position  of  the  plunger,  when  the 
color  is  gone,  can  be  determined.  From  this  the 
percentage  of  CO2  can  be  read  ofE  directly  from  the 
figures  on  the  left  of  the  cylinder. 

FiTZ  Air  Tester. — This  apparatus  con.sists  of 
a  tube  closed  at  one  end,  and  graduated  for  a  dis- 
tance of  20  c.c.  Another  tube  smaller  in  size  and 
open  at  both  ends,  slides  within  the  graduated  tube 
by  means  of  a  rubber  collar.  This  rubber  collar 
should  be  moistened  in  order  that  the  inner  tube 
may  slide  readily. 

Press  the  inner  tube  down  to  the  bottom  of  the 
larger  one  and  measure  into  the  apparatus  10  c.c. 
of  the  standard  lime  water  solution.  (Page  678.) 
Withdraw  the  inner  tube  up  to  the  "tare  mark"  (T) 
which  corresponds  to  the  5  c.c.  mark.  The  bottom 
of  the  inner  tube  serves  as  the  index.    Now  quickly 

,     -}     I        close  the  end  of  the  smaller  tube  with  the  finger; 

^^~  '"•^       hold  the  apparatus  horizontally,  and  shake  it  vigor- 

ously for  30  seconds. 

The  amount  of  air  that  has  thus  been  brought 
in  contact  with  the  solution  is  30  c.c.  Eemove  the 
finger,  again  press  down  the  small  tube  to  the 
bottom  of  the  larger,  and  draw  it  to  the  20  c.c.  mark.  Shake  the  appa- 
ratus again  for  30  seconds.  The  additional  amount  of  air  brought  in 
contact  with  the  solution  is  20  c.c.  Eepeat  the  shaking,  using  20  c.c. 
of  fresh  air  each  time  until  the  pink  color  is  discharged.  A  slight 
trace  of  color  may  be  ignored.  The  amount  of  COo  corresponding  to 
the  total  number  of  c.c.  of  air  used  will  be  found  in  the  above  table. 


Fig.    84. — Fitz    Air 
Tester. 


CHAPTEE  II 
PEESSUEE,  TEMPEEATUEE,  AND  HUMIDITY 

PRESSURE 

Normal  Atmospheric  Pressure. — The  pressure  of  the  atmosphere  at 
sea  level  is  15  pounds  to  the  square  iuch,  or,  as  indicated  in  the  barom- 
eter, it  will  maintain  a  column  of  mercury  30  inches  or  760  millimeters. 
A  man  of  average  size  living  at  sea  level  is  exposed  to  a  total  pressure 
of  about  34,000  pounds — more  than  15  tons.  This  great  pressure  must 
evidently  have  physiological  importance.  All  the  tissues  and  fluids  of 
the  body  are  subjected  to  this  pressure  and  are  in  equilibrium  with  it. 
The  interchange  of  gases  on  which  life  depends  is  largely  a  phenomenon 
of  atmospheric  pressure.  The  pressure  of  the  air  also  keeps  the  heads 
of  the  bones  in  their  sockets  without  muscular  action,  and  doubtless 
performs  other  functions  less  obvious.  The  small  variations  in  pres- 
sure such  as  occur  day  by  day  at  sea  level  have  no  evident  physiological 
effects. 

Diminished  Atmospheric  Pressure. — A  diminution  in  atmospheric 
pressure  is  equivalent  to  breathing  rarefied  or  diluted  air.  The  most 
important  physiological  effects  of  diminished  atmospheric  pressure  are 
due  to  a  diminution  in  the  amount  of  oxygen  absorbed,  hence  the  breath- 
ing is  deeper  and  the  pulse  rate  quickened.  As  the  altitude  increases 
there  is  a  lowered  tension  of  oxygen  in  the  alveolar  air  and  a  diminished 
tension  of  carbon  dioxid.  While  the  rate  of  respiration  may  be  variously 
influenced  in  different  circumstances,  the  depth  of  respiration  is  almost 
invariably  increased.  This  of  itself  not  only  facilitates  the  oxygen 
supply,  but  also  increases  the  elimination  of  carbon  dioxid.  Formerly 
a  great  compensatory  increase  in  the  number  of  red  blood  cells  was  be- 
lieved to  take  place  as  a  result  of  prolonged  residence  in  high  altitudes. 
Thus,  assuming  the'  average  number  of  red  blood  cells  per  cubic  milli- 
meter at  sea  level  to  be  about  5,000,000,  at  Davos  (elevation  1,560 
meters)  the  number  of  red  blood  cells  averages  5,500,000  to  6,500,000. 
At  Cordilleras  (altitude  4,392  meters)  the  average  number  of  red  cor- 
puscles is  8,000,000.  A  similar  change  in  the  blood  has  been  produced 
by  keeping  rabbits  and  guinea-pigs  in  rarefied  air  at  sea  level.  Accord- 
ing to  Biirker,  only  a  comparatively  small  increase  takes  place,  amount- 
ing to  4  or  5  per  cent.,  at  altitudes  of  five  or  six  thousand  feet.     The 

681 


683         PEESSURE,  TEMPERATURE,  AND  HUMIDITY 

same  moderate  results  have  likewise  been  noted  lately  for  much  higher 
altitudes.  The  higher  figures  of  earlier  workers  are  now  accounted  for 
by  the  more  rapid  evaporation  of  blood  samples  at  higher  altitudes,  so 
that  with  improved  teehnic  the  belief  in  the  great  increase  in  the  oxygen- 
carrying  blood  constituents  disappears. 

At  a  height  of  18,000  feet  the  pressure  of  the  atmosphere  is  only 
half  the  pressure  at  sea  level,  thus : 

Height  of 
Altitude  Barometer 

0  foot 30  inches 

910  feet 29  « 

1,850  "  28  « 

2,820  "  27  « 

3,820  «  26  " 

4,850  «  25  « 

5,910  «  24  « 

7,010  «  23  « 

8,150  "  22  « 

9,330  «  21  « 

10,550  «  20  " 

13,170  «  18  « 

16,000  «  16  « 

18,000  «  15  « 

"The  highest  dwelling  place  continuously  occupied  is  the  Observa- 
tory El  Mirti,  in  the  Andes,  at  5,880  m.  The  Observatory  at  Arequipa 
is  at  6,100  m.  Thok  djalung  is  a  village  in  the  Himalayas  at  4,980  m. 
In  Peru,  Bolivia,  and  ISTorthern  Chili  a  very  large  part  of  the  population 
live  above  3,000  m.  Potosi,  which  has  numbered  100,000  inhabitants, 
is  at  4,165  m.,  Cerro  de  Pasco  at  4,350  m.,  the  mines  of  Villacota  at 
5,042  m.,  the  railway  from  Callao  to  Oroya  culminates  in  a  tunnel  at 
4,760  m.,  almost  the  height  of  Mont  Blanc.  An  annual  fair  is  held 
at  Gartok,  at  4,598  m.,  in  the  Himalayas,  to  which  thousands  annually 
come."  ^ 

It  is  evident  that  man  may  become  adapted  to  breathing  a  rarefied 
air  at  great  heights,  which  would  overcome  persons  if  the  change  were 
made  suddenly  from  sea  level.  Linhard  actually  resided,  for  26  days  in 
a  pneumatic  cabinet,  becoming  "acclimated"  gradually  to  a  reduced 
barometric  pressure  of  450  mm.  at  which  he  lived  for  two  weeks. 

The  symptoms  produced  by  a  marked  diminution  in  atmospheric 
pressure  vary  with  circumstances.  The  effects  are  increased  by  cold, 
active  muscular  exertion,  or  improper  clothing.  The  noticeable  symp- 
toms are  increased  rapidity  of  respiration  and  acceleration  of  the  cir- 
culation, noises  in  the  head  and  dizziness,  impairment  of  the  senses  of 
sight,  hearing,  and  touch,  dulness  of  the  intellectual  faculties,  and  a 
strong  desire  to  sleep.  Sudden  changes  to  a  rarefied  atmosphere  cause 
S3mcope,  weakness,  dyspnea,  dizziness,  and  nausea.     These  threatening 

*  Leonard  Hill:     "Recent  Advances  in  Physiology." 


PEESSURE  683 

symptoms  sometimes  go  by  the  name  of  mountain  sickness.  Bert  and 
Journet  believe  this  condition  is  due  to  lack  of  oxygen  and  the  symp- 
toms ma}^,  in  fact,  be  relieved  by  adding  oxygen  to  the  air  inspired. 
Bert  kept  a  bird  alive  in  oxygenated  air,  even  though  the  pressure  was 
reduced  to  less  than  0.1  of  an  atmosphere.  Kronecker  concludes  that 
mountain  sickness  is  caused  by  a  congestion  of  the  lungs,  impeding  the 
flow  of  blood  through  them.  Mosso  and  his  followers  attribute  the 
physical  disturbances  of  a  reduced  atmospheric  pressure  to  the  fact  that 
the  blood  loses  carbon  dioxid  more  quickly  than  it  loses  oxygen,  and 
attributes  mountain  sickness  to  this  decrease  of  carbon  dioxid  in  the 
blood  (acapnia).  Cohnheim  believes  there  is  a  concentration  of  the 
blood  at  high  altitudes;  in  fact,  insignificant  increases  have  been  found 
by  competent  observers.  The  climate  in  high  altitudes  is  always  dry 
and  evaporation  proceeds  rapidly.  As  a  result  individuals  lose  water 
more  readily  than  at  lower  levels.  If  this  explanation  is  tenable,  an  in- 
crease in  corpuscles  and  hemoglobin  content  are  in  no  wise  the  expres- 
sion of  lack  of  oxygen,  but  are  rather  the  outcome  of  the  increased 
evaporation  under  the  altered  conditions  of  climate. 

The  limit  at  which  life  may  be  sustained  is  about  26,000  feet,  at 
which  height  consciousness  is  lost.^  At  this  height  the  barometric  pres- 
sure of  the  air  is  251  mm.,  which  represents  a  pressure  of  oxygen  of  52, 
which  is  the  equivalent  of  6.8  per  cent,  oxygen.  P.  Bert  remained 
20  minutes  in  a  pneumatic  chamber  with  a  pressure  of  only  248  mm. 
without  serious  inconvenience. 

Increased  Atmospheric  Pressure. — While  man  is  often  exposed  to 
rarefied  air,  he  is  seldom  subjected  to  increased  pressure  except  under 
artificial  conditions,  such  as  in  diving  bells,  diving  suits,  and  caissons. 
The  increase  in  atmospheric  pressure  in  the  deepest  mines  has  little 
physiological  significance.  Divers  and  workers  in  caissons  are  not  sub- 
jected to  more  than  about  4^/2  atmospheres,  and  work  under  such  pres- 
sure for  only  a  few  hours  at  a  time.  When  a  diving  bell  is  lowered  10 
meters  into  the  water  the  air  contained  in  it  is  compressed  to  one-half 
its  original  bulk,  and  the  pressure  of  the  air  is  accordingly  doubled.  Each 
10  meters'  depth  means  an  additional  pressure  of  one  atmosphere.  At 
a  depth  of  30  meters,  about  100  feet,  a  diver  is  exposed  to  a  pressure 
of  4  atmospheres  or  about  60  pounds  per  square  inch.  Bert  exposed 
dogs  to  a  pressure  of  10  atmospheres,  and  then  slowly  released  them 
without  harm. 

The  physiological  effects  of  an  increased  atmospheric  pressure  are 
mainly  due  to  an  increase  in  the  amount  of  atmospheric  gases  (espe- 
cially nitrogen)   which  are  taken  up  by  the  blood,  and  also  an  increase 

^The  aviators,  Fleming  and  Steyer,  in  June,  1911,  attained  an  elevation  of 
8,910  meters,  but  experienced  grave  symptoms  which  urgently  called  for  the 
use   of    oxygen    inhalations. 


684         PlIESSUEE,  TEMrEKATUUE,  AND  HUMIDITY 

in  the  chemical  absorption  of  oxygen  by  the  blood.  The  serious  conse- 
quences usually  result  from  too  rapid  decompression.  The  nitrogen  is 
absorbed  by  the  tissues,  especially  by  fat  and  lipoid  tissues  contained  in 
the  nervous  system.  As  the  pressure-  is  released  gas  bubbles  form. 
Hence  corpulent  persons  are  more  liable  to  suffer  than  lean;  those  with 
sluggish  circulation  suffer  most.  Gradual  decompression  gives  a  chance 
for  the  gas  to  escape  from  the  lungs  and  be  expelled  without  the  produc- 
tion of  gas  bubbles. 

Caisson  Disease. — The  effects  produced  by  compressed  air  in  cais- 
sons are:  (1)  those  caused  when  the  men  are  undergoing  pressure,  and 
(2)  during  or  after  decompression. 

The  symptoms  produced  by  an  increase  of  atmospheric  pressure  are 
a  slowing  of  the  respiration,  which  is  evidently  compensatory,  but  on 
account  of  compression  of  intestinal  gases  the  respirations  are  deeper; 
the  pulse  is  slower,  and  evaporation  of  water-vapor  hindered.  The  voice 
may  be  altered;  pains  in  the  ear  are  common,  due  to  pressure  upon  the 
drum,  and  may  be  obviated  by  swallowing  air  and  thus  passing  it  up 
the  Eustachian  tube  into  the  middle  ear.  Sometimes  the  ear  drum  rup- 
tures; headache  and  dizziness  may  also  occur.  During  compression  the 
blood  keeps  absorbing  the  gases  of  the  air  until  the  tension  of  the  gases 
in  the  blood  becomes  equal  to  that  in  the  compressed  air.  As  soon 
as  this  equilibrium  has  been  attained  relief  from  immediate  troubles 
is  secured. 

It  is  during  and  after  decompression  that  the  greatest  danger  to 
health  and  even  risk  of  life  occur.  The  most  frequent  symptom  is 
excruciating  pains  in  the  muscles  and  joints,  called  by  the  workmen 
"bends."  These  pains  may  continue  for  a  few  hours  or  for  two  or 
three  days.  Occasionally  there  is  bleeding  at  the  nose ;  also  severe  abdom- 
inal pain,  and  vomiting,  nausea,  vertigo,  dyspnea,  and  unconsciousness. 
Death  may  result  from  internal  hemorrhage,  or  paralysis  may  ensue — 
the  so-called  diver's  palsy. 

The  effects  of  increased  atmospheric  pressure  and  too  rapid  decom- 
pression were  carefully  studied  by  Paul  Bert  in  1878,  who  showed  that 
the  lesions  are  caused  by  the  escape  of  gases  of  the  atmosphere  which 
have  been  taken  up  in  excessive  amounts,  and  are  released  in  the  blood 
and  tissues  when  the  pressure  is  diminished.  The  blood  vessels  may 
contain  gas  emboli,  which  may  lodge  in  vital  parts  and  cause  sudden 
death,  or  the  delicate  capillaries  may  break,  leading  to  hemorrhage  with 
resulting  paralysis.  Air  emboli  may  be  distressing  or  dangerous  if 
they  occur  in  the  labyrinth  of  the  ear,  in  the  spinal  cord,  in  the  brain, 
or  in  the  heart  or  other  vital  parts. 

The  prevention  of  caisson  disease  consists  in  gradual  decompres- 
sion. Sometimes  the  symptoms  come  on  several  hours  after  the  work- 
man has  left  the  caisson.    As  soon  as  symptoms  come  on  the  workman 


MOVEMENTS  OF  THE  ATMOSPHEEE  685 

should  at  once  be  hurried  back  into  the  compression  chamber  until 
equilibrium  between  the  internal  and  external  pressures  is  restored. 
He  may  then  be  allowed  to  pass  through  the  decompression  chambers, 
but  very  gradually.  A  medical  air-lock  should  be  provided  at  the 
works,  well  heated,  and  furnished  with  bunks  and  emergency  supplies. 

Barometers. — The  pressure  of  the  air  is  measured  by  means  of 
barometers,  the  princii^les  of  construction  and  use  of  which  are  so  well 
known  that  they  do  not  require  special  description. 


MOVEMENTS  OF  THE  ATMOSPHERE 

Moving  air  is  necessary  for  the  maintenance  of  health  and  is  a 
prime  requisite  of  good  ventilation.  The  motion  of  the  air  serves  the 
twofold  purpose  of  bringing  us  a  fresh  supply  and  taking  away  the 
sewage-polluted  air  from  our  immediate  vicinity.  Moving  air  also  favors 
evaporation  and  helps  to  prevent  heat  stagnation  by  keeping  the  tem- 
perature within  normal  limits.  Paul,  Heymann,  and  Erclentz,  in 
Fliigge's  laboratory,  and  also  Leonard  Hill  in  England,  emphasized  the 
importance  of  moving  air  in  assisting  the  heat  regulation  of  our  body. 
They  believe  that  this  is  a  much  more  important  function  of  moving  air 
than  simply  the  bringing  of  fresli  air  or  the  carrying  away  of  the  prod- 
ucts of  respiration.  In  still  air  the  body  soon  becomes  surrounded  by  a 
warm,  moist  aerial  envelope  which  causes  an  overheating  of  the  surface 
of  the  body  and  results  in  the  familiar  symptoms  of  "crowd  poisoning." 
In  a  still  atmosphere  we  are  soon  surrounded  by  a  blanket  of  stagnant 
and  impure  air,  whether  indoors  or  outdoors. 

Much  of  the  benefit  of  mountain,  seaside,  and  other  health  resorts  is 
attributable  to  the  breezes  that  blow  almost  continuously  at  such  places. 
The  health  of  large  cities  located  upon  the  seacoast  or  the  shores  of 
great  lakes  is  favored  by  the  quantities  of  moving  air  with  which  they 
are  frequently  flushed.  A  healthful  climate  is  always  a  breezy  climate 
— within  reasonable  limits.  Much  of  the  benefit  of  driving,  of  fan- 
ning, and  of  rocking-chairs  is  due  to  the  motion  of  the  air  thus  en- 
gendered. 

If  the  air  in  a  poorly  ventilated  room  can  be  kept  in  motion,  say 
with  an  electric  fan,  many  of  the  ill  effects  of  a  vitiated  atmosphere  are 
avoided,  for  the  products  of  respiration  are  diluted,  and  evaporation  and 
heat  interchange  are  favored.  Thus,  Leonard  Hill  placed  eight  stu- 
dents in  a  small  sealed  chamber  which  held  about  three  cubic  meters. 
He  states  that  "at  the  end  of  half  an  hour  they  had  ceased  laughing 
and  joking  and  their  faces  were  congested.  The  carbon  dioxid  had  gone 
up  to  4  or  5  per  cent.  Three  electric  fans  were  then  turned  on,  which 
merely  whirled  the  air  about  Just  as  it  was.     The  effect  was  like  magic; 


G8G         PEESSURE,  TEMPERATTTEE,  AXD  JTUMTDTTY 

the  students  at  once  felt  perfectly  comfortable,  but  immediately  the 
fans  were  stopped  they  again  felt  as  bad  as  before/'  The  relation  of 
moving  air  to  temperature  and  moisture,  with  reference  to  ventilation, 
is  further  discussed  on  page  740. 

In  nature  tKe  atmosphere  is  kept  in  almost  constant  motion  as  a 
result  of  differences  in  temperature.  Thus,  the  hotter  air  in  the  tropics 
rises  and  divides  into  two  currents,  which  flow  toward  the  north  and 
south,  while  heavier,  colder  air  rushes  along  a  lower  level  from  the 
north  and  south  to  take  the  place  of  the  lighter  currents.  The  cold 
currents  from  the  poles  are  known  as  the  trade  winds,  and  the  upper, 
warmer  currents  to  the  poles  as  the  antitrades.  The  upper  currents  to 
the  poles  run  northwest  and  southwest;  while  the  lower  currents  from 
the  poles  run  northeast  and  southeast. 

The  chief  cause  of  periodic  winds,  such  as  daily  sea  breezes  and 
monsoons,  is  the  difference  in  the  heating  of  the  air  above  land  and 
above  sea.  On  a  small  scale  the  same  principle  is  seen  at  play  in 
theaters,  churches,  cathedrals,  and  public  buildings.  The  great  mass  of 
people  crowded  together  heats  the  air  about  them  and  it  ascends;  cool 
air  rushes  in  from  the  aisles  to  take  its  place,  hence  the  almost  unavoid- 
able drafts  in  such  places. 

The  velocity  of  air  currents  is  customarily  measured  by  means  of 
recording  anemometers.  These  instruments  require  a  considerable  veloc- 
ity of  air  and  should  never  be  used  without  a  carefully  prepared  table 
of  corrections  whereby  their  readings  may  be  adjusted. 

It  often  becomes  desirable  in  sanitary  investigations,  particularly 
in  studies  of  ventilation,  to  determine  the  strength  and  direction  of 
currents  of  air  which  are  too  delicate  to  be  measured  by  means  of 
anemometers.  Lighted  candles  will  show  the  direction  of  slight  air 
currents,  the  flame  being  deflected  in  the  direction  in  which  the  cur- 
rent is  moving.  More  delicate  than  this  is  the  method  of  noting  the 
course  taken  by  smoke  from  a  joss-stick,  cigarette,  or  cigar.^ 

When  a  current  of  air  at  the  temperature  of  55"  to  60°  F.  moves  at 
a  rate  of  one  mile  per  hour,  there  is  no  perceptible  draft.  The  rate  of 
mo\ement  in  relation  to  our  perception  is  as  follows: 

Air  moving  at  1.5  feet  per  second — 1.0  mile    an  hour — imperceptible. 
Air  moving  at  2.5  feet  per  second — 1.7  miles  an  hour — ^barely  perceptible. 
Air  moving  at  3.0  feet  per  second — 2.0  miles  an  hour — perceptible. 
Air  moving  at  3.5  feet  per  second — 2.3  miles  an  hour — draft. 

The  movement  of  warm  air  is  less  perceptible  than  the  movement 
of  cool  air.^ 

*  For  a  further   discussion  of  this  subject  see  "Air  Currents  and  the  Laws 

of  Ventilation,"  by  W.  N.  Shaw. 
''■  For  Drafts  see  page   196. 


TEMPEEATUEE  OF  THE  AIE  687 


TEMPERATURE  OF  THE  AIR 

The  temperature  of  the  air  depends  mainly  upon  solar  and  ter- 
restrial radiation.  The  air  absorbs  vast  quantities  of  heat  from  the 
sun,  and  as  the  heat  of  the  earth  is  radiated  into  space  a  certain  amount 
is  again  absorbed  by  the  atmosphere.  Accordingly,  the  air  both  keeps 
the  heat  out  and  keeps  it  in.  It  makes  the  days  cooler  and  the  nights 
warmer.  "It  is  a  parasol  at  noon  and  a  blanket  at  night."  Except  for 
it  there  would  be  much  more  violent  changes  in  temperature  (Macfie). 

The  power  of  the  air  to  absorb  heat  and  to  store  heat  depends 
largely  on  its  humidity;  that  is,  on  the  amount  of  water  vapor  it  con- 
tains, for  water  vapor  is  opaque  to  heat  rays.  The  water  vapor  is  also 
a  great  reservoir  of  latent  heat.  When  water  evaporates  a  tremendous 
amount  of  latent  heat  is  carried  up  into  the  atmosphere  with  it  and 
again  becomes  actual  heat  when  the  vapor  condenses.  The  quantity 
of  heat  thus  stored  up  in  water  vapor  is  almost  incredibly  great. 

Air  expands  ^^y  of  its  volume  for  each  degree  rise  of  temperature; 
air  at  32°  F.  and  30  inches  barometric  pressure  is  usually  taken  for 
unit  of  volume.  A  cubic  foot  of  dry  air  at  32°  F.  and  30  inches  barom- 
eter weighs  566.86  grains;  at  any  other  temperature,  therefore,  its 
weight  can  be  ascertained  by  dividing  by  its  increased  volume. 

The  temperature  of  the  air  has  a  very  important  bearing  upon 
health.  Man  has  an  almost  incredible  power  of  adapting  himself  to 
wide  variations  of  temperature.  Workers  in  foundries  have  sometimes 
to  endure  a  heat  of  250°  F.  and  even  higher  for  short  periods  of  time. 
Temperatures  of  — 75°  F.  are  met  with  in  polar  expeditions.  This  is 
a  range  of  at  least  325°  F.  The  reason  that  man,  as  well  as  other 
animals,  is  able  to  maintain  a  constant  body  temperature  when  exposed 
to  such  great  variations  of  atmospheric  temperature,  is  due  not  only 
to  the  physiological  mechanism  which  regulates  heat  production  and 
elimination,  but  to  the  layers  of  air  immediately  in  contact  with  the 
skin.  We  wear  clothes  to  protect  ourselves  from  external  heat  or  cold, 
but  still  more  do  we  wear  air  for  that  purpose.  That  is  why  very  high 
temperatures  are  better  borne  when  the  air  is  in  motion,  which  facili- 
tates evaporation,  than  when  the  air  is  still,  while  extremes  of  cold 
are  better  borne  when  the  air  is  still,  for  then  we  become  clothed  in  a 
warm  blanket  of  air.  The  effect  of  heat  upon  health,  however,  cannot 
be  considered  alone,  for  it  depends  on  the  humidity  as  well  as  on  the 
movement  of  the  air.  Extremes  of  heat  and  cold  are  much  more  trying 
when  the  air  is  humid  than  when  the  air  is  dry. 

The  direct  action  of  heat  alone  as  a  cause  of  infant  mortality  has  been 
greatly  underestimated.  The  harmful  effects  of  heat  must  not  be  meas- 
ured so  much  by  the  maximum  or  even  the  mean  temperatures  of  the  out- 


688         PRESSURE,  TEMPERATURE,  AND  HUMIDITY 

side  air,  but  by  the  indoor  temperatures.  Indoor  temperatures  may 
continue  high  in  spite  of  remissions  in  the  temperature  of  the  external 
air.  The  lethal  effects  of  heat  upon  infants,  and  adults,  too,  are  in- 
creased by  the  still,  moist  air  found  in  overcrowded,  narrow  streets,  and 
poor  ventilation  of  houses. 

Exposure  of  the  body  to  dry,  cold  air  has  an  effect  similar  to  a  cold 
bath,  that  is,  there  is  an  increased  loss  of  bodily  heat,  followed  by  a 
demand  for  more.  This  demand  is  met  by  increased  oxidation  of  tissue, 
metabolic  processes  become  more  active,  and  there  is  improvement  in 
nutrition.    In  other  words,  cold  acts  as  a  stimulant  and  tonic. 

It  is  of  first  importance  that  the  arrangements  for  heating  rooms, 
offices,  schools,  etc.,  should  be  so  regulated  that  the  temperature  never 
exceeds  21°  C.  (70°  F.)  ;  especially  should  this  control  be  exercised  in 
public  rooms,  such  as  schools,  etc.  As  a  rule,  the  temperature  of  heated 
rooms  should  be  17°  to  19°  C.  (62.6°  to  68.2°  F.)  or  under.  Periodic 
variations  of  temperature  are  as  desirable  inside  of  buildings  as  in  the 
outside  temperature.  The  effect  of  temperature  upon  health  is  so 
closely  interwoven  with  humidity  that  this  relationship  is  discussed  on 
page  697. 

Methods  of  Recording  Temperature. — Mercurial  or  bimetallic  tlier- 
m.ometers  are  best  "'uited  to  take  the  temperature  of  the  air.  The  most 
accurate  mercurial  thermometers  for  this  purpose  have  an  elongated  bulb 
of  mercury  at  one  end  and  a  ring  at  the  other,  through  which  a  cord 
can  be  tied;  the  scale  should  be  etched  upon  the  glass.  A  good  ther- 
mometer of  this  type  generally  is  accurate  to  about  one-half  to  one-fifth 
of  a  degree.  Thermometers  placed  upon  a  backing  of  metal,  card,  or 
wood,  with  the  scale  painted  upon  the  backing,  are  more  ornamental 
than  accurate.  They  usually  possess  a  decided  lag  and  are,  therefore, 
not  trustworthy.  Thermometers  should  be  suspended  freely  in  the 
atmosphere  or  at  least  placed  in  a  current  of  air  sufficient  to  insure  good 
ventilation  about  the  mercury  column. 

Registering  thermometers  are  of  two  principal  types :  those  which 
record  maximum  and  minimum  temperatures,  and  those  which  make 
a  continuous  record  of  the  changes  of  temperature  that  occur. 

The  maximum  and  minimum  temperatures  furnish  but  limited  in- 
formation, and,  as  such  self-recording  thermometers  are  almost  invari- 
ably mounted  upon  a  backing,  they  consequently  have  a  considerable 
lag.  They  are  only  dependable  where  fluctuations  in  temperature  are 
not  rapid.  Under  these  circumstances  they  may  be  used  to  record 
the  highest  and  lowest  temperatures. 

For  an  intelligent  understanding  of  the  sanitary  condition  of  any 
room  or  inclosed  space  neither  single  determinations  nor  maximum  and 
minimum  records  are  sufficient.  Recording  thermometers  should  be 
placed  at  various  selected  points  and  records  should  be  obtained  cov- 


HUMIDITY  689 

ering  a  period  of  several  days.  The  best  type  of  recordiBg  thermom- 
eters depend  upon  the  movements  of  bimetallie  bars,  so  arranged  that 
as  they  contract  and  expand  they  cause  a  penpoint  to  bear  upon  a  mov- 
ing paper  scale,  and  so  leave  an  ink  trace.  The  clockwork  is  generally 
wound  up  for  a  week,  for  which  period  the  paper  scale  is  also  adapted. 

HUMIDITY 

Aqueous  Vapor. — Water  in  its  gaseous  state  is  always  present  in  the 
atmosphere.  Water  vapor  is  the  most  variable  of  the  normal  constitu- 
ents of  air,  and  also  one  of  the  most  important,  on  account  of  its  influ- 
ence upon  health.  It  is  usual  to  consider  water  vapor  apart  from  the 
other  gases  of  the  atmosphere,  although  it  is  just  as  much  a  gas  as 
oxygen  or  nitrogen,  and  conforms  to  the  general  laws  that  govern  the 
behavior  of  gases.  As  water  vapor  weighs  only  about  three-fifths  the 
weight  of  air,  dry  air  is  heavier  than  moist  air  under  equal  conditions 
of  temperature,  pressure,  etc.  It  is  customary  to  speak  of  air  "holding" 
water  vapor.  As  a  matter  of  fact,  the  air  has  nothing  to  do  with  it, 
for  it  should  always  be  clearly  observed  that  the  presence  of  water 
vapor  in  any  given  space  is  independent  of  the  presence  or  absence  of 
air  in  the  same  space.  The  amount  of  aqueous  vapor  which  a  space 
contains  depends  entirely  upon  the  temperature  and  not  upon  the  pres- 
ence or  the  pressure^  of  the  air.  At  32°  F.,  for  instance,  the  air  can 
"hold"  1/160  of  its  weight  of  water  vapor,  at  59°  F.  1/80  of  its  weight, 
at  86°  F.  1/40  of  its  weight.  Eoughly,  every  27°  F.  increase  of  tem- 
perature doubles  the  amount  of  water  vapor  the  air  can  hold  in  propor- 
tion to  its  weight.  In  this  way  the  heat  of  the  atmosphere  is  self-pro- 
tective, for  it  loads  the  air  with  water  vapor,  which  in  turn  absorbs  much 
of  the  heat.  The  latent  heat  is  again  given  off  on  condensation.  The 
actual  amount  of  water  vapor  which  the  air  can  hold  at  different  tem- 
peratures is  shown  in  the  following  table: 

A  cubic  foot  of  air  can  hold  at 

10°  F 1.1  grains 

20°    "    1.5       " 

-     30°    " 2.1       " 

40°    "    3.0       " 

50°    "    4.2       " 

60°    "    5.8       " 

T0°    "    7.9       " 

80°    "    10.0       " 

90°    "    14.3       " 

100°   '•'    19.1       " 

^A  high  barometer  retards  evaporation,  while  a  low  atmospheric  pressure 
accelerates   it.     All  volatile  liquids  evaporate  instantly  in  a  vacuum. 


690         PEESSURE,  TEMPERATURE,  AND  HUMIDITY 

As  tlic  temperature  rises  in  arithmetical  progression  Jlie  power  to 
retain  vapor  increases  with  the  rapidity  of  a  geometric  series  having 
a  ratio  of  two. 


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Fig.  85. —  Diagram  Showing  Absolute  Humidity  in  Grains  at  Different 

Temperatures. 


The  amount  of  water  vapor  in  the  air  may  be  expressed  either  by: 
(1)  its  vapor  tension.  The  tension  of  the  water  vapor  in  the  air  is 
expressed  in  inches  or  millimeters  of  mercury.  If  a  drop  of  water  is 
placed  in  a  vacuum,  say  in  a  barometer  tube,  some  of  the  water  vaporizes 


HUMIDITY  G91 

and  the  mercury  is  depressed,  owing  to  the  tension  of  the  water  vapor. 
The  amount  that  evaporates,  as  well  as  the  tension,  depends  upon  the 
temperature.  (2)  Its  weight  per  unit  volume  of  air,  i.  e.,  the  absolute 
humidity;  and  (3)  the  ratio  of  the  amount  of  water  vapor  in  the  atmos- 
phere to  the  amount  it  could  hold  at  the  temperature  in  question  if 
saturated;  that  is,  the  relative  humidity.  Complete  saturation  of  the  air 
with  moisture  is  stated  at  100,  and  lesser  amounts  hy  percentages: 
(4)  The  amount  of  water  vapor  in  the  air  may  also  he  found  from  its 
dew-point.  The  dew-point  for  any  temperature  and  humidity  is  the 
temperature  to  which  the  air  may  be  cooled  when  precipitation  takes 
place. 

The  vapor  tension  or  the  absolute  humidity  indicates  how  much 
water  vapor  the  air  contains,  while  the  relative  humidity  is  an  ex- 
pression of  how  much  vapor  it  might  contain.  The  amount  of  water 
vapor  which  air  can  hold  when  saturated  at  different  temperatures  has 
been  calculated  and  recorded  in  Glaisher's  hygrometric  tables.^  It  is, 
therefore,  very  easy,  by  referring  to  these  or  to  the  tables  in  the  U.  S. 
Weather  Bureau — Bulletin  No.  235 — to  calculate  the  relative  humid- 
ity if  we  know  the  actual  humidity  or  the  dew-point  or  vice  versa. 

The  amount  of  moisture  which  out-of-door  air  ordinarily  contains 
varies  from  about  30  per  cent,  or  less  to  saturation. 

■  In  meteorological  tables,  giving  climatic  particulars  of  any  town  or 
locality,  the  relative  humidity  is  usually  stated;  but  it  should  be  no- 
ticed that  the  relative  humidity  bears  no  constant  relationship  to  the 
absolute  humidity.  As  the  relative  humidity  varies  greatly  throughout 
the  day,  and  as  the  readings  are  not  always  taken  at  the  same  time  of 
day  in  different  localities,  it  at  once  becomes  evident  that  comparisons 
are  not  reliable.  In  fact,  a  moist  or  dry  climate  cannot  be  predicted 
from  the  relative  humidity.  Thus,  the  mean  relative  humidity  of 
Davos  is  as  high  as  79  per  cent.,  whereas  it  is  generally  known  that  the 
climate  of  Davos  is  dry.  On  the  other  hand,  in  Egypt  the  average  rela- 
tive humidity  is  very  low,  although  this  country  is  known  to  have 
a  moist  climate.  This  is  for  the  reason  that  the  humidity  readings 
in  Egypt  are  taken  from  10  A.  M.  to  6  P.  M.,  and  vary  from  30.5  per 
cent,  at  Assouan  to  51.7  per  cent,  at  Menahouse.  As  a  matter  of  fact, 
the  relative  humidity  in  Egypt  decreases  from  100  per  cent,  at  dawn 
to  23  per  cent,  at  noon,  and  may  be  quickly  altered  to  the  extent  of  50 
per  cent,  by  a  warm  wind.  The  humidity,  therefore,  through  the  hot, 
sunny  daytime  is  not  a  measure  of  the  climate,  so  far  as  moisture  and 
dryness  are  concerned. 

In  England  the  relative  humidity  averages  75  per  cent.     In  Cali- 

*The  standard  hys'rometrical  tables  in  use  the  world  over  are  those  pre- 
pared by  Mr.  James  Glaisher,  F.  R.  S.,  of  the  Royal  Observatory,  Greenwich, 
England. 


692         PRESSUEE,  TEMPERATURE,  AND  HUMIDITY 


fornia  it  drops  from  100  per  cent,  at  dawn  to  22  per  cent,  at  noon.  A 
hot  wind,  by  increasing  the  capacity  of  the  air  for  moistiire,  may  also 
lower  the  relative  humidity  very  quickly.  Thus,  the  F(")hji  wind  when  it 
reaches  the  Riviera  lowers  the  relative  humidity  50  to  00  per  cent,  in 
an  hour  or  two.  The  mean  relative  humidity  of  Denver  for  the  year 
is  only  42  per  cent.,  at  San  Diego,  on  the  coast,  72.9,  at  Los  Angeles. 
a  few  miles  inland,  66.6.  In  the  heart  of  the  Libyan  desert  the  rela- 
tive humidity  may  be  as  low  as  9  per  cent.  At  the  seaside  daily  varia- 
tions in  humidity  are  less  than  inland  (Macfie).  The  air  in  forests  is 
10  or  20  per  cent,  more  humid  than  air  in  the  open.  There  may  be  a 
very  great  difference  in  the  relative  humidity  of  outside  cool  air  and  of 
air  in  a  closed  heated  room,  in  that  the  latter  may  be  very  much  dryer. 
So  far  as  the  effect  of  humidity  upon  health  is  concerned  Dr.  Hug- 
gard  well  states :  "The  really  essential  point  is  not  the  amount  of 
moisture,  relative  or  absolute,  that  is  present,  but  the  amount  that  can 
still  be  taken  up.  This  varies  enormously  with  the  same  degree  of 
relative  humidity  at  different  temperatures,  as  the  following  table  from 
Renk  will  show:'^ 

Amount  of  vapor  that  can  still  be  taken  up  at  different  temperatures  and  the  same  relative 

hum^idity 


Temperature 

Relative  Humidity 

Absolute  Humidity 
Grams  per  Cubic  Meter 

Grams  of  Vapor  that 
can  still  be  taken  up 

-20°  C 

Per  Cent. 
60 
60 
60 
60 
60 
60 

0.638 
1.380 
2.924 
5.623 
10.298 
18.083 

0.426 

-10°  C 

0.920 

0°  C 

1.950 

10°  C 

3.749 

20°  C 

6.866 

30°  C 

12.056 

"We  see  by  this  table  that  the  same  expression,  60  per  cent,  relative 
humidity,  might  be  applied  to  air  capable  of  taking  up  0.426  gram  or 
12.056  grams  of  vapor,  and  thus  the  expression  as  a  measure  of  the 
drying  capacity  of  the  air  is  obviously  misleading. 

Dr.  Huggard  gives  a  second  very  instructive  table,  the  obverse  of 
the  above : 


Relative  Humidity 

Vapor:     Grams 

per  Cubic  Meter 

Temperature 

Present 

Capable  of  Still  Being 
Taken  Up 

3°C 

Per  Cent. 
0 
36 
53 
65 
73 
80 

0 

3.4 

6.8 

11.2 

16.9 

24.1 

6 

10°  C 

6 

15°  C 

6 

20°  C 

6 

25°  C 

6 

30°  C 

6 

HUMIDITY  693 

We  s.ee  from  this  second  table  that  air  with  relative  humidities  of 
0,  36,  53,  65,  73,  and  80  per  cent.,  and  containing  quantities  of  water 
vapor  varying  between  0  and  24.1  grams  per  cubic  meter,  are  all  ca- 
pable of  further  taking  up  exactly  the  same  amount  of  vapor.  Again 
the  expression  of  relative  humidity  is  misleading. 

When  the  relative  humidity  reaches  80  to  85  per  cent.,  moisture  con- 
denses and  begins  to  show  upon  objects  in  rooms.  This  influences  natural 
ventilation  through  porous  building  materials. 

There  may  be  a  very  marked  difference  between  the  humidity  of 
indoor  and  outdoor  air,  owing  in  part  to  the  condensation  of  moisture, 
especially  in  winter,  upon  the  cold  walls  and  windows. 

The  difference  between  external  and  internal  humidities  depends 
largely  upon  the  temperature  of  the  surfaces  in  the  room.  These  sur- 
faces, though  apparently  dry,  may,  in  fact,  hold  moisture  in  large 
quantities;  the  walls  and  ceilings  may  contain  more  water  than  all  the 
air  in  the  room.  Ordinarily  there  is  a  continual  exchange  of  moisture 
between  the  air  and  the  room  surfaces.  In  this  way  the  walls  serve 
as  a  compensating  reservoir  to  help  maintain  the  humidity  of  the  air 
approximately  constant.  Cold  walls,  cold  windows,  and  cold  surfaces 
generally  condense  the  moisture  from  the  air  so  rapidly  that  great  diffi- 
culty is  experienced  in  raising  the  relative  humidity  of  the  air  of  a  room 
under  these  circumstances. 

The  humidity  in  the  air  is  influenced  by  altitude.  The  higher  we 
go  the  air  becomes  colder  and  rarer  and,  therefore,  able  to  contain  less 
moisture.  Its  absolute  humidity,  therefore,  decreases.  Half  of  the 
total  water  vapor  of  the  atmosphere  is  below  2,000  meters.  On  the 
other  hand,  the  relative  humidity  shows  no  regular  change  with  change 
of  altitude.  Clouds  do  not  necessarily  imply  high  relative  or  absolute 
humidity  of  the  lower  atmosphere.  Eainfall  also  gives  only  a  very  gen- 
eral indication  of  the  humidity  of  the  atmosphere.  A  place  with  high 
rainfall  may  have  low  absolute  and  relative  humidity,  and  vice  versa; 
that  is,  a  rainy  district  is  not  necessarily  a  damp  district,  so  far  as  the 
atmosphere  is  concerned. 

Dew  also  bears  no  constant  relationship  to  the  humidity  of  the  atmos- 
phere, for  a  clear  sky  and  a  dry  atmosphere  favor  its  formation.  Air 
containing  mist  is  obviously  moist. 

Methods  of  Determining  Humidity  in  the  Air. — The  amount  of  water 
vapor  in  the  air  may  be  determined  either  by  (1)  weighing,  (2)  psy- 
chrometers  or  hygrometers,  (3)  the  dew-point. 

Weighing. — The  amount  of  moisture  in  the  air  may  be  determined 
by  passing  a  given  volume  of  air  through  a  tube  or  flask  containing  an 
hygroscopic  substance,  such  as  calcium  chlorid  or  sulphuric  acid.  If 
sulphuric  acid  is  used  small  flasks  are  filled  with  pieces  of  pumice  which 
have  been  heated  to  a  high  temperature  over  a  Bunsen  burner,  and 


694         TRESSURE,  TEMPERATURE,  AND  HUMIDITY 


r 


Fig.    86.— Sling 
psychrometer. 


dropped  while  hot  in  concentrated  sulpiiuric  acid;  re- 
moved,  and   quickly   drained. 

The  increase  in  Aveight  represents  the  amount  of 
moisture  in  the  volume  of  air  passed  through  the 
fxasks,  or  the  absolute  humidity.  Knowing  the  tem- 
perature of  the  air,  it  is  then  easy  to  determine  the 
relative  humidity  by  reference  to  tables  of  maximum 
water  capacity  for  certain  volumes  of  air  at  varying 
degrees  of  temperature. 

PsYOHROMETERS. — The  most  convenient  of  all 
methods  for  measuring  atmospheric  moisture  is  to 
observe  the  temperature  of  evaporation,  that  is,  the 
difference  between  the  temperatures  indicated  by  wet 
and  dry  bulb  thermometers.  The  United  States 
Weather  Bureau  regards  the  sling  psychrometer  as  the 
most  reliable  instrument  for  this  purpose.  In  special 
cases  rotary  fans  or  other  means  may  be  employed  to 
move  the  air  rapidly  over  stationary  thermometer 
bulbs. 

The  sling  •psychrometer  consists  of  a  pair  of  ther- 
mometers provided  with  a  handle,  which  permits  them 
to  be  whirled  rapidly  (see  Fig.  86).  The  bulb  of  the 
lower  of  the  two  thermometers  is  covered  with  thin 
muslin,  which  is  wet  at  the  time  an  observation  is 
made.  This  muslin  covering  should  be  kept  in  good 
condition  and  should  be  frequently  renewed.  It  is 
also  desirable  to  use  pure  water.  The  so-called  wet 
bulb  is  thoroughly  saturated  by  dipping  it  into  dis- 
tilled water.  The  thermometers  are  then  whirled  rap- 
idly for  15  or  20  seconds,  stopped,  and  quickly  read, 
the  wet  bulb  first.  This  reading  is  kept  in  mind,  the 
psychrometers  immediately  whirled  again  and  a  sec- 
ond reading  taken.  This  is  repeated  three  or  four 
times  or  more,  if  necessary,  until  at  least  two  succes- 
sive readings  of  the  wet  bulb  are  found  to  agree  very 
closely,  thereby  showing  that  it  has  reached  its  lowest 
temperature.  A  minute  or  more  is  generally  required 
to  secure  a  correct  reading.  The  psyclirometer  should 
not  be  whirled  in  the  direct  rays  of  the  sun,  and  if 
used  out  of  doors  the  observer  should  face  the  wind. 
It  is  a  good  plan,  while  whirling  the  instrument,  to 
step  back  and  forth  a  few  steps  to  further  prevent  the 
presence  of  the  observer's  body  from  giving  rise  to 
erroneous  observations. 


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695 


696         PRESSURE,  TEMPERATURE,  AND  HUMIDITY 


111  corrccl  iii,ii^  ]),syclir()ni('tri('  ()])S('rvaiioi)s  ilio  Hhnos|ilici-ic  pressure 
at  the  time  must  be  obtained,  and  the  results  deduced  from  the  tables 
based  on  a  pressure  nearest  that  observed.  The  difference  in  the  tem- 
perature between  the  wet  and  the  dry  bulb  is  computed  to  the  nearest 
tenth  of  a  degree.  Having  the  temperature  and  the  pressure  of  the  air 
and  the  depression  of  the  wet  bulb,  it  is  only  necessary  to  read  directly 
from  the  tables  the  dew-point,  the  vapor  pressure,  and  the  relative  humid- 
ity. These  tables  will  be  found  in  Bulletin  No.  235  of  the  United  States 
Weather  Bureau,    A  condensed  table  is  given  in  Fig.  87. 

The  Hair  Hygrometer. — This 
apparatus  depends  upon  the  expan- 
sion and  contraction  of  a  suitably 
prepared  hair  under  the  influence  of 
moisture.  It  can  be  made  a  reason- 
ably accurate  instrument,  and  some 
types  are  arranged  for  continuous 
record.  One  of  the  principal  diffi- 
culties with  hair  hygrometers  is  that 
a  sufficient  current  of  air  does  not 
always  come  in  contact  with  them. 

The  Dew-point. — The  dew- 
point  may  be  obtained  by  direct  ob- 
servation from  Regnault's  appa- 
ratus, shown  in  Fig.  88.  This  in- 
strument consists  essentially  of  a 
thin  polished  silver  tube  a,  cemented 
upon  the  lower  end  of  a  long  glass 
tube,  as  shown.  The  stopper  closing 
the  upper  end  of  the  glass  tube  is 
fitted  with  two  lateral  tubes  of  hard 
rubber  &  and  c,  and  also  carries  a  delicate  themometer,  the  bulb  of  which 
is  placed  near  the  center  of  the  silver  tube.  The  tube  h  extends  to  the 
bottom  of  the  silver  tube;  c  projects  but  a  short  distance  through  the 
cork.-  A  rubber  aspirating  apparatus,  as  shown,  is  connected  with  the 
tube  h,  and  a  long  tube  joined  to  c  serves  to  carry  off  the  fumes.  The 
apparatus  is  held  in  a  clamp  faced  with  cork  or  other  non-conducting 
substance. 

Observations  are  made  by  filling  the  silver  cup  with  ether  or  similar 
volatile  liquid,  which  is  caused  to  evaporate  and  cool  the  silver  cup 
by  manipulating  the  aspirating  bulb.  At  the  proper  point  of  cooling 
a  deposit  of  dew  is  seen  to  form  on  the  polished  silver  surface.  The 
object  is  to  ascertain  accurately  the  temperature  at  which  the  dew  will 
just  deposit.  It  is  necessary  that  the  temperature  be  lowered  very  slowly 
at  the  critical  point,  also  that  there  be  plenty  of  liquid  in  the  cup,  and 


Fig.  88. — Dew-point  Apparatus. 


HUMIDITY  697 

that  it  be  agitated  sufficiently  to  have  a  uniform  temperature  throughout, 
and,  finally,  the  surface  of  the  silver  must  be  perfectly  clean  and  in  a 
favorable  light,  so  that  the  faintest  deposit  of  dew  is  at  once  visible.  The 
temperature  shown  by  the  thermometer  at  this  moment  may  be  regarded 
as  the  temperature  of  the  dew-point.  Knowing  the  dew-point,  the  humid- 
ity of  the  air  may  be  found  by  reference  to  the  above-mentioned  tables. 

Relation  of  Humidity  and  Temperature  to  Health. — The  physiolog- 
ical significance  of  moisture  in  the  air  varies  with  many  factors,  but 
especially  with  temperature.  In  a  general  way  it  may  be  said  that  moist 
air  is  depressing  and  enervating,  while  dry  air  is  tonic  and  stimulating; 
also  that  cold  air  is  tonic,  while  warm  air  is  depressing.  Metabolism 
is  slowed  in  warm  air,  quickened  in  cold  air.  The  human  body  can 
adapt  itself  to  wide  variations  in  heat  and  humidity,  and  by  means  of 
suitable  clothing  and  food  the  range  may  be  greatly  increased.  Certain 
combinations  of  heat  and  humidity  are  trying  or  even  hurtful ;  the  most 
mischievous  combinations  are  cold  damp  air  and  warm  moist  air,  also 
an  excessively  dry  air,  especially  when  artificially  warmed.  Many 
climates  in  which  people  are  reasonably  healthy  have  a  relatively  high 
humidity,  and  some  regions  famed  for  their  salubrity  are  notoriously 
dry  and  arid.  The  frequently  changing  temperatures  and  variable 
amounts  of  water  vapor  of  most  climates  may  be  beneficial  in  stimulat- 
ing the  heat-regulating  mechanism. 

The  temperature  and  humidity  of  the  air  affect  health  mainly  by 
influencing  the  heat-regulating  mechanism  of  the  body.  More  heat  is 
produced  within  the  body  than  is  required,  hence  heat  must  be  lost, 
else  heat  stagnation  or  heat  stroke  will  result.  The  temperature  of  the 
air,  but  still  more  its  humidity,  influences  heat  loss.  It  will,  there- 
fore, be  necessary  to  briefly  review  the  mechanism  by  which  the  con- 
stant temperature  of  the  body  is  maintained. 

The  chief  source  of  the  body  heat  comes  from  the  food  we  eat.  Ap- 
proximately 80  per  cent,  of  the  food  we  eat  is  used  to  furnish  heat 
to  maintain  the  body  temperature,  while  only  about  20  per  cent,  fur- 
nishes energy  in  the  form  of  motion.  Heat  is  lost  from  the  body 
chiefly  in  two  ways:  (1)  by  keat  transfer^  or  loss  by  radiation,  con- 
duction, and  convection;  (2)  by  evaporation,  chiefly  by  the  evapora- 
tion of  the  water  of- perspiration.  Pettenkofer  and  Voit  estimated  the 
loss  of  water  by  the  lungs  at  286  gramS;,  and  from  the  skin  at  from  500 
to  1,700  grams  daily.  This  will  give  some  idea  of  the  magnitude  of  the 
effects  here  concerned.  The  loss  by  heat  transfer  diminishes  as  the 
temperature  of  the  surrounding  air  rises.  The  temperature  of  the 
body  would  rise  when  the  atmospheric  temperature  goes  above  70°  F. 
were  not  perspiration  then  secreted.  So  long  aa  the  perspiration  can 
evaporate  freely  the  heat  production  and  heat  loss  are  balanced.  With 
a  high  humidity  evaporation  is  lessened  and  the  balance  is  maintained 


698         PRESSUKE,  TEMPEIiATUliE,  AND  HUMIDITY 

by  rushing  blood  to  tlio  skin,  wliicli  (-auscs  an  elevation  of  tlx;  tempera- 
ture of  the  surface,  and  thus  the  loss  of  heat  by  radiation,  conduction, 
and  convection  is  facilitated. 

Humidity  influences  the  output  of  heat  from  the  body  in  two  ways: 
(1)  it  increases  the  conductivity  of  atmosphere  for  heat — a  cooling 
influence — hence  cold  moist  air  is  chilling;  (3)  it  interferes  with  evap- 
oration of  perspiration — a  heating  influence — hence  warm  moist  air  is 
enervating.  There  is  a  neutral  zone,  around  G8°  F.,  at  which  humidity 
has  comparatively  little  effect.  Hence,  if  the  temperature  of  a  room 
is  kept  just  right  and  the  occupants  are  sitting  still,  it  makes  little 
difference  whether  the  air  is  humid  or  dry.  However,  a  difference  of 
a  few  degrees  above  or  below  this  temperature  will  have  a  marked  influ- 
ence. 

The  so-called  "comfort  zone"  has  a  maximum  temperature,  7C,  a 
minimum  humidity,  30  per  cent. ;  a  minimum  temperature,  55  to  60°, 
and  a  maximum  humidity,  55  per  cent.  This  is  the  range  which  most 
people  in  temperate  climates  find  agreeable.  However,  large  numbers 
of  people  remain  comfortable  and  well  in  climates  that  would  be  trying 
if  the  change  were  made  suddenly.  The  body  possesses  great  powers 
of  adaptability  in  this  regard,  which  is  one  of  the  factors  in  accli- 
matization. 

Eubner  and  his  coworkers  showed  that  the  evaporation  of  water 
from  the  body  cannot  be  regarded  as  being  dependent  merely  on  the 
percentage  humidity  of  the  atmosphere.  The  temperature  of  the  layer 
of  air  in  contact  with  the  body  is  the  factor  of  great  importance.  Thin 
clothes  and  still  air,  under  certain  conditions  of  external  temperature, 
may  favor  evaporation,  while  nakedness  and  moving  air  favor  conduction 
and  radiation.  The  heat-losing  mechanisms  of  the  body  are  adjustable 
to  varying  conditions  within  wide  limitations,  so  that  diminished  loss  by 
evaporation  is  compensated  for  by  increased  loss  by  conduction  and 
radiation. 

The  amount  of  moisture  in  the  air  conducive  to  health  and  well- 
being  is  often  stated  to  be  somewhere  between  50  and  75  per  cent, 
relative  humidity.  These  figures  may  be  very  misleading.  There  is 
no  such  thing  as  a  normal  humidity,  for  the  amount  of  moisture  in 
relation  to  health  depends  upon  the  temperature,  clothing,  motion  of 
the  air ;  also  upon  diet  and  muscular  activity  and  other  factors.  Neither 
the  relative  humidity  nor  the  absolute  humidity  nor  the  temperature  of 
the  air  alone  is  a  satisfactory  guide  as  to  its  condition  in  relation  to 
health.  One  factor  alone  gives  the  sanitarian  scant  information;  how- 
ever, the  temperature  as  registered  upon  the  wet-bulb  thermometer  is 
most  significant. 

Importance  of  the  Wet-bulb  Temperature. — The  indiTidual  sus- 
ceptibility to   temperatures   depends   entirely   on   the   temperature   re- 


HUMIDITY  699 

corded  by  the  wet-bulb  thermometer/  no  matter  what  the  dry  bulb  regis- 
ters. Hill,  Rubner,  Pembrey,  Boycott,  Cadman,  Nagel,  and  practically 
all  authorities  agree  with  Haklane  that  the  air  of  workrooms  should 
not  exceed  70°  F.  by  the  wet-bulb  thermometer. 

Eubner  states  that  an  untrained  man  can  be  in  comfort  in  a  tem- 
perature of  75°  F.  and  80  per  cent,  humidity  (wet  bulb  about  70°  F.) 
only  when  he  is  quiet.  At  73.4°  F.  and  GO  per  cent,  humidity  he  found 
a  resting  man  lost  by  evaporation  75  grams  of  water  per  hour,  and  at 
84  per  cent,  humidity  (wet  bulb  70°  F.)  only  19  grams.  These  figures 
show  that  three-quarters  of  the  heat  loss  may  be  maintained  by  con- 
duction and  radiation  when  the  wet  bulb  reaches  70°  F. 

Cadman  concludes  that  at : 

72°  wet  bulb  —  Inconvenience  is  experienced,  unless  heavy  clothing  is  removed 

and  light  clothing  worn. 
78°    "       "     Little  inconvenience  is  felt  if  considerable  bare  body  surface 

is  exposed.     Hard  work  is  much  facilitated  if  a  perceptible 

current  is  passing  over  the  body. 
82°    "       "     ....  If  clothes  be  removed,  and  maximum  body  surface  exposed, 

work  can  be  clone  providing  current  of  air  is  available. 
85°    "       "     Body  temperature  becomes  affected,  and  only  light  work  is 

possible. 

Boycott  made  the  following  significant  observations  upon  himself: 
"At  rest  and  stripped  I  found  that  my  body  temperature  rose  rap- 
idly if  the  wet  bulb  exceed  88°  or  90°  F.  with  a  dry  bulb  of  about 
100°,  though  no  rise  occurred  with  a  dry  bulb  of  110°  and  wet  bulb 
of  less  than  85°.  I  have  on  many  occasions  spent  periods  of  about  an 
hour  in  doing  ordinary  laboratory  v/ork  in  air  with  the  dry  bulb  at 
95°  and  the  wet  bulb  at  about  65°  without  any  material  discomfort.  If, 
however,  the  wet  bulb  rises  to  88°  or  90°,  one's  body  temperature  begins 
to  go  up,  even  when  completely  at  rest,  and  one  becomes  exceedingly 
uncomfortable  and  on  occasions  feels  very  ill.  These  sensations  can  be, 
to  some  extent,  remedied  by  local  cooling  of  the  skin  (e.  g.,  cold  water 
on  the  head),  but  the  rise  of  body  temperature  is  progressive  and  must 
eventually  end  in  heat-stroke." 

A  man  is  much  less  efficient  in  a  warm  moist  atmosphere ;  hence  it 
is  an  advantage  to  both  em.ployer  and  employee  that  work  be  performed 
at  temperatures  below  70°  F.  by  the  wet  blilb.  At  the  lower  tempera- 
tures work  is  done  faster,  more  efficiently,  and  with  less  fatigue,  dis- 
comfort, and  injury  to  health.  To  work  in  a  warm  moist  atmosphere 
increases  the  temperature,  pulse,  and  loss  of  moisture  out  of  propor- 
tion to  the  work  done.  It  is  the  master's  pockets  which  sulfer  under 
such  conditions,  for  the  workers  instinctively  avoid  the  discomfort  of 
overheating  themselves  through  lessened  exertion. 

*  One  of  the  thermometers  of  a  psychrometer  is  known  as  the  wet  bulb. 
See  page  694, 


700         PRESSURE,  TEMPERATURE,  AND  HUMIDITY 

Effects  of  Warm  Moist  Air. — In  a  hot,  moist  atmosphere  an  undue 
amount  of  blood  is  brought  to  the  surface  of  the  body,  mental  and  physi- 
cal activity  is  reduced,  a  feeling  of  depression  is  felt,  and  the  resulting 
rise  in  temperature  of  the  body  influences  the  entire  nervous  and  circu- 
lating systems.  When  air  above  88°  F.  becomes  saturated  evaporation 
can  no  longer  compensate  for  decrease  in  radiation,  and  the  body  tem- 
perature accordingly  rises  and  heat-strike  may  ensue.  The  injurious 
effects  of  the  summer  heat  are  practically  always  the  result  of  combined 
heat  and  humidity. 

According  to  Rubner  and  Lewaschew,  when  the  air  is  very  humid 
the  heat  loss  by  evaporation  is  very  much  lessened,  and,  accordingly,  at 
80  per  cent,  humidity  and  temperature  of  24°  C.  (75.3°  F.)  becomes 
after  a  time  insupportable  to  a  man  unaccustomed  to  it,  and  exposure 
to  it  is  only  possible  with  complete  muscular  rest.  If,  however,  the 
air  is  very  dry  a  temperature  of  24°  to  29°  C.  (75.2°  to  84.2°  F.) 
can  be  usually  endured.  These  temperatures  are  often  exceeded  in  the 
summer  time  in  America.  By  practice  a  certain  amount  of  accom- 
modation to  the  effects  of  a  hot  moist  climate  may  be  acquired. 

There  is  no  known  serious  injury  to  health  caused  by  working  in  a 
warm  moist  air,  provided  that  a  considerable  rise  of  body  temperature 
is  avoided.  The  effects  of  heat  and  moisture  may  be  diminished  by  light 
clothing,  bare  legs  and  arms,  whereby  the  loss  of  heat  from  the  skin 
is  increased. 

Working  in  moist,  overheated  rooms  has  the  further  disadvantage 
of  wetting  the  clothes  with  perspiration,  which  causes  discomfort,  dirt, 
and  untidiness,  and  liability  to  chilling  the  surface  on  going  outdoors. 

A  poorly  ventilated  room  in  which  the  air  becomes  vitiated  is  usually 
a  warm  moist  atmosphere,  and  the  ill  effects  of  a  vitiated  atmosphere 
are  mainly  caused  by  the  heat  and  moisture.  One  of  the  most  mis- 
chievous effects  of  a  warm  moist  atmosphere  is  disinclination  to  mental 
and  physical  effort  and  loss  of  appetite. 

Effects  of  Cold  Damp  Air. — When  such  air  is  injurious  the  victim  is 
usually  underclad,  improperly  fed,  or  has  been  living  an  indoor  life. 
In  certain  cases  cold  damp  must  always  be  injurious,  as,  for  instance, 
where  the  vital  forces  are  at  a  low  ebb  and  where  there  is  restricted 
capacity  for  making  heat,  such  as  infancy  or  old  age;  in  cases  of  kidney 
disease,  where  hindrance  of  evaporation  means  extra  work  for  the  kid- 
neys; also  in  cases  where  there  is  a  tendency  to  rheumatism  or  disorders 
of  metabolism.  The  effects  of  cold  damp  air  may  be  neutralized  by 
proper  clothing,  by  muscular  activity,  and,  to  a  limited  extent,  by  diet. 

Just  how  cold  damp  air  influences  health  is  not  well  understood. 
It  throws  an  added  load  upon  the  heat-producing  mechanism  to  main- 
tain the  body  temperature;  the  strain  falls  especially  upon  digestion 
and  metabolism,  and  also  upon  the  circulation  and  the  kidneys,  and 


HUMIDITY 


701 


indirectly  upon  the  nervous  system.  Macfie  suggests  that:  "Dry  air 
quickens  metabolism  both  through  its  cooling  and  drying  capacity,  while 
damp  air  slows  it  by  diminishing  loss  of  water.  It  is  possible  that  much 
of  the  harm  attributed  to  damp  and  to  cold  is  due  to  a  depression  of 
metabolism  and  accumulation  of  harmful  waste  products  in  the  body." 
Dr.  H.  I.  Bowditch  in  1863  formulated  the  law  of  soil  moisture,  and 
believed  that  tuberculosis  was  more  common  over  moist  soils  than  dry 
ones.  According  to  our  present  conception,  the  relation  between  damp- 
ness or  moist  soil  and  tuberculosis  is  quite  indirect;  if  there  is  any  con- 
nection it  is  due  merely  to  the  fact  that  the  combination  of  cold  and 
dampness  depresses  vitality  and  thereby  lowers  resistance. 

A  person  will  shiver  and  the  lips  turn  blue  on  a  very  cold  misty 
day,  especially  when  facing  the  wind.  This  is  due  to  the  fact  that  under 
such  conditions  the  respiration  is  shallow,  probably  as  the  result  of  a 
protective  mechanism ;  and  the  interchange  of  gases  in  the  lungs  is 
slowed,  for  moisture  interferes  with  diffusion. 

A  healthy  man  may  daily  move  in  and  breathe  cold  damp  air  with- 
out suffering  in  health  to  any  appreciable  extent;  however,  it  is  gener- 
ally believed  that  a  qold  damp  air  predisposes  to  affections  of  the  re- 
spiratory passages,  to  rheumatism,  and  neuralgias. 

Effects  of  Warm  Dry  Air. — A  relatively  dry  air  feels  better  than  moist 
air  at  most  temperatures.  The  stimulating  and  pleasant  effects  of  a 
dry  climate  can  only  be  appreciated  by  one  who  has  visited  an  arid 
region — such  as  our  southwestern  plateau.  However,  when  air  is  ab- 
normally dry,  especially  if  warm,  the  evaporation  from  the  body  is 
greatly  increased.  Thus,  Rubner  and  Lewaschew  found  that  a  man 
weighing  58  kilograms  gave  off  the  following  amounts  of  carbon  dioxid 
and  moisture  in  one  hour  at  different  temperatures  in  dry  and  moist 
air: 


Dry  Air 

Moist  Air 

Temperature 

Relative 

Humidity 

of  Air 

CO2 

mo 

Relative 

Humidity 

of  Air 

CO2 

H2O 

15°  C 

20°  C 

25°  C 

29°  C 

8% 
5% 
6% 
6% 

32.2  gm. 
30.0  gm. 
31.7  gm. 
32.4  gm. 

36 

54 

75 

103 

3gm. 
1  gm. 
4  gm. 
3gm. 

89% 
82% 
81% 

34.9  gm. 

28.3  gm. 

31.4  gm. 

9 
15 
23 

0  gm. 
3gm. 
9  gm. 

Air  that  is  warm  and  at  the  same  time  abnormally  dry,  such  as  that 
produced  by  furnace  heat,^  causes  an  excessive  loss  of  moisture  and  con- 
centration of  the  fluids  in  the  tissues  and  organs  of  the  body.  Man 
consists  of  58.5  per  cent,  of  water.     A  very  small  percentage  of  loss 

^  See  page  764. 


702         PKESSURE,  TEMPEKATUEE,  AND  HUMIDITY 

may  be  serious;  when  the  percentage  reaches  21  per  cent,  death  results. 
The  warmed  and  dried  atmosphere  of  our  overheated  houses  gives  a 
sense  of  chilliness,  owing  to  excessive  evaporation,  and  favors  irritation 
and  infection  of  the  respiratory  mucous  membranes.  If  a  room  at  68° 
F.  is  not  warm  enough  for  a  healthy  person,  we  may  be  sure  that  it  is 
because  the  humidity  is  too  low. 

The  problem  of  constructing  buildings  in  such  a  way  as  to  keep  the 
interior  up  to  a  fair  degree  of  humidity  is  a  large  one.  So  far  engineers 
have  made  little  practical  progress  toward  its  solution.  Satisfactory 
devices  may  be  had  to  improve  the  moisture  in  large  public  buildings, 
but  these  devices  have  so  far  proved  too  expensive  for  private  dwellings, 
offices,  or  schoolrooms. 

The  humidity  in  living  rooms  may  be  improved  by  setting  about 
growing  plants  and  porous  dishes,  such  as  flower  pots  full  of  water.  If 
such  receptacles  are  set  near  electric  fans  evaporation  is  facilitated. 
Pans  or  pots  of  water  may  also  be  placed  upon  the  radiator. 

A  coolj  dry  air  is  bracing.  All  the  body  functions  are  more  active, 
breathing  is  deeper  and  niore  frequent,  the  circulation  of  the  blood  is 
increased;  digestion,  assimilation,  and  metabolism  are  stimulated. 


CHAPTER    III 
MISCELLANEOUS 

Odors. — People  have  always  believed,  and  still  naturally  cling  to  the 
notion,  that  anything  that  smells  bad  must  be  detrimental  to  health. 
Science  has  demonstrated  that  our  sense  of  smell  is  a  poor  sanitary 
guide.  While  disagreeable  odors  may  not  be  harmful,  they  should  be 
eliminated  for  esthetic  and  psychological  reasons,  as  well  as  for  decency 
and  cleanliness. 

Odors  in  a  living  room  come  mostly  from  human  sources.  The 
sources  of  these  odors  are:  foul  breath,  decaying  teeth,  unclean  mouths, 
nasal  catarrh,  sudoriferous  glands,  especially  those  of  the  pubes,  feet, 
and  axillae,  also  gases  from  the  stomach  and  bowels.  The  decomposi- 
tion of  matter  on  the  skin  and  also  in  the  clothes  adds  a  very  disagree- 
able odor,  accentuated  in  a  warm  moist  atmosphere.  The  peculiar  odor 
in  some  rooms,  especially  sick  rooms,  seems  to  be  none  of  these;  just 
what  constitutes  the  somewhat  characteristic  man-smell  is  not  known. 

While  odors  may  be  very  unpleasant,  they  are  not  known  to  seriously 
influence  health;  contrary  to  common  opinion,  they  are  not  by  any 
means  a  reliable  sign  of  danger.  The  presence  of  bacteria  or  dust  in 
the  atmosphere  has  no  special  relation  to  odors.  Some  poisonous  gases, 
such  as  carbon  monoxid,  are  practically  inodorous. 

The  air  of  inhabited  rooms  ordinarily  must  be  quite  full  of  various 
scents  which  we  do  not  appreciate,  either  because  our  sense  of  smell 
is  not  keen  enough,  or  because  we  have  become  so  accustomed  to  them 
that  they  are  not  noticed.  An  atmosphere  that  does  not  appear  to  be 
unpleasant  while  remaining  in  a  room  may  seem  intolerable  upon  re- 
turning to  it  after  a  period  in  the  fresh  outdoor  air.  Man's  sense  of 
smell  is  not  keen  when  compared  to  that  of  some  of  the  lower  animals; 
nevertheless  it  is  extremely  sensitive  to  certain  odors.  Thus,  it  can 
determine  0.000,000,03  gram  of  musk.  The  acuteness  of  the  sense  of 
smell  varies  markedly  in  different  individuals. 

Odorous  molecules  detach  themselves  from  the  surface  of  solids 
and  liquids  by  simple  evaporation,  by  oxidation  and  by  hydrolytic  de- 
composition. Currents  of  air  will  carry  vapors  as  they  carry  dust  along 
with  them  to  quite  a  distance. 

It  is  well-known  that  we  can  perceive  odors  much  more  readily  when 
the  air  is  moist  than  when  it  is  dry.     It  is  also  known  that  the  mucous 

703 


704  MTSCELLAXEOTJS 

meml)raiio  of  ilie  nose  must  be  moist  in  order  lluil  fin  odor  Ix;  perceived. 
Some  fishes,  partieularly  sharks,  have  a  well-developed  sense  of:  smell. 
Passy  determined  the  least  amounts  of  odorous  matter  that  ean  be 
perceived  by  us.  He  gives  the  following  figures  per  liter  of  air  in 
which  certain  substances  are  dissolved  and  can  be  perceived. 

Camphor    0,005  milligram  per  liter  of  air 

Ether 0.004  to  0.005 "         "       ''       "     " 

Sulphureted  hydrogen    0.0005  "         "       "       "     " 

Mercaptan    0.000,000,04    "         "       "       "     " 

The  olfactory  nerves  soon  tire  of  m,ost  odors,  and  after  a  certain 
time,  fail  to  respond.  While  in  this  condition  they  can  at  once  perceive 
the  sudden  appearance  of  other  odors.  For  example:  Aronson  found 
that  persons  having  become  insensible  to  the  odor  of  iodin  from  continu- 
ous use  found  their  perception-  to  the  odor  of  ether  at  once  perfect. 
Ordinary  ventilation  does  not  remove  the  vapors  which  are  held  on 
solid  surfaces  by  absorption.  A  jet  of  compressed  air  frequently  played 
against  the  interior  surface  of  buildings  and  against  the  clothing  will 
remove  this  source  of  odors.  Hence,  the  value  of  opening  windows 
and  thoroughly  flushing  out  rooms  from  time  to  time. 

When  a  room  smells  stuffy  and  close  it  may  be  taken  as  a  fairly 
reliable  index  that  the  air  is  vitiated;  this  is  especially  true  in  a  clean 
room  not  complicated  with  odors  from  clothing  and  sources  other  than 
man.  In  fact,  the  odors  observed  upon  entering  a  room  from  the  out- 
side fresh  air  often  furnish  better  evidence  of  imperfect  ventilation  than 
laboratory  tests. 

De  Chaumout  made  accurate  observations  and  found  that  when  the 
COo  amounts  to  6  parts  per  10,000  the  atmosphere  begins  to  smell 
close  and  stuffy.  Pettenkoffer  found  air  containing  7.5  parts  of  COo 
per  10,000  from  the  expired  breath  to  have  a  marked  odor,  and  10 
parts  a  very  unpleasant  odor.  With  a  little  practice  various  grades  of 
vitiated  air  can  be  detected  up  to  10  or  12  parts  of  CO2  per  10,000. 

The  odors  from  marshes  and  from  decomposing  organic  matter  are 
not  apparently  hurtful.  One  of  the  most  famous  stenches  that  has 
been  recorded,  if  not  the  most  famous,  was  that  which  arose  in  1858 
and  1859  from  the  Thames,  which  at  that  time  was  grossly  polluted 
with  the  sewage  of  London  (Sedgwick).  Dr.  Budd  insisted  that  no 
very  serious  results  followed.  After  giving  his  proof  Budd  ^  states : 
"Before  these  inexorable  figures  the  illusion  of  half  a  century  van- 
ished in  a  moment."     We  now  know  that  odors  in  the  air   bear  no 

*Dr.  William  Budd:  "Typhoid  Fever:  Its  Nature,  Mode  of  Spreading,  and 
Prevention,"  pp.  148-151.  London,  1873.  Tliis  is  a  remarkable  contribution 
which  the  student  is  adyised  to  read. 


MISCELLANEOUS  705 

reference  to  contagion  or  infection  and,  however  unpleasant,  need  not 
be  feared  as  such.     Sewer  "gas"  is  discussed  on  page  729. 

The  effect  of  odors  upon  health  is  not  at  all  understood.  When  we 
sense  a  pleasant  smell  we  involuntarily  take  deeper  breaths;  on  the 
other  hand,  unpleasant  odors  diminish  the  respiratory  exchange.  The 
latter  are  accordingly  harmful  to  that  extent  and  the  former  stimulat- 
ing. Odors  influence  the  nervous  system  in  various  ways;  some  stim- 
ulate, others  depress  psychic  activity;  some  odors  have  a  well-known 
influence  upon  sexuality.  Occasionally  odors  are  so  disagreeable  that 
they  induce  nausea,  even  vomiting.  It  is  remarkable  how  quickly  we 
may  become  accustomed  to  odors,  but  because  our  sense  of  smell  has 
been  dulled  is  no  guarantee  that  the  cause  of  the  odors  may  not  con- 
tinue to  produce  its  effects.  Leonard  Hill  thinks  that  it  is  very  doubt- 
ful if  the  unpleasant  smelling  exhalations  of  the  bodies  of  men  have 
any  ill  effects  on  men  accustomed  to  them,  and  not  of  esthetic  tem- 
perament. 

Odors  in  a  confined  space  may  be  removed  by  washing  the  air  through 
a  spray  of  water.  The  water  absorbs  the  odors  so  that  the  washwater 
smells  like  a  stuffy  room.  The  odors  may  also  be  neutralized  or  con- 
cealed with  ozone,  formaldehyd,  and  other  substances,  but  the  best 
deodorants  are  cleanliness  and  ventilation. 

Light. — All  the  rays  of  the  sun  pass  through  the  atmosphere  before 
they  reach  the  earth.^  The  air  acts  as  a  differential  filter,  holding  back 
many  rays,  especially  those  of  shorter  wave-length;  that  is,  the  ultra- 
violet end  of  the  spectrum.  These  rays  have  marked  chemical  power. 
Bunsen  and  Eoscoe  investigated  this  question  of  the  atmospheric  absorp- 
tion of  the  chemical  rays  of  the  sun,  and  came  to  the  conclusion  that 
in  passing  through  the  atmosphere  the  ultraviolet  rays  lost  about  66  per 
cent,  of  their  chemical  power.  We  have  already  seen  that  many  of  the 
heat  rays  are  also  absorbed  by  the  atmosphere.  "More  heat  and  we 
might  be  roasted,  more  light. and  we  might  be  blinded,  more  chemical 
energy  and  we  might  be  slain  like  the  microbes." 

The  rays  of  shorter  wave-lengths  have  chemical  and  photodynamic 
powers  which  must  have  an  important  relation  to  health.  These  rays 
act  upon  photographic  negatives;  hasten  the  hatching  of  flies'  eggs 
and  frogs'  eggs;  they  sunburn  the  skin  and  produce  freckles;  they  kill 
many  bacteria,  including  the  tubercle  bacilli;  they  cause  heliotropism ; 
they  combine  chlorin  and  hydrogen  into  hydrochloric  acid;  they  cause 
the  oxidation  of  oxalic  acid  and  other  chemical  reactions;  they  blacken 
silver  salts.  It  has  been  shown  that  in  buckwheat  poisoning  (fagotox- 
ismus)  these  actinic  rays  play  an  important  part.     The  skin  eruptions 

*  The  waves   of   light  are  not  waves  of  the  atmosphere,  but   of  the   ether ; 
however,   they   are   absorbed,    reflected   or   refracted   by   the   dust   and   moisture 
contained  in  the  air.     It  is  convenient  to  consider  light,   as  well  as  electricity 
and  radio-activity,  at  this  point. 
24 


706  MISCELLANEOUS 

upon  the  exposed  surfaces  in  pellagra  are  also  explained  upon  the  photo- 
dynamic  theory,  that  is,  the  poison  is  believed  to  be  activated  by  certain 
light  rays. 

The  air  as  a  filter  of  the  sun's  rays  bears  a  very  important  but 
little  understood  relation  to  life.  It  is  now  well  known  that  some  of 
the  sun's  rays  have  intense  chemical  and  "vital"  power.  We  know  some- 
thing about  the  chemical  rays,  the  luminous  rays,  and  the  calorific  rays, 
but  there  are  doubtless  many  ether  vibrations  of  which  we  know  noth- 
ing, Macfie  speculates  that,  "even,  indeed,  as  the  crops  of  the  northern 
zone  outstrip  the  crops  in  the  south  of  France,  so  at  certain  times  may 
the  activity  of  nations  be  stimulated  or  depressed  by  atmospheric  varia- 
tions affecting  the  composition  of  solar  radiation." 

Aschenheim  ^  found  that  after  an  hour^s  exposure  of  the  body  to  the 
direct  action  of  sunlight  there  was  a  general  leukocytosis  in  the  periph- 
eral blood  with  a  relative  increase  in  the  lymphocytes  and  a  decrease 
in  polymorphonuclear  leukocytes  in  80  per  cent,  of  the  cases.  Lympho- 
cytes are  regarded  as  one  of  the  body's  defenses  against  tuberculosis,  and 
Aschenheim  suggests  that  this  may  account  for  the  favorable  effect  of 
sunlight  on  tuberculosis.  Prolonged  exposure  of  the  body  to  bright  sun- 
light in  those  who  have  not  been  accustomed  to  its  rays  may  be  deleter- 
ious and  even  dangerous.  The  damage  is  more  than  the  sunburn  result- 
ing, for  it  may  even  lead  to  serous  meningitis.^ 

The  physiological  action  of  light  is  just  beginning  to  receive  the 
serious  attention  it  deserves.  We  are  all  familiar  with  the  calming 
effect  of  the  dim  religious  light  of  churches  and  the  stimulating  effect 
of  the  glare  of  the  theater.  The  intense  light  of  the  tropics  and  of 
high  altitudes  is  believed  in  some  way  to  bring  on  nervous  disorders, 
but  the  relation  is  but  vaguely  understood.  Some  of  the  ill  effects 
attributed  to  bad  air  and  poor  ventilation  are  due  in  part  to  the  over- 
stimulation of  excessive  illumination. 

For  the  purposes  of  ocular  hygiene  the  direction,  source,  power 
and  color  of  artificial  illumination  are  all  important.  The  amount  of 
illumination  should  not  be  judged  by  the  brightness  of  the  lamps, 
but  by  the  amount  of  light  at  the  place  it  is  needed.  This  varies ;  thus 
more  light  is  needed  for  sewing  on  black  cloth  than  on  white  cloth. 
The  light  should  be  steady.  A  flickering  light  tires  the  muscles  that 
govern  accommodation  and  leads  to  fatigue  and  pain.  Eeading  in  rail- 
way trains  causes  similar  strain :  the  eye  muscles  tire  of  trying  to  follow 
the  shaking  page.  It  is  contrary  to  the  principles  of  ocular  hygiene 
to  face  a  glaring  light,  especially  when  reading,  writing,  or  any  other 
work  requiring  close  application.     Even  though  the  light  may  come 

*  Aschenheim,  E. :  "Effect  of  the  Sun's  Rays  on  the  Leucocyte  Count," 
Zeitschr.  f.  Kinderheilkunde,  Berlin,  IX,  2. 

*R6mer:     Deutsch.  med.  Wchnschr.,  July  8,  1915,  p.  832. 


MISCELLAI^EOUS  707 

from  above  glaring  reflections  from  polished  metal  or  brass,  from  brightly 
varnished  surfaces,  or  even  from  glossy  white  paper  may  be  very  trying 
because  a  bright  light  from  below  falls  on  the  part  of  the  retina  which 
commonly  gets  light  only  from  grass  or  dark  surfaces.  For  the  same 
reason  glare  from  snow  and  sand  is  not  only  disagreeable  on  account 
of  its  intensity,  but  because  of  the  unusual  direction  from  which  it 
comes. 

Proper  lighting  has  a  direct  bearing  on  the  economic  running  of 
a  factory,  and  also  on  the  efficiency  of  the  men  and  the  safety  of  the 
work-people.  Glare  from  any  source  is  to  be  avoided,  and  the  light  must 
be  directed  on  to  the  work  in  such  a  way  that  the  greatest  intensity 
will  be  where  it  is  wanted.  The  general  rule  is  to  have  at  least  1  sq.  ft. 
of  window  to  every  5  sq.  ft.  of  floor  space.  Under  no  conditions  must 
the  source  of  the  light  fall  directly  in  the  eyes  nor  should  there  be  any 
surfaces  which  will  reflect  a  strong  light  into  the  eyes  of  the  work- 
men. Furthermore,  the  light  must  be  of  such  a  character  that  the  back- 
ground is  relieved  from  gloom.  In  other  words,  there  should  be  little 
contrast  between  the  light  and  unlighted  parts  of  the  factory.  Flicker- 
ing lights  should  always  be  avoided.  Good  illumination  can  only  be 
prescribed  where  the  uses  to  which  the  light  is  to  be  put  is  known.  (See 
also  pages  1085  and  1093.) 

Method  for  Measuring  Illumination. — The  method  which  is 
recommended  as  a  standard  procedure  depends  on  the  use  of  photo- 
sensitive paper,  such  as  can  be  obtained  from  any  dealer  in  photographic 
materials.  By  exposing  the  sensitized  paper  through  a  slot  in  a  card- 
board for  a  sufficient  period  of  time,  and  noting  the  number  of  seconds 
or  minutes  consumed  to  match  in  depth  a  standard  shade  of  color,  the 
intensity  of  light  can  be  determined  with  accuracy.  If  a  fresh  piece 
of  paper  is  exposed  to  the  direct  rays  of  the  sun  for  three  seconds  it 
will  assume  a  shade  which  can  be  used  as  a  standard  for  a  given  series 
of  tests.  The  intensity  of  light  at  other  points  may  be  compared  with 
this  by  noting  the  number  of  seconds  required  to  color  a  fresh  piece  of 
paper  from  the  same  lot  to  the  same  shade. 

This  method  is  inferior  to  photometers,  several  patterns  of  which 
are  in  use.  It  is  not  sufficient  for  the  purposes  of  ocular  hygiene  to 
know  the  intensity,  of  the  light  at  any  particular  point.  We  must 
know  the  color  and  the  amount  of  light  that  enters  the  eye ;  this  amount 
is  governed  by  the  size  of  the  pupil,  which  in  turn  is  governed  by  the 
direction  of  the  light,  and  many  other  factors.  There  is  therefore  no 
single  method  for  testing  illumination  with  reference  to  ocular  hygiene. 

Electricity. — The  question  of  electricity  is  also  a  question  of  vibra- 
tions, not  of  the  air,  but  of  ether,  and  one  shrouded  in  much  obscurity. 
The  electric  potential  of  the  air  varies  considerably.  It  is  highest  in 
winter  and  lowest  in  summer,  and  shows  diurnal  variations.     It  is  in- 


708 


MISCELLANEOUS 


creased  by  winds  and  is  especially  increased  by  the  condensation  of 
vapor.     It  also  increases  as  we  ascend. 

It  is  assumed  that  electric  changes  in  the  air  and  in  other  objects 
surrounding  us  exercise  an  influence  on  health  and  vitality,  but  the  in- 
fluence is  obscure  and  mainly  a  matter  of  conjecture. 

Radioactivity. — Soon  after  the  discovery  of  radium  by  the  Curies  it 
was  proved,  chiefly  through  the  investigations  of  Elster  and  Geitel, 
that  the  air  and  soil  and  certain  mineral  springs  contained  radioactive 
substances.  Newly  fallen  rain  and  snow  are  also  radioactive.  Air 
drawn  from  the  soil  by  means  of  a  pipe,  or  air  shut  up  in  underground 
cellars  and  caverns,  is  specially  radioactive,  as  is  also  the  air  on  moun- 
tain tops.  The  air  in  clear  weather  has  greater  radioactivity  than  in 
dull  weather. 

Certainly  radioactive  substances  have  important  physiological,  physi- 
cal, and  chemical  effects.  They  ionize  the  air,  rendering  it  a  conductor 
of  electricity;  they  cause  a  fluorescence  of  certain  chemical  substances; 
they  produce  a  sensation  of  light  if  they  strike  the  eye;  and  if  too  active 
may  cause  destruction  of  living  tissue.  Substances  so  potent  must  have 
some  physiological  influence. 

Smoke. — Smoke  is  a  product  of  combustion  and  consists  of  a  mixture 
of  gases  containing  solid  particles.  Ordinary  smoke  consists  largely 
of  unburned  carbon  particles,  hydrocarbons,  and  other  pyroligneous 
products;  gases,  some  of  them  poisonous,  such  as  carbon  monoxid;  also 
mineral  acids,  etc.  Angus  Smith  gives  the  following  analysis  of  smoke 
from  a  common  house  fire : 


Smoke  from  a  common  house  fire 


Carbon 
Dioxid 

Carbon 
Monoxid 

Oxygen 

Nitrogen 

Gas  from  chimney  4  feet  above  the  / 
fireplace \ 

0.35 
1.65 

'o'38 

16.93 
19.29 

80.02 
78.68 

Gas  from  the  middle  of  a  good  fire,  f 
A  great  mass  of  coal  over  the  fire,  j 
the  gas  taken  from  below  the  glow-  ] 
ing  mass [ 

19.46 
20.90 
17.50 
17.44 

0.09 
0.10 

"o'eo 

0.39 

80.45 
79.00 
80.04 

82.17 

A  heap  of  glowing  coal,  gas  taken  close 
to   spot   where    carbonic   oxid   was  ■ 
burning 

15.43 
18.17 

3.49 
2.48 

0.96 

80.12 
79.35 

Gas  from  clear  fire  below f 

16.10 
17.21 
18.20 

'o;99 

4.95 
4.25 

78.95 

Gas  from  the  same  fire  at  upper  part,  -1 
1  inch  below  the  surface [ 

78.54 
78.21 

Dr.  Cohen  of  the  Manchester  Air  Analysis  Committee  gives  the 
following  analysis  of  soot  collected  from  the  roofs  of  glass  houses  in 
Ivew  and  Chelsea: 


MISCELLAJTEOUS 


709 


Chelsea 

Kew 

Per  Cent. 

Per  Cent. 

39.0 

42.5 

12.3 

4.8 

2.0 

4.3 

4.6 

1.4 

0.8 

1.4 

1.1 

2.6 

31.2 

41.5 

5.8 

5.3 

Carbon 

Hydrocarbons 

Organic  bases  (pyridins,  etc.) 

Sulphuric  acid 

Hydrochloric  acid 

Ammonia 

Metallic  iron  and  magnetic  oxid  of  iron 

Mineral  matter  (chiefly  silica  and  ferric  oxid) 
Water  not  determined  (say  difference) 


Large  manufacturing  chimneys  are  the  chief  offenders.  There  are 
two  main  causes  of  smoky  chimneys :  ( 1 )  insufficient  boiler  capacity, 
and  (2)  improper  stoking.  The  cure  of  the  smoke  nuisance  consists 
in  the  installation  of  boilers  of  sufficient  power  so  that  they  need  not 
be  forced, .  and  the  use  of  mechanical  stokers.  The  electrification  of 
railroads  and  the  more  general  use  of  electric  power  generated  from 
water  pressure  help  materially  to  lessen  the  amount  of  smoke  in 
cities. 

The  London  County  Council  permits  black  smoke  for  five  minutes 
after  the  lighting  of  furnaces.  Other  towns  allow  as  much  as  15  minutes. 
Most  laws  distinguish  between  black  smoke  and  white  smoke,  although 
the  one  is  about  as  pernicious  as  the  other. 

In  Boston  the  density  of  the  smoke  is  graded  into  four  classes,  in 
accordance  with  Eingelmann's  chart.  This  is  a  rather  complicated  sys- 
tem, depending  upon  the  character  of  the  stack,  the  density  of  the  smoke, 
and  the  time,  as  shown  in  Fig.  89. 

The  amount  of  smoke  in  some  manufacturing  centers  is  almost  in- 
credible. Dr.  W.  N.  Shaw  estimates  that  London  gives  to  the  atmos- 
phere every  day  about  7,000,000  tons  of  smoky  air  containing  over  400 
tons  of  soot,  and  he  calculates  that  smoke  deprives  London  of  about  one- 
sixth  its  possible  sunlight  and  daylight  in  summer  and  about  one-half 
its  possible  sunlight  and  daylight  in  winter. 

The  injurious  effect  of  smoke  on  health  has  perhaps  been  overesti- 
mated. It  acts  directly  and  indirectly.  Directly  it  irritates  the  mucous 
membranes  of  the  upper  respiratory  passages,  and  Asher  and  also 
Eubner  believe  that  it  increases  the  mortality  from  acute  pulmonary 
diseases.  They  state  that  smoke  and  soot  predispose  to  acute  pulmonary 
tuberculosis.  Indirectly  smoke  is  a  source  of  dirt  and  general  nuisance 
and  leads  to  depression  of  the  spirits.  It  shuts  out  the  light,  soils 
with  soot,  and  deters  the  opening  of  windows  in  order  to  let  in  fresh 
air.  The  presence  of  mineral  acids  in  the  air  has  a  corrosive  influence 
upon  inorganic  substances,  and  doubtless  acts  injuriously  upon  plant 
and  animal  life.  The  economic  losses  from  the  soiling  action  of  soot 
are  enormous.    Even  if  it  were  not  injurious  to  health,  smoke  is  so  evi- 


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MISCELLANEOUS  711 

dent  a  nuisance  that  communities  are  justified  in  every  effort  to  check 
and  prevent  this  growing  abomination. 

Klotz  ^  characterizes  pulmonary  anthracosis  as  a  community  disease. 
Klotz  found  as  much  as  1.2  to  5.3  grams  of  carbon  in  the  lungs  of  per- 
sons living  in  Pittsburgh,  while  only  0.14  and  0.4  grams  in  the  lungs  of 
two  residents  in  Ann  Arbor,  Mich.  Anthracosis  then  affects  city  dwell- 
ers in  proportion  to  the  amount  of  smoke  in  the  air.  The  amount  of 
carbon  in  the  lungs  is  dependent  upon  the  amount  inhaled.  Carbon  in 
the  lungs  causes  a  loss  of  elasticity  of  the  tissue;  structural  changes, 
especially  fibrosis,  about  the  anthracotic  deposits;  the  air  spaces  are 
encroached  upon,  resulting  in  compensatory  emphysema.  When  anthra- 
cosis is  well  marked  it  seriously  impairs  the  function  of  the  lungs. 
Pleural  adhesions  do  not  develop  as  a  result  of  the  deposit. 

Smoke  polluted  with  poisonous  chemical  vapors  may  be  quite  serious. 
Thus,  hydrogen  sulphid,  found  in  large  quantities  in  the  smoke  gener- 
ated in  sulphate  of  ammonia  and  tar  works  and  from  alkali  wastes,  is 
a  poisonous  gas.  The  arsenical  vapors  given  off  chiefly  from  lead  and 
copper  smelters  kill  vegetation  for  wide  areas  around. 

Fog. — Fogs  are  caused  by  the  condensation  of  water  vapor  on  par- 
ticles of  dust.  Dust  particles  have  a  varying  capacity  for  condensing 
and  attracting  moisture,  depending  upon  their  power  of  radiating  heat 
and  on  their  affinity  for  water.  Carbon  dust  is  hygroscopic  and,  there- 
fore, encourages  fogs.  The  ammonia  and  sulphuric  acid  in  smoky  air 
also  occasion  and  aggravate  fog.  The  air  of  manufacturing  cities,  there- 
fore, possesses  all  the  elements  to  form  a  fine  persistent  fog  which  forms 
a  "chemical  pall"  between  the  city  and  the  sky. 

The  more  carbon  a  fog  contains  the  blacker  it  is.  The  general  re- 
sult of  a  fog  is  to  shut  out  sunlight  and  fresh  air  and  to  "partially 
suffocate  unfortunate  citizens  in  clouds  of  noxious  chemicals."  Fog 
contains  all  the  irritating  properties  of  smoke  in  a  concentrated  form, 
and  it  also  in  a  measure  prevents  the  escape  of  the  city-made  carbon 
dioxid.  The  COg  in  the  city  air  during  a  fog  may  rise  to  10  parts  per 
10,000.  If  smoke  is  bad  fog  is  ten  times  worse.  It  has  been  shown 
that  during  city  fogs  sickness  increases  and  the  death  rate  rises.  From 
the  economic  standpoint  fog  causes  greater  financial  losses  than  smoke. 
Eussell  calculates  the  annual  loss  to  the  people  of  London  from  fog  to 
total  about  $9,000,000  a  year.  The  main  items  in  this  loss  consist  in 
extra  washing,  including  extra  soap,  the  damage  to  dresses,  curtains, 
carpets,  and  textile  fabrics,  the  replacing  of  wall-papers,  and  the  paint- 
ing of  houses,  the  restoring  of  gilt  and  metal  work,  the  slow  destruction 
of  granite,  marble,  and  stonework  of  buildings,  the  extra  cost  of  arti- 
ficial illumination,  etc.  This  estimate  does  not  include  the  losses  result- 
ing from  its  action  on  health. 

^Amer.  Jour.  Public  Health,   1914,  IV,  p.  887. 


712  MISCELLANEOUS 

Dust. — Dust  is  not  only  a  nuisance,  but  under  certain  conditions  is 
known  to  be  prejudicial  to  health.  Dust  is  in  reality  a  normal  and  very 
important  constituent  of  the  air;  it  exists  everywhere  in  the  atmosphere 
and  profoundly  affects  some  of  the  physical  conditions  of  our  environ- 
ment. One  of  the  most  important  functions  of  dust  is  to  limit  the 
humidity  of  the  air  by  causing  the  precipitation  of  moisture  in  the  form 
of  rain,  and  to  help  control  temperature  by  the  formation  of  clouds, 
mists,  and  fogs.  Aitken,  who  has  made  a  special  study  of  this  subject, 
says  that  without  dust  "every  blade  of  grass  and  every  branch  of  tree 
would  drip  with  moisture  deposited  by  the  passing  air;  our  dresses 
would  become  wet  and  dripping,  and  umbrellas  useless ;  but  our  miseries 
would  not  end  here.  The  insides  of  our  houses  would  become  wet; 
the  walls  and  every  object  in  the  room  would  run  with  moisture." 
Without  dust  there  would  be  no  rain,  no  clouds,  no  mist,  for  the  water 
vapor  which  condenses  upon  each  particle  of  dust  forms  the  nucleus 
of  a  raindrop. 

Dust  disperses  the  light  and  decreases  the  transparency  of  the  at- 
mosphere, especially  if  the  atmosphere  be  also  humid.  What  is  known 
as  haze  is  really  dust  carrying  a  minute  amount  of  moisture. 

Although  dust  particles  are  universally  present  in  the  known  at- 
mosphere, they  are  very  irregularly  distributed.  Organic  dust  exists 
only  in  the  lower  strata,  while  inorganic  particles  are  found  wherever 
the  air  has  been  examined.  Ordinarily  there  is  more  dust  indoors  than 
in  outdoor  air.  The  size  of  the  dust  particles  varies  enormously,  from 
gross  masses  to  microscopic  and  ultramicroscopic  particles.  The  vast 
numbers  and  universal  presence  of  these  particles  may  be  realized  by 
examining  a  sunbeam.  Air  free  of  dust  is  an  artificial  product  obtained 
only  with  special  care  and  in  small  amounts  in  the  laboratory. 

Most  of  the  dust  is  torn  from  the  earth  by  the  winds;  much  of  it 
comes  from  the  carbon  and  other  particles  in  smoke;  considerable 
amounts  consist  of  minute  grains  of  salt  derived  from  sea  spray;  and 
great  quantities  are  added  by  volcanoes.  Finally,  the  air  contains  in- 
terplanetary particles  which  fall  through  it  in  a  constant  shower. 

The  spectrum  shows  the  bands  of  sodium  everywhere  in  the  atmos- 
phere. This  is  lifted  into  the  air  by  the  wind  from  the  sea  spray. 
The  water  evaporates,  leaving  the  salt  particles  to  float  about  at  the 
will  of  the  wind. 

Organic  dust  consists  of  the  dry  and  disintegrated  particles  which 
are  blown  into  the  air  from  the  animal  and  plant  kingdoms.  They 
consist  of  epithelial  scales,  seed,  spores,  bacteria,  pollen,  plant  cells, 
fluff  of  various  kinds,  bits  of  insects,  starch,  pus  cells,  algae,  rotifers, 
fragments  of  hair,  feathers,  and  bits  of  tissue,  fibers  of  cotton,  etc. 

The  inorganic  dust,  which  is  derived  mostly  from  the  soil,  from 
the  sea,  and  from  interplanetary  space,  consists  chiefly  of  silica,  alumin- 


MISCELLANEOUS  713 

ium  silicate,  calcium  carbonate,  calcium  phosphate,  magnesia,  iron  oxid, 
sodium  chlorid,  etc. 

Modern  cities  are  dust  producers.  Whipple  found  the  number  of 
dust  particles  visible  with  a  magnification  of  100  diameters,  at  the  air 
inlets  of  some  of  the  commercial  buildings  in  Boston,  as  determined  by 
microscopical  counts,  to  range  from  100,000  to  nearly  1,000,000  per 
cubic  feet. 

The  number  of  dust  particles  in  a  room  is  inversely  proportioned 
to  the  amount  of  fresh  air  supplied.  Ordinary  air  washers  remove 
from  20  per  cent  to  70  per  cent  of  the  dust. 

Dust  particles  may  be  carried  enormous  distances  by  the  winds. 
Ehrenberg  detected  organisms  belonging  to  Africa  in  the  air  of  Ber- 
lin; and  fragments  of  infusoria  belonging  to  the  plains  of  America 
in  the  air  of  Portugal.  The  smoke  of  the  burning  of  Chicago  reached 
to  the  Pacific  coast.  The  volcanic  dust  of  Krakatoa,  consisting  chiefly 
of  glassy  pumice,  was  found  for  years  in  our  atmosphere,  and  it  is 
assumed  that  some  of  it  may  have  traveled  several  times  around  the 
world.  Macfie  has  seen  in  the  Canary  Islands  clouds  of  dust  sufficient 
to  obscure  the  sun,  though  the  dust  had  come  all  the  way  from,  the 
African  mainland.  All  of  us  living  on  the  Atlantic  seaboard  have 
seen  the  yellow  days  caused  by  forest  fires  several  thousands  of  miles 
away. 

Dust  and  Disease. — "Normal"  atmospheric  dust,  free  from  bacteria, 
causes  no  appreciable  irritation  of  the  healthy  respiratory  mucous  mem- 
branes. Dust  becomes  injurious  when  excessive  in  amount  or  when  irri- 
tating in  character,  or  when  it  contains  injurious  microorganisms;  the 
injury  also  depends  upon  the  constancy  of  its  presence  and  somewhat 
upon  the  susceptibility  of  the  individual. 

Dust  may  act  indirectly  as  a  predisposing  cause  of  many  infections, 
as  well  as  directly  irritating  and  infiaming  the  respiratory  passages. 
The  statement  that  dust  opens  the  door  to  tuberculosis  and  other  infec- 
tions of  the  air  passages,  such  as  common  colds,  influenza,  pneumonia, 
etc.,  can  no  longer  be  questioned.  We  must  first  limit  ourselves  to  a 
consideration  of  the  effect  of  dust  free  of  noxious  bacteria;  in  the  next 
section  we  will  discuss  the  question  of  bacteria  in  the  air. 

The  general  effect  of  mineral  dust  breathed  for  a  long  period  of  time 
is  to  cause  an  irritation  of  the  mucous  membranes  and  an  inflammatory 
condition  of  the  lung  tissue.  The  term  pneumonokoniosis  is  a  general 
name  for  affections  of  this  kind.  The  term  is  modified  according  to 
the  various  kinds  of  dust.  Thus,  anthracosis  is  caused  by  coal  dust; 
siderosis  by  iron  or  steel  dust;  silicosis  or  chalicosis  by  stone  dust; 
hysinosis  by  cotton  particles  or  vegetable  fiber  dust. 

In  certain  cases  the  dust  is  retained  as  deposits  in  the  lungs  and 
neighboring  lymph  glands  without  further   damage.      The  lungs  and 


714  MISCELLANEOUS 

bronchial  glands  of  all  adults  are  more  or  less  discolored  from  particles, 
which  are  constantly  inhaled.  The  particles  are  taken  up  by  the  phago- 
cytes and  deposited  in  the  lymphatic  spaces  of  the  lung  or  carried  to  the 
neighboring  lymph  glands,  where  they  are  enmeshed.  Under  certain 
circumstances  the  dust  irritates  the  delicate  structures  and  leads  to  in- 
fections and  destruction  of  tissue.  Thus,  we  hear  of  stone  mason's 
phthisis,  steel  grinder's  phthisis,  and  potter's  rot.  Among  the  dusty 
trades  may  be  mentioned  pottery  and  earthenware  manufacture,  cutlery 
and  file-making,  certain  departments  of  glass-making,  copper,  iron,  lead, 
and  steel  manufacturing,  stone-cutting,  chimney-sweeping,  textile  trades, 
etc.  Oliver  ("Disease  of  Occupation")  examined  the  atmosphere  in 
which  the  brushers-off,  the  finishers,  and  the  porcelain-makers  generally 
work,  and  found  it  to  contain  640  million  particles  of  dust  per  cubic 
meter  of  air,  while  several  of  the  finishers,  i.  e.,  the  persons  whose  work 
consists  in  removing  the  excess  of  the  dried  glaze  on  the  ware,  are 
often  breathing  an  atmosphere  containing  680  million  particles  of  dust 
to  the  cubic  meter.  It  is  little  wonder  that  bronchitis  and  phthisis  are 
common.^ 

Dust  consisting  of  inorganic  particles  is  more  harmful  than  dust 
consisting  of  organic  particles,  because  the  former  are  sharper  and  more 
irritating.  House  dust  is  more  harmful  than  outside  dust,  not  only 
because  there  is  more  of  it,  especially  in  badly  ventilated  and  ill-kept 
rooms,  but  because  it  is  more  apt  to  contain  living  pathogenic  bacteria. 
House  dust  may  be  kept  down  by  cleanliness  and  avoidance  of  dry  dusting 
and  sweeping;  the  use  of  vacuum  cleaning;  and  by  a  free  system  of 
ventilation.  Much  house  dust  is  blown  in  from  the  outside,  and  some 
of  its  comes  in  on  dirty  shoes.  In  buildings  ventilated  with  a  mechani- 
cal system  the  air  may  be  filtered  through  bags  or  passed  through  a 
water  curtain,  which  will  eliminate  much  dust.  Oiling  floors  with  a  wax 
or  paraffin  mixture  helps  to  keep  down  indoor  dust.  Carpets  tacked  down 
are  sanitary  abominations  and  should  be  replaced  with  rugs  that  permit 
outdoor  cleaning  and  sunning. 

Street  dust  contains  coal  dust,  metallic  dust  from  the  operation  of 
trolley  cars,  material  swept  from  houses  and  from  shaking  rugs  from 
windows,  the  grinding  up  of  roadbeds  by  vehicles,  ashes,  and  other  ma- 
terials blown  from  barrels  and  teams;  the  bacteria  are  derived  from 
dried  fecal  matter  from  horses  and  other  animals,  dried  sputum,  the 
soil,  and  a  variety  of  other  sources.  Street  dust  may  contain  pathogenic 
organisms,  such  as  the  tubercle  bacillus,  many  varieties  of  cocci,  the 
colon  bacillus.  Bacillus  aerogenes  capsulatus,  and  possibly,  under  spe- 
cial conditions,  tetanus,  malignant  edema,  and  occasionally  other  path- 
ogenic microorganisms.     Street  dust,  therefore,  becomes  more  than  a 

*  For  a  discussion  of  the  dusty  trades,  see  chapter  on  Industrial  Hygiene. 
Anthracosis  is  considered  on  page  711. 


MISCELLANEOUS  715 

nuisance,  for  it  is  not  only  irritating,  but  may  be  a  source  of  infection. 

To  keep  down  street  dust  requires,  first  of  all,  a  well-constructed 
road  with  a  good  surface,  oiled  or  properly  cared  for;  the  control  of 
animals;  the  covering  of  ash  barrels  and  carts  hauling  dusty  loads; 
the  use  of  automobile  vacuum  cleaners  to  replace  the  old  or  the  pres- 
ent-day methods  of  dry  sweeping.  Attention  must  also  be  given  to 
spitting  on  sidewalks  and  streets,  the  enforcement  of  smoke  ordinances, 
the  more  extensive  flushing  of  streets,  and  general  attention  to  cleanli- 
ness. 

The  pollen  of  certain  plants  flying  in  the  air  as  dust  leads  to  hay 
fever  in  susceptible  individuals  (see  Anaphylaxis,  page  457). 

Methods  for  Examining  Dust. — Petri  Dish  Method. — The  simplest 
and  one  of  the  most  useful  methods  of  determining  the  amount  of 
dust  and  its  composition  is  by  means  of  suitable  receptacles,  such  as 
Petri  dishes,  upon  which  the  dust  is  allowed  to  settle  for  a  sufficient 
period  of  time  to  enable  a  considerable  quantity  to  accumulate.  Particles 
are  then  examined  under  the  microscope,  or,  if  desired,  they  can  be 
gathered  upon  a  watch  glass  and  weighed. 

Weighing. — The  air  may  be  passed  through  cotton  or  filters  of  other 
material,  the  quantity  of  air  being  measured  either  by  means  of  a  gas 
meter  or  other  device  and  the  increase  in  weight  of  the  filter  deter- 
mined. Whatever  the  filtering  medium  the  quantity  of  air  should  be 
large,  in  order  that  the  quantity  of  dust  may  be  appreciable  in  amount 
and  be  fairly  representative.  By  weighing  the  filtering  material  before 
and  after  passing  the  air  through  it,  the  aggregate  weight  of  dust  in 
the  quantity  of  air  taken  for  examination  can  be  determined.  It  is 
necessary  to  guard  against  increase  in  weight  of  the  filtering  material 
through  the  absorption  of  water.  This  can  be  done  by  placing  the 
filtering  material  in  a  desiccator  before  and  after  filtration  and  just 
before  weighing  in  each  case. 

The  Koniscope. — The  koniscope,  invented  by  Professor  John  Ait- 
ken,  consists  of  two  brass  tubes  connected  at  right  angles  and  suitably 
fitted  with  stopcocks  and  a  small  air  pum,p.  By  exhausting  the  air 
from  one  of  the  tubes,  allowing  the  space  to  become  saturated  with 
water  vapor  by  evaporation  from  wet  blotting  paper  within,  and  then 
allowing  this  moisture  to  condense  upon  the  dusty  atmosphere  under 
examination,  clouds  of  difEerent  degrees  of  density  will  form  inside  the 
tube.  The  approximate  density  of  the  clouds  can  be  measured  by  look- 
ing through  the  tubes,  windows  being  provided  for  this  purpose.  A  table 
is  supplied  with  the  instrument  to  give  the  approximate  number  of  dust 
particles  corresponding  to  clouds  of  difEerent  degrees  of  density. 


CHAPTEE  IV 
BACTEEIA  AND  POISONOUS  GASES  IN  THE  AIK 

BACTERIA  IN  THE  AIR 

The  number  of  bacteria  in  the  air  ordinarily  has  a  direct  relation 
to  the  amount  of  dust ;  in  fact,  many  of  the  bacteria  in  the  air  are 
attached  to  dust  particles.  Bacteria  in  the  air  are  commonly  consid- 
ered as  one  kind  of  dust,  but  on  account  of  their  significance  they  are 
given  separate  consideration. 

Bacteria  are  not  found  everywhere  in  the  air;  uninhabited  places 
are  quite  free  and  the  number  diminishes  as  we  ascend. 

Bacteria  do  not  multiply  in  the  air;  in  fact,  most  of  them  soon 
die,  especially  when  exposed  in  dry  air  to  sunshine.  For  the  most  part, 
the  bacteria  in  the  air  belong  to  the  harmless  varieties,  although  the 
number  and  kind  vary  greatly  with  circumstances.  They  come  chiefly 
from  the  soil  and  are  carried  into  the  air  by  the  wind  and  traffic  move- 
ments ;  that  is,  bacteria  in  the  air  are  derived  from  practically  the  same 
sources  as  dust.  The  dangerous  bacteria  in  the  air,  however,  come 
directly  or  indirectly  from  man  and  some  of  the  lower  animals. 

The  number  of  bacteria  differs  greatly  with  the  local  conditions. 
There  are  more  in  the  air  of  towns  than  in  the  open  country;  few 
in  high  mountains,  desert  places,  or  at  sea;  more  in  windy  weather 
than  calm  air;  more  indoors  than  in  outside  air;  more  in  dry  air  than 
in  moist  air;  more  before  than  after  rain.  The  air  of  badly  ventilated 
rooms,  especially  if  not  kept  clean,  contains  very  many  bacteria,  and 
more  when  occupied,  as  the  movements  of  the  occupants  stir  up  the 
dust. 

Mi  quel  of  the  Observatory  of  Montsouris  studied  the  number  of 
bacteria  in  the  air  of  various  localities.  He  found  about  150  per  cubic 
foot  in  the  air  of  Paris,  but  only  6  after  rain;  on  the  top  of  the  Pan- 
theon he  found  11/2  5  in  the  streets  about  12  per  cubic  foot;  in  a  neg- 
lected hospital  3,170;  in  a  gram  of  laboratory  dust  75,000  and  in  a 
gram  of  house  dust  2,100,000. 

Fliigge  considers  that  on  the  average  there  are  about  one  hundred 
microorganisms  to  a  cubic  meter  of  city  air — an  average  evidently  be- 
low that  of  Paris. 

Dr.  Jean  Binot  did  not  find  a  single  bacterium  in  100  liters  of 

716 


BACTERIA  m  THE  AIR  717 

outside  air  taken  at  the  summit  of  Mont  Blanc;  and  he  found  a  pro- 
gressive decrease  in  the  number  as  the  height  increased.  Thus,  he 
found : 


At  Montanvert 49 

At  the  Mer  de  Glace 23 

At  the  Place  de  I'Aiguille .- 14 

At  the  Grand  Malet 8 

At  the  Grand  Plateau 6 

On  the  summit 0 


Again,  Graham  Smith  found  at  the  top  of  the  Clock  Tower  of  the 
Houses  of  Parliament  in  London  only  one-third  of  the  number  at 
ground  level. 

Whipple  found  1,330  bacteria  per  cubic  feet  in  the  air,  at  the  street 
level,  while  at  the  tenth  story  of  the  John  Hancock  building  in  Boston 
the  air  contained  330. 

Speaking  broadly,  from  two  to  three  hundred  times  as  many  par- 
ticles of  dust  as  bacteria  are  found  in  the  outside  air  of  cities. 

Haldane  found  256  bacteria  per  cubic  foot  of  air  in  an  unventilated 
room  compared  to  practically  none  in  a  ventilated  room. 

Pasteur,  in  experiments  that  will  ever  remain  classic,  exposed  or- 
ganic infusions  in  flasks  to  the  air  of  various  places,  and  used  the  re- 
sults thus  obtained  to  prove  the  presence  or  absence  of  bacteria  in  the 
air  and  to  dispel  the  illusion  of  spontaneous  generation.  Of  20  such 
flasks  exposed  to  the  air  of  the  Mer  de  Glace  19  showed  no  contamina- 
tion. About  the  same  time  (1875)  Tyndall  exposed  27  flasks  contain- 
ing an  infusion  to  the  air  of  the  Aletsch  glacier  (8,000  feet)  ;  none 
showed  putrefaction,  while  90  per  cent,  of  the  flasks  opened  in  a 
hayloft  were  "smitten." 

It  is  estimated  that  a  person  living  in  London  breathes  about  300,- 
000  microbes  in  the  inspired  air  each  day. 

The  expired  air,  during  normal  respirations,  is  practically  bacteria- 
free,  no  matter  how  many  may  be  contained  in  the  inspired  air.  The 
moist  mucous  membranes  of  the  upper  respiratory  passages  act  as  a 
bacterial  trap.  When  the  expired  air  contains  bacteria  it  is  only  as  a 
result  of  coughing,  sneezing,  talking,  or  other  forced  expiratory  efforts 
(see  Droplet  Infection). 

The  harmful  bacteria  in  the  air  and  the  danger  of  contracting  dis- 
ease through  air-borne  infection  are  considered  below. 

Method  for  Determining  Bacteria  in  the  Air. — A  rough  idea  of  the 
bacterial  population  of  the  air  may  be  obtained  by  exposing  suitable 
culture  media  in  Petri  plates  for  various  periods  of  time,  and  counting 
the  colonies  which  develop  from  the  germs  falling  upon  them. 

A  large  number  of  different  devices  have  been  described  for  a  more 


718     BACTEEIA  AND  POISONOUS  GASES  IN  THE  AIR 


Fig.  90. — Magnus  As- 

PIEATOB. 


accurate  determination  of  the  number  of  bacteria  in  the  air.  These 
are  all  adaptations  of  three  general  methods:  (1)  filtration  of  air;  (2) 
bubbling  air  through  some  liquid  medium;  (3)  precipitating  the  bac- 
teria from  a  given  volume  of  air.  Each  of  these  methods  can  be  made 
to  give  fairly  satisfactory  results  in  the  hands  of 
competent  workers,  but  the  Committee  of  the 
American  Public  Health  Association  recom- 
mend the  following  method  of  Petri  on  account 
of  its  simplicity  and  general  applicability: 

Filtration  Method  of  Petri. — The  filter 
tubes  are  glass  tubes  l^/^  cm.  in  diameter  and 
10  cm.  long.  In  the  end  of  each  is  placed  a  per- 
forated cork  stopper,  through  which  a  glass  tube 
6  inm.  in  diameter  is  passed.  The  filtering  ma- 
terial consists  of  sand  which  has  been  passed 
through  a  100-mesh  sieve.  The  sand  in  the  filter 
tube  is  1  cm.  deep  and  supported  by  a  layer  of 
bolting  cloth  covering  the  cork.  Two  filter  tubes 
are  connected  in  tandem,  and  a  measured  volume 
of  air,  10  liters  or  more,  is  drawn  through  at  a 
constant  rate  by  suction.  The  suction  is  applied  by  means  of  an  aspira- 
tor of  known  volume,  preferably  one  of  the  double  or  continuous  type. 
Either  the  Magnus  aspirator  (Fig.  90)  or  the  double  aspirator  (Fig. 
91)  are  suitable  for  this  purpose.  Before  using  a  pair 
of  filter  tubes  a  test  for  possible  leakage  is  made  by 
placing  the  thumb  over  the  cotton  stopper  and  apply- 
ing the  aspirator;  if  the  suction  is  weak  or  absent  the 
corks  must  be  tightened  or  the  tubes  discarded.  All 
corks  should  be  tightened  and  connections  wired  and 
the  apparatus  sterilized  before  using  the  filters.  The 
collection  of  the  sample  should  take  from  1  to  2  min- 
utes per  liter. 

After  filtering  a  definite  volume  through  the  tubes 
the  sand  is  poured  into  10  c.  c.  of  sterile  water,  thor- 
oughly shaken,  and  aliquot  portions  plated  in  ordinary 
nutrient  agar,  all  plates  being  made  in  duplicate.  The 
plates  are  incubated  at  room  temperature  for  five  days, 
when  final  counts  are  made. 

Eettger's  Method, — A  new  and  improved  method 
of  enumerating  air  bacteria  has  just  been  described  by 
Rettger,^  which  commends  itself  as  the  best  method  yet  devised.     The 
method  consists  of  bubbling  a  given  quantity  of  air  through  salt  solu- 
tion.    The  bacteria  in  the  air  are  trapped  in  the  salt  solution,  which 
^Jour.  of  Med.  Res.,  June,  1910,  XXII,  3,  pp.  461-468. 


Fig.  91. — Double 
aspiratob.     , 


BACTERIA  IN  THE  AIE  719 

may  then  be  planted  in  the  usual  way  and  the  number  of  colonies 
counted. 

Air  and  Infection. — The  air  was  long  regarded  as  the  vehicle  and 
even  the  source  of  the  communicable  diseases.  Theories,  such  as  nox- 
ious effluvia,  poisonous  emanations,  and  infectious  miasmata,  gave  way 
with  the  advent  of  bacteriology.  When  the  early  classical  researches 
of  Pasteur,  Tyndall,  and  others  showed  that  bacteria  exist  in  the  air 
almost  everywhere  in  greater  or  in  lesser  numbers,  the  conclusion  was 
jumped  at  that  the  air  must  be  particularly  dangerous.  Within  recent 
years,  however,  we  have  learned  that  the  air  is  not  very  much  to  be 
feared  on  account  of  the  bacteria  it  may  carry,  except  under  certain 
occasional  circumstances.  This  change  in  our  views  during  recent  times 
is  nowhere  better  illustrated  than  in  the  relation  of  the  air  to  surgery. 
During  the  early  days  of  antiseptic  surgery  so  much  fear  was  enter- 
tained for  the  bacteria  in  the  air  that  Lister  attempted  to  neutralize 
the  danger  with  carbolic  sprays  and  other  means;  now  the  surgeon 
pays  little  heed  to  the  air  of  a  well-kept  operating  room.  Instead  he 
ties  several  layers  of  sterile  gauze  over  his  mouth  and  nostrils  and  over 
his  head  to  guard  against  particles  falling  from  these  sources. 

It  was  one  of  the  great  surprises  when  bacteriologists  demonstrated 
that  the  expired  breath  under  normal  conditions  of  respiration  is 
sterile. 

At  one  time  many,  if  not  most,  of  the  contagious  diseases  were 
believed  to  be  air-borne;  many  observations  are  on  record  purporting 
to  prove  that  contagium  may  be  carried  long  distances  through  the 
air.  With  the  increase  of  our  knowledge  concerning  the  modes  of  trans- 
mission of  infection  the  list  of  air-borne  diseases  has  steadily  dwindled. 
The  theory  is  reluctantly  given  up,  for  it  is  the  easiest  method  of  ex- 
plaining the  spread  of  the  readily  communicable  diseases.  There  are 
only  two  diseases  of  man,  viz.,  smallpox  and  measles,  which  may  pos- 
sibly be  air-borne,  in  the  sense  that  this  term  is  generally  used.  Both 
these  diseases  are  so  readily  communicable  that  the  virus  seems  to  be 
"volatile";  it  is  assumed  that  the  active  principle  is  contained  in  the 
expired  breath ;  however,  there  is  no  proof  of  this  assumption,  and  some 
evidence  to  the  contrary.  Further,  it  is  noteworthy  that  we  are  still 
ignorant  of  the  causes  and  the  precise  mode  of  entrance  of  the  con- 
tagium in  both  measles  and  smallpox.  Even  in  these  two  diseases  the 
radius  of  danger  is  much  more  limited  than  was  once  supposed  to  be 
the  case. 

The  more  the  transmission  of  the  communicable  diseases  is  studied 
the  less  the  air  is  implicated.  The  fact  that  malaria  (bad  air),  yellow 
fever,  and  other  diseases  are  conveyed  by  mosquitoes  has  robbed  the  air 
itself  of  false  accusations,  and  given  a  death  blow  to  miasms,  efl&uvia, 
^nd  intangible  theories.     Pettenkoffer  insisted  that  the  air  became  con- 


720      BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

taminated  with  poisons  that  were  generated  in  a  polluted  soil,  and  he 
believed  that  these  emanations  were  responsible  in  part  for  typhoid  fever 
and  cholera.  Some  association  between  soil,  air,  and  disease  still  per- 
sists in  both  medical  and  lay  minds,  but  with  a  more  precise  knowledge 
of  the  causes  and  modes  of  transmission  of  infections,  such  as  typhoid 
fever  and  cholera,  the  air  becomes  a  negligible  factor.  Out-of-door  air 
contains  relatively  few  bacteria ;  further,  the  dilution  is  enormous.  Most 
microorganisms  pathogenic  for  man  soon  die  when  dried  or  when  ex- 
posed to  sunlight.  Whatever  danger,  then,  resides  in  the  air,  so  far  as 
living  principles  of  disease  are  concerned,  is  found  rather  in  indoor 
air,  and  especially  in  the  air  of  badly  ventilated,  dusty,  and  crowded 
places.  Here  the  danger  may  be  either  from  the  bacteria-laden  dust  or 
from  droplet  infection.  In  a  crowded  and  stuffy  street  car,  in  a  poorly 
ventilated  office,  or  in  a  closed,  close  sickroom  it  would  be  very  easy 
for  the  microorganisms  of  diphtheria,  scarlet  fever,  whooping-cough, 
measles,  pneumonia,  influenza,  common  colds,  tuberculosis,  pneumonic 
form  of  plague,  and  other  infections  contained  in  the  secretions  from 
the  nose  and  mouth  to  be  held  in  the  air  in  sufficient  numbers  so  that 
exposed  persons  may  contract  the  disease.  This  probably  occurs  more 
frequently  than  we  are  at  present  inclined  to  admit. 

The  radius  of  danger  through  droplet  infection  is  quite  limited. 
It  is  difficult  to  conceive  that  infection  may  be  carried  long  distances 
in  the  air  and  still  be  dangerous.  My  own  experience  indicates  that 
there  is  practically  no  hazard  in  establishing  a  hospital  for  contagious 
diseases  upon  the  high  road  or  even  in  a  thickly  inhabited  part  of  the 
city.  In  fact,  the  communicable  diseases  are  not  conveyed  in  the  air 
from  ward  to  ward  or  even  from  bed  to  bed  in  well-managed  hospitals. 

Hutchinson  found  that  prodigiosus  bacilli  in  sputum  droplets  may 
be  Carried  almost  2,000  feet  when  the  temperature  is  low.  It  therefore 
seems  probable  that  diphtheria  bacilli  would  persist  longer  and  carry 
farther  in  droplet  infection  in  cold  weather  than  in  warm  weather. 
This  explanation  has  been  given  to  account  for  the  seasonal  prevalence 
of  plague,  diphtheria,  etc. 

Chapin  states  that  many  contagious  hospitals  have  been  maintained 
for  years  with  no  increase  of  the  disease  in  the  vicinity,  as,  for  instance, 
at  Boston  and  Providence,  R.  I.  At  the  Kingston  Avenue  Hospital 
in  Brooklyn  various  diseases,  as  smallpox,  measles,  scarlet  fever,  and 
diphtheria,  are  treated  in  wards  only  a  few  feet  apart,  with  no  evidence 
of  aerial  transference.  At  North  Brother's  Island  the  tuberculosis 
ward  is  only  about  25  feet  from  the  diphtheria  ward,  but  the  tuber- 
culous patients  do  not  contract  diphtheria.  A  number  of  hospitals  for 
communicable  diseases  have  recently  been  built  with  entire  disregard 
of  aerial  infection.  At  the  hospital  of  the  Pasteur  Institute,  Paris, 
the  patients  are  each  cared  for  in  a  separate  ward  opening  into  a  com- 


POISONOUS  GASES  IN  THE  AIE  721 

mon  hall.  The  same  nurses  go  from  case  to  case.  In  21/^  years  after 
it  was  opened  in  1900  there  were  treated  2,000  persons,  of  whom  524 
had  smallpox,  443  diphtheria,  126  measles,  163  erysipelas,  92  scarlet 
fevei*,  and  166  non-diphtheritic  sore  throat.  The  only  evidence  of  the 
transfer  of  infection  was  the  development  of  four  cases  of  smallpox  and 
two  of  erysipelas.  In  the  Hopital  des  Infants  Malades  in  Paris  the 
beds,  instead  of  being  in  separate  rooms,  are  separated  by  partitions. 
Of  5,017  cases  there  were  only  7  cross  infections,  6  of  measles  and  1 
of  diphtheria.  These  were  attributed  to  lapses  in  aseptic  precautions. 
Dr.  Moizard  thinks  that  this  experience  proves  that  even  measles  is  not 
air-borne.  Dr.  Grancher  in  another  Paris  hospital  has  two  wards  in 
which  there  are  no  partitions,  but  only  wire  screens  around  the  beds, 
simply  as  a  reminder  for  the  nurses.  He  also  insists  that  measles  is 
probably  not  an  air-borne  disease,  and  that  adjacent  patients  do  not 
necessarily  infect  one  another.  At  various  English  hospitals  similar 
methods  have  been  tried  with  success.^ 

While  the  air  plays  a  minor  role  in  the  spread  of  the  infections, 
bad  air  plays  an  important  part  in  reducing  vitality  and  predisposing 
to  disease.    This  will  be  discussed  presently. 


POISONOUS  GASES  IN  THE  AIR 

Some  of  the  poisonous  gases  of  the  air  come  from  natural  sources, 
as  marshes,  mines,  or  decomposing  organic  matter,  but  those  that  con- 
cern the  sanitarian  particularly  are  the  gases  which  arise  from  the 
works  of  man.  These  gases  are  carbon  monoxid,  ammoniacal  vapors, 
hydrochloric  acid,  carbon  bisulphid,  carburetted  hydrogen,  hydrogen 
sulphid,  etc. 

Carbon  Monoxid. — Carbon  monoxid  (CO)  is  a  frequent  and  serious 
cause  of  chronic  ill  health  or  acute  poisoning.  It  has  become  one  of 
the  commonest  forms  of  gas  poisoning.  It  is  usually  found  associated 
with  other  gases,  especially  from  the  incomplete  combustion  of  coal  or 
wood.  It  is  also  one  of  the  ingredients  of  illuminating  gas,  and  is  one 
of  the  constituents  of  the  gases  of  coal  mines.  Burning  charcoal  gives 
CO  in  great  abundance,  and  it  is  also  given  off  from  red  hot  cast-iron 
'^toves;  further,  it  is  found  about  lime  kilns  and  where  open  coke  fires 
and  braziers  are  used  in  confined  spaces;  also  from  iron  and  copper 
furnaces,  the  exhaust  of  gas  engines  and  from  many  manufacturing 
processes. 

The  gases  from  stoves  or  furnaces  contain  79.7  per  cent,  nitrogen, 
10  to  13  per  cent,  oxygen,  0.6  per  cent.  COg,  and  0.3  to  0.5  per  cent. 
CO  when  formed  by  the  incomplete  combustion  of  wood  or  coal  in  closed 

^Chapin:     Jour.  Am.  Med.  Assn.,  Dec.  12,  1908,  Vol.  LI,  pp.  2048-2051. 


723     BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

spaces,  that  is,  with  the  damper  closed.  Illuminating  gas  from  coal 
contains  from  6  to  10  per  cent.  CO;  from  wood  62  per  cent;  water  gas, 
30  per  cent,  and  more.  Gases  in  coal  mines  contain  from  4  to  10  per 
cent.  CO,  from  0.6  to  1  per  cent.  HgS,  and  53  per  cent.  COg.  Gases 
from  smokeless  powder  and  gun  cotton  contain  high  quantities  of  CO 
and  are  quite  dangerous. 

For  public  health  purposes  the  chief  sources  of  CO  are  leaky  gas 
fixtures,  open  coal  iires,  the  premature  closing  of  dampers  of  stoves  and 
furnaces,  or  defects  in  apparatus  fed  by  coal,  spent  gases  from  auto- 
mobiles and  explosives  in  technical  pursuits. 

Air  containing  0.4  per  cent,  of  carbon  monoxid  may,  in  one  hour, 
prove  fatal.  In  higher  concentration  a  person  may  be  overcome  at  once 
and  death  soon  ensues.  Kinnicutt  ^  states  that  breathing  an  atmos- 
phere containing  0.3  per  cent,  of  carbon  monoxid,  for  any  considerable 
period,  is  fatal,  and  the  presence  of  0.2  per  cent,  is  very  dangerous. 
Grehant  found  that  inhalation  of  an  atmosphere  containing  1  part  of 
CO  to  275  parts  of  air  was  fatal  to  a  dog,  and  that  1  in  70  killed  a 
rabbit.  Less  than  a  gram  of  CO  may  kill  a  man.  Breathing  an  atmos- 
phere containing  0.05  per  cent,  of  CO  may  cause  unpleasant,  even  serious 
symptoms.  (Oliver.)  Chronic  poisoning  with  smaller  amounts  may 
lead  to  anemia,  depression,  psychoneuroses,  and  other  symptoms. 

Carbon  monoxid  or  carbonic  oxid  is  a  colorless,  tasteless  and  prac- 
tically odorless  gas ;  it  burns  with  a  pale  blue  flame.  Its  poisonous  action 
depends  upon  the  fact  that  it  combines  with  the  hemoglobin  of  the  red 
blood  corpuscles  to  form  carbon-monoxid-hemoglobin.  This  is  a  stable 
compound  which,  therefore,  prevents  the  hemoglobin  giving  up  its  oxygen 
to  the  tissues.  When  present  in  only  small  amounts  and  for  long  periods 
of  time,  the  effects  of  CO  may  be  compensated  for  by  a  polycythemia — an 
increased  number  of  corpuscles  taking  the  place  of  those  disabled.  Car- 
bon monoxid  also  has  a  direct  destructive  action  upon  the  cells  of  the 
central  nervous  system,  producing  paralysis.  This  is  a  particularly 
dangerous  symptom  because  it  renders  a  person  suddenly  exposed 
to  large  volumes  of  the  poisonous  gas  incapable  of  escaping,  and,  unless 
rescued,  death  may  result. 

The  symptoms  depend  upon  the  percentage  of  CO  in  the  air  breathed, 
the  rapidity  of  breathing,  the  presence  of  other  gases,  and  the  age 
of  the  individual.  The  quantity  of  CO  present  in  the  air  is  of  more 
importance  than  the  length  of  exposure  to  it. 

Acute  Poisoning. — The  individual  feels  dizzy  and  complains  of 
headache,  noises  in  the  ears,  throbbing  in  the  temples,  and  the  feeling 
of  sleepiness  and  sense  of  fatigue.  .There  may  be  vomiting  and  a  sensQ 
of  oppression  at  the  chest,  palpitation,  and  an  inability  to  stand  or  walk 
straight.     Convulsions  may  or  may  not  com_e  on;  pupils  are  dilated  an4 

^Jov/r-  ^rn,  Chem.  Soc,  1900,  Vol.  XXII,  p.  14, 


POISOl^OUS  GASES  IN  THE  AIR  723 

react  slowly  to  light;  the  face  is  red;  consciousness  is  gradually  lost, 
but  owing  to  the  great  loss  of  motor  power  the  individual,  though  aware 
of  the  danger,  is  often  unable  to  escape  from  it.  In  animals  the  heart 
beat  at  first  is  slow,  while  the  blood  pressure  is  high;  in  man  the  action 
of  the  heart  is  frequently  violent  even  during  the  stupor.  When  a  man 
has  recovered  from  the  acute  effects  of  carbon  monoxid  his  life  is  still 
imperilled  for  some  days  to  come.  He  runs  the  risk  of  dying  as  late 
as  8  days  after  the  accident  and  then  he  has  still  to  face  the  risk  of  gly- 
cosuria, or  other  serious  sequelae. 

When  a  person  is  removed  from  the  poisonous  atmosphere  there  is 
slow  return  to  consciousness,  but  headache,  nausea  and  weakness  per- 
sist for  a  long  time.  In  case  of  continued  inhalation  of  the  poison 
there  is  marked  dilatation  of  the  peripheral  vessels,  causing  extensive 
red  spots  on  the  skin. 

Death  occurs  from  paralysis  of  the  respiratory  apparatus.  If  a  case 
does  not  terminate  fatally,  there  m.ay  be  serious  sequelae,  such  as 
apoplexy  followed  by  softening  of  the  brain,  or  blisters,  decubitus,  or 
paralysis  may  develop,  also  chorea,  idiocy,  or  minor  grades  of  psy- 
choneurosis. 

The  post  mortem  appearance,  following  acute  intoxication  with  car- 
bon monoxid,  show  the  following :  Features  placid,  face  and  skin  bright 
ruddy  color,  both  arterial  and  venous  blood  bright  cherry  red,  and  show 
the  spectrum  of  carbon-monoxid-hemoglobin.  The  muscles,  brain,  and 
all  organs  are  more  pink  than  usual.  Lungs  may  be  emphysematous, 
and  red  patches  may  be  observed  on  the  surface  of  the  abdominal  vis- 
cera; occasional  submucous  hemorrhages  in  the  stomach  and  intestines. 

Tests. — The  presence  of  carbon  monoxid  in  air  may  be  determined 
with  considerable  accuracy  with  a  solution  of  blood,  A  few  cubic  centi- 
meters of  normal  blood  solution  are  shaken  to  saturation  with  the  sample 
of  air.  A  dilute  blood  solution  is  yellow;  it  becomes  pink  when  treated 
with  traces  of  carbon  monoxid.  By  comparing  the  color  with  carmine 
this  method  will  serve  for  quantitative  purposes.^ 

lUummating  Gas. — Illuminating  gas  may  be  harmful  either  from  the 
products  of  its  combustion  or,  more  so,  when  the  unconsumed  gas  escapes 
in  the  household.  The  two  principal  illuminating  gases  used  are  coal 
gas  and  water  gas.'  The  poisonous  efEects  of  both  are  due  mainly  to 
the  carbon  monoxid  which  they  contain. 

Coal  gas  is  made  by  the  destructive  distillation  of  coal.    It  contains 

hydrogen,  marsh   gas,   and   carbon   monoxid,   occasionally   also   ethene, 

^  For  methods  for  determining  carbon  monoxid  and  other  gases  in  the  air, 
see:  Haldane,  J.  S.:  "Methods  of  Air  Analysis,"  J.  P.  Lippjncott  and  Co., 
1912.  Dennis:  "Gas  Analysis,"  New  York,  1913.  Melzel,  A.:  "Ueber  den 
Nachweis  des  Kohlenoxydhamoglobins,"  Verhandlungen  der  Physikal.-Med. 
Gesellschaft  zu  Wurzburg.  Neue  Folge.  Vol.  23,  p.  47.  Miiller,  F.:  "Bio- 
logische  Gasanalyse."  Handbuch  der  Biochemischen  Arbeitsmethoden.  Ill,  2. 
Berlin,   1910. 


724      BACTEEIA  AND  POISONOUS  GASES  IN  THE  AIR 

acetylene,  and  carbon  dioxid.  A  cubic  foot  of  coal  gas  completely  burned 
gives  to  the  atmosphere  about  one-half  a  cubic  foot  of  CO2  and  about 
1.34  Cubic  feet  of  water  vapor.  An  ordinary  gas  jet  burns  about  6  cubic 
feet  of  gas  per  hour,  and  thus  produces  about  3  cubic  feet  of  COg. 

Water  gas  is  made  by  blowing  a  current  of  steam  through  incan- 
descent coke  or  coal.  The  water  is  decomposed  into  hydrogen  and 
oxygen.  The  hydrogen  passes  on  and  the  oxygen  unites  with  the  carbon 
to  form  carbon  monoxid.  Water  gas  so  produced  burns  only  with  a 
pale  blue  flame.  It  is,  therefore,  enriched  in  a  carburetor  with  vapor- 
ized petroleum;  this  furnishes  the  hydrocarbons  necessary  to  give  a 
luminous  flame.  Water  gas  contains  about  30  per  cent,  of  carbon 
monoxid. 

One  of  the  most  common  sources  of  carbon  monoxid  in  the  house- 
hold is  from  illuminating  gas.  Illuminating  gas  may  pass  from  a 
broken  gas  main  through  the  soil  into  the  cellar  and  thence  permeate 
a  dwelling;  this  is  aided  by  the  suction  and  pumping  action  of  the 
heating  apparatus  in  the  cellar.  In  passing  through  the  soil  illuminat- 
ing gas  may  be  robbed  of  its  characteristic  odor,  thus  rendering  it  so 
much  more  dangerous  because  not  perceived.  The  danger  from  this 
source  is  further  increased  in  the  winter  time  and  in  cities  with  as- 
phaltum  and  concrete  pavements,  because  under  these  circumstances  the 
escape  of  gas  into  the  air  is  hindered  and  the  chance  of  more  of  it 
reaching  the  house  through  the  cellar  is  favored.  An  occasional  source 
of  CO  in  the  air  of  houses  is  through  hot-water  heaters,  using  illuminat- 
ing gas  as  fuel.  The  soot  gradually  collects  in  these  devices  and  may 
become  incandescent,  thus  furnishing  ideal  conditions  for  the  produc- 
tion of  carbon  monoxid.  In  the  arts  CO  is  formed  by  passing  water 
vapor  over  incandescent  carbon.  I  know  of  one  case  in  Washington 
where  CO  from  a  water  heater  collected  in  a  kitchenette  in  such  con- 
centration that  three  persons  were  overcome  upon  entering  the  room 
and  died. 

Most  coal  contains  sulphur,  which  appears  in  coal  gas  as  sulphuric 
acid,  which  is  irritating  and  poisonous.  Most  of  the  sulphur  compounds 
in  coal  gas  are  removed  by  processes  of  purification  during  manufac- 
ture, but,  owing  to  the  difficulty  of  complete  removal,  20  grains  of  sul- 
phur in  every  hundred  cubic  feet  are  generally  allowed  by  law.  The 
sulphur  restrictions  have  recently,  but  unwisely,  been  removed  in  Eng- 
land. In  Massachusetts  the  legal  limit  has  been  raised  to  30  grains 
per  hundred  cubic  feet.  These  changes  were  brought  about  by  the 
claims  of  gas  companies  that  it  is  much  more  difficult  than  formerly 
to  procure  coals  low  in  sulphur,  so  that  the  processes  for  the  removal  of 
the  sulphur  have  become  costly  and  burdensome. 

Illuminating  gas  is  required  by  law,  in  Massachusetts  and  in  many 
other  places,  to  be  free  from  ammonia  as  well  as  sulphuretted  hydrogen. 


POISONOUS  GASES  IN  THE  AIR 


735 


but  this  is  more  because  of  injury  to  fixtures  than  because  of  danger  to 
health. 

The  effect  of  these  carbonaceous  illuminants  is  to  elevate  the  tem- 
perature and  increase  the  moisture  of  a  room.  They  also  add  carbon 
monoxid,  carbon  dioxid,  nitric  and  nitrous  acids,  compounds  of  ammonia 
and  sulphur,  marsh  gas,  carbon  particles  (soot),  acids  of  the  fatty  group 
in  small  but  variable  amounts.  The  following  instructive  table  gives 
the  comparative  candle  power  and  also  the  gases  and  heat  produced  by 
the  usual  forms  of  illuminants : 


Quantity 
Consumed 

Candle- 
power 

Oxygen 
Removed 

Carbon 

Dioxid 

Produced 

Moisture 
Produced 

Heat 
Calories 
Pro- 
duced 

Vitia- 
tion 
Equal  to 
Adults 

Tallow  candles 

grains 

2,200 

1,740 

992 

909 

cu.  ft. 

5.5 

4.8 

3.2 

3.5 

lb.  coal 
0.3 

16 
16 
16 
16 

16 
16 

32 

50 

16 

cu.  ft. 
10.7 
9.6 
6.2 
5.9 

6.5 

5.8 

3.6 
4.1 
0.0 

cu.  ft. 
7.3 
6.5 
4.5 
4.1 

2.8 
2.6 

1.7 

1.8 

0.0 

cu.  ft. 
8.2 
6.5 
3.5 
3.3 

7.3 

6.4 

4.2 
4.7 
0.0 

1,400 
1,137 
1,030 
1,030 

1,194 
1,240 

760 

763 

37 

12.0 
11.0 

Paraffin  oil  lamp 

Kerosene  oil  lamp 

Coal   gas,    No.    5   Bats- 
wing  burner 

Coal  gas,  Argand  burner 
Coal    gas,     regenerative 

7.5 
7.0 

5.0 
4.3 

2.8 

Coal  gas,   Welsbach  in- 
candescent   

Electric    incandescent 
light 

3.0 
0.0 

Water  gas  is  cheaper  than  coal  gas,  and  is,  therefore,  preferred  by 
gas  companies.  Usually  a  mixture  of  the  two  gases  is  supplied.  Ex- 
perience shows  that  if  water  gas  is  properly  diluted,  with  coal  gas  the 
danger  is  greatly  lessened.  Illuminating  gas  containing  6  per  cent,  of 
carbon  monoxid  is  not  hazardous.  Most  cities  limit  the  amount  to  10 
per  cent.  In  1890  the  10  per  cent,  statute  was  repealed  in  Massachu- 
setts, and  it  is  since  then  that  the  marked  increase  in  illuminating  gas 
poisoning  has  Occurred.  There  were  1,231  deaths  caused  by  illuminating 
gas  in  Massachusetts  during  the  years  1886  to  1909.  About  one-half  ol 
these  deaths  were  suicidal.  This  only  represents  the  fatalities,-  and  does 
not  take  into  account  the  many  cases  of  chronic  poisoning  which  occur 
in  the  home  and  in  the  industries  where  much  illuminating  gas  is  used. 
Sedgwick  and  Schneider^  state  that  the  death  rate  from  poisoning 
by  illuminating  gas  in  Massachusetts  and  Rhode  Island  has  become 
nearly  equal  to  that_of  scarlet  fever  or  measles. 

Gas  pipes  in  a  dwelling  should  be  tested  from  time  to  time  with 
a  pressure  gage,  and  minor  leaks  from  faulty  stopcocks,  from  "rubber" 
tubing  used  for  droplights,  etc.,  should  be  carefully  searched  for  and 
corrected.  A  flaring  gas  burner  is  not  only  wasteful,  since  it  implies 
the  escape  of  unburned  gas,  but  is  also  harmful  to  health.  A  gas  jet 
should  burn  steadily  without  jumping  and  flaring. 

Methane  (CH^),  also  called  "marsh  gas,"  "fire  damp"  or  "light  car- 
Vow,  of  Infect.  Dis.,  Vol.  IX,  No.  3,   1911. 


736      BACTERIA  AND  POISONOUS  GASES  IN  THE  AIE 

buretted  hydrogen,"  is  found  in  nature  as  "natural  gas"  in  and  about 
coal  and  oil  regions.  Methane  is  very  light  compared  to  air  (specific 
gravity  0.5596),  and  forms  an  explosive  mixture  as  soon  as  it  amounts 
to  l/18th  of  the  volume  of  the  air.  Fortunately,  the  mixture  does  not 
ignite  readily,  but  is  nevertheless  the  cause  of  many  accidents  in  mines. 
The  gas  has  no  odor,  is  slightly  soluble  in  water,  burns  with  a  pale 
smokeless  flame,  yielding  watery  vapor  and  carbon  dioxid — "after  damp." 
Methane  forms  a  large  proportion  of  illuminating  gas.  It  is  usually  re- 
garded as  an  indifferent  gas,  but  it  probably  has  slight  toxic  properties. 
Haldane  found  that  5.5  per  cent,  of  methane  had  no  effect  on  man;  45 
per  cent,  causes  slower  and  deeper  breathing,  and  70  per  cent,  endangers 
life.  With  70  per  cent,  the  oxygen  is  reduced  to  only  6.3  per  cent,  and 
the  nitrogen  to  33.7  per  cent. 

Methane  is  also  given  off  in  large  quantities  from  decomposing  mat- 
ter in  swamps,  sewers  and  septic  tanks.  Methane  may  constitute  70 
to  80  per  cent,  of  the  gases  found  in  a  septic  tank.  The  gases  from  an 
Imhoff  tank  may  be  used  for  illumination  and  heating. 

The  following  table  shows  the  percentage  composition  of  illuminating 
gases,  with  the  gases  of  an  Imhoff  tank,  for  comparison : 

ILLUMINATING  CASES:  COMPOSITION  IN  PERCENTAGE ^ 

Imhoff  Tank.     Natural  Gas.     Water  Gas.     Coal  Gas. 

1.31  30  47.49 

87.75  24  38.67 

6.6  ....  1.04 

4.34  2.5  .85 

29  6.74 

.2  ..... 

1.5                  

12.5  5.21 

Other  Gases  in  the  Air. — Ammoniacal  Vapors. — Ammoniacal  vapors 
irritate  the  conjunctiva,  but  have  no  other  evident  effect  on  health 
in  the  amounts  ordinarily  found  in  the  air. 

Hydrochloric  Acid  Vapors. — Hydrochloric  acid  vapors  in  large 
quantities  are  very  irritating  to  the  conjunctiva  and  respiratory  mucous 
membranes.  In  the  alkali  manufactures  they  are  sometimes  poured 
into  the  air  in  sufficient  quantity  to  destroy  vegetation.  When  in  suffi- 
cient concentration  they  may  induce  bronchitis,  pneumonia,  and  even 
destruction  of  lung  tissue,  as  well  as  inflammation  of  the  eyes. 

Carbon  Bisulphio. — Carbon  bisulphid  is  given  off  in  the  vulcan- 
izing of  India  rubber.  It  produces  headache,  vertigo,  pains  in  the  limbs, 
formication,  sleeplessness,  nervous  depression,  and  loss  of  appetite; 
sometimes  deafness,  dyspnea,  cough,  febrile  attacks,  and  even  para- 
plegia. The  effects  seem  due  to  a  direct  anesthetic  action  on  the  nervous 
tissue. 

^Engineering  Record,  Febr.  5,  1916. 


H 

8.6 

CH4 

84.1 

CO2 

4.6 

N 

.^.1 

CO - 

0 

A 

HjS 

an, 

POISONOUS  GASES  IN  THE  AIR  727 

Hydrogen  Sulphid. — Hydrogen  sulphid  is  a  colorless,  transparent 
poisonous  gas  possessing  the  smell  of  rotten  eggs.  It  is  a  product  of  the 
putrefaction  of  organic  substances,  containing  sulphur,  and  therefore 
found  where  vegetable  or  animal  matter  is  undergoing  decay.  It  is  also 
generated  by  the  decomposition  of  organic  matter  by  anaerobic  bacteria 
in  deep  lakes  and  ponds,  tainting  the  water  in  which  it  is  soluble,  or 
coming  to  the  surface  and  tainting  the  atmosphere  where  its  presence 
is  indicated  by  the  discoloration  caused  to  neighboring  dwellings  painted 
with  white  lead.  Small  sluggish  streams  receiving  the  sewage  of  towns 
become  defiled  with  this  gas  from  which  source  it  may  be  discharged 
in  noticeable  quantities  as  it  is  carried  by  the  wind  in  different  direc- 
tions. Hydrogen  sulphid  is  formed  spontaneously  whenever  a  soluble 
sulphate  remain's  in  contact  with  decaying  organic  matter  with  deficiency 
of  air.  It  is  also  formed  directly  by  the  union  of  sulphur  and  hydrogen, 
and  indirectly  by  the  action  of  acids  on  sulphids ;  it  is  found  in  the  gases 
contained  in  some  ground  waters;  further,  in  some  mining,  smelting, 
and  other  industrial  processes;  and  in  illuminating  gas,  which  contains 
traces.  Its  intense  odor  enables  it  to  be  recognized  when  present  in 
minute  quantities,  1  part  in  10,000  being  easily  noted.  It  is  slightly 
heavier  than  air — specific  gravity,  1.1913. 

Toxic  Action. — As  a  toxic  agent,  hydrogen  sulphid  stands  between 
hydrocyanic  acid  and  carbon  monoxid.  Appreciable  quantities  in  the 
air  may  have  a  toxic  action,  which  is  due,  in  part,  to  the  formation  of 
sulf-met-hemoglobin,  but  mainly  to  a  direct  action  upon  the  nervous 
system.  The  susceptibility  of  man  to  this  gas  varies.  Its  dangerous 
nature  is  fully  recognized  in  all  chemical  laboratories.  The  effects  of 
small  amounts  are  not  well  understood;  Thackrah  could  find  no  bad 
effects.  On  the  other  hand,  Hirt  believed  it  produced  chronic  poison- 
ing, the  symptoms  being  chiefly  weakness,  depression,  anorexia,  slow 
pulse,  furred  tongue,  and  marked  pallor. 

According  to  Lehman  an  atmosphere  which  contains  0.7  to  0.8  of 
HgS  per  1,000  liters  of  air  is  dangerous  to  human  life,  while  air  con- 
taining 1  to  1.5  per  1,000  destroys  life  rapidly.  Vivian  Lewes  states 
that  man  is  killed  in  one  and  one-half  minutes  after  breathing  air 
containing  0.2  per  cent,  of  HgS.  The  sudden  death  of  men  when 
working  in  sewers-  is  sometimes  supposed  to  be  due  to  sulphuretted 
hydrogen. 

The  symptoms  caused  by  exposure  to  considerable  amounts  of  hydro- 
gen sulphid  are  redness  and  pain  of  the  eyes,  nasal  catarrh,  and  irrita- 
tion of  the  mucous  membrane  and  bronchi,  dyspnea,  cough,  rapid  beat- 
ing of  the  heart,  dizziness,  headache,  numbness,  and  cold  perspiration. 
Sudden  exposure  to  large  volumes  of  the  gas  causes  death  with  striking 
rapidity;  respiration  stops  before  the  heart.  Death  results  from  com- 
plete paralysis  of  the  central  nervous  system,  and  even  though  persons 


728      BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

are  rescued,  they  may  subsequently  succumb  from  bronchopneumonia, 
caused  by  the  irritating  nature  of  the  gas. 

Autopsies  performed  immediately  after  rapid  death  disclose  no 
changes,  not  even  in  the  blood.  In  case  of  slow  death  edema  of  the 
lungs  or  pneumonia  will  be  present,  and  the  body  has  the  characteristic 
odor  of  hydrogen  sulphid.  If  death  comes  more  slowly  asphyxia  is 
added  to  the  nervous  symptoms;  the  blood  is  dark  and  its  hemoglobin 
may  be  altered,  while  the  urine  may  contain  albumin  or  sugar. 

Hydrogen  Sulphid  in  Sewers. — Workmen  in  excavations  are  some- 
times overcome  by  H2S,  when  a  spring  containing  this  gas  is  tapped. 
Workmen  are  also  occasionally  overcome  in  the  dead  ends  of  sewers,  in 
gate  chambers  or  manholes,  and  in  these  cases  HgS  is  sometimes  said  to 
be  the  cause  of  the  accident. 

Hydrogen  sulphid  is  formed  from  sewage  by  the  breaking  down  of 
protein  and  also  by  bacterial  action  upon  inorganic  sulphates. 

In  America,  and,  so  far  as  known,  in  Europe,  there  are  no  data 
indicating  that  this  gas  ordinarily  is  present  in  measurable  quantities 
in  sewers.  At  Worcester  it  is  stated  that  careful  examination  of  large 
volumes  of  sewer  air  failed  to  show  the  presence  of  either  hydrogen  sul- 
phid or  carbon  monoxid.  At  Lawrence  it  is  also  stated  that  hydrogen 
sulphid  has  never  been  detected  in  measurable  amounts  in  the  gas  of 
any  of  the  septic  tanks. 

On  the  other  hand,  it  is  known  that  hydrogen  sulphid  makes  its 
presence  known  around  a  number  of  septic  tanks  by  the  discoloration 
of  lead  paint,  and  even  from  the  odor  of  the  gas,  as  well  as  its  disinte- 
grating effects  upon  masonry.  Mr.  W.  Thwaites  ^  records  from  0.2 
to  1.1  per  cent,  of  free  hydrogen  sulphid  per  volume  and  0.2  to  0.9  per 
cent,  of  combined  hydrogen  sulphid  in  the  sewerage  system  of  Melbourne, 
Australia.  The  sewage  of  this  city  flows  for  a  distance  of  about  18  to 
25  miles  and  is  applied  to  sewage  farms.  Hydrogen  sulphid  combines 
readily  with  basic  constituents  of  sewage  and  thus  differs  from  methane, 
nitrogen,  hydrogen,  and  other  gases  arising  from  decomposition. 

The  spent  liquors  from  tannery  wastes  sometimes  contain  calcium 
sulphid,  which  is  used  to  remove  the  hair  from  the  hides,  and  also  sul- 
phuric acid  which  is  used  in  one  of  the  processes  of  tanning.  When 
the  acid  meets  the  calcium  sulphid,  hydrogen  sulphid  is  evolved,  en- 
dangering those  in  the  sewers  or  along  the  trunk  lines.  Two  fatalities 
which  were  attributed  to  this  cause  occurred  in  Stoneham,  Massachu- 
setts. 

The  amount  of  hydrogen  sulphid  ordinarily  found  in  "sewer  gas" 
which  may  escape  into  houses  as.  a  result  of  defective  plumbing,  is  so 
small  and  so  dilute  as  to  produce  no  known  symptoms.  Hydrogen  sul- 
phid is  by  no  means  the  only  malodorous  product  of  the  decomposi- 

*  Thwaites,  W.:   Tr.  Am.  Soc.  of  Civil  Eng.,  Vol.  LIV,  Part  E,  pp.  214-30. 


SEWER  GAS  729 

tion  of  sewage;  indol,  skatol,  cadaverin,  mercaptan  and  other  ill-defiued 
products  are  even  more  offensive  than  hydrogen  sulphid. 

Sulphur  Dioxid. — Sulphur  dioxid  is  extremely  irritating  and  causes 
bronchitis.  Those  exposed  to  the  fumes  in  the  bleaching  of  cotton  and 
worsted  goods  are  frequently  sallow  and  anemic. 


SEWER  GAS 

Sewer  gas,  once  a  hygienic  bugaboo,  is  now  not  seriously  regarded 
by  sanitarians.  Sewer  gas  became  the  residual  legatee  of  Murchinson's 
pythogenic  theory,  namely,  that  typhoid  fever  was  "produced  by  emana- 
tions from  decaying  organic  matter."  People  naturally  cling  to  the 
notion  that  anything  that  smells  bad  must  be  detrimental  to  health; 
sanitarians  know  however  that  our  sense  of  smell  is  a  very  poor  sanitary 
guide. 

Sewer  "gas"  is  nothing  more  or  less  than  air  containing  the  volatile 
products  of  organic  decay  coming  from  sewers  and  drains.  Sewer  gas 
is  a  variable  mixture,  both  as  to  composition  and  concentration.  Some 
of  these  gases  are  more  or  less  poisonous,  but  not  in  the  great  dilution 
ordinarily  found  in  sewer  air.  As  a  matter  of  fact,  the  air  of  sewers  is 
ordinarily  freer  of  dust  and  bacteria  than  the  corresponding  outside 
air,  although  it  may  be  a  little  higher  in  carbon  dioxid — 10  to  30  volumes 
per  10,000.  It  is  absurd  to  regard  sewer  gas  as  the  cause  of  diphtheria, 
typhoid  fever,  scarlet  fever,  and  other  communicable  diseases.  So  far 
as  unpleasant  odors  are  concerned,  they  are  more  apt  to  come  from 
defective  drains  or  unclean  and  unventilated  house  plumbing  than  from 
a  well-constructed  sewer.  The  subject  of  putrid  odors  from  sewers  is 
a  highly  complicated  one.  Odors  are  due,  in  most  part,  to  decomposi- 
tion products,  such  as  hydrogen  sulphid,  ammonia,  indol,  skatol,  phos- 
phin,  mercaptan,  phenol,  and  various  acids,  such  as  acetic,  butyric,  vale- 
rianic and  other  compounds.  Workman  employed  in  sewers  and  about 
sewage  ordinarily  remain  hale  and  healthy.  "Sewer  gas"  as  a  rule  is 
no  more  hurtful  than  the  gases  and  odors  a  farmer  subjects  himself  to  on 
the  manure  pile. 

Bacteria  in  Sewer  Air. — When  it  was  found  that  there  are  no  danger- 
ous volatile  poisons  in  sewer  air  attention  was  focused  upon  the  bac- 
teria; however,  Nageli  as  long  ago  as  1877  showed  that  putrescent  liquids 
kept  in  the  same  sealed  vessel  for  over  two  years  did  not  infect  each 
other.  Sir  Edward  Frankland  then  showed  that  lithium  carbonate  in 
solution  did  not  contaminate  the  air,  but  that  when  effervescence  was 
produced  the  breaking  of  the  bubbles  on  the  surface  of  the  liquid  carried 
the  lithium  a  distance  of  21  feet  up  a  vertical  tube.  The  inference  was 
that  sewage  through  fermentation  or  splashing  may  send  bacteria  into 


730      BACTEEIA  AND  POISONOUS  GASES  IN  THE  AIR 

the  air.  Pumpelly  in  1881  and  others  since  have  shown  that  bacteria 
are  not  given  off  from  a  liquid  if  the  surface  remains  unbroken,  even 
though  the  air  may  blow  over  it.  In  1893  Miquel  began  a  monumental 
work  upon  bacteria  of  the  air.  He  made  routine  observations  at  the 
Montsouris  Observatory,  and  for  four  years  compared  the  bacteria  in 
the  air  of  a  Paris  street  with  the  air  of  sewers.  He  found  sewer  air  rela- 
tively pure  from  a  bacteriological  standpoint.  Carnelly  and  Haldane 
in  1877  found  fewer  bacteria  in  the  sewers  under  the  House  of  Parlia- 
ment and  other  places  than  in  the  air  of  adjacent  streets.  The  number 
of  bacteria  was  largest  in  the  best- ventilated  sewers,  because  these  brought 
the  street  bacteria  along  with  them.  Abbott  in  1894  showed  that  cul- 
tures of  B.  prodigiosus  are  not  carried  over  in  bubbles  produced  by 
natural  fermentation  (yeast  in  a  carbohydrate  medium),  but  may  be 
carried  a  short  distance  by  blowing  air  at  considerable  velocity  through 
the  culture.  He  concluded  that  the  danger  of  bacteria  being  trans- 
mitted from  sewage  into  the  air  under  ordinary  circumstances  is  prac- 
tically negligible.  In  1907  Horrocks  revived  this  question  by  placing 
B.  prodigiosus  in  the  water-closets  of  a  large  military  hospital  in  Gibral- 
tar, and  recovering  them  on  plates  suspended  on  top  of  the  soil  pipes  and 
in  manhole  openings.  His  work  gave  countenance  to  the  views  of  a  num- 
ber of  English  sanitarians,  who  maintain  the  reality  of  the  danger  from 
this  source.  Winslow  repeated  Horrocks'  experiments  in  1909,  using 
the  ordinary  sewage  of  Boston,  and  by  using  quantitative  methods  threw 
a  different  light  upon  Horrocks'  conclusions.  He  found  that  a  vigorous 
foaming  produced  very  slight  bacterial  infection  of  the  air — only  five 
prodigiosus  colonies  in  30  liters  of  air.  Further,  the  infection  always 
remained  localized.  Generally  he  found  the  air  of  house  drains  singu- 
larly free  from  bacteria.  It,  therefore,  seems  theoretically  possible,  but 
very  improbable,  that  infection  may  take  place  in  this  way.  Practically 
the  question  seems  to  have  little  importance.  Thus,  out  of  a  series 
of  examinations  of  plumbing  systems  in  actual  use,  Winslow  found 
intestinal  bacteria  only  four  times  in  200  liters  of  air,  and  these  directly 
at  the  point  of  local  splashing. 

If  there  is  any  danger  of  sewage  bacteria  coming  into  our  houses, 
it  is  rather  that  they  are  dragged  in  by  rats,  roaches,  water  bugs,  and 
other  vermin  that  use  sewers  and  drains  as  highways. 

Accidents  in  Sewers. — Workmen  who  enter  parts  of  a  sewerage  system 
are  sometimes  overcome.  Practical  sewermen  know  that  the  danger  is 
found  in  the  dead  ends,  gate  chambers,  manholes,  and  similar  places 
.  where  the  gases  can  accumulate ;  also  in  suddenly  relieving  an  obstruc- 
tion in  a  sewer,  thus  permitting  a  blast  of  gases.  There  are  no  such 
dangers  in  a  well-ventilated  sewer.  Stagnant  sewage  and  sludge,  com- 
bined with  lack  of  ventilation,  form  conditions  resembling  a  septic  tank, 
£^nd  it  is  this  combination  that  menaces  the  workers.    A  free  flow  of  sew- 


SEWER  GAS  731 

age  promotes  ventilation  and  diminishes  the  chances  of  gases  accumu- 
lating. 

The  principal  gases  given  off  from  sewers  are  methane,  carbon 
dioxid,  hydrogen,  ammonia,  and  sometimes  hydrogen  sulphid.  None 
of  these  gases  is  particularly  poisonous,  excepting  the  last.  When 
carbon  monoxid  is  found  in  sewer  air  it  does  not  come  from  the  decom- 
position of  the  sewage,  but  from  illuminating  gas  which  leaks  in.  Many 
analyses  of  sewer  air  in  many  different  places  show  that  hydrogen  sulphid 
is  usually  absent. 

The  following  table  gives  the  percentage  of  gases  found  in  settling 
tanks  in  various  cities  of  the  United  States: 

SETTLING  TANK  GASES:    PERCENTAGE  OF  CONSTITUENTS.^ 

Methane.  Nitrogen.  COj  O                 H 

Atlanta 84.1  3.1                   4.6  .4                 8.6 

Chicago 84.9  6.2                   8.6 

Urbana 81  6.1  12.3  .13 

Columbus 83.5  9.3                   8.1 

Worcester 57.7  32.5                   8.2  1.2 

Lawrence 78.9  16.3                   3.4  .5 

Manchester 73  16                     6  ....               5 

The  danger  in  entering  manholes,  gate  chambers,  or  dead  ends  of 
sewers  is  from:  (1)  illuminating  gas  which  has  leaked  in;  (2)  from 
asphyxia  on  account  of  an  accumulation  of  carbon  dioxid  and  methane; 
(3)  trade  wastes  containing  volatile  substances,  such  as  petroleum  prod- 
ucts from  garages,  dry  cleaning  establishments,  oil  works,  or  gases  caused 
by  spent  liquors  from  tanneries,  chemical  works,  etc. ;  (4)  from  poison- 
ous gases,  as  hydrogen  sulphid,  which  are  said  sometimes  to  accumulate 
in  appreciable  amounts. 

Explosions  in  sewers  are  due  to  illuminating  gas  from  leaks ;  benzin, 
naphtha,  and  gasolene  from  garages,  dyeing  and  cleaning  works,  and 
also  from  lithographic  works;  hydrocarbon  oils  used  by  railroads  to 
prevent  freezing  of  switches,  and  other  inflammable  and  explosive  sub- 
stances. The  gases  may  lae  fired  by  open  lights  carried  by  workmen,  by 
the  sparks  from  trolley  cars  or  fire  engines  passing  over  manholes,  or 
by  lightning.  The  prevention  is  constant  ventilation;  traps  for  catch 
basins,  and  furnishing  workmen  with  electric  lights  or  safety  lamps 
to  replace  ordinary  lanterns. 

ILLUSTRATIVE  CASES   OF  DEATH  ATTRIBUTED  TO  SEWER 

GAS 

Case  No.  1. — The  main  sewer  of  the  town  of  Eevere,  Mass.,  discharges 
into  the  sea  near  the  southerly  end  of  Eevere  Beach.  In  order  that 
the  sewage  might  not  discharge  on  the  incoming  tide,  a  covered  tank 

^Engineering  Record,  Febr.  5,  1915, 


732      BACTERIA  AND  POISONOUS  GASES  IN  THE  AIE 

was  built  near  the  seashore  into  which  the  sewage  collected,  and  the  tank 
was  constructed  of  such  capacity  that  the  sewage  would  not  rise  as 
fast  as  the  tide.  On  the  other  hand,  the  bottom  of  the  tank  was  some- 
what above  low  tide.  In  consequence,  the  flow  of  sewage  was  shut  off 
by  a  tide  gate  when  the  tide  was  high  for  several  hours  and  subsequently 
discharged  automatically  as  the  tide  went  down  and  the  sea  had  fallen 
below  half  tide.  Two  men  were  sent  to  clean  the  tank,  which  was  done 
by  stirring  up  the  sediment  with  a  stream  from  a  2i/^-ineh  fire  hose 
at  about  the  time  the  tank  would  discharge.  It  appears  that  trouble 
had  been  previously  experienced  by  gases  in  the  tank  chamber  at  such 
times,  and  the  man  in  charge  was  warned  of  this,  but  he  neglected  to 
warn  his  helper  whom  he  sent  down  into  the  tank ;  the  helper  was  over- 
come and  drowned.  In  the  lawsuit  the  main  question  raised  was  whether 
the  town  agents  exercised  due  care  in  the  matter,  and  the  jury  decided 
that  they  did  not,  and  awarded  full  damages  to  the  plaintiff.  No  evi- 
dence was  presented  to  show  the  character  of  the  gas  which  doubtless 
caused  the  accident  except  that  the  evidence  showed  that  the  gas  was 
odorless.  It  was  generally  believed  by  those  interested  in  the  case  that 
the  gas  was  COg. 

Case  No.  2. — On  August  6th  Henry  G.  Parker,^  an  able  and  valued 
member  of  the  staff  of  the  Engineering  Department  of  Los  Angeles,  lost 
his  life  while  inspecting  a  weir  chamber  of  the  outfall  sewer  connecting 
the  Los  Angeles  sewer  system  with  the  Pacific  Ocean.  Mr.  Parker 
and  Mr.  Derby  entered  the  chamber  to  test  the  working  of  the  gate, 
which  was  raised  and  lowered  by  means  of  a  hand-wheel  and  screw.  In 
attempting  to  raise  the  gate  they  were  overcome  with  the  foul  air  and 
were  required  to  retreat  to  the  surface  three  separate  times.  The  third 
time  Mr.  Parker  suddenly  fell  a  distance  of  twenty  feet,  and  the  body 
slipped  from  the  sluiceway  and  was  sucked  into  the  sewer  before  rescue 
could  be  accomplished.  Death  was  doubtless  due  m  large  part  to  the 
effect  of  the  gases  and  the  fall  of  twenty  feet,  and  not  to  drowning,  as 
very  little  water  was  found  in  the  lungs.  Just  what  gases  were  present 
is  not  stated. 

Case  No.  3. — During  the  pumping  out  of  a  manhole  in  Charleston, 
S.  C,  in  May,  1911,  a  small  boy  was  sent  down  to  remove  some  chips 
which  threatened  to  obstruct  the  suction  pipe.  He  succumbed  almost 
immediately.  One  of  the  workmen  went  down  to  rescue  him;  he  also 
became  unconscious.  A  third  party,  with  a  rope  tied  around  him,  went 
to  the  rescue  of  the  two.  When  taken  from  the  manhole,  the  small  boy 
was  dead,  and  the  second  man  was  unconscious.  The  symptoms  reported 
by  Dr.  Jager  and  Dr.  Jerdey  were  those  of  hydrogen  sulphid  poisoning. 
A  qualitative  analysis  of  the  air  of  the  manhole  made  at  a  later  time 
showed  the  presence  of  hydrogen  sulphid,  and  no  appreciable  quantities 

^  Engmeering  Record,  Aug.  28,  1909,  LX,  9,  p.  252. 


SEWER  GAS  733 

of  carbon  monoxid.  It  is  assumed  in  this  case  that  the  hydrogen  sulphid 
in  the  manhole  probably  accumulated  and  became  concentrated  in  the 
bottom  of  the  manhole,  although  it  was  recognized  that  other  gases 
may  have  contributed  to  the  gravity  of  the  condition. 

Case  No.  4- — A  laborer  went  into  an  intercepting  sewer  on  Market 
Street  in  Lynn,  Mass.,  to  inspect  it,  and  after  he  had  proceeded  into  the 
sewer  about  250  feet  his  lantern  exploded,  covering  him  with  blazing 
oil.  The  cause  was  assumed  to  be  illuminating  gas  that  had  leaked  into 
the  sewer  from  some  unknown  place.  The  man  had  his  hair  singed  and 
his  face  badly  blistered,  and  was  partly  overcome.  The  sewer  was  not 
ventilated,  nearby  manholes  having  been  closed. 

Prevention  of  Accidents  in  Sewers. — To  prevent  accidents  in  man- 
holes, and  other  parts  of  the  system  where  sewer  gases  may  collect, 
it  is  advisable  for  men  always  to  work  in  pairs,  and  to  be  ready  with 
rope,  tackle  and  tripod  in  case  of  emergency.  Accidents  may  be  pre- 
vented by  clearing  out  cul-de-sacs  where  sewer  gases  are  likely  to  collect, 
before  the  men  enter  such  places.  This  may  be  done  by  an  air  blast, 
but  as  this  is  usually  not  at  hand  the  same  purpose  may  be  accomplished 
by  a  water  spray  having  a  good  head  and  volume.  This  stirs  up  the  air 
and  ventilates  the  pocket. 

Other  precautions  to  determine  the  presence  of  dangerous  or  irre- 
spirable  gases  consist  in  lowering  a  candle,  a  safety  lamp,  or  small 
animals  (canary  or  mouse)  in  a  cage. 

Ventilation  of  Sewers. — Sewers  cannot  be  constructed  airtight  on 
account  of  the  numerous  openings  into  them.  The  tension  of  the  air 
in  sewers  is  generally  not  very  different  from  that  of  the  atmosphere 
outside.  The  movement  of  the  air  is  generally  in  the  direction  of  the 
flow  of  the  current.  The  simplest  plan  of  ventilation  is  by  means  of 
a  shaft  from  the  top  of  the  sewer  to  the  surface  of  the  street  or  road 
above,  where  the  opening  of  the  shaft  should  be  covered  by  an  iron 
grating.  These  openings  are  usually  placed  at  intervals  of  100  yards 
or  so.  This  system,  which  is  in  common  use,  has  been  much  criticized, 
mainly  on  account  of  the  fact  that  the  objectionable  gases  are  discharged 
more  or  less  immediately  under  the  noses  of  passers-by.  To  meet  this 
objection  it  has  been  proposed,  and  actually  come  about  in  some  places, 
to  locate  tall  iron  shafts  at  suitable  intervals  to  permit  the  discharge 
of  air  and  gases  at  a  level  well  above  the  roofs  of  houses.  As  a  mat- 
ter of  fact,  if  sewers  are  well  constructed,  have  sufficient  fall  and  flow 
of  water,  there  will  be  no  accumulation  of  foul  gases.  One  of  the  main 
causes  of  decomposition  is  due  to  dead  ends.  These  should  not  be 
tolerated  by  the  engineer  in  charge  of  the  sewage  department.  Recently 
an  agitation  has  been  started  to  solve  this  question  of  sewage  ventilation 
by  advocating  the  abolition  of  the  intercepting  traps  on  the  house  drains 
between  the  sewer  and  the  house,  thus  converting  every  house  drain 


734      BACTERIA  AND  POISONOUS  GASES  IN  THE  AIR 

and  every  soil  pipe  into  so  many  sewer  ventilators.  There  are  many 
objections  to  this  plan,  as  it  would  destroy  the  drain  isolation  between 
each  house,  which  is  now  possible  from  the  sewer,  and  from  the  neigh- 
boring houses  of  the  district. 


CHAPTT^E  V 
FEESH  AND  VITIATED  AIR 

THE  BENEFITS  OF  FRESH  AIR 

Fresh  air  is  nature's  tonic.  It  stimulates  digestion,  promotes  as- 
similation, improves  metabolism,  strengthens  the  nervous  system,  and 
increases  our  resistance  against  some  diseases.  It  is  a  common  ex- 
perience that  fresh  air  gives  us  a  general  feeling  of  well-being.  Much 
of  the  benefit  of  an  outdoor  life  comes  also  from  the  exercise,  diversion, 
sunshine,  and  other  factors.  The  stimulating  effect  of  outdoor  air 
varies  considerably  with  the  temperature  and  movements  of  the  air. 
Cold  air  is  especially  stimulating,  and  much  of  the  good  of  sleeping 
out  of  doors  is  perhaps  secondarily  due  to  the  tonic  action  of  cold. 
Sleeping  out  of  doors  or  with  open  windows  atones  for  much  bad  air 
during  the  daytime.  However,  the  good  results  of  fresh  air  may  be 
neutralized  by  undue  exposure  to  cold,  especially  in  the  young,  the  aged, 
and  the  feeble — or  even  in  robust  individuals  not  properly  protected. 

"We  may  write  and  talk  as  much  as  we  please  about  the  horrors 
of  bad  air  and  the  importance  of  fresh  air,  but  we  should  never  in- 
duce people  to  sit  in  cold  drafts  and  shiver  for  the  sake  of  pure  air, 
a.nd,  in  fact,  we  would  not  want  to  do  it  ourselves"  (Macfie).  Extremes 
in  this  as  in  all  matters  hygienic  are  to  be  avoided.  It  is  important  that 
those  who  sleep  out  of  doors  or  sit  out  should  be  warmly  clad  and 
sufficiently  fed,    . 

THE  EFFECTS  OF   VITIATED  AIR 

The  effects  produced  by  an  atmosphere  vitiated  by  the  breath  and 
other  exhalations  from  human  beings  may  be  divided  into  acute  and 
chronic.  The  acute  effects  are  usually  lassitude,  headache,  vertigo, 
nausea,  vomiting,  and  even  collapse.  In  extreme  cases  death  may  en- 
sue. The  chronic  effects,  so  far  as  is  known,  include  anemia,  debility, 
and  disturbances  of  digestion.  Prolonged  exposure  to  vitiated  atmos- 
pheres also  influences  nutrition  and  metabolism,  depresses  vitality,  and 
lowers  the  resistance  to  certain  infections,  especially  to  the  pyogenic 

735 


736  FRESH  AND  VITIATED  AIR 

cocci,  the  tubercle  bacillus,  the  pneumococcus,  and  to  the  microorgan- 
isms causing  common  colds.  It  is  often  difficult,  especially  in  the  poorer 
classes,  to  know  how  much  is  due  to  bad  air  and  how  much  to  crowding, 
poor  food,  overwork,  loss  of  sleep  and  rest,  worry,  and  other  inflictions 
of  poverty.  There  is  plenty  of  evidence  to  show  that  men  living  in  insuffi- 
ciently ventilated  barracks  and  other  habitations  have  a  high  death  rate. 
The  lower  animals  under  like  conditions  in  crowded  and  poorly  venti- 
lated stables  also  have  a  high  mortality.  The  statistical  evidence  of 
the  English  Barrack  and  Hospital  Commission,  published  as  long  ago  as 
1861,  shows  that  men  living  a  considerable  portion  of  their  time  in 
badly  ventilated  rooms  have  a  higher  death  rate  than  those  having  well- 
ventilated  rooms,  other  conditions  being  about  the  same. 

The  high  morbidity  and  mortality  in  crowded  places  are  due,  in  part 
at  least,  to  the  favorable  conditions  for  the  spread  of  the  communicable 
diseases,  and  must  not  be  laid  entirely  to  the  effects  of  vitiated  atmos- 
pheres. 

Some  Extreme  Cases. — The  acute  and  fatal  effects  caused  by  breath- 
ing a  seriously  vitiated  atmosphere,  under  unusually  severe  conditions, 
are  well  illustrated  by  the  three  following  instances: 

After  the  battle  of  Austerlitz  300  Austrian  prisoners  were  shut  into 
a  prison  in  a  small  cellar,  and  360  were  killed  by  the  impure  air  in  a  few 
hours. 

In  the  tragedy  known  as  the  Black  Hole  of  Calcutta,  the  military 
prison  of  Fort  William,  January  18,  1756,  146  adults  were  shut  into  a 
room  only  18  feet  square  and  with  but  two  small  windows  on  one  side 
to  ventilate  it.  They  were  shut  in  at  8  P.  M.,  and  within  an  hour  some 
were  dead,  and  when  the  door  was  opened  at  6.20  next  morning  only 
33  were  found  to  be  alive.  One  of  the  survivors  gives  the  following 
description  of  the  horrors  of  the  night:  "At  this  period  so  strong  a 
flavor  came  from  the  prison  that  I  was  not  able  to  turn  my  head  that 
way  for  more  than  a  few  seconds  at  a  time.  Everybody  except  those 
at  the  windows  now  grew  outrageous  and  many  delirious.  By  eleven 
o'clock  greater  numbers  were  dead  or  dying,  and  those  living  were  in  an 
outrageous  delirium  and  others  quite  ungovernable.  A  steam  now  arose 
from  the  living  and  the  dead,  which  most  awfully  affected  those  who 
were  still  alive.  At  six  o'clock  next  morning  it  came  to  the  ears  of  the 
Indian  governor  the  havoc  death  had  made  in  this  fearful  place,  and  he 
ordered  their  release.  At  6.30  there  came  out  of  this  living  grave  23  half- 
dead  creatures,  being  all  that  remained  of  the  146  souls  who  had  entered 
the  Black  Hole  prison,  and  these  were  in  such  a  condition  that  it  seemed 
very  doubtful  whether  they  would  see  the  morning  of  another  day.  Many 
of  the  survivors  developed  putrid  fever  and  boils.  The  remaining  23 
were  poisoned  by  exhalations  from  their  own  lungs  and  bodies." 

An  almost  equally  terrible  tragedy  took  place  on  the  steamer  Lon- 


THE  EFFECTS  OF  VITIATED  AIR  737 

donderry,  going  between  Sligo  and  Liverpool.  The  episode  is  thus 
described  by  Gr.  Henry  Lewes  ("Physiology  of  Common  Life")  : 

"On  Friday,  December  2,  1848,  she  left  for  Liverpool  with  two  hun- 
dred passengers  on  board,  mostly  emigrants.  Stormy  weather  came  on, 
and  the  captain  ordered  every  one  below.  The  cabin  for  the  steerage 
passengers  was  only  18  feet  long,  11  feet  wide,  and  7  feet  high.  Into 
this  small  space  the  passengers  were  crowded;  they  would  only  have 
suffered  inconvenience  if  the  hatches  had  been  left  open ;  but  the  captain 
ordered  these  to  be  closed,  and — for  some  reason  not  explained — ^he 
ordered  a  tarpaulin  to  be  thrown  over  the  entrance  to  the  cabin  and 
fastened  down.  The  wretched  passengers  were  now  condemned  to 
breathe  over  and  over  again  the  same  air.  This  soon  became  intolerable. 
Then  occurred  a  horrible  scene  of  frenzy  and  violence,  amid  the  groans 
of  the  expiring  and  the  curses  of  the  more  robust;  this  was  stopped 
only  by  one  of  the  men  contriving  to  force  his  way  on  deck,  and  to 
alarm  the  mate,  who  was  called  to  a  fearful  spectacle:  seventy-two  were 
already  dead,  and  many  were  dying;  their  bodies  were  convulsed,  the 
blood  starting  from  their  eyes,  nostrils,  and  ears." 

The  foregoing  instances  are  exceptional,  and  for  practical  purposes 
may  be  regarded  simply  as  the  results  of  suffocation.  The  usual  con- 
ditions never  approach  such  extremes,  but  are,  nevertheless,  important, 
for  they  may  be  serious.  We  must  first  consider  the  question  why  an 
atmosphere  vitiated  by  the  presence  of  human  beings  produces  ill  effects. 

Three  explanations  have  been  offered :  ( 1 )  increase  of  carbon  dioxid 
and  diminution  of  oxygen;  (2)  poisons  in  the  expired  breath;  (3) 
physical  changes  of  the  air.  Each  of  these  explanations  will  be  consid- 
ered separately. 

The  Effects  of  Increased  Carbon  Dioxid  and  Diminished  Oxyg^en. — ■ 
According  to  the  older  theories,  the  sensations  of  discomfort,  arising 
in  inclosed  places,  had  their  origin  either  in  an  excess  of  carbon  dioxid 
or  an  insufficiency  of  oxygen.  Thus,  in  the  early  experiments  of  Claude 
Bernard  (1857)  animals  were  confined  in  atmospheric  air  and  in  mix- 
tures both  richer  and  poorer  in  oxygen  than  atmospheric  air.  He  ex- 
plained that  poisonous  effects  of  carbonic  acid  when  respired  to  be  due 
to  the  fact  that  it  deprived  the  animal  of  oxygen.  Similar  results  were 
reported  by  Valentin  and  by  Paul  Bert.  Richardson  in  1860-61  found 
that  a  temperature  much  higher  or  lower  than  20°  C.  had  the  effect  of 
shortening  very  considerably  the  lives  of  animals  confined  in  an  unventi- 
lated  jar.  Pettenkoffer  in  1860-63  cast  the  first  serious  doubt  on  the 
correctness  of  these  theories.  He  believed  that  the  symptoms  observed 
in  crowded,  ill-ventilated  places  were  not  produced  by  the  excess  of  car- 
bonic acid  nor  by  a  decrease  in  the  proportion  of  oxygen  in  the  air.  He 
further  did  not  believe  that  the  impure  air  of  dwellings  was  directly 
capable  of  originating  specific  diseases,  or  that  it  was  really  a  poison 
25 


738  FEESH  AND  VITIATED  AIR 

in  the  ordinary  sense  of  the  term,  but  that  it  diminished  the  resistance 
on  the  part  of  those  continually  breathing  such  air, 

Hermans  ^  showed  that  an  atmosphere  containing  only  15  per  cent, 
of  oxygen  and  as  much  as  2  to  4  per  cent,  of  carbon  dioxid  may  not 
be  harmful.  On  removing  the  carbon  dioxid  there  was  no  great  discom- 
fort, even  when  the  oxygen  was  reduced  to  10  per  cent.  The  air  of  cer- 
tain breweries  examined  by  Lehmann  ^  contained  1.5  to  3.5  per  cent, 
of  carbon  dioxid,  and  men  worked  continuously  in  this  for  years  with- 
out any  ill  effects.  The  COg  occasionally  rose  to  6  and  even  10  per  cent., 
but  this  amount  produces  panting  and  distress.  It  is  now  generally 
admitted,  upon  the  testimony  of  numjerous  experimenters,  that  an  atmos- 
phere containing  as  much  as  3  per  cent,  of  carbon  dioxid  and  as  little 
as  15  per  cent,  of  oxygen  has  no  toxic  effects  and  produces  no  disturb- 
ing symptoms.  In  the  most  poorly  ventilated  rooms  the  carbon  dioxid 
never  reaches  this  amount,  especially  when  produced  by  respiration  alone. 
It  is  unusual  to  find  0.5  per  cent.  In  the  most  crowded  rooms  the  oxygen 
rarely  reaches  20  per  cent.  It  is,  therefore,  plain  that  we  must  look 
to  other  causes  for  the  effects  of  vitiated  air.  (See  also  pages  669  and 
663.) 

Poisons  in  the  Expired  Breath. — In  1863  Hammond  believed  he 
demonstrated  the  presence  of  organic  matter,  because  when  vitiated 
air  is  passed  through  potassium  permanganate,  it  decolorizes  that  strong 
oxidizing  agent.  Hammond  confined  a  mouse  under  a  jar  in  which  the 
CO2  was  taken  up  by  baryta  water  as  fast  as  it  was  formed  and  the 
moisture  absorbed  by  calcium  chlorid.  Nevertheless,  the  mouse  died  in 
40  minutes.  The  observation  was  repeated  a  number  of  times,  and 
death  ensued  invariably  in  less  than  one  hour.  Brown-Sequard  and 
D'Arsonval  in  1888-9  claimed  to  be  the  first  to  demonstrate  poisonous 
bodies  in  the  expired  breath.  They  condensed  the  moisture  in  the  ex- 
haled breath,  which  was  injected  into  the  veins  of  rabbits.  Death  usually 
took  place  in  a  few  days,  sometimes  in  a  few  weeks.  They  believed 
from  this  that  they  had  discovered  a  volatile  organic  poison  of  the  nature 
of  an  alkaloid,  similar  to  Brieger's  ptomains.  These  experiments  were 
repeated  with  variable  results,  but  in  1889  they  reported  ingenious  ex- 
periments in  which  they  obtained  additional  evidence  in  support  of  their 
former  statements.  Eabbits  were  confined  in  a  series  of  jars  connected 
with  rubber  tubing,  permitting  a  constant  current  of  air  to  be  passed. 
The  animal  in  the  last  jar  received  the  air  from  the  lungs  of  the  animals 
in  the  other  jars.  This  animal  died  after  an  interval  of  some  hours, 
and  the  animal  in  the  next  jar  was  the  next  to  die.  The  first  and  second 
animals   usually   remained    alive.      When    absorption    tubes    containing, 

*  Hermans :  "Ausschaltung  organischer  Substanzen  durch  den  Menschen," 
Archiv  f.  Hyg.,  1883,  I,  1. 

*  Lehmann :  "Untersuchung  iiber  die  langdauernde  Wirkung  mittlerer  Kohl- 
ensauredoscn  auf  den  Menschen,"  Arch.  f.  Hyg.,  1899,  XXXIV,  335. 


THE  EFFECTS  OF  VITIATED  AIK  739 

concentrated  sulphuric  acid  were  placed  between  the  last  two  jars,  the 
animal  in  the  last  Jar  remained  alive  while  the  one  in  the  jar  just 
before  was  the  first  to  die.  These  results  confirmed  their  belief  in  the 
existence  of  a  volatile  poison  absorbed  by  the  sulphuric  acid.  Haldane 
and  Smith  repeated  the  experiments  of  Brown-Sequard  and  D'Arsonval, 
using  five  bottled  mice.  They  continued  the  exposure  for  53  hours  with- 
out ill  affects  to  the  mice.  Beu  in  1893  also  repeated  these  experiments, 
and  came  to  the  conclusion  that  acute  poisoning  through  the  organic 
matters  contained  in  the  expired  air  was  not  possible,  and  that  the 
death  of  the  animals  was  due  to  changes  of  temperature  and  accumu- 
lation of  moisture  in  the  jars.  Eauer  in  1893,  also  Liibberd  and  Peters, 
concluded  from  similar  experiments  that  there  are  no  organic  poisons 
in  the  expired  air.  In  fact,  Merkel  stands  almost  the  only  sponsor  for 
the  correctness  of  the  conclusions  of  Brown-Sequard  and  D'Arsonval, 
and  with  some  slight  changes  of  technic  he  was  unable  to  get  uniform 
results. 

Lehmann  and  Jessen  in  1890  collected  from  15  to  20  c.  c.  of  con- 
densed fluid  per  hour  from  the  breath  of  a  person  exhaling  through 
a  glass  spiral  laid  in  ice.  This  fluid  was  always  clear,  odorless,  neutral 
in  reaction,  and  contained  slight  traces  of  ammonia  with  good  teeth; 
more  with  poor  teeth.  Inoculation  of  this  condensed  fluid  into  animals 
gave  negative  results.  Many  other  experiments,  including  von  Hoffman- 
Wellenhof,  Lehmann  and  Jessen,  Haldane  and  Smith,  Billings,  Weir 
Mitchell,  and  Bergey,  have  shown  that  the  fluid  condensed  from  the 
breath  is  no  more  toxic  than  distilled  water,  when  injected  into  animals. 
This  has  strengthened  the  general  belief  that  poisonous  bodies  are  not 
present. 

In  1894  Brown-Sequard  and  Davis  reported  further  experiments  in 
which  they  inoculated  over  one  hundred  animals  with  the  condensed 
fluid  of  respiration,  and  not  only  confirmed  their  former  statements, 
but  were  unable  to  understand  the  failure  of  other  experimenters,  and 
emphatically  reaffirmed  that  the  breath  contains  a  volatile  poison  and 
that  the  death  of  animals  under  experimental  conditions  is  not  due  to 
an  excess  of  carbon  dioxid  nor  a  deficiency  of  oxygen.  These  experiments 
were  repeated  by  Billings,  Mitchell,  and  Bergey  ^  in  1895,  who  came  to 
the  conclusion  that  the  ill  effects  of  vitiated  atmosphere  depend  almost 
entirely  upon  increased  temperature  and  moisture,  and  not  on  an  ex- 
cess of  carbon  dioxid  or  bacteria  or  dust  of  any  kind.  They  admit 
that  the  cause  of  the  musty  odor  in  unventilated  rooms  is  unknown. 

In  addition  to  reducing  potassium  permanganate,  it  has  been  shown 
that  the  breath  contains  traces  of  ammonia  and  traces  of  hydrochloric 
acid.     These  have  their  origin  in  decaying  teeth  and  decomposing  par- 

*  Published  by  Smithsonian  Institution,  1895.  Contains  a  summary  of  the 
literature  to  date,  with  references  to  authorities. 


740  FRESH  AND  VITIATED  AIE 

tides  of  food  or  other  putrefactive  or  pathological  changes  occurring 
in  the  upper  respiratory  passages.  The  ammonia  and  hydrochloric 
acid  exist  in  such  small  quantities  that  they  have  no  practical  bearing 
upon  the  question  under  consideration. 

Weichardt  ^  calls  attention  to  the  fact  that  putrefactive  processes 
go  on  in  the  excretory  products  of  the  respiratory  tract,  especially  in 
older  persons.  He  states  that  the  bronchial  mucus  of  corpses  contains 
a  poison  resembling  kenotoxin  (the  toxin  of  fatigue).  When  injected 
into  laboratory  animals  it  produces  a  lowering  of  temperature,  a  slow- 
ing of  respiration,  and  death.  According  to  Weichardt,  fluids  condensed 
from  the  expired  air  and  then  concentrated,  when  injected  into  mice, 
produce  like  results.  This  investigator  also  evaporated  some  of  the 
condensed  moisture  from  the  expired  breath  and  obtained  a  weighable 
residue  (9  milligrams  from  10  c.  c).  This  he  regards  as  partly  or- 
ganic matter.  As  further  proof  that  the  organic  matter  in  the  expired 
breath  is  active,  he  obtained  from  the  expired  breath  of  a  tired  old  man 
the  condensed  fluid  which  he  then  concentrated.  This  concentrated 
fluid  has  a  distinct  inhibitory  effect  upon  the  oxidizing  power  of  the 
ferments  in  blood,  as  shown  by  the  guaiac  indicator.  Also  by  means 
of  the  epiphanin  reaction  Weichardt  considers  that  he  has  demonstrated 
protein-split  products  in  the  vitiated  air  of  a  room.  He  concludes  that 
substances  having  such  important  biological  power  should  not  be  longer 
overlooked.  These  results  lack  confirmation,  and  the  methods  are 
open  to  criticism. 

Eosenau  and  Amoss  ^  demonstrated  the  presence  of  minute  traces 
of  non-poisonous  protein  matter  in  the  expired  breath  through  the 
reaction  of  anaphylaxis.  The  first  injection  into  guinea-pigs  of  the 
fluid,  obtained  by  condensing  the  moisture  of  expiration,  is  harmless, 
but  the  animals  become  sensitized,  so  that  they  react  to  an  injection  of 
human  blood  serum  after  an  interval  of  several  weeks.  These  results 
lack  confirmation,  in  fact  Weisman  and  also  Winslow  obtained  nega- 
tive results.  In  any  event  there  is  no  evidence  that  the  expired  breath 
contains  a  poisonous  substance. 

Physical  Changes  in  the  Air. — Owing  to  the  failure  of  chemistry  to 
demonstrate  the  cause  of  the  ill  effects  produced  by  a  vitiated  atmos- 
phere, attention  has  recently  been  focused  upon  the  physical  changes, 
such  as  the  increase  in  temperature,  increase  in  humidity,  and  the  still- 
ness of  the  air  in  a  poorly  ventilated  room.  Important  experiments  were 
carried  out  about  five  years  ago  in  the  Institute  of  Hygiene  in  Breslau 
by  Heymann,  Paul,  and  Erclentz.     Fliigge,^  who  was  then  the  director 

*  Weichardt :  "Ueber  Eiweif sspaltprodukte  in  der  Ausatemluf t,"  Arch.  f. 
Hug.,  1911,  74  Bd.,  Heft  5. 

'  "Organic  Matters  in  the  Expired  Breath,"  Jova-.  of  Med.  Research,  Vol. 
XXV,  No.   1,  Sept..  1911,  p.  35. 

^Fliiggc;  Ztschr.  f.  flyg.,  1905,  XLIX,  363.  Crowder:  Archives  of  In- 
ternal ^edipiri^,  Jan.,  1911,  Vol.  VII,  pp.  85-133.     Contains  an  admirable  sum- 


THE  EFFECTS  OF  VITIATED  AIR  741 

of  the  institute,  has  admirably  summarized  and  interpreted  the  results 
as  follows : 

Paul  placed  healthy  individuals  in  a  cabinet  of  3  cubic  meters' 
capacity,  where  they  were  kept  for  a  variable  time  up  to  four  hours, 
and  until  the  carbon  dioxid  had  risen  to  100  or  150  parts  in  10,000 — 
an  accumulation  of  gaseous  excretion  practically  never  developed  un- 
der ordinary  conditions.  In  these  experiments  no  symptoms  of  illness 
or  discomfort  developed  so  long  as  the  temperature  and  moisture  were 
kept  low.  Tests  of  the  psychic  fatigue  of  these  individuals  by  means 
of  the  esthesiometer  and  ergograph,  or  by  means  of  computations,  gave 
negative  results  throughout,  under  similar  conditions  of  temperature  and 
moisture.  Tests  in  a  crowded  schoolroom  were  similarly  negative.  Er-. 
clentz  made  the  same  observations  on  diseased  persons.  Those  suffering 
from  emphysema,  heart  diseases,  kidney  diseases,  etc.,  with  the  excep- 
tion of  a  few  peculiarly  susceptible  anemic  and  scrofulous  school  chil- 
dren, bore  the  highly  vitiated  air  for  hours  without  any  evidence  of 
bodily  or  mental  depression. 

The  results  were  very  different,  however,  when  the  temperature  and 
moisture  of  the  air  of  the  cabinet  were  allowed  to  increase.  At  80°  F. 
with  moderate  humidity,  or  at  from  70°  to  73.5°  F.  with  high  humid- 
ity, practically  all  persons  began  to  show  depression,  headache,  dizziness, 
or  a  tendency  to  nausea.  The  susceptibility  was  not  alike  for  all. 
School  children  reacted  slightly  and  emphysematics  slightly,  while  those 
with  heart  troubles  were  most  susceptible.  By  means  of  certain  ob- 
jective signs  of  heat  stagnation — the  surface  temperature  of  the  fore- 
head and  the  temperature  and  moisture  of  the  clothed  parts  of  the 
body — it  was  determined  that  subjective  symptoms  appeared  only  when 
the  surface  temperature  reached  a  certain  height.  This  was,  for  healthy 
people,  93°  F.  to  95°  F.  on  the  forehead;  for  the  more  susceptible  and 
diseased,  89.5°  to  91.5°;  and  with  the  moisture  of  the  skin  increased 
by  20  or  30  per  cent.  Under  these  conditions  the  normal  dissipation 
of  body  heat  is  interfered  with,  and  it  is  under  these  conditions  that 
symptoms  appear  which  are  in  every  way  similar  to  those  developed 
in  overfilled  and  "stuffy"  rooms. 

Now,  when  these  people  in  the  cabinet  suffering  from  such  symp- 
toms were  allowed  ta  breathe  the  fresh  outside  air  through  a  tube,  such 
air  being  raised  to  the  temperature  and  relative  humidity  of  that  within, 
it  gave  them  no  relief  whatever;  nor  did  the  internal  air  produce  any 
symptoms  when  breathed  through  a  tube  by  one  outside  of  the  cabinet. 
But  the  symptoms  of  discomfort  and  illness  experienced  by  the  person 
within  could  be  almost  immediately  relieved  either  by  drying  the  air 
of  the  cabinet  or  by  cooling  it,  or  by  putting  it  in  rapid  motion  by  means 

mary  and  references  to  the  literature  upon  the  subject.  More  recent  references 
will  be  found  in  Crowder's  article,  Arch,  of  hit.  Med.,  Oct.,  1913,  p.  420. 


74S  FRESH  AND  VITIATED  AIE 

of  a  fan,  without  any  ehemical  change  hc'mg  made  in  the  air.  The 
effect  of  these  measures  is  simply  by  purely  mechanical  means  to  enable 
the  body  to  throw  off  its  heat  more  rapidly,  and  thereby  all  symptoms 
disappear;  heat  stagnation  is  the  cause  of  the  discomfort. 

From  the  long  series  of  experiments,  carried  out  with  great  care  as 
to  all  the  details  of  observation  and  control,  it  is  concluded  that  all  of 
the  symptoms  arising  in  the  so-called  vitiated  atmosphere  of  crowded 
rooms  are  dependent  on  heat  stagnation  in  the  body,  and  that  the  ther- 
mic conditions  of  the  atmosphere^  its  moisture,  and  its  stillness  are 
responsible  for  the  effects.  To  change  any  one  of  these  elements  is  to 
change  the  rapidity  of  the  loss  of  heat.  If  the  change  is  such  as  to 
increase  this  loss,  comfort  is  restored.  It  is  also  considered  proved 
beyond  any  reasonable  doubt,  by  their  own  as  well  as  by  previous  re- 
search, that  there  is  no  gaseous  excretion  into  the  surrounding  air,  either 
from  the  breath  or  from  other  sources,  deserving  of  the  name  of  poison. 

Angelici,^  working  independently  at  about  the  same  time,  concurs  in 
these  opinions ;  and  Eeichenbach  and  Heymann  ^  later  determined  that 
objective  evidence  of  heat  stagnation  in  the  body  always  precedes  the 
development  of  subjective  symptoms  of  discomfort  under  natural  con- 
ditions, in  the  same  way  that  it  does  under  the  artificial  conditions  of 
the  cabinet. 

Leonard  Hill  ^  of  England  also  has  confirmed  these  general  results 
and  conclusions. 

The  New  York  Commission  on  Ventilation  *  found  that  the  power 
to  do  mental  or  physical  work,  measured  by  the  quantity  and  quality 
of  the  product  by  subjects  doing  their  utmost,  is  not  at  all  diminished 
by  a  room  temperature  of  86°  F.,  with  80  per  cent,  relative  humidity,  but 
the  inclination  to  do  physical  work  is  diminished  by  high  temperatures. 
The  only  effect  of  stagnant  air,  even  when  it  contains  twenty  or  more 
parts  of  carbon  dioxid,  is  sliglitly  to  diminish  the  appetite. 

The  experiments  seem  to  indicate  that  over-heated  rooms  are  not 
only  uncomfortable,  but  produce  well  marked  effects  upon  the  heat  regu- 
lating and  circulatory  systems  of  the  body  and  materially  reduce  the 
inclination  of  occupants  to  do  physical  work.  The  most  important 
effects  of  even  a  slightly  elevated  room  temperature,  such  as  75°  F., 
are  sufficiently  clear  and  important  to  warrant  careful  precautions 
against  over-heating. 

Reinspiration  of  Expired  Air. — By  this  phenomenon  is  meant  the 

^Angelici:  Quoted  by  Eeichenbach  and  Heymann,  Ztschr.  f.  Hyg.,  1907, 
LVII,  23. 

*  Eeichenbach  and  Heymann :  "Untersuchungen  liber  die  Wirkungen  klima- 
tischer  Factoren  auf  den  Menschen,"  Ztschr.  f.  Hyg.,  1907,  LVII,  23. 

^Hill,  Leonard,  Rowland,  E.  A.,  and  Walker,  H.  E.:  "The  Relative  Influ- 
ence of  the  Heat  and  Chemical  Impurity  of  Close  Air,"  London  Hosp.  Med.  Col., 
Journal  of  Physiology,  XLI,   1911. 

^Amer.  Jour,  of  Public  Health,  Vol.  V,  February,  1915,  No.  2,  p.  85. 


THE  EFFECTS  OF  VITIATED  AIE  743 

immediate  reinspiration  of  a  portion  of  our  expired  breath.  This  occurs 
quite  commonly,  in  fact  may  almost  be  regarded  as  a  normal  accom- 
paniment of  respiration  during  the  major  part  of  our  lives.  Lehmann  ^ 
and  also  Heymann  ^  determined  the  COo  of  the  inspired  air,  compared 
this  with  the  CO2  of  the  surrounding  air,  and  from  the  difference  com- 
puted the  proportion  of  the  breath  which  was  reinspired.  They  found 
this  proportion  to  vary  greatly.  It  was  sometimes  more  than  6  per 
cent.,  but  dropped  to  zero  in  the  open  air,  and  in  a  breeze  of  3  meters 
per  second.  Crowder "  confirms  these  observations  and  extends  them 
much  further.  He  shows  that  under  many  conditions  the  air  about  the 
face  contains  much  more  CO2  than  the  surrounding  air.  The  path  of 
the  expired  air  may  roughly  be  seen  by  watching  the  course  of  smoke 
blow  from  the  nostrils.  The  expired  air  leaves  in  a  cone-shaped  expan- 
sion, part  of  which  lies  quite  close  to  the  body,  and  then  rises  slowly  by 
convection  currents.  Inspiration  follows  expiration  immediately,  there- 
fore every  chance  is  offered  for  some  of  the  expired  air  to  be  again 
drawn  in,  except  when  facing  a  breeze  of  from  200  to  300  feet  per 
minute,  or  when  walking,  riding,  or  fanning.  When  the  back  is  turned 
to  a  breeze  a  little  of  the  expired  air  is  often  reinhaled  in  spite  of  the 
current. 

The  position  of  the  head  influences  the  amount  of  air  rebreathed. 
Thus  Crowder  has  shown  that  while  sitting  upright  the  reinspiration 
was  2.3  per  cent. ;  lying  down  with  a  pillow  tilting  the  head  forward, 
1.3  per  cent;  lying  flat,  head  thrown  back,  none  at  all.  In  the  ordinary 
position  in  bed,  with  the  head  on  the  side  and  flexed,  with  pockets  or 
dead  spaces  for  the  air  to  stagnate,  there  will  be  a  greater  retention  of 
expired  air.  This  occurs  especially  when  the  head  sinks  into  a  soft 
pillow. 

It  may  be  concluded  that  when  one  lives  indoors  and  remains  quiet 
he  will  immediately  rebreathe  from  1  to  3  per  cent,  of  his  own  expired 
air;  in  bed  it  will  be  more,  from  1  to  5  per  cent.,  and  even  10  to  18 
per  cent.,  depending  on  the  position  in  which  he  lies.  Nor  does  sleep- 
ing in  the  open  insure  "pure"  air,  for  breathing,  especially  when  one 
buries  his  head  between  pillows  and  bedclothes  for  the  sake  of  warmth. 
On  the  other  hand  it  is  plain  that  "a  little  extension  of  the  dead  space 
beyond  the  tip  of  the  nose  is  of  no  consequence." 

*  Lehmann:  "Der  Kohlensauregehalt  der  Inspirationsluft  im  Freien  und  im 
Zimmer,"   Arch.  f.   Hyg.,    1899,   XXXIV,   315. 

^  Heymann :  "Ueber  den  Einfluss  wieder  eingeathmeter  Expirationsluft  auf 
die  Kohlensiiure-Abgabe,"  Ztschr.  f.  Hyg.,  1905,  XLIX,  388. 

'Crowder:   Archives  of  Internal  Med.,  Oct.,   1913,  Vol.   12,  pp.  420-451. 


744  FEESH  AND  VITIATED  AIR 


SUMMARY 


It  is  now  perfectly  plain  that  the  ill  effects  resulting  from  a  vitiated 
atmosphere  are  not  due  to  an  increase  of  carbon  dioxid  nor  to  a  dim- 
inution in  oxygen.  Upon  this  point  all  are  agreed.  The  general  con- 
sensus of  opinion  also  excludes  poisonous  bodies  in  the  expired  breath 
as  a  factor. 

Sanitarians  are  satisfied,  with  the  evidence  presented,  that  most  of 
the  discomfort  is  due  to  physical  changes  only.  If  a  normal  heat  inter- 
change can  be  maintained  between  the  body  and  the  air  the  symptoms 
which  are  commonly  attributed  to  poor  ventilation  do  not  develop.  Ac- 
cording to  this  view  the  vital  element  of  the  ventilation  problem  becomes 
that  of  regulating  the  temperature,  moisture,  and  motion  of  the  air. 
When  the  air  is  still  we  are  surrounded  by  an  "aerial  envelope"  with 
a  temperature  and  moisture  resembling  the  open  air  on  a  hot  and  humid 
day.  The  symptoms  caused  by  crowd  poisoning,  such  as  oppression, 
malaise,  headache,  vertigo,  nausea,  vomiting,  and  even  collapse,  indeed 
resemble  those  of  heat  exhaustion. 

Metabolism  is  reflexly  retarded  by  a  warm  aerial  envelope,  and  stimu- 
lated by  cool  moving  air,  the  consumption  of  oxygen  by  the  tissues  and 
the  production  of  CO2  by  them  being  much  less  in  warm  air  than  in 
cold  air. 

Even  those  who  look  upon  the  physical  changes  in  the  air  as  the 
sole  cause  of  the  discomfort  rather  than  the  possibility  of  chemical 
changes  admit  that  a  certain  amount  of  fresh  air  must  be  supplied. 
Fliigge  himself  urges  that  life  in  the  open  should  be  more  and  more 
resorted  to,  but  he  would  have  the  motive  correctly  understood,  not 
that  the  chemical  condition  of  inside  air  is  harmful,  but  that  it  is  the 
overheating  of  rooms  that  causes  disturbances  of  health.  Fliigge  states 
that  one  should  go  into  the  open  not  because  he  may  breathe  chemically 
purer  air,  but  because  its  almost  constant  motion  carries  away  the  body 
heat  and  causes  a  beneficial  stimulation  of  the  skin  and  reflexly  brings 
about  a  heightened  cell  activity  that  aids  in  the  development  of  sturdy 
health.  The  chemistry  of  air  and  "crowd  poisons"  have  little  or  no 
part  to  play  in  the  explanation  of  outdoor  benefits  or  of  indoor  discom- 
forts. These  are  both  dependent  upon  physical  conditions,  and  their 
explanation  rests  with  the  physics  of  heat  interchange  between  the  body 
and  its  surrounding  medium. 

There  is  some  danger  in  regarding  the  ill  effects  of  poor  ventilation 
as  due  to  thermal  and  other  physical  factors  alone.  According  to  this 
theory  it  is  only  necessary  to  keep  the  temperature  and  moisture  down 
and  keep  the  air  in  motion;  a  closed  ofifice  with  an  electric  fan  would 
take  the  place  of  any  system  of  ventilation.     There  is  already  a  clamor 


SUMMAEY  745 

against  the  laws  requiring  fresh  air  in  workrooms,  based  upon  Fliigge's 
views.  This  is  a  natural  corollary  of  Fliigge's  views.  If  re-breathing 
the  same  air  is  not  hurtful,  the  ventilation  of  living  rooms  may  be  greatly 
simplified  by  simply  keeping  the  physical  conditions  of  the  air  within 
the  limits  of  comfort.  Furthermore,  a  great  economy  would  be  effected. 
It  is,  however,  not  scientific  to  insist  that  the  chemical  changes  in  a 
vitiated  atmosphere  may  be  disregarded,  because  we  cannot  at  present 
demonstrate  immediate  relationship  between  cause  and  effect;  neither 
is  it  safe  to  deny  dogmatically  the  existence  of  injurious  substances  in  a 
vitiated  atmosphere  simply  because  in  the  present  state  of  our  knowledge 
chemistry  has  failed  to  demonstrate  them,  and  because  most  of  the  symp- 
toms may  be  explained  upon  disturbances  of  thermic  interchange.^ 

Furthermore,  most  of  the  observations  have  been  based  upon  short 
exposures;  it  is  very  probable  that  a  decrease  in  mental  and  physical 
efficiency  would  result  from  a  prolonged  exposure  to  a  vitiated  atmos- 
phere, even  though  it  were  kept  dry  and  cool.  The  improvement  in 
appetite,  nerve  vigor,  blood  quality,  and  muscular  tone  which  follows 
open  air  treatment,  even  in  the  rich  and  well-fed,  shows  the  paramount 
importance  of  fresh  air. 

^See  also  Sewall,  Interstate  Med.  Jour.,  XXIII,  Jan.  1,  1910. 


CHAPTER  VI 
VENTILATION  AND  HEATING 

VENTILATION 

The  problem  of  ventilation  is  apparently  a  very  simple  one;  all 
that  is  required  is  to  furnish  a  never-ending  stream  of  fresh  air  from 
the  inexhaustible  supply  without  to  replace  that  which  is  constantly 
being  vitiated.  To  do  this  under  the  artificial  conditions  of  house 
and  factory  life  is  often  extremely  difficult,  and  under  certain  circum- 
stances practically  impossible.  Further,  the  problem  of  ventilation 
must  take  into  account  not  only  the  quantity  of  air,  but  its  physical 
condition,  in  order  that  the  human  machine  may  operate  at  the  highest 
level  of  health  and  efficiency. 

Ventilation  must  serve  a  number  of  purposes  and  comply  with  a 
number  of  conditions  before  it  can  be  considered  satisfactory:  (1)  it 
must  bring  pure  air  from  without  in  order  to  dilute  and  remove  the 
products  of  respiration,  as  well  as  other  sources  of  vitiation;  (2)  it 
must  maintain  the  air  within  the  room  at  a  proper  temperature  and 
humidity,  and,  further,  must  keep  the  air  of  the  room  in  gentle  and 
continuous  motion;  (3)  it  must  remove  the  gases,  odors,  bacteria,  dust, 
and  other  substances  that  contaminate  the  air  of  inclosed  spaces;  (4) 
it  must  dilute  and  remove  the  impurities  produced  by  the  burning  of 
gas,  candles,  lamps,  and  other  sources. 

The  purpose  of  ventilation  is  not  to  bring  outdoor  conditions  in- 
doors; the  art  of  ventilation  consists  in  adapting  indoor  conditions  to 
indoor  life.  Indoor  life  is  necessary  in  order  to  perform  the  delicate 
manipulations  which  cannot,  as  a  rule,  be  effectively  conducted  outdoors. 
Indoor  life,  then,  involves  quiet  and  protection  from  sudden  changes 
or  extremes. 

It  is  a  simple  mechanical  problem  to  condition  the  air  of  an  apart- 
ment. The  ventilating  engineer  finds  no  difficulty  in  regulating  the 
temperature  and  humidity  within  narrow  limits,  and  in  furnishing 
definite  quantities  of  fresh,  moving  air.  To  maintain  these  conditions, 
however,  the  doors  and  windows  must  be  kept  shut.  Herein  arises  the 
first  difficulty  between  the  theory  and  the  practice  of  ventilation,  for 
it  is  plain  that  the  simplest  and  often  the  best  way  to  ventilate  a  room 

746 


VENTILATION"  747 

is  through  open  windows.  The  second  difficulty  arises  from  the  fact 
that  the  conditions  within  and  without  the  room  to  be  ventilated  are 
not  constant.  The  principal  factors  here  concerned  are  the  force  and 
direction  of  the  wind,  changes  of  outdoor  temperature,  and,  to  a  less 
degree,  movements  within  the  room.  It  is,  therefore,  much  easier  to 
maintain  constant  air  conditions  in  a  sub-basement  than  in  a  room 
exposed  to  wind  and  weather.  Air  conditioning  is  now  an  established 
engineering  science,  and  the  engineer  is  prepared  to  supply  any  kind 
of  air  that  is  desired. 

The  efficiency  of  any  system  of  ventilation  must  be  measured  by 
the  results  obtained  at  the  breathing  zone.  It  matters  little  what  the 
composition  or  the  condition  of  the  air  is  near  the  ceiling,  provided  the 
heated,  moistened,  and  vitiated  aerial  blanket  which  surrounds  us  is 
constantly  removed  and  replaced  with  a  fresh  supply  properly  condi- 
tioned. 

Ventilation  is  far  from  satisfactory  if  the  air  brought  into  the  room 
is  smoky,  dusty,  or  bacteria-laden,  or  if  it  is  contaminated  with  gases 
or  odors  from  cellars  or  surroundings.  Attention  should,  therefore,  be 
given  to  the  sources  of  the  air,  and  it  is  always  an  advantage  to  wash  or 
filter  it.  There  is  a  practical  limit  to  the  amount  of  fresh  air  that  may 
profitably  be  forced  into  a  room,  especially  warmed  air  in  the  winter 
time.     Ventilation  and  heating  naturally  go  hand  in  hand. 

The  belief  is  growing  that  it  is  not  dangerous  to  rebreathe  air,  and 
the  view  is  spreading  that  the  hygienic  value  of  ventilation  for  the  pur- 
pose of  maintaining  a  chemically  pure  atmosphere  in  dwellings,  schools, 
and  hospitals  is  not  so  great  as  is  commonly  supposed.  According  to 
this  view  it  is  more  important  to  ventilate  in  the  interest  of  the  heat 
economy  of  the  body,  by  the  establishment  of  a  suitable  temperature  and 
air  movement,  and  by  the  regulation  of  the  humidity  in  the  atmosphere. 
The  established  facts,  that  the  principal  causes  of  the  ill  effects  of  viti- 
ated air  are  due  more  to  the  heat  and  humidity  and  stillness  of  the  air 
than  to  changes  in  its  chemical  composition,  have  led  some  hygienists  to 
recommend  rebreathing  the  air,  provided  the  physical  conditions  are 
kept  favorable. 

Satisfactory  ventilation  should  not  only  take  into  account  the  physi- 
cal conditions  of  the  air,  but  also  demands  a  generous  supply  of  fresh 
air  in  order  to  keep  the  chemical  composition  within  reasonably  normal 
limits.  Clean  air  in  motion  and  of  proper  temperature  and  humidity 
is  necessary  to  indoor  comfort. 

The  rigor  of  a  cold  climate  makes  of  its  inhabitants  a  house-dwelling 
race.  Under  these  conditions  houses  are  commonly  overheated,  if  not 
by  fire  and  steam,  then  by  the  heat  of  the  inhabitants'  bodies.  When 
people  do  this  they  complain  of  poor  ventilation,  regardless  of  whether 
the  air  supply  is  large  or  small. 


748  VENTILATION"  AND  HEATING 

Dwelling  houses  are  usually  constructed  with  little  regard  for  ven- 
tilation. It  is  desirable  that  adequate  provision  should  be  made  for 
the  ventilation  of  every  house  that  is  built.  This  requires  just  as  much 
care  and  forethought  as  the  system  of  heating  the  house,  or  furnishing 
it  with  water,  gas,  electricity,  plumbing  for  the  disposal  of  wastes,  and 
other  household  conveniences.  Whatever  system  of  ventilation  may  be 
adopted,  it  is  wise  to  flush  rooms  frequently  with  fresh  air  and  flood 
them  with  sunshine.  This  helps  to  blow  out  the  accumulated  dust  and 
bacteria,  to  oxidize  organic  matter  that  collects  as  a  film  on  all  surfaces, 
to  diminish  odors,  and  generally  to  purify  the  apartment. 

Air  Washing. — The  process  of  air  washing  consists  of  passing  the  air 
horizontally  through  a  chamber  in  which  water  is  falling  in  drops  as 
rain,  or  into  which  it  is  sprayed.  The  sprays  are  obtained  by  forcing  the 
water  out  of  perforated  pipes  or  through  nozzles  placed  across  ducts. 
When  the  sprays  intersect  they  are  said  to  form  a  curtain.  The  object 
is  to  bring  the  air  and  water  into  intimate  contact.  Besides  the  washing 
chamber  there  are  heating  or  tempering  coils  in  the  ducts,  or  in  a  sep- 
arate chamber,  and  devices  for  controlling  the  temperature.  The  water 
used  for  washing  is  circulated  by  means  of  a  pump  so  that  it  may  be 
used  over  and  over  in  the  spray  chamber  for  a  considerable  time. 

Washing  takes  out  many  of  the  impurities  in  the  air,  as  bacteria, 
molds,  dust,  epithelial  scales,  particles  of  various  descriptions,  also  odors 
and  some  gases,  but  not  CO2.  Washing  is  the  best  way  to  purify  the  air 
as  it  imitates  nature's  process  through  a  rain  shower.  If  desired,  the 
water  may  be  cooled  in  the  summer  time  so  as  to  influence  the  tempera- 
ture of  the  air.  Several  forms  of  air  washers  are  on  the  market,  essen- 
tially similar  in  principles,  but  differing  in  details  of  construction. 

Recirculation. — The  cost  of  heating  large  volumes  of  cold  air  has 
naturally  stood  in  the  way  of  efficient  ventilation  of  schools  and  factories 
during  the  cold  weather.  Another  question  has  been  the  low  indoor 
relative  humidity  produced  by  heating  outdoor  air  to  a  comfortable 
room  temperature.  Washing  and  recirculating  the  air  overcomes  both 
of  these  objections  because  it  furnishes  an  ample  supply  of  conditioned 
air  in  motion.  The  method  has  attracted  favorable  attention.  Naturally 
there  must  be  a  limit  to  the  continued  use  of  the  same  air,  but  ordinary 
leakage  and  the  use  of  a  certain  percentage  of  outside  air  prevent  the 
concentration  of  any  substances  not  removed  by  the  washer. 

The  advantage  of  washing  and  recirculating  the  air  lies  in  the  great 
saving  of  fuel  in  cold  weather.  At  the  gymnasium  of  the  International 
Y.  M.  C.  A.  College  at  ;Springfield,  it  was  estimated  that  a  saving  of 
from  40  to  50  per  cent  of  coal  resulted  from  recirculatiiig  the  air. 

Eecirculated  air,  when  washed,  may  be  better  than  outside  air  un- 
washed, being  freer  from  dust  and  bacteria,  and  not  appreciably  less 
in  oxygen  or  higher  in  COg;  however,  it  is  not  equal  to  outside  air 


VENTILATION  749 

washed.  Recirculation  may  be  subject  to  abuse,  and  if  used  must  be 
carefully  watched. 

Vitiation  by  Eespiration. — An  adult  individual  at  rest  breathes  at 
the  rate  of  about  seventeen  respirations  a  minute.  At  each  respiration 
about  500  c.  c.  (30.5  cu.  in.)  of  air  pass  in  and  out  of  his  lungs.  The 
air  in  the  lungs  loses  about  4  per  cent,  of  oxygen  and  gains  3.5  to  4 
per  cent.  COg.  The  nitrogen  remains  unchanged.  In  addition  the 
expired  air  is  raised  in  temperature  to  nearly  that  of  the  blood,  98.4°  F. ; 
it  also  contains  much  aqueous  vapor. 

The  amount  of  CO2  which  is  given  off  by  an  adult  male  person  at 
rest  can  be  calculated  from  the  above  figures,  and  will  be  found  to  be 
0,68  cubic  foot  in  one  hour.     Thus : — 

17  X  30  X  60 

=   17 . 2  cubic  feet  breathed  per  hour. 

1728 
4  per  cent,  of  17 . 2  =  0 .  68  cubic  foot  per  hour  of  CO2. 

From  actual  experiment  it  has  been  determined  that  an  average 
adult  gives  off  0.9  of  a  cubic  foot  of  CO2  during  gentle  exertion,  and 
possibly  as  much  as  1.8  during  hard  work.  The  adult  female  gives  off 
about  one-fifth  less  under  similar  circumstances,  and  an  infant  is  said 
to  give  off  about  0.5  cubic  foot  of  CO2  per  hour.  In  a  mixed  assembly 
at  rest,  including  male  and  female  adults  and  children,  the  CO2  given  off 
per  head  is,  therefore,  taken  as  0.6  of  a  cubic  foot. 

The  volume  of  air  inspired  and  expired  depends  on  the  rate  and 
extent  of  the  respiratory  movement,  but  in  an  adult  man  of  average  size 
and  vigor  about  500  cubic  centimeters  of  air  are  inspired  and  expired 
during  quiet  breathing.  This  volume  of  air  is  known  as  the  tidal  air, 
and,  since  the  total  volume  of  air  in  the  lungs  is  about  3,500  c.  c,  it 
is  evident  that  in  normal  breathing  a  large  amount  of  air — 3,000  c.  c. — 
remains  in  the  lungs  at  the  end  of  expiration.  The  air  which  remains 
behind  is  known  as  stationary  air. 

By  forced  expiration  about  half  of  the  stationary  air,  i.  e.,  1,500 
c.  c,  can  be  expired,  and  this  portion  of  the  stationary  air  is  known 
as  the  supplemerital  or  reserve  air,  while  the  final  1,500  c.  c,  which  no 
effort  can  expel,  is. known  as  the  residual  air.  The  total  of  3,500  c.  c. 
of  air  in  the  chest,  then,  at  the  end  of  ordinary  inspiration  is  made 
up  as  follows : 

Tidal  air 500  c.  c. 

Stationary  air  f  Supplemental  or  reserve. . . .'. 1,500  c.  c. 

\  Residual  air 1,500  c.  c, 

3,500  c.  c. 

When,  however,  inspiration  is  forced,  another  1,500  c.  c.  of  air,  known 
as  complemental  air,  can  be  inspired,  making  altogether  5,000  c.  c. 


750  VENTILATION  AND  HEATING 

The  total  amount  of  air  (complemental,  tidal,  supplemental)  which 
can  be  inspired  after  forced  expiration  is  known  as  the  "respiratory 
capacity"  or  "vital  capacity"  or  "extreme  differential  capacity,"  and  the 
amount  varies  considerably  according  to  height,  weight,  vigor,  age,  etc. 

Dead-Space  Air. — With  each  breath,  we  take  back  into  the  lungs  the 
air  contained  in  the  nose  and  larger  bronchi — the  "dead-space"  air.  This 
dead-space  air  constitutes  about  one-third  of  the  whole  volume  of  quiet 
inspiration,  and  not  less  than  one-tenth  of  deep  breathing.  To  all 
intents  and  purposes  it  is  expired  air  which  is  constantly  reinspired. 
Ee-breathing  of  the  ordinary  dead-space  air  is  a  normal  and  conserva- 
tive process ;  it  prevents  pure  cold  air  from  entering  the  lungs  and  reduc- 
ing the  CO2  below  the  amount  required  for  stimulating  the  respiratory 
center;  it  makes  of  breathing  a  regular  and  continuous  rather  than 
an  irregular  and  interrupted  function.  Douglas  and  Haldane  have  re- 
cently shown  that  the  volume  of  the  dead-space,  instead  of  being  a  fixed 
quantity,  is  automatically  altered  so  as  to  give  greater  or  less  resistance 
to  the  air-flow  to  and  from  the  lungs  with  changing  exertion.  They  go 
so  far  as  to  state  that  rather  marked  variations  may  occur;  and,  while 
the  mechanism  is  not  fully  understood,  they  think  the  regulation  is  as 
perfect  as  is  that  of  the  size  of  the  arterioles  for  controlling  the  blood 
flow. 

Factor  of  Safety. — Bernard  and  Mantoux  ^  have  shown  that  the  lungs 
are  capable  of  performing  the  respiratory  function  even  when  the  capac- 
ity is  reduced  to  one-sixth  of  the  normal.  Furthermore,  we  should 
remember  that  the  possibility  of  increase  in  the  depth  of  inspiration  is 
400  to  500  per  cent.,  and  that  by  changing  the  rate  and  the  complete- 
ness of  expiration  the  alveolar  ventilation  may  be  increased  considerably 
more  than  1,000  per  cent.  From  this  great  margin  of  safety  it  is  easy 
to  understand  why  a  slight  increase  of  CO2  in  the  inspired  air  falls  far 
below  the  limits  of  our  conscious  effort.  From  the  experiments  of  Hal- 
dane and  Priestley  ^  an  actual  increase  of  100  per  cent,  in  the  pulmonary 
ventilation  passes  almost  unnoticed.  The  factor  of  safety  which  Melzer  ^ 
has  so  well  described  as  belonging  to  all  well  understood  physiologic 
processes,  is  here  a  very  generous  one. 

The  Amount  of  Air  Required.— Omitting  from  consideration  the  ques- 
tion of  temperature  and  moisture,  a  certain  amount  of  pure  air  is 
necessary  for  good  ventilation.  This  amount  is  determined  from  the 
amount  of  carbon  dioxid  taken  as  an  index  of  the  impurities  from 
respiration  and  combustion,  and  may  be  ascertained  either  by  direct  ob- 

^  Bernard  and  Mantoux:  "Capacite  pulmonare  minima  compatible  avec  la 
vie,"  Jour,  de  Physiol.  Exper.,  1913,  XV,  16  (Ed.  Abstr.  in  Jour.  Am.  Med. 
Assn.,  1913,  LX,   1794). 

'^  Haldane  and  Priestley :  "The  Regulation  of  the  Lung  Ventilation,"  Jour. 
Physiol,  1905,  XXXII,  225. 

^  Melzer :  "Factors  of  Safety  in  Animal  Structure  and  Animal  Economy," 
Harvey  Lectures,  New  York,   1907-8,  p.   139. 


VENTILATION  751 

servation  or  from  physiological  data.  The  accepted  amount  of  pure  air 
required  per  person  per  hour  is  from  2,000  to  3,000  cubic  feet.  The 
external  air  contains  3  parts  of  COj  per  10,000  (0.03  per  cent.),  and 
the  permissible  limit  for  indoor  air  is  placed  at  from  6  to  10  parts.  The 
volume  of  air  in  itself  is  not  as  important  a  factor  in  ventilation  as 
the  necessity  for  the  maintenance  of  air  movement  to  facilitate  the  elim- 
ination of  heat  and  moisture.  It  is  interesting  to  note  that  it  requires 
just  about  as  much  air  to  regulate  heat  interchange  as  to  dilute  the 
CO2  to  permissible  limits.  The  amount  of  air  needed  in  good  ventila- 
tion, therefore,  remains  about  the  same  as  formerly,  but  our  reasons  for 
supplying  it  have  changed. 

It  has  been  found  from  actual  observation  that  an  adult  in  an  air- 
tight compartment  will  vitiate  the  air  as  follows : 

In  a  room  3,000  cubic  feet  CO2  =  0 .  06  per  cent,  in  1  hour 
«    "     "      2,000      "        "       "     =0.07    "       "       "  "     " 
«    «     "      1,500      "        "       "     =0.08    "       "       "  "     " 
«   «     «      J  200      "        "       "    =0.09    "       "       "  "     " 

«      «        u  J^  QQQ  «  «  «        _    Q    ^Q      ti  «  «    «         « 

The  same  results  may  be  obtained  from  physiological  data.  Thus, 
the  average  adult  expires  0.6  cubic  foot  of  CO2  per  hour.  The  differ- 
ence between  the  permissible  limit,  0.06  per  cent.,  and  the  amount  of 
carbon  dioxid  in  the  air,  0.03  per  cent.,  is  0.03.  It  follows  that  the 
amount  of  fresh  air  required  per  hour  by  an  adult  to  keep  the  COo  down 
to  0.06  per  cent,  may  be  determined  from  the  following  equation : 

0.03  :0.6  ::100  :x 
X  =  2,000  cubic  feet 

If  the  normal  amount  of  carbon  dioxid  in  the  air  is  taken  as  0.04 
instead  of  0.03,  the  result  is  3,000  cubic  feet,  the  amount  generally 
accepted,  which,  however,  is  somewhat  in  excess — as  it  should  be.  This 
does  not  mean  that  there  should  be  3,000  cubic  feet  for  each  person 
in  an  inhabited  room,  for  it  is  sufficient  if  the  air-space  is  1,000  cubic 
feet,  provided,  of  course,  the  air  is  changed  three  times  an  hour. 

The  same  results  may  he  obtained  by  using  the  formula: 

E 

—  =  D 
P 

B=the  amount  of  carbon  dioxid  exhaled  by  one  person  in  one 
hour;  the  general  average  for  an  adult  being  0.6  cubic  foot. 

P=the  amount  of  added  CO,  permitted,  stated  in  cubic  feet;  or 
0.06—0.03=0.03  per  cent,  or  0.000,3  cubic  foot. 

D^the  required  delivery  of  fresh  air  in  cubic  feet  per  hour. 


762  VENTILATION  AND  HEATING 

E  0.6 

—  =  D,  or =  2,000  cubic  feet. 

P  0.0003 

The  primary  value  of  E  in  this  equation  varies  with  different  con- 
ditions. 

A  male  adult  (160  pounds)  exhales  0.72  cubic  foot  of  CO2  per  hour 
A  female  adult  (120  pounds)  exhales  0.60  cubic  foot  of  CO2  per  hour 
A  child  (  80  pounds)  exhales  0 .  40  cubic  foot  of  CO2  per  hour 

Average  0 .  60 

These  values  vary  also  with  rest  or  work.  Thus,  factories  or  work- 
shops where  men  are  actively  employed  need  more  air  proportionately. 
In  light  work  a  man  weighing  160  pounds  exhales  0.95  cubic  foot,  while 
at  hard  work  1.84  cubic  feet,  of  CO2  per  hour. 

A 

The  formula  suggested  by  DeChaumont  is  D  = 

B-C 

A:=quantity  of  CO,  given  off  per  hour  per  person=:0.6  cu.  ft. 

B=:proposed  permissible  maximum  quantity  of  CO2  per  1,000  cu. 
ft.=0.6  per   1,000. 

C=amount  of  CO,  present  in  1,000  cu.  ft.  of  fresh  air  (0.3  cu.  ft. 
per  1,000  cu.  ft.). 

D=:amount  of  fresh  air  required  per  head  each  hour  to  maintain 
the  standard  B  expressed  in  thousands  of  cu.  ft. 

A  0.6  0.6 

Then  D  = or =  —  =  2,000  cu.  ft. 

B^C       0.6-0.3       0.3 

of  air  needed  per  head  per  hour. 

In  case  of  individuals  doing  light  work  and  giving  off  0.95  cu.  ft. 
CO2  per  hour,  then 

0.95 

D  = =  3,166  cu.  ft. 

0.6-0.3 

This  is  a  convenient  formula,  for  it  may  be  used  not  only  to  deter- 
mine the  amount  of  fresh  air  required,  but,  knowing  the  other  factors, 
the  amount  of  cubic  feet  of  fresh  air  that  has  been  admitted  to  a  room 
per  head  may  be  determined.  Further,  probable  conditions  of  the  at- 
mosphere of  a  room  into  which  a  known  amount  of  fresh  air  has  been 
supplied  can  be  determined  by  finding  the  value  of  B,  thus ; 

A 
B  =  — +  C 


VENTILATION  753 

Standards  of  Purity — Efficiency  of  "Ventilation. — There  is  no  single 
standard  by  which  the  purity  of  the  air  or  the  efficiency  of  ventilation 
can  be  determined.  We  must  know  at  least  five  factors :  ( 1 )  the  tem- 
perature; (2)  the  humidity;  (3)  the  movements  of  the  air;  (4)  the 
amount  of  CO2  it  contains;  (5)  dust,  bacteria,  gases,  etc.  In  a  general 
way  it  may  be  stated  that  the  best  results  are  obtained  when  the  tem- 
perature is  between  62°  and  68°  F.;  the  moisture  not  above  50  per  cent, 
relative  humidity  (the  wet  bulb  under  70°  F.) ;  the  movement  gentle, 
without  draft;  COg  not  in  excess  of  6  parts  per  10,000;  and,  finally, 
freedom  from  excessive  dust,  bacteria,  gases,  etc.  Even  where  all  these 
factors  are  found  satisfactory  there  is  still  one  test  that  must  be  made 
in  order  to  be  sure  that  our  ventilating  system  is  nowhere  at  fault — that 
is,  the  clinical  test.  Persons  occupying  the  room  should  suffer  from 
none  of  the  well-known  effects  produced  by  air  in  poor  condition.  The 
room  should  be  free  from  unpleasant  odors.  If  our  tests  seem  right,  but 
the  air  seems  close,  something  must  be  wrong  with  the  tests.  The  evi- 
dence of  our  senses  and  clinical  experience  cannot  be  disregarded. 

Where  any  ventilating  device  is  installed  it  is  readily  possible  to 
measure,  by  means  of  the  anemometer,  the  amount  of  air  passing  through 
inlets  or  outlets,  but  it  is  often  difficult  to  trace  the  course  of  the  air  in 
the  room.  The  measured  volume  of  air  passing  through  inlets  and  out- 
lets does  not  necessarily  determine  the  efficiency  of  ventilation  in  main- 
taining a  continuous  renewal  of  the  air  at  the  breathing  zone. 

The  volume  of  fresh  air  entering  the  breathing  zone  may  be  esti- 
mated with  considerable  accuracy  by  determining  the  proportion  of 
CO2  which  this  zone  contains.  The  air  supplied  is  inversely  as  the 
respiratory  contamination.  It  may  be  computed  from  the  following 
equation : 

vp 

A= 

x-N 

v=the  CO2  produced  by  one  person;  that  is,  0.6  cubic  foot  per  hour. 

pz=the  number  of  people  in  the  room. 

x=:the  proportion  of  CO,  per  cu.  ft.  in  the  inside  air. 

]Sr=the  proportion  of  CO2  per  cu.  ft.  in  the  outside  air  (0.0003). 

A=the  air  supplied  to  the  room  in  cubic  feet  per  hour. 


0.6  p 
A= 


X- 0.0003 


It  will  be  seen  in  this  equation  that  vp  represents  the  CO2  produced 
by  occupants  and  x— N  represents  the  respiratory  contamination. 


754  VENTILATION  AND  HEATING 

In  such  computations,  as  also  in  the  direct  measurement  of  air  sup- 
plies, it  is  the  averages  which  are  most  important.  From  average  con- 
tamination we  may  find  average  air  supplies.  Erroneous  conclusions 
are  very  likely  to  be  drawn  from  single  determinations. 

Another  method  of  determining  the  efficiency  of  ventilation  is  in- 
tentionally to  vitiate  the  air  of  a  room,  and  then,  after  a  lapse  of  a 
certain  time,  find  how  far  ventilation  has  removed  the  carbon  dioxid. 
The  amount  of  air  which  has  entered  the  room  may  be  found  by  the 
formula ; 

Pi-a 

C  =2.303  m  log 

P2-a 

C^amount  of  air  which  has  entered;  2.303  is  a  constant. 

m=:capacity  of  the  room. 

Pi=amount  of  carbon  dioxid  originally  present  (found  by  experi- 
ment). 

Pg^^amount  of  carbon  dioxid  present  after  vitiation. 

a=amount  of  carbon  dioxid  in  the  outside  air. 

The  Size  and  Shape  of  the  Room. — These  are  exceedingly  important 
factors  in  any  system  of  ventilation.  It  at  once  becomes  evident  that 
a  man  in  a  diving  suit  with  a  good  circulation  of  fresh  air  is  better 
off  than  occupants  of  a  spacious  but  poorly  ventilated  apartment  in 
which  the  air  has  become  vitiated  through  long  occupancy.  The  air  in 
a  small  cabin  on  a  steamship  may  be  infinitely  better  than  the  air  in 
a  large  room  of  a  country  home.  A  rathskeller  in  the  sub-basement  may, 
with  a  modern  system  of  ventilation,  have  much  better  air  than  that 
found  in  a  department  store  with  acres  of  floor  space  and  high  ceilings. 
In  other  words,  a  small  space  is  sufficient  if  properly  ventilated ;  a  large 
space  inadequate  if  improperly  ventilated. 

The  size  of  rooms  for  dwellings  and  workshops  is  somewhat  of  an 
economic  question,  but  they  should  be  large  enough  to  allow  the  air 
to  be  replaced  two  or  three  times  an  hour  without  causing  perceptible 
drafts.  The  minimal  space,  in  accordance  with  this  standard,  is  about 
one-third  the  quantity  of  air  required  per  hour;  that  is,  from  700  to 
1,000  cu.  ft.  per  person.  The  amount  of  space  naturally  varies  with 
dwellings,  factories,  schools,  theaters,  prisons,  hospitals;  also  with  the 
length  of  time  the  room  is  occupied  and  the  nature  of  the  work  there 
carried  on.  Thus,  in  hospitals  where  ordinary  cases  are  cared  for,  from 
1,800  to  2,000  cu.  ft.  of  air  is  desirable  for  each  patient,  while  no  less 
than  2,500  cu.  ft.  should  be  allowed  for  each  fever  patient.  Soldiers 
in  barracks  are  allowed  600  cu.  ft.  per  head,  and  the  limit  for  lodging 
houses  is  usually  fixed  at  from  300  to  500  cu.  ft.  The  U.  S.  Emigration 
Law  requires  500  cu.  ft.  per  head  in  the  steerage.     In  figuring  the 


VENTILATION 


755 


amount  of  air  space  in  a  room  allowance  should  be  made  for  furniture, 
projecting  surfaces,  and  other  objects  which  diminish  the  available  space. 
The  following  table  from  Parkes  and  Kenwood  shows  the  attempts 
made  by  Great  Britain  to  fix  the  minimum  space  allowed  per  head  by 
legislation : 


Minimum  Space 
per  Head 
in  Cu.  Ft. 

Authority 

Common   lodging   houses    (sleeping 
rooms) 

300 
400 

300 
250 

400 
500 

400 

between  9  p.  m. 

and  6  a.  m. 

600 

1,200 

80 

130 

60 

40 

72 
800 

Local    Government    Board 

Registered  lodging  houses — 

Rooms  occupied  by  day  and  night. 
Rooms  occupied  by  night  only.  .  .  . 

Non-textile  workrooms  

(Model  By-laws). 

Ditto. 
Ditto. 
Factory  Act,  1901. 

Non-textile  workrooms  during  over- 
time  

Ditto. 

Underground  bakehouses 

Order  imder  Factory  Act, 

Above  -  ground    bakehouses    where 
night  work  is  carried  on  by  arti- 
ficial   light    other    than    electric 
light 

1901 

Army  barracks 

Ditto. 

British  Army  Regulations. 

Army  hospital  wards 

Ditto. 

Public  elementary  schools 

Educational  Department. 

London  County  Council  Schools. .  .  . 
Canal  boats  (persons  over  12  years) . 

Seamen's  cabins 

London  County  Council. 

Local  Government  Board, 
Regulations  under  the 
Canal    Boat    Act,    1877. 

Merchant  Shipping  Act. 

Cows  in  cowsheds 

Local  Government  Board, 

Model  Regulations  under 
the    Dairies,    Cowsheds, 
and    Milk-shops    Order. 

A  little  consideration,  however,  will  show  that  such  regulation  of 
space  is  by  itself  of  little  value.  Unless  there  be  movement  of  air, 
space  alone  is  futile.  However  large  the  space  may  be,  the  air  will  be- 
come impure  unless  fresh  air  circulates  through  it,  and  however  small 
the  space  the  air  may  be  kept  pure  by  sufficient  circulation. 

As  the  result  of  many  analyses  that  have  been  made  by  Haldane 
and  Osborne,  they  found  that  the  carbon  dioxid  bears  no  relation  to 
the  amount  of  air  space  under  practical  conditions.  In  fact,  the  most 
highly  vitiated  air  found  was  in  a  room  with  an  air  space  of  about 
10,000  cu.  ft.  per  person. 

It  is  not  alone  the  air  space  but  the  shape  of  the  room  that  influences 
ventilation.  It  is  a  mistake  to  suppose  that  a  lofty  room  is,  therefore, 
an  airy  room,  for  a  stratum  of  warm  vitiated  air  soon  occupies  the  upper 
portion  of  such  a  space,  and,  so  far  as  good  air  is  concerned,  has  the 


756  VENTILATION  AND  HEATING 

effect  of  lowering  the  effective  height  of  the  ceiling  to  the  top  of  the  door 
or  nearest  outlet.  Anyone  may  convince  himself  of  this  fact  by  getting 
up  on  a  stepladder  in  a  room  with  a  high  ceiling,  improperly  ventilated, 
and  occupied  for  some  hours.  The  upper  stratum  of  air  in  such  rooms 
is  frequently  stifling.  Ordinarily  12  feet  is  high  enough  for  the 
ceiling  of  school  rooms,  museums,  hospitals,  etc.,  and  9  feet  for  the  rooms 
of  private  dwelling  houses.  Where  there  is  little  or  no  movement  of 
the  air  it  soon  becomes  offensive,  no  matter  what  the  height  of  the 
ceiling. 

Floor  space  is  more  important  than  height.  The  necessity  for  an 
abundant  floor  space  is  shown  by  the  fact  that  a  small  inclosure  with 
four  high  walls  and  without  a  roof,  if  crowded,  speedily  becomes  oppres- 
sive. In  fact,  the  four  walls  are  not  necessary  to  demonstrate  this,  for 
"crowd  poisoning"  in  the  open  air  upon  a  still,  warm  day  is  a  common 
experience.  According  to  Harrington,  when  the  allowance  is  only  500 
cubic  feet  per  inhabitant,  the  floor  space  should  be  42  square  feet  (8I/2X 
5^),  In  the  English  barracks  the  soldiers  are  allowed  50  square  feet 
of  floor  space.  For  school  rooms  the  British  Educational  Code  requires 
120  cubic  feet  per  child  in  average  attendance  and  a  floor  space  of  10 
square  feet. 

Inlets  and  Outlets. — Whether  a  room  is  to  be  ventilated  by  natural  or 
mechanical  means,  proper  inlets  for  the  fresh  air  and  outlets  for  the 
vitiated  air  must  be  provided.  No  general  statement  as  to  the  best 
size  and  position  of  these  openings  will  apply  under  all  circumstances. 

Knowing  the  velocity  of  the  incoming  air,  the  area  of  the  inlets 
may  be  proportioned  so  as  to  permit  the  movement  of  the  necessary 
amount  of  air.  The  size  of  the  openings  under  specified  conditions  is, 
therefore,  a  matter  of  simple  arithmetic.  In  measuring  the  effective  area 
of  inlet  and  outlet  tubes  allowance  must  be  made  for  friction  and  for 
the  guards  or  fretwork  which  protect  the  openings.  These  often  di- 
minish the  effective  area  about  one-half. 

It  is  usually  better  to  admit  the  incoming  air  into  a  large  apart- 
ment through  a  number  of  openings  rather  than  through  one  large  one; 
the  same  holds  true  of  outlets.  Outlets  should  be  about  the  same  size 
as  inlets  and  should  be  placed  with  reference  to  them. 

All  air  ducts  tend  to  become  soiled  with  dust  and  soot  and  should, 
therefore,  be  guarded  with  wire  gratings,  muslin,  porous  flannel,  or 
other  protecting  and  filtering  devices,  and  they  should  also  be  cleaned 
periodically;  further,  it  should  be  borne  in  mind  that  ventilating  ducts 
are  favorable  highways  for  mice,  roaches,  and  vermin.  Inlets  opening 
upon  the  floor  are  objectionable,  as  they  collect  unusual  amounts  of 
dirt  and  dust,  which  are  then  blown  into  the  room. 

Whether  the  air  is  to  be  admitted  near  the  floor  and  taken  out  near 
the  ceiling  or  vice  versa  is  a  question  much  discussed  among  ventilating 


VENTILATIOIST 


75? 


engineers.  Various  possibilities  are  shown  in  the  diagram,  Fig.  92. 
The  natural  course  of  the  warmed  vitiated  air  is  upward,  and  it  would 
seem  that  the  upward  system  has  advantages  over  the  downward  system. 
However,  a  little  study  will  soon  convince  one  that  if  the  incoming  air 
is  warm  it  will  rise  at  once,  and  the  maximum  efficiency  will  be  lost 
at  the  breathing  line,  which,  after  all,  is  the  essential  stratum  of  air 
in  the  room.  Perhaps  the  best  arrangement  is  to  have  the  inlet  above 
and  the  outlet  below — both  upon  the  same  side  of  an  inner  wall. 


^%. 


>v\ 


<>^^ 


y^^. 


Fig.  92, — The  Position  of  Inlets  and  Outlets,  and  their  Relation  to  the  Aib 

Currents  in  a  Room. 


Outlet  ventilation  may  be  arranged  by  placing  a  bell  cover  ot  glass 
globe  over  the  gas  lights  and  conveying  the  heated  air  thence  to  the 
outer  air  by  means  of  ascending  tubes.  This  not  only  removes  the 
products  of  combustion,  but,  if  the  outlet  tubes  have  a  sufficient  area,, 
affords  a  very  good  system  of  ventilation.  An  automatic  system  of 
taking  the  air  out  of  a  room  may  also  be  provided  by  placing  a  shaft 
either  aroimd  the  chimney  flue  or  against  one  side  of  it.  The  column 
of  heated  air  in  the  ventilating  duct  will  rise  and  draw  the  vitiated 
air  out  of  the  room  with  which  it  is  connected.  The  same  may  be 
accomplished  by  placing  a  steam  jet  or  a  gas  burner  within  the  ventilat- 
ing duct  to  create  a  draft. 

Ventilating  ducts  usually  extend  up  the  walls  of  the  building  through 


758  VENTILATION  AND  HEATING 

the  roof,  and  should  be  in  as  direct  a  line  as  practicable.  The  openings 
upon  the  roof  may  be  protected  by  an  umbrella-like  covering  against 
rain,  or  they  may  be  cowled  to  prevent  down  drafts.  It  appears  that 
none  of  the  exhaust  cowls  cause  a  more  rapid  current  of  air  than  prevails 
in  an  open  pipe  under  similar  circumstances. 

Too  little  attention  has  been  paid  in  the  past  to  the  cleanliness  of 
the  air  supplied  to  our  buildings.  Fresh  air  inlets  are  often  located 
with  the  grossest  disregard  for  the  quality  of  the  incoming  air.  It  is 
not  uncommon  to  see  them  placed  on  the  sidewalk  level;  or  facing  a 
vacant  piece  of  ground  that  is  swept  by  clouds  of  dust;  or  where  smoke, 
the  spent  gases  from  automobiles,  or  objectionable  odors  may  be  taken  in. 

CroM^ded  buildings  and  dusty  city  streets  will  often  render  it  im- 
possible to  secure  clean  air  from  the  outside  atmosphere  without  re- 
sorting to  artificial  purification. 

External  Ventilation. — Model  city  planning  should  provide  streets 
of  sufficient  width,  and  should  regulate  the  height  of  buildings  and  also 
limit  the  extent  upon  which  the  land  may  be  biiilt,  so  as  to  allow  a  free 
circulation  of  air  about  all  structures  and  admit  a  flood  of  sunshine  for 
at  least  a  few  hours  during  the  day.  Some  of  our  metropolitan  streets 
resemble  canyons  rather  than  city  thoroughfares.  Crowded  tenements, 
facing  upon  narrow  streets  with  shafts  for  courts  and  backing  almost 
directly  upon  the  houses  in  the  rear,  and  further  surrounded  by  tall 
buildings  which  prevent  the  free  movements  of  the  outer  air,  and  shut 
out  the  sunshine,  should  be  prohibited,  whether  used  as  dwellings  or 
workshops.  In  such  places  the  ground  stays  moist,  the  air  becomes 
stagnant,  natural  ventilation  is  greatly  retarded,  and  the  conditions  upon 
a  hot,  still,  moist  day  in  summer  become  almost  intolerable. 

Generous  parks,  which  are  the  lungs  of  a  great  city,  should  be  scat- 
tered throughout  the  residential  and  business  sections;  playgrounds, 
boulevards,  and  small  open  areas  treated  as  parkings  not  only  beautify 
but  help  to  ventilate  a  city  and  add  to  the  comfort,  happiness,  and  health 
of  its  inhabitants. 

Natural  Ventilation. — Natural  ventilation  depends  upon  openings, 
such  as  doors  and  windows,  also  upon  the  air  that  comes  through  the 
pores  of  plaster,  brick,  and  stone  aiid  through  floors  and  ceilings  and 
through  the  cracks  and  crevices  about  window  frames,  etc. 

Natural  ventilation  depends  mainly  iipon  three  principal  factors: 
(1)  perflation  and  aspiration;  (2)  gravity  or  thermal  circulation;  (3) 
diffusion  of  gases.  These  factors  constantly  operate,  whether  in  the 
presence  or  absence  of  any  mechanical'  system.  In  fact,  most  schemes 
for  mechanical  ventilation  are  simply  an  application  of  these  natural 
forces. 

Perflation  is  simply  the  blowing  of  the  air  into  the  room  as  a  result 
of  the  movement  of  natural  air  currents.     Aspiration  is  the  sucking 


.  VENTILATION"  759 

action  of  the  wind  which  draws  air  out  of  a  space  that  it  is  blowing 
across.  Thus,  a  wind  blowing  across  an  open  tube  carries  along  with 
it  some  of  the  air  in  the  upper  part  of  that  tube.  This  causes  an  up- 
ward movement  of  the  air  in  the  tube.  The  same  phenomenon  takes 
place  when  wind  blows  by  a  window.  The  aspirating  action  of  air 
is  well  demonstrated  in  the  construction  of  an  ordinary  atomizer. 

The  air  is  kept  in  almost  constant  motion  through  changes  in  tem- 
perature. Warm  air  expands,  is  therefore  lighter,  and  rises.  This  is 
a  familiar  phenomenon  in  the  hot-air  balloon.  Thermal  circulation, 
though  often  imperceptible,  is  constantly  in  operation,  especially  in  oc- 
cupied rooms.  Even  in  calm  weather  there  is  considerable  ventilation 
owing  to  differences  in  temperature,  and  hence  differences  in  pressure  be- 
tween the  air  of  the  room  and  the  outside. 

More  air  than  is  commonly  supposed  enters  or  leaves  a  room  through 
the  cracks  about  doors  and  windows  and  other  crevices.  From  the 
standpoint  of  natural  ventilation  it  is,  therefore,  not  advisable  to  have 
windows  fit  too  snugly.  The  use  of  weather-strips,  tongue  and  grooved 
metal  strips,  and  similar  devices  to  keep  out  the  cold  air  saves  coal 
bills,  but  is  a  considerable  hindrance  to  natural  ventilation. 

Under  certain  conditions  very  considerable  amounts  of  air  pass 
through  the  building  materials  used  in  the  construction  of  walls,  floors, 
and  ceilings.  Ordinary  mortar  is  most  permeable,  then  comes  brick, 
then  sandstone,  next  plaster  of  paris,  while  enamel  and  tile  are  im- 
pervious. Under  a  pressure  of  108  millimeters  of  water  the  following 
amounts  of  air  pass  in  one  hour  through  one  square  meter  of: 

Mortar 3,264  liters 

Plaster  of  paris 146  " 

Bricks 312-1,396     " 

Sandstone 426-   496    " 

A  pressure  of  108  millimeters  of  water  is  equivalent  to  the  pressure 
of  a  strong  wind.  The  amount  of  air  that  will  pass  through  porous 
materials  varies,  of  course,  with  the  temperature,  moisture,  and  other 
factors. 

Marker  and  Schultze,  in  their  researches  on  the  spontaneous  ventila- 
tion of  stables,  found  that  the  following  interchange  of  air  occurred 
per  hour  over  one  square  yard  of  free  wall  at  9.5°  F.  difference  of 
temperature : 

With  walls  of  sandstone 4 . 7  cu.  ft. 

Quarried  limestone 6.5   "     " 

Brick • 7.9   "     " 

Tufaceous  limestone 10. 1   "     " 

Mud 14.4   «     " 

It  is  possible  to  force  sufficient  air  through  an  ordinary  brick  to 
deflect  the  flame  of  a  candle  on  the  other  side.     This  demonstration 


7G0 


VENTILATION  AND  HEATING 


Fig.  93. — Window  Ventilator. 


is  usually  accomplished  by  coating  the  edges  and  exposed  portions  of 
the  brick  with  sealing-wax  and  arranging  glass  funnels  on  either  side. 
Air  forced  with  a  bellows  through  one  funnel  may  be  measured  either 
as  to  its  amount  or  velocity  as  it  comes  out  of  the  opposed  funnel. 

Natural  ventilation  is  better  in  winter  than  in  summer,  owing  to 
greater  differences  in  temperature.  It  may  be  almost  nil  on  a  hot 
calm  day.  Too  much  moisture  in  the  air  of  a  room  settles  upon  the 
surfaces  and  thus  stops  the  pores  of  building  materials,  and  also  prevents 

the  escape  of  carbon 
dioxid.  Eain  has  a  sim- 
1'  ilar  effect  on  the  out- 
side. An  ordinary  brick 
will  soak  up  a  pint  of 
w  a  t  e  r.  Ventilation 
through  the  walls  is 
also  hindered  by  oil  and 
enamel  paints  and  by 
wall-paper.  Outside  ob- 
stacles, such  as  exces- 
sive foliage  and  nar- 
row streets,  are  also 
considerable  factors. 
Natural  ventilation  may  be  greatly  favored  by  simple  devices.  This 
may  be  demonstrated  by  placing  a  lighted  candle  in  a  bottle  with  a 
narrow  neck.  The  flame  soon  dies  out,  but  by  placing  a  partition  in 
the  neck  of  the  bottle,  so  that  the  products  of  combustion  will  escape 
on  one  side  and  the  fresh  air  enter  upon  the  other,  natural  ventilation 
proceeds  so  that  the  candle  remains  lighted.  There  are  numerous  simple 
devices  that  may  be  placed  at  the  top  or  bottom  of  windows  which  favor 
the  entrance  of  fresh  air  or  the  exit  of  vitiated  air.  An  arrangement 
shown  in  Fig.  93  gives  very  satisfactory  results.  One  of  the  upper 
window  panes  may  be  valved  or  fitted  with  a  fan  to  permit  the  entrance 
of  fresh  air  or  the  exit  of  vitiated  air.  Openings  in  ceilings,  ridged  ven- 
tilators, Sheringham's  valves,  Ellison's  bricks,  Tobin's  tubes,  and  Stev- 
ens' drawer-ventilator  are  all  useful  accessory  devices  to  aid  natural 
ventilation. 

Ellison's  bricks  are  bricks  with  conical  perforations,  the  widened 
end  of  the  conical  opening  debouching  on  the  interior  of  the  wall.  The 
holes  through  the  bricks  are  about  2/10  inch  in  diameter  externally 
and  11/4  inches  internally. 

Tobin's  tube  consists  of  a  large  upright  tube,  about  5  or  6  feet 
high,  which  conducts  outside  air  into  the  room  through  the  wall. 

The  Sheringham  valve  is  a  small  vertical  flap  door  in  the  wall  near 
the  ceiling,  balanced  by  a  counterpoise,  and  hinged  so  as  to  fall  forward 


VENTILATION 


761 


toward  the  room;  it  is  cased  in  at  the  sides  and  front,  so  that  the 
current  can  only  pass  upward. 

Stevens'  drawer  ventilator  is  like  a  drawer  lacking  its  back.  It  is 
made  to  fit  into  a  hole  in  the  wall  in  such  a  way  that  when  the  drawer 
is  shut  the  hole  is  airtight,  and  when  the  drawer  is  open  air  can  enter. 

Hinckes-Bird  ventilator  is  made  of  the  opening  between  two  ordi- 
nary window  sashes  when  the  lower  is  raised,  and  the  lower  opening 
closed  by  means  of  a  specially  high  sill  or  by  an  accurately  fitting  block 
of  wood. 


Fig.  94. — Diagrammatic  Sketch  of  Various  Provisions  for  Ventilation. — A,  Sash 
window  with  Hinckes-Bird's  arrangement.  B,  Hopper  sash-light  falling  inwards.  C, 
Louvred  outlets.  D.  McKinnell's  ventilator.  E,  Sheringham's  valve.  F,  Tobin's 
tube  (showing  valve  open).  G.  EHison's  conical  bricks.  H  and  I,  Grid  ventilators 
below  floor  joists.  (From  "Hygiene  and  Pubhc  Health,"  by  Drs.  L.  C.  Parkes  and 
H.  R.  Kenwood,  London,  H.  K.  Lewis,  Philadelphia,  Blakiston,  1911.) 


These  various  devices  should  be  protected  with  valves  so  that  they 
may  be  regulated.  Sometimes  it  is  advisable  to  provide  gauze  or  cot- 
ton filters  to  keep  out  the  dust. 

Natural  ventilation  is  greatly  aided  by  means  of  warming  the  air 
in  the  outlet  duct.  The  best  example  of  this  is  the  open  fireplace,  or 
other  devices  for  warming  the  air  in  outlet  tubes  already  referred  to. 

Wherever  possible,  open  windows  are  the  best  and  simplest  means 
of  ventilating  a  room.  Any  system  of  mechanical  ventilation  at  best 
is  costly  and  frequently  unsatisfactory.  Open  windows  are  cheap  and 
adequate,  but  the  limitations  and  disadvantages  of  natural  ventilation 


763  VENTILATION  AND  HEATING 

are  obvious,  and,  therefore,  we  are  frequently  required  to  resort  to 
mechanical  means. 

Mechanical  Ventilation. — All  "^artificial"  systems  of  ventilation  de- 
pend upon  one  of  three  methods:  (1)  plenum  system,  which  consists 
in  the  mechanical  propulsion  of  air  into  the  room;  (2)  the  vacuum 
system,  which  consists  of  the  mechanical  extraction  of  the  air  out  of 
the  room;  (3)  a  combination  of  the  plenum  and  vacuum  systems. 

Air  may  be  propelled  into  a  room  either  by  means  of  a  warming 
apparatus  or  by  mechanically  propelling  the  air  by  means  of  rotary  fans. 
Every  heating  apparatus  is  secondarily  a  ventilating  device,  especially 
hot-air  furnaces,  and  the  direct-indirect  systems  in  use  with  hot-water 
or  steam  pipes.  Stoves,  open  fireplaces,  and  similar  heating  arrange- 
ments are  also  good  ventilating  devices  in  that,  if  well  constructed,  they 
take  out  large  quantities  of  air  from  the  room. 

For  the  mechanical  propulsion  of  air  either  fans  or  "blowers"  are 
used.  These  may  be  run  by  electricity,  gas,  or  steam  power.  The  air 
is  forcibly  driven  through  ducts  to  where  it  is  wanted.  Without  this 
system  of  mechanical  ventilation  the  great  office  buildings,  basement 
restaurants,  large  passenger  steamships,  and  other  modern  structures 
would  not  be  habitable. 

If  dependence  is  placed  solely  upon  drawing  the  vitiated  air  out  of 
a  room  we  are  leaving  to  chance  where  the  fresh  air  is  coming  from 
to  replace  it.  In  other  words,  it  is  impossible  when  the  so-called  vacuum 
system  alone  is  used  to  control  the  source  of  the  fresh  air  and  insure 
its  purity.  Exhaust  systems  of  ventilation  are  therefore  of  value  only 
in  connection  with  a  positive  air  supply.  As  a  rule,  all  well-ventilated 
structures  depend  neither  upon  the  plenum  nor  the  vacuum  systems 
alone,  but  combine  the  two. 

The  disadvantages  of  the  mechanical  systems  of  ventilation  are  that 
they  are  expensive  as  to  first  installation  and  as  to  maintenance ;  further- 
more, they  are  designed  to  work  only  when  all  the  doors  and  windows 
are  kept  closed.  The  advantages  are  that  they  are  effective  in  all  kinds 
of  weather,  and  require  less  space  for  the  air  ducts  than  natural  ventila- 
tion. 

HEATING 

Heating  and  ventilation  go  hand  in  hand.  A  large  share  of  the 
cost  of  heating  is  chargeable  to  ventilation,  hence,  if  ventilation  is 
overdone,  it  is  an  unnecessary  expense.  The  artificial  warming  of 
houses  has  a  similar  action  to  clothing.  "Burning  fuel  in  the  furnace 
saves  fuel  in  the  human  machine."  It  especially  saves  the  strain  upon 
the  metabolism  of  the  young,  the  old,  and  the  feeble.  The  tendency 
in  winter  is  to  wear  too  much  clothing  indoors  in  order  to  compensate 


HEATING  763 

for  our  imperfect  systems  of  heating.  This  results  in  coddling — that 
is,  loss  of  vasomotor  tone  of  our  peripheral  capillary  circulation,  from 
the  constant  bathing  of  the  skin  in  a  close  moist  layer  of  air.  This  in 
turn  results  in  susceptibility  to  drafts  and  liability  to  colds.  It  is  quite 
unnecessary  to  wear  heavy  winter  clothing  in  rooms  and  offices  properly 
heated  and  ventilated. 

Most  of  our  American  houses  are  overheated  with  abnormally  dry 
air  in  the  winter  time.  This  is  a  mischievous  combination.  It  causes 
excessive  evaporation  from  the  skin  and  mucous  membranes,  which  gives 
rise  to  a  feeling  of  chilliness.  It  also  causes  dryness  of  the  skin  and 
mucous  membranes,  irritation  of  the  throat,  and  thus  predisposes  to 
colds  and  respiratory  infections.  Warm  dry  air  does  not  give  the  same 
sense  of  warmth  and  comfort  afforded  by  a  cooler  moist  air.  Thus,  air 
at  62°  to  65°  F.  and  a  relative  humidity  of  70  per  cent,  feels  warmer 
than  air  at  70°  to  72°  F.  and  a  relative  humidity  of.  50  per  cent,  or 
less.  Furnace  heat,  hot-water,  and  steam  pipes  tend  to  dry  the  air, 
and  thus  it  becomes  necessary  to  overheat  our  offices  and  houses  be- 
fore they  become  comfortable. 

Heat  is  measured  by  the  British  thermal  unit  (B.  T.  U.),  which  is 
the  quantity  of  heat  required  to  raise  the  temperature  of  a  pound  of  pure 
water  one  degree  at  its  point  of  maximum  density,  39°  F.  The  French 
thermal  unit  is  the  calorie  and  is  the  amount  of  heat  required  to  raise 
one  kilogram  of  water  one  degree  centigrade  at  corresponding  tempera- 
ture (4°  C).     One  calorie  equals  3.968  B.  T.  U. 

Heat  travels  by  radiation,  conduction,  and  convection.  All  three 
routes  are  constantly  in  operation  in  any  system  of  heating.  Thus,  with 
an  open  fireplace  the  heat  waves  radiate  in  straight  lines  to  the  nearest 
objects,  where  they  are  absorbed  or  reflected,  just  as  light  passes  through 
space  independent  of  the  atmosphere.  That  is  why  our  face  toasts  and 
our  back  freezes  before  an  open  fireplace.  The  heat  absorbed  by  any 
object  passes  through  that  object  from  particle  to  particle  by  conduc- 
tion. Most  metals  are  good  conductors;  air  is  a  very  poor  conductor 
of  heat.  Convection  is  the  process  by  which  heat  is  communicated 
through  gases  and  liquids  as  a  result  of  their  mobility.  Thus,  the  air 
is  warmed  by  our  bodies,  by  hot-water  pipes,  and  by  all  heated  objects, 
and  therefore  rises  and  establishes  convection  currents. 

There  are  five  main  methods  of  heating:  (1)  open  fires;  (2)  stoves; 
(3)  hot  air;  (4)  hot-water  or  steam  pipes;  (5)  electricity.  The  con- 
trol of  the  temperature  of  a.  building  is  more  a  question  of  management 
than  of  the  system  used. 

Open  Fires. — The  open  fireplace  heats  mainly  through  direct  radia- 
tion. It  has  the  advantage  of  being  cheerful  and  a  good  ventilator. 
It  has  the  disadvantage  of  being  wasteful  and  very  unequal  if  depended 
upon  as  the  chief  source  of  heat. 


764  VENTILATION  AND  HEATING 

Parkes  and  Kenwood  estimate  that,  in  an  ordinary  medium-sized  sit- 
ting room  with  an  ordinary  fire,  from  10,000  to  15,000  cu.  ft.  of  air 
are  drawn  up  the  chimney  in  an  hour,  the  current  being  generally 
from  3  to  6  ft.  a  second.  "As  ventilating  agents,"  say  Notter  and 
Firth,  "the  best  types  of  open  fireplace  cause  some  2,600  cu.  ft.  of  air 
to  pass  up  the  fiue  per  pound  of  coal  consumed,  or  the  passage  of  about 
18,000  cu.  ft.  up  the  chimney  per  hour." 

Franklin  Stoves. — Franklin  stoves  consist  of  coal  fires  in  a  cast-iron 
stove,  the  products  of  combustion  being  carried  off  through  a  stove- 
pipe. Such  stoves,  standing  free  in  the  room,  are  very  efficient,  so  far 
as  heating  is  concerned,  and  also  favor  ventilation  through  the  circu- 
lation of  air,  which  is  drawn  into  the  stove  to  support  the  burning  of 
the  fuel.  The  heating  of  the  room  is  unequal,  as  it  depends  largely 
upon  radiation  and  somewhat  upon  convection.  Such  stoves  are  apt 
to  become  red-hot,  in  which  case  it  is  believed  they  allow  carbon 
monoxid  to  pass  through  the  cast  iron.  The  organic  dust  in  the  air 
falling  upon  the  hot  stove  is  burned  and  produces  an  unpleasant  smell. 

Open  Gas  Heaters. — Open  gas  heaters  without  flues  to  carry  off  the 
products  of  combustion  are  bad,  from  a  sanitary  standpoint.  These 
heaters  consist  of  a  series  of  metal  tubes  containing  air  or  water,  which 
are  heated  with  naked  flames.  The  heat  is  thus  imparted  to  the  room 
by  convection  and  also  by  radiation.  Such  devices  may  contaminate  the 
air  with  carbon  monoxid  from  leakage  or  from  unconsumed  gas,  or  from 
the  formation  of  soot,  which  becomes  incandescent.  Such  heaters  also 
contaminate  the  room  with  COo  and  other  products  of  combustion. 
The  "rubber"  tube  feeding  these  gas  heaters  often  leaks,  and  there  is 
frequently  a  perceptible  odor  of  gas  in  rooms  where  these  devices  are 
used.  Open  heaters  burning  oil  are  less  objectionable  than  those  using 
gas. 

Hot-air  Furnaces. — A  hot-air  furnace  consists  of  a  coal  fire  which 
heats  a  series  of  tubes  or  plates  in  the  dome  of  the  furnace.  The  air, 
which  is  usually  taken  from  the  outside  through  a  duct,  flows  into  this 
dome,  where  it  comes  in  contact  with  very  hot  surfaces,  and  is  thus 
conducted  by  thermal  circulation  through  a  series  of  duets  into  the 
rooms  of  the  house.  A  hot-air  furnace  of  this  kind  constantly  pumps 
fresh  air  into  the  house  and  is,  therefore,  a  very  efficient  system  of 
ventilation.  The  objection  to  the  hot-air  furnace  is  that  the  air  is  ex- 
cessively dry  and  frequently  partly  "burned"  in  passing  over  the  heated 
surfaces  in  the  dome.  The  odor  caused  by  the  burning  of  the  organic 
particles  in  the  air  may  frequently  be  noticed  in  houses  heated  with  a 
hot-air  furnace.  The  heated  air  entering  the  rooms  is  usually  allowed 
to  escape  as  it  will.  In  order  to  overcome  the  disadvantage  of  the  dry- 
ness of  the  air  furnished  by  the  hot-air  furnace,  water  pans  are  always 
provided,  from  which  the  water  is  supposed  to  evaporate.     These  pans 


HEATING  765 

are  ridiculously  small  and  canuot  possibly  furnish  sufficient  moisture 
for  the  great  volume  of  air  constantly  passing  through  one  of  these 
furnaces.  For  instance,  according  to  Harrington,  air  at  25°  F.  satu- 
rated with  moisture  and  then  heated  to  70°  F.  would  need  half  a  pint 
in  every  thousand  cubic  feet  to  give  it  a  humidity  of  65  per  cent.  In- 
gersoll  calculates  that  a  house  containing  17,000  cu.  ft.  of  space  would 
require  for  a  relative  humidity  of  40  per  cent,  at  70°  F.  in  the  air  already 
containing  20  per  cent,  humidity  and  changed  once  an  hour,  about  15 
gallons  of  water  a  day.  The  little  water  pockets  in  the  average  hot  air 
furnace  are  insignificant  and  inadequate. 

The  air  from  a  hot-air  furnace  is  perhaps  drier  than  that  furnished 
by  any  other  system  of  heating  or  ventilation.  Thus,  an  out-of-door  air 
in  winter  at  a  temperature  of  0°  F.,  with  a  relative  humidity  of  50  per 
cent.,  when  heated  to  70°  F.,  will  have  a  relative  humidity  of  only 
3  per  cent.  This  is  drier  than  the  air  of  the  driest  climate  known, 
which  is  seldom  less  than  30  per  cent.  It  is  not  unusual  for  the  ex- 
cessively dry  air  of  a  furnace-heated  house  to  cause  the  woodwork  to 
shrink  and  fall  apart,  the  bindings  of  books  to  crack,  etc.  Living  in 
such  an  atmosphere  is  not  normal  and  must  be  harmful. 

Hot-water  and  Steam  Pipes. — This  is  a  very  simple  and  effective 
system  of  heating  buildings.  The  hot-water  system  is  especially  ap- 
plicable to  small  buildings  and  steam  pipes  to  large  buildings.  The 
hot  water  is  more  readily  controllable  than  steam,  which  has  a  ten- 
dency to  overheat.  Special  furnaces  are  found  on  the  market  to  heat 
the  water  or  to  generate  the  steam,  which  then  circulates  through  pipes 
to  the  rooms  where  wanted.  If  the  hot-water  radiators  or  steam  coils 
are  exposed  directly  in  the  room,  the  system  is  known  as  the  "direct.-" 
In  the  direct-indirect  system  the  hot-water  pipes  or  steam  coils  are 
placed  in  a  special  box  where  the  air  from  the  outside  is  heated,  and 
this  heated  air  flows  by  thermal  circulation  through  ducts  into  the  rooms 
where  wanted.  In  the  direct  system  the  air  of  the  room  is  simply  heated 
and  reheated  over  again,  while  in  the  direct-indirect  system  the  fresh 
warmed  air  is  constantly  pumped  into  the  building  and  it  is,  therefore, 
an  efficient  method  of  ventilation.  In  both  these  systems  the  air  is 
abnormally  dried,  just  as  it  is  in  the  hot-air  furnace,  though  not  to 
the  same  degree. 

Electric  Heating. — Electric  heating  is  clean,  easily  regulated,  but 
expensive.  It  has  the  disadvantage  of  being  insufficient  as  a  ventilat- 
ing device,  unless  special  inlets  and  outlets  are  provided.  Electric 
heaters  consist  simply  of  resistance  coils  which  heat  the  room  mainly 
through  radiation  and  convection. 

Tlie  Cooling  of  Rooms. — Much  attention  has  been  given,  through 
necessity,  to  the  heating  of  rooms  in  winter  time,  but  heretofore  little 
attention  has  been  given   to  the  cooling  of  rooms  in  the  hot  season. 


766  VENTILATIOlSr  AND  HEATING 

It  is  quite  as  practicable  to  cool  rooms  as  it  is  to  heat  them,  and  some- 
times quite  as  important  to  health. 

The  principle  of  practically  all  cooling  devices  depends  upon  the 
fact  that  when  a  fluid  evaporates  to  its  gaseous  state  it  absorbs  a  con- 
siderable amount  of  heat — latent  heat.  This  heat  is  taken  from  the 
surrounding  objects  which,  therefore,  become  correspondingly  cold.  Cold 
may  also  be  produced  by  the  expansion  of  air.  This  was  pointed  out  in 
1845  by  Joule.  Thus,  if  a  jet  of  air  at  60°  F.  were  blown  into  a  room 
under  a  pressure  of  10  inches  of  mercury  above  the  ordinary  barometric 
pressure,  the  sudden  expansion  of  this  compressed  air  would  reduce 
it  to  a  theoretical  temperature  of  13.3°  Y.  below  freezing.  This  prin- 
ciple of  dynamic  cooling  has  been  applied  to  refrigerators. 

Ammonia  gas  is  now  almost  universally  employed  in  freezing  ma- 
chines. This  gas  is  readily  condensed  into  a  liquid.  The  compressed 
gas  is  allowed  to  expand  into  tubes,  and  the  cold  thus  produced  utilized 
directly;  more  frequently  an  indirect  method  is  used  by  which  the  ex- 
panding gas  first  cools  a  freezing  mixture  consisting  of  a  saturated  solu- 
tion of  calcium  chlorid;  this  chilled  brine  is  then  pumped  through  a 
series  of  pipes  to  the  refrigerator  or  apartment  where  it  is  desired. 
Humidifiers  and  air  washers  are  also  used  to  cool  rooms  and  buildings. 

A  simple  method  of  cooling  a  room  is  by  the  rapid  evaporation  of 
water.  Dr.  Manning  was  able  satisfactorily  to  cool  a  large  room  in  the 
Government  Printing  Office  at  Washington  by  blowing  air  by  means 
of  an  electric  fan  over  a  moist  sheet.  This  sheet,  about  a  yard  wide, 
was  hung  near  the  ceiling,  and  constantly  wetted  by  a  stream  of  water 
flowing  over  it. 

EEFERENGBS 

Ward,  E.  D. :  Climate,  Considered  Especially  in  Relation  to  Man.  Put- 
nam, N.  Y.,  1908. 

Richards,  E.  H.,  and  Woodman,  A.  G. :  Air,  Water  and  Food.  Wiley  & 
Sons,  N.  Y.,  1900. 

Moore,  W.  L. :    Descriptive  Meteorology.    D.  Appleton  &  Co.,  N.  Y.,  1911. 

Macfie,  D.  C. :    Air  and  Health.    E.  P.  Dutton  &  Co.,  1909. 

Carpenter,  R.  C. :    Heating  and  Ventilation  of  Buildings,  1915. 

Hoffman,  J.  D.,  and  Raber,  B.  F. :  Handbook  for  Heating  and  Ventilating 
Engineers,  1913. 


SECTION  V 
SOIL 

CHAPTER  I 
GENERAL  CONSIDERATIONS 

The  upper  layer  of  the  earth's  crust,  known  as  the  soil,  is  derived 
from  the  disintegration  of  rocks  and  the  decay  of  animal  and  vegetable 
matter  of  all  kinds.  It  varies  from  a  few  inches  in  depth  to  several 
feet.  The  sub-soil  also  varies  from  a  few  feet  to  hundreds  of  feet  in 
depth,  to  hard  pan  or  an  impermeable  stratum. 

From  a  sanitary  standpoint  the  soil  must  be  regarded  as  our  friend 
rather  than  our  enemy.  Enormous  quantities  of  organic  matter  and 
infections  of  all  kinds  find  their  iinal  resting  place  in  the  soil  and 
are  there  disposed  of  and  rendered  harmless  by  nature's  beneficent  proc- 
esses. In  fact,  a  closer  study  of  the  functions  of  the  superficial  layer 
of  the  soil  shows  that  it  is  not  only  the  organ  of  digestion  and  respira- 
tion of  the  earth,  but,  like  the  liver,  it  is  the  great  organ  in  which  toxic 
substances  of  all  kinds  are  neutralized  or  destroyed. 

The  sanitarian  does  not  look  upon  the  soil  as  dead  and  inert,  but 
rather  as  a  living  being,  for  it  presents  many  of  the  vital  phenomena 
that  characterize  life :  digestion,  metabolism,  assimilation,  growth,  res- 
piration, motion,  and  even  reproduction.  The  soil  breathes,  it  absorbs 
oxygen  and  exhales  carbon  dioxid;  it  is  capable  of  digesting  and  as- 
similating vast  amounts  of  organic  matter  by  a  complex  process  of 
metabolism;  the  waste  products  are  excreted.  If  these  wastes  are  re- 
tained the  soil  may  be  choked  or  killed  by  an  accumulation  of  its  own 
poison — a  sort  of  autointoxication.  The  soil,  like  all  living  things,  de- 
mauds  water,  but  it  may  be  drowned  by  an  excess.  A  water-logged  soil 
dies  in  very  much  the  same  sense  that  an  individual  dies  who  has  sup- 
pression of  urine.  Sedgwick  speaks  of  the  "living  earth"  in  the  sense 
that  it  is  teeming  with  life;  bacteria,  molds,  amebae,  and  many  of 
the  primitive  forms  of  the  animal  kingdom,  as  well  as  worms,  insects, 
snakes,  birds,  rodents,  and  many  other  animals,  make  their  temporary  or 
permanent  homes  in  the  upper  layers  of  the  earth.  Earth  worms  by 
their  plowing  action,  so  beautifully  shown  by  Darwin  in  1881,  constantly 
turn  over  the  upper  layers  of  the  earth.     The  soil,  therefore,  is  in  con- 

767 


768  GENERAL  CONSIDERATIONS 

stant  peristalsis,  which  helps  its  digestive  fuiK'tions.  The  rise  and  fall 
of  the  ground  water  is  analogous  to  the  movements  of  the  diaphragm  and 
assists  the  respiratory  functions  of  the  soil. 

Classification  of  Soils. — Soils  are  variously  classified,  depending  upon 
the  amount  of  sand,  gravel,  clay,  loam,  humus,  peat,  muck,  rock,  alkali, 
etc.,  which  they  contain.  The  difference  between  a  sandy  and  gravelly 
soil  depends  mainly  upon  the  size  of  the  particles.  These  soils  interest 
the  sanitarians  because  hookworms  live  and  flourish  in  them  better  than 
they  do  upon  clay  or  rock  formation.  "Clay  exists  in  particles  of  the 
smallest  possible  size.  It  is  very  cohesive,  possesses  a  high  degree  of 
plasticity,  and  plays  a  very  important  part  in  determining  the  fertility 
of  soils,  their  texture,  and  their  capacity  for  holding  water.  Its  plasticity 
is  due  to  the  presence  of  a  small  proportion  of  hydrated  silicate,  and  is 
modified  very  greatly  by  the  addition  of  less  than  a  hundredth  part  of 
caustic  lime.  It  is  exceedingly  impermeable  to  water,  and  when  wet  dries 
with  great  slowness"  (Harrington).  Loam  consists  of  a  mixture  of 
sand,  clay,  and  humus.  If  the  sand  predominates  the  soil  is  said  to  be 
light;  if  the  clay  predominates,  heavy.  A  rich  soil  contains  an  abun- 
dance of  humus. 

By  humus  is  meant  the  products  of  vegetable  decomposition  in  their 
various  intermediate  stages  of  decay.  It  is  the  essential  element  of 
vegetable  mold,  and  is  necessarily  of  most  complex  composition.  It  is 
composed  of  a  great  number  of  closely  related  definite  chemical  com- 
pounds.^ Humus  contains  a  high  percentage  of  nitrogen,  especially 
marked  in  some  of  our  prairie  soils  and  in  the  "black  soil"  found  in 
the  provinces  of  the  Ural  Mountains,  which,  according  to  von  Hensen, 
contains  as  much  as  from  5  to  12  per  cent,  of  organic  matter. 

Surface  Configuration. — Geodesy,  or  surface  configuration,  has  an 
important  relation  to  health.  Low  and  swampy  ground  is  a  breeding 
place  for  the  malarial  mosquito.  Highlands  are  apt  to  be  drier  and 
more  healthful  than  lowlands.  A  slope  affords  better  drainage  than 
flat  lands,  and  thus  diminishes  the  dangers  from  soil  pollution,  but  in- 
creases the  risk  of  infection  being  washed  down  from  those  living  above. 
In  narrow  valleys  the  air  stagnates,  the  moisture  is  excessive  in  both 
the  soil  and  the  air,  and  there  is  an  unpleasant  blanket  of  cold  layers 
of  air  at  night.  Mountain  sides  are  notoriously  windy.  High  plateaux 
suffer  from  extremes  of  temperature.  Thus,  at  Mexico  City  (about 
8,000  feet  above  sea  level)  there  is  a  sharp  contrast  between  the  tem- 
perature during  the  day  and  night,  and  even  during  the  daytime  be- 
tween the  sunshine  and  the  shade.  At  Quito,  which  is  9,350  feet  above 
the  sea  level,  the  daily  variation  of  temperature  at  some  periods  of  the 
year  is  no  less  than  34°  F.  Northern  exposures  do  not  get  enough  sun- 
shine, and  southern  exposures  sometimes  too  much. 

*See  Bulletins  of  the  Bureau  of  Soils,  Dept.  of  Agriculture. 


GENERAL  CONSIDERATIONS  769 

The  relation  of  the  surface  configuration  of  the  land  to  health  is 
intimately  interwoven  with  the  whole  question  of  climate,  and  must 
take  into  consideration  temperature,  air  movements,  humidity,  sun- 
shine, barometric  pressure,  precipitation,  and  the  seasons  with  their 
endless  varieties  froni  tropical  to  arctic. 

Composition  of  the  Soil. — Much  attention  was  formerly  given  to  the 
hygienic  importance  of  the  chemical  constituents  of  the  soil.  The  pres- 
ence of  organic  substances  was  regarded  not  only  with  suspicion,  but  even 
as  a  serious  menace  to  health.  It  was  claimed  that  organic  pollution 
of  the  soil  made  a  good  culture  medium  for  the  germs  of  infectious 
diseases.  The  gaseous  products  of  decomposing  organic  matter  in  the 
soil  have  long  been  looked  upon  as  particularly  injurious.  These  gases, 
with  other  ill-defined  but  unknown  volatile  substances,  are  spoken  of 
as  miasma  or  effluvia. 

We  now  know  that  very  few,  if  any,  of  the  bacteria  pathogenic  for 
man  grow  and  multiply  in  the  soil  under  natural  conditions.  The  spores 
of  tetanus,  malignant  edema,  and  anthrax  may  live  in  garden  earth  for 
many  years,  but  it  is  doubtful  whether  these  microorganisms,  especially 
the  anaerpbes,  ever  find  conditions  favorable  for  growth  and  multiplica- 
tion in  the  soil.  Ordinarily  typhoid,  dysentery,  and  cholera  bacilli  do 
not  flourish  in  the  soil;  on  the  contrary,  they  soon  die  there.  It  has 
been  shown  that  cities  built  upon  polluted  soils  have  sometimes  suffered 
relatively  less  from  typhoid  and  cholera  than  cities  built  upon  rocky 
or  virgin  soil.  In  some  cities  (as  Budapest)  it  has  been  pointed  out 
that  the  greatest  morbidity  and  mortality  rate  was  in  that  part  of  the 
city  built  upon  made  ground  filled  in  with  trash  and  much  organic 
waste.  These  instances  have  been  largely  coincidences,  for,  as  a  rule, 
the  low-lying,  polluted  soil  happened  to  be  the  poor,  crowded  tenement 
district.  A  sanitarian  does  not  recommend  polluted  soils  for  building 
sites,  but  it  seems  that  their  influence  upon  health  has  been  overstated, 
especially  where  cellars  are  properly  constructed.  While  a  polluted  soil 
may  not  be  hazardous  in  the  ways  just  indicated,  it  may  be  dangerous 
so  far  as  hookworms  and  other  parasites  are  concerned,  or  indirectly  it 
may  lead  to  contamination  of  drinking  water,  food,  etc.  See  "Pollution 
of  the  Soil,"  page  779. 

Mineral  Matters  in  the  Soil. — By  far  the  most  abundant  ele- 
ment in  the  soil  is  oxygen.  According  to  various  estimates,  from  33  to 
50  per  cent,  of  the  solid  crust  of  the  earth  consists  of  oxygen.  The  other 
elements  found  in  abundance  in  the  soil  are :  silicon,  carbon,  sulphur, 
hydrogen,  chlorin,  phosphorus,  fluorin,  aluminium,  calcium,  magnesium, 
potassium,  sodium,  iron,  manganese,  and  barium.  Aluminium  silicate 
or  clay  makes  up  perhaps  two-thirds  of  the  inorganic  components  of  soils. 
Other  compounds  are  lime  and  magnesia  carbonates  (limestone)  and  nu- 
merous chlorids,  sulphates,  phosphates,  oxids,  etc.,  of  the  various  bases. 
26 


770  GENEPtAL  CONSTDETIATTOXS 

Iron  is  universally  present  and  gives  tlie  red  color  to  soils.  Nitrogen 
exists  in  soils  in  three  distinct  forms:  (1)  protein  and  its  split  products, 
(2)  ammonia  and  its  salts,  and  (3)  nitric  acid  and  nitrates  or  nitrous 
acids  and  nitrites. 

Vegetable  Matter  in  the  Soil. — The  vegetable  matter  exists  in 
the  soil  in  various  stages  of  decomposition.  One  result  of  the  decay 
of  vegetable  substances  is  the  formation  of  organic  acids,  which  have 
considerable  power  to  dissolve  mineral  substances,  accounting  in  part  for 
the  plumbosolvent  action  of  acid-reacting  surface  waters  from  swampy 
lands. 

Peat  or  niuck  results  from  the  incomplete  decay  of  vegetable  matter 
under  water. 

Animal  Matter  in  the  Soil. — Organic  matter  of  animal  origin  in 
soils  results  chiefly  from  the  decomposition  of  carcasses  or  from  con- 
tamination with  the  excreta  of  animals.  As  a  rule,  animal  matter  is 
neither  so  abundant  nor  so  widely  distributed  in  the  soil  as  vegetable 
matter.  From  a  sanitary  standpoint  soils  polluted  with  organic  matter 
of  animal  origin  present  a  greater  danger  than  soils  polluted  with  vege- 
table matter. 

Physical  Properties. — In  general  it  may  be  said  that  the  physical 
properties  of  a  soil  are  more  important,  from  the  standpoint  of  health, 
than  its  chemical  composition. 

Porosity. — By  the  porosity,  or  pore  volume,  of  a  soil  is  meant  the 
volume  of  the  interstices  between  the  particles,  which  may  be  filled  with 
water  or  air,  or  both ;  in  other  words,  the  power  to  absorb  water.  Poros- 
ity is  expressed  as  a  percentage  of  the  whole  mass.  Ordinarily  the  pore 
volume  in  soil  amounts  to  about  forty  per  cent. ;  some  apparently  com- 
pact masses,  such  as  sandstone,  have  as  much  as  thirty  per  cent.  The 
pore  volume  of  the  soil  is  independent  of  the  size  of  the  individual 
grains. 

Permeability. — The  permeability  of  a  soil  is  its  ability  to  allow 
the  passage  of  water ;  it  does  not  depend  upon  the  pore  volume,  but  upon 
the  size  of  the  individual  pores.  Eocks  may  have  a  high  porosity,  but 
slight  permeability,  due  to  the  extreme  fineness  of  the  pores.  Clay  has 
a  high  porosity,  but  its  permeability  is  slight,  owing  to  the  extremely 
small  size  of  the  pores,  although  their  aggregate  capacity  is  rather  large. 
The  presence  of  fissures  and  joints  in  the  rock  will  greatly  increase  its 
transmitting  power. 

Water  Capacity. — The  water  capacity  of  the  soil  is  the  amount 
of  water  held  in  the  interstices  of  the  soil  when  saturated,  Avhile  the 
water-retaining  capacity  is  the  amount  of  water  held  back  after  a  satu- 
rated soil  is  drained. 

Soil  Temperature.— The  sun  is  the  principal  source  of  the  soil 
temperature.     Some  heat  is  produced  from  chemical  changes,  but  not 


GENEEAL  CONSIDEEATIONS  771 

in  considerable  amounts.  The  original  heat  of  the  earth's  interior  fur- 
nishes a  constant  source  of  heat  that  is  of  much  importance. 

The  heat  absorbed  and  given  off  by  the  soil  has  a  notable  influence 
upon  the  atmospheric  temperature.  Some  soils  and  moist  surfaces  absorb 
heat  from  the  sun  and  give  it  off  again  when  the  sun  has  set.  The  most 
heat-absorbent  soils  are  sandy  soils.  The  sand  of  the  desert  may  be  heated 
to  200°  F.,  and  when  this  hot  sand  is  raised  by  simoons  the  tempera- 
ture of  the  air  in  the  shade  may  reach  125°  F.  or  more.  The  power 
of  absorbing  or  reflecting  solar  heat  also  depends  upon  the  color  of  the 
soil. 

Adsorption. — The  soil  has,  to  a  remarkable  extent,  the  property  of 
adsorbing  odors  and  gases,  and  ordinarily  it  is  very  hygroscopic.  The 
soil  is  also  capable  of  holding  toxins,  colors,  and  other  substances 
through  the  physico-chemical  property  of  adsorption.  In  this  respect 
it  acts  like  charcoal.  Illuminating  gas  from  leaky  mains  may  be  divested 
of  its  odorous  constituents  in  its  passage  through  the  soil,  so  that  its 
presence  in  houses  may  be  undetected,  thereby  greatly  increasing  the 
danger.  In  the  experiments  made  by  Abba,  Orlandi,  and  Eondelli 
about  the  filtering  galleries  of  the  Turin  water  supply  the  property  of 
the  soil  to  hold  back  substances  ni  solution  was  shown.  Cultures  of 
Bacillus  prodigiosus  in  large  volumes  of  water  poured  into  the  ground 
at  various  points  made  their  appearance  200  meters  away  in  42  hours, 
whereas  dyes,  such  as  methyleosin  and  uranin,  could  not  be  detected 
until  after  75  hours. 

3oil  Air. — Air  is  present  in  all  soils,  even  in  the  hardest  rocks.  Sand- 
stone may  contain  from  20  to  40  per  cent.,  sand  from  40  to  50  per  cent., 
and  humus  as  much  as  2  to  10  times  its  own  bulk.  The  soil  air  differs, 
markedly  in  composition  from  that  of  the  atmosphere.  It  is  Usually 
very  moist  and  contains  various  gases,  especially  carbon  dioxid,  :fesult- 
ing  from  the  decomposition  of  organic  matter.  For  the  same  reason 
soil  air  contains  less  oxygen  than  the  free  atmosphere.  The  soil  air 
varies  greatly,  according  to  the  character  of  the  soil,  the  climate,  the 
season,  and  rainfall.  There  is  a  continual  interchange  between  the  air 
of  the  soil  and  the  air  of  the  atmosphere.  This  interchange  is  influ- 
enced by  differences  in  temperature,  by  rainfall,  and  by  the  movements 
of  the  ground  water  and  by  barometric  pressure.  Eain  chokes  the  pores 
and  checks  soil  ventilation.     The  soil  air  is  in  constant  motion. 

Following  the  teachings  of  Pettenkofer,  the  amount  of  carbon  dioxid 
in  the  soil  air  was  for  years  taken  as  an  index  of  the  amount  of  soil 
pollution.  It  is  now  well  known,  however,  that  this  is  not  a  reliable 
index,  for  the  reason  that  many  conditions  influence  the  amount  of  COo 
in  soil  air.  A  soil  recently  manured  may  contain  from  2  to  5  or  even  10 
parts  of  COg  per  thousand.  In  a  gravelly  soil  the  proportion  may  be 
as  high  as  80  parts  per  thousand. 


772  GENEEAL  CONSIDEEATIONS 

Soil  air  may  influence  health  when  contaminated  with  poisonous 
gases,  such  as  carbon  monoxid.  This  occasionally  happens.  In  the  open 
these  gases  would  be  so  greatly  diluted  that  they  could  scarcely  exert 
a  deleterious  influence,  but  when  concentrated,  as  they  sometimes  are 
in  dwellings,  and  breathed  for  a  long  period  of  time  they  may  be  re- 
sponsible for  anemia,  headache,  and  other  symptoms.  Soil  air  contain- 
ing carbon  monoxid  may  be  sucked  into  a  dwelling  from  long  distances 
in  a  lateral  direction.  Leaky  gas  pipes  m.ay  thus  render  the  air  of  a 
dwelling  impure  if  the  cellar  is  permeable.  This  is  favored  by  the 
pumping  action  of  the  furnace,  especially  when  the  surface  of  the  ground 
is  frozen. 

Soil  air  is  practically  sterile;  that  is,  under  ordinary  conditions  it 
contains  few  bacteria.  Odors  sometimes  contained  in  the  air  from  a 
polluted  soil  have  no  known  injurious  efl'ect. 

Soil  Water. — The  passage  of  water  through  the  soil  is  essential  to 
soil  activity.  The  moisture  favors  the  bacterial  growth  by  which  soils 
purify  themselves  and  favors  vegetation.  Nitrates,  chlorids,  and  other 
soluble  substances  are  dissolved  in  the  water  and  pass  into  the  sub- 
soil, or  furnish  food  to  the  roots  of  plants.  A  soil  absolutely  dry,  as 
a  desert  soil,  is  lifeless.  A  soil  with  an  excess  of  moisture,  that  is, 
one  in  which  the  ground  water  level  is  at  or  near  the  surface,  delays  and 
alters  the  natural  decomposition  of  organic  matter.  In  the  deeper  layers 
of  the  soil,  where  no  bacterial  action  takes  place,  vegetable  matter  may 
remain  almost  permanently  without  change.  Thus,  wooden  piles  are 
not  attacked  after  centuries. 

Water  exists  in  the  soil  in  two  principal  forms:  (1)  soil  moisture, 
which  comprises  the  water  present  in  the  interstices  of  the  upper 
partly  saturated  layer,  as  well  as  the  watery  vapor  contained  in  the 
soil  air,  and  (2)  ground  water,  or  sub-soil  water,  in  which  case  the  in- 
terstices of  the  soil  are  completely  filled. 

The  soil  moisture  is  estimated  by  determining  the  loss  of  weight  by 
drying  10  grams  of  soil  at  100°  C.  to  constant  weight.  The  dry  sample 
may  then  be  exposed  to  air  saturated  with  moisture  under  a  bell  Jar 
and  again  weighed.  The  increase  in  weight  indicates  the  absorptive 
power  of  the  soil. 

Water  may  also  be  regarded  as  existing  in  the  soil  under  three 
conditions,  viz.,  hygroscopic,  capillary,  and  gravitation.  The  hygro- 
scopic water  is  that  which  adheres  to  the  surface  of  the  soil  particles 
in  the  presence  of  air.  The  capillary  moisture  is  that  which  is  held 
within  the  spaces  that  are  capillary  in  their  nature.  The  gravitation 
water  is  that  which  drains  through  the  soil  and  accumulates  in  the  sub- 
soil over  an  impermeable  stratum.  For  a  discussion  of  ground  water 
see  chapter  on  Water. 

It  is  generally  stated  that  a  persistently  low  ground  water  level, 


GENEEAL  CONSIDERATIONS  773 

viz.,  15  to  20  feet,  is  liealtliful,  and  that  a  persistently  high  ground 
water  level,  viz.,  3  to  5  feet,  is  mihealthful,  and  that  a  ground  water 
level  that  fluctuates  suddenly  is  still  more  unhealthful.  Pettenkofer 
found  that  typhoid  fever  was  more  likely  to  occur  at  Munich,  Berlin, 
and  Leipzig  when  the  ground  water  level  was  at  its  lowest.  His  ex- 
planations to  account  for  this  were  ingenious,  but  we  now  know  that 
the  relation  was  only  a  coincidence,  for  the  same  does  not  hold  in  other 
places. 

Subsoil  drainage  is  usually  considered  more  of  an  agricultural  neces- 
sity than  a  public  health  question.  Large  tracts  of  our  land  in  the 
middle  West  and  in  other  parts  of  the  world  have  normally  a  high 
ground  water  level,  and  it  is  necessary  to  bring  this  down  in  order  to 
increase  the  fertility  of  the  soil.  This  is  done  by  draining  the  subsoil, 
which  also  abolishes  marshy  and  swampy  lands,  and  thus  puts  a  check 
upon  malaria. 

One  of  the  principal  influences  of  the  soil  upon  general  health  is 
through  soil  moisture.  Dampness  in  or  near  the  surface  of  the  soil 
may  affect  the  health  of  those  dwelling  nearby.  Such  a  soil  is  cold, 
and  the  atmosphere  immediately  above  it  is  liable  to  be  damp,  and  this 
appears  to  conduce  to  rheumatism,  neuralgia,  and  diseases  of  the  res- 
piratory tract.  Investigations  seem  to  indicate  that  the  general  health 
of  those  dwelling  on  damp  soils  is  iiiferior  to  that  of  those  more  favor- 
ably circumstanced  in  that  regard. 

The  Nitrogen  Cycle. — The  most  interesting  of  the  vital  phenomena 
taking  placing  in  the  soil  is  the  disposal  and  utilization  of  organic  mat- 
ter. This  may  best  be  illustrated  by  the  nitrogen  cycle,  which  must  be 
understood  in  order  to  have  a  clear  conception  of  soil  pollution,  water 
purification,  and  sewage  disposal. 

The  nitrogen  cycle  is  a  complex  series  of  events  which  protein  mat- 
ter undergoes,  in  which  it  is  reduced  to  simple  and  stable  inorganic 
compounds,  and  then  returns  through  plant  life  to  the  animal  kingdom. 
One  phase  of  the  cycle,  namely,  the  breaking  down  of  animal  and 
vegetable  matter,  is  due  almost  entirely  to  bacterial  action.  The 
other  phase,  namely,  the  building  up  of  complex  living  organic  matter 
from  simpler  compounds  and  elements,  is  mainly  a  function  of  living 
plants. 

The  nitrogen  cycle  is  a  process  in  which  the  anabolism  or  synthesis 
occurs  in  plants,  while  the  catabolism  or  analysis  is  brought  about 
chiefly  through  bacterial  action.  Hence  the  series  of  events  constituting 
the  nitrogen  cycle  largely  depends  upon  the  plant  kingdom.  The  im- 
portant phases  of  the  cycle  occur  upon  the  soil  and  in  its  superficial 
layer.  It  will  presently  be  seen  that  this  cycle  has  a  fundamental  im- 
portance in  sanitary  science,  and  has  a  special  significance  in  prevent- 
ing soil  pollution,  in  the  purification  of  water,  and  in  the  disposal  of 


774 


GENETJAL  CONSIDERATIONS 


sewage.     It  is  evident  iliat  any  permanent  break   in   lliis  (•y('Ie  would 
result  in  the  cessation  of  life  npon  the  earth. 

As  soon  as  an  animal  or  plant  dies  its  protein  constituents  are  at 
once  attacked  by  putrefactive  bacteria.  The  proteolytic  microorganisms 
(aided  by  the  larvae  of  insects)  growing  in  and  upon  the  nitrogenous 
matter  break  it  up  into  secondary  and  simpler  products,  which  have 
a  striking  resemblance  to  the  cleavage  products  of  gastric  and  pancreatic 
digestion.  Some  of  the  putrefactive  bacteria,  of  which  the  Bacillus 
subtilis  and  the  Bacillus  proteus  are  important  types,  liquefy  protein 


/VO3  -tr"*!'" 

[.Kinetic  Energy] 
Fig.  95. — The  Nitrogen  Cycle. 


matter  during  the  process  of  putrefaction.  Other  bacteria,  of  which  the 
colon  bacillus  is  a  type,  break  down  organic  matter  without  evident 
liquefaction.  Very  many  other  species  of  bacteria  take  part  in  this 
stage  of  the  cycle.  Eor  the  most  part  the  microorganisms  pathogenic 
for  man  are  killed  during  the  process  of  putrefaction;  they  die  in  the 
struggle  for  existence.  The  processes  of  decomposition  are  essentially 
the  same,  whether  the  organic  matter  is  the  carcass  of  an  elephant,  a 
beetle,  a  tree,  or  a  leaf,  provided  that  the  necessary  moisture,  warmth, 
and  other  conditions  for  bacterial  growth  are  present.  The  breaking 
down  of  vegetable  matter  is  slower  and  more  difficult  than  the  break- 
down of  animal  matter.  This  is  due  in  part  to  the  fact  that  the  latter 
contains  larger  percentages  of  putrescible  protein  and  also  usually  con- 
tains more  moisture,  which  favors  bacterial  activity. 

The  breaking  down  of   the   complex  protein   molecules   to   simpler 
and  stabler  compounds  is  usually  spoken  of  as  mineralization,  and  may 


GENERAL  CONSIDERATIONS 


775 


be  regarded  as  a  series  of  oxidations.  According  to  our  present  chemi- 
cal conception,  it  is  really  a  series  of  hydrolyses.  The  complicated 
molecular  structure  of  protein  matter  is  analyzed  into  amino  com- 
pounds of  simpler  and  simpler  composition,  until  nitrogen  finally  ap- 
pears in  the  form  of  ammonia.  We  know  little  of  the  chemistry  of  the 
early  stages  of  protein  decomposition.  The  process  seems  hopelessly 
complicated  from  the  intricate  structure  of  the  molecule.  Eventually 
from  the  seething  caldron  of  molecular  disintegration  there  appear 
simpler  substances,  such  as  proteoses,  peptone,  ptomains,  amins,  leucin, 
and  tyrosin,  and  other  amino  substances,  as  well  as  organic  acids,  indol, 
skatol,  phenol,  and  finally  sulphuretted  hydrogen,  mercaptan,  carbonic 


Putrefaction   —  Danger  Zone 

Nitrification  —  NO  i—Rlshu  Zone 
NOi 


Final  Mineralization   NOz— Safe  Zone 
(Absence  of  NOo  and  NH^) 


iiroun  d^^Water  - 


Fig.  96. — The  Nitrogen  Cycle  in  Diagrammatic  Vertical  Section. 


acid,  and  ammonia.  One  of  the  final  products  of  the  process  is  carbon 
dioxid,  part  of  which  passes  into  the  atmosphere  and  part  of  which  is 
retained  in  the  soil  as  carbonates  of  alkalis  or  alkaline  bases.  The 
ammonia,  as  such,  cannot  be  used  by  plants.  Some  of  it  may  escape 
into  the  atmosphere,  but  for  the  most  part  it  is  retained  in  the  soil 
as  ammonium  chlorid  or  ammouiaim  carbonate.  In  the  soil  the  am- 
monia is  oxidized  by  tlie  action  of  nitrifying  bacteria  into  nitrates.  This 
nitrifying  action  of  bacteria,  elucidated  by  Winogradski  in  1888,  was 
one  of  the  brilliant  discoveries  in  bacteriology.  Through  his  work  and 
that  of  later  workers,  it  is  now  known  that  this  process  is  usually  accom- 
plished in  two  distinct  steps.  In  the  first  stage  the  ammonia  is  oxidized 
to  nitrous  acid.  This  is  done  by  the  nitrosobacteria.  These  nitrous  or 
nitrite  bacteria  were  called  by  Winogradski  nitrosomonas  and  nitrosococ- 
cus.     It  is  now  known  that  a  large  number  of  microorganisms  belong 


776  GENERAL  CONSIDERATIONS 

to  this  gi'oiip.  '^^riic  nitrites  exist  in  the  scjil  y)robably  as  salts  of  potas- 
sium and  sodium.  They  remain  as  the  lower  oxid  a  very  short  time 
and,  therefore,  never  aeeumulate,  and  are  never  found  in  ajiy  large 
amount  for  they  are  unstable  and  readily  oxidized  to  nitrates.  The 
special  nitric  or  nitrate  bacteria  (nitrobacter)  were  first  accurately 
described  by  Winogradski.  The  nitrates  are  stable  and  represent  the 
final  stage  of  the  mineralization  of  nitrogenous  matter.  In  certain  arid 
parts  of  the  world  large  deposits  of  nitrates  (KNO3,  saltpeter)  are 
found  as  the  result  of  the  nitrification  of  bird  excrement  (guano),  which 
is  rich  in  available  nitrogen.  These  collections,  however,  do  not  occur 
in  places  where  there  is  enough  rain  to  carry  away  the  readily  soluble 
nitrates. 

Ordinarily  the  nitrates  go  into  solution  in  the  ground  water  and  are 
either  taken  up  by  the  roots  of  plants  or  are  washed  away  in  tlie  ground 
water.  In  a  sanitary  analysis  of  water  taken  from  the  soil  the  presence 
of  nitrates  and  nitrites,  therefore,  has  a  special  significance.  If  nitrites 
are  found  in  soil  water  it  indicates  pollution  and  signifies  active  bacterial 
action  and  the  presence  of  organic  matter.  Nitrates  in  soil  water,  with- 
out nitrites,  are  an  index  of  past  pollution  (see  Water  Analysis). 

In  1886  Gayon  and  Dupetit  described  two  organisms,  B.  denitrificans 
a  and  j8,  capable  of  completely  reducing  nitrates.  Many  bacteria  have 
this  power  of  denitrification,  a  sort  of  reversible  process  by  which  nitrates 
are  reduced  to  ammonia.  This  is  characteristic  of  very  many  of  the 
well-known  microorganisms,  such  as  the  colon  group,  pyocyaneus,  sub- 
tilis,  and  other  soil  bacteria.  Denitrification,  however,  does  not  occur 
to  any  notable  extent  in  a  well-ventilated  soil. 

In  plant  metabolism  the  nitrates  are  used  to  build  up  new  protein. 
Certain  plants  get  some  of  their  nitrogen  through  the  bacterial  tubercles 
on  their  roots,  which  have  the  power  of  fixing  the  free  nitrogen  of  the 
air.  These  small  nodules  are  abundant  on  the  roots  of  various  legumi- 
nous plants  (peas,  clover,  etc.).  Pure  cultures  of  the  legume  or  nitrogen 
fixing  bacteria,  such  as  Bacillus  radicicola  of  Beyerinck,  may  be  obtained 
from  these  root  tubercles. 

It  should  be  noted  also  that  certain  bacteria  (azobacter)  have  the 
ability  to  fix  the  free  nitrogen  of  the  air  independently  of  plant  life  and 
may  grow  under  either  aerobic  or  anaerobic  conditions.  One  of  the 
first  known  of  this  group  was  an  anaerobe  described  by  Winogradski  in 
1895  and  named  by  him  Clostridium  pasteurianus. 

It  will  be  noted  that  in  the  nitrogen  cycle  all  the  essential  steps, 
from  proteolysis  to  mineralization  of  the  organic  matter,  nitrification, 
oxidation,  and  reduction,  as  well  as  the  fixation  of  free  nitrogen  from 
the  atmosphere,  are  all  the  result  of  bacterial  action.  Each  stage  of 
the  complex  process  is  specific,  in  the  sense  that  it  requires  a  particular 
species  or  group  of  bacteria  to  affect  the  result,  and  also  specific  in  the 


GENERAL  COXSTDERATTOJ^S  777 

sense  that  special  conditions  of  environment  are  necessary  for  its  action 
to  take  place. 

It  is  important  to  remember  that  practically  the  entire  cycle  takes 
place  upon  the  surface  and  in  the  upper  layers  of  the  soil.  A  few 
feet  below  the  surface  of  an  undisturbed  area  the  soil  contains  few  or 
no  bacteria.  Carcasses  buried  deep,  or  sewage  placed  too  far  below 
the  surface,  do  not  profit  by  the  nitrogen  cycle  in  its  entirety,  and  under 
such  circumstances  incomplete  nitrification  takes  place.  Nature's 
method  of  disposing  of  dead  wastes  is  thereby  defeated,  and  pollution 
of  the  soil  and  infection  of  the  ground  water  may  result. 

The  Carbon  Cycle. — Carbohydrates,  such  as  cellulose,  starch,  sugars, 
and  similar  constituents  of  vegetable  and  animal  matter,  are  fermented, 
with  the  formation  of  carbon  dioxid,  alcohol,  and  various  organic  acids. 
The  carbon  in  carbohydrates  passes  through  a  series  of  changes,  which 
may  be  regarded  as  the  carbon  cycle.  The  carbon  dioxid  resulting  from 
fermentation  unites  with  water  in  the  plant  life,  and  under  the  action 
of  chlorophyll  and  sunlight  is  again  synthetized  to  starch  and  sugars. 

The  fermentation  of  the  carbohydrates  is  also  due  to  the  action 
of  microorganisms.  In  a  mixture  containing  both  carbohydrates  and 
protein,  as  a  rule,  the  microorganisms  act  upon  the  carbohydrates  first. 
In  other  words,  the  putrefaction  of  protein  is  delayed  or  hindered  by  the 
presence  of  fermentable  carbohydrates.  For  this  reason  sewage  contain- 
ing wastes  from  breweries  always  presents  difficulties  at  disposal  plants. 

Fats  are  also  attacked  by  bacteria,  with  the  consequent  production 
of  acids.  The  hydrocarbons  are  broken  down  with  more  difficulty  than 
either  the  carbohydrates  or  protein.  An  excessive  amount  of  fat  in 
sewage  always  gives  trouble  on  a  filter.  For  instance,  the  drainage  from 
a  wool-scouring  mill  containing  lanolin  and  the  discharges  from  slaugh- 
ter houses  and  the  wastes  from  creameries,  laundries,  and  cheese  fac- 
tories containing  animal  fat  present  special  problems  in  sewage  dis- 
posal. 


CHAPTER  II 
THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

Bacteria  in  SoiL — Countless  millions  of  bacteria  occur  in  the  upper 
few  inches  of  the  soil.  The  enormous  overgrowth  of  bacteria  in  the 
upper  layers  of  the  soil  gives  it  the  sticky,  moist  feeling  which  rich 
soils  possess.  The  odor  of  the  soil,  such  as  that  which  is  particularly 
noticed  after  a  rainstorm,  is  due  in  large  part  to  Cladothrix  odorifera 
and  other  organisms  which  are  commonly  found  in  the  soil.  Few  bac- 
teria are  found  in  an  undisturbed  soil  below  a  depth  of  4  to  6  feet.  A 
sand  bed  used  for  filtering  sewage  shows  a  similar  vertical  distribution 
of  bacteria.  Below  six  feet  the  statement  is  made  that  the  soil  is  usually 
sterile.  This  is  not  strictly  true,  but  the  numbers  are  much  diminished 
and  bacterial  activity  has  practically  ceased.  As  a  rule,  living  bacteria 
are  not  obtained  from  samples  of  soil  obtained  10  to  13  feet  below  the 
surface,  except  in  soils  with  large  pores  or  crevices,  or  in  cases  where 
the  bacteria  have  been  carried  by  burrowing  animals.  It  is  exceedingly 
difficult  to  determine  the  number  of  bacteria  in  the  soil,  as  so  many  of 
them  are  anaerobes  and  vast  hordes  belong  to  the  nitrifying  groups, 
which  grow  only  upon  selective  media.  The  soil  is  also  the  home  of 
other  species,  requiring  special  conditions  for  growth  in  artificial  culture 
media. 

Of  the  ordinary  bacteria  that  grow  upon  the  usual  laboratory  media 
Houston  found  an  average  of  100,000  per  gram  in  an  uncultivated 
sandy  soil,  1,500,000  per  gram  in  a  garden  soil,  and  115,000,000  per 
gram  in  a  sewage  soil.  Peaty  soils  have  smaller  numbers.  The  actual 
numbers  must  be  vastly  greater,  for  many  microorganisms  in  the  soil 
do  not  grow  upon  the  common  media.  In  fact,  the  soil  is  the  home 
of  the  greatest  number  and  variety  of  bacteria  found  anywhere.  It  is 
the  bacteria  in  the  upper  layers  of  the  soil  that  make  it  resemble  a  living 
gland.  Each  particle  of  earth  is  coated  with  a  zoogleal  envelope.  The 
sand  and  mineral  particles  form  the  supporting  structures,  the  coat- 
ing of  bacteria  corresponds  to  the  glandular  epithelium,  and  the  in- 
terspaces between  the  particles  are  the  capillary  and  lymph  channels. 

Most  of  the  bacteria  in  the  soil  are  saprophytes.  The  microorgan- 
isms pathogenic  for  man  do  not  find  conditions  favorable  for  growth 
and  development  in  the  soil.  For  the  most  part  the  temperature  is  too 
low;  further,  they  are  crowded  out  by  the  overgrowth  of  the  saprophytes. 
Koch   has   demonstrated   that   anthrax   and   other   pathogenic   bacteria 

778 


THE  SOIL  AND  ITS  RELATION  TO  DISEASE  779 

may  be  grown  in  sterile  soil,  but  cannot  be  grown  in  unsterilized  soil, 
that  is,  in  living  soil.  They  die  in  the  struggle  for  existence.  Experi- 
ments have  shown  that  the  soil  of  graveyards  contains  no  more  bacteria 
than  the  corresponding  soil  in  the  same  locality,  and  is  noticeable  by 
the  absence  of  pathogenic  microorganisms.  The  soil  often  contains  the 
bacteria  (or  their  spores)  of  certain  wound  infections,  such  as  malig- 
nant edema,  anthrax,  B.  aerogenes  capsulatus,  and  tetanus.  The  rela- 
tion of  the  soil  to  typhoid,  cholera,  dysentery,  hookworm  disease,  Cochin- 
China  diarrhea,  and  other  infections  will  be  discussed  presently. 

The  function  of  the  bacteria  in  the  soil  may  best  be  understood  by 
studying  the  fate  of  organic  matter  polluting  the  soil  and  the  processes 
which  accomplish  its  purification  (see  Nitrogen  Cycle,  page  773). 

Pollution  of  the  Soil. — The  soil  is  capable  of  disposing  of  great  quan- 
tities of  organic  matter.  However,  if  it  is  overburdened  it  remains  pol- 
luted and  may  endanger  health  through  contamination  of  the  drink- 
ing water  and  in  other  ways.  It  is  not  only  the  amount  but  the  kind 
of  pollution,  and  also  the  manner  of  its  disposal,  that  plays  a  very 
important  part.  It  must  first  of  all  be  remembered  that  the  purify- 
ing action  of  the  soil  is  largely  dependent  upon  bacteria,  and  that  this 
action  takes  place  almost  solely  in  the  upper  layers.  If  carcasses  are 
buried  deeply,  or  if  sewage  is  allowed  to  enter  the  soil  at  several  or 
more  feet  below  the  surface,  the  process  of  purification  is  long  delayed 
or  checked.  A  leaky  cesspool  or  broken  drain  which  discharges  its 
contents  into  the  soil  at  a  depth  of  5  feet  or  more  may  seriously  pol- 
lute the  ground  water,  whereas  the  same  material  placed  upon  or  just 
beneath  the  surface  may  be  entirely  mineralized  and  all  infection  de- 
stroyed before  it  reaches  the  depth  of  5  feet.  Vegetable  matter  in  a 
water-logged  soil  undergoes  a  partial  and  unusual  decomposition  into 
muck  or  peat.  Trees  buried  deeply,  where  bacterial  action  is  practically 
absent,  remain  for  many  hundreds  of  years  practically  unchanged. 
Many  factors  retard  the  purifying  action  of  the  soil.  Among  these  the 
temperature  and  moisture  and  absence  of  oxygen  predominate. 

When  organic  matter  falls  upon  the  soil  it  is  consumed  and  di- 
gested by  the  hungry  earth.  Without  this  property  the  surface  of  the 
earth  would  long  ago  have  become  clogged  with  vegetable  and  animal 
matter.  Albuminous  substances  are  dissolved  by  the  action  of  the  pro- 
teolytic bacteria,  and  converted  into  simpler  chemical  compounds.  The 
intermediate  products  of  protein  putrefaction  are  exceedingly  complex. 
For  our  present  purposes  it  is  sufficient  to  know  that  ultimately  the 
nitrogen  is  largely  converted  into  ammonia  and  the  carbon  into  carbon 
dioxid.  The  ammonia  is  then  oxidized  by  the  action  of  nitrifying 
bacteria  to  nitrites,  and  the  nitrites  again  oxidized  to  nitrates.  The 
nitrates  are  the  final  products  of  the  mineralization  of  organic  matter. 
Most  of  the  nitrates  pass  into  solution  and  are  carried  down  into  the 


780  THE  SOU.  A^D  ITS  IIELATIOX  TO  DISEASE 

deeper  layers  of  the  soil  or  sub-soil;  some  of  it  is  taken  up  through  the 
roots  of  plants.  The  carbon  dioxid  passes  off  into  the  air  as  a  gas, 
remains  in  the  soil  moisture  in  solution,  or  is  converted  into  carbonates. 

Pathogenic  bacteria  that  may  be  thrown  upon  the  soil  in  feces  or 
otherwise  are  usually  detained  in  the  upper  layers  and  finally  destroyed 
there.  Under  ordinary  conditions  pathogenic  microorganisms  are 
caught  in  the  upper  layers  of  the  soil,  just  as  they  are  caught  upon 
the  "schmutzdecke"  of  a  slow  sand  filter.  The  soil  does  not  act  simply 
as  a  mechanical  trap.  The  bacteria  are  detained  and  destroyed  by  a 
combination  of  physical,  chemical,  and  vital  processes  taking  place  in 
the  upper  layers  of  the  soil. 

All  polluted  soils  are  not  equally  dangerous.  Soils  polluted  with 
human  feces  and  urine  present  the  greatest  hazard  to  man.  The  special 
menace  of  soils  polluted  with  human  excreta  is  from  typhoid  bacilli, 
hookworms,  and  other  infections  discharged  in  the  feces  or  urine.  Hook- 
worm infection  is  usually  contracted  directly  from  soils  polluted  with 
human  feces,  and  the  eradication  of  hookworm  disease  depends  pri- 
marily upon  preventing  pollution  of  the  soil.  The  danger  in  the  case 
of  typhoid,  dysentery,  cholera,  and  other  bacterial  infections  is  usually 
indirect  through  infection  of  drinking  water  or  occasionally  through 
flies  or  other  mechanical  means  of  transference.  A  soil  polluted  with 
typhoid  may  endanger  either  the  surface  water  or  the  ground  water, 
particularly  in  limestone  formations.  Pathogenic  microorganisms  in  a 
polluted  soil  may  also  find  their  way  back  to  man  upon  vegetables. 
Tapeworms  and  other  intestinal  parasites  pass  part  of  their  life  cycle 
on  or  in  the  soil,  and  may  infect  man  directly  or  indirectly  in  various 
ways.  The  question  of  soil  pollution  and  the  particular  ways  in  which 
it  is  related  to  health  have  been  discussed  separately  under  each  disease 
concerned. 

Dirt. — The  soil  is  often  spoken  of  as  dirt.  The  soil  in  the  field  is 
"earth,''  but  in. the  parlor  or  on  our  hands  it  becomes  dirt;  that  is, 
matter  out  of  place.  The  word  "dirt"  is  from  the  old  Saxon  "drit," 
meaning  excrement.  Dirt  in  the  ordinary  sense  becomes  a  potential 
danger,  especially  when  containing  human  excretions  or  soil  bacteria 
associated  with  wound  infections. 

To  the  sanitarian  dirt  includes  rubbish,  manure,  and  organic  wastes 
of  all  kinds.  It  may  be  the  vehicle,  but  not  the  source,  of  infection. 
It  breeds  and  harbors  flies,  fleas,  lice,  rats,  mice,  and  vermin  of  all 
sorts  that  act  as  intermediate  hosts  or  carriers  of  infection.  While  dirt 
cannot  originate  typhoid  fever  or  other  infections,  it  favors  conditions 
which  encourage  the  spread  of  such  diseases.  Rubbish  in  vacant  lots, 
in  backyards,  in  alleys,  in  cellars,  garrets,  and  other  places  may  be 
taken  as  an  index  of  the  failure  to  appreciate  the  modern  teachings  of 
hygiene  and  sanitation.     It  was  once  the  chief  duty,  and  still  an  im- 


THE  SOIL  AXD  ITS  RELATION  TO  DISEASE  781 

portant  one,  of  the  health  officer  to  insist  upon  cleanliness  of  premises 
and  surroundings,  both  in  country  and  city. 

Cleanliness. — Cleanliness  is  the  heart  and  soul  of  sanitation.  We 
are  inclined  to  place  it  even  before  godliness,  for  cleanliness  of  body, 
cleanliness  of  mind  and  soul,  and  cleanliness  of  our  surroundings  are 
essential  to  a  full  appreciation  of  the  spiritual  virtues.  Our  conception 
of  cleanliness  has  greatly  changed  with  our  advance  in  knowledge  of  the 
kinds  of  dirt,  the  degrees  of  dirtiness,  and  the  nature  of  these  dangers. 
We  can  no  longer  be  satisfied  with  physical  or  esthetic  cleanliness,  but 
must  insist  upon  biological  cleanliness.  A  tetanus  spore  upon  the  shin- 
ing blade  of  a  surgeon's  knife  makes  that  instrument  filthy,  whereas 
many  such  spores  on  the  skin  of  a  chicken  may  be  harmless  when  in- 
gested. We  cannot  see  the  infection  upon  the  common  drinking  cup, 
upon  the  roller  towel,  upon  the  point  of  a  pencil  that  has  just  been 
moistened  with  saliva,  or  in  water,  milk,  or  food,  although  we  well 
know  the  danger  of  such  invisible  "dirt"  that  these  objects  may  harbor. 

It  requires  a  bacteriologist  to  tell  the  difference  between  clean  dirt 
and  dirty  dirt.  We  lack  a  sixth  sense,  or  microscopic  eye,  to  see  and 
distinguish  the  harmful  germs.  We,  therefore,  must  practice  scrupu- 
lous cleanliness  and  educate  the  people  to  the  biological  meaning  of 
this  term.  Long  experience  has  taught  the  lesson  that  cleanliness  offers 
a  protection  against  disease;  that  clean  surroundings  are  apt  to  be  free 
of  infection ;  and  that  clean  food  is  apt  to  be  safe  food. 

Cleanliness  of  person  and  environment  results  in  the  diminution  of 
the  number  and  perhaps  the  virulence  of  many  pathogenic  microorgan- 
isms, such  as  streptococci  and  staphylococci.  Cleanliness  of  the  type 
that  approaches  asepsis  would  prevent  much  sickness  and  save  many 
lives  through  diminishing  the  risk  of  infections.  Hill  believes  that  the 
mildness  of  modern  infectious  diseases  is  due  to  the  lessened  virulence, 
smaller  stock,  and  reduced  distribution  of  the  streptococci  and  staphy- 
lococci formerly  bred  in  hospitals  and  in  wounds  promiscuously.  The 
public  health  officer  should,  therefore,  campaign  for  medical  asepsis  as 
the  surgeon  does  for  surgical  asepsis. 

Many  houses,  especially  in  poorer  sections  of  cities,  lack  proper  facili- 
ties for  laundry  work.  Public  laundries,  such  as  are  provided  in  many 
European  countries,  ^would  materially  help  in  the  campaign  for  general 
cleanliness. 

At  one  time  the  theory  of  the  filth  diseases  reached  the  dignity  of 
a  special  name — the  pythogenic  theory,  first  propounded  by  Murchin- 
son  in  1858.^     Typhoid  fever  was  long  regarded  as  the  type  of  a  filth 

^  "I  shall  bring  forward  what  I  consider  positive  proof  that  this  fever 
(typhoid)  is  produced  by  emanations  from  decaying  organic  matter;  and  I 
would  therefore  suggest  for  it  the  appellation  of  'pythogenic  fever!' "  Mur- 
chison:  "Contributions  to  the  etiology  of  Continued  Fever,"  p.  219.  "Medico- 
Chirurgical  Transactions,"  London,  1858,  Vol.  XLI,  p.  221. 


1S2  THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

disease,  and,  while  we  are  now  dropping  that  term,  we  should  not 
forget  that  typhoid  fever  is  really  a  filthy  disease,  for  each  ease  means 
that  a  short  circuit  has  been  established  between  the  discharges  from  one 
person  and  the  mouth  of  another. 

The  Influence  of  the  Soil  upon  Health. — The  soil  was  formerly 
accused  of  being  one  of  the  largest  and  most  important  factors  in  the 
spread  of  the  communicable  diseases.  It  was  once  regarded  as  the 
cause,  if  not  the  nesting  place,  of  infections  of  all  kinds;  tuberculo- 
sis, malaria,  typhoid  fever,  plague,  yellow  fever,  cholera,  dysentery,  and 
many  other  diseases  were  directly  associated  with  the  soil.  We  now- 
know  that  comparatively  few  of  the  microorganisms  pathogenic  for 
man  live  in  the  soil,  and  practically  none  of  them  grow  and  multiply 
there. 

The  soil  contains  a  number  of  bacteria  that  may  be  serious  when 
introduced  into  wounds,  as  tetanus,  malignant  edema,  anthrax,  B.  aero- 
genes  capsulatus ;  ofttimes  organisms  belonging  to  the  hemorrhagic  sep- 
ticemic group;  sometimes  staphylococci  and  streptococci. 

A  soil  polluted  with  human  excrement  presents  the  possibility  of 
danger  of  intestinal  infections  of  all  kinds.  Thus,  bacterial  infections, 
such  as  typhoid,  cholera,  and  dysentery,  or  protozoal  infections,  such 
as  amebic  dysentery,  or  the  higher  worms,  such  as  hookworms,  may  all 
more  or  less  be  associated  with  polluted  soils. 

Soils  containing  much  organic  matter  and  presenting  other  favor- 
able conditions  afford  resting  and  nesting  places  for  a  number  of  in- 
sects, such  as  flies,  ticks,  eic,  which  may  carry  infections. 

Vegetables  grown  in  polluted  soils  may  transfer  bacteria,  protozoa, 
or  the  eggs  of  worms  in  a  mechanical  way  from  the  ground  to  the 
mouth.  This  applies  particularly  to  vegetables  eaten  raw,  such  as 
radishes,  lettuce,  etc. 

Practically  all  the  water  used  for  drinking  and  other  purposes  has 
either  rested  upon  the  soil  or  has  percolated  through  it  into  the  ground. 
The  soil  materially  affects  the  character  of  the  water.  In  this  way  the 
soil  indirectly  influences  health  variously  and  sometimes  seriously.  The 
relation  of  water  to  health  is  a  subject  in  itself,  and  is  discussed  in 
a  separate  chapter. 

The  physical  conditions  of  the  soil  which  have  special  reference  to 
health  are  those  which  influence  the  temperature  and  moisture  of  hu- 
man habitations.  Persons  working  about  cold  and  damp  soils  are  sub- 
ject to  rheumatic,  neuralgic,  and  respiratory  affections. 

Diseases  Associated  with  the  Soil. — Tetanus. — Spores  of  the  tetanus 
bacillus  commonly  occur  in  the  soil  of  inhabited  regions.  They  have 
been  found  not  only  in  the  superficial  layers,  but  sometimes  at  a  depth 
of  several  feet.  The  normal  habitat  and  the  great  reservoir  of  tetan-us 
are  the  intestines  of  the  herbivora.     It  may  also  be  found  in  the  intes- 


THE  SOIL  AND  ITS  RELATION  TO  DISEASE  783 

tinal  contents  of  man  and  other  animals.  Certain  savages  in  the  New 
Hebrides  used  to  smear  their  arrow  heads  with  dirt  from  crab  holes 
in  the  swamp,  which  they  knew  by  experience  to  be  poisonous.  We 
now  know  that  this  material  contained  tetanus  spores. 

Tetanus  increases  as  we  approach  the  tropics,  where  puerperal  tet- 
anus and  tetanus  of  the  newborn  are  relatively  frequent.  Tetanus  spcres 
are  much  more  abundant  in  certain  localities  than  others.  For  ex- 
ample, certain  parts  of  Long  Island  and  New  Jersey  have  become  not- 
able for  the  number  of  cases  of  tetanus  caused  by  small  wounds. 

The  tetanus  bacillus  probably  does  not  grow  and  multiply  in  the 
soil.  It  cannot  there  find  the  necessary  anaerobic  conditions,  tempera- 
ture, and  other  factors  necessary  for  multiplication.  The  resistance 
of  the  spores  accounts  for  the  persistence  of  the  infection. 

The  prevention  of  tetanus  has  been  discussed  on  page  80. 

Anthrax. — Like  tetanus,  anthrax  does  not  grow  in  the  soil  under 
natural  conditions.  Its  persistence  is  accounted  for  by  its  resistant 
endospore.  Anthrax  spores  have  been  found  in  pastures  where  infected 
animals  have  been  confined. 

The  anthrax  bacillus  requires  oxygen  in  order  to  sporulate;  the 
spores,  therefore,  do  not  form  in  the  blood,  and  it  is  very  important 
not  to  open  the  carcass  of  a  sheep  or  cow  dead  of  this  disease  before 
it  is  buried.  The  classic  researches  of  Pasteur  on  anthrax  should  be 
studied  in  this  connection.  Pasteur  examined  the  field  where  animals 
dead  of  anthrax  had  been  buried  twelve  years  previously.  He  found 
the  specific  bacillus  in  the  soil  and  demonstrated  its  virulence  by 
inoculations  into  guinea-pigs.  Pasteur  thought  that  the  spores  were 
brought  to  the  surface  of  the  soil  by  earthworms,  and  proved  the  pos- 
sibility of  this  by  sowing  virulent  cultures  in  soil  and  recovering  the 
bacillus  from  worm  casts.  It  seems,  however,  in  the  light  of  subse- 
quent investigations  that  the  danger  from  this  source  is  negligible,  so 
that  anthrax,  with  a  few  exceptions,  can  hardly  be  called  a  soil  in- 
fection. This  is  the  case  at  least  with  man,  for  there  is  no  instance 
on  record  in  which  human  anthrax  has  been  contracted  from  contact 
with  the  soil. 

Malignant  Edema. — The  bacillus  of  malignant  edema  is  found  in 
the  superficial  layers  of  the  soil.  It  is  very  widely  distributed.  This 
organism  is  also  found  in  putrefying  substances,  in  foul  water,  and  in 
the  intestinal  tract  of  various  animals.  In  1877  Pasteur  first  recog- 
nized an  organism  belonging  to  this  group  by  injecting  animals  with 
putrefying  liquids.  He  called  the  organism  the  vibrion  septique,  recog- 
nized its  anaerobic  nature,  but  did  not  obtain  it  in  pure  culture.  Koch 
and  Gaffky  in  1881  studied  it  carefully  and  renamed  it  the  bacillus  of 
malignant  edema.  The  bacillus  has  lateral  flagella,  an  oval  spore,  and 
is  a  strict  anaerobe.     It  is  very  pathogenic  for  almost  all  animals,  caus- 


784  THE  SOIL  AND  ITS  EELATION  TO  DISEASE 

iiig  extensive  hemorrhagic  edema  without  the  production  of  gas,  which 
distinguishes  it  from  the  gas  bacillus  of  Welch.  Wound  infections  with 
malignant  edema  occur,  especially  with  deep  punctured  or  lacerated 
wounds,  which  favor  anaerobic  growth.  Before  the  days  of  antisepsis 
this  complication  was  frequent,  especially  during  wars. 

Bacillus  Welchii,  also  known  as  Welch's  Gas  Bacillus  and  B. 
aerogenes  cafsulatus. — This  organism  is  a  member  of  a  populous  and 
widely  distributed  species  of  bacteria,  which  have  in  common  the  ability 
to  ferment  sugars  with  the  production  of  butyric  acid.  B.  Welchii  is  a 
large  rod,  gram-positive,  and  usually  grows  singly  or  in  pairs.  Spore 
formation  is  inconstant  and  occurs  only  in  alkaline  media,  never  in  pure 
cultures  in  media  containing  a  fermentable  sugar  or  free  acid.  It  causes 
stormy  fermentation  of  milk ;  that  is,  the  milk  is  quickly  coagulated  and 
gas  formation  is  so  abundant  as  to  break  up  the  curd  and  even  to  force 
parts  of  it  above  the  cream  ring.  A  rabbit  injected  intravenously  with 
this  organism,  killed  within  two  or  three  minutes  and  incubated,  pre- 
sents in  twenty-four  hours  a  body  enormously  distended  with  gas  which 
will  burn  with  a  pale  blue  flame.^ 

This  bacillus  is  found  in  the  intestinal  canal  of  man  and  animals, 
in  soil  and  dust  which  distributes  it  widely.  When  introduced  in  wounds 
it  causes  a  serious  infection  with  the  production  of  gas.  In  the  present 
war  many  wounds  contaminated  with  the  soil  of  the  trenches  have  been 
complicated  with  this  infection. 

Many  other  microorganisms,  especially  those  belonging  to  the  hemor- 
rhagic septicemic  group,  occur  in  the  soil  and  occasionally  complicate 
wounds. 

Typhoid  Fever. — There  is  a  widespread  belief,  even  among  sani- 
tarians, that  this  disease  is  frequently  connected  with  soil  pollution. 
This  belief  was  given  scientific  confirmation  by  Pettenkofer,  who  pro- 
pounded the  theory  that  the  poison,  whatever  it  may  be,  is  introduced 
into  the  soil  where,  under  proper  conditions  of  organic  filth,  tempera- 
ture, moisture,  etc.,  a  special  fermentation  takes  place.  Pettenkofer 
believed  that  the  gases  or  effluvia  thus  produced  rise,  and  in  some  way 
were  capable  of  provoking  disease.  Pettenkofer's  views  of  typhoid  in 
relation  to  the  height  of  the  ground  water  have  already  been  mentioned. 

Typhoid  bacilli  frequently  find  their  way  upon  and  into  the  soil 
along  with  human  excreta.  Multiplication,  however,  rarely  takes  place 
there.  As  a  rule,  the  typhoid  bacillus  scarcely  liVes  a  month,  possibly 
two  or  three  months,  in  the  soil.  When  frozen  they  may  live  and  re- 
main virulent  for  several  months,  as  in  the  case  of  the  Plymouth  epi- 
sode and  the  New  Haven  epidemic.     While  typhoid  fever  in  cities  and 

^  "Studies  in  B.  Welchii,  with  Special  Reference  to  Classification  and  to  Its 
Relation  to  Diarrhea."  J.  P.  Simonds,  Monographs  of  the  Rockefeller  Institute, 
No.  5,  September  27,  1915. 


THE  SOIL  AND  ITS  RELATION  TO  DISEASE  785 

towns  has  no  evident  direct  relation  to  soil  pollution,  it  is  pos- 
sible to  conceive  an  indirect  relation  in  many  cases,  especially  in  camps 
and  in  rural  districts. 

There  are  numerous  ways  by  which  typhoid  bacilli  may  be  returned 
from  the  soil  to  the  mouth  of  a  susceptible  person.  It  is  possible,  though 
not  likely,  for  this  to  occur  directly.  So  far  as  typhoid  is  concerned, 
perhaps  the  greatest  danger  from  a  polluted  soil  consists  in  infection 
of  the  drinking  water.  The  ways  in  which  this  may  occur  are  dis- 
cussed in  the  chapter  on  water.  The  transfer  of  typhoid  bacilli  from 
the  soil  to  the  mouth  may  also  occur  mechanically  by  means  of  flies, 
dust,  and  dirt.  Vegetables  grown  in  a  polluted  soil  may  carry  typhoid 
bacilli  to  the  very  tips  of  their  leaves. 

The  pollution  of  soil  with  human  feces  is  always  a  danger  and 
should  be  prevented.  The  worst  offense  in  this  particular  occurs  in 
country  districts,  where  the  potential  danger  is  greater  than  in  the  city. 

GoiTEE. — The  soil  and  its  underlying  rocky  strata  have  long  been 
associated  with  endemic  goiter,  in  some  indirect  wa}^  either  through 
chemical  constituents  or  bacterial  contamination  of  drinking  water 
coming  in  contact  with  certain  geological  formations.  Goiter  is  most 
prevalent  in  the  regions  underlaid  by  the  Silurian,  Carboniferous,  and 
Permian  systems;  while  those  over  the  eruptive  or  crystalline  rocks  of 
the  Archean  group,  the  sediment  of  Jurassic,  Cretaceous,  and  post  ter- 
tiary seas,  as  well  as  all  fresh-water  deposits,  are  comparatively  free 
from  the  affection. 

In  some  cases  goiter  does  appear  in  localities  over  the  second  group, 
but  in  these  places  the  underlying  strata  are  thin  and  ground  water 
penetrates  to  lower  groups.  It  is  observed  also  that  the  influence  of  the 
first  group  is  weakened  or  lost  by  superimpositions  of  the  fresh-water 
strata. 

Baillarger,  in  a  masterly  review  of  this  subject  in  1873,  concluded 
that  "it  had  not  been  shown  that  goiter  prevailed  exclusively  on  any 
particular  soil,  but  that  it  seemed  to  prove  that  the  endemic  is  extremely 
common  on  the  dolomite  formations  and  rare  on  others." 

The  relation  of  goitre  to  the  soil  is  doubtful.  For  further  discussion 
on  this  subject  see  page  916. 

Cholera. — There  is  every  reason  to  believe  that  the  cholera  vibrio 
dies  quickly  when  deposited  upon  or  in  the  soil  under  natural  condi- 
tions. The  cholera  vibrio  may  be  transferred  from  the  soil  to  the  mouth 
in  the  ways  mentioned  above  in  the  case  of  typhoid.  Formerly  cholera 
was  believed  to  be  associated  with  polluted  soils,  but  it  now  appears  that 
the  disease  is  rarely  contracted  from  the  soil,  and  that  the  physical  and 
chemical  conditions  of  the  ground  play  little,  if  any,  role  in  the  epi- 
demiology of  this  disease. 

Tuberculosis  and  Other  Diseases. — In  1863  Dr.  H.  I.  Bowditch 


786  THE  SOIL  AND  ITS  KELA'I'ION  'I'O  DISKASI*] 

formulated  the  law  of  soil  moisture  from  studies  which  seemed  to  indi- 
cate that  tuberculosis  was  more  common  in  Massachusetts  over  moist 
soils  than  dry  ones.  If  there  is  any  connection  between  tuberculosis 
and  the  soil,  the  relation  must  be  indirect.  Exposure  to  cold  and  damp 
depresses  vitality  and  lowers  resistance  to  tuberculosis.  It  does  not 
necessarily  follow  that  habitations  or  workshops  are  cold  and  damp 
because  the  ground  on  which  these  houses  are  built  is  wet  and  cold. 

The  soil  was  formerly  accused  of  being  responsible  for  plague, 
malaria,  yellow  fever,  and  a  long  list  of  other  diseases.  The  impor- 
tance of  the  soil  with  reference  to  the  communicable  diseases  diminishes 
with  our  increase  in  knowledge.  The  number  of  infections  directly 
associated  with  the  ground  are  very  few,  and  the  indirect  influences 
are  less  than  formerly  supposed. 

Apart  from  the  one  real  danger,  viz.,  soil  pollution  with  human  ex- 
crement, the  sanitarian  is  now  inclined  to  belittle  the  influence  of  the 
soil  upon  health. 

Dampness  and  cold  may  favor  rheumatic  and  neuralgic  conditions, 
and  also  predispose  to  respiratory  infections.  In  this  way  association 
with  a  cold,  damp  soil  may  be  prejudicial  to  health.  Clay  soils  are 
apt  to  be  damp;  sand  and  gravel  soils  are  readily  drained  and  may 
be  kept  dry  by  means  of  simple  devices.  Such  soils,  therefore,  make 
the  best  building  sites  for  habitations.  As  a  rule,  the  foundation  of  a 
house  should  be  at  least  two  or  three  feet  above  the  level  of  the  ground 
water. 

The  soil  greatly  influences  the  character  of  the  water  which  rests 
upon  it  and  which  passes  through  it.  This  will  be  discussed  in  the  sec- 
tion on  water. 

HooKW^ORM  Disease. — Hookworm  disease  is  closely  associated  with 
the  soil.  It  may  fairly  be  considered ,  an  infection  the  result  of  soil 
pollution.  It  occurs  especially  in  moist  sandy  soils  rather  than  on 
clay  or  rocky  soils.  This  is  due  to  the  fact  that  hookworm  eggs,  when 
deposited  in  fecal  matter,  soon  dry  up  and  die  upon  hard  rocky  or 
clay  surfaces,  whereas  they  find  favorable  conditions  for  development 
upon  moist  sand  or  loam.  Under  these  conditions  the  larvae  develop 
as  far  as  the  second  ecdysis,  which  have  the  power  of  penetrating  the 
skin  (see  page  139), 

Other  Animal  Parasites. — In  a  somewhat  similar  sense  many  oi 
the  animal  parasites  of  man  are  deposited  on  the  soil  and  reinfect  man 
during  one  of  the  stages  of  their  cycle  of  development.  Most  of  the 
intestinal  parasites  of  man  are  deposited  on  the  soil,  and,  after  a  vary- 
ing journey,  sometimes  through  an  intermediate  host,  again  find  lodg- 
ment in  man.  In  the  case  of  trichina,  for  instance,  man  pollutes  the 
soil  with  feces  containing  the  eggs.  Hogs  devour  this  infection  and 
return  the  disease  to  man.    In  a  somewhat  similar  way  the  tapeworms 


THE  SOIL  AND  ITS  EELATION  TO  DISEASE  787 

of  cattle  and  also  some  ameba  and  flagellates  pass  part  of  their  life 
history  upon  the  soil. 

The  Ascaris  lumbricoides  and  the  Trichuris  trichiura,  two  very  com- 
mon worms  inhabiting  the  intestinal  tract  of  man,  have  thick-shelled 
eggs  and  must  rest  in  the  soil  about  a  month  before  they  are  infective. 
It  requires  about  a  month  for  the  embryo  to  develop.  If  fresh  eggs- 
of  these  two  worms  are  ingested,  they  pass  through  the  intestinal  tract 
without  hatching. 

Ldst  of  animal  parasites  of  man  which  may  he  spread  by  soil  pollution 


Direct:  without  intermediate 
host. 


Indirect:  with  intermediate 
host. 


Requires  further  study.     Probably 
I  or  II  as  marked. 


PROTOZOA 


Loschia       [Entamoeba] 
"         tetragena 
"         hystolytica 
"         buccalis 
Paramoeba  hominis 
Chlamydophrys  enchelya 
Cercomonas  vaginalis 
Prowazekia    asiatica 
Tetramitus  mesnili 
Trichomonas  vaginalis 

"  hominis 

Eimeria  hominis 
Isospora  bigemina 
Balantidium  coli 
Lamblia  intestinalis 


coli 


Loschia    [Entamoeba]    trop: 

ealis. 
Loschia  undulans 

"         phagocytoides 
"         minuta 
"         nipponica 
"         brasiliensis 
"         hartmanni 
"         biltschlii 
Cercomonas  hominis 
Prowazekia  cruzi 

"  urinaria 

"  Weinberg! 

Monas  pyophila 

"       leus 
Heteromita  zeylanica 
Trichomonas   dysenteriae 
"  pulmonalis 

Ehinosporidium  seeberi 
Balantidium  minutum 
Nictotherus  faba 

"  giganteus 

"  africanus 


TREMATODA 


Fasciola  hepatica 
Opisthorchis    felineus 
Clonorchis  endemicus 
Paragonimus     wester- 

mani 
Schistosoma      japoni- 

cum 


Fasciola  gigantica  il 

Watsonius  watsoni  ii 

Gastrodiscus   hominis  il 

Fasciolopsis  buski  n 

"             fiilleborni  II 

Echinostoma  ilocanum  II 

* '             malayanum  II 

Opisthorchis   noverca  il 

Clonorchis   sinensis  ii 

Heterophyes   heterophyes  n 

Dicrocoelium  lanceatum  il 
Schistosoma  haematobium  ii 

"             mansoni  n 


788  THE  SOIL  AND  ITS  RELATION  TO  DISEASE 

List  of  animal  parasites  of  man — continu  -d 


Direct:  without  intermediate 
host. 


Indirect:  with  intermediate  Requires   further   study.    Probably 
host.  I  or  II  as  marked. 


CESTODA 


D  i  b  o  t  h  r  ioce 
latua 

phalus 

Dibothriocephalus  parvus 

II 

D  i  b  o  t  h  r  ioce 

phalus 

cordatus 
Dipylidium  caninum 
Hymenole    pis    d  i  ni- 

inuta 
Hymenolepia       lance- 

olata 

Diplogonoporus   grandis 
"                 brauni 

Hymenolepia   nana 

Davinea  madagascariensis 

II 
II 

II 

II 

Taenia  solium 

"         asiatica 

II 

"       saginata 

Taenia  africana 
"       hominis 
"       philippina 
"       confusa 
"       bremneri 

Braunia  jayensis 

II 
II 
II 
II 
II 
II 

NEMATODA 


Leptodera  pellio 
Strongyloides  stercoralis 
Gnathostoma  spinigerum 
Ascaris   lumbricoides 
Toxascaris  canis 
Belascaris    mystax 
Lagocheilascaris   minor 
Oxyuris   vermicularis 
Haemonchus   contortus 
Ancylostoma   duodenale 
Necator  americanus 
Trichuris  trichiura 


Dracunculus  medinen- 

sis 


Physaloptera   caucasia  i 

"  mordens  i 

Ascaris  maritima  i 

"         texana  i 

Tridontophorus  diminutus  i 
Oesophagustomum     apiosto- 

mum  I 

Oesophagustomum    stephan- 

ostomum  i 

Metastrongylus  apri  i 

Nematodirus  gibsoni  l 

Trichostrongylus   c  o  1  u  b  ri- 

formis  i 

Trichostrongylus        probulu- 

rus  I 

Trichostrongylus  vitrinus  i 
Dioctophyme  renale  ii 


ACANTHOCEPHALA 


Gigantorhynchus  gi- 
gas 

Gigantorhynchus  mo- 
niliformis 


The  above  table  ^  (pp.  787-788)  gives  a  list  of  animal  parasites  having 
a  relation  to  the  soil  during  some  part  of  their  life  history,  and  may, 
therefore,  be  more  or  less  associated  with  soil  pollution.  It  will  be  no- 
ticed that  for  the  most  part  Protozoa  and  Nematoda  are  contracted  di- 
rectly, whereas  Trematoda,  Cestoda  and  Acanthocephala  are  contracted 
indirectly  and  through  an  intermediate  host. 

^This  table  for  the  first  edition  was  prepared  by  Ch.  Wardell  Stiles;   cor- 
rected and   brought  to  date  bv  Dr.  J.  P.  Bill. 


SECTION  VI 
WATER 

CHAPTEE  I 

GENEEAL  CONSIDEEATIONS 

"The  greatest  influence  on  health  is  exerted  by  those  things  which  we 
most  freely  and  frequently  require  for  our  existence,  and  this  is  especially 
true  of  water  and  air"  (Aristotle). 

While  water  is  not  technically  classed  as  a  food,  it  is  an  essential 
article  of  diet.  In  nature  water  comes  in  contact  with  many  surfaces 
and  substances  and,  therefore,  is  particularly  liable  to  contain  impuri- 
ties, especially  as  it  is  the  most  universal  solvent  known.  Water  is 
also  a  frequent  medium  for  the  transmission  of  infection. 

From  the  remotest  antiquity  the  highest  value  has  been  placed 
upon  an  abundant  and  pure  water  supply.  Centers  of  population  sprang 
up  in  ancient  times  around  those  points  where  it  was  most  readily 
available,  and  great  expenditures  of  labor  and  treasure  were  made  to 
carry  it  to  places  where  it  was  not  naturally  plentiful.^ 

Water  is  a  prime  necessity  of  life — not  only  as  an  article  of  diet, 
but  also  for  the  proper  cleanliness  of  person,  clothing,  and  things. 

It  is  interesting  to  note  that  the  number  of  towns  in  this  country 
before  1800  having  a  public  water  supply  was  only  16,  supplying  about 
2.8  per  cent,  of  the  existing  population  at  that  time.  In  1850  there 
were  only  83  public  water  works,  supplying  about  10.6  per  cent,  of  the 
census  population.  In  1897  the  total  number  was  3,196,  supplying 
about  41.6  per  cent,  of  the  population.  Since  then  the  number  has 
greatly  increased,  but  exact  information  is  not  available.^ 

COMPOSITION 

At  the  close  of  the  eighteenth  century  water  was  regarded  as  an 
elementary  substance.     In   1781   Cavendish  discovered  that,  when  an 

^Thje  date  of  construction  of  the  Appian  aqueduct  carrying  water  to  Rome 
is  placed  at  312  B.  C.  Eighteen  other  aqueducts  were  constructed  at  various 
times  until  226  A.  D.  The  one  commenced  by  Emperor  Caius  and  completed  by 
Claudius,   according  to  Pliny,  cost  350,000,000  sesterces,  or  about  $12,700,000. 

''Baker,  M.  N. :   "Manual  of  American  Water  Works,"   1891  and  1897. 

789 


790  GENERAL  CONSIDERATIONS 

electric  spark  is  passed  through  a  mixture  of  2  parts  of  hydrogen  to 
1   part   of  oxygen,   these  gases   combine   to    form   water.      Sinf;o   then 
water  has  been  made  synthetically,  and  separated  analytically  into  its 
component  constituents  by  various  methods. 
The  composition  of  pure  water  (HgO)  is: 


Oxygen .  . . 
Hydrogen . 


By  Volume 

By  Weight 

1  part 

8  parts 

2  parts 

1  part 

Pure  water  is  a  chemical  curiosity;  it  does  not  exist  in  nature. 
All  water  in  nature  contains  impurities,  in  solution  and  in  suspension. 
Some  of  these  impurities  are  organic  and  some  are  inorganic.  They 
consist  of  various  gases,  fluids,  and  solid  substances.  The  more  im- 
portant impurities  and  their  sanitary  significance  will  be  considered 
in  detail  under  the  chemical  analysis  of  water. 


CLASSIFICATION  OF  WATER 

From  a  sanitary  standpoint  water  is  either  good  or  bad.  Commonly 
waters  are  classified  as  pure  or  impure.  It  is  not  possible,  however, 
in  the  present  state  of  our  knowledge,  to  draw  a  sharp  line  of  distinc- 
tion. In  the  classical  reports  of  the  Massachusetts  State  Board  of 
Health  waters  are  spoken  of  as  normal  or  polluted.  A  normal  water 
is  free  from  direct  or  indirect  pollution  by  waste  products  from  human 
life  or  industries.  The  difficulty  with  this  classification  is  that  normal 
waters  may  differ  widely  in  color,  taste,  odor,  and  composition,  and  may, 
therefore,  be  unfit  for  household  or  manufacturing  purposes. 

Water  is  considered  pure  from  a  sanitary  point  when  it  contains  no 
evidences  of  pollution  from  the  wastes  of  man  or  animal,  and  is  con- 
sidered pure  by  the  engineer  when  it  contains  no  lime  or  salt  to  form 
boiler  scale,  or  organic  matter  in  sufficient  amount  to  cause  foaming. 

A  practical  classification  of  water  is  as  follows:  (1)  good,  (2) 
polluted,  (3)  infected.  A  good  water  may  be  defined  as  one  of  good 
sanitary  quality,  as  determined  by  physical  inspection,  bacteriological 
and  chemical  analyses,  a  sanitary  survey  of  the  watershed,  and,  finally, 
by  clinical  experience.  A  polluted  water  is  one  containing  organic 
waste  of  either  animal  or  vegetable  origin.  A  polluted^  water  is  a 
suspicious  water.  An  infected  water  contains  the  specific  microorgan- 
isms of  human  diseases.^ 

In  Europe  waters  are  frequently  classified  as  potable  or  non-potable. 
Many  cities  on  the  Continent  have  a  double  water  supply  with  faucets 

^  Sometimes  spoken  of  as  contaminated  water. 

"  Chemical  poisons  such  as  lead  are  not  included  in  this   classification. 


THE  USES  OF  WATEE  IN  THE  BODY  791 

plainly  labeled  "potable"  or  "non-potable,"  the  first  being  suitable  for 
drinking  and  cooking  purposes  and  personal  use,  while  the  second  is 
intended  for  miscellaneous  household  and  industrial  uses. 

According  to   location,  waters   are   considered   under   three   classes, 
viz.,  rain  water,  surface  water,  or  ground  water. 


PROPERTIES  OF  WATER 

Water  is  a  clear,  transparent,  tasteless,  and  odorless  fluid;  colorless 
in  small  quantities;  pale  blue  through  a  deep  column.  It  freezes  at 
0°  C.  and  boils  at  100°  C.  under  a  barometric  pressure  of  760  mm.  It 
is  practically  incompressible;  has  its  greatest  density  at  4°  C;  is  a 
remarkable  solvent.  The  latent  heat  of  water  and  other  properties 
that  have  a  sanitary  bearing  will  be  considered  in  the  succeeding  pages. 

Water  is  the  most  widely  distributed  substance.  The  hardest  crystals 
and  the  driest  rocks  contain  appreciable  quantities;  in  fact,  crystals 
could  not  form  were  it  not  for  the  action  of  water. 

Practically  all  substances  yield  to  water ;  it  is  the  most  universal 
solvent  known.  It  dissolves  gases;  in  fact,  one  of  the  most  important 
constituents  of  all  natural  waters  is  carbonic  acid.  Carbon  dioxid  is 
always  present  in  the  air,  and  all  rain  waters  contain  some  of  it.  Still 
more  is  taken  up  by  the  water  as  it  percolates  through  ground  covered 
with  vegetation.  The  presence  of  this  gas  increases  the  solvent  powers 
of  the  water,  enabling  it  especially  to  dissolve  limestone  and  many 
other  inorganic  substances. 


THE  USES  OF  WATER  IN  THE  BODY 

As  a  rule,  water  is  not  considered  a  food,  for  it  may  be  said  to 
have  little  or  no  value  when  estimated  as  a  force  producer  within  the 
body.  Much  of  the  water  which  is  either  drunk  or  ingested  as  a  part 
of  other  foods  passes  through  the  body  unchanged,  but  some  of  it  is 
undoubtedly  altered  or  split  up  into  elements  which  unite  with  other 
compounds.  The  nature  of  these  processes  is  obscure,  and  as  yet  very 
little  understood.  Water  is  entitled  to  rank  as  a  food  because  it  enters 
into  the  structural  composition  of  all  foods  as  w^ell  as  all  the  tissues  of 
the  body;  it  is  an  essential  element  of  diet,  even  though  it  cannot  of 
itself  build  tissue,  repair  waste,  or  produce  heat  or  energy. 

Water  composes  about  70  per  cent,  of  the  entire  body  weight,  and 
its  importance  to  the  system,  therefore,  cannot  be  overrated.  The 
elasticity  or  pliability  of  muscles,  cartilages,  tendons,  and  even  bones 
is  in  a  great  part  due  to  the  water  which  these  tissues  contain.     "The 


793  GENERAL  CONSLDERAWONS 

cells  of  the  body  are  aquatic  in  their  habits."  The  amount  of  water 
required  by  a  healthy  man  in  24  hours  is,  on  the  average,  between 
1,800  and  2,100  c.  c,  beside  about  600  c,  c.  taken  in  as  an  ingredient 
of  solid  foods,  thus  making  a  total  of  2,400-2,700  c.  e.  Twenty-eight 
per  cent,  of  the  loss  of  water  from  the  body  takes  place  through  the 
skin,  twenty  per  cent,  through  the  lungs,  fifty  per  cent,  through 
the  kidneys,  and  two  per  cent,  through  other  secretions  and  the 
feces. 

The  use  of  water  in  the  body  may  be  summarized  as  follows :  It 
enters  into  chemical  composition  of  the  tissues;  it  forms  the  chief  in- 
gredient of  all  the  fluids  of  the  body  and  maintains  their  proper  de- 
gree of  dilution,  and  thus  favors  metabolism;  by  moistening  various 
surfaces  of  the  body,  such  as  mucous  and  serous  membranes,  it  prevents 
friction;  it  furnishes  in  the  blood  and  lymph  a  fluid  medium  by  which 
food  may  be  taken  to  remote  parts  of  the  body  and  the  waste  material 
removed,  thus  promoting  rapid  tissue  changes;  it  serves  as  a  distributor 
of  body  heat;  it  regulates  the  body  temperature  by  the  physical  process 
of  absorption  and  evaporation. 

One  of  the  most  universal  dietetic  faults  is  neglect  to  take  enough 
water  into  the  system. 


THE  AMOUNT  OF  WATER  USED  AND  WASTED 

From  a  sanitary  standpoint  our  aim  should  be  to  encourage  a  gen- 
erous use  of  water,  but  to  discourage  waste.  The  conservation  of  pure 
water  and  the  economic  value  of  a  purified  water  are  pressing  problems 
that  a  growing  and  expanding  country  must  meet  and  solve  as  a  matter 
of  self-interest  if  not  of  self-preservation. 

It  is  possible  to  get  along  with  a  surprisingly  small  amount  of 
water.  Thresh  found  that  in  a  number  of  country  places  the  amount 
used  in  cottages  could  not  have  greatly  exceeded  one  gallon  per  person 
per  day.  This  is  not  sufficient  for  modern  requirements  of  cleanli- 
ness and  health. 

On  the  other  hand,  where  the  supply  is  abundant  and  easy  of  acces^ 
large  quantities  of  water  are  heedlessly  wasted. 

The  average  amount  of  water  per  capita  required  for  domestic  pur- 
poses is  usually  stated  at  about  17  gallons  a  day.  Eankine  considers 
10  gallons  sufficient.  Parkes  found  that  the  average  amount  used  by 
a  man  in  the  middle  class,  who  may  be  taken  as  a  fair  type  of  a  cleanly 
man  belonging  to  a  fairly  clean  household,  is  12  gallons  per  day.  This 
includes  the  amount  used  in  cooking,  drinking,  ablution,  utensil  and 
house  washing,  and  laundry.  Davies'  estimate  of  17  gallons  a  day  is 
divided  as  follows. 


THE  AMOUNT  OF  WATEE  USED  AND  WASTED        793 

Drinking,  3  pints;  cooking,  5  pints 1  gal. 

Ablution  (including  sponge  bath,  2^/^  gals.) 5    " 

Washing  (laundry,  3;  house,  etc.,  3) 6    " 

Water  closets 5    " 

17    « 


The  actual  per  capita  daily  consumption  of  water  in  some  cities  is, 
in  fact,  not  much  above  this  figure.  Thus,  Manchester  uses  20  gallons 
and  Berlin  22  gallons  a  day  for  each  individual.  Some  small  English 
towns,  as  Saffron  Walden  (population  6,108,)  use  11  gallons  per  cap- 
ita per  day,  and  Melrose  (population  1,300)  uses  13  gallons.  As  a 
contrast  to  these  low  figures  most  cities  in  America  are  furnished  with 
an  extravagant  quantity — Pittsburgh,  250  gallons  per  capita  daily,  Buf- 
falo, 223,  Philadelphia,  227,  Washington,  218.  The  small  amount  of 
water  used  by  some  European  cities  is  not  an  ideal  to  strive  for  under 
American  conditions.  The  European  figures  are  steadily  increasing, 
even  where  all  water  is  sold  by  meter.  In  towns  having  a  metered  sup- 
ply the  per  capita  consumption  varies  from  6.6  gallons  daily  for  the 
lowest  class  of  dwellings  to  59  gallons  for  the  highest  class  of 
dwellings. 

The  following  tables  give  the  per  capita  consumption  in  some  Ameri- 
can cities,  contrasted  with  similar  figures  abroad. 


The  quantities  of  water  supplied  in  a  number  of  American  cities 


Place 


Pittsburgh.  . 
Buffalo.  .  .  .. 
Philadelphia 
Washington . 

Chicago , 

Detroit .... 

Boston 

Cleveland.  .  , 
New  York. . 

Newark 

Milwaukee.  , 
Minneapolis 
Worcester. .  , 
Providence. 

St.  Paul 

Hartford. . . 

Lowell 

FaU  River .  . 


Gallons 

Percentage 

Year' 

per  capita 

of  Services 

Year  2 

Daily 

Metered 

1905 

250 

1 

1912 

1900 

233 

2 

1915 

1905 

227 

1913 

1906 

218 

3 

1915 

1900 

190 

3 

1913 

1905 

190 

29 

1912 

1905 

151 

6 

1915 

1905 

137 

68 

1915 

1902 

129 

35 

1915 

1900 

94 

21 

1915 

1905 

91 

94 

1915 

1904 

82 

42 

1915 

1900 

70 

94 

1915 

1905 

68 

86 

1914 

1900 

67 

28 

1915 

1906 

63 

100 

1915 

1905 

52 

69 

1915 

1905 

37 

97 

1915 

Gallons 

per  capita 

Daily 


236 

312 

178 

130 

218 

185 

104 

137 

66 

122 

127 

79 

84 

75 

61 

101 

57 

53 


Percentage 

of  Ser\'ices 

Metered 


20 
5 

'76 


60 
79 

"55 
99 
90 


64 

98 

78 

100 


*  From  Hazen's  "Clean  Water  and  How  to  Get  It." 
'From  official  sources  compiled  by  Dr.  J.  P.  Bill. 


794  GENERAL  CONSIDERATIONS 

The  quantUies  of  water  supplied  in  a  few  foreign  cities 


Place 

Year 

U.  S.  Gallons 

per  Capita 

Daily 

Place 

Year 

U.  S.  Gallons 

per  Capita 

Daily 

London 

Liverpool 

Paris          

1912 
1911 
1913 
1905 
1905 
1905 

36 
36 
69 
37 
63 
39 

Berlin 

Hamburg 

Dresden 

Copenhagen .... 
Brisbane 

1913 
1905 
1905 
1913 
1906 

24 
44 

26 

Amsterdam 

Melbourne 

Sydney 

32 

58 

The  amount  of  water  ^  expressed  by  the  per  capita  consumption 
of  a  community  is  very  misleading  for  purposes  of  comparison.  The 
figures  are  usually  obtained  by  dividing  the  total  theoretical  amount 
of  water  pumped,  by  the  population.  The  result,  therefore,  does  not 
take  into  account  many  factors,  for  the  actual  amount  of  water  pumped 
does  not  equal  the  theoretical  possibilities ;  corrections  for  slip  and  other 
factors  should  be  made.  The  figures  also  do  not  take  into  account  the 
amount  of  water  lost  through  broken  pipes,  leaky  joints,  etc.  It  is  esti- 
mated that  in  some  places  almost  half  the  water  pumped  is  wasted  in 
this  way.  According  to  Whipple,  the  water  lost  and  unaccounted  for 
with  metered  supplies  amounts  to  from  15  to  50  gallons  per  day  per 
capita.  Further,  there  are  great  discrepancies  when  contrasting  differ- 
ent cities  in  the  amount  of  water  used  for  business  purposes.  The 
amoimt  of  water  used  in  trades  and  manufactures  varies  enormously. 
Certain  industries,  such  as  mining,  tanneries,  coal  washing,  paper  mills, 
breweries,  wool  scouring,  etc.,  require  great  quantities.  It  is  estimated 
that  in  the  iron,  coal,  and  steel  regions  of  Pennsylvania  a  quantity  of 
water  representing  the  entire  flow  of  the  Allegheny  River  passes  through 
the  large  steel,  iron,  and  other  mills  along  its  banks  several  times  before 
it  reaches  the  city  of  Pittsburgh.  Therefore,  unless  the  per  capita  con- 
sumption  is  based  upon  the  amount  of  water  actually  measured  by  meter 
for  domestic  purposes,  the  figures  of  one  city  cannot  be  properly  com- 
pared with  those  of  another. 

Few  persons  realize  the  immense  amount  of  water  that  is  wasted 

in  almost  every  town.     Taking  it  right  through,  probably  one-half  of 

the  water  supply  of  American  cities  is  wantonly  wasted.     While  some 

of  this  is  unavoidable,  the  greater  part  of  it  could  be  stopped.     There  are 

three  principal  causes  of  this  waste:      (1)   leakage  from,  faulty  mams 

and  service  pipes;   (2)    waste  from  defective  house  fittings;   (3)   waste 

resulting  from  an  unmetered  or  unmeasured  service.     The  first  cause 

^It  has  been  calculated  that  altogether  the  supply  of  Rome  was  332,306,62-1 
gallons  daily,  which  would  have  been  over  332  gallons  per  capita  upon  a  basis 
of  a  population  of  one  million.  This  calculation,  however,  has  been  based  upon 
data  furnished  by  Prony  in  1817.  Mr.  Clemens  Herschel  has  lately  shown  a 
much  more  probable  figure  for  the  daily  water  consumption  of  Rome,  namely: 
32,000,000  U.  S.  gallons. 


THE  AMOUNT  OF  WATER  USED  AND  WASTED        705 

includes  leaks  from  faulty  mains  and  service  pi2:»es  and  all  other  hidden 
defects  where  the  water  escapes  unperceived  into  drains  and  sewers  or 
into  the  sub-soil.  It  is  possible  to  check  a  large  part  of  this  waste  by 
the  use  of  instruments  known  as  detectors.  With  these  instruments 
leaks  may  be  located.  The  detectors  are  of  two  sorts:  (1)  aquaphones, 
instruments  resembling  a  large  stethoscope,  by  which  a  trained  ear  may  . 
locate  murmurs;  (2)  pitometers,  instruments  which  measure  the  rate 
of  flow  in  branch  lines  during  the  small  hours  of  the  night,  when  prac- 
tically no  water  is  used.  In  this  way  leaks,  defective  taps,  and  open 
stopcocks  may  be  discovered.  It  requires  but  a  moment's  calculation  to 
figure  out  the  great  number  of  gallons  wasted  by  forgetting  to  close  a 
stopcock.  In  some  cities,  such  as  Washington,  in  the  winter  time  the 
water  in  many  houses  is  allowed  to  run  continuously  from  the  cold  water 
faucet,  in  order  to  prevent  freezing.^  The  waste  from  this  cause  is  enor- 
mous, and  may  be  corrected  by  properly  placing  the  service  pipes  so  as 
to  avoid  all  danger  from  bursting  through  freezing.  It  has  been  the 
universal  experience  that  much  water  is  thoughtlessly  wasted  where  the 
service  is  not  metered.  The  only  objection  to  a  metered  service  is  the 
prejudice  common  to  all  innovations,  but  the  advantages  are  soon  real- 
ized and  the  saving  is  very  considerable.  The  introduction  of  meters  in 
the  city  of  Washington  during  the  past  few  years  has  resulted  in  cheek- 
ing the  waste  by  reducing  the  total  amount  of  water  consumed  one- 
third,  making  a  saving  of  from  20  to  30  million  gallons  of  water  a  day 
without  annoyance  or  inconvenience  to  any  one.  This  great  saving  did 
not  all  result  from  the  metering  alone,  but  Was  aided  by  the  use  of 
detectors  and  an  efficient  system  of  inspection,  which  checked  waste 
from  other  causes.  In  Milwaukee,  before  meters  were  generally  adopted, 
the  water  used'  per  tap  was  1,781  gallons  per  day.  After  the  majority 
of  houses  were  furnished  with  meters,  the  amount  used  per  tap  was 
only  644  gallons.  Another  notable  instance  of  checking  waste  was  fur- 
nished by  Liverpool,  where  the  average  amount  supplied  daily  per  head 
was  33.5  gallons.  Deacons'  water  waste  detectors  were  introduced,  and 
these,  together  with  efficient  inspection,  reduced  the  supply  to  23  gal- 
lons without  any  restrictions  being  placed  upon  the  consumers.  At 
Shoreditch,  in  England  (population  87,000),  the  introduction  of  waste 
detectors  effected  in  the  course  of  three  years  a  diminution  of  waste 
and  undue  consumption  amounting  to  720,000,000  gallons  per  annum. 
At  Exeter  the  introduction  of  waste  detectors  reduced  the  waste  from 
75  to  12  gallons  per  head  per  day. 

It  is  estimated  by  engineers  that  45  per  cent,  of  the  water  supplied 
to  Manhattan  and  the  Bronx  is  wasted,  and  that  if  this  waste  were 
checked  the  new   aqueduct  from   the   Catskills,  which   is   costing  over 

^Tn  cities  whore  this  practice  prevails,  more  water  is  used  in  the  winter  time 
than  in  the  summer  months. 


^9G  GENERAL  OOXSTDEEATTONS 

$160,000,000,  would  nut  be  needed.  While  it  is  necessary  to  allow  a 
liberal  supply,  there  is  no  sanitary  advantage  in  waste.  Good  clean 
water  in  large  quantities  is  difficult  to  obtain  and  expensive.  Economy 
and  avoidance  of  waste  are,  therefore,  essential. 


DOUBLE  WATER  SUPPLIES 

The  question  of  a  double  supply  of  water,  one  cheap  for  general 
purposes  and  the  other  high  class  for  personal  use,  has  often  engaged 
the  attention  of  engineers  and  sanitarians.  Ancient  Eome  had  a  sort 
of  double  supply,  and  Paris  and  other  European  cities  have  it  at  pres- 
ent. The  advantages  and  disadvantages  of  the  double  system  are  evi- 
dent. Even  where  the  community  served  is  intelligent  and  careful, 
the  danger  of  a  double  system  is  very  great,  and  it  will  probably  never 
be  resorted  to  except  through  stress  of  circumstances. 

Sedgwick  has  recently  suggested  that  cities  may  be  given  a  double 
water  supply  provided  the  one  for  general  use  is  disinfected  or  de- 
natured in  such  a  way  as  to  discourage  its  nse  for  drinking  purposes. 
Thus,  if  the  second  supply  had  added  to  it  a  large  amount  of  bleaching 
powder,  perhaps  sufficient  to  make  it  distasteful,  it  would  at  least  be 
harmless  so  far  as  infections  are  concerned.  The  proposition  is  attrac- 
tive, and  would  serve  well  for  street  washing,  fire,  and  other  purposes. 


SOURCES  OF  WATER 

We  may  begin  the  circle  by  considering  that  all  water  comes  to  us 
from  the  aqueous  vapor  condensed  in  the  form  of  rain  or  snow.  Of 
this  a  certain  amount  returns  to  the  atmosphere  by  evaporation;  the 
rest  collects  upon  the  surface  of  the  earth  or  soaks  into  the  ground. 
Some  of  it  flows  oif  in  the  direction  of  surface  slope  to  join  the  ponds, 
lakes,-  rivers,  or  seas,  or  some  of  it  may  penetrate  the  earth  to  variable 
depths.  The  sources  of  our  water  supply  may,  therefore,  be  classified 
as:  (1)  rain  or  snow  water,  (2)  surface  water,  including  ponds,  lakes, 
streams,  and  rivers,  and  (3)  ground  water,  including  springs  and  wells. 
This  classification  is  evidently  an  arbitrary  one,  used  for  convenience. 
There  is  no  sharp  line  of  demarcation  between  rain,  surface,  and  ground 
water.  Rain  water  soon  becomes  surface  water,  and  surface  water 
quickly  passes  into  the  ground ;  the  ground  water  frequently  reappears 
as  springs  to  form  streams  and  lakes  and  other  surface  supplies. 

Rain  water  is  nominally  the  purest  and  may  be  free  from  all  traces 
of  organic  matter,  but  is  liable  to  irregularity  of  composition,  and  in 
built-up  sections  it  is  very  difficult  to  collect  it  so  as  to  be  free  from 


SOURCES  OF  WATER  TJH 

coiitamiuation  and  fit  for  drinking.  Surface  water  from  inhabited 
watersheds  is,  in  its  raw  condition,  never  entirely  safe  for  drinking 
purposes.  Ground  water  obtained  from  the  sub-soil  of  a  catchment 
area,  free  from  sources  of  pollution,  is  usually  of  a  satisfactory  char- 
acter. Artesian  water,  which  is  ground  water  obtained  from  the  deeper 
underlying  strata,  is  often  so  rich  in  mineral  matters  that  it  is  unsatis- 
factory for  most  uses.  The  various  sources  of  pollution,  its  character, 
and  dangers  will  be  considered  in  subsequent  pages. 

BAIN  WATER   ' 

Rain  water  is  really  "distilled  water,"  that  is,  it  is  water  that  has 
been  vaporized  and  then  condensed.  The  process  of  distillation  is  one 
of  the  best  known  methods  for  purifying  liquids  of  all  kinds.  All  the 
non-volatile  sul)stances  are  left  behind;  theoretically,  therefore,  rain 
water  should  approach  nearer  to  absolute  purity  than  any  other  kind 
of  natural  water.  However,  it  receives  impurities  from  the  moment 
it  condenses,  for  each  droplet  of  mist  is  formed  about  a  particle  of 
dust  in  the  air.  The  rain  drop  further  absorbs  gases,  and  as  it  drops 
through  the  air  collects  a  large  amount  of  the  "dirt"  floating  in  the 
lower  portions  of  the  atmosphere.  It  is  a  common  observation  how  a 
shower  will  wash  the  air  so  that  it  becomes  beautifully  clear  and  clean. 
The  impurities  collected  by  the  rain  before  it  reaches  the  surface  of 
the  earth,  while  considerable  in  amount,  are  practically  negligil^le  from 
a  sanitary  standpoint,  i^fter  rain  touches  the  earth's  surface  it  becomes, 
to  all  intents  and  purposes,  a  surface  water,  unless  collected  with  special 
precautions  to  avoid  contamination.  If  collected  from  a  clean,  impervi- 
ous surface  in  the  open  country,  it  is  the  purest  of  natural  waters.  The 
use  of  rain  water  for  drinking  purposes  has  met  with  little  favor  by 
sanitarians,  despite  its  exceptional  purity,  because  it  is  so  frequently  col- 
lected and  stored  in  such  a  careless  manner  that  it  is  subject  to  impuri- 
ties. It  is  true  that  rain  water  is  not  likely  to  be  infected  with  sewage, 
nevertheless  some  of  the  filthiest  waters  used  for  domestic  purposes  come 
from  rain-water  tanks.  Even  casual  inspection  will  often  show  that 
rain  water  collected  and  stored  in  the  usual  way  is  very  far  from  being 
pure,  though  rarely  infected. 

Because  rain  water  is  soft  it  recommends  itself  for  use  in  the  laun- 
dry, and  the  absence  of  lime  salts  renders  it  desirable  for  cooking.  On 
the  whole,  however,  it  is  not  considered  as.  practicable  as  a  good  ground 
or  surface  water  for  general  domestic  supply. 

The  use  of  rain  water  stored  in  cisterns  is  the  principal  factor  in 
keeping  yellow  fever  alive  in  endemic  foci.  The  yellow  fever  mos- 
quito {Stegomyia  calopus)  breeds  by  preference  in  artificial  containers 
holding  rain  water.     It  was  the  abolition  of  such  breeding  places  that 


798  GENERAL  CONSIDEKATIONS 

has  protected  Philadelphia,  Boston,  and  many  otlier  seaports  that  for- 
merly fostered  the  stegomyia  and  sufl'ered  from  yellow  fever  epidemics 
(see  page  237). 

Usually  it  is  advisable  to  filter  rain  water  collected  fi'om  the  roofs 
of  buildings,  especially  if  situated  in  towns,  near  dusty  roads,  etc. 

Underground  filters  for  rain  water,  in  order  to  purify  it  before  it 
enters  the  storage  tanks,  are  frequently  provided.  These  filters  are 
for  the  most  part  unsatisfactory.  Either  the  material  is  so  coarse  that 
little  purification  is  effected,  or  so  fine  that  it  speedily  becomes  clogged 
and  useless.  They  rarely  receive  proper  attention  and,  therefore,  are 
ajit  to  become  filthy. 

Amount. — The  average  annual  rainfall  on  the  globe  is  computed  to 
be  33  inches.  The  mean  annual  rainfall  for  different  portions  of  the 
United  States  has  been  tabulated  by  the  Uiiited  States  Weather  Bureau 
to  average  some  30  inches.  In  New  England  and  the  Middle  States  it 
amounts  to  40  inches.  In  Assam  from  600  to  805  inches  have  been 
recorded,  while  in  the  Sahara  desert,  part  of  Arabia,  the  desert  of 
Gobi,  and  portions  of  Mexico,  Chili,  and  Peru  it  has  seldom  been  known 
to  rain.  Coles-Finch  states  that  it  seems  to  be  a  fact  that  the  atmos- 
phere of  the  earth  is  growing  drier.  The  glaciers  are  retreating,  the 
Caspian  Sea  and  many  other  lakes  are  growing  smaller,  and  the  great 
deserts  seem  to  be  extending.  Some  of  the  richest  countries  on  earth 
have  seen  their  fertility  decreasing,  mainly  owing  to  lessened  rainfall, 
and  this  caused,  at  least  in  part,  by  the  ruthless  destruction  of  the 
forests.  Euined  forests  mean  flooded  rivers,  periodic  droughts,  eroded 
soil,  and  dried-up  springs. 

The  amount  of  water  given  by  rain  can  easily  be  calculated  if  two 
points  are  known — the  mass  of  rainfall  and  the  area  of  the  receiving 
surface.  The  amount  ■  is  determined  by  a  rain  gage  and  the  area  of 
the  receiving  surface  must  be  measured.  Roughly,  the  amount  may 
be  calculated  by  multiplying  the  area  of  the  receiving  surface  in  square 
feet  by  half  the  rainfall  in  inches,  the  result  being  in  gallons.  Here 
the  error  is  about  4  per  cent.  Thus,  according  to  Church,  one  inch  of 
rain  on  a  house  roof  20x20  feet  area  would  be  about  250  gallons.  With 
a  rainfall  of  40  inches  per  annum  this  would  amount  to  10,000  gallons, 
or  27  gallons  per  day. 

The  total  theoretical  amount,  however,  is  never  available,  for  the 
reason  that  some  is'  lost  by  evaporation  and  the  first  flow  should  be 
wasted. 

Only  a  very  small  proportion  of  water  may  be  collected  from  a  light 
shower  spread  over  a  considerable  interval,  especially  in  hot  weather, 
as  nearly  all  is  lost  by  evaporation. 

The  stations  of  Prussia  allow  the  following  average  for  evaporation^, 
the  amount  evaporated  in  the  open  fallow  field  being  called  100; 


SOTJECES  OF  WATEE 


799 


Evaporated 

Retained  More 
than  in  Open 
Fallow  Field 

Under  beech  growth 

Per  Cent. 
40.4 
45.3 
41.8 
90.3 

Per  Cent. 

59.6 

Under  spruce  growth 

54.7 

Under  pine  growth    

58.2 

From  cultivated  field 

9.7 

It  is  this  protection  against  evaporation  which  gives  to  tlie  forest 
its  chief  value  as  a  guardian  of  water  supply.  The  forest  floor,  with 
its  irregularities  and  its  sponge-like  qualities,  moreover  stops  the  rapid 
and  ruinous  draining  of  the  surface,  with  attendant  denuding  of  the 
land,  and  favors  slow  percolation  through  the  soil  and  reinforcement  of 
the  springs. 

The  amount  of  water  that  can  h»  utilized  from  the  rainfall,  drain- 
ing a  catchment  area,  may  be  stated  as  follows:  Taking,  for  example, 
an  average  of  46  inches  of  rainfall  ea'ch  year  upon  the  catchment  area, 
one-half  of  this  is  lost  by  evaporation  from  the  water  surfaces,  from 
the  surface  of  the  ground,  and  especially  from  the  leaves  of  all  the  plants 
and  trees  that  grow  upon  it.  The  other  half,  equal  to  a  rainfall  of  23 
inches,  flows  off  into  streams,  and  sooner  or  later  reaches  the  lake  or 
impounding  reservoir.  In  wet  years  the  amount  that  flows  off  is 
greater;  in  dry  years  it  is  less  than  the  average;  in  the  winter  and 
spring  months  the  flow  is  very  much  greater  than  at  other  times. 

Collection  and  Storage. — The  points  of  prime  importance  in  the  col- 
lection and  storage  of  rain  water  for  domestic  purposes  are:  (1)  the 
material  and  care  of  the  surface  upon  which  it  is  caught;  (2)  the  sep- 
aration of  the  first  flow,  which  contains  most  of  the  grossest  impurities ; 
(3)  the  location  and  construction  of  the  storage  cistern. 

Storage  cisterns  for  collecting  rain  water  are  frequently  placed  under- 
ground. In  some  places,  such  as  New  Orleans,  rain  water  cisterns  are 
built  of  cypress  wood  and  always  above  ground.  Tanks  of  wood  serve 
their  purpose  well,  provided  they  be  kept  full.  If  there  is  great  fluctua- 
tion in  the  water  line  the  tank  itself  falls  out  of  repair.  Eain  water 
attacks  iron,  lead,  zinc,  and  other  metals,  and  when  metal  cisterns  are 
used  the  metal  should  be  coated  with  a  good  asphaltum  paint.  This 
applies  also  to  the  delivery  pipe.  Under  no  circumstances  should  lead 
cisterns  or  lead  service  pipes  carry  rain  water  used  for  drinking  purposes. 
It  should  not  be  forgotten  that  cisterns  are  liable  to  the  grossest  kinds 
of  pollution,  and  they  require  frequent  inspection  and.  cleansing. 

Where  overflow  pipes  from  rain  water  tanks  are  connected  with 
drains  precautions  must  be  taken  to  prevent  sewage  backing  up  and 
entering  the  tank. 

Composition. — Eain  water  varies  in  composition  with  the  purity  of 


son  GENERAL  CONSTDERATIOT^TS 

the  atmosphere  through  which  it  has  passed.  It  always  contains  dis- 
solved gases,  an  average  of  25  c.  c.  per  liter.  These  gases  are  mainly 
nitrogen,  oxygen,  and  carhon  dioxid,  taken  up  in  proportion  to  their 
absorption  coefficients,  and  not  in  proportion  to  the  amount  contained 
in  the  atmosphere.  The  gases  contained  in  rain  water  consist  of  about 
G4  per  cent,  nitrogen,  34  per  cent,  oxygen,  and  2  per  cent,  carbon 
dioxid.  In  addition  ammonia  is  very  commonly  present.  The  amount 
of  total  solids  varies;  throughout  England  it  averages  0.39  part  per 
million.  The  principal  inorganic  constituent  of  rain  water  is  sodium 
chlorid;  nitric  acid  and  nitrates,  sulphuric  acid  and  sulphate;  a  small 
quantity  of  nitrogenous  organic  matter  is  also  present.  The  sodium 
chlorid  comes  mostly  from  the  sea  spray  lifted  into  the  atmosphere 
through  wind  action.  The  sulphuric  acid  comes  largely  from  the  waste 
products  of  burning  coal.  Eain  water  is  soft  on  account  of  the  absence 
of  the  alkaline  earths,  and  is  almost  always  acid  in  reaction.  It  has  a 
mawkish  taste. 

Bacteria. — Eain  water  contains  a  variable  number,  of  bacteria  and 
other  microorganisms,  the  number  and  kind  depending  upon  the  germ 
population  of  the  atmosphere  through  which  the  rain  passes.  Fortu- 
nately the  various  microorganisms  floating  in  the  air  and  carried  down 
mostly  by  the  first  shower  are  not  of  serious  moment,  as  far  as  health 
is  concerned.  Pathogenic  microorganisms  in  the  air  are  few  in  num- 
ber, and  these  are  soon  killed  by  desiccation  or  the  germicidal  action 
of  the  direct  sunlight,  to  which  they  are  so  thoroughly  exposed. 

Miquel,  at  the  Montsouris  Observatory  in  Paris,  found  rain  water 
to  contain  bacteria,  pollen,  spores  of  fungi,  protococci,  etc.,  especially 
numerous  in  the  warmer  months.  In  the  first  showers  after  a  long  spell 
of  dry  weather  over  100,000  such  organisms  may  occur  in  a  pint. 

SURFACE  WATERS 

Surface  waters  include  rivers,  creeks,  and  smaller  streams,  large  and 
small  lakes,  ponds,  and  impounding  reservoirs,  all  resting  upon  the 
bosom  of  the  earth  in  contact  with  the  atmosphere.  Surface  waters  vary 
greatly  in  composition,  depending  largely  upon  the  character  of  the 
catchment  basin.  A  water  flowing  over  a  rocky  soil  or  through  deep 
layers  of  sand  and  gravel  is  more  likely  to  be  free  of  organic  impurities 
than  one  that  is  drained  over  loam  or  has  stood  in  swamps'. 

From  the  way  in  which  surface  waters  are  exposed  they  are  subject 
to  impurities,  and  from  a  sanitary  standpoint  are  frequently  dangerous 
and  almost  always  open  to  suspicion.  Most  cities,  especially  in  America, 
depend  upon  surface  waters  for  their  supply.  This  is  usually  taken  from 
rivers,  lakes,  or  impounding  reservoirs.  It  is  scarcely  possible,  in  a  pop- 
ulous country,  to  obtain  a  large  quantity  of  surface  water  free  from 


SOUBCES  OF  WATEE  801 

pollution  witli  human  wastes.  Sanitarians  have,  therefore,  more  and 
more  come  to  the  conclusion  that,  while  surface  waters  used  for  drink- 
ing purposes  should  be  guarded  against  contamination,  as  far  as  prac- 
ticable, they  should  also  be  purified  before  they  are  used. 

Rivers. — Streams  are  the  natural  sewers  of  the  regions  they  drain, 
and,  when  used  as  a  source  of  water  supply,  we  have  established  a 
direct  connection  between  the  alimentary  canals  of  the  people  living 
upstream  with  the  mouths  of  those  below.  Most  of  our  large  rivers 
flow  through  more  than  one  state;  therefore,  the  interstate  pollution 
of  streams  becomes  a  national  problem.  In  the  older  countries  of  Eu- 
rope, with  more  centralized  power,  laws  to  prevent  the  pollution  of 
streams  are  enforced.  In  our  country  the  federal  authorities  are  not 
authorized  to  enforce  this  pressing  sanitary  problem  of  growing  im- 
portance.    This  is  discussed  more  in  detail  under  Sewage. 

In  our  country  the  rivers  furnish  the  chief  source  of  water  supply 
for  most  of  our  large  cities.  The  succession  of  cities  and  the  combined 
use  of  the  river  as  a  sewer  and  source  of  water  supply  on  such  rivers 
as  the  Merrimacl,  Hudson,  Delaware,  Ohio,  Missouri,  and  Mississippi 
are  particularly  impressive,  and  when  the  water  has  been  used  in  its 
raw  or  unpurified  state  much  unnecessary  sickness  has  resulted  and 
thousands  of  lives  have  been  lost  in  this  way. 

No  stream  draining  an  inhabited  region  can  be  considered  safe 
without  some  method  of  purification.  There  are  a  thousand  minor 
sources  of  pollution  that  practically  cannot  be  stopped,  even  though 
the  sewage  flowing  into  the  stream  is  treated  and  all  reasonable  pre- 
cautions taken  in  connection  with  it.  It  is  well  known  that  very  few 
sewage  purification  works  treat  all  the  sewage  from  the  districts  which 
they  serve.  Thus,  there  are  storm  overflows  and  the  street  wash  that 
cannot  pass  through  sewers,  and  other  sources  of  pollution. 

Looking  at  the  whole  matter  of  streams  pollution  solely  as  an 
economic  engineering  problem,  it  is  cheaper  to  purify  the  water  sup- 
plies taken  from  the  rivers  than  to  purify  the  sewage  before  it  is  dis- 
charged into  them.  The  volume  to  be  handled  is  less  and  the  cost  of 
purifying  water  per  million  gallons  is  much  less  than  the  cost  of  purify- 
ing sewage.  Further,  in  the  present  state  of  our  knowledge  water  may 
be  purified  more  effectively  and  with  greater  certainty  than  sewage. 
On  the  other  hand,  it  is  perfectly  clear  to  the  sanitarian  that  the  future 
will  require  both  methods,  that  is,  a  reasonable  protection  of  our  streams 
against  pollution  and  the  purification  of  the  water  served  to  cities. 

Composition. — The  composition  of  river  water  varies  very  much, 
according  to  the  part  of  the  river  whence  it  is  taken.  Near  its  source 
the  water  may  be  comparatively  pure,  but  it  soon  becomes  polluted. 
The  composition  is  complex,  as  the  water  of  rivers  consists  of  a  mixture 
of  rain  water  and  ground  water,  to  which  are  added  surface  impurities. 
27 


802  GENETJAL  CONSTDEEATTOX.S 

As  a  rule,  river  water  is  softer  than  ground  water,  but  contains  a  greater 
amount  of  organic  matter. 

Sudden  and  great  changes  in  the  cliaracter  of  river  water  are  to 
be  expected.  Other  changes,  slow  in  operation  but  serious  iji  result, 
come  from  the  increasing  pollution  Avith  sewage  from  a  growing  popu- 
lation upon  the  upper  regions  of  the  watershed. 

Eivers  are  generally  purer  near  their  source.  The  amount  of  impuri- 
ties increases  as  we  descend  the  stream,  since  the  water  courses  are 
the  natural  drainage  channels  of  the  country,  and  the  wastes  of  human 
life  and  occupation  as  well  as  the  scourings  of  the  land  find  their  way 
into  the  streams.  It  is  for  this  reason  that  rivers,  after  passing  through 
cultivated  valleys  with  cities,  towns,  or  settlements  along  their  banks, 
often  contain  a  very  great  amount  of  mineral  and  organic  matter.  Thus, 
the  Mississippi  at  Minneapolis  contains  only  18.6  total  solids  per  100,000, 
while  the  same  river  at  St.  Louis  contains  244.3  per  100,000. 

The  amount  of  mineral  matter  picked  up  by  a  stream  depends  largely 
on  the  geological  formation  of  the  country  and  the  erosive  power  of 
the  stream. 

Freqvient  attempts  have  been  made  to  correlate  the  flow  of  streams 
and  the  stages  of  the  river  with  the  outbreaks  of  disease,  especially 
typhoid  fever.  It  is  to  be  remembered  that  the  flow  of  streams  is  depend- 
ent in  most  cases  not  only  on  the  rainfall,  but  on  springs  of  local  origin. 
Typhoid  may  be,  and  usually  is,  independent  of  the  stage  of  the  river. 
Outbreaks  are  often  connected  with  sudden  freshets  following  a  long 
dry  spell,  and  the  explanation  seems  to  be  that  the  accumulated  filth 
is  thereby  washed  down  from  the  slopes  and  banks  of  the  stream.  When 
streams  are  very  low  the  flow  becomes  sluggish,  sedimentation  and  other 
factors  influencing  self -purification  take  place  in  comparatively  short 
distances;  when  the  river  is  high  the  rapid  flow  is  more  apt  to  bring 
fresh  and  virulent  infection.  The  decline  of  typhoid  fever  in  Allegheny 
in  1908  and  1909  was  coincident  with  an  exceptionally  low  stage  of  the 
river.  During  the  spring  and  fall  freshets,  when  the  water  is  cold  and 
the  current  swift,  the  danger  is  the  greatest.  In  other  words,  it  is  the 
rapidity  of  flow  or  the  time  consumed  rather  than  the  stage  of  the  river 
or  the  dilution,  that  is  most  often  responsible  for  typhoid  and  other 
infections  in  river  waters. 

If  typhoid  bacilli  are  discharged  into  a  stream  which  flows  at  a  rate 
of  5  miles  an  hour,  which  is  a  comparatively  quiet  stream,  and  accept- 
ing the  usual  figures  that  the  bacteria  may  die  in  5  days,  these  organ- 
isms could  be  carried  600  miles,  surely  far  enough  to  reach  some  do- 
mestic supply.  Hence,  it  may  be  concluded  that  any  pollution,  however 
.  remote,  is  apt  to  reach  some  consumer  unless  it  occurs  near  the  sea. 
Nevertheless,  the  Potomac  Eiver  at  Washington  seems  to  be  responsible 
for  little  or  none  of  the  typhoid  fever  in  that  city,  although  it  drains  an 


SOtJECKS  OF  WATER  803 

area  of  about  11,400  square  miles,  having  a  population  in  1900  of  about 
half  a  million  and  receiving  directly  the  sewage  of  some  45,000  persons. 
The  question  of  the  self-purification  of  streams  is  considered  on  page 
879. 

Lakes  and  Ponds. — Fresh  water  lakes  and  ponds  make  admirable 
sources  of  water  supply  when  kept  free  from  pollution  with  the  wastes 
of  human  life,  and  industry.  This  is  much  more  practical  than  in  the 
case  of  rivers,  on  account  of  the  limited  area  of  the  catchment  basin 
directly  draining  into  a  small  lake  or  pond.  Lake  water  is  apt  to  be 
soft  and  free  from  serious  organic  impurities.  In  large  lakes  the  dilu- 
tion of  accidental  contamination  is  enormous,  and  the  effects  of  time, 
storage,  sedimentation,  and  other  purifying  factors  have  a  good  chance 
of  exerting  their  maximum  influence.  The  problem  from  a  sanitary 
standpoint  is  quite  different  when  we  consider  large  bodies  of  fresh 
water,  such  as  our  Great  Lakes,  or  smaller  lakes  and  ponds. 

The  Great  Lakes. — The  lake  cities  suflier  most  from  the  mingling 
of  their  own  sewage  with  their  own  water  supplies.  This  is  avoided 
in  part  by  building  the  intakes  farther  out  into  the  lake  or  by  placing 
the  intakes  in  deep  water  at  points  where  there  seem  to  be  fairly  defi- 
nite currents,  bringing  fresh,  clear  water  from  the  body  of  the  lake  to 
the  intake.  The  currents  are  never  constant,  being  controlled  by  the 
wind,  hence  safety  cannot  be  secured  in  this  way.  Almost  every  lake 
city  has  at  one  time  or  another  sufEered  from  outbreaks  of  typhoid  fever. 
Chicago  has  cut  a  drainage  canal  to  keep  her  sewage  from  entering  the 
lake,  so  that  it  now  flows  through  tributaries  to  the  Mississippi  River. 
This  sanitary  reform  cost  the  city  of  Chicago  upward  of  $40,000,000,  and 
it  eliminates  the  sewage  of  a  large  part  of  the  city,  but  not  including  cer- 
tain areas  of  Evanston  and  the  north  side.  Despite  this  commendable 
piece  of  sanitary  engineering  designed  to  keep  the  water  clean,  it  is 
probable  that  in  time  Chicago  will  resort  to  some  method  of  purifying 
its  water  supply.  This  applies  with  equal  force  to  all  lake  cities  simi- 
larly situated. 

Hazen  points  out  that  in  the  smaller  cities  upon  the  lakes  the  min- 
gling of  the  sewage  and  water  may  be  relatively  just  as  important  as  in 
the  larger  ones.  They  have  less  money  to  spend,  their  intakes  do  not 
go  out  so  far,  their  sewers  are  apt  to  discharge  at  the  nearest  point, 
sometimes  directly  in  front  of  the  waterworks  intake.  The  water  may 
be  shallow  and  stirred  by  the  wind  to  the  bottom,  and,  in  short,  "Menom- 
inee's sewage  in  Menominee's  water  may  b*e  just  as  bad  as  Chicago 
sewage  in  Chicago  water." 

The  Great  Lakes  are  so  large  and  the  dilution  and.  time  intervals 
and  exposure  to  sun  and  air  are  so  great  that  there  is  practically  no 
chance  of  infection  being  carried  from  one  of  the  great  cities  to  another. 
Thus,  Chicago  sewage  would  scarcely  endanger  the  prrity  of  Detroit's 


804  GENEKAL  CONSIDEEATIONS 

water  supply,  even  with  no  drainage  canal.  The  little  city  of  St.  Clair, 
with  2,543  inhabitants,  only  45  miles  away,  is  far  more  dangerous  to 
Detroit.  In  the  same  way  Detroit's  sewage  is  probably  harmless  at 
Cleveland,  and  Cleveland  sewage  is  harmless  at  Buffalo.  The  sewage 
of  Buffalo,  however,  is  a  great  menace  to  those  drinking  the  water  at 
Niagara  Falls. 

Pollution  may  travel  a  variable  distance  in  large  lakes.  At  the 
mouth  of  the  Detroit  Eiver,  for  instance,  serious  pollution  was  shown, 
extending  normally  more  than  10  miles  into  the  lake,  and  at  other 
places  sewage  pollution  was  shown,  extending  as  far  as  18  miles  from 
the  shore.^  The  pollution  from  boats  passing  near  the  intake  may  also 
be  a  serious  menace. 

Most  of  the  cities  on  our  great  lakes  find  it  impracticable  to  extend 
water  pipes  into  zones  of  pure  water  on  account  of  the  great  cost  of  these 
extensions  and  the  engineering  difficulties  involved  in  placing  intakes 
beyond  a  70  ft.  depth.  Therefore,  in  most  instances,  our  lake  cities  can- 
not obtain  a  safe  water  supply  without  purification. 

Impounding  Reservoirs. — Impounding  reservoirs  are  artificial  ponds 
or  lakes,  usually  made  by  throwing  a  dam  across  a  narrow  valley.  Most 
impounding  reservoirs  are  made  along  the  course  of  a  small  stream. 

The  principal  use  of  impounding  reservoirs  is  to  hold  the  excess 
of  water  of  the  winter  and  spring  flows  aud  make  it  available  during 
the  summer  and  fall. 

The  impounding  reservoir  designed  to  furnish  New  York  City  with 
a  new  supply  of  water  to  supplement  the  Croton  system  will  be  the 
largest  artificial  reservoir  for  water  supply  in  America,  if  not  in  the 
world.  It  is  situated  in  the  Catskill  mountains,  and  is  made  by  dam- 
ming Esopus  Creek,  and  will  ultimately  hold  one  hundred  and  twenty 
billion  gallons  of  water.  Boston  is  supplied  from  impounding  reservoirs 
on  small  streams;  the  Cochituate  (1848),  the  Sudbury  (1878),  and  the 
Nashua  (1898).  The  Wachusett  reservoir  stores  the  combined  water 
from  the  smaller  sources  of  supply,  and  has  a  capacity  of  63,000,000,000 
gallons  of  water.  Baltimore  has  an  impounding  reservoir  upon  the 
Gunpowder  Eiver;  other  cities  similarly  supplied  are  Newark  and  Jer- 
sey City  in  New  Jersey ;  Worcester,  Cambridge,  and  Springfield  in  Massa- 
chusetts; New  Haven  and  Hartford  in  Connecticut;  Altoona  in  Penn- 
sylvania, and  Denver  in  Colorado;  San  Francisco  and  Oakland  in  Cali- 
fornia; and  numerous  other  smaller  cities.  From  a  sanitary  standpoint 
the  great  advantage  of  an  impounding  reservoir  is  that  it  drains  a  com- 
paratively small  area  that  is  amenable  to  control;  often  the  catchment 
area  is  in  uninhabited  hilly  or  mountainous  districts.  The  other  sani- 
tary advantage  lies  in  the  fact  that  benefit  is  taken  of  the  great  sanitary 
safeguard  of  storage.     Most  pathogenic  microorganisms  die  a  natural 

*Iiiternat.  Joint  Commission  of  the  U.   S.  and  Canada. 


SOUECES  OF  WATER  805 

death  during  the  time  that  the  water  is  stored  in  a  large  impounding 
reservoir.  In  Boston  it  is  estimated  that  the  water  is  stored  an  average 
of  30  days  before  it  reaches  the  consumer.  Few  non-sporulating  bacteria 
dangerous  to  man  can  live  so  long  in  water  under  natural  conditions. 

The  chief  disadvantage  of  impounding  reservoirs  as  storage  basins 
is  that  they  are  open  to  the  air  and  light,  and  thus  favor  the  growth 
of  algae  and  other  microscopic  organisms  responsible  for  objectionable 
tastes  and  odors.  Further,  the  stagnation  of  the  water  favors  the  ac- 
cumulation of  the  products  of  decomposition,  which  is  another  source 
of  evil  smells  and  vile  tastes.  The  stagnation  of  water  in  impounding 
reservoirs  and  small  lakes  and  ponds  deserves  special  mention. 

Stagnation  of  Water  in  Impounding  Reservoirs  and  Small  Lakes. — 
Hazen  points  out  that  in  our  climate,  when  a  reservoir  or  lake  is  more 
than  20  to  40  feet  deep,  the  upper  part  of  the  water  is  usually  in  cir- 
culation under  the  influence  of  the  wind,  and  the  lower  part  remains 
stagnant.  There  is  little  or  no  mixing  between  the  surface  water  and 
the  bottom  water,  except  for  two  short  periods  each  year,  one  in  the 
spring  and  one  in  the  fall.  These  periods  of  circulation  to  the  bottom 
are  known  to  waterworks  men  as  the  spring  turnover  and  the  fall  turn- 
over. 

During  the  summer  weather  a  blanket  of  warm  and,  hence,  light 
water  remains  at  the  surface.  This  layer  may  be  20  feet  in  small  reser- 
voirs, and  40  feet  in  great  lakes.  The  temperature  of  this  surface  layer 
may  reach  75°  or  80°  F.  or  more  in  midsummer.  The  wind  stirs  it  up 
to  a  certain  depth  (about  20  to  40  feet),  depending  upon  the  depth  of 
the  reservoir  and  the  force,  direction,  etc.,  of  the  winds. 

The  bottom  layer  is  cool  and  quiet.  As  the  air  temperature  falls 
with  the  approach  of  winter  the  surface  water  cools,  until  it  approaches 
that  of  the  bottom  water.  When  the  difference  in  temperature  between 
the  surface  and  bottom  layers  is  less,  the  wind  action  extends  deeper, 
until,  all  at  once,  often  when  the  wind  is  blowing,  vertical  currents 
arise,  so  that  all  the  water  in  the  reservoir  turns  over  and  mixes  from 
top  to  bottom.  The  mixing  continues  for  a  few  weeks,  until  the  tem- 
perature of  the  surface  water  falls  below  the  point  of  maximum  density, 
namely,  4°  C.  Then  the  colder  water  commences  to  accumulate  at  the 
top.  The  top  often  freezes  and  entirely  shuts  out  wind  action,  so  that 
the  period  of  winter  stagnation  is  even  more  quiet  than  the  summer 
period.  The  spring  turnover  is  caused  by  a  reversal  of  the  conditions 
causing  the  fall  turnover;  surface  water  is  warmed  until  it  reaches  the 
temperature  of  the  bottom  water,  when  the  upward  and  downward 
currents  take  place. 

It  can  readily  be  seen  that  this  phenomenon  has  much  to  do  with 
the  quality  of  the  water.  Thus,  the  organic  matter  upon  the  bottom 
of  almost  all  reservoirs  decomposes,  and  in  the  absence  of  oxygen  pro- 


806  GENET^AL  COXSTDET^ATTOXS 

duces  the  vile  (xlors  and  nasty  tastes  of  [)iilfcfa(ti(Hi.  '^riicse  odors  and 
tastes  aociimulate  in  the  bottom  water  until  the  fall  turnover;  then 
they  become  mixed  with  all  the  water  in  the  reservoir.  If  the  water  is 
drawn  from  the  reservoir  near  the  top,  as  it  usually  is,  there  will  be 
a  great  change  in  the  quality  of  the  water  on  the  day  of  the  fall  turn- 
over. The  surface  water  is  well  charged  with  oxygen,  and,  as  this  falls 
to  the  bottom,  it  oxidizes  and  neutralizes  some  of  these  products  of  de- 
composition. Tastes  and  odors  due  to  this  cause  may  be  removed  by 
aerating  the  water  by  means  of  fountains,  cascades,  falling  over  a  dam, 
or  any  other  similar  means.  For  a  further  discussion  of  this  interesting 
subject  see  Hazen's  "Clean  Water  and  How  to  Get  It." 

Stripping. — Stripping  consists  in  removing  the  organic  matter  of 
the  surface  soil,  which  is  to  become  the  bed  of  a  reservoir.  The  ob- 
ject of  stripping  is  to  diminish  the  amount  of  putrefaction  taking  place 
in  the  bottom  stagnant  water,  and  also  to  furnish  less  food  for  bac- 
teria and  algae.  A  number  of  the  reservoirs  in  Massachusetts  were 
first  stripped  at  considerable  expense.  It  has  been  found  that  in  the 
older  reservoirs  prepared  in  this  way  putrefaction  has  not  taken  place 
for  some  years,  although  in  some  cases  putrefaction  seems  not  to  have 
been  entirely  prevented,  even  at  the  outset.  Stripping  does  not  prevent 
objectionable  growths;  it  only  reduces  them  somewhat,  because  many 
of  the  organisms  do  not  need  or  make  use  of  the  organic  matter  of  the 
soil  as  their  food  supply.  The  algae  live  rather  on  the  mineral  mat- 
ters of  the  water  and  the  air,  and,  with  the  aid  of  the  sunshine,  they 
build  up  their  own  organic  matter,  precisely  as  the  higher  plants  do 
growing  in  soil. 

GROUND  WATER 

Water  which  is  taken  from  the  ground  by  means  of  wells  or  flow- 
ing naturally  from  the  ground,  as  in  springs,  is  usually  satisfactory, 
as  far  as  injurious  impurities  are  concerned.  The  surface  water  is 
greatly  purified  as  it  percolates  through  soil.  This  is  nature's  process 
of  filtration ;  the  organic  matter  is  oxidized,  the  bacteria  are  largely 
strained  out.  The  soil  can  take  care  of  a  large  amount  of  pollution, 
and,  if  not  overburdened,  or  if  it  has  no  cracks  or  crevices,  the  ground 
water  may  be  entirely  free  of  objectionable  organic  substances  and  bac- 
teria. In  passing  through  the  soil  the  water  takes  up  a  rather  large 
amount  of  carbon  dioxid,  which  is  set  free  from  organic  decomposition. 
The  water,  thus  acidulated,  has  a  greater  solvent  action  for  lime  and 
other  mineral  constituents,  so  that  ground  water  is  apt  to  be  harder  than 
surface  waters,  and  to  contain  a  larger  amount  of  dissolved  inorganic 
substances.  In  deeper  waters  the  solvent  action  is  favored  by  increased 
licat  and  pressure,  so  that  deep  wells  and  artesian  waters  are  frequently 


SOUECES  OF  WATER  807 

unfit  for  domestic  use  on  account  of  tlie  large  amount  of  inorganic 
impurities  which  they  contain,  such  as  lime,  iron,  common  salt,  etc. 

The  water  that  soaks  into  the  soil  finally  rests  upon  an  impervious 
stratum.  Such  water,  as  a  rule,  does  not  exist  in  the  ground  as  a  river  ^ 
or  lake,  but  occupies  rather  the  spaces  between  the  sandy  particles,  except 
in  limestone  formations.  Ground  water,  therefore,  in  any  quantity  is 
found,  as  a  rule,  in  sandy,  gravelly,  or  sandstone  formations. 

All  water  finally  reaches  a  certain  level,  where  it  ceases  to  pass 
downward,  and  is  then  directed  in  a  horizontal  plane,  forming  a  more 
or  less  continuous  bed  of  water.  This  is  knovm  as  the  ground-water 
table,  which  underlies  practically  all  the  earth's  surface.  It  is  tapped 
when  wells  are  sunk,  and  forms  springs,  lakes  and  marshes,  where  it 
reaches  the  surface. 

It  is  only  in  limestone  regions  that  the  ground  water  exists  as  flow- 


FiQ.  97. — Ground  Wateb.     A.  High  level.     B.  Low  level.     C.  Intermittent  spring. 

ing  rivers  or  in  large  bodies.     In  such  instances,  as,  for  example,  the 
mammoth  cave  in  Kentucky,  the  underground  river  may  appear  and 
disappear  suddenly.     The  sanitary  significance  of  water  from  limestone 
crevices  is  entirely  different  from  that  obtained  from  a  sandy  soil. 

The  surface  of  the  ground  water  does  not  follow  the  surface  of  the 
land,  but  more  approximately  the  contour  of  the  impervious  stratum  on 
which  it  rests.  It  crops  out  at  the  surface  here  and  there,  to  form  rivers, 
ponds,  lakes,  and  springs.  The  irregularity  of  the  surface  of  the  ground 
water  table  is  due  to  a  certain  extent  to  the  rainfall.  During  drought 
the  level  becomes  more  and  more  uniform,  until  it  may  become  quite 
horizontal. 

Movement. — In  most  cases,  except  where  water  lies  in  deep  depres- 
sions and  pockets,  the  ground  water  is  in  constant  lateral  motion.  This 
motion  is  usually  in  the  direction  of  outfall,  that  is,  toward  the  nearest 
large  body  of  water — =lake,  river,  or  sea.  That  is  why  fresh  water  may 
frequently  be  obtained  by  sinking  a  well  at  the  seaeoast.  In  some  places 
the  rate  of  lateral  flow  is  so  slow  as  to  be  almost  imperceptible ;  at  other 
places  it  is  comparatively  rapid.  Thus,  at  Munich,  Pettenkofer  esti- 
mated 15  feet  per  day;  at  Budapest,  Fedor  found  the  ground  water  to 

^  Leipzig  and  Pueblo  both  take  their  water  supply  from  underground 
"rivers"  flowing  through  coarse  gravel.  In  Leipzig  the  stream  is  2  miles  wide, 
40  feet  deep  and  covered  by  6  feet  of  soil;  it  probably  represents  the  bed  of 
an  old  river. 


808  GENERAL  CONSIDERATIONS 

flow  at  an  average  of  167.6  feet  per  day.  The  rate  of  movement  is  de- 
pendent upon  the  pressure  behind  and  the  inclination  or  grade  along 
which  it  flows.  Slicliter  ^  estimates  that  with  a  temperature  of  50°  F. 
a  porosity  of  32  per  cent,  and  a  pressure  gradient  of  10  ft.  to  the  mile, 
water  has  been  estimated  to  travel  in  a  year  in  fine  sand  528  feet,  in 
medium  sand  216  feet,  in  coarse  sand  845  feet,  in  fine  gravel  5,386  feet. 
The  rate  of  flow  of  ground  water  may  be  determined  approximately  by 
several  methods. 

The  method  of  determining  the  velocity  of  ground  water  which  has 
been  used  with  satisfactory  results  by  Thiem  is  as  follows : 

Three  or  four  borings  are  sunk  to  ground  water  in  a  line  in  the 
direction  of  flow.  A.  large  dose  of  salt  is  then  put  into  the  upper  hole, 
and  at  frequent  intervals  analyses  are  made  of  water  drawn  from  each 
hole  below,  until  the  salt  content  has  reached  its  maximum  in  each  case, 
and  the  rate  of  movement  is  computed  from  these  results. 

Amount. — The  amount  of  water  that  may  be  obtained  from  the 
ground  can  only  be  determined  by  means  of  actual  pumping  tests  car- 
ried on  for  a  sufficient  length  of  time  to  bring  about  an  approximate 
state  of  equilibrium  between  the  supply  and  the  demand,  as  determined 
by  the  level  of  the  ground  water.  It  is  rarely  practical  to  continue  such 
tests  until  perfect  equilibrium  is  reached,  for  in  many  cases  several 
years  of  operation  would  be  required  to  determine  the  ultimate  capacity 
of  a  source.  Pumping  tests  of  short  duration  are  apt  to  be  very  decep- 
tive, as  ground  water  may  exist  in  the  form  of  a  large  basin  or  reservoir 
with  very  little  movement,  corresponding  to  a  surface  pond  with  small 
watershed,  and  brief  tests  would  give  little  more  information  than  sim- 
ilar tests  on  a  pond. 

It  is  easier  in  proportion  to  get  a  little  ground  water  than  to  get 
a  large  amount,  and  for  this  reason  ground  water  supplies  are  more 
generally  available  for,  and  better  adapted  to,  the  needs  of  small  places 
than  of  large  cities. 

In  Europe,  ground  water  supplies  have  been  secured  for  many  large 
cities;  there  has  been  no  corresponding  development  in  America.  The 
reasons  for  the  greater  use  of  this  method  of  supply  in  Europe  are: 
smaller  quantity  of  water  required  per  capita,  more  favorable  geologi- 
cal conditions,  and  more  study  given  to  the  subject  and  greater  efforts 
to  secure  them,  especially  in  Germany. 

Ground  water  may  be  obtained  from:  (1)  sand  and  gravel  deposits, 
(2)  sandstone  rock,  (3)  limestone  formations. 

Temperature. — The  temperature  of  ground  water  at  a  depth  of  50 
feet  is  practically  constant  and  is  the  same  as  the  mean  atmospheric 
temperature  of  the  region  under  which  it  lies.     Below  50  feet  the  tem- 

^  Slichter,  C.  S. :  "The  Motions  of  Underground  Waters^"  Water  Supply 
Paper  67,  U.   S.  Geological  Survey,   1902. 


SOURCES  OF  WATER  809 

perature  increases  1°  for  each  60  feet  in  depth,  on  an  average.  Waters 
lying  less  than  50  feet  below  the  surface  are  colder  in  winter  and 
warmer  in  summer,  as  they  are  acted  upon  by  external  climatic  condi- 
tions. Waters  reaching  the  surface  at  hot  springs  must  come  from 
deep  sources  as  many  of  them  have  a  temperature  of  at  least  180°  F. 
Fuller  states  that  springs  with  a  temperature  of  over  150°  F.  are  rare, 
if  they  occur  at  all  outside  of  igneous  regions.  As  this  temperature  rep- 
resents only  a  depth  of  5,000  feet  it  is  readily  seen  that  we  have  ordi- 
narily no  truly  deep  seated  springs  whatever. 

Ground  Water  from  Sand  and  Gravel  Deposits. — Water  flows  through 
sand  with  some  difficulty.  From  a  given  pumping  station  it  is  only  pos- 
sible to  draw  the  water  from  a  limited  distance.  This  distance  depends 
upon  the  depth  and  coarseness  of  the  sand.  Therefore,  the  only  way  to 
secure  a  large  quantity  of  water  from  such  formations  is  by  the  use  of 
a  number  of  comparatively  small  pumping  stations,  separated  so  as  not 
to  draw  from  the  same  territory. 

Only  a  given  amount  of  water  can  be  secured  from  a  square  mile 
of  ground.  The  amount  depends  upon  the  rainfall,  upon  the  evapora- 
tion from  the  surface  of  the  ground  from  transpiration  of  vegetation, 
and  upon  the  amount  of  storage  in  the  pores  of  the  soil. 

Most  of  the  sand  deposits  of  our  country  are  not  practically  available 
for  water  supply  purposes,  because  the  g-rains  of  sand  are  too  small 
and  the  flow  of  water  through  them  is  too  slow.  It  is  only  the  coarse- 
grained sands  that  are  practically  available. 

A  few  cities  in  America  obtain  their  drinking  water  supplies  from 
ground  water  obtained  from  sand  and  gravel  deposits.  At  Brooklyn  the 
conditions  are  particularly  favorable,  and  it  is  estimated  that  78  mil- 
lion gallons  of  ground  water  are  obtained  each  day  for  that  city.  For 
this  purpose  24  separate  pumping  stations  are  used.  The  water  sup- 
plied to  Camden,  N.  J.,  is  obtained  from  the  ground  through  wells 
close  to  the  Delaware  River,  and  the  amount  is  increased  by  taking 
river  water  from  the  surface  of  some  of  the  ground  about  the  wells. 
This  water  filters  through  the  sand  slowly  and  is  well  purified.  This 
method  of  adding  to  the  yield  of  wells  is  used  in  some  places  in  Ger- 
many and  France.  Memphis,  Tenn.,  is  probably  the  largest  city  of  the 
United  States  supplied  entirely  with  water  drawn  from  sand  and  gravel 
deposits.  In  this  case  the  water-bearing  area  is  several  hundred  feet  be- 
low the  surface,  and  is  below  a  clay  layer.  Lowell,  Massachusetts,  ob- 
tains ground  water  from  three  stations,  draining  different  areas  of  glacial 
drift. 

Filter  galleries  or  excavations  in  sandy  materials  near  river  banks 
have  been  used  in  the  past.  Such  water  corresponds  in  all  practical 
respects  to  the  ground  water  obtained  from  sand  and  gravel  deposits 
by  means  of  wells.     The  wells  are  preferable,  as  they  allow  water  to 


810  OENF.EAL  COXSTDE'RATTOX.S 

be  drawn  at  a  lower  level,  and  this  tends  to  a  drainage  of  a  greater  area, 
thereby  securing  a  larger  quantity  of  water. 

Filter  galleries  are  apt  to  furnish  a  diminishing  supply,  because  the 
pores  of  the  filtering  material  become  filled  with  the  sediment  of  the 
river  water.  When  this  happens  there  is  no  way  of  renewing  the  source. 
In  some  torrential  streams  the  filtering  surface  is  renewed  from  time  to 
time,  but  this  usually  does  not  occur. 

Ground  water  obtained  from  sand  and  gravel  deposits  is  usually 
clean  and  free  from  unwholesome  impurities.  Nevertheless,  many  towns 
and  cities  which  were  formerly  supplied  with  such  water  were  com- 
pelled to  seek  other  sources,  because  sufficient  water  was  not  obtainable 
from  the  ground  to  supply  the  increasing  quantities  required  by  rapidly 
growing  population. 

Ground  Water  from  Sandstone  Rock. — The  method  of  driving  wells 
in  sandstone  rock  difPers  from  that  in  driving  wells  in  sand  or  gravel, 
but  the  collection,  storage,  and  flow  of  water  are  precisely  the  same. 

The  cementing  material,  which  binds  what  otherwise  would  be  loose 
sand  into  a  solid  rock,  often  seems  to  offer  but  little  resistance  to  the 
flow  of  water,  and  the  sandstone  for  water  supply  purposes  acts  as  so 
much  sand  would  act. 

Water  drawn  from  sandstone  is  always  well  filtered.  It,  however, 
is  usually  limited  in  amount,  and,  while  of  the  greatest  value  for  small 
supplies,  is  not  available  for  large  communities. 

The  Marshall  and  Potsdam  sandstone  underlying  parts  of  Michigan, 
Illinois,  Wisconsin,  and  Minnesota  are  used  extensively  for  supplying 
towns  and  small  cities.  Thus,  Jackson,  Mich.,  with  a  poj)ulation  of 
over  25,000,  is  one  of  the  largest  cities  so  supplied. 

Ground  Water  from  Limestone  Formations. — In  limestone  formations 
the  underground  flow  of  the  water  is  not  through  sandy  or  porous  rock, 
for  limestone  is  not  porous.  The  water  travels  through  fissures  or  pas- 
sages. When  these  are  large  they  are  called  caverns  or  caves,  as,  for 
example,  the  Mammoth  Cave  in  Kentucky.  These  caverns  or  caves  are 
natural  seams  or  cracks  enlarged  by  the  gradual  solution  and  removal 
of  the  limestone  by  the  passing  water.  Limestone  is  the  only  common 
rock  that  is  soluble  in  this  way,  and,  for  water  supply  purposes,  lime- 
stone formations  must  be  distinguished  from  all  others. 

The  crevices  may  be,  and  often  are,  continuous  for  many  miles. 
They  are  remarkably  tortuous  and  anastomose  freely,  and  the  direction 
and  flow  of  the  water  bear  no  relation  whatever  to  the  surface  topog- 
raphy. Pollution  at  one  point  may,  therefore,  endanger  those  using 
the  water  at  a  far  distant  place. 

Limestone  formation  has  little  ability  to  hold  the  abundant  winter 
flows  to  maintain  a  supply  through  droughts.  The  difference  between 
limestone  and  sand  in  this  respect  is  strikiiig,  and,   from   a   sanitary 


SOUECES  OF  WATER 


811 


pDOD 

QOQQ' 
ODDOC 


standpoint,  the  fact  that  water  flowing  through  sand  is  filtered  and 
purified,  whereas  no  such  action  takes  place  through  limestone  fissures, 
is  significant.  While  much  water  is  frequently  available  at  one  point 
in  limestone  formations,  the  amount  is  subject  to  greater  fluctuations, 
and  the  supply  may  fall  short  when  most  needed. 

That  contamination  at  one  point  may  soon  reappear  at  a  far  distant 
point  may  be  demonstrated  by  the  use  of  fluorescent  dyes,  or  by  the  use 
of  massive  cultures  of 
some  harmless  micro- 
organism, such  as 
yeast  or  Bacillus  pro- 
digiosus. 

In  our  country 
San  Antonio,  Texas, 
is  supplied  with  water 
from  limestone  springs 
flowing  in  greater  vol- 
ume. Indianapolis 
was  at  one  time  and 
Winnipeg  in  Canada 
is  still  supplied  large- 
ly from  this  source. 
Paris  in  France  is 
partially  supplied  with 
limestone  water.  Vi- 
enna obtains  its  sup- 
ply from  the  wonder- 
ful Kaiserbrunnen 
and  other  limestone 
sources,  which-  are  all 
in  the  high  mountains, 
where  there  is  scarcely 
any  population  or  pol- 
lution. This  supply  is  mainly  from  the  melting  ice  and  snow  of  the  high 
mountains  which  replenishes  the  springs,  so  that  the  amount  of  water 
obtainable  is  greater  in  summer  than  winter. 

Typhoid  fever  has  been  caused  rather  frequently  by  the  use  of  ground 
water  from  limestone  formations.  This  has  been  demonstrated  in  Paris, 
Switzerland,  France,  and  England.  Water  supplies  from  limestone  for- 
mations must,  therefore,  be  regarded  with  suspicion. 

Wells. — A  well  is  nothing  more  or  less  than  a  hole  sunk  into  the  earth 
to  reach  a  supply  of  water  and  fitted  with  some  mechanical  arrangement 
for  lifting  the  water  to  the  surface.  Wells  may  be  either  shallow  or  deep, 
dug,  drilled,  driven,  punched,  or  bored.     The  type  depends  upon  the 


^im 


Fig. 


98. — Usual   Method   of  Pollution  and   even 
Infection  of  Wells. 


812 


GENERAL  CONSIDERATIONS 


CLAY 


I     / 

i    / 


nature  of  the  material  throni^h  which  the  well  is  s^^^k.  By  a  shallow 
well  is  usually  understood  one  which  is  dug  and  lined  with  stone  or 
brickwork.  The  cylinder  is  usually  5  or  G  feet  in  diameter  and  rarely 
over  30  feet  deep.  Driven  wells  are  made  hy  driving  an  iron  pipe  into  a 
sandy  or  gravelly  soil.  The  iron  pipe  is  perforated  near  its  pointed  end, 
for  the  entrance  of  the  water.  By  deep  wells  are  meant  drilled  or  the  so- 
called  artesian  wells.  They  consist  of  an  iron  pipe  or  tube  6  to  8  inches 
in  diameter,  and  may  extend  many  hundred  feet  into  the  earth.  If  the 
water  is  drawn  from  a  depth  of  100  feet  or  more  without  passing  an  im- 
pervious stratum,  the  well  is 
coNCEETE  usually  spoken  of  as  a  deep 
well.  If  the  well  passes 
through  an  impervious  strat- 
um into  a  pervious  one  be- 
neath, in  which  the  water  rests 
upon  another  impervious  strat- 
um, it  is  spoken  of  as  an  ar- 
tesian ^  well.  Water  is  usually 
pumped  from  the  wells  either 
by  means  of  the  ordinary  suc- 
tion pump  or  by  means  of  com- 
pressed air. 

Contrary  to  the  generally 
accepted  opinion  wells  are  usu- 
ally polluted  from  the  surface 
and  not  from  the  sub-soil  drainage.  The  filtering  power  of  the  soil  is 
"usually  sufficient  to  protect  the  water  drawn  from  a  well,  unless  (1)  the 
soil  is  overburdened  with  organic  matter,  or  (2)  a  cesspool,  broken 
sewer,  or  other  gross  source  of  pollution  is  very  close,  or  (3)  channels, 
fissures,  or  crevices  fexist  in  the  soil  and  sub-soil  so  that  imi^urities  reach 
the  well  without  undergoing  the  process  of  biologic  filtration. 

In  locating  a  well,  therefore,  much  depends  upon  the  surface  config- 
uration of  the  ground,  the  character  of  the  soil,  and  the  proximity  of 
possible  sources  of  pollution.  The  casing  of  the  well  should  be  sound 
and  tight,  preferably  of  brick  laid  in  cement  mortar,  pointed  on  the 
inside.  This  impervious  casing  should  extend  as  deeply  into  the  well 
as  practicable,  and  after  it  is  laid  the  outer  space  between  the  casing 
and  the  earth  should  be  filled  in  with  well-tamped  clay  soil  or  concrete. 
One  of  the  most  important  points  in  the  construction  of  a  shallow  well 
is  to  extend  the  casing  at  least  18  inches  above  the  surface  of  the 
ground  and  to  build  around  it  a  shield  of  concrete  or  brick  laid  in  cement 
extending  in  a  circle  from  the  top  of  the  well  3  or  4  feet  wide.     This 

*The  word  "artesian"  is  derived  from  Artois,  an  ancient  province  in  France 
which  was  supplied  Avith  flowing  wells. 


Fig.  99. — Proper  Construction  of  a  Well. 


SOUECES  OF  WATER 


813 


shield  should  join  the  well  casing  so  as  to  make  a  tight  joint  with  the  cas- 
ing. The  floor  of  the  well  should  rest  upon  the  top  of  the  casing,  so  that 
no  space  is  left  for  frogs,  mice,  or  bugs  to  crawl  in.  The  floor  should 
likewise  he  water-tight,  and  is  best  made  of  reinforced  concrete  with  a 
cement  surface.  If  this  is  not  practicable,  it  should  be  made  of  sound, 
hard,  tong-ue-and-grooved  boards  well  driven  up,  and  the  edges  painted 
with  white  lead.  Upon  this  should  be  laid  another  floor  of  similar 
material  at  right  angles  to  the  first.  The  pump  should  be  let  into  the 
floor  and  firmly  fastened  to  it,  and  protected  with  a  flashing  of  tin  to 
prevent  water  washing  back  into  the  well. 


Fig.  100. — Poptjlae  Idea  of  How  Wells  Become  Infected  from  Surface  Pollu- 
tion. This  probably  rarely  takes  place  in  rural  districts,  as  the  soil  can  usually  hold 
back  most  of  the  impurities.  The  danger  is  great,  however,  where  fissures,  cracks, 
or  crevices  exist,  or  where  sewage  enters  beneath  the  surface  of  the  soil  from,  broken 
drains  or  leaky  privies,  especially  in  limestone  formations. 

The  widely  prevalent  idea  that  some  form  of  ventilation  must  be 
provided  for  a  well  is  entirely  unnecessary.  Well  water  keeps  better  in 
the  dark  and  protected  from  the  outer  air. 

The  top  of  driven  wells  should  be  as  carefully  protected  as  those 
just  described  for  a  dug  well,  as  otherwise  the  polluted  surface  water 
may  work  down  the  sides  of  the  pipe.  Care  should  be  taken  that  the 
pipes  of  a  driven  well  near  the  surface  of  the  ground  do  not  rust  and 
become  leaky.  Such  wells  should  be  provided  with  a  heavj^  top,  to 
which  the  pump  frame  should  be  tightly  bolted,  in  order  to  prevent 
the  loosening  of  the  joints  in  the  pipe  by  the  vibration  of  pumping. 
The  ground  about  all  wells  should  be  kept  clean,  and,  where  possible,- 
should  be  turfed.  The  waste  water  should  be  carried  by  pipes  to  a 
considerable  distance  from  the  well. 


814 


GENEEAL  CONSIDETlATIO:t^S 


Artesian  water  and  water  from  deep  wells  furnish  the  safest  and 
most  satisfactory  sources  of  supply  Ave  have.  Such  water  is  usually 
clear  and  of  high  sanitary  quality.  Sometimes  such  waters  contain  a 
large  amount  of  inorganic  impurities,  whicli  render  them  unfit  for  do- 
mestic purposes.  Frequently  they  contain  iron  in  tlie  ferrous  state, 
which  soon  oxidizes  upon  contact  with  the  air  and  is  thrown  out  as  an 
insoluhle  ferric  salt,  which  renders  the  water  yellowish  or  hrownish. 
Deep  well  waters  may  also  contain  an  excess  of  lime  salts  or  common 
salt. 


Fig.  101. — Depression  of  the  Ground  Water  Level  by  Pumping  and  Tendency  to 
Draw  Nearby  Pollution  from  the  Soil  or  Cesspool. 


Water  from  shallow  wells  obtained  from  sandy  or  gravelly  forma- 
tions are  entirely  satisfactory,  provided  there  are  no  nearby  sources  of 
pollution.  The  proximity  of  well  and  privy  may  be  especially  hazard- 
ous. Shallow  wells  in  limestone  regions  must  be  carefully  guarded  and 
always  looked  upon  with  suspicion. 

It  is  evident  that  in  a  densely  inhabited  area  with  miles  of  sewers, 
some  of  them  doubtless  broken  or  leaky,  and  with  the  thousands  of  privy 
vaults  which  still  survive  in  most  of  our  American  cities,  we  have 
a  more  or  less  sewage-polluted  condition  of  the  soil  favorable  for  the 
contamination  of  shallow  wells.  Shallow  wells,  on  general  principles, 
have  been  gradually  eliminated  from  all  large  cities  having  an  abundant 
water  supply.  This  danger  was  well  shown  in  the  studies  upon  typhoid 
fever  in  the  District  of  Columbia,  in  which  many  of  the  shallow  wells 
situated  within  the  city  limits  were  shown  by  chemical  and  bacterio- 
logical analyses  to  be  polluted. 

Wells  may  be  disinfected  with  lime,  which  has  been  found  to  be 
fairly  effective.     A  mixture  of  carbolic  acid  and  sulphuric  acid  in  suffi- 


SOUECES  OF  WATEE 


815 


cient  quantity  will  sterilize  a  well,  Ijut  these  substances  have  evident 
objections.  The  method  of  injecting  steam  under  a  pressure  of  two 
atmospheres  has  been  used.  The  steam  is  forced  into  the  water  until 
the  temperature  is  brought  to  near  the  boiling  point.  Bleaching  powder, 
however,  is  the  cheapest  and  most  practical  method  of  disinfecting  wells 
that  need  such  purification. 

Springs. — A  spring  is  a  stream  of  water  emerging  from  the  ground, 
its  flow  being  due  to  natural  causes.  Spring  water  does  not  differ  in 
any  essential  particular  from  the  ground  water  obtained  from  shallow 


FiQ.  102. — In  a  Limestone  Formation  It  Is  Difficult  to  Tell  Anything  about  the 
SouBCE  OF  Water  Obtained  from  a  Well. 


wells.  Springs  may  be  regarded  as  natural  wells,  outcropping  where 
the  geological  formation  is  favorable.  Spring  water,  as  a  rule,  ia  of  a 
high  degree  of  purity,  and  as  the  water  flows  spontaneously  it  can  easily 
be  utilized ;  and,  as  no  form  of  machinery  is  necessary  to  pump  it,  it  is 
less  subject  to  contamination  than  well  water.  Spring  waters  differ 
greatly  in  character,  depending  upon  the  temperature  of  the  water 
and  the  inorganic  constituents  which  it  contains.  Springs  may  be 
perennial,  the  flow  being  constant  or  intermittent. 

Fuller  classifies  springs,  according  to  their  origin,  as  gravity  and 
artesian ;  and  according  to  the  kind  of  passages  traversed  by  the  water, 
as  (see  page  811)  tubular  and  fissure  springs. 

Some  of  the  largest  flowing  springs  are  found  in  Florida,  notable 
among  these  being  the  Silver  Spring  with  an  estimate  flow  of  368,913 


816  GENERAL  CONSlDElfATIOXS 

gallons  per  minute,  and  Blue  Springs  with  a  flow  of  349,1^50  gallons 
per  minute. 

Springs  may  be  polluted  from  various  sources,  and  in  much  the  same 
way  that  wells  are  polluted.  The  overlying  porous  layer  of  soil  may  be 
too  thin  to  remove  the  contamination  of  surface  washings  from  privies, 
stables,  hog  pens,  and  other  sources  of  contamination.  This  is  prob- 
ably not  a  frequent  source  of  danger  in  such  waters.  Springs  may  be 
contaminated  from  surface  washings ;  that  is,  the  infective  material  may 
be  washed  down  and  into  the  spring  by  heavy  rains,  and,  unless  the 
spring  has  a  bold  flow,  the  polluting  material  may  remain  in  it  for 
some  time.  Leaky  cesspools  above  a  spring  may  carry  dangerous  mate- 
rial almost  directly  into  the  water,  just  as  they  endanger  wells  in  pre- 
cisely the  same  way. 

The  protection  of  a  spring  against  contamination  requires  a  careful 
study  of  each  location.  Stables,  hog  pens,  and  privies  should  be  distant, 
and,  if  possible,  on  another  slope.  Soil  pollution  must  be  prevented  in 
the  neighborhood  of  the  sjDring,  and  animals  kept  away,  and  special  re- 
gard must  be  had  for  the  location  and  character  of  the  privy.  The 
spring  should  be  protected  above  with  a  masonry  or  concrete  wall.  This 
should  extend  well  into  the  ground,  so  as  to  guard  against  surface 
washings.  A  ditch  should  be  dug  to  carry  off  the  surface  water  around 
both  sides  of  the  spring,  and  the  neighborhood  kept  clear  of  weeds  and 
growth.  It  is  well  to  plant  grass  about  the  spring  so  as  to  keep  out  dust 
and  prevent  erosion  of  the  soil. 

In  limestone  regions  springs  are  subject  to  the  danger  already  spoken 
of  in  the  case  of  wells.  A  spring  in  such  a  region  may  be  the  same 
underground  stream  that  runs  through  the  neighbor's  back  yard  and 
disappears  in  his  meadow.  A  limestone  spring  that  becomes  muddy 
soon  after  a  rain  should  be  regarded  as  particularly  suspicious. 


THE  SOURCES  AND  NATURE  OF  WATER  POLLUTION  AND 

INFECTION 

A  distinction  is  drawn  between  a  polluted  and  an  infected  water. 
A  polluted  water  is  one  that  contains  organic  matter  and  the  products 
of  decay,  either  of  vegetable  or  animal  origin.  An  infected  water  is 
one  that  contains  the  specific  parasites  causing  disease.  A  polluted 
water  may  not  be  particularly  harmful  to  health ;  it  is  always  suspicious. 
That  is,  a  polluted  water  is  not  necessarily  infective;  an  infected  water 
is  practically  always  polluted.  Practically  all  surface  waters  are  pol- 
luted; ground  waters  usually  show  evidence  of  past  pollution;  that  is, 
they  contain  inorganic  salts  in  solution  resulting  from  the  mineraliza- 
tion of  organic  matter. 


WATEE  POLLUTION  AND  INFECTION  817 

The  greatest  hazard  to  man  is  found  in  a  water  polluted  with  the 
discharges  from  the  human  body — feces,  urine,  and  sputum.  There 
is  comparatively  little  danger  from  water  containing  the  wastes  of  other 
animal  life,  for  the  reason  that  few  of  the  infections  of  the  lower  ani- 
mals are  thus  transmissible  to  man.  There  is  still  less  danger  in  water 
contaminated  with  organic  matter  of  plant  origin.  Water  containing 
inorganic  substances  in  solution  plays  a  relatively  minor  role,  as  far  as 
health  is  concerned. 

From  a  sanitary  standpoint,  then,  it  is  the  wastes  of  human  life  that 
concern  us  especially.  These  may  enter  a  surface  water  directly  from 
overhanging  privies,  or  from  sewers,  or  from  washings  of  the  land. 
Ground  water  becomes  polluted  in  ways  already  discussed. 

The  prevention  of  the  pollution  of  our  streams,  lakes,  ponds,  and 
other  surface  supplies  is  an  important  sanitary  problem  with  a  large 
economic  side.  As  far  as  streams  and  large  lakes  are  concerned,  the 
most  dangerous  infection  is  that  which  is  nearby — ^that  is,  that  which 
is  quickly  transferred  in  a  fresh  and  virulent  form.  Distant  infection 
is  much  less  dangerous.  Cities  taking  water  from  an  average  stream 
should  prevent  the  access  of  direct  pollution  for  at  least  50  miles,  or 
better  100  miles,  above  the  intake.  Partial  protection  may  also  be  accom- 
plished by  requiring  sewage  disposal  works  for  all  towns  and  settlements, 
and  abolishing  all  overhanging  privies  upon  the  river  and  its  tributaries. 
A  sanitary  inspector  could  cover  a  large  area  for  this  purpose.  When 
these  measures  are  not  feasible,  intercepting  sewers  may  be  built,  as 
on  the  Schuylkill  at  Philadelphia.  Canals  that  parallel  a  river,  as  the 
one  upon  the  bank  of  the  Potomac,  may  receive  the  sewage  and  surface 
drainage  and  thus  protect  the  stream.  It  is  compt.ratively  easier  to 
guard  smaller  lakes  and  ponds  and  impounding  reservoirs. 

Simple  Tests  to  Determine  Sources  of  Pollution, — Sources  of  pollution 
and  possibly  of  infection  may  often  be  determined  by  simple  tests  which 
may  be  carried  out  by  a  layman.  These  tests  afford  valuable  information 
and  consist  in  the  addition  of  some  chemical  substance  to  the  source 
from  which  pollution  is  possible  and  then  determining  whether  the  same 
reappears  in  the  water  supply.  For  this  purpose  a  large  number  of 
substances  that  may  be  readily  recognized  by  their  taste,  odor,  or  ap- 
pearance may  be  used,  such  as  coal  oil,  carbolic  acid,  fluorescin,  and  com- 
mon salt.  Coal  oil  poured  near  the  ground  of  an  artesian  well  is  an 
easy  and  convincing  method  of  establishing  the  presence  of  defective 
piping  and  surface  or  sub-soil  contamination.  Nordlinger  recommends 
for  this  purpose  saprol,  which  tastes  like  naphtha  and  is  so  penetrating 
that  its  odor  may  be  readily  recognized  in  proportions  of  1-1,000,000  or 
by  taste  in  solutions  of  1-3,000,000.  Trillat  experimented  with  a  large 
number  of  dyes  and  finds  that  fluorescin  dissolved  in  alcohol  and  diluted 
with  5  per  cent,  ammonia  solution  can  be  detected  by  a  fluoroscope  in 


818  GENERAL  CONSIDERATIOISrS 

proportions  of  1-3,000,000,000.  The  fluoroscope  is  a  tube  of  dear  glass 
three  or  four  feet  long  and  one-half  inch  in  diameter,  closed  at  one  end 
with  a  rubber  cork.  In  such  a  tube  natural  waters  have  a  somber  blue 
color  which  changes  to  a  clear  green  if  fluorescin  is  present.  Fluorescin 
can  be  detected  by  the  unaided  eye  in  dilutions  of  0.635  part  per  million. 
This  dye  possesses  the  evident  advantage  of  not  being  precipitated  by 
the  soil  ingredients,  a  reaction  that  readily  occurs  with  most  aniline  dyes 
brought  in  contact  with  calcareous  solutions.  Salts  of  lithium  are  some- 
times used,  for  they  may  be  detected  in  the  minutest  traces  if  the  water 
is  examined  by  the  aid  of  a  spectroscope. 

The  conclusion  must  not  be  drawn  that  because  these  soluble  salts 
reappear  in  the  water  microorganisms  and  dangerous  pollution  would 
likewise  find  its  way  through  the  soil  for  an  equal  distance,  for  the 
soil  has  well-known  filtering  pcrwer  when  free  from  fissures  or  actual 
channels  and  is  capable  of  removing  bacteria  and  oxidizing  large  quan- 
tities of  organic  matter.  However,  these  methods  are  of  service  in  indi- 
cating the  possibility  of  danger  under  certain  circumstances  and  are 
particularly  useful  in  discovering  sources  of  pollution  near  wells  or  in 
limestone  formations. 

Massive  cultures  of  prodigiosus,  pyocyaneus,  fluorescens,  yeasts,  and 
other  microorganisms  if  not  normally  present  in  the  water  under  exam- 
ination may  be  used  to  detect  the  possibility  of  pollution.  The  cultures 
are  poured  upon  the  ground  or  into  suspicious  places  and  the  water 
tested  at  varying  intervals  to  determine  whether  they  reach  the  supply. 
Careful  controls  must  be  made  beforehand  to  assure  the  absence  of  the 
particular  organism  used. 

The  Interstate  Pollution  of  Streams. — Sanitarians  have  maintained 
for  years  that  no  community  or  individual  has  a  right  to  pollute  streams 
used  for  public  water  supplies,  any  more  than  a  man  has  a  right  to 
poison  his  neighbor's  well.  The  legal  aspects  of  water  pollution  have 
been  carefully  considered  by  Dr.  J.  L.  Leal.  England  enjoyed  the  ben- 
efit of  a  Rivers  Pollution  Commission  as  early  as  1855,  in  order  to  pre- 
vent, remedy,  and  remove  the  danger  of  polluted  water  supplies.  This 
commission  adopted  a  comprehensive  system  for  the  disposal  of  sewage 
and  for  water  purification,  the  fruits  of  which  England  is  enjoying 
to-day.  This  country  has  no  law  regarding  the  interstate  pollution  of 
streams,  and  with  our  growing  population  and  increasing  amount  of 
pollution  this  is  becoming  a  live  and  pressing  sanitary  question.  After 
the  Chicago  drainage  canal  was  opened  the  city  of  St.  Louis  (state 
of  Missouri)  sued  the  city  of  Chicago  (state  of  Illinois)  through  the 
federal  courts,  asking  an  injunction  against  the  pollution  of  the  Missis- 
sippi River,  from  which  St.  Louis  draws  its  drinking  supply.  The  testi- 
mony occupied  many  weeks,  and  in  published  form  takes  up  many  vol- 
umes.   The  verdict  was  "no  cause  for  action,"  or  "not  guilty,"  that  is,  it 


WATER  POLLUTION  AND  IXFECTION"  819 

was  not  proven  that  typhoid  bacilli  or  other  organisms  dangerous  to 
health  reached  St.  Louis  from  Chicago. 

The  principles  of  common  law  as  to  interstate  waters  have  been  ap- 
preciated by  some  of  the  nations  of  Europe.  Thus,  the  inhabitants 
of  a  town  in  Belgium  suffered  from  the  effects  of  a  river  polluted  by 
the  French,  and  the  French  government  not  only  compelled  the  offend- 
ing city  to  dispose  of  its  sewage  by  irrigation,  but  granted  a  subsidy 
for  this  purpose.  In  some  of  our  more  progressive  states,  as,  for  ex- 
ample, Massachusetts,  Pennsylvania,  Connecticut,  Minnesota,  New 
Hampshire,  New  Jersey,  New  York,  Vermont,  and  others,  the  State 
Board  of  Health  is  given  control  over  the  pollution  of  streams  within 
the  borders  of  the  state. 

Speaking  generally,  jurisdiction  over  the  pollution  of  waters  in  the 
United  States  is  confined  to  the  several  states.  There  is  no  provision 
in  the  Constitution  which  gives  to  Congress  authority  in  the  premises. 
Hence,  by  the  familiar  principle  in  our  Constitution  that  the  several 
states  retain  full  sovereign  power,  except  so  far  as  such  powers  are 
restricted  by  the  national  constitution  or  expressly  delegated  thereby  to 
the  national  government,  the  individual  states  have  full  control  of  this 
subject-^a  subject  with  which  they  are  individually  impotent  to  deal 
and  which  logically  belongs  to  the  federal  government. 

The  Care  of  Catchment  Areas. — "Catchment  area,"  "water-shed," 
"drainage  area,"  and  "catchment  basin"  are  terms  used  to  include  the 
area  immediately  surrounding  a  water  supply  so  situated  that  water 
falling  upon  it  will  be  directed  toward  this  supply.  The  ideal  catchment 
area  is  free  from  human  habitation  and  is  covered  with  forests.  The 
catchment  areas  supplying  impounding  reservoirs  and  the  natural  ponds 
and  lakes  used  as  reservoirs  are  limited  in  area  when  compared,  for 
example,  with  the  catchment  areas  of  the  great  rivers,  from  which  many 
public  water  supplies  are  drawn.  It  is,  therefore,  possible  to  inspect  and 
control  the  former  more  readily  than  the  latter. 

It  is  often  impossible  to  remove  population  from  a  catchment  area, 
and,  in  fact,  it  is  usually  unnecessary  to  do  so.  Very  good  water  may 
be  drawn  from  areas  upon  which  there  is  a  large  population,  when  proper 
and  well-known  precautions  are  taken.  Thus,  there  are  776  people  per 
square  mile  upon  the  Cochituate  catchment  area,  282  upon  the  Sudbury, 
49  upon  the  Wachusett,  furnishing  Boston's  water  supply,  and  59  upon 
the  Croton,  furnishing  New  York's  water  supply. 

The  prolonged  storage  of  the  water  in  large  protected  reservoirs  is  a 
sanitary  safeguard,  and  makes  the  Boston  water  and  the  New  York  water 
safer  than  it  otherwise  would  be.  The  greatest  danger  is  that  some 
polluted  water  will  sometimes  get  by  the  reservoir  or  flow  through  it 
by  some  short  circuit,  as  surface  currents  or  by-passes,  and  so  reach  the 
consumer,  before  it  is  subjected  long  enough  to  full  storage  conditions. 


820  CENERAL  CONSIDER ATTOXS 

The  proper  sanitary  care  of  a  catchment  area  requires,  first  of  all, 
sufficient  laws  granting  suitable  authority,  especially  concerning  the  dis- 
posal of  human  wastes. 

Care  must  also  be  exercised  to  keep  out  manufacturing  wastes  and 
the  surface  washings  that  may  carry  pollution  from  human  sources  or 
undesirable  contamination  from  other  sources.  This  object  may  be  ac- 
complished in  various  ways.  The  city  should  own  the  shores  of  the 
reservoirs  and  also  as  much  of  the  land  along  the  important  streams 
as  is  necessary  to  carry  out  these  objects.  Old  sources  of  pollution  must 
be  removed,  and  new  sources  not  permitted.  Where  the  danger  from 
human  pollution  is  especially  great,  as  around  the  impounding  reservoir 
itself  or  at  nearby  suburban  settlements,  engineering  projects,  some- 
times of  considerable  magnitude,  are  necessary  to  carry  away  the  sewage 
and  the  surface  drainage.  A  strict  patrol  of  the  catchment  area,  in 
order  to  supervise  picnic  and  camping  parties,  the  camps  of  construction 
gangs,  and  other  sources  of  danger,  must  be  exercised.  A  good  man  on 
the  alert  can  patrol  a  large  district,  getting  his  information  through 
various  ways,  and  personally  inspecting  all  suspicious  localities  fre- 
quently. 

In  the  investigation  of  a  stream  and  its  watershed  the  chief  points 
requiring  attention  are  the  relative  proportions  of  the  polluting  mat- 
ter and  the  flow  of  the  river  when  at  its  minimum;  the  general  char- 
acter of  the  stream,  the  rate  of  flow,  and  the  distance  between  the 
source  of  pollution  and  the  intake  of  the  water. 

Many  water  boards,  having  control  of  large  tracts  of  land,  are  plant- 
ing their  catchment  areas  with  trees  with  advantage  and  profit,  for  it  is 
found  that  the  presence  of  trees  adds  to  the  retention  of  water  falling 
as  rain  as  well  as  by  radiation,  and  cooling  the  adjacent  atmosphere,  per- 
haps aiding  condensation  and  rain.  It  prevents  floods,  regulates  and 
helps  to  purify  the  supply,  for  water  ■  draining  through  the  soil  of 
wooded  areas  is  naturally  cleaner  than  that  scouring  the  surface  of 
barren  land. 


CHAPTEE   II 
SANITAEY  ANALYSIS  OF  WATEE 

A  complete  sanitary  analysis  of  water  includes :  (1)  a  physical  exam- 
ination to  determine  color,  turbidity,  odor,  and  taste;  (3)  a  microscopic 
examination  to  determine  the  number  and  character  of  particles  in  sus- 
pension, especially  algae;  (3)  a  cliemical  analysis  to  determine  the  nature 
and  amount  of  chemical  impurities;  (4)  a  bacteriological  examination 
to  estimate  the  number  and  kind  of  bacteria;  (5)  a  sanitary  survey  of 
the  Avatershed,  including  the  methods  of  collecting,  storing,  handling,  and 
distributing  the  water;  and  (6)  clinical  experience,  which,  after  all,  is 
the  final  test,  for  water  may  contain  impurities  that  are  not  recognizable 
by  any  other  method. 

Water  is  particularly  liable  to  contamination  under  prevailing  con- 
ditions and  must,  of  necessity,  demand  increasing  watchfulness  and  a 
continual  readjustment  of  restrictions  governing  its  use.  Water  may 
contain  impurities  beyond  the  power  of  science  to  disclose.  Thus,  the 
water  supply  of  Vienna  from  the  famous  Kaiserbrunnen  is  particularly 
pure,  as  determined  by  laboratory  analysis.  Nevertheless,  this  water 
supply  is  said  to  be  responsible  for  a  great  increase  in  the  number  of 
cases  of  goiter  which  has  been  observed  in  Vienna  since  its  introduc- 
tion. 

The  fact  that  water  is  the  most  universal  solvent  known  is  not  to 
be  neglected.  The  water  we  drink  has  come  in  contact  with  the  earth 
and  many  other  substances.  It  dissolves  many  organic  and  many  in- 
organic impurities,  few  of  which  can  be  detected  in  the  laboratory  by 
the  routine  methods  used.  The  influence  of  many  of  these  substances 
upon  health  is  unknown.  Exceedingly  small  amounts  of  poisonous  sub- 
stances in  water  may  act  injuriously  when  we  recall  how  much  water 
is  daily  taken.  All  these  facts  should  make  us  cautious  before  we  give 
a  water  supply  a  clean  bill  of  health,  and  communities  will  find  it  pays 
in  the  end  to  go.  to  great  expense  to  improve  this  important  article 
of  daily  use. 

Standard  Methods. — The  advantages  of  using  a  standard  method  are 
self-evident;  it  at  least  gives  results  that  are  fairly  comparable  with  the 
work  of  others.  The  standard  methods  for  water  analysis  have  been 
carefully  considered  by  a  competent  committee  of  the  American  Public 
Health  Association.     The  first  report  was  published  in  the  Journal  of 

821 


832  SAXITAKV   ANALYSIS  OK  WA'I'KK 

InfectiotUi  Diseases,  Su})])leni('i)t  Xo.  ],  May,  1905.^  Amendments  and 
improvements  to  the  method  are  published  from  time  to  time.  For  any- 
one not  having  special  skill  in  chemical  analysis  or  bacteriological  tech- 
nic  it  is  advisable  to  adhere  closely  to  the  standard  procedures.  Any 
deviation  from  these  methods  should  always  be  noted  in  published  re- 
ports. Because  a  method  is  "standard"  does  not  mean  that  it  has  a 
fixed  and  permanent  value  as  a  model  to  be  blindly  followed  under  all 
circumstances.  Standard  methods  are  established  by  common  consent 
as  the  rule  to  be  followed  under  ordinary  circumstances,  especially  for 
routine  work  and  by  those  who  are  not  especially  skilled  in  laboratory 
technic.  For  reasons  that  seem  self-evident,  it  is  of  special  importance 
to  follow  the  standard  methods  for  bacterial  counts.^ 

Our  standards  by  which  the  purity  of  water  is  judged  are  constantly 
rising.  There  is  no  doubt  that  many  waters  now  considered  safe  and 
wholesome  will  not  be  acceptable  in  the  future. 

Collection  of  the  Sample. — For  a  complete  physical,  chemical,  and 
microscopical  analysis  of  water  one  gallon  is  necessary.  If  the  sample  has 
been  collected  in  a  sterile  container  with  bacterial  precautions,  the  same 
sample  may  serve  for  the  bacteriological  examination.  Usually  the  bac- 
teriological samples  are  collected  separately  in  special  bottles  holding 
four  ounces. 

The  bottles  should  be  of  hard,  clear  white  glass  and  have  a  glass 
stopper.  They  should  be  chemically  clean  and  sterilized  at  160°  C.  for 
1  hour,  or  in  the  autoclave  at  115°  C.  for  15  minutes.  For  transpor- 
tation they  may  be  wrapped  in  sterile  cloth  or  paper,  but,  better,  the 
neck  may  be  covered  with  tinfoil  and  the  bottle  placed  in  a  tin  box. 
When  bacterial  samples  must  of  necessity  stand  12  hours  before  jjlating, 
bottles  holding  more  than  4  ounces  should  be  used.  Cork  stoppers  should 
never  be  permitted,  except  when  physical  or  microscopical  examination 
only  is  to  be  made.  Earthen  jugs  and  metal  containers  are  entirely 
unsuited. 

Generally  speaking,  the  shorter  the  time  elapsing  between  the  collec- 
tion and  analysis,  the  more  reliable  will  be  the  analytical  results.  If  too 
long  a  time  intervenes,  it  affects  especially  the  bacterial  tests,  for  bac- 
teria multiply  enormously  when  water  is  kept  in  a  bottle  at  ordinary  tem- 
perature. The  oxygen  consumed,  oxygen  required,  and  nitrites  are  also 
materially  affected  by  comparatively  short  delay. 

In  general,  water  must  be  analyzed  as  soon  as  possible  after  sampling. 
The  following  are  the  maximum  times  allowed  by  the  Standard  Methods 
of  the  American  Public  Health  Association: 

^  The  second  edition  can  be  obtained  from  the  secretary  of  the  association, 
289  Fourth  Avenue,  New  York  City. 

^  In  the  methods  for  water  analysis  described  in  this  book  the  standard 
methods  have  been  closely  followed,  and  due  acknowledgment  is  here  given  to 
the  splendid  and  self-eifacing  work  of  the  committee  tliat  devised  them. 


ODORS  AI^D  TASTE  823 

Physical  and  Chemical  Analysis: 

Ground  waters 72  hours 

Fairly  pure  surface  waters 48     " 

Polluted  surface  waters 12     " 

Sewage  effluence 6     " 

Raw  sewages 6     " 

Microscopic  Examination: 

Ground  waters 72     " 

Fairly  pure  surface  waters 24     " 

Waters  containing  fragile  organisms . .  Immediate  examination 

should  be  made  in  situ 
if  practicable. 
In  bacteriological  Examinations,  samples 

at  less  than  10°  C 6  hours 

Care  should  be  taken  to  secure  a  sample  which  is  thoroughly  repre- 
sentative of  the  water  to  be  analyzed.  A  pump  should  be  operated  five 
minutes,  or  water  faucet  allowed  to  run  several  minutes,  before  the 
bottle  is  filled.  In  collecting  samples  of  surface  waters  the  specimen 
should  not  be  obtained  too  near  the  bank  of  the  stream  or  pond.  A  note 
should  be  made  as  to  whether  the  specimen  is  collected  from  the  surface 
or  at  what  depth  under  the  surface  it  is  taken.  It  is  always  advisable 
to  take  the  temperature  of  the  water  at  the  time  of  collection. 


ODORS  AND  TASTE 

The  purest  water  is  absolutely  devoid  of  taste  and  odor,  but  it  is 
also  insipid.  If  such  water  is  aerated  by  agitation  or  by  filtration 
through  a  porous  air-containing  substance,  it  becomes  sparkling  and 
agreeable.  The  taste  is  imparted  to  most  waters  by  the  mineral  matter 
as  well  as  the  gases  held  in  solution,  hence  the  flat  insipid  taste  of  dis- 
tilled water.  After  a  person  becomes  accustomed  to  the  taste  of  a  par- 
ticular water  another  does  not  appeal  to  him  and  does  not  satisfy  his 
thirst  to  so  great  an  extent.  Once  having  been  accustomed  to  a  moder- 
ately hard  water,  a  soft  water  is  very  flat  and  tastes  much  like  distilled 
or  rain  water. 

Odors  in  waters  are  objectionable,  rather  than  detrimental  to  health. 
As  a  rule,  the  most  objectionable  odors  develop  in  surface  waters  and 
are  caused  by  the  growth  of  algae,  diatoms,  protozoa,  and  other  micro- 
scopic beings.  The  earthy  odor  of  some  ground  waters  is  due  to  sub- 
stances taken  up  during  the  passage  of  the  water  through  the  soil.  When 
a  well-water  becomes  ofFensive  it  is  evidence  of  stagnation  at  the  bottom 
of  the  well  or  the  presence  of  dead  animals.  In  the  case  of  deep  wells 
hydrogen  sulphid  and  other  inorganic  compounds  may  impart  odors  to 
the  water.  The  odors  and  tastes  which  develop  in  impounding  reser- 
voirs from  stagnation  and  putrefaction  of  the  organic  matter  have  been 
discussed  on  page  805. 


ALGAE:    i,  UR0GLENA-X300       2.  SPIR03YRA-X  500,    3.  RESTING  S  PORES  OF  Spi  ROG  r'RA-X  500; 
4,  ChLAMVOOMONAS    showing   resting  condition  and  reproductive;    BODii:  3   -    >     lOOO 


Fig.  103. — Algae  Commonly  Found  in  Water.  [Year  Book,  U.  S.  Dept.  of  Age.,  1902.) 

824 


ALGAE:  i,  Clathrocystis- xsoO;      2,  Anabacna-x  500, 

3     OSClLLATORIA-X    500:  4  ,  ASTER  lONE  LLA-X  500 

5     NaViCULA   showing 'STRUCTURE  OF  DIATOM  -X  500 


Fig.  104. — Algae  Commonly  Found  in  Water.    (Yeah  Book,  U.  S.  Dept.  of  Agk.,  1902. 

825 


826  SANITARY  ANALYSTS  OF  WATER 

On  the  whole,  the  waters  of  natural  lakes  and  ponds  are  less  subject 
to  objectionable  odors  and  tastes  than  are  the  waters  of  artificial  reser- 
voirs, and  putrefaction  is  less  troublesome,  but  the  difference  is  one  of 
degree,  not  of  kind. 

The  power  of  water  to  dissolve  or  absorl)  gases  and  odors  is  an  im- 
portant one,  and  explains  how  water  may  become  "contaminated"  by 
mere  exposure  to  an  impure  atmosphere,  as  when  an  uncovered  cistern 
is  placed  in  a  water-closet  or  when  an  overflow  pipe  is  directly  connected 
with  a  drain. 

Method  of  Determining  Odor. — The  odor  of  the  water  should  be 
observed  both  at  room  temperature  and  just  below  the  boiling  point. 
Odors  may  be  detected  at  room  temperature  (20°  C.)  by  shaking  a 
sample  violently  in  a  gallon  collecting  bottle  when  it  is  half  or  two- 
thirds  full;  or  by  heating  about  150  c.  c.  in  a  tall  beaker  without  a  lip 

and  covered  with  a  well-fitting 
watch  glass.  In  either  case  care 
should  be  taken  to  observe  the  char- 
acter of  the  odor  the  instant  the  re- 
ceptacle is  uncovered.  The  kind  of 
Fig.    105. — The    Oil    Droplets    in    a  ^  i  t  ^        -,  -i     ^ 

Diatom.  o*^^^  observed  may  be  described  as 

vegetable,  aromatic,  grassy,  fishy, 
earthy,  moldy,  musty,  disagreeable,  peaty,  sweetish,  etc.,  and  the  intensity 
by  such  terms  as  very  faint,  distinct,  decided,  or  very  strong. 

The  odors  and  tastes  in  water  caused  by  microscopic  organisms  de- 
serve special  consideration,  because  they  are  common  faults  in  water 
stored  in  open  artificial  reservoirs  of  all  kinds.  Certain  organisms  can 
be  distinguished  by  their  odor,  as,  for  example,  the  "fishy'^  odor  of 
Uroglena,  which  is  a  protozoon  and  classed  with  the  Infusoria;  the 
"aromatic"  or  "rose  geranium"  odor  of  Asterionella,  which  belongs  to 
the  Diatomaceae;  and  the  "pig-pen"  odor  of  Anaboena,  which  is  one  of 
the  blue-green  algae. ^  These  microscopic  organisms  mostly  grow  near 
the  surface  and  require  sunlight  for  their  development;  hence,  odors 
produced  by  them  never  occur  in  covered  reservoirs  or  in  waters  kept 
in  the  dark. 

Calkins  has  shown  that  the  odors  caused  by  the  undecomposed  micro- 
scopic organisms  are  due  to  compounds  of  the  nature  of  essential  oils, 
and  Whipple  points  out  that  the  amount  of  such  oil  produced  by  an 
abundant  growth  of  the  organisms  is  quite  sufficient  to  account  for  the 
effect  observed.  He  notes  for  comparison  that  oil  of  peppermint  can  be 
recognized  when  diluted  with  water  in  the  proportion  of  one  part  of 
oil  to  fifty  million  parts  of  water,  and  that  when  Asterionella  is  present 
to  the  extent  of  50,000  organisms  per  c.  c.  the  dilution  of  its  oil  is 

'  See  also  Whipple,  "Microscopy  of  Drinking  Water,"  John  Wiley  &  Sons, 
1914. 


ODOES  AXD  TASTE-  827 

]'ji  the  })roportion  of  about  one  part  to  two  million  parts  of  water.  Wliip- 
jjle  further  suggests  that  the  flow  of  water  through  pipes  may  cause  dis- 
integration of  organisms  with  liberation  of  the  odor-producing  oil,  hence 
the  odor  at  the  tap  may  be  greater  than  at  the  intake. 

The  Algae  responsible  for  the  vile  tastes  and  odors  in  water  do  not 
depend  upon  organic  matter  or  the  bodies  of  other  organisms  for  their 
food  supply.  They  require  only  carbonic  acid  and  the  nitrogen  and 
mineral  matters  always  present  in  the  water  and  in  the  air,  and  the 
sunshine  for  their  growth.  In  other  words,  they  have  properties  com- 
parable in  many  respects  to  the  higher  orders  of  chlorophyll-containing 
vegetation. 

There  are  very  many  kinds  of  algae,  and  they  differ  greatly  in  their 
odor-producing  powers.  Practically  all  American  impounding  reservoir 
waters  suffer  from  them,  but  some  far  more  than  others.  English  reser- 
voirs seem  to  be  comparatively  free  from  this  nuisance,  probably  because 
of  the  lower  temperatures  of  the  surface  waters.  There  is  an  average 
difference  of  at  least  10°  F.  between  the  surface  temperatures  of  English 
and  American  reservoirs. 

A  certain  degree  of  quiet  and  repose  is  necessary  for  the  develop- 
ment of  a  large  growth  of  algae ;  that  is  why  they  never  develop  to  any 
extent  in  rivers  and  flowing  water.  Wave  action  from  wand  also  pre- 
vents growth,  and  this  seems  to  be  the  only  reason  why  large  lakes  and 
reservoirs  are  less  troubled  by  them  than  smaller  ones. 

In  most  American  impounding  reservoirs  the  water  is  drawn  from 
near  the  surface  layer,  so  as  to' avoid  the  odors  and  tastes  of  putrefaction 
in  the  bottom  water,  but  it  sometimes  happens  that  the  surface  water  is 
the  more  objectionable. 

Prevention  and  Removal  of  Tastes  and  Odors. — The  natural  flow  of 
water  in  the  bed  of  a  mountain  stream  over  stones  and  ledges  aerates 
it  very  well.  This  is  nature's  method  of  removing  undesirable  tastes 
and  odors.  Aeration  may  also  be  accomplished  by  bringing  the  water 
in  contact  with  the  air  by  devices  such  as  fountains,  waterfalls,  etc. 
Such  aeration  always  reduces,  and  sometimes  removes,  tastes  and  odors 
from  the  waters  of  reservoirs  and  small  lakes,  whether  resulting  from 
putrefaction  in  the  stagnant  bottom  water  or  from  growths  of  organ- 
isms in  the  surface  water. 

In  general  it  may  be  stated  that  filtration  alone  is  not  efficient  in 
removing  tastes  and  odors;  however,  slow  sand  filtration  has  consid- 
erable power  of  reducing,  and  in  some  cases  of  removing,  tastes  and 
odors,  but  it  cannot  be  depended  upon  when  the  raw  water  is  very 
bad. 

Intermittent  filtration  is  particularly  successful  in  removing  tastes 
and  odors.  It  is  successful  because  it  brings  the  organic  matter  in  con- 
tact with  more  air  and  in  more  intimate  contact  with  air,  and  for  a 


828  SANITAEY  ANALYSTS  OF  WATER 

longer  time  in  the  pores  of  the  sand,  than  can  be  securef]  in  any  other 
way. 

It  is  practically  impossible  to  prevent  the  seeding  of  reservoirs  and 
ponds  with  algae  and  other  organisms  responsible  for  tlie  objoctionuble 
odors.  The  growth  may  be  checked  and  the  odors  temporarily  con- 
trolled by  the  nse  of  copper  sulphate  (see  page  909). 

If  a  well  become  stagnant  at  the  bottom,  and  thus  develops  vile 
odors  from  putrefying  organic  matter,  the  trouble  may  be  corref;ted  by 
lowering  the  pnmp  to  near  the  bottom  so  as  to  prevent  stagnation,  or  by 
filling  up  all  "unnecessary  space  with  clean  gravel  and  sand. 


COLOR 

Pure  water,  when  viewed  in  small  quantities,  appears  to  be  perfectly 
colorless,  but,  when  viewed  in  bulk,  as  in  the  white-tiled  baths  at  Bux- 
ton, and  in  certain  Swiss  lakes,  it  is  seen  to  possess  a  beautiful  greenish- 
blue  tint.  A  very  small  amount  of  suspended  or  dissolved  imjDurity 
is  sufficient  to  obscure  this  color. 

Impure  waters  almost  invariably  exhibit  a  color  varying  from  green 
to  yellow  and  brown,  when  examined  through  a  depth  of  tAvo  feet  in 
suitable  tubes.  It  does  not,  however,  follow  that  a  colored  water  is, 
therefore,  polluted  or  infected. 

Color  in  surface  water  is  usually  of  vegetable  origin;  animal  matter 
contributes  but  little  color.  The  coloring  matter  is  extracted  largely 
from  dead  leaves,  bark,  and  roots,  from  soil,  and  from  peat.  It  seems 
to  be  the  same  material  as  the  coloring  matter  of  tea,  and  it  is  cer- 
tainly harmless,  but  it  makes  the  water  less  pleasing  in  appearance,  and 
great  efforts  have  rightly  been  made  to  prevent  it  and  to  remove  it. 
Water  from  swamps  is  usually  highly  colored,  the  degree  of  color  de- 
pending upon  the  length  of  exposure. 

Ground  waters  are  usually  colorless.  If  the  water  contains  iron  it 
will  be  perfectly  clear  on  coming  from  the  ground,  but  will  soon  turn 
a  rusty  yellow  color.  This  is  caused  by  the  oxidation  of  the  soluble  fer- 
rous salts  to  insoluble  ferric  salts. 

Color  in  water  should  be  distinguished  from  turbidity.  True  color 
is  due  to  dissolved  impurities,  turbidity  to  substances  in  suspension.  The 
"apparent  color"  is  the  color  of  the  original  sample,  due  to  both  dis- 
solved and  suspended  matter. 

The  prevention  of  color  in  surface  waters  consists  in  draining  swamps. 
Thus,  in  the  catchment  areas  of  the  various  reservoirs  supplying  Bos- 
ton thousands  of  acres  of  swampy  land  have  been  drained  for  the  pur- 
pose of  reducing  the  color  of  the  supplies,  and  with  good  results. 

A  colored  water  may  be  bleached  by  exposure  to  sunlight  and  air. 


TUKBIDITY  829 

but  the  bleaching  of  the  water  in  reservoirs  requires  great  storage 
capacity,  and  the  drainage  of  swamps  is  likewise  very  expensive.  Ozone 
applied  in  large  amounts  also  destroys  color,  and  the  only  objection  to 
its  use  is  the  cost.  Color  may  be  removed  to  a  considerable  extent  by 
simple  filtration  through  sand.  If  the  coloring  matter  is  first  rendered 
insoluble  by  the  use  of  coagulants  (sulphate  of  alumina),  it  is  readily 
removed  by  filtration.^  Color  is  thus  successfully  removed  from  the 
waters  used  by  Norfolk,  Va. ;  Charleston,  S.  C,  and  Watertown,  N.  Y. 
Sulphate  of  iron  is  less  satisfactory  as  a  coagulant  than  sulphate  of 
alumina  for  the  removal  of  color. 

Method  for  Estimating  Color. — Turbid  waters  should  always  be  fil- 
tered before  the  color  observations  are  made.  The  intensity  of  color 
may  be  determined  by  comparing  with  a  standard  platinum-cobalt  solu- 
tion; the  tint  or  shade  may  be  determined  by  comparison  with  the 
standard  color  disks  of  a  Lovibond  tintometer, 

Platinum-Cobalt  Standard. — The  standard  solution,  which  has  a 
color  of  500,  is  prepared  as  follows : 

Dissolve  1.346  grams  of  potassium  platinic  chlorid  (PtCl43KCl) 
containing  0.5  gram  platinum,  and  one  gram  crystallized  cobalt  chlorid 
(C0CI26H2O)  containing  0.25  gram  of  cobalt  in  water,  with  100  c.  c. 
concentrated  hydrochloric  acid,  and  make  up  to  one  liter  with  distilled 
water. 

By  diluting  this  solution  with  distilled  water  to  the  100-c.  c.  gradu- 
ation mark  on  the  Nessler  tubes,  standards  are  prepared  having  colors 
of  0,  5,  10,  15,  20,  25,  30,  35,  40,  50,  60,  and  70.  These  should  be 
kept  in  ISTessler  tubes  of  such  diameter  that  the  100-c.  c.  graduation 
mark  is  between  20  and  25  cm.  above  the  bottom,  and  is  uniform  for 
all  tubes.    They  should  be  protected  from  dust  when  not  in  use. 

Procedure. — The  color  of  a  sample  is  observed  by  filling  a  standard 
ISTessler  tube  to  the  graduation  mark  with  the  water  to  be  examined,  to 
a  depth  equal  to  that  of  the  standards,  and  by  comparing  it  with  the 
standards.  The  observation  should  be  made  by  looking  vertically  down- 
ward through  the  tubes  upon  a  white  surface  placed  at  such  an  angle 
that  light  is  reflected  upward  through  the  column  of  liquid. 

Waters  that  have  a  color  darker  than  70  should  be  diluted  before 
making  the  comparison,  in.  order  that  no  difficulties  may  be  encountered 
in  matching  hues. 

TURBIDITY 

Practically  turbidity  is  synonymous  with  muddiness.  The  turbidity 
of  surface  waters  is  usually  due  to  clay  or  silt,  also  to  finely  divided 
organic  matter,  microscopic  organisms,  and  a  great  variety  of  objects. 

^For  the  reactions  with  Alum  see  page  907. 


830  SANITARY  ANALYSIS  OF  WATER 

Turbidity  represents  the  amount  of  foreign  substances  in  suspeiision  ; 
it  is  frequently,  though  incorrectly,  spoken  of  as  color.  In  a  general 
way  turbid  waters  exist  in  those  regions  where  color  is  not  found;  the 
former  represents  the  washings  of  a  readily  eroded  drainage  basin,  the 
latter  is  mostly  extracted  from  the  decaying  vegetation  of  swamps. 

Pure  water  is  clear  and  sparkling,  in  proportion  to  the  amount  of 
dissolved  oxygen  and  carbonic  acid.  While  brilliancy  and  clearness  do 
not  mean  purity,  on  the  other  hand  turbid  waters  are  not  necessarily 
dangerous.  A  community  for  years  may  drink  and  seem  satisfied  with 
a  turbid  water  that  is  little  less  than  liquid  mud.  This  was  the  case 
with  Washington  and  the  Potomac  water,  St.  Louis  and  the  Mississippi, 
and  many  other  cities.  When,  however,  such  a  city  once  appreciates 
the  beautiful  appearance  of  a  clean  water,  they  complain  if  the  turbid- 
ity reaches  the  point  of  a  faint  opalescence.  The  turbidity  question  is 
practically  limited  to  river  waters.  Ground  waters  should  never  be 
turbid,  and,  if  so,  should  at  once  excite  suspicion.  Some  ground  waters 
become  more  or  less  turbid  through  the  precipitation  of  iron. 

-All  river  waters  are  more  or  less  turbid,  but  the  differences  are 
very  great  indeed.  The  amount  of  turbidity  depends  largely  upon  the 
character  of  the  catchment  areas.  In  general,  rivers  draining  the  large 
areas  of  our  North  and  East,  covered  with  glacial  drift  of  a  sandy 
character,  are  but  little  subject  to  turbidity.  Thus,  on  an  average,  the 
Merrimac  and  Connecticut  Rivers  do  not  carry  more  than  10  parts  per 
million  of  suspended  matter.  In  that  part  of  our  country  which  is  not 
glaciated,  and  this  includes  the  lower  Susquehanna  basin,  much  of  the 
Ohio  basin,  and  the  Missouri  basin,  and  all  to  the  south  of  them,  tur- 
bidity is  often  present  in  large  amounts,  and  consists  largely  of  clay 
in  extremely  fine  particles.  The  water  often  runs  turbid  in  these  streams 
continuously  for  weeks  and  even  months  at  a  time.  The  Missouri  River 
carries  the  largest  amount  of  sediment  of  any  of  our  rivers  largely 
used  for  water  supply.  The  annual  average  runs  as  high  as  1,200  or 
1,500  parts  of  sandy  matter  per  million.  In  winter  it  falls  to  200  parts 
or  less,  while  in  midsummer  it  rises  for  weeks  and  even  months  to  5,000 
parts  or  more. 

If  the  turbidity  is  sufficiently  coarse-grained  it  may  be  removed  by 
sand  filtration  without  previous  chemical  treatment.  Very  turbid  waters 
can  be  cleared,  in  part,  in  settling  basins;  this  lightens  the  work  of 
the  filters  and  reduces  the  cost.  Scrubbers,  which  are  preliminary  rough 
filters,  may  also  be  used  to  protect  the  sand  filters.  In  many  instances 
the  individual  particles  of  clay  which  make  up  the  turbidity  are  much 
smaller  than  the  bacteria.  They  will  not  settle  out,  even  after  prolonged 
storage,  and  they  cannot  always  be  removed  by  filtration  alone.  There 
is  only  one  known  way  of  removing  such  turbidity,  and  that  is  by  coagu- 
lation or  chemical  precipitation.     The  substances  most  commonly  used 


REACTION  831 

for  this  purpose  are :  aluminium  sulphate,  alum,  or  sulphate  of  iron 
(see  page  906). 

With  reference  to  the  influence  of  the  suspended  matter  upon  health 
we  find  some  conflict  of  opinion.  Kober  states  that  water  containing  50 
parts  per  100,000  or  30  grains  of  solid  matter  per  gallon  is  unfit  for 
drinking  purposes,  on  account  of  its  irritating  efi'ects  upon  the  gastro- 
intestinal tract.  Apart  from  this,  turbidity  appears  to  have  no  special 
sanitary  significance. 

Methods  for  Estimating  Turbidity. — There  are  three  methods  by 
which  the  degree  of  turbidity  may  be  determined:  (1)  the  platinum 
wire  method,  which  consists  of  determining  the  depth  of  water  through 
which  a  platinum  wire  of  standard  diameter  may  be  seen;  (2)  com- 
parison with  waters  of  standard  turbidity,  made  by  adding  1  gram  of 
finely  powdered  diatomaceous  earth  to  1  liter  of  distilled  water;  this  is 
known  as  the  silica  standard;  and  (3)  the  amount  of  suspended  par- 
ticles in  water  may  be  determined  in  special  instruments  known  as 
turbidimeters  or  diaphanometers.  These  instruments  consist  of  a  grad- 
uated glass  tube  with  a  flat  polished  bottom,  inclosed  in  a  metal  case. 
This  is  held  Over  an  English  standard  candle,  and  so  arranged  that  one 
may  look  vertically  down  through  the  tube  and  see  the  image  of  the 
candle.  The  observation  is  made  by  pouring  the  sample  of  water  into 
the  tube  until  the  image  of  the  candle  Just  disappears  from  view.  The 
graduations  on  the  tube  correspond  to  turbidities  produced  in  distilled 
water  by  certain  numbers  of  parts  per  million  of  the  silica  standard. 

The  standard  of  turbidity  adopted  by  the  United  States  Geological 
Survey  ^  consists  of  a  water  which  contains  100  parts  of  silica  per  mil- 
lion, in  such  a  state  of  fineness  that  a  bright  platinum  wire  1  millimeter 
in  diameter  can  just  be  seen  when  the  center  of  the  wire  is  100  milli- 
meters below  the  surface  of  the  water  and  the  eye  of  the  observer  is  1.3 
meters  above  the  wire,  the  observations  being  made  in  the  middle  of  the 
day  in  the  open  air,  but  not  in  sunlight,  and  in  a  vessel  so  large  that  the 
sides  do  not  shut  out  the.  light  so  as  to  influence  the  results.  The  tur- 
bidity of  such  water  is  taken  as  100,  and  all  turbidity  readings,  by  no 
matter  what  method  used,  should  conform  with  this  method. 

Where  only  an  occasional  analysis  is  made  for  general  purposes  it  is 
sufficient  to  record  the  sediment  and  turbidity  as  very  slight,  distinct, 
or  decided. 

REACTION 

The  alkaline  reaction  of  natural  waters  ordinarily  depends  upon  the 
carbonate  and  bicarbonate  of  calcium  and  magnesium.  In  some  waters 
in  the  West  it  also  includes  the  carbonate  of  sodium  and  of  potassium. 

^U.  S.  Geolog.  Survey,  Div.  of  Hydrography,  Circular  No.  8,  1902. 


833  SANITAEY  ANALYSTS  OF  WATEPt 

The  alkalinity  of  water  is  determined  by  titrating  100  c.  c.  of  the  sample 
with  ^  sulphuric  acid,  using  0.5  c.  c.  of  a  solution  of  lacmoid  as  an 
indicator.  The  lacmoid  solution  consists  of  2  grams  in  one  liter  of 
50  per  cent,  alcohol.  The  last  cubic  centimeter  or  two  of  acid  must 
be  added  while  the  sample  is  almost  at  the  boiling  temperature,  and 
the  end  reaction  is  not  read  until  a  drop  of  acid,  striking  the  surface  of 
the  liquid,  sinks  to  the  bottom  of  the  dish  without  producing  a  change 
in  the  uniform  reddish  or  purplish  color  of  the  solution.  Erythrosin 
may  be  used  as  an  indicator  when  it  is  desired  not  to  use  heat.  The 
number  of  cubic  centimeters  of  ^  sulphuric  acid  used,  when  multiplied 
by  ten,  gives  the  number  of  parts  per  million  of  alkalinity  in  terms  of 
calcium  carbonate. 

Under  certain  circumstances  rain  water,  water  from  peat  bogs,  and 
water  from  coal  mines,  tanneries,  etc.,  have  an  acid  reaction.  In  min- 
ing regions  waters  are  frequently  acid  from  high  quantities  not  only 
of  CO2,  but  also  of  sulphuric  acid  and  various  sulphates — ^those  of  iron 
and  aluminium  giving  an  acid  reaction.  When  these  are  present,  the 
total  acidity  is  determined  by  titrating  the  water  in  the  cold  with  a 
standard  sodium  carbonate  solution,  using  phenolphthalein  as  an  indi- 
cator. 

Mine  water  is  that  which  is  constantly  flowing  from  the  coal  and 
surrounding  strata.  It  is  collected  in  ditches  at  one  side  of  the  gang- 
ways and  tunnels,  and  is  allowed  to  flow  to  the  lowest  point  in  the  mine 
or  to  the  foot  of  the  shaft,  from  which  it  is  pumped  to  the  surface. 
Large  quantities  of  this  and  other  water  are  used  to  wash  the  coal.  This 
water  is  acid,  and  it  is  now  well  known,  from  the  researches  of  Dixon, 
Matson,  and  others  in  the  anthracite  coal  regions  of  Pennsylvania,  that 
such  water  has  a  destructive  effect  upon  typhoid,  colon,  and  other  bac- 
teria. The  acidity  of  the  streams  in  Pennsylvania  is  a  large  factor  in 
neutralizing  the  pollution  of  the  water  supplies  of  Philadelphia,  Pitts- 
burgh, Harrisburg,  and  other  cities.  The  rise  and  fall  of  typhoid  fever 
in  the  "south  side"  of  Pittsburgh  has  been  inversely  as  the  acidity  of 
the  Monongahela  Eiver.  The  spent  tan  liquors  from  tanneries  are 
also  acid,  and  are  known  to  exert  a  somewhat  similar  influence  on  sewage 
organisms. 

Eain  water  collected  in  the  vicinity  of  towns  has  usually  a  slight 
acid  reaction  and  acts  upon  lead.  The  free  acid  in  rain  water  is 
apparently  sulphuric,  no  doubt  derived  from  the  sulphur  in  the  coal 
burned. 

Water  from  marshes,  swamps,  and  especially  from  peat  bogs  may 
have  a  markedly  acid  reaction,  especially  in  dry  weather,  when  the 
flow  will  be  comparatively  small.  Heavy  storms  wash  out  the  water 
which  has  long  been  in  contact  with  the  decaying  vegetation.  The  acid- 
ity in  this  case  is  due  to  organic  acids. 


TOTAL  SOLIDS  833 

When  the  collection  of  an  acid  water  cannot  be  avoided,  arrangements 
should  be  made  for  filtering  through  some  material  capable  of  com- 
pletely neutralizing  the  acid,  as  without  some  such  arrangement  the 
consumers  of  the  water  run  the  risk  of  lead  poisoning,  provided  lead 
service  pipes  are  used.  A  river  water  suddenly  turning  acid  in  reaction 
plays  havoc  with  a  slow  sand  filter.  This  has  occurred  in  the  Pitts- 
burgh filter, 

TOTAL  SOLIDS 

The  total  solids  or  residue  on  evaporation  is  obtained  by  evaporat- 
ing a  given  quantity  of  water  to  dryness,  when  a  grayish-white  residue, 
composed  of  mineral  and  some  organic  matter  which  has  been  held  by 
the  water  in  suspension  and  in  solution,  will  be  obtained.  The  amount 
of  this  residue  varies  with  the  character  of  the  water,  and  furnishes  an 
index  of  the  total  quantity  of  foreign  impurities,  and  further  furnishes 
a  rough  index  of  ■  the  relative  quantity  of  inorganic  and  organic  sub- 
stances which  make  up  these  impurities. 

Method. — Place  100  c.  c.  of  the  water  in  a  clean  platinum  dish.  If 
the  water  is  of  high  magnesium  content  add  25  c.  c.  of  ^-jj-  sodium  car- 
bonate solution  to  the  water,  and  correct  for  this  addition  in  the  com- 
putation; evaporate  to  dryness  on  a  water  bath,  and  finish  the  evapora- 
tion for  half  an  hour  or  to  constant  weight  in  a  toluene  oven  at  103°  C. 
ISTow  place  the  platinum  dish  in  a  desiccator  over  sulphuric  acid  until 
cool,  and  weigh.  The  increase  in  weight  gives  the  total  solids,  or  residue 
on  evaporation.  This  weight  in  milligi'ams  multiplied  by  -^^  gives 
parts  per  million ;  where  x  represents  c.  e.  of  sample  used. 

The  platinum  dish  containing  this  residue  is  now  heated  to  a  dull 
red  heat  and  the  platinum  dish  again  weighed.  The  difference  in  weight 
is  called  the  "loss  on  ignition,"  and  the  weight  of  the  substances  remain- 
ing in  the  platinum  dish  is  known  as  the  "fixed  residue."  The  loss  on 
ignition  is  an  index  of  the  amount  of  organic  matter  in  the  water.  A 
portion  of  the  loss,  however,  may  be  due  to  ammonia  or  other  volatile 
compounds  and  unstable  mineral  salts.  The  fixed  residue  is  an  index 
of  the  mineral  content  of  the  water.  With  waters  low  in  organic  mat- 
ter, but  relatively  high  in  iron,  the  fixed  residue  is  frequently  used  as 
a  matter  of  convenieiice  for  the  determination  of  iron.  In  water  analysis 
it  is  usual  to  note  the  character  of  the  odor  upon  ignition  of  the  residue. 
This  may  be  earthy,  or  may  suggest  organic  matter  of  vegetable  origin  or 
animal  origin. 

The  amount  of  total  solids  in  a  water  depends  upon  the  character 
of  the  soil  with  which  the  water  has  been  in  contact,  the  length  of  expos- 
ure, and  the  amount  of  carbon  dioxid  in  the  water  to  favor  the  solution 
of  inorganic  salts.  Some  mineral  springs  contain  very  large  amounts  of 
28 


834  SANITAEY  ANALYSTS  OF  WATER 

total  solids,  derived  from  deeply  situated  natural  deposits,  as,  for  ex- 
ample, the  springs  at  Saratoga,  Carlsbad,  Kissiiigen,  etc. 

The  permissible  amount  of  solids  as  represented  by  the  residue  on 
evaporation,  which  consists  of  the  dissolved  mineral  constituents,  can- 
not be  arbitrarily  stated,  but  500  parts  per  million  are  generally  held 
as  excessive. 

HARDNESS 

The  quality  of  hardness  in  water  is  more  of  an  economic  question 
than  one  of  sanitary  interest,  except,  perhaps,  as  the  encouragement  of 
the  use  of  soap  and  cleanliness  is  of  fundamental  importance  in  hygiene 
and  sanitation.  Hardness  in  water  is  due  to  the  presence  of  the  soluble 
salts  of  the  alkaline  earths — especially  calcium  and  magnesium.  These 
salts  form  a  curd  with  soap  instead  of  a  lather,  hence  more  or  less  soap 
must  be  wasted  in  decomposing  the  lime  and  magnesia  compounds 
before  a  lather  will  form.  Thus,  one  grain  of  calcium  carbonate,  for 
example,  will  use  up  8  grains  of  soap  before  a  lather  can  be  produced; 
in  this  way  hard  water  causes  an  enormous  waste  of  soap.  In  Europe, 
hardness  is  usually  expressed  in  degrees.  Each  degree  corresponds  to 
one  grain  of  carbonate  of  lime  or  its  equivalent  of  other  lime  or  mag- 
nesium salts  in  a  gallon  of  water. 

The  hardness  of  water  is  called  "temporary"  or  "permanent,"  de- 
pending upon  the  solubility  of  the  salts  it  contains.  Temporary  hardness 
is  due  to  calcium  or  magnesium  carbonate  held  in  solution  as  a  bicar- 
bonate by  the  dissolved  COg.  The  hardness  is  "temporary"  because  the 
CO2  is  driven  off  by  boiling,  and  the  soluble  bicarbonates  are  precipi- 
tated as  insoluble  carbonates.^     The  reaction  is  as  follows : 

CaH2(C03)2  +  heat    =CaC03_+  CO2  +  H2O 

Calcium  bicarbonate  =      Calcium  carbonate 

(Soluble)  (Insoluble) 

Permanent  hardness,  on  the  other  hand,  is  due  mainly  to  sulphates 
and  chlorids  of  calcium  or  magnesium.  These  salts  are  stable  and,  there- 
fore, are  not  precipitated  by  boiling. 

Waters  under  4  degrees  of  hardness  may  be  considered  soft,  those 
exceeding  12  degrees  hard.  Fifty  parts  per  million  of  calcium  sulphate 
and  chlorid  of  magnesium  is  usually  regarded  as  excessive.  Boiler  scale 
is  usually  due  to  deposits  of  sulphates  and  carbonates  of  calcium  and 
magnesium. 

Eain  water  is  always  soft;  surface  waters  vary,  but  are  usually  not 
very  hard ;  ground  waters  are  apt  to  be  hard. 

*  Calcium  carbonate  is  very  slightly  soluble  in  cold  water — 0.0013  parts 
per  100  parts;  magnesium  carbonate  0.088  parts  per  100. 


HAEDNESS  835 

Two  conditions  must  be  present  to  make  a  ground  water  hard :  first, 
the  material  through  which  the  water  passes  must  contain  lime  or  mag- 
nesia, and,  second,  the  conditions  must  be  favorable  for  dissolving  it. 
The  latter  practically  means  that  CO2  must  be  present. 

Waters  drawn  from  limestone  regions  vary  greatly  in  hardness.  Eain 
water  contains  but  little  carbonic  acid  and,  therefore,  has  little  power 
of  dissolving  lime.  The  principal  source  of  the  carbonic  acid  in  ground 
water  is  from  the  soil,  resulting  from  the  decomposition  of  organic  mat- 
ter. The  hardness  of  water,  therefore,  depends  more  upon  the  nature 
of  the  catchment  area  than  upon  the  amount  of  lime  in  the  various 
materials  over  which  the  water  flows.  Thus,  the  water  supply  of  Vienna 
is  comparatively  soft,  notwithstanding  that  it  comes  entirely  from  lime- 
stone rocks.  The  mountainous  region  which  forms  the  catchment  area 
is  barren  and  sterile,  and  the  water  does  not  get  the  carbonic  acid  needed 
to  dissolve  the  lime.  The  Winnipeg  water  drawn  from  limestone  under- 
lying the  rich  prairies  is  excessively  hard.  It  is  interesting  to  note  that 
many  deep  well  waters  of  eastern  Massachusetts  are  comparatively  soft, 
although  they  contain  large  amounts  of  carbonic  acid. 

Very  hard  water  may  be  softened  upon  a  large  scale  with  iron  and 
lime.  As  a  rule,  methods  of  eoftening  are  required  with  ground  waters 
rather  than  with  surface  waters. 

The  common  method  in  use  is  the  Clark  process,  in  which  lime  is 
added  to  the  water  either  in  the  form  of  freshly  slaked  lime  or  milk 
of  lime.  The  calcium  hydroxid  unites  with  the  carbon  dioxid  in  the 
water,  forming  calcium  carbonate,  which  is  insoluble,  and  at  the  same 
time  precipitates  the  calcium  carbonate  held  in  solution  in  the  water  by 
the  CO2.  Sodium  carbonate  is  used  to  reduce  the  permanent  hardness 
of  water  due  to  sulphates. 

When  bicarbonate  of  lime  or  magnesia  are  precipitated  with  lime 
water  the  following  reaction  takes  place : 


Ca(HC03)2           -\-           Ca(0H)2 

2CaC03          +    2H2O 

Calcium  bicarbonate    +    Calcium  hydroxid    = 

=    Calcium  carbonate  -|-  Water 

CaCOs  =  100                     CaO  =  56 

2  X  100                2  X  18 

(Note:  The  hardness  of  water  is  always  expressed  in  terms  of  CaCOs, 
therefore,  all  calcium  and  magnesium,  salts  which  cause  hardness  are  re- 
duced to  terms  of  CaCOa. 

The  amount  of  lime  added  is  weighed  as  unslaked  lime  (CaO),  therefore, 
the  molecular  weight  of  slaked  lime  (CaOH2)  is  expressed  in  terms  of  CaO.) 

One  grain  of  CaO  per  gallon  =  17.1  parts  per  million. 
17.1  X  ^y-    =  31  parts  per  million  as  CaCOa- 
Or,  100  parts  per  million  CaCOg  will  require  3.3  grains  per  gallon. 
CaO  =  455  pounds  per  million  gallons. 

When  sulphates  and  chlorids  of  lime  and  magnesia  are  precipitated 
with  soda  ash,  the  reactions  are: 


836 


SANITAEY  AliALYSIS  OF  WATER 


CaS04  +  NaaCOs      .    =  CaCOa  +         Na2S04 

Calcium  sulphate  +  Sodium  carbonate  =  Calcium  carbonate  +  Sodium  sulphate 
CaCOs  =  100  106  100  142 

1  grain  of  NagCOg  per  gallon  ^  17.1  parts  per  million. 

17.1  X  tH    ^^  16  parts  per  million  as  CaCOg,  but  present  as  CaS04. 

Or,  100  parts  per  million  will  require  6.4  grains  of  IsTagCOg  per  gal- 
lon =  900  pounds  per  million  gallons. 

Methods. — The  hardness  of  water,  both  temporary  and  permanent,  is 
determined  by  the  soap  method.  By  far  the  most  accurate  method  of 
determining  the  true  temporary  hardness  due  to  the  bicarbonate  alkalin- 
ity is  to  titrate  the  original  sample  of  water,  and  also  some  of  the  water 
after  boiling,  with  f-jy  sulphuric  acid,  using  lacmoid  or  erythrosin  as  an 
indicator,  as  already  described  under  Eeaction,  page  832. 

The  soap  method  is  carried  out  as  follows :  Measure  50  c.  c.  of  the 
water  into  a  250-c.  c.  bottle  and  add  the  standard  soap  solution  in  small 
quantities  at  a  time  (from  0.2  to  0.3  c.  c),  shaking  the  bottle  vigor- 
ously after  each  addition  until  a  lather  forms  over  the  entire  surface  of 
the  water,  and  remains  continuous  for  5  minutes  after  the  bottle  is  laid 
upon  its  side.  From  the  amount  of  soap  solution  added,  the  quantity 
of  calcium  carbonate  equivalent  to  each  cubic  centimeter  of  the  soap 
solution  is  indicated  in  the  following  table : 

Table  of  hardness,  showing  the  parts  'per  million  of  calcium  carbonate  (CaCOs)  for  each 
tenth  of  a  cubic  centim,eter  of  soap  solution  when  50  c.c.  of  the  sample  are  used 


c.c.  of  Soap 

0.0 

0.1 

0,2 

0.3 

0.4 

0.5 

0,6 

0.7 

0.8 

0.9 

Solution 

c.c. 

CO. 

c.c. 

c.c. 

c.c. 

c.c. 

CO. 

c.c. 

c.c. 

CO. 

0.0 

0.0 

1.6 

3.2 

1.0 

4.8 

6.3 

7.9 

9.5 

ii.i 

i2.7 

i4.3 

15.6 

16.9 

18.2 

2.0 

19.5 

20.8 

22.1 

23.4 

24.7 

26.0 

27.3 

28.6 

29.9 

31.2 

3.0 

32.5 

33.8 

35.1 

36.4 

37.7 

38.0 

40.3 

41.6 

42.9 

44.3 

4.0 

45.7 

47.1 

48.6 

50.0 

51.4 

52.9 

54.3 

55.7 

57.1 

58.6 

5.0 

60.0 

61.4 

62.9 

64.3 

65.7 

67.1 

68.6 

70.0 

71.4 

72.9 

6.0 

74.3 

75.7 

77.1 

78.6 

80.0 

81.4 

82.9 

84.3 

85.7 

87.1 

7.0 

88.6 

90.0 

91.4 

92.9 

94.3 

95.7 

97.1 

98.6 

100.0 

101.5 

To  translate  parts  per  million  to  degrees  of  hardness,  use  the  follow- 
ing table: 

Conversion  table  of  hardness 


Parts 


Parts  per  miUion 
Clark  degrees .  .  . 
French  degrees. . 
German  degrees. 


Parts  per 
Million 


1.00 
14.3 
10.0 
17.8 


Clark 
Degrees 


0.07 
1.00 
0.70 
1.24 


French 
Degrees 


0.10 
1.43 
1.00 

1.78 


German 
Degrees 


0.56 
0.80 
0.56 
1.00 


English  degrees  of  hardness    (Clark's  scale)  represent  grains  of  calcium 
carbonate  per  imperial  gallon. 


OEGANIC  MATTEE  837 

French  degrees  of  hardness  represent  parts  per  100,000  of  calcium  car- 
bonate, r      1    ■ 

German  degrees  of  hardness  represent  parts  per  100,000  ol  calcium  oxide. 

To  convert  hardness  from  one  scale  to  another,  multiply  by  the  factor 
opposite  the  scale  in  which  it  is  expressed  and  under  the  scale  to  which  it 
is  to  be  converted.  Thus  to  convert  parts  per  million  to  Clark  degrees, 
multiply  by  0.07. 

In  adding  the  soap  solution  to  waters  containing  magnesium  salts 
it  is  necessary  to  avoid  mistaking  the  false  or  magnesium  end-point  for 
the  true  one.  If  the  end-point  was  due  to  magnesium  the  lather  now  dis- 
appears. Soap  solution  must  then  be  added  until  the  true  end-point 
is  reached.  Usually  the  false  lather  persists  for  less  than  5  minutes. 
Consequently,  after  the  titration  is  apparently  finished,  read  the  burette 
and  add  about  0.5  c.  c.  of  soap  solution. 

At  best  the  soap  method  is  not  a  precise  test  on  account  of  the  vary- 
ing proportions  of  calcium  and  magnesium  present  in  diiferent  waters. 
For  the  determination  of  hardness,  especially  in  connection  with  proc- 
esses for  purification  and  softening,  it  is  advisable  to  use  volumetric 
or  gravimetric  methods. 

ORGANIC  MATTER 

It  is  not  possible  to  determine  the  amount  of  organic  matter  pres- 
ent in  a  sample  of  water  by  any  direct  method.  As  all  protein  matter 
contains  nitrogen,  methods  have  been  devised  to  determine  the  total 
amount  of  nitrogen  and  also  the  amount  of  nitrogen  in  various  com- 
binations. From  such  data  valuable  information  concerning  the  sani- 
tary history  and  sanitary  quality  of  the  water  may  be  inferred.  The 
nitrogen  is  determined  as  (1)  total  nitrogen;  (2)  nitrogen  as  free  am- 
monia; (3)  nitrogen  as  albuminoid  ammonia;  (4)  nitrogen  as  nitrites; 
(5)  nitrogen  as  nitrates. 

The  organic  matter  in  water  is  of  animal  and  vegetable  origin  and 
exists  both  in  solution  and  in  suspension.  Some  of  it  is  in  the  body 
of  living  beings;  some  of  it  is  in  their  dead  bodies;  and  some  of  it 
is  in  various  stages  of  decomposition  until  the  final  stable  compounds, 
such  as  ammonia  and  nitrates,  are  reached.  The  total  amount  of  or- 
ganic matter  present  in  a  sample  of  water  is  represented  by  the  amount 
of  nitrogen  as  free  ammonia  and  albuminoid  ammonia.  The  presence 
of  nitrogen  as  nitrites  and  nitrates  indicates  the  amoimt  of  self -purifica- 
tion which  the  water  has  undergone.  Their  significance  will  be  dis- 
cussed separately. 

Free  Ammonia. — If  there  is  much  free  ammonia  in  the  water  the 
sample  may  be  nesslerized  directly.  If  the  water  contains  comparatively 
little,  as  is  usually  the  case,  the  ammonia  must  first  be  concentrated 
by  distillation  and  condensation. 


838  SANITARY  ANALYSIS  OF  WATER 

Place  500  c.  c,  of  the  sample  of  water  in  a  metal  or  glass  still  con- 
nected to  a  tin  or  aluminium  condenser  in  such  a  way  that  the  dis- 
tillate may  be  conveniently  delivered  directly  into  Nessler  tubes.  The 
entire  apparatus  must  first  be  freed  from  ammonia  by  Idowiiig  steam 
through  it  until  the  distillate  shows  no  trace  of  free  ammf)riia.  Wheii 
this  has  been  done  the  distilling  flask  is  emptied  and  500  c.  c.  of  the 
sample  of  water  measured  into  it.  The  distillation  should  be  carried 
on  at  a  rate  so  that  not  more  than  10  c.  c.  nor  less  than  6  c.  c.  condense 
per  minute;  that  is,  it  should  take  from  5  to  10  minutes  to  distill  50 
c.  c,  which  is  the  quantity  Nessler  tubes  are  ordinarily  graduated  to 
contain.  Three  Nessler  tubes  of  the  distillate  containing  50  c.  c.  each 
are  collected  from  the  first  portion  that  comes  over;  these  contain  the 
free  ammonia. 

If  the  sample  is  acid,  or  if  the  presence  of  urea  is  suspected,  about 
one-hal|  gram  of  sodium  carbonate  should  be  added  previous  to  dis- 
tillation, otherwise  the  ammonia  will  not  come  off.  Sodium  carbonate 
is  omitted,  when  possible,  as  it  tends  to  increase  "bumping." 

The  amount  of  ammonia  is  determined  by  adding  2  c.  c.  of  Nessler 
reagent  to  each  tube  and  comparing  the  depth  of  color  with  a  set  of 
standard  tubes  prepared  with  a  known  quantity  of  ammonium  chlorid 
solution,  plus  an  equal  quantity  of  Nessler  reagent. 

Nessler' s  reagent  is  prepared  by  dissolving  50  grams  of  potassium 
iodid  in  a  minimum  quantity  of  cold  water.  To  this  add  a  saturated 
solution  of  mercuric  chlorid  until  a  slight  permanent  precipitate  per- 
sists. Then  add  125  grams  of  potassium  hydroxid  dissolved  in  250  c.  c. 
of  water,  allowing  it  to  clarify  by  sedimentation  before  using;  dilute 
to  one  liter,  allow  to  stand,  and  decant.'^  The  solution  should  give 
the  required  color  with  ammonia  within  5  minutes  after  addition, 
and  should  not  precipitate  with  small  amounts  of  ammonia  within 
2  hours.  The  reaction  between  Nessler's  reagent  and  ammonia  is  an 
empiric  one.  The  Hgl22KIKOII,  which  constitutes  the  Nessler's 
reagent  in  the  presence  of  ammonia,  forms  a  brownish  compound 
which  is  known  as  mercurammonium  iodid,  and  has  the  formula 
NHg,IH,0. 

Standaed  NH^Cl  Solution. — The  standards  for  comparison  con- 
sist of  ammonium  chlorid  dissolved  in  ammonia-free  water.  Dissolve 
3.82  grams  of  ammonium  chlorid  in  1  liter  of  water;  dilute  10  c.  c. 
of  this  to  1  liter  with  the  ammonia-free  water.  One  c.  c.  will  then 
equal  0.00001  gram  of  nitrogen. 

A  gram  molecule  of  NH^Cl  weighs  53.5  grams — that  is: 

N  14  4-  H  4  -h  CI  35.5  =  53.5 

*  Another  method  of  making  Nessler's  reagent  will  be  found  in  Suttcn's 
"Volumetric  Analysis." 


OEGANIC  MATTER  839 

The  equation  would  then  he: 

14  :  53.5  ::  1  :x 
X  =  3.83 

That  is,  if  there  are  14  grams  of  nitrogen  in  53.5  grams  of  am- 
monium chlorid,  then  1  gram  of  nitrogen  is  contained  in  3.83  grams 
of  ammonium  chlorid.  It  is  to  be  noted  that,  while  the  method  deter- 
mines the  amount  of  ammonia,  the  results  are  expressed  in  terms  of 
nitrogen.  In  the  same  way  the  nitrites  and  nitrates  are  also  expressed 
in  terms  of  nitrogen. 

Prepare  a  series  of  16  Nessler  tubes,  which  contain  the  following 
number  of  cubic  centimeters  of  the  standard  ammonium  chlorid  solu- 
tion, namely :  0.0,  0.3,  0.5,  0.7,  1.0,  1.5,  3.0,  3.5,  3.0,  3.5,  4.0,  4.5,  5.0, 
6.0 ;  dilute  each  one  to  the  50  c.  c.  mark  with  ammonia-free  water.  These 
will  contain  0.00001  gram  of  nitrogen  for  each  cubic  centimeter  of  the 
standard  solution  used.  Add  3  c.  c.  of  the  ISTessler  reagent  to  each 
tube ;  do  not  stir  the  contents  of  the  tubes. 

The  color  produced  in  the  distillate  from  the  sample  under  exam- 
ination is  now  compared  with  standards  by  looking  vertically  down- 
ward through  them  at  a  white  surface  placed  at  an  angle  in  front  of 
a  window  so  as  to  reflect  the  light  upward.  The  tubes  should  be  allowed 
to  stand  at  least  10  minutes  after  nesslerizing  before  making  the  com- 
parison. 

The  last  50  cubic  centimeters  of  the  distillate  examined  should  con- 
tain no  ammonia,  or  at  most  a  trace,  otherwise  it  may  be  inferred  that 
all  has  not  been  collected,  or  some  error  has  crept  into  the  work.  It  is 
not  uncommon  for  the  last  tube  to  contain  a  little  ammonia  when  the 
organic  matter  is  of  plant  origin.  Ammonia  determinations  should 
be  carried  out  in  a  special  room,  where  at  least  volatile  ammonia  re- 
agents are  not  exposed.  Special  care  must  be  exercised  not  to  contam- 
inate the  Nessler  tubes  with  soiled  fingers,  rags,  etc.  Care  must  be  exer- 
cised to  thoroughly  wash  the  tubes  free  from  alkaline  soaps,  and  to  rinse 
with  ammonia-free  water.  The  Nessler  tubes  containing  the  standard 
solution  and  the  samples  for  comparison  should  be  at  the  same  tem- 
perature, and  other  conditions  should  be  as  alike  as  possible. 

Example. — 

The  first  ISTessler  tube=:3.5  c.  c.  standard  NH^Cl  solution,  or 
0.000,035  gram  N  as  NH3. 

The  second  Nessler  tube=0.7  c.  c.  standard  ]SrH4Cl  solution,  or 
0.000,007  gram  N  as  NH3. 

The  third  Nessler  tube=0.0  c.  c.  standard  NH4CI  solution,  or 
0.000,000  gram  N  as  Nil,,. 

Total,  0.000,033  gram  N  as  NH3. 


840  SANTTAEY  ANALYSTS  OF  WATER 

(Note:  1  c.  c.  of  the  standard  solution  contains  0.00001  gram  of 
N  as  NH3.) 

Only  500  c.  c.  of  the  sample  of  water  was  distilled.  We  must,  there- 
fore, multiply  by  2  in  order  to  obtain  the  amount  of  N  in  one  liter: 

0.000,032X2=0.000,064  gram  of  N  as  NH,  per  1,000  c.  c. 

If  1,000  c.  c.  contains  0.000,064  gram  of  N  as  NH3,  1,000,000  parts 
will  contain  0.064  part  of  N  as  NH3 — usually  expressed  as  0.064  part 
per  million. 

A  simpler  method  of  making  the  calculation  is  as  follows: 

First  Nessler  tube 2.5 

Second   Nessler   tube 0.7 

Third  Nessler  tube 0.0 

3.2X0.02=0.064  part  per  million. 

Significance  of  Feee  Ammonia. — The  free  ammonia  which  comes 
off  with  the  first  part  of  the  distillate  usually  exists  in  the  water  as 
chlorids  or  carbonates.  Jt  is  called  "free  ammonia"  because  these  salts 
are  readily  decomposed  and  the  ammonia  is  expelled  by  boiling. 

Eain  water  washes  down  some  free  ammonia  which  is  found  in  the 
atmosphere.  Angus  Smith  and  Boussingault  place  the  average  amount 
of  ammonia  in  the  rain  of  temperate  climates  as  0.5  part  per  million. 

The  amount  of  ammonia  in  rain  water  was  studied  by  Filhol.  He 
found  that  in  the  city  of  Toulouse  the  rain  water  contained  6.60  parts 
per  million,  while  the  rain  water  collected  near  the  city  contained  only 
from  0.44  to  0.77  part  per  million.  These  figures  show  the  marked  dif- 
ference between  city  and  country  rain. 

In  a  surface  or  ground  water  free  ammonia  represents  one  of  the 
latter  stages  of  putrefaction  of  organic  matter;  thus,  the  bacterial  de- 
composition of  sewage  yields  ammonia  in  abundance. 

The  ammonia  itself  ordinarily  found  in  drinking  water  is  harmless; 
its  significance  lies  in  the  fact  that  it  indicates  the  presence  of  putre- 
fying organic  matter. 

The  presence  of  free  ammonia  in  clean  and  properly  stored  rain 
water  has  much  less  significance  than  in  a  surface  or  ground  water. 

Free  ammonia  in  water  results  not  only  from  the  decomposition  of 
nitrogenous  organic  matter,  but  is  also  formed  during  the  process  of 
denitrification,  by  which  nitrates  are  again  reduced  to  nitrites  and 
nitrites  to  ammonia.  This  action  only  takes  place  near  the  surface 
of  the  soil,  and  to  a  limited  extent.  Deep  well  waters  of  exceptional 
purity  upon  chemical  analysis,  and  practically  sterile  upon  bacteriologi- 
cal examination,  may  contain  a  relatively  high  percentage  of  free  am- 
monia.    This  is  supposed  to  come  from  a  chemical  reduction  under 


OEGANIC  MATTER  841 

high  pressure  and  perhaps  temperature  of  the  geological  nitrogenous 
matter  in  coal  and  alluvial  deposits. 

A  definite  permissible  limit  for  the  amount  of  free  ammonia  which 
good  water  should  contain  cannot  be  fixed.  Its  significance  must  be 
judged  from  the  other  constituents  of  the  water  and  a  sanitary  survey 
of  its  source.  As  a  rule,  safe  water  may  contain  from  0.015  to  0.03 
or  even  0.055  part  per  million.  In  general,  free  ammonia  is  less  of 
a  danger  signal  than  the  fixed  or  albuminoid  ammonia. 

Albuminoid  Ammonia. — Nitrogen  as  albuminoid  ammonia  is  always 
determined  in  conjunction  with  and  as  a  continuation  of  the  method 
for  determining  nitrogen  as  free  ammonia.  After  obtaining  150  c.  c. 
(that  is,  3  Nessler  tubes  of  50  c.  c.  each)  from  the  first  portion  of  the 
distillate,  for  the  purpose  of  determining  nitrogen  as  free  ammonia, 
withdraw  the  flame,  disconnect  the  flask  and  add  40  c.  c.  or  more  of  hot 
alkaline  potassium  permanganate,  and  continue  the  distillation  until 
at  least  4  portions  of  50  c.  c.  each,  or,  preferably,  5  portions,  of  the 
distillate  have  been  collected  in  separate  Nessler  tubes. 

The  calculation  is  as  follows: 

First  ISTessler  tube 1.7 

Second  ISTessler  tube 0.8 

Third  ISTessler  tube 0.5 

Fourth  Nessler  tube 0.3 

Fifth  Nessler  tube 0.3 


3.6X0.03=0.073  parts  per  million. 

The  alkaline  potassium  permanganate  solution  is  made  by  pouring 
1,300  c.  c.  of  distilled  water  into  a  porcelain  dish  holding  3,500  c.  c. ; 
boil  10  minutes  and  turn  off  the  gas.  Add  16  grams  of  C.  P.  potas- 
sium permanganate  and  stir  until  dissolved.  Then  add  800  c.  c.  of  50 
per  cent,  clarified  solution  of  potassium  or  sodium  hydrate  and  enough 
distilled  water  to  fill  the  dish.  Boil  down  to  3,000  c.  c.  Test  each  batch 
of  this  solution  for  albuminoid  ammonia  by  making  a  blank  determi- 
nation.    Correction  should  be  made  accordingly. 

After  the  readily  decomposed  ammonia  salts  have  been  broken 
up  and  the  ammonia  driven  off  in  the  steam  which  condenses  to  form 
the  first  150  c.  c,  the  remainder  of  the  sample  of  water  in  the  still  con- 
tains nitrogenous  organic  matter  that  requires  a  strong  oxidizing  agent 
to  disintegrate  it.  This  is  accomplished  by  the  alkaline  potassium  per- 
manganate. The  nitrogen  in  the  complex  protein  molecule  finally  forms 
ammonia,  and  hence  this  is  called  albuminoid  ammonia;  the  amount 
of  it  is  determined  by  nesslerization,  precisely  as  for  free  ammonia. 
In  ground  waters  and  surface  waters  containing  but  little  pollution  the 
nitrogen  as  albuminoid  ammonia  usually  approximates  about  one-half 


842  SANITARY  ANALYSIS  OF  WATER 

of  the  total  organic  nitrogen.  In  sewage  and  other  liquids  containing 
considerable  nitrogenous  organic  matter  the  percentage  of  ammonia 
forming  organic  matter  is  variable.  For  this  reason  the  amount  of 
albuminoid  ammonia  obtained  by  the  alkaline  permanganate  method 
is  less  valuable  than  the  total  organic  nitrogen  determined  by  the  KJel- 
dahl  method. 

If  it  is  desired  to  determine  how  much  of  the  organic  matter  is  in 
isolution  and  how  much  in  suspension,  the  sample  of  water  should  be 
passed  through  a  Berkefeld  filter.  The  albuminoid  ammonia  in  the 
filtrate  represents  the  dissolved  organic  matter,  and  the  difference  be- 
tween the  albuminoid  ammonia  in  the  total  sample  and  the  filtered 
sample  gives  the  suspended  nitrogen  as  albuminoid  ammonia. 

The  albuminoid  ammonia  is  a  fairly  correct  index  of  the  amount 
of  organic  pollution  in  the  water.  It  comes  from  minute  organisms, 
both  living  and  dead,  that  are  in  the  sample,  also  from  particles  of 
animal  and  vegetable  matter  in  suspension,  and  finally  from  the  nitrog- 
enous substances  in  solution  and  in  various  stages  of  decomposition. 
The  organic  matter  in  itself  is  not  dangerous  to  health,  but  is  unde- 
sirable because  it  putrefies  and  thus  gives  a  water  disagreeable  tastes 
and  odors;  further,  it  offers  food  for  bacterial  growth.  The  amount 
of  albuminoid  ammonia  is  therefore  an  index  of  pollution,  but  if  of 
vegetable  origin  it  has  much  less  sanitary  significance  than  if  of  animal 
origin.  Organic  matter  of  animal  origin  yields  a  much  larger  amount 
of  albuminoid  ammonia  than  a  similar  amount  of  vegetable  matter. 
Whether  the  organic  matter  comes  from  sewage,  from  a  dead  carcass, 
or  from  the  swamps,  cannot  be  stated  with  certainty  from  this  test,  but 
if  the  albuminoid  ammonia  comes  over  quickly,  that  is,  if  most  of  it 
appears  in  the  first  Nessler  tube,  it  is  presvimably  of  animal  origin; 
whereas,  if  the  ammonia  conies  over  more  slowly  and  the  second  and 
third  Nessler  tubes  contain  appreciable  amounts,  the  organic  matter  is 
presumably  of  vegetable  origin. 

No  arbitrary  standard  can  be  set  as  to  the  maximum  amount  of 
albuminoid  ammonia  a  good  water  may  contain.  Waters  considered 
"pure"  often  contain  as  much  as  0.079  to  0.34  part  of  nitrogen  as  al- 
.buminoid  ammonia  per  million. 

Nitrites. — Nitrites  in  water  are  regarded  as  a  special  danger  signal. 
'The  reason  for  this  is  that  nitrites  indicate  that  active  putrefaction  of 
initrogenous  organic  matter  is  going  on  as  the  result  of  bacterial  activ- 
iity.  The  presence  of  nitrites,  therefore,  at  once  suggests  organic  pollu- 
tion. The  presence  of  nitrites  in  water  represents  the  transitional  stage 
;in  the  oxidation  of  organic  matter  between  ammonia  and  nitrates,  and 
therefore  indicates  incomplete  oxidation  of  the  protein  and  the  active 
growth  of  bacteria. 

Nitrites  are  never  present  except  in  small  amounts,  for  they  are  soon 


OEGANIC  MATTER  843 

oxidized  to  the  higher  and  more  stable  nitrates,  but  the  minutest  trace, 
according  to  some  authorities,  is  sufficient  to  condemn  a  water.  As  a 
rule,  pure  water  contains  no  nitrites,  or  traces  only ;  on  the  other  hand, 
nitrites  may  be  absent  from  an  impure  water,  owing  to  the  fact  that 
the  oxidation  has  not  reached  this  stage,  or  perhaps  has  entirely  passed 
it.  The  absence  of  nitrites,  therefore,  does  not  mean  that  the  water  is 
necessarily  safe,  while  their  presence  in  any  but  the  smallest  measurable 
amounts  shows  pollution.  We  must  not  give  to  the  nitrites  an  exag- 
gerated importance:  they  are  a  danger  signal  in  the  same  sense  that 
the  colon  bacillus  is  a  danger  signal,  indicating  pollution  but  not  neces- 
sarily infection,  for  they  do  not  tell  the  source  or  nature  of  the  organic 
matter.  The  presence  of  nitrites  in  spring  and  deep  well  water  may 
be  without  sanitary  significance,  for  in  these  cases  they  may  be  gen- 
erated by  the  deoxidation  of  the  nitrates  which  is  brought  about  either 
by  the  action  of  reducing  substances,  such  as  ferrous  oxid,  or  by  organic 
matter.  It  should  be  remembered  that  the  colorimetric  test  for  nitrites 
with  sulphanilic  acid  and  a-amidonaphthylamin  is  one  of  the  most  deli- 
cate tests  in  chemistry.  With  this  method  we  are  able  to  detect  quan- 
tities as  small  as  one  part  in  a  hundred  million.  When,  therefore,  a 
water  analyst  reports  a  trace  of  nitrites  it  means  an  exceedingly  minute 
quantity. 

Nitrites  are  not  only  formed  by  the  nitrifying  bacteria  in  the  soil 
from  ammonia,  but  are  also  formed  from  the  denitrification  of  nitrates 
by  a  variety  of  microorganisms.  The  typhoid  bacillus,  the  colon  bacillus, 
and  many  other  bacteria  have  the  power  of  producing  nitrites  in  culture 
media, 

Nitrites  are  poisonous,  but  the  minute  amounts  found  in  water  can 
scarcely  have  a  pharmacological  effect. 

Method  foe  Estimating  Nitrogen  as  '^Hitrites.— Reagents :  (!)• 
Sulphanilic  acid  solution.  Dissolve  eight  grams  of  the  purest  sulphanilic 
acid  in  1,000  c.  c.  of  5  K.  acetic  acid  (sp.  gr.  1.041).  This  is  prac- 
tically a  saturated  solution. 

(2)  a-amidonaphthalene  acetate  solution.  Dissolve  5.0  grams  solid 
a-naphthylamin  in  1,000  c.  c.  of  5  N.  acetic  acid;  filter  the  solution 
through  washed  absorbent  cotton. 

(3)  Sodium  nitrite,  stock  solution.  Dissolve.  1.1  grams  silver  ni- 
trite in  nitrite-free  water;  precipitate  the  silver  with  sodium  chlorid 
solution  and  dilute  the  whole  to  one  liter. 

(4)  Standard  sodium  nitrite  solution.  Dilute  100  c.  c.  of  solution 
(3)  to  one  liter;  then  dilute  10  c.  c.  of  this  solution  to  one  liter  with 
sterilized  nitrite-free  water;  add  one  c.  c.  of  chloroform  and  preserve 
in  a  sterilized  bottle.     One  c.  c.  =  0.000,000,1  gram  nitrogen. 

Procedure. — Measure  out  100  c.  c.  of  the  decolorized  sample  (de- 
colorized   by    adding    aluminium    hydrate   free    of    nitrite — see    under 


844  SANITAEY  ANALYSIS  OF  WATER 

Chlorin),  or  a  smaller  portion  diluted  to  100  c.  c,  into  a  Xessler  tube. 
At  the  same  time  make  a  set  of  standards  by  diluting  various  volumes 
of  the  standard  nitrite  solution  in  Nessler  tubes  to  100  c.  c.  with  nitrite- 
free  water,  for  example,  0,  1,  3,  5,  7,  10,  14,  17,  20,  and  25  c.  c.  Add 
2  c.  c.  each  of  reagents  Nos.  1  and  2  (above)  to  each  100  c.  c.  of  the  sam- 
ple and  to  each  standard.  Mix;  allow  to  stand  10  minutes.  Compare 
the  samples  with  the  standards.  Do  not  allow  the  samples  to  stand  over 
one-half  hour  before  being  compared,  on  account  of  absorption  of  nitrites 
from  the  air.  Make  a  blank  determination  in  all  cases  to  correct  for 
the  presence  of  nitrites  in  the  air,  the  water  and  other  reagents.  Dilute 
all  samples  which  develop  more  color  than  the  25  c.  c.  standard  before 
comparing.     Mixing  is  important. 

When  100  c.  c.  of  the  sample  are  used,  then  0.001  times  the  number 
of  c.  c.  of  the  standard  gives  the  parts  per  million  of  nitrogen  as  nitrite. 

Calculation. — One  c.  c.  of  the  standard  equals  .0001  mgs,  N.  as 
nitrites.  100  c.  c.  of  the  sample  is  used  and  is  found  to  equal  5  c.  c.  of 
the  standard. 

Then  100  c.  c.  sample  contains  .0005  mgs.  N.  as  nitrites  and  one 
liter  will  contain  10  X  0.0005  or  .005  mgs.  of  N.  or  .005  parts  per  mil- 
lion. 

When  100  c.  c.  of  the  sample  is  used  10  X  .0001  X  the  number 
c.  c.  of  the  standard  will  give  the  number  mgs.  IST.  per  liter  or  parts 
per  million.  This  can  be  shortened  to  .001  X  the  number  c.  c.  standard 
used  equals  parts  per  million  of  N.  as  nitrites. 

Nitrates. — Nitrates  are  the  end  products  of  the  mineralization  of 
organic  matter.  Their  presence,  therefore,  signifies  past  or  distant 
pollution.  While  the  absence  of  nitrates  does  not  necessarily  mean 
purity,  their  presence,  on  the  other  hand,  does  not  necessarily  indicate 
immediate  danger.  If  a  water  contains  an  appreciable  quantity  of  ni- 
trates and  no  nitrites,  it  shows  that  the  source  of  pollution  has  been 
distant  and  that  the  organic  matter  has  been  completely  oxidized.  In 
waters  considered  pure  the  nitrates  are  rarely  less  than  0.3  part,  or 
they  may  run  as  high  as  1.6  parts,  per  million.  Polluted  waters  usually 
contain  very  much  more,  as  17,  20,  or  more  parts  per  million.  Nitrates 
"usually  exist  in  water  as  salts  of  alkaline  bases. 

Young^  has  shown  that  the  ground  waters  of  Kansas  sometimes 
contain  large  amounts  of  nitrates — as  much  as  500  parts  per  million. 
The  medicinal  dose  of  potassium  nitrate  is  0.3  grams.  Less  than  a 
liter  of  water  would  therefore  contain  sufficient  nitrates  to  produce 
therapeutic  effects  such  as  irritation  of  the  mucous  membrane  of  the 
stomach,  resulting  in  gastritis,  and  also  diuresis,  with  irritation  of  the 
mucous  membrane  of  the  bladder. 

The  test  for  nitrates  depends  upon  the  fact  that  they  react  with 

*  Young,  C.  C:  Jour.  A.  M.  A.,  June  24,  1911,  LVI,  p.   1881. 


OEGANIC  MATTER  845 

phenoldisulphonic  acid  to  form  a  compound  resembling  picric  acid, 
which  is  yellow  in  the  presence  of  an  alkali.  The  amount  of  nitrates  is 
determined  colorimetrically  by  comparison  with  standard  solutions. 

Phenolsulphonic  Acid  Method  for  Nitrates. — Reagents:  (1) 
Phenolsulphonic  acid.  Mix  30  grams  of  synthetic  phenol  with  370 
grams  of  C.  P.  concentrated  sulphuric  acid  in  a  round-bottom  flask.  Put 
this  flask  in  a  water  bath  and  support  it  in  such  a  way  that  it  shall 
be  completely  immersed  in  the  water.    Heat  for  six  hours. 

(2)  Ammonium  hydrate  solution  diluted  with  distilled  water,  1  to 
1.  Potassium  hydrate  may  be  used.  The  ammonia  gives  a  better  color 
than  the  potassium,  but  should  not  be  used  if  this  test  is  carried  on  in 
the  same  room  where  free  and  albuminoid  ammonia  are  being  deter- 
mined for  fear  of  false  results  from  contamination. 

(3)  Standard  nitrate  solution.  Dissolve  0.72  gram  of  pure  re- 
crystallized  potassium  nitrate  in  one  liter  of  distilled  water.  Evaporate 
cautiously  10  c.  c.  of  this  strong  solution  on  the  water  bath.  Moisten 
quickly  and  thoroughly  with  2  c.  c.  of  phenolsulphonic  acid  and  dilute  to 
one  liter  for  the  standard  solution;  one  e.  c.  of  which  equals  .000,001 
gram  of  nitrogen. 

Procedure. — Evaporate  20  c.  c.  of  the  sample  of  water  in  a  small 
porcelain  evaporating  dish  on  the  water  bath,  removing  it  from  the 
bath  just  before  it  has  come  to  dryness.  Let  the  last  few  drops  evap- 
orate at  room  temperature  in  a  place  protected  from  the  dust.  When 
the  sample  is  suspected  to  contain  a  large  amount  of  nitrate,  evaporate 
less  than  20  c.  c.    If  it  is  suspected  to  contain  but  little,  evaporate  more. 

If  the  sample  has  a  high  color,  decolorize  before  evaporating  by  the 
use  of  washed  aluminium  hydrate,  as  directed  in  connection  with  the 
chlorin  determination. 

Add  1  c.  c.  of  phenolsulphonic  acid  and  rub  this  quickly  and  thor- 
oughly over  the  residue  with  a  glass  rod.  Add  about  10  c.  c.  of  distilled 
water  and  stir  with  a  glass  rod  until  mixed.  Add  enough  ammonium 
hydrate  solution  (or  potassium  hydrate  if  the  operation  must  of  neces- 
sity be  carried  on  in  a  room  where  ammonia  distillations  are  made)  to 
render  the  liquid  alkaline.  Wash  into  a  100  c.  c.  Nessler  tube  and  fill 
the  tube  to  the  100  c.  c.  mark  with  distilled  water. 

If  nitrates  are  present  there  will  be  formed  a  yellow  color;  this  may 
be  compared  with  permanent  standards  made  for  the  purpose,  which 
keep  satisfactorily  for  several  weeks.  The  series  of  standards  for  com- 
parison shall  be  made  by  putting  varying  quantities  of  the  standard 
solution  into  100  c.  c.  tubes  and  making  up  to  the  100  c.  c.  mark  with 
distilled  water,  adding  5  c.  c.  of  strong  ammonia  to  each  tube.  Each 
c.  c.  of  the  standard  contains  0.001  mg.  of  'N.  as  nitrates.  Nessler  tubes 
containing  1,  3,  5,  7,  10,  15,  20,  25,  30,  35  and  40  c.  c.  of  the  standard 
are  usually  prepared. 


84G  SANITAEY  ANALYSIS  OF  WATER 

Compare  the  sample  treated  as  above  described  with  these  standards 
by  looking  down  vertically  through  the  tubes  at  a  white  surface  so  placed 
in  front  of  a  window  that  it  will  reflect  the  light  npward  through  them. 

If  the  figures  obtained  by  this  comparison,  in  cubic  centimeters  of 
standard  added,  be  divided  by  the  number  of  c.  c.  of  the  sample  which 
were  evaporated,  the  quotient  gives  the  number  of  parts  per  million  of 
nitrogen  in  the  form  of  nitrate. 

Derivation  of  the  Factor. — One  c.  c.  of  the  standard  equals  .001 
mg.  of  nitrogen  as  nitrates.  If  we  find  that  20  c.  c.  of  the  sample 
correspond  to  10  c.  c.  of  the  standard  then  20  c.  c.  of  the  water  contains 
.001  X  10  =  0.01  mg.  of  K  One  liter  (1,000  c.  c.)  will  contain  50 
times  as  much  (.01  X  50)  .5  mg.  of  N. 

Mgs.  per  liter  equals  parts  per  million;  therefore  the  water  con- 
tains .5  parts  of  N.  as  nitrates  per  million. 

Or  to  put  it  differently, 

.001   X   10  c.  c.  standard  used         t^-t   .  r  i       ai. 

=    N   in  mgs.  per  c.  c.  of  sample;    then 

20  c.  c.  of  sample  used 

.001  X  10  X  1000  1.^       . ,.        .001  X  10,000. 

=  mas.  per  liter  of  N  or  

20  ^    ^  20 

This  equals  -1^- :  therefore  the  number  of  c.  c.  of  standard  divided  by 
the  number  of  c.  c.  of  the  sample  used  gives  the  parts  per  million  of 
IST.  as  nitrates. 

CHLORIN 

Chlorin  as  sodium  chlorid  or  common  salt  is  a  normal  constituent 
of  all  waters.  Traces  of  it  are  found  in  rain  water  taken  up  from  the 
air,  especially  near  the  sea-coast.  The  rain  water  collected  at  Troy, 
New  York,  was  found  by  Mason  to  average  1.64  parts  per  million  of 
chlorin.  The  amounts  varied  from  0.75  part  per  million  in  April  to  3 
parts  per  million  in  October.  The  chlorin  in  surface  and  ground  waters, 
generally  speaking,  comes  from  the  mineral  deposits  in  the  earth;  from 
the  ocean  vapors  and  spray  carried  inland  by  the  wind;  also  from  pol- 
luting materials  like  sewage  and  trade  wastes,  both  of  which  are  apt  to 
contain  the  common  salt  used  in  the  household  and  in  manufacturing. 
A  comparison  of  the  chlorin  content  of  a  water  with  that  of  other  waters 
in  the  general  vicinity  known  to  be  unpolluted  frequently  affords  useful 
information  as  to  its  sanitary  quality. 

Before  the  water  analyst  is  able  to  properly  interpret  the  significance 
of  the  chlorin  content  of  a  water  it  is  necessary  to  know  the  normal 
amount  of  chlorin  present  in  the  waters  of  that  locality.  Thus,  surface 
waters  near  Provincetown,  on  Cape  Cod,  contain  from  23  to  24  parts 
of  chlorin  per  million,  while  surface  waters  near  Boston  contain  from 


CHLOEIN  847 

3  to  6  parts  per  million.  Near  the  middle  of  the  state  of  Massachusetts 
(Worcester)  the  surface  waters  contain  only  1.2  to  1.9  parts  per  million, 
while  in  the  western  portion  of  the  state,  farthest  from  the  sea,  the 
surface  waters  contain  but  0.7  to  0.9  parts  per  million.  The  amount 
of  normal  chlorin  in  the  waters  of  Massachusetts  has  been  carefully 
studied  by  the  State  Board  of  Health,  and  a  map  has  been  issued  show- 
ing the  isochlors,  or  normal  chlorin  lines. 

In  Massachusetts  the  whole  of  the  surface  of  the  country,  with  the 
exception  of  a  very  small  portion,  is  non-calcareous,  and  the  surface 
waters  carry  but  little  chlorin  in  composition,  if  unpolluted,  the  amount 
of  chlorin  decreasing  continuously  from  the  coast  inland.  In  a  report 
on  the  State  water  supplies,  1887-1890,  the  Commissioners  state  that 
"in  a  general  way  4  families  or  20  persons  per  square  mile  will  add,  on 
an  average,  .01  of  a  part  per  100,000  of  chlorin  (.1  part  per  million) 
to  the  water  flowing  from  this  area,  and  that  a  muCh  smaller  population 
will  have  the  same  effect  during  seasons  of  low  flow." 

The  amount  of  chlorin  in  a  water  of  a  district  varies  with  several 
factors,  such  as  the  distance  from  the  sea,  the  amount  of  rainfall,  the 
amount  of  evaporation,  and  the  direction  of  the  winds.  An  increase  over, 
the  normal  is  an  indication  of  pollution,  and  comes  mostly  from  urine. 
While  the  ammonia  and  the  nitrites  may  have  disappeared  and  the  ni- 
trates may  have  been  largely  taken  up  by  growing  vegetation,  the  chlorin 
salts,  which  are  exceedingly  stable,  will  be  left  to  indicate  remote  or 
passed  pollution. 

The  mixture  of  even  a  small  proportion  of  sea-water  renders  the 
water  hard  and  salty  and  undesirable  for  domestic  use.  Magnesium 
chlorid  also  renders  a  water  unsuitable  for  use  in  boilers.  Wells  driven 
near  the  sea  frequently  become  mixed  with  sea-water,  particularly  if 
sufiieient  water  is  withdrawn  to  cause  suction.  When  this  happens  the 
sea-water  passes  back  under  the  wells  as  an  undercurrent  and  gradually 
mixes  with  the  fresh  water  above  it  and  sooner  or  later  appears  in  the 
well.  When  this  happens  it  may  be  a  slow  and  hard  process  to  operate 
the  well  so  as  to  avoid  drawing  sea-water.  In  wells  near  the  sea  it  is 
important  to  draw  no  more  fresh  water  than  would  otherwise  flow  to 
the  ocean.  This  is  often  a  difficult  problem  to  arrange  so  as  to  get  the 
maximum  quantity  of  water  obtainable.  This  sea-water  question  has 
been  more  thoroughly  and  scientifically  studied  in  Holland  than  else- 
where. 

Determination  of  Chlorin. — Reagents.  (1)  Standard  salt  solution. 
Dissolve  16.48  grams  of  fused  sodium  chlorid  in  one  liter  of  distilled 
water.  Dilute  100  c.  c.  of  this  stock  solution  to  one  liter  in  order  to 
obtain  a  standard  solution,  each  c.  c.  of  which  contains  .001  gram  of 
chlorin. 

(2)      Silver  nitrate  .solution.     Dissolve  about  2.40  grams  of  silvgr 


848  SANITAEY  ANALYSIS  OF  WATER 

nitrate  crystals  in  one  liter  of  distilled  water.  One  c.  c.  of  this  will 
approximately  equal  .0005  gram  of  chlorin.  Standardize  this  against 
the  standard  salt  solution. 

(3)  Potassium  chromate.  Dissolve  50  grams  of  neutral  potassium 
chromate  in  a  little  distilled  water.  Add  enough  silver  nitrate  to  pro- 
duce a  slight  red  precipitate.  Filter  and  make  up  the  filtrate  to  one 
liter  with  distilled  water. 

(4)  Aluminium  hydrate.  This  is  used  only  to  clarify  the  water 
in  case  of  high  color.  Dissolve  125  grams  of  potash  or  ammonium 
alum  in  one  liter  of  distilled  water.  Precipitate  the  aluminium  hydrate 
by  cautiously  adding  ammonium  hydrate.  Wash  the  precipitate  in  a 
large  jar  by  the  successive  addition  of  distilled  water  and  by  decan- 
tation  until  free  from  chlorin,  nitrites,  and  ammonia. 

Procedure. — For  this  determination  where  the  chlorin  content  is  not 
extremely  low  or  very  high,  titrate  50  c.  c.  of  the  sample  in  a  white  six- 
inch  porcelain  evaporating  dish  with  the  standard  silver  nitrate  solution. 
If  the  chlorin  is  very  high  in  amount,  use  25  c.  c,  or  even  a  smaller 
quantity  if  desired,  diluting  the  volume  taken  with  distilled  water  to 
50  c.  c.  When  the  sample  is  very  low  in  its  chlorin  content,  more  ac- 
curate results  may  be  obtained  by  using  50  c.  c.  of  the  sample  and  add- 
ing, prior  to  titration,  one  c.  c.  of  standard  salt  solution. 

Measure  out  50  c.  c.  of  the  sample  into  the  evaporating  dish.  Into 
another,  measure  50  c.  c.  of  distilled  water.  Add  to  each,  1  c.  c.  of  the 
potassium  chromate  indicator.  To  the  sample  add  carefully  from  the 
buret,  standard  AgNOg  until  the  red  of  the  silver  chromate  persists, 
using  the  distilled  water  for  comparison  of  colors.  Eecord  number  of 
c.  c.  of  the  standard  AgNOg  solution  used. 

Calculation. — One  c.  c.  of  the  silver  nitrate  solution  equals  .0005  gm. 
of  chlorin. 

Assuming  that  50  c.  c.  of  the  sample  requires  5  c.  c.  of  the  stand- 
ard, then  50  c.  c.  of  the  sample  contains  .0005  X  5.  =  .0025  gm.  of  CI. 
or  2.5  mgs.  of  CI. 

1,000  c.  c.  then  would  contain  2.5  X  20  or  50  mgs.  CI. ;  or  50  parts 
per  million. 

In  short,  when  the  standard  silver  solution  equals  just  .0005  gms. 
CL,  the  number  of  c.  c.  used  in  titrating  multiplied  by  10  will  give  the 
parts  per  million. 

OXYGEN 

Oxygen  Consumed. — The  oxygen  consumed  means  the  oxygen  which 
the  organic  compounds  in  water  consume  when  treated  in  an  acid  solu- 
tion with  potassium  permanganate.  The  expression  is  synonymous  with 
"oxygen  required"  or  "oxygen  absorbed."     Oxyjen  consumed  is,  there- 


OXYGEN  849 

fore,  an  index  of  the  amount  of  putrescible  organic  matter  present  and 
should  carefully  be  distinguished  from  the  expression  "dissolved  oxy- 
gen," which  refers  simply  to  the  amount  of  oxygen  held  in  solution  by 
the  water. 

It  is  the  carbon  and  not  the  nitrogen  in  organic  matter  which  is 
oxidized  by  potassium  permanganate  in  an  acid  solution;  hence  this  de- 
termination is  frequently  referred  to  as  an  indication  of  the  carbonaceous 
organic  matter  present.  The  method  indicates  only  a  certain  portion 
of  the  carbon,  and  this  ratio  varies  in  different  samples  of  water.  Fur- 
ther, it  does  not  differentiate  the  carbon  present  in  unstable  organic 
matter  from  that  in  what  might  be  called  fairly  stable  organic  matter, 
such  as  is  sometimes  referred  to  as  "residual  humus."  The  presence 
of  nitrites,  ferrous  iron,  sulphids,  or  other  unoxidized  mineral  com- 
pounds causes  oxygen  to  be  taken  up  and  hence  increases  the  amount 
of  oxygen  consumed  by  this  method.  In  case  such  substances  are  pres- 
ent, a  correction  should  be  made  when  studying  carbonaceous  organic 
matter. 

Determination  of  Oxygen  Consumed. — Reagents.  (1)  Dilute 
sulphuric  acid.  One  part  of  sulphuric  acid  to  three  parts  of  distilled 
water.  This  shall  be  freed  from  oxidizable  matters  by  adding  potas- 
sium permanganate  until  a  faint  pink  color  persists  after  standing 
several  hours. 

(2)  Standard  potassium  permanganate  solution.  Dissolve  0.4  gram 
of  the  crystalline  compound  in  one  liter  of  distilled  water.  Standardize 
against  an  ammonium  oxalate  solution.  One  c.  c.  is  equivalent  to  0.0001 
gram  of  available  oxygen. 

(3)  Ammonium  oxalate  solution.  Dissolve  0.888  gram  of  the 
substance  in  one  liter  of  distilled  water.  One  c,  c.  is  equivalent  to 
0.0001  gram  of  oxygen. 

(4)  Potassium  iodid  solution.    Ten  per  cent  solution  free  of  iodate. 

(5)  Sodium  thiosulphate  solution.  Dissolve  1.0  gram  of  the  pure 
crystallized  salt  in  one  liter  of  distilled  water.  Standardize  against  a 
potassium  permanga-nate  solution  which  has  been  standardized  against 
an  ammonium  oxalate  solution.  As  this  solution  does  not  keep  well, 
determine  its  actual  strength  at  frequent  intervals. 

(6)  Starch  solution.  Mix  a  small  amount  of  clean  starch  with 
cold  water  until  it  becomes  a  thin  paste;  stir  this  into  150  to  200  times 
its  weight  of  boiling  water.  Boil  for  a  few  minutes,  then  sterilize.  It 
may  be  preserved  by  adding  a  few  drops  of  chloroform. 

Procedure. — Measure  into  a  flask  100  c.  c.  of  the  water,  or  a  smaller 
diluted  portion  if  the  water  is  of  high  organic  content.  Add  10  c.  c.  of 
sulphuric  acid  solution  and  10  c.  c.  of  potassium  permanganate  solu- 
tion, and  allow  the  treated  sample  of  water  to  digest  30  minutes  at  boil- 
ing temperature  in  a  water  bath.     Thirty  minutes  is  an  arbitrary  time. 


860  SANITARY  ANALYSIS  OF  WATER 

The  digestion  may  continue  from  5  to  30  minutes;  the  time  used  should 
always  be  stated. 

Precisely  at  the  end  of  the  period  of  digestion  remove  the  flask  and 
add  10  c.  c.  of  the  ammonium  oxalate  solution.  Titrate  with  the  per- 
manganate solution  until  a  faint  but  distinct  color  is  obtained. 

Each  c.  c.  of  the  permanganate  solution  in  excess  of  the  oxalate  solu- 
tion represents  0.0001  gram  of  oxygen  consumed  by  the  sample. 

At  the  end  of  the  period  of  digestion,  if  not  made  at  the  boiling 
temperature,  add  0.5  c.  c.  of  potassium  iodid  solution  to  discharge  the 
pink  color ;  mix ;  titrate  the  liberated  iodin  with  thiosulphate  until  the 
yellow  color  is  nearly  destroyed;  then  add  a  few  drops  of  starch  solution 
and  continue  titration  until  the  blue  color  is  just  discharged. 

Should  the  volume  of  permanganate  solution  be  insufficient  for  com- 
plete oxidation,  repeat  the  analysis,  using  a  larger  volume,  so  that  at 
least  three  c.  c.  of  the  permanganate  solution  will  be  present  in  excess 
when  the  ammonium  oxalate  solution  is  added. 

When  unoxidized  mineral  substances,  such  as  ferrous  sulphate,  sul^ 
phids,  nitrites,  etc.,  are  present  in  the  sample,  corrections  should  be 
applied  as  accurately  as  possible  by  procedures  suitable  for  the  samples 
being  analyzed.  Direct  titration  of  the  acidified  sample  in  the  cold, 
using  a  three-minute  period  of  digestion,  serves  this  purpose  quite  well 
for  polluted  surface  waters  and  fairly  well  for  purified  sewage  effluents. 
Raw  sewages  containing  no  trade  wastes  seldom  need  such  a  correction, 
but  when  raw  sewages  contain  "pickling  liquors"  it  is  important.  In 
all  samples  containing  both  unoxidized  mineral  compounds  and  gaseous 
organic  substances  the  latter  should  be  driven  off  by  heat  and  the  sample 
allowed  to  cool  before  applying  this  test  for  the  correction  factor.  Where 
such  corrections  are  necessary  the  fact  should  be  stated,  with  the  amount 
of  correction. 

This  is  one  of  the  oldest  methods  for  determining  organic  matter 
and  has  been  in  very  wide  use  for  more  than  half  a  century.  It  was 
introduced  as  soon  as  the  fact  was  recognized  that  the  loss  on  ignition 
of  the  residue  upon  evaporation  may  indicate  certain  volatile  mineral 
matters,  as  well  as  organic  matter.  To-day  the  method  of  determination 
of  oxygen  consumed  is  ordinarily  not  included  in  a  water  analysis  for 
the  reason  that  the  results  vary  widely,  depending  on  the  procedure 
as  to  certain  details  of  the  method,  and  from  the  further  fact  that  the 
determinations  of  the  organic  matter  in  water  may  be  more  conveniently 
and  satisfactorily  estimated  from  the  free  and  albuminoid  ammonia. 

Dissolved  Oxygen. — Dissolved  oxygen  is  another  expression  for  the 
degree  of  aeration  or  oxygenation  of  water.  It  varies  from  zero  to  sat- 
uration or  slight  supersaturation.  The  amount  of  oxygen  in  solution  is 
fairly  constant  in  waters  of  uniform  composition  freely  exposed  to  the 
air.    Water  containing  sewage  and  other  oxidizable  matters  uses  up  the 


OXYGEN  851 

dissolved  oxygen.  In  badly  polluted  streams  so  much  of  the  dissolved 
oxygen  may  be  lost  in  this  way  that  fish  cannot  breathe.  They  die  from 
suffocation  rather  than  from  the  toxic  effects  of  the  sewage;  fish  must 
have  at  least  2.5  parts  of  oxygen  per  million.  Water  may  contain  prac- 
tically no  oxygen  at  depth  of  40  or  50  feet,  but  deep  soundings  show 
that  aeration  probably  exists  to  greater  depths,  for  fish  and  aerobic 
organisms  live  at  the  bottom  of  the  sea.  In  this  case  the  oxygen  may 
possibly  be  obtained  from  sources  other  than  the  dissolved  oxygen  from 
the  air. 

Dissolved  oxygen  makes  water  sparkling  and  palatable  and  also  helps 
to  consume  the  organic  matter.  Its  absence  permits  the  growth  of  an- 
aerobic organisms  that  cause  putrefaction  and  impart  putrid  tastes  and 
odors  to  the  water.  Pasteur's  original  conception  of  fermentation  was 
decomposition  in  the  absence  of  oxygen. 

The  amount  of  oxygen  found  in  the  water  of  a  running  stream  taken 
at  different  points  may  furnish  valuable  information  as  to  the  rapidity 
with  which  the  process  of  self-purification  is  taking  place  from  a  chemir 
cal  standpoint. 

The  amount  of  oxygen  dissolved  in  a  water  may  be  measured  by 
three  methods :  viz.,  that  of  Winkler,  Thresh,  or  Levy.  The  method  of 
Winkler  is  generally  used  in  this  country  and  possesses  the  advantage  of 
requiring  only  simple  and  not  readily  breakable  apparatus.  It  is  there- 
fore recommended  as  the  standard  method. 

Method. — To  determine  the  amount  of  dissolved  oxygen  it  is  neces- 
sary to  collect  the  sample  with  extreme  care  in  order  to  avoid  the  en- 
trainment  of  any  oxygen  from  the  atmosphere.  The  sample  bottles 
should  be  glass-stoppered,  with  a  narrow  neck,  holding  at  least  250  c.  c. 
The  exact  capacity  of  the  bottle  must  be  determined.  The  bottle  should 
be  filled  through  a  glass  or  rubber  tube  which  reaches  to  the  bottom  of 
the  bottle,  and  the  water  allowed  to  overflow  for  several  minutes,  after 
which  the  glass  stopper  is  carefully  replaced,  so  that  no  bubble  of  air 
is  caught  beneath  it. 

The  method  depends  upon  the  fact  that  manganous  sulphate  in  alka- 
line solution  is  oxidized  to  a  manganate  in  the  presence  of  oxygen  in 
solution  in  water.  On  neutralization  with  sulphuric  acid  the  man- 
ganese tends  to  revert  to  the  manganous  sulphate  with  the  liberation  of 
oxygen,  and  if  potassiuin  iodid  is  present  this  is  decomposed  by  the  liber- 
ated oxygen,  setting  free  iodin.  The  liberated  iodin  is  titrated  with 
sodium  thiosulphate,  the  end  point  being  made  more  definite  by  the 
use  of  starch  paste,  which  is  added  near  the  end  of  the  titration. 


853  SANITAEY  ANALYSIS  OF  WATER 


IRON 

Iron  in  water  influences  its  quality  from  the  standpoint  of  desira- 
bility rather  than  from  the  standpoint  of  health.  After  hardness  there 
is  no  question  of  greater  practical  importance  in  considering  the  quality 
of  a  water.  All  natural  waters  contain  a  certain  amount  of  iron,  and 
ground  waters  are  apt  to  contain  it  in  objectionable  amounts.  Appre- 
ciable amounts  of  iron  render  water  unsuitable  for  domestic  and  techni- 
cal purposes;  it  stains  clothes  in  the  laundry,  and  is  apt  to  cause  head- 
ache and  constipation  if  used  habitually  for  drinking. 

When  iron  is  present  in  water  it  supports  a  fungus  (Crenotlirix 
Jcuehniana),  an  organism  which  may  grow  in  the  pipes  in  sufficient 
amount  to  obstruct  the  flow  of  water  or  even  completely  choke  the  pipe. 
It  is  chiefly  troublesome  in  ground  waters  containing  organic  matter  and 
iron.  This  was  the  cause  of  the  complete  obstruction  of  the  water  pipes 
in  the  New  York  Custom  House  in  1907.  The  same  sometimes  occurs 
in  the  pipes  of  driven  wells. 

Iron  is  very  widely  distributed  and  exists  in  practically  all  sands, 
gravels,  soils,  and  rocks  with  which  water  comes  in  contact.  The  solu- 
tion of  the  iron  is  brought  about  by  the  organic  matter.  The  iron  exists 
in  the  soil  as  ferric  compounds.  These  are  reduced  by  the  organic  mat- 
ter to  ferrous  salts,  which  are  soluble  in  water  containing  carbonic  acid. 
Trouble  from  iron  is  always  to  be  expected  when  there  is  an  excess  of 
organic  matter  in  the  material  through  which  the  water  passes.  In  a 
well-drained,  pervious  soil  the  oxygen  from  the  air  circulates  in  the 
pores  of  the  soil  and  furnishes  what  is  required  for  the  oxidation  of  the 
organic  matter.  Iron  is  not  dissolved  under  these  conditions,  even  in 
the  presence  of  large  amounts  of  organic  matter,  but  if  the  air  supply 
is  cut  off,  as  for  instance  in  case  the  pores  of  the  soil  are  filled  with 
water,  the  solution  of  iron  is  sure  to  take  place.  The  iron  is  dissolved 
in  the  form  of  ferrous  salts,  usually  ferrous  carbonate.  When  ground 
waters  containing  iron  are  first  drawn  they  look  clear,  but  the  ferrous 
salts  in  solution  are  soon  oxidized  on  contact  with  the  air  to  insoluble 
ferric  salts,  which  are  precipitated  as  red  oxids. 

Iron  Pipes. — Nearly  all  waters  attack  iron  pipes,  corroding  them  and 
forming  tubercles  on  the  inner  surface.  This  is  objectionable,  be- 
cause it  reduces  the  carrying  capacity  of  the  pipe  and  also  influences 
the  quality  of  the  water. 

Tubercles  are  formed  as  follows:  The  organic  matter  in  the  water 
settles  in  the  pipe  and  attacks  the  iron  through  a  blow  hole  or  other 
minute  opening  in  the  coating.  The  organic  matter  decomposes,  form- 
ing carbon  dioxid,  which  acts  upon  the  iron,  causing  some  of  it  to  go 
into  solution  as  ferrous  carbonate.     The  soluble  ferrous  carbonate  for 


lEON  853 

the  most  part  passes  on  in  the  flowing  water,  but  some  of  it  becomes 
oxidized  by  the  oxygen  in  the  flowing  water  and  is  precipitated  as  the 
insoluble  ferric  carbonate  and  remains  at  the  surface  of  the  deposit. 
The  iron  precipitated  in  this  way  acts  as  a  coagulant  upon  the  organic 
matter  in  the  flowing  water  at  the  point  where  the  iron  is  precipitated. 
It  thus  attracts  the  organic  matter  from  the  flowing  water  and  binds  it 
to  that  previously  deposited  into  a  firm,  compact,  but  porous  mass,  and 
this  mass  is  the  beginning  of  a  tubercle.  The  process  is  continuous, 
though  slow.  Many  years  may  elapse  before  the  tubercle  reaches  the 
height  of  an  inch.  Tuberculation  starts  more  freely  and  progresses 
more  rapidly  in  waters  from  rivers  or  reservoirs  containing  suspended 
organic  matter.  It  is  less  troublesome  with  filtered  waters^  and  with  lake 
waters  relatively  free,  from  such  suspended  matter.  Tuberculation  may 
be  prevented  by  improving  the  quality  of  the  water  or  by  thoroughly 
coating  the  inside  of  the  pipes  with  asphaltum  or  tar.  Cement-lined 
pipes  are  not  subject  to  tuberculation,  but  have  defects  in  other  particu- 
lars. When  the  process  has  advanced  far  it  may  be  corrected  by  pipe 
scrapers.  They  consist  of  appliances  driven  by  the  water  pressure 
through  the  pipes,  with  arrangements  to  scrape  oflE  the  tubercles.  This 
temporarily  restores  the  original  carrying  capacity  of  the  pipe,  but  the 
process  must  be  repeated  at  intervals.  It  has  the  disadvantage  of  also 
scraping  off  a  large  part  of  the  tar  coating  and  leaving  the  iron  of 
the  pipe  exposed  to  the  action  of  water  to  a  much  greater  extent. 
(Hazen.) 

Water  that  passes  through  the  water-backs  of  the  kitchen  stove  to 
the  hot-water  tank  is  particularly  likely  to  collect  iron,  which  accumu- 
lates at  the  bottom  of  the  hot-water  tank.  This  deposit  may  accumulate 
for  days  and  even  weeks  until  some  unusual  draught  of  water  or  other 
disturbance  occurs — perhaps  on  washing  day — causes  a  stirring  up  of  the 
iron  precipitate.    When  this  happens  it  is  very  objectionable. 

The  household  filter  is  the  most  convenient  and  satisfactory  means 
of  removing  iron  deposits  from  water  that  is  otherwise  good.  The  re- 
moval of  iron  from  a  city's  water  supply  is  a  distinct  process  rarely 
combined  with  purification.  In  most  cases  iron  may  be  removed  by 
thoroughly  aerating  the  water  in  order  to  drive  off  the  excess  of  CO, 
and  in  order  to  introduce  oxygen  necessary  to  oxidize  the  iron  from  the 
soluble  ferrous  state,  in  which  it  exists,  to  the  insoluble  ferric  state. 
The  precipitated  ferric  salts  can  then  be  removed  by  sedimentation  or, 
better,  by  filtration. 

LEAD 

Tests. — The  presence  of  lead  may  be  discovered  by  chemical  tests  or 
surmised  from  the  symptoms  of  lead  poisoning  among  those  who  use 


854 


SANITAEY  ANALYSIS  OF  WATEK 


the  water.  In  the  amounts  present  it  does  not  affect  either  the  appear- 
ance or  taste  of  the  water. 

It  is  possible  to  determine  the  presence  of  lead  in  clear  water  and 
roughly  estimate  its  amount  by  acidifying  with  acetic  acid,  saturating 
with  hydrogen  sulphid  and  comparing  the  brown  tint  produced  with 
that  produced  by  standard  lead  solutions  contained  in  Nessler  tubes  simi- 
lar to  those  for  containing  the  sample  under  examination.  This  method 
is  not  applicable  if  the  water  is  colored  or  contains  iron — in  this  case 
special  analytical  procedures  are  necessary. 

The  sample  of  water  used  for  testing  lead  should  be  the  first  portion 
(a  pint  or  less)  drawn  after  standing  at  least  one  hour  in  the  pipes. 

No  water  should  be  used  for  drinking  purposes  containing  even  a 
trace  of  lead,  for,  however  minute  it  is,  its  presence  in  the  water  indi- 
cates danger.  Very  often  the  samjDle  examined  will  not  represent  the 
daily  maximum.    For  lead  poisoning  and  its  relation  to  water  see  p.  920. 


EXPRESSION  OF  CHEMICAL  RESULTS 


Formerly  results  were  expressed  in  grains  per  gallon.  After  the 
introduction  of  the  metric  system  results  were  expressed  in  parts  per 
100,000,  but  now  results  are  commonly  expressed  in  parts  per  million. 
The  latter  method  has  the  advantage  that  1  inilligram  is  .000,001  liter, 
and,  therefore,  1  milligram  in  1,000  c.  c.  =  1  part  per  million.  A  liter 
or  a  fraction  thereof  of  the  water  to  be  analyzed  is  used,  which  greatly 
simplifies  the  calculations. 

Of  course,  the  assumption  is  made  that  a  liter  of  water  weighs  a 
kilogram.  This  is  sufficiently  accurate  for  potable  waters,  but  intro- 
duces an  error  where  mineral  waters  are  dealt  with  whose  specific  gravi- 
ties are  appreciably  higher  than  unity.  In  such  cases  the  water  may  be 
actually  weighed,  or  else  the  weight  may  be  estimated  from  the  known 
specific  gravity  and  volume. 

The  results  expressed  in  parts  per  100,000  or  in  grains  per  gallon 
may  be  transformed  to  parts  per  million,  or,  conversely,  by  the  use  of 
the  following  table : 


Grains 

U.  S.^Gal- 
lon 

Grains 

per 
Imperial 
Gallon 

Parts  per 
100,000 

Parts  per 
1,000,000 

1  grain  per  U.  S.  gallon 

1  grain  per  Imperial  gallon 

1  part  per  100,000 

1.000 
0.835 
0.585 
0.058 

1.20 
1.00 
0.70 
0.07 

1.71 
1.43 
1.00 
0.10 

17.1 
14.3 
10.0 

1  part  per  1,000,000 

1.0 

CHAPTEE  III 
MICROSCOPICAL  EXAMINATION  OF  WATER 

The  chief  object  of  the  microscopic  examination  of  water  is  the  de- 
termination of  the  presence  or  absence  of  those  microorganisms  which 
produce  objectionable  tastes  and  odors.  In  certain  cases  the  determina- 
tion is  also  of  value  as  an  index  of  pollution  or  as  a  guide  to  the  iden- 
tity of  the  water.  The  microscopical  organisms  comprise  the  Dia- 
tomaceae,  Chlorophyceae,  Cyanophyceae,  Fungi,  Protozoa,  Eotifera,  Crus- 
taceae  and  other  organisms  minute  in  size,  but  not  including  the  bacteria. 
Fragments  of  organic  matter,  broken-down  organisms,  zooglea,  etc., 
should  be  termed  amorphous  matter.  Clay,  silt,  oxid  of  iron,  and  mineral 
matter  in  general  are  not  included  under  amorphous  matter  and  are  not 
measured  by  microscopic  examination. 

The  term  "microorganisms"  as  used  by  the  water  analyst  includes 
all  organisms,  whether  plant  or  animal,  that  are  invisible  or  barely 
visible  to  the  naked  eye,  other  than  bacteria.  The  bacteria  are  set  apart, 
inasmuch  as  their  significance  and  the  naethod  of  studying  them  are  dif- 
ferent from  all  other  microscopic  organisms.  As  Whipple  aptly  phrases 
it,  "Bacteria  make  a  water  unsafe,  microorganisms  make  it  unsavory." 

The  sanitary  quality  of  water  cannot  be  definitely  shown  from  a 
microscopical  examination.  Surface  waters  are  usually  rich  in  micro- 
scopic life,  while  ground  waters  are  comparatively  free.  However,  as 
soon  as  ground  waters  stand  in  pipes  or  are  exposed  to  the  light,  micro- 
scopic organisms  develop. 

"Plankton"  is  the  general  name  given  to  the  microscopic  aggrega- 
tion which  is  investigated  in  any  given  sample  of  water.  The  term  as 
used  embraces  plants  and  animals  that  float  about  in  the  free  state,  also 
larvae,  egg  masses,  etc.,  of  higher  ajiimals.  It  includes  diatoms,  algae, 
fungi,  protozoa,  etc. 

For  a  full  discussion  of  this  subject  see  "The  Microscopy  of  Drinking 
Water,"  by  George  C,  Whipple.    John  Wiley  &  Sons,  N.  Y.,  1914. 

The  Sedgwick-Rafter  Method. — This  is  the  standard  method  for 
counting  the  number  of  microscopic  organisms  in  water.  It  consists  in 
collecting  the  microscopic  particles  suspended  in  a  known  quantity  of 
water,  and  counting  them  in  a  cell  of  known  capacity. under  the  micro- 
scope. The  microscopic  particles  are  collected  upon  sand  by  filtration. 
This  is  done  in  a  straight-sided  cylindrical  funnel,  shaped  and  graduated 
as  shown  in  figure  106. 

855 


856 


MICROSCOPICAL  EXAMINATION  OF  WATER 


Moisten  a  disk  of  bolting  cloth  and  place  it  over  the  small  end  of  the 
rubber  stopper  and  press  it  tightly  into  the  lower  end  of  the  funnel. 
Now  pour  sand  on  to  the  bolting  cloth,  to  the  depth  of  about  1  cm. 
Quartz  sand  or  white  alundum  may  be  used,  but  it  should  first  be  washed 
and  ignited;  and  of  such  size  that  it  will  pass  through  a  sieve  having 
60  meshes  to  the  square  inch,  but  will  not  pass  a  100 
mesh  sieve.  Sand  between  120  and  140  meshes  may 
be  used  if  the  water  contains  very  small  microorgan- 
isms. Now  run  250  c.  c.  of  the  water  to  be  examined 
into  the  funnel  without  disturbing  the  sand.  Filtra- 
tion may  be  hastened  either  by  pressure  from  above 
or  suction  from  below;  if  the  water  filters  too  slowly 
errors  will  result  from  many  of  the  microorganisms 
sticking  to  the  sides  of  the  funnel.  When  practically 
all  the  water  has  passed  off,  and  the  sand  begins  to 
dry,  hold  the  funnel  in  the  left  hand  and  slope  it  so 
that  the  sand  falls  away  from  the  stopper;  remove 
the  stopper  and  quickly  slip  a  test  tube  over  the  end 
of  the  funnel  and  allow  the  sand  to  flow  into  it. 
Without  removing  the  test  tube,  wash  the  funnel  with 
5  c.  c.  of  distilled  water.  The  mixture  of  sand, 
microorganisms  and  water  in  the  test  tube  is  agi- 
tated, and  the  supernatant  suspension  decanted  into 
a  second  tube  from  which  1  c.  c,  is  placed  into  the 
counting  cell  of  that  capacity.  Slip  the  cover  glass 
into  place  and  count  the  microorganisms  with  a  spe- 
cially ruled  ocular  micrometer  and  a  2/3-inch  ob- 
jective. 

The  counting  cell  consists  of  a  rectangular  brass 
rim  cemented  to  an  ordinary  glass  slide.  The  inside 
dimensions  of  the  rim  are  50  mm.  x  20  mm.  by  1 
mm.,  making  a  capacity  of  one  cubic  centimeter. 
The  roof  of  the  cell  consists  of  a  cover  glass  (No.  3) 
of  sufficient  size. 

The  ocular  micrometer  is  so  ruled  that  the  largest 
square  is  1  square  millimeter;  the  smallest  square  is 
1  standard  unit.  The  area  which  the  largest  square 
covers  on  the  stage  of  the  microscope  should  be  measured  with  a  stage 
micrometer  and  adjusted  by  changing  the  length  of  the  draw  tube  of  the 
microscope  so  that  this  large  square  will  measure  just  1  square  milli- 
meter. A  rough  and  ready  ocular  micrometer  can  be  made  by  cutting 
out  a  circle  of  cardboard  which  will  fit  into  the  tube  of  the  microscope, 
this  circle  of  cardboard  having  a  square  cut  in  its  center,  the  size  of  the 
square  to  be  the  largest  which  the  diaphragm  will  allow.     It  will  be 


cc 

100 

— 

ISO 

400 

— 

tso 

300 

— 

no 

100 

— 

ItO 
100 

- 

so 

\ " 

/ 

Fig.  106.  —  Gradu- 
ated Cylindri- 
cal Funnel  and 
Concentrating 
Attachment 
Used  in  the  Sedg- 
wick-Rafter 
Method. 


MICEOSCOPICAL  EXAMINATION  OF  WATER  857 

found  that  the  area  of  the  stage  which  will  be  included  in  the  field  will 
be  approximately  1  square  millimeter. 

Recording  Results. — Twenty  full  squares  of  1  mm.  each  are  counted 
at  random,  the  organisms  identified,  and  the  results  calculated  either 
by  the  number  of  organisms  per  cubic  centimeter  of  the  sample,  or, 
better  perhaps,  the  number  of  standard  units  per  cubic  centimeter  of 
the  sample. 

The  number  of  organisms  per  cubic  centimeter  may  be  determined 
from  the  following  equation : 

1000  W 

Number  per  cubic  centimeter  = 

NF 
W  =  the  number  of  cubic  centimeters  of  water  used  in  washing  the  sand. 
N  =  the  number  of  squares  counted. 
F  =  the  number  of  cubic  centimeters  of  water  filtered. 

The  standard  unit  is  an  attempt  to  measure  the  mass  rather  than 
the  number  of  microscopic  organisms  present  in  the  water.  By  this 
means  a  rough  estimation  of  the  amount  of  suspended  organic  matter 
is  obtained.  Whipple,  who  devised  the  standard  unit  method  of  counting 
microorganisms,  defines  the  standard  unit  as  a  square  20  x  20  microns  = 
400  square  microns.    A  micron  is  0.001  millimeter. 

The  ocular  micrometer  used  corresponds  to  this  standard  unit.  A 
square  which  covers  1  square  millimeter  on  the  stage  of  the  microscope 
is  divided  into  four  equal  squares.  Each  of  these  is  subdivided  into 
25  equal  squares.  Each  of  these  contains  25  standard  units.  The  eye 
can  easily  divide  the  side  of  the  smallest  squares  into  fifths,  and  each  of 
these  fifths  is  the  size  of  a  standard  unit. 

Significance  of  the  Examination. — The  microscopical  examination  of 
water  is  of  great  value  in  supplementing  the  chemical  and  bacterial 
analyses.  It  may  explain  the  cause  of  odors  and  tastes  in  a  water;  it 
may  explain  certain  chemical  determinations,  as  albuminoid  ammonia, 
dissolved  oxygen,  oxygen  consumed,  carbon  dioxid,  etc. ;  it  may  indicate 
sewage  contamination;  it  may  suggest  the  state  of  self-purification  of 
a  polluted  water;  it  may  identify  the  source  of  the  water. 

Several  of  the  microscopic  organisms,  when  present  in  sufficient  quan- 
tities, give  rise  to  objectionable  odors  and  tastes,  either  when  in  a  vege- 
tative state  or  upon  decomposition.  The  natural  odors  of  organisms  are 
due  to  oils  analogous  to  the  essential  oils  as  in  peppermint  and  in  cer- 
tain fishes.  In  general,  the  diatoms  have  an  aromatic  odor,  increasing 
to  that  of  a  geranium  leaf,  and  even  to  an  intensity  that  is  fishy.  The 
cyanophyceae,  or  blue-green  algae,  have  a  grassy  or  moldy  odor.  The 
chlorophyceae  have  little  odor,  although  some  of  the  motile  forms  give 
rise  to  faintly  fishy  odors.     The  ciliated  protozoa  have  in  general  no 


858  MICEOSCOPICAL  EXAMINATION  OF  WATEE 

odor.  Uroglena,  synura,  dinobryon,  and  peridinium  may  and  often  do 
give  rise  to  fishy  odors.  Of  the  other  microorganisms,  the  rotifera  and 
Crustacea,  no  forms  have  been  recorded  as  giving  rise  to  objectionable 
odors.  These  forms  are  present  only  when  there  are  lower  forms  upon 
which  to  feed.  They  are  scavengers  and  as  such  may  be  considered 
as  desirable  elements  in  water.  Their  presence,  however,  calls  for 
an  investigation  of  the  nature  of  their  food  supply,  as  it  is  often  fur- 
nished by  pollution.     This  does  not  necessarily  hold  true  in  all  cases. 

Besides  these  animal  and  plant  forms  there  may  be  present  also 
sponges,  mosses,  yeasts,  and  molds,  the  significance  of  which  is  varied 
and  dependent  upon  local  conditions. 

There  are  many  sources  of  error  in  a  quantitative  determination  of 
the  microscopic  organisms  in  water.  Some  of  the  organisms  stick  to 
the  sides  of  the  funnel ;  some  pass  through  the  sand ;  some  are  so  heavy 
they  settle  in  the  sample,  especially  if  it  has  been  allowed  to  stand;  some 
are  so  fragile  that  they  disintegrate  readily,  and  further  error  may  be 
due  to  unequal  distribution  of  the  organisms  in  the  counting  cell.  For 
all  these  reasons  accurate  results  -uathin  10  per  cent,  are  not  possible, 
and  comparative  results  may  only  be  obtained  by  careful  standardization 
of  methods. 

THE  BACTERIOLOGICAL  EXAMINATION 

Practically  all  natural  waters  contain  bacteria.  This  is  true  of  rain 
water,  ground  water,  and  the  waters  of  lakes,  rivers,  and  oceans.  The 
number  and  variety  of  the  bacteria  vary  greatly  in  different  places  and 
under  different  conditions.  The  bacteria  are  washed  into  the  water  from 
the  air,  from  the  soil,  and  from  almost  every  conceivable  object.  The 
intestinal  contents  of  animals  pollute  waters  with  enormous  numbers, 
of  microorganisms,  but  it  is  the  infection  with  certain  species  from  man 
that  makes  water  most  dangerous  when  consumed  by  his  f  ellowmen. 

TEE  NUMBER  OF  BACTERIA   IN   WATER 

The  number  of  bacteria  is  not  as  important  as  the  kind,  yet  much 
may  be  learned  from  a  simple  enumeration  of  the  bacteria.  Eoughly 
speaking,  the  number  of  bacteria  in  water  corresponds  to  the  amount 
of  organic  pollution.  No  known  method  furnishes  a  complete  census 
of  the  bacterial  population  of  a  given  sample  of  water.  Methods  based 
upon  the  direct  microscopic  count  of  the  bacteria  do  not  distinguish  be- 
tween the  live  and  the  dead  ones ;  further,  only  those  that  may  readily 
be  seen  by  simple  methods  are  thus  visible.  Many  bacteria,  especially 
those  pathogenic  for  man,  do  not  vegetate  at  20°  C,  so  that  the  usual 
pounts  upon  gelatin  may  vary  greatly  from  those  obtained  upon  agar 


THE  BACTEEIOLOGICAL  EXAMINATION  859 

at  37°  C.  Some  varieties  require  acid,  others  alkaline  media;  some  are 
aerobic,  others  anaerobic ;  some  will  not  grow  unless  the  medium  contains 
blood  or  other  suitable  pabulum,  and  so  on  through  a  wide  gamut  of 
conditions. 

Although  it  is  not  possible  to  determine  the  total  number,  inferences 
of  importance  may  be  drawn  from  the  diiferences  in  the  numbers  of 
bacteria  in  a  given  water  obtained  by  different  methods.  Thus  a  water 
containing  great  numbers  of  bacteria,  when  counted  upon  gelatin  at 
20°  C,  and  but  few  colonies  upon  agar  at  37°  C,  has  little  sanitary 
significance,  whereas  a  water  containing  few  bacteria,  but  most  of  them 
varieties  that  grow  upon  agar  at  37°  C,  with  relatively  few  at  20°  C, 
must  be  looked  upon  with  suspicion.  The  distinction  between  polluted 
waters  and  waters  of  good  quality  is  more  sharply  marked  by  counts  at 
37°  C.  than  is  the  case  with  counts  at  20°  C.  Another  advantage  of 
growing  the  plates  at  a  higher  temperature  is  that  the  results  are  avail- 
able in  a  much  shorter  time. 

The  number  of  bacteria  which  grow  at  40°  C  are  of  special  value, 
since  this  class  includes  the  typhoid  bacillus  and  other  water-borne 
pathogens,  but  excludes  the  common  water  bacteria  of  little  sanitary  im- 
portance. The  significance  of  acid-producing  bacteria  which  grow  at 
40°  C.  upon  litmus  lactose  agar  is  a  well-known  method  in  differentiating 
and  determining  the  number  of  organisms  belonging  to  the  colon  type 
in  a  water. 

From  Germany  we  have  the  arbitrary  standard  based  upon  the  dic- 
tum of  Koch  that  a  good  water  should  not  contain  over  100  bacteria 
per  c.  e.  This  is  a  good  working  rule,  but  should  not  be  taken  too  liter- 
ally. Thus,  water  may  contain  great  numbers  of  the  common  aquatic 
bacteria  which  vegetate  at  room  temperature  and  which  are  not  harmful 
to  man.  Surface  waters  contain  the  greatest  numbers  on  account  of 
exposure  to  contamination  to  which  they  are  liable ;  rain  waters  contain 
comparatively  few,  excepting  the  first  shower  through  a  very  dusty  at- 
mosphere; ground  waters  from  the  depths  are  practically  sterile.  Un- 
polluted shallow  well  waters  are  also  exceptionally  free.  The  number 
and  significance  of  the  bacteria,  therefore,  vary  with  the  source  of  the 
water.  For  example,  a  hundred  bacteria,  including  a  few  colon  bacilli, 
in  a  well  water  would  be  regarded  with  great  suspicion,  whereas  a  hun- 
dred or  more  bacteria,  with  an  occasional  colon  bacillus,  in  a  river  water 
draining  an  uninhabited  watershed  would  be  normal. 

The  number  of  bacteria  in  water  depends  somewhat  upon  the  man- 
ner in  which  it  is  stored.  Thus  a  water  containing  a  few  organisms 
placed  in  a  closed  bottle  and  kept  at  room  temperature  may,  at  the  end 
of  24  hours,  contain  hundreds  or  thousands  per  c.  c.  I  once  examined 
a  deep  well  water  that  was  practically  sterile  as  it  came  out  of  the  earth, 
but  when  stored  in  a  cistern  gave  over  a  thovisand  organisms  per  c.  c. 


860  MICEOSCOPICAL  EXAMINATION  OF  WATER 

These  came  from  the  multiplication  of  the  bacteria  that  entered  the 
water  from  the  air,  dust,  leaves,  and  other  sources.  On  the  other  hand, 
water  stored  in  impounding  reservoirs  shows  a  marked  diminution  in 
the  number  of  bacteria. 

The  numerical  determination  of  bacteria  in  water  is  of  very  great 
value  when  studying  surface  waters,  such  as  lakes  and  rivers.  As  a 
rule,  the  number  of  bacteria  is  proportional  to  the  pollution  of  a  river — 
not  necessarily  fecal  pollution,  but  pollution  from  dead  organic  matter 
of  one  kind  or  another.  The  bacterial  content  of  a  river  water  varies 
sharply  from  time  to  time.  Contrary  to  the  usual  opinion,  a  river  con- 
tains more  bacteria  in  the  winter  time  than  in  the  warm  weather.  Dur- 
ing times  of  freshets  or  turbidity  the  number  of  bacteria  will  rise  very 
abruptly.  In  other  words,  the  number  of  bacteria  in  a  stream  is  an 
index  of  its  turbidity.  It  is  an  interesting  fact  that  in  the  Potomac  and 
other  rivers  the  bacterial  curve  does  not  correspond  to  the  typhoid  fever 
curve.  Typhoid  in  Washington  is  highest  in  summer,  but  the  bacteria 
are  most  numerous  in  winter.  While  sudden  variations  in  the  number 
of  bacteria  have  a  ready  explanation  in  the  case  of  turbid  and  torrential 
rivers,  in  the  case  of  lakes,  and  especially  in  a  ground  water,  variation 
in  numbers  indicates  nearby  sources  of  pollution  and  is  a  danger  signal. 
Eor  shallow  wells  the  interpretation  of  numbers  is  not  so  easy,  largely 
because  infection  may  enter  at  the  surface.  Wells  which  are  poorly  pro- 
tected at  the  top  will  always  show  an  unusually  large  number  and  variety 
of  bacteria. 

Numerical  determination  is  also  of  importance  in  tracing  imperfec- 
tions and  leaks  in  a  water  supply.  Thus  Dr.  Shuttleworth,  of  Toronto, 
was  able  through  this  means  to  suspect  a  broken  water  main,  and  upon 
examination  it  was  found  that  a  whole  section  of  the  conduit  had  dropped 
out  of  place,  so  that  the  supply  was  being  taken  from  the  lake  near  the 
shore  instead  of  some  distance  away  where  the  intake  was  located. 

The  great  value  of  the  numerical  estimate  of  bacteria  is  well  known 
in  determining  the  efficiency  of  filters. 

Method  for  Determining  the  Number  of  Bacteria  in  Water. — The 
standard  medium  for  determining  the  number  of  bacteria  in  water  is  a 
nutrient  agar  having  a  reaction  of  -|-1  per  cent.,  using  phenolphthalein 
as  an  indicator.  The  agar  is  made  by  using  distilled  water  and  an  in- 
fusion of  fresh  lean  meat,  and  not  meat  extract.  The  medium  contains 
1  per  cent,  of  Witte's  peptone  and  1  per  cent,  of  agar. 

The  sample  of  water  must  be  shaken  vigorously  at  least  25  times 
in  order  to  break  up  the  bacterial  clusters  and  to  obtain  a  uniform  sus- 
pension. If  the  water  contains  less  than  200  bacteria  per  c.  c,  1  c.  c.  of 
it  may  be  placed  directly  in  the  petri  dish,  then  add  10  c.  c.  of  the 
standard  medium.  Mix  well,  congeal,  and  incubate  at  37°  C.  for  48 
hours  in  a  dark,  well- ventilated  incubator  where  the  atmosphere  is  prac- 


THE  BACTERIOLOGICAL  EXAMINATION  861 

tically  saturated  with  moisture.  When  gelatin  is  used  the  plates  should 
be  incubated  at  20°  C.  for  4  days.  If  there  is  reason  to  believe  that  the 
number  of  bacteria  is  more  than  200  per  c.  c,  dilute  by  mixing  1  c.  c. 
of  the  sample  with  9  c.  c,  of  sterilized  tap  or  distilled  water.  Again 
shake  25  times  and  plate  1  c.  c.  of  the  dilution.  Higher  dilutions  may 
be  made  in  99  c.  c.  and  so  on.  In  the  case  of  an  unknown  water  or 
sewage  it  is  customary  to  use  several  dilutions  of  the  same  sample.  Count 
the  colonies  upon  a  Wolffluegel  apparatus  or  a  Jeff er's  plate.  A  successful 
plate  should  contain  not  more  than  200  colonies.  The  whole  number 
of  colonies  on  a  plate  should  be  counted,  the  practice  of  counting  a 
fractional  part  being  resorted  to  only  in  cases  of  necessity. 

When  agar  is  used  for  plating  it  will  be  found  advantageous  to  use 
petri  dishes  with  porous  earthenware  covers  in  order  to  avoid  the  spread- 
ing of  colonies  by  the  water  of  condensation. 

In  order  to  avoid  fictitious  accuracy  and  yet  express  the  numerical 
results  by  a  method  consistent  with  the  precision  of  the  work,  the  table 
below  should  be  followed  in  expressing  the  numbers  of  bacteria  per  c.  c. : 

From 


1   to 

50 

recorded  as 

found 

51    " 

100 

a 

to  the  nearest 

5 

101     « 

250 

u 

u 

u 

u 

10 

251    " 

500 

u 

a 

u 

« 

25 

501     " 

1,000 

u 

a 

u 

u 

50 

1,001     " 

10,000 

a 

a 

u 

u 

100 

10,001     " 

50,000 

a 

a 

u 

u 

500 

50,001     " 

100,000 

li 

ti 

u 

a 

1,000 

100,001     « 

500,000 

u 

a 

a 

u 

10,000 

500,001     « 

1,000,000 

u 

ft 

« 

u 

50,000 

1,000,001     " 

10,000,000 

u 

u 

u 

u 

100,000 

KINDS 

OF  BACTERIA 

•  1        •      p                          r 

IN 

WATER 

Water  analysis  is  in  its  infancy  so  far  as  methods  for  determining 
the  kinds  of  bacteria  are  concerned.  It  is  comparatively  easy  to  isolate 
colon  bacilli  and  to  determine  their  approximate  number  in  a  water. 
It  is  also  comparatively  easy  to  isolate  cholera  vibrio.  Methods  for  de- 
termining whether  a  water  does  or  does  not  contain  typhoid,  dysentery, 
and  other  pathogenic  parasites  are  tedious,  difficult,  and  often  impossible 
in  the  present  state  of  our  knowledge. 

A  certain  amount  of  information  may  be  gleaned  from  the  presence 
and  number  of  organisms  belonging  to  certain  groups,  such  as  chromo- 
genic,  liquefying,  and  fermenting  types.  Chromogenic  organisms  exist 
everywhere  in  surface  waters.  They  should  be  practically  absent  from 
ground  waters.  The  same  is  true  of  organisms  that  are  able  to  liquefy 
gelatin  and  ferment  sugars.  The  chromogenic,  proteolytic  and  ferment- 
ing types  are  widespread  in  nature  and  exist  almost  everywhere  in  the 


862  MICROSCOPICAL  EXAMINATION  OF  WATER 

air,  the  soil,  and  in  surface  waters.     Their  presence  in  a  ground  water 
signifies  contamination  or  pollution,   often   from   the  surface. 

The  significance  of  the  various  types  of  bacteria  that  grow  at  dif- 
ferent temperatures  has  already  been  discussed. 

THE    COLON    BACILLUS 

The  colon  bacillus  is  very  widely  distributed  in  nature.  Its  normal 
habitat  may  be  regarded  as  the  intestines  of  man  and  many  other  ani- 
mals. The  colon  bacillus  is  usually  taken  as  an  index  of  pollution. 
The  sanitary  significance  of  colon  bacilli  in  water  varies  with  their 
number  and,  further,  with  their  source.  While  the  colon  bacillus  indi- 
cates pollution,  it  does  not  necessarily  signify  danger,  that  is,  infection. 

By  common  consent  a  ground  water  should  be  condemned  if  it  con- 
tains even  a  few  colon  bacilli,  for  these  organisms  have  no  business  in 
a  soil-filtered  and  properly  protected  well  or  spring  water.  Surface 
waters  are  not  regarded  as  particularly  suspicious,  provided  they  have 
not  more  than  one  colon  bacillus  per  c.  c,  especially  if  the  surface  water 
is  known  to  drain  an  uninhabited  or  controlled  catchment  area.  Many 
of  the  colon  bacilli  in  a  surface  water  come  from  the  droppings  of  wild 
and  domestic  animals  and,  therefore,  are  infinitely  less  indicative  than 
those  that  come  from  the  intestinal  tract  of  man.  The  source  of  the 
colon  bacillus  can  only  be  determined  by  an  inspection  of  the  watershed. 
A  water  containing  10  colon  bacilli  or  more  per  c.  c.  should  be  regarded 
as  grossly  polluted  and  very  likely  to  contain  infection.  Tests  for  the 
colon  bacilli  in  water  must,  therefore,  be  qualitative  and  quantitative. 

The  absence  of  colon  bacilli  in  water  proves  its  harmlessness  so  far 
as  bacteriology  can  prove  it.  It  is  fair  to  assume  that  typhoid  bacilli, 
dysentery  bacilli,  and  other  intestinal  parasites  would  not  be  likely  to 
be  present  in  a  water  in  the  absence  of  the  colon  bacillus.  It  is  possible 
to  conceive  that  in  rare  instances  a  water  may  be  polluted  with  urine 
alone  containing  typhoid  bacilli,  but  no  colon  bacilli. 

Presumptive  Tests  for  the  Colon  Bacillus. — Presumptive  tests  or  par- 
tial tests  are  sometimes  used  to  determine  the  presence  of  B.  coli.  These 
tests  are  fairly  reliable,  and  afford  useful  information.  They  consist, 
as  a  rule,  in  planting  small  quantities  of  the  water  sample  in  lactose 
bile  or  lactose  bouillon  in  fermentation  tubes  and  incubating  at  40°  C. 
Under  these  circumstances  it  may  be  presumed  that  in  the  absence  of 
fermentation  colon  bacilli  are  absent,  and  that  fermentation  with  gas 
production  indicates  their  presence.  Both  these  conclusions  may  be 
misleading.  Grossly  polluted  waters  containing  many  colon  bacilli  may 
be  slow  in  fermenting  sugars  with  the  production  of  gas  on  account  of 
the  preponderance  of  other  more  active  species.  On  the  other  hand, 
many  organisms  other  than  the  colon  bacillus  often  found  in  water 


THE  BACTERIOLOGICAL  EXAMINATION  863 

ferment  sugars  with  gas  production.  It  is  therefore  necessary  to  isolate 
the  suspected  organism  in  pure  culture  and  pass  it  through  the  well- 
known  tests  before  it  is  labeled  B.  coli. 

Qualitative  Methods. — Isolation. — It  is  comparatively  easy  to  iso- 
late the  colon  bacillus  in  pure  culture.  Before  an  organism  is  labeled 
B.  coli  it  should  correspond  to  the  following :  It  should  be  a  relatively 
small,  non-spore-bearing  rod  having  rather  sluggish  or  no  motion;  it 
should  not  liquefy  gelatin;  it  should  ferment  dextrose  broth  with  the 
formation  of  about  50  per  cent,  gas,  one-third  of  which  should  be  carbon 
dioxid  and  two-thirds  hydrogen ;  it  should  coagulate  milk,  with  the  pro- 
duction of  acid  at  37°  C,  but  without  liquefaction  of  the  coagulum. 
This  coagulation  should  occur  either  spontaneously  or  on  boiling;  it 
should  produce  nitrite  and  indol  in  peptone  solution  and  reduce  nitrates. 

To  isolate  B.  coli  the  following  method  is  satisfactory.  Either  plate 
the  water  directly  upon  lactose  litmus  agar  and  fish  the  red  colonies, 
or  plate  directly  upon  Endo's  medium  and  fish  the  red  colonies.  An 
enriching,  and  hence  a  surer,  method,  especially  where  there  are  very 
few  colon  bacilli  in  a  water,  is  first  to  plant  the  water  in  fermentation 
tubes  containing  lactose  or  dextrose  broth,  incubate  at  37°  to  40°  C.  As 
soon  as  gas  production  is  noted  plate  a  small  quantity  of  the  growth 
upon  lactose  litmus  agar  or  Endo's  medium  and  study  the  red  colonies 
for  cultural  and  morphological  characters. 

The  number  of  colon  bacilli  in  a  water  may  be  determined  by  several 
methods : 

(1)  The  Fermentation  Test. — Add  measured  quantities  of  the  water 
sample  to  fermentation  tubes  containing  lactose  broth.  Ordinarily 
0.1,  1.0,  and  10  c.  c.  of  water  are  used  in  this  test.  If  the  water  is 
highly  polluted  smaller  quantities,  such  as  0.01  or  0.001  of  a  cubic  cen- 
timeter, should  be  used.  If  in  such  a  series  fermentation  with  gas  pro- 
duction occurs  in  the  tubes  containing  1  c.  c.  or  more,  but  does  not  take 
place  in  the  tubes  containing  the  smaller  portions,  it  may  then  be  stated 
that  the  water  contains  at  least  one  colon  bacillus  per  cubic  centimeter, 
provided  the  isolation  tests  show  that  the  fermentation  was  caused  by 
this  organism. 

(2)  The  number  of  colon  bacilli  may  be  determined  approximately 
by  planting  the  water  directly  upon  the  surface  of  lactose  litmus  agar  or 
Endo's  medium.  The  fed  colonies  should  then  be  studied  to  determine 
how  many  of  them  are  B.  coli,  and  the  number  may  thus  be  approxi- 
mated per  cubic  centimeter. 

SEWAGE    STREPTOCOCCI 

Fresh  sewage  from  man  and  other  mammalian  animals  usually  con- 
tains streptococci  resembling  the  Streptococcus  pyogenes.     These  intes- 


864  MICEOSCOPICAL  EXAMINATION  OF  WATEE 

tinal  cocci,  which  are  known  as  sewage  streptococci,  grow  more  readily 
than  the  pyogenic  varieties,  and  produce  a  pinkish  colony  on  lactose 
litmus  agar  at  37°  C,  by  which  their  presence  and  number  may  be  de- 
tected in  water.  These  streptococci  are  not  hardy,  and  therefore  when 
found  in  a  water  represent  immediate  pollution.  The  general  consensus 
of  opinion  is  that  the  occurrence  of  these  organisms  in  a  water  is 
of  less  significance  than  B.  coli;  the  streptococcus  test  is  therefore  of 
subordinate  importance. 

TYPHOID    BACILLUS 

The  search  for  a  typhoid  bacillus  in  water  is  frequently  like  looking 
for  a  needle  in  a  haystack.  It  is  probable  that  the  typhoid  bacillus 
rarely,  if  ever,  multiplies  in  natural  waters.  The  dilution  is  usually 
enormous,  and  their  number  is  therefore  comparatively  few.  With 
modern  methods  and  the  use  of  Endo's  medium  it  is  comparatively  easy, 
to  isolate  typhoid  bacilli  from  water  richly  seeded  with  these  organisms, 
but  it  is  practically  a  hopeless  task  to  find  them  when  there  are  only  a 
few  in  a  glassful.  Great  care  must  be  exercised  before  an  organism 
isolated  from  water  is  reported  as  B.  typlwsus.  There  are  many  or- 
ganisms in  water  closely  resembling  typhoid,  some  of  them  even  giving 
pronounced  agglutination  with  specific  serum.  Thus  B.  proteus,  B. 
fiuorescens,  and  even  B.  coli  sometimes  agglutinate  with  typhoid  serum 
and  in  higher  dilutions  than  typhoid  strains  themselves.  An  interesting 
instance  of  this  was  found  in  our  studies  of  the  Potomac  Eiver  water. 
Erost  isolated  an  organism,  the  "Pseudomonas  protea,"  from  the  filtered 
Potomac  Eiver  water  which,  during  the  months  of  August,  September, 
and  October,  1909,  was  more  common  than  B.  coli.  This  organism 
could  not  be  found  in  the  raw  water,  nor  could  it  be  found  in  a  large 
number  of  stools  examined,  which  points  to  a  saprophytic  existence. 
This  organism  may  readily  be  distinguished  from  B.  typhosus,  in  that 
it  has  different  cultural  characters,  and  further  that  animals  injected 
with  cultures  of  Pseudomonas  protea  develop  agglutinins  for  this  or- 
ganism, but  not  for  B.  typhosus. 

CHOLERA 

The  cholera  vibrio  may  be  detected  in  water  by  making  a  Dunham's 
solution  of  the  water  itself;  that  is,  to  a  large  quantity  of  the  water 
sample  add  sufficient  peptone  to  make  a  1  per  cent,  solution,  and  render 
slightly  alkaline  with  sodium  carbonate.  The  water  should  be  placed  in 
Erlenmeyer,  Fernbach,  or  similar  flasks,  presenting  a  large  surface  favor- 
ing aerobic  development.  The  flasks  are  then  placed  in  the  thermostat 
at  37°  C.  and  in  16,  18,  34  hours,  or  longer,  a  loopful  of  the  surface 
growth  is  planted  upon  agar,  Endo's  medium,  or  gelatin.     Cholera  colo- 


THE  BACTEEIOLOGICAL  EXAMINATION  865 

nies  upon  gelatin  have  a  ground-glass  appearance  when  examined  under 
a  low  power  of  the  microscope,  with  irregular  margins,  and  the  gelatin 
is  slowly  liquefied.  Upon  agar  the  colonies  are  not  particularly  distinc- 
tive ;  upon  the  surface  of  Endows  medium  cholera  grows  as  faintly  pinkish, 
moist,  translucent  colonies,  not  unlike  t}^hoid  colonies,  excepting  that 
they  have  slightly  more  color.^  Dependence  cannot  be  placed  upon  the 
appearance  of  the  colonies  nor  upon  the  morphological  characteristics 
of  the  organism.  Suspicious  colonies  should  be  isolated  and  tested  with 
an  agglutinating  serum  of  known  specificity  having  a  high  agglutinating 
value.  All  organisms  that  are  agglutinated  with  this  serum  in  a 
dilution  of  1-1,000  or  over  may  be  regarded  as  cholera.  This,  how- 
ever, should  not  be  accepted  as  final,  for,  as  is  the  case  with  typhoid, 
there  are  numerous  cholera-like  organisms  in  water  that  agglutinate 
with  a  cholera  serum,  but  which  upon  further  study  have  characteris- 
tics which  plainly  show  that  they  are  not  the  organism  which  causes 
cholera.  Einal  dependence  should  be  placed  upon  Pfeiffer's  phenomenon 
and  upon  cross-agglutinating  tests  or  absorption  tests  to  eliminate  the 
phenomenon  of  group  agglutination. 

^See  also  pp.  90,  114  and  118. 


29 


CHAPTEK    IV 
INTEEPEETATION   OF    SANITAEY  WATEE   ANALYSIS 

The  interpretation  of  a  sanitary  water  analysis  is  much  more  diffi- 
cult than  the  analysis  itself,  where  everything  may  be  carried  out  by 
rule  of  thumb  in  accordance  with  standard  procedures.  Single  or  occa- 
sional determinations  of  either  the  chemical  or  bacterial  properties  of 
water  are  of  little  value.  A  single  water  analysis  is  often  misleading, 
especially  in  surface  waters,  which  may  vary  greatly  from  time  to  time. 
A  river  water  may  require  repeated  examinations  extending  over  long 
periods  of  time  correlated  with  conditions  of  rainfall,  stream  flow, 
wind,  temperature,  sewage  pollution,  and  other  factors  in  order  to  be 
helpful. 

There  have  been  much  conflict  and  useless  discussion  between  chem- 
ists and  bacteriologists  concerning  the  relative  advantages  of  their 
methods.  The  chemists  were  first  in  the  field,  but  the  limitations  of 
chemical  methods  were  strongly  emphasized  when  it  was  shown  that 
chemistry  can  only  indicate  pollution  but  cannot  discover  infection. 
Much  was  hoped  from  bacteriology,  but  it  is  rather  exceptional  that 
bacteriologists  are  able  to  isolate  pathogenic  microorganisms  from  a 
sample  of  water.  For  the  most  part,  the  routine  bacteriological  exam- 
ination of  water  does  nothing  more  than  the  chemical  examination,  that 
is,  it  shows  pollution  but  does  not  prove  infection.  Both  chemical 
and  bacterial  analyses  of  water  have,  therefore,  distinct  limitations; 
they  do  not  antagonize,  but  supplement  each  other.  From  the  chemical 
side  we  learn  much  of  the  past  history  of  a  water ;  the  bacteriology  tells 
us  more  of  its  present  state.  Chemical  methods  reign  supreme  when  we 
desire  to  discover  the  presence  of  lead  or  other  inorganic  poisons;  also 
in  determining  the  hardness,  mineral  and  organic  constituents,  etc. 
From  the  number  and  character  of  the  bacteria  in  water  we  obtain  a 
fair  index  of  the  presence  and  degree  of  pollution.  Occasionally  bac- 
teriologists may  determine  whether  a  water  contains  certain  specific 
agents,  such  as  cholera  vibrio.  It  must,  however,  be  admitted  that  the 
ordinary  routine  chemical  and  bacterial  examination  of  water  affords 
but  meager  information,  especially  when  only  one  analysis  has  been 
made.  Fortunately,  the  inferences  drawn  from  a  sanitary  water  analysis 
are  on  the  safe  side,  as  many  good  waters  are  condemned,  so  that  it 
would  be  very  difficult  for  an  unsafe  water  to  pass  the  muster  of  a 
complete  sanitary  analysis.     At  most,  the  information  furnished  is  only 

866 


INTEEPEETATIOK  OF  SANITAEY  WATEE  ANALYSTS     867 

of  i^resent  conditions  and  is  not  a  guarantee  of  future  safety.  A  surface 
water  or  a  ground  water  may  to-day  be  exceptionally  free  from  chemical 
impurities  and  practically  sterile  bacteriologically,  whereas  to-morrow  it 
may  contain  typhoid,  dysentery,  cholera,  or  other  water-borne  infections ; 
these  may  come  from  sources  that  would  at  once  be  perfectly  evident 
from  a  sanitary  survey  of  the  watershed. 

A  sanitary  survey  of  the  catchment  area  is  frequently  of  much 
greater  practical  importance  than  all  the  information  furnished  by  the 
laboratory.  It  needs  neither  chemists  nor  bacteriologists  to  tell  us  that 
the  water  from  a  creek  with  an  overhanging  privy  a  short  distance  above 
will  some  day  carry  infection;  or  that  the  water  from  a  shallow  well 
in  limestone  or  coarse  gravel  very  near  a  leaking  cesspool  must  be  a 
source  of  danger.  A  sanitary  survey  is  able  to  discover  the  sources  of 
contamination,  the  kinds  of  pollution,  and  the  degree,  often  with  greater 
precision  than  combined  chemical  or  bacteriological  tests.  No  sanitary 
analysis  of  a  water  can  therefore  be  considered  complete  unless  it  includes 
an  examination  of  the  watershed  and  a  study  of  the  geology  and  to- 
pography of  the  catchment  area. 

From  a  sanitary  standpoint,  the  principal  substances  to  look  for  in 
a  chemical  analysis  are  the  organic  matter,  nitrates,  nitrites,  and  chlorin. 
Of  these  the  nitrites  are  the  greater  danger  signal,  indicating  oxidation 
of  organic  matter  through  bacterial  activity.  High  chlorin  and  nitrates 
without  nitrites  indicate  passed  or  remote  pollution;  this  is  a  frequent 
combination  in  ground  waters.  The  ammonias  (free  and  albuminoid) 
are  a  measure  of  the  amount  of  nitrogenous  organic  matter  in  the  water. 
A  surface  water  may  safely  contain  an  amount  of  albuminoid  ammonia 
that  would  be  suspicious  in  a  ground  water.  The  significance  of  the 
chlorin  varies  with  the  location  and  source  of  the  water.  Ground  waters 
should  contain  fewer  bacteria  than  surface  waters.  Artesian  wells  should 
be  practically  sterile,  and  a  good  surface  water  should  not  contain  over 
100  bacteria  per  cubic  centimeter.  Waters  that  vary  in  composition 
from  time  to  time  without  evident  cause  must  be  regarded  as  unsafe. 
This  applies  particularly  to  ground  waters.  Surface  waters  vary  greatly 
as  the  result  of  freshets,  etc.,  but  a  ground  water,  pond,  or  lake  should 
show  no  such  sudden  variations. 

These  general  statements  may  be  quite  misleading  when  interpreting 
the  analysis  of  a  specific  case.  Therefore  several  selected  analyses  and 
interpretations  have  been  given  below. 

Allowable  Limits. — The  following  are  sometimes  considered  as  the 
allowable  limits  of  the  impurities  commonly  regarded  as  permissible  in 
drinking  water. 

Chlorin  depends  upon  the  normal  chlorin  content  of  unpolluted  sur- 
face waters  in  the  neighborhood. 

Bacteria  not  over  100  per  cubic  centimeter. 


868     USTTERPRETATION  OF  SANITARY  WATER  ANALYSIS 


Colon  bacillus  should  be  absent  from  the  ground  water, 
than  1  per  10  c.  c.  in  a  stream  or  in  a  river  water. 


Not  more 


Free  ammonia 0.015-0.03 

Albuminoid  ammonia 0 .  07  -0 .  35 

Nitrogen  as  nitrites None,  or  at  most  a  trace  (0 .  0004) 

Nitrogen  as  nitrates 0 . 3  to  1 . 6 

[Parts  per  million] 

The  standard  adopted  by  the  government^  for  drinking  water  sup- 
plied by  common  carriers  in  interstate  commerce  demands  that  the  total 
number  of  bacteria  shall  not  exceed  100  per  cubic  centimeter  when 
grown  on  standard  agar  plates  and  counted  after  twenty-four  hours'  in- 


Much  Organic  Matter 
"      CI 
"     NO  3     &    NO3 


Few  or  No  Bacteria 


,.'  '■'■'  -Wafer /L-e(>e/V 


Organic  Matter 
small  amt.  CI 
NO  3 
no  NO, 


Few  or  No  Bacterid 


Fig.  107. — Diagram  Illustrating  the  Character  of  the  Ground  Water  in  Rela- 
tion TO  Soil  Pollution,  to  Assist  the  Interpretation  of  a  Sanitary  Analysis. 
(See  also  Nitrogen  Cycle,  page  773.) 

cubation  at  37°  C.  Further,  that  not  more  than  one  out  of  five  10  c.  c. 
portions  of  any  sample  examined  shall  show  the  presence  of  organisms 
of  the  bacillus  coli  group. 

These  figures  must  not  be  taken  literally,  and  are  not  given  as 
standards  of  purity,  but  the  maximumx  limits  of  the  impurities  allowable 
under  ordinary  conditions.  It  will  be  seen  from  the  illustrative  analyses 
given  below  that  at  times  these  limits  may  be  exceeded  without  sanitary 
significance,  whereas  at  other  times  a  water  well  within  the  prescribed 
limits  may  contain  infection. 

For  a  better  understanding  a  number  of  sanitary  analyses  of  water 
are  given  with  an  interpretation.  The  student  is  advised  first  to  study 
the  analyses,  draw  his  own  conclusions,  and  then  compare  them  with  the 
interpretation  given. 


^Public  Pealth  Reports,  Nov.  16,  1914.     No.  29,  Vol.  45,  p.  2959. 


INTEEPEETATION  OF  SAMTAEY  WATER  ANALYSIS     869 

Analysis  No.  1 — Gross  Pollution 

Free  ammonia 0 .  214  part  per  million 

Albuminoid  ammonia 0.810      "  "  " 

Nitrogen  as  nitrites 0.005     "  "  " 

Nitrogen  as  nitrates 21 .0  parts  "  " 

Chlorin 47.0  "  " 

Total  residue 412 . 0  "  " 

Volatile  residue 279.0  "  "  " 

Fixed  residue 133.0 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 65,000 

Bacteria  per  c.  c.  upon  agar  at  37°  C ; 120,000 

Many  liquefying  colonies.  Many  chromogens  per  c.  c.  Fer- 
mentation in  lactose  bouiUon  in  0.001  c.  c.  B.  coli  present  in 
0.01  c.  c. 

This  represents  a  grossly  polluted  water  and  should  unhesitatingly 
be  condemned,  no  matter  what  its  source. 

The  following  analysis  of  the  Hamburg  public  supply  from  the 
Elbe  Eiver  during  the  cholera  epidemic  of  1892  is  given  in  Chemical 
News,  LXVI,  144 : 

Analysis  No.  2 — Elbe  River  During  Cholera  Epidemic 

Appearance Turbid  and  very  yellow 

Taste Slightly  unpleasant 

Odor Extremely  little 

Deposit Small  and  dirty-looking 

Chlorin 472 . 0    parts  per  million 

Free  ammonia 1 .  065    "       " 

Albuminoid  ammonia 0 .  293    "        " 

Nitrates 26.43      "        " 

Required  oxygen  (15  minutes) 0.928    "        " 

Required  oxygen  (4  hours) 3 .  428    "        " 

Total  soUds 1,160.7        "       « 

This  is  given  simply  as  an  instance  of  a  grossly  polluted  river 
(Elbe)  water,  known  to  be  infected. 

Analysis  No.  3 — Boston  Tap,  Typical  (not  averaged  results) 

Free  ammonia 0 .  010  part   per  million 

Albuminoid  ammonia 0. 114    "         "  " 

Nitrogen  as  nitrites 0.000    "         "  « 

Nitrogen  as  nitrates 0.02      "         "  " 

Chlorin 2.7      parts    "  « 

Total  residue 27.0        "        "  " 

Volatile  residue 10.0        "        "  " 

Fixed  residue 17.0        «        «  « 

Hardness,  13°. 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 77 

B.  coli None 


870     INTEEPRETATION  OF  SANITAEY  WATER  ANALYSIS 

This  is  a  surface  water,  collected  in  impounding  reservoirs  and 
stored  about  30  days  before  it  reaches  the  consumer.  The  watershed 
is  fairly  well  protected.  The  chemical  analysis  shows  little  organic 
pollution;  the  ammonias  are  moderate  in  amount,  nitrites  absent; 
nitrates  low;  chlorin  normal;  bacteria  indicating  nothing  suspicious. 
The  water  is  of  good  sanitary  quality,  judged  by  chemical  and  bacterial 
analysis. 

Analysis  No.  4 — A  Suspicious  Water 

Free  ammonia 0 .  018  part   per  million 

Albuminoid  ammonia 0 .  020    "  "  " 

Nitrogen  as  nitrites 0 .  007    "  "  « 

Nitrogen  as  nitrates 1.5      parts    "  " 

Chlorin 19 .3        «  "  « 

Total  residue 106.0        "  "  « 

Volatile  residue 37.0        "  «  " 

Fixed  residue 69.0        "         "         « 

Hardness,  33.8°. 

(The  residue  did  not  char  and  gave  no  odor  upon  ignition.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 60 

Bacteria  per  c.  c.  upon  agar  at  37°  C 45 

No  liquefying  colonies.     One  chromogen  per  c.  c.     No  fermen- 
tation in  lactose  bouillon  in  10  c.  c.     No  B.  coli. 

This  water  came  from  a  driven  well  at  Wenham,  Mass.  Upon  in- 
spection it  was  found  that  the  well  was  400  feet  from  a  stable,  200 
feet  from  a  cesspool,  and  250  feet  from  the  house. 

The  first  thing  that  strikes  our  attention  in  this  analysis  is  the  high 
chlorin.  This,  however,  lacks  sanitary  significance,  as  it  is  normal  for 
the  ground  waters  of  this  neighborhood.  The  hardness  of  the  water  is 
due  to  the  very  fertile  character  of  the  surrounding  soil  through  which 
the  water  percolates.  The  carbonic  acid  taken  up  by  the  water  from 
the  decomposing  organic  matter  dissolves  the  lime  in  the  soil.  The 
organic  matter  as  represented  by  the  ammonias  is  quite  low.  The 
nitrates  are  high  and  indicate  that  the  water  has  dissolved  this  end 
product  of  the  oxidation  of  organic  matter  in  its  passage  through  the 
soil  and  perhaps  in  seepage  from  the  cesspool.  The  noticeable  quantity 
of  nitrites  indicates  that  all  the  organic  matter  has  not  beeli  consumed 
and  that  the  mineralization  is  not  complete.  The  small  number  of 
bacteria  present  shows  that  the  filtering  action  of  this  oil  through  which 
the  water  passes  is  effective  in  keeping  out  sewage  contamination  either 
from  the  surface  or  from  the  cesspool.  This  conclusion  is  strength- 
ened by  the  absence  of  fermenting  organisms  and  especially  the  absence 


IN^TEEPEETATION  OF  SANITAKY  WATEK  ANALYSIS     871 

of  B.  coll.  The  absence  of  liquefying  bacteria  and  the  presence  of  an 
occasional  chromogenic  organism  indicate  that  there  is  little  or  no  con- 
tamination from  the  surface  and,  in  fact,  upon  inspection  the  platform 
covering  the  well  was  found  to  be  tight  and  well  constructed. 

This  particular  sample  of  well  water  shows  nothing  injurious  to 
health,  and  if  subsequent  analyses  are  equally  satisfactory  the  water 
may  be  used  without  fear  for  drinking  purposes.  It  is  plain,  however, 
that  this  well  needs  watching,  for  it  is  evident  that  the  soil  is  already 
surcharged  with  organic  matter,  some  of  which  appears  in  the  water, 
and  a  further  loading  of  the  soil  or  a  break  in  the  cesspool  might 
readily  infect  the  well. 

Analysis  No.  5 — Surface  Pollution  of  a  Well 

Free  ammonia 0 .  022  part  per  million 

Albuminoid  ammonia 0 .  035    "  "         " 

Nitrogen  as  nitrites 0 .  007    "  "         " 

Nitrogen  as  nitrates 1.0        "  "         " 

Chlorin 19.0      parts  " 

Total  residue 356.0 

Volatile  residue 151.0 

Fixed  residue 205.0        "  «         « 

(Residue  charred  upon  ignition  with  disagreeable  odor.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 9 

Bacteria  per  c.  c.  upon  agar  at  37°  C 275 

Many  liquefying  colonies.  Several  chromogens  per  c.  c.  Fer- 
mentation in  lactose  bouiUon  in  0.1  c.  c.  B.  coli  present  in 
1  c.  c. 

This  is  a  shallow  well  in  Washington,  D.  C,  28  feet  deep,  the  water 
standing  4  feet  in  the  well.  There  is  a  sewer  60  feet  from  the  well 
and  a  privy  within  a  block.  The  pump  is  old  and  of  wood  and  the 
cover  to  the  well  is  rotten  at  the  base. 

Although  this  water  contains  a  small  amount  of  organic  matter, 
as  indicated  by  the  ammonias,  every  other  factor  indicates  pollution 
both  present  and  past.  The  nitrates  and  nitrites  are  high;  the  chlorin 
is  excessive.  It  is  important  to  notice  that  this  water  has  only  9  bac- 
teria per  cubic  centimeter  when  judged  by  the  colonies  that  grow  upon 
gelatin  at  20°  C.  Nevertheless,  it  contains  colon  bacilli  in  1  c.  c,  other 
fermenting  organisms,  as  well  as  liquefying  and  chromogenic  colonies. 
It  is  probable  that  most  of  the  contamination  in  this  case  came  from 
the  surface,  as  the  well  had  a  very  poor  and  leaky  platform.  This 
water  should  not  be  used  for  domestic  purposes,  and  if  it  did  not  ma- 
terially improve  after  the  correction  of  the  platform  it  should  be  con- 
demned. 


872     INTEEPRETATTON  OF  SANITAEY  WATER  ANALYSIS 

Analysis  No.  6 — Well  Water,  Surface  Pollution 

Free  ammonia 0.007  part  per  million 

Albuminoid  ammonia 0.018      "  "  " 

Nitrogen  as  nitrites 0.0005    "  "  " 

Nitrogen  as  nitrates 2.5  parts  "  " 

Chlorin 14.0          «  «  « 

Total  residue 62.0          «  "  « 

Volatile  residue 32.0          «  «  « 

Fixed  residue 30.00        «  «  « 

(Residue  charred  upon  ignition  and  gave  disagreeable  odor.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 820 

Bacteria  per  c.  c.  upon  agar  at  37°  C 640 

Many  liquefying  colonies.     Many  chromogens  per  c.  c.    Fer- 
mentation in  lactose  bouillon  in  1  c.  c.    B.  coli  in  10  c.  c. 

This  water  came  from  a  shallow  well  in  Washington,  D.  C,  18  feet 
deep,  the  water  standing  3  feet  from  the  bottom.  The  rather  high 
nitrates  and  chlorin  in  this  case  represent  past  pollution.  The  small 
amount  of  organic  matter  with  a  trace  of  nitrites  plus  the  number  and 
character  of  the  bacteria  indicate  surface  pollution.  This  view  is 
strengthened  by  the  fact  that  repeated  examinations  of  the  water  from 
this  well  showed, marked  variations  in  the  number  of  bacteria.  Upon 
inspection  the  pump  and  covering  to  the  well  were  found  in  very  bad 
condition,  leaky,  and  with  surface  drainage  toward  the  well. 

Analysis  No.  7 — Illustrating  Remote  Pollution 

Free  ammonia 0.006  part  per  million 

Albuminoid  ammonia 0.011    "  "  " 

Nitrogen  as  nitrites trace     "  "  " 

Nitrogen  as  nitrates 20.0     parts  "  " 

Chlorin 89.0        «  "  « 

Total  residue 430.0        «  «  " 

Volatile  residue 113.0        «  «  « 

Fixed  residue 317.0        «  «  " 

(No  charring  upon  ignition;  odor  of  burning  rubber.) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 92 

Bacteria  per  c.  c.  upon  agar  at  37°  C 16 

No  liquefjdng  colonies.    No  chromogens  per  c.  c.    No  fermen- 
tation in  lactose  bouillon  in  10  c.  c.    B.  coli  absent. 

This  is  a  ground  water  from  a  shallow  well  in  Washington,  D.  C. 
The  well  is  29  feet  deep  and  the  water  stands  4  feet  from  the  bottom. 
Top  is  well  protected,  waste  water  drains  to  sewer  nearby.  There  are 
two  privy  vaults  within  two  blocks  of  the  well. 


INTERPRETATION  OF  SANITARY  WATER  ANALYSIS     873 

The  analysis  shows  high  chlorin  and  nitrates;  otherwise  nothing 
suspicious.  This  means  remote  pollution.  The  organic  matter  has  beei 
completely  mineralized  and  the  bacteria  held  back  by  the  soil. 

Analysis  No.  8 — High  Chlorin 

Free  ammonia 0.016  part  per  million 

Albuminoid  ammonia 0.015    "  "  " 

Nitrogen  as  nitrites 0.000    "  «  « 

Nitrogen  as  nitrates 0. 14      "  «  « 

Chlorin 11.20    parts  «  « 

Total  residue "  "  « 

Volatile  residue "  "  " 

Fixed  residue "  "  " 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 48 

Bacteria  per  c.  c.  upon  agar  at  37°  C 12 

No  liquefying  colonies.    No  chromogens  per  c.  c.    No  fermen- 
tation in  lactose  bouillon  in  10  c.  c.     B.  coli  absent. 

This  water  is  from  a  driven  well  at  Beverley,  Mass.  The  analysis 
shows  nothing  suspicious,  excepting  the  high  chlorin,  which  is  normal 
for  this  neighborhood  and  therefore  lacks  sanitary  significance. 

Analysis  No.  9 — High  Free  Ammonia;  Deep  Well 

Free  ammonia 0. 170  part  per  million 

Albuminoid  ammonia 0.000    « 

Nitrogen  as  nitrites trace      "  "  " 

Nitrogen  as  nitrates 0.0        "  "  " 

Chlorin 3.1      parts  «  « 

Total  residue 115.0        "  «  « 

Volatile  residue 45.0        "  «  * 

Fixed  residue 70.0        «  «  « 

No  bacteria  per  c.  c.  upon  gelatin  at  20°  C. 
No  bacteria  per  c.  c.  upon  agar  at  37°  C. 
No  fermentation  in  lactose  bouillon. 

This  water  is  from  a  driven  well  in  Washington,  D.  C;  96  feet 
deep,  water  stands  81  feet  from  the  bottom.  Good  platform  and  drain, 
and  pump  is  in  first-class  condition. 

It  is  exceptionally  pure,  both  chemically  and  bacteriologically,  ex- 
cepting the  large  amount  of  free  ammonia.  This  supposedly  comes 
from  the  reduction  of  nitrates. 

It  is  not  uncommon  to  find  water  from  deep  wells  to  be  high  in  free 
ammonia,  and  it  is  assumed  that  this  comes  from  a  chemical  reduction 
under  high  pressure,  and  perhaps  temperature  of  the  nitrogenous  matter 
in  coal  and  alluvial  deposits. 


874     mTERPRETATTON  OF  SAXTTABY  WATER  ANALYSTS 

Analysis  No.  10 — Rain  Water  Stored  and  Polluted 

Free  ammonia 1 .  050  parts  per  million 

Albuminoid  ammonia 0 .  175 

Chlorin 2.0 

Nitrogen  as  nitrites strong  trace 

Nitrogen  as  nitrates 0.0 

Required  oxygen 2 .  25 

Total  residue 20.0 

Bacteria  per  c.  c.  upon  gelatin  at  20" .  . . , 625 

No  fermenting  organisms.    No  B.  coli. 

This  is  rain  water  from  a  dirty  cistern.  In  appearance  the  water 
was  clear  and  good.  The  analysis  shows  that"  the  water  is  dirty  and 
contaminated  with  organic  matter.  The  bacteriological  results  indicate 
absence  of  fecal  pollution.  The  water  is  undesirable,  but  not  dangerous, 
as  far  as  infection  is  concerned. 


Analysis  No.  U — Artesian  Well  Water,  Showing  the  Effects  of  Storage 
(The  figures  are  in  parts  per  million) 


Free  ammonia 

Albuminoid  ammonia 

Nitrogen  as  nitrites 

Nitrogen  as  nitrates 

Chlorin 

Dissolved  oxygen 

Oxygen  required 

Total  residue 

Volatile  residue 

Fixed  residue  (mineral  matter) 

Bacteria  per  c.  c.  upon  gelatin  at  20°  C 

Fermentation  in  lactose  bouillon 

B.  coli 


Water  Directly 

fsame  water 

from  the 

Storage  Cistern 

from  the  Well 

.052 

.062 

.003 

.016 

.000 

.0007 

.01 

.01 

10.4 

10.2 

10.65 

10.69 

.10 

.15 

111.0 

97. 

40.0 

30. 

71.0 

67. 

6. 

6500. 

in  none 

in  0.1  c.  c. 

absent 

absent 

This  water  is  from  eight  artesian  wells  at  the  Government  Hospital 
for  the  Insane  at  Anacostia,  D.  C,  375  feet  deep.  The  water  is  forced 
out  by  compressed  air  and  flows  by  gravity  to  the  storage  cistern,  which 
is  of  brick  and  cement,  and  has  a  capacity  of  80,000  gallons. 

It  will  be  observed  that  this  water  is  low  in  total  solids  and  is 
almost  free  of  organic  matter  as  represented  by  the  ammonias,  nitrites, 
nitrates,  and  oxygen  required.  The  water  is  clear  as  it  flows  from  the 
ground,  but  soon  turns  slightly  yellowish  on  account  of  a  small  amount 
of  iron  in  the  ferrous  state  that  is  oxidized  to  the  ferric  salt,  which 
is  insoluble  and  is  precipitated  upon  contact  with  the  air.  The  amount 
of  chlorin  is  somewhat  large,  but  has  no  sanitary  significance  in  this 


INTEEPEETATION  OF  SANITAEY  WATEK  ANALYSIS     875 

case.  The  principal  point  in  this  analysis  is  the  bacteriology,  which 
shows  the  water  to  be  practically  sterile  as  it  flows  from  the  ground, 
but  which  contains  over  6,000  bacteria  per  cubic  centimeter  in  the  storage 
cistern.  These  come  from  the  air  and  other  contaminating  objects,  and 
illustrate  the  great  growth  of  the  common  water  bacteria  in  water 
stored  under  these  circumstances.  The  slight  increase  of  the  ammonias 
and  nitrites  in  the  cistern  water,  as  compared  with  the  water  direct 
from  the  well,  indicates  organic  pollution  and  bacterial  activity.  The 
diminution  in  the  residue  results  largely  from  separation  of  the  iron. 

Analysis  No.  12 — Chemical  and  Bacteriological  Changes  in  Potomac  River  Water 
as  the  Result  of  Storage  and  Filtration 

(The  figures  are  the  averages  of  fourteen  representative  analyses) 


Dalecarlia 

Inlet 

Raw  Water 

Entering 

Storage 

Reservoir 

Dalecarlia 

Outlet 

Raw  Water 

After 

About 

3  Days' 

Storage 

Georgetown 

Reservoir 

Second 

Storage 

Reservoir 

(Water 

Remains, 

Here  About 

a  Day) 

Washington 
Reservoir 

3rd  Storage 
Basin 
Water 

Applied  to 
Filter 

Filtered 
Water 
from 
Filtered 
Water 
Reservoir 

0.024 

0.161 

0.0031 

0.61 

2.6 

203.0 
47.1 

156.0 

526 
42 
28 
71 

0.027 

0.131 

0.0051 

0.57 

2.61 

163.0 
48.0 

115.0 

381 
40 
40 
80 

0.022 

0.117 

0.0065 

0.6 

2.61 

160.0 
49.0 

111.0 

306 
33 
40 
73 

0.017 

0.096 

0.0056 

0.61 

2.47 

141.0 
41.0 

100.0 

235 
16 
41 
52 

0.015 

Albuminoid  ammonia 

0.054 
0.0003 

0.67 

2.53 

127.0 

39.0 

88.0 

Bacteria  per  c.  c.  upon  gelatin 
at  20°  C  

36 

Per  cent,  of  B.  coli  in  1  c.  c. . . 
Per  cent,  of  B.  coli  in  10  c.  c. . 
Total  per  cent,  showing  B.  coli 

4.7 
9.5 
14.2 

This  water  is  pure  and  wholesome,  despite  the  fact  it  contains  many 
more  bacteria  than  that  usually  allowed.  It  has  been  used  for  some 
years  by  about  3,000  persons,  who  are  singularly  free  from  typhoid  fever 
and  other  water-borne  diseases. 

Analysis  No.  12  is  a  good  illustration  of  the  bacteriological  and 
chemical  character  of  a  river  water,  and  illustrates  the  changes  that 
occur  during  short  storage  (3  to  5  days)  and  after  filtration  through  a 
slow  sand  filter. 

It  will  be  seen  from  this  table  that  there  is  a  gradual  diminution 
in  the  amount  of  free  ammonia  and  a  more  marked  diminution  in  the 
amount  of  albuminoid  ammonia.  The  amount  of  organic  matter  as 
represented  by  the  ammonias  is  diminished  Just  one-third.  The  nitrites 
show  an  increase  during  storage  of  the  water,  indicating  active  oxida- 
tion, but  a  marked  decrease  after  it  is  filtered,  showing  the  rapid  com- 
pletion of  the  oxidation  of  the  organic  matter  in  the  filter.  The  nitrates 
show  a  tendency  to  increase  in  amount,  which  would  be  expected  as 


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INTEEPEETATION  OF  SANITAEY  WATER  ANALYSIS     877 

the  nitrites  diminish.  It  is  evident  that  storage  and  filtration  have  little 
effect  upon  the  chlorin  content  of  the  water.  The  total  residue  diminishes 
as  the  result  of  storage,  sedimentation,  and  filtration.  It  will  be 
noted,  however,  that  this  diminution  is  more  marked  with  the  fixed 
residue  than  with  the  volatile  residue. 

The  number  of  bacteria  decreases  as  the  result  of  storage,  but  the 
most  marked  decrease  occurs  as  the  result  of  filtration.  It  should  be 
remembered  that  all  the  bacteria  in  the  filtered  water  do  not  represent 
those  which  have  passed  the  filter.  The  effect  of  the  few  days'  storage 
upon  this  water  does  not  very  materially  affect  the  number  of  B.  coli, 
but  there  is  a  marked  diminution  in  their  number  as  the  result  of 
filtration. 

The  analyses  of  surface  waters,  shown  in  the  table  on  page  876,  with 
diagram  showing  the  locations  from  which  samples  were  obtained,  will 


.   ^  .     VPLAHD     *olS:-:*j?i;v^^- SWAMP  ;,        /UPLAND 


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Fig.  108. — Diagram  Showing  Location  of  Samples. 

repay  careful  study.     This  table  and  diagram  were  furnished  through 
the  kindness  of  Professor  Whipple. 

The  diagram  above   (Eig.  108)   shows  the  location  of  the  samples 
employed  in  Analysis  No,  13. 


CHAPTEE   V 
THE   PURIFICATION   OF   WATEE 

The  ways  in  which  water  may  be  purified  for  practical  purposes  are 
not  many.  It  is  worth  noting  that  most  of  the  advances  in  water  puri- 
fication come  from  the  development  of  old  empiric  processes.  It  is  only 
at  long  intervals  that  a  new  method  or  principle  of  treatment  is  dis- 
covered that  is  important  enough  to  find  a  permanent  place  in  the  art  of 
water  purification. 

The  principal  methods  at  present  serviceable  for  the  purification  of 
water  upon  a  large  scale  are:  (1)  storage,  (2)  filtration,  (3)  chemicals, 
such  as  ozone,  hypochlorite  of  lime,  sulphate  of  aluminium  or  iron,  (4) 
ultra  violet  rays. 

No  method  of  purifying  water  can  be  considered  to  approach  a 
satisfactory  hygienic  standard  that  does  not  first  of  all  practically  elim- 
inate water-borne  diseases.  The  process  must  also  reduce  the  turbidity 
and  color  to  inappreciable  amounts  and  remove  something  like  99  per 
cent,  of  the  bacteria,  when  these  organisms  result  from  sewage  pollution 
and  are  fairly  numerous:  there  is  perhaps  no  -final  reason  for  the  bac- 
terial standard.  It  has  been  adopted  by  consent  because  it  represents 
a  purification  that  is  reasonably  satisfactory  and  that  can  be  accom- 
plished at  the  small  cost  of  about  $10.00  per  million  gallons  of  water 
treated.  With  the  further  awakening  of  the  sanitary  conscience  of  the 
community  the  standards  will  inevitably  tend  higher,  and  it  is  probable 
that  in  time  our  standards  will  approach  an  ideal  that  is  now  not  re- 
garded as  necessary.  At  present  there  is  no  evidence  that  the  few  micro- 
organisms left  in  the  water  after  a  satisfactory  method  of  purification, 
such  as  slow  sand  filtration,  are  injurious.  Certainly,  if  injurious  in- 
fluence is  exercised,  it  is  too  small  to  be  determined  or  measured  by 
any  methods  now  at  our  disposal. 


NATURE'S  METHODS  OF  PURIFYING  WATER 

In  nature,  water  is  purified  by  various  methods,  the  chief  of  which 
are:  (a)  evaporation  and  condensation,  which  makes  rain  water  the 
purest  of  natural  waters;  (b)  the  self -purification  of  running  streams, 
which  is  a  variable  and  uncertain  quantity;  (c)  storage  in  lakes  and 
ponds  which  clarifies  water  and  in  time  eliminates  danger;  and    (d) 

878 


NATUEE'S  METHODS  OF  PUEIFYING  WATEE     879 

the  physical,  chemical,  and  biologic  action  of  the  soil  upon  water  that 
filters  through  the  soil  into  the  earth,  which  is  one  of  nature's  greatest 
purifying  agencies. 

Evaporation  and  Condensation. — The  purifying  action  of  the  dis- 
tilling and  condensing  process  through  which  all  meteoric  water  passes 
is  one  of  nature's  beneficent  processes.  Enormous  quantities  of  sea 
water,  marsh  water,  and  polluted  waters  of  all  kinds  are  thus  returned 
to  us  suitable  for  domestic  use.  Somerville  estimates  that  "186,240 
cubic  miles  of  water  are  annually  raised  from  the  surface  of  the  globe 
in  the  form  of  vapor,  chiefly  in  the  intertropical  seas."  Water  is  thus 
constantly  being  purified  in  nature.  The  ocean  has  been  compared  to  a 
boiler,  the  sim  to  a  furnace,  and  the  atmosphere  to  a  vast  still.  The 
cooler  air  of  the  higher  atmosphere  and  of  colder  zones  acts  as  a  con- 
denser, causing  the  precipitation  of  the  distilled  water  as  rain.  About 
three-fourths  of  the  earth's  surface  (145,000,000  square  miles)  is  cov- 
ered with  water,  much  of  which  is  in  the  tropical  belt. 

Self-purification  of  Streams. — The  self-purification  of  streams  needs 
special  discussion.  Streams  become  purer,  during  the  course  of  their 
flow.  Of  this  there  can  be  no  doubt.  This  half-truth  based  upon  chemi- 
cal data  has  in  the  past  suffered  sanitarians  to  permit  the  use  of  water 
that  now  we  know  was  responsible  for  much  sickness  and  many  deaths. 
Streams  become  purer,  but  not  pure.  Some  impurities  always  remain, 
that  is,  the  process  is  not  complete  and  final.  All  surface  supplies  are 
now  regarded  with  suspicion  and  are  either  stored,  filtered,  or  other- 
wise purified  before  they  are  used  by  educated  communities. 

It  was  formerly  said  that  a  stream  purifies  itself  in  seven  miles. 
Such  a  generalization  is  absurd.  We  now  know  that  it  is  not  the  dis- 
tance so  much  as  the  time  and  opportunity  for  the  various  factors  in- 
volved to  become  effective.  Thus,  Buffalo's  sewage  flows  to  Niagara's 
intake,  a  distance  of  about  16  miles,  in  a  few.  hours.  There  is  little 
chance  for  self -purification  to  take  place,  and  despite  the  great  dilution 
the  danger  is  very  great.  Niagara's  average  typhoid  rate  for  10  years, 
from  1899  to  1908,  was  132.9  per  100,000,  the  highest  in  the  country. 
A  brisk  flow  brings  the  microorganisms  of  disease  alive  and  virulent  to 
the  intake  of  the  water  works  below;  sluggish  flow  or  stagnation  corre- 
sponds to  storage  and  results  in  the  destruction  of  most  of  the  bacteria 
which  cause  water-borne  infections. 

A  good  instance  of  the  self-purification  of  streams  was  found  in 
the  studies  of  the  Potomac  Eiver  and  its  relation  to  typhoid  fever  in 
the  District  of  Columbia.  The  Potomac  Eiver  drains  an  area  of  about 
11,400  square  miles  which,  in  1900,  contained  a  population  estimated 
to  be  about  half  a  million,  or  about  44  per  square  mile.  The  velocity  of 
the  flow  of  the  Potomac  is  extremely  variable.  It  takes  from  4  to  7 
days  for  the  water  to  travel  from  Cumberland  to  Great  Palls   (where 


880  THE  PURIFICATION  OF  WATER 

the  Washington  intake  is  located),  a  distance  of  about  176  miles.  The 
waters  of  the  Potomac  are  directly  polluted  by  sewage  at  numerous 
points.  The  direct  pollution  is  contributed  by  about  45,000  individuals, 
or  9.1  per  cent,  of  the  total  population  on  the  watershed.  Of  this 
pollution  about  80  per  cent,  enters  the  river  at  points  176  or  more 
miles  from  the  intake  at  Great  Falls,  about  15  per  cent,  enters  it  at 
points  between  50  and  170  miles  above  Great  Falls,  and  5  per  cent, 
is  contributed  by  about  2,200  of  the  population  and  enters  the  river  at 
points  between  19  and  50  miles  above  the  intake.  There  is  practically 
no  direct  pollution  of  the  Potomac  within  19  miles  of  the  intake.  Here 
we  have  an  instance  of  a  stream  draining  an  extensive  and  populous 
area  and  receiving  industrial  and  human  wastes  from  many  thousand 
persons.  Nevertheless,  self-purification  has  occurred  to  such  an  extent 
that  little,  if  any,  of  the  typhoid  fever  occurring  in  Washington  could 
be  attributed  to  the  use  of  this  water. 

The  Mississippi  River  is  perhaps  one  of  the  best  examples  of  the 
self-purification  of  a  stream,  for,  after  draining  almost  the  entire  conti- 
nental United  States  in  a  flow  of  over  3,000  miles,  it  is  exceptionally 
free  of  intestinal  bacteria  at  New  Orleans,  judged  by  the  comparative 
absence  of  colon  bacilli. 

The  principal  factors  concerned  in  the  self-purification  of  water  are 
varied  and  interesting.  They  are:  (1)  Chemical,  the  oxidation  of 
nitrogenous  organic  matter,  resulting  in  its  reduction  or  mineraliza- 
tion. (2)  Biologic,  the  death  of  microorganisms  through  symbiosis, 
time,  and  various  means;  and  (3)  physical,  such  as  dilution,  sedimenta- 
tion, sunlight,  etc. 

•  Oxidation. — Organic  matter  is  gradually  oxidized,  thus  diminishing 
the  amount  of  food  for  bacteria.  The  activity  of  the  oxidation  depends 
largely  upon  the  amount  of  dissolved  oxygen  in  the  water.  It  is  there- 
fore favored  by  falls,  rapids,  and  a  turbulent  flow.  It  is  mainly  the 
aerobic  bacteria  which  have  an  active  proteolytic  action,  and  are  thus 
able  to  digest  and  destroy  organic  matter.  During  the  course  of  flow 
the  complex  nitrogenous  substances  are  thus  mineralized.  Chemical 
analyses  show  a  rapid  decrease  in  the  amount  of  organic  matter  and  a.ii 
increase  of  nitrates,  and  diminution  of  nitrites.  It  was  these  facts 
that  led  chemists  to  conclude  that  flowing  rivers  soon  purified  them- 
selves. 

Biological  Factors. — Minute  animals  such  as  infusoria,  amebae, 
water-worms,  water-fleas,  etc.,  which  exist  in  countless  numbers  in 
certain  waters,  feed  upon  the  organic  matter  and  bacteria,  and  are  a 
considerable  factor  in  the  self -purification  of  water. 

Time  and  symbiosis  play  an  important  role  with  self-purification 
of  streams,  as  they  do  elsewhere.  Pathogenic  bacteria  die  more  quickly 
in  a  polluted  water  than  in  a  pure  water.    It  is  probable  that  symbiosis 


NATURE'S  METHODS  OF  PUEIFYING  WATER         881 

and  antibiosis  here  plays  a  part.  The  saprophytic  bacteria  somehow  help 
to  kill  off  the  dangerous  varieties,  Pettenkofer  believed  that  the  greater 
part  of  self -purification  is  due  to  the  growth  of  algae  and  other  low  forms 
of  vegetation  which  clear  the  water  of  its  impurities  in  the  same  way  that 
the  higher  plants  utilize  the  decomposing  manure  on  cultivated  fields. 
This  view  is  endorsed  by  Bokorny,  Emerisch,  and  Briiner  and  others 
who  have  studied  the  question.  It  is  proven  that  these  plants  take 
up  all  manner  of  organic  substances.  This  includes  volatile  fatty 
acids,  amino  acids,  glucose,  and  urea.  The  purifying  effects  of  water 
vegetation  are  therefore  placed  near  the  head  of  the  list  of  self-puri- 
fying agencies. 

Dilution  and  Sedimentation. — Dilution  is  one  of  nature's  real 
sanitary  blessings.  The  superabundance  of  water  and  air  quickly  dilutes 
the  impurities  under  ordinary  conditions  so  as  to  render  them  harm- 
less. A  small  amount  of  infection  in  a  great  volume  of  river  or  lake 
water  soon  becomes  so  diluted  as  literally  to  become  lost.  It  is  true 
that  one  germ  may  cause  disease  just  as  a  spark  may  start  a  forest  fire, 
but  the  conditions  must  be  exceptionally  favorable.  It  is  fortunate  for 
us  that  a  single  typhoid,  cholera,  or  dysentery  bacillus,  especially  when 
attenuated,  may  not,  as  a  rule,  induce  disease.  It  is  further  clear  that 
the  chances  of  receiving  a  single  bacillus  in  the  few  glasses  of  water 
one  drinks  are  mathematically  very  small  when  the  dilution  is  very 
great.  Owing  to  these  facts  and  to  the  further  fact  that  pathogenic 
spore-free  bacteria  soon  become  attenuated  and  die  in  water,  dilution 
becomes  one  of  our  chief  sanitary  safeguards. 

Sedimentation  is  favored  by  a  slow-moving  stream  containing  in- 
soluble inorganic  particles  such  as  clay.  In  muddy  streams  such  as  the 
Mississippi  and  Potomac  Rivers  the  water  is  purified  in  very  much  the 
same  way  that  the  snow  clears  the  air.  The  particles,  constantly  settling, 
wash  the  water  by  enmeshing  the  bacteria,  which  are  thus  carried  to 
the  bottom,  where  they  are  imprisoned  and  die.  It  is  almost  a  filtration 
process.  The  water  is  swept  or  scoured  many  times  by  the  innumerable 
fine  particles  in  a  turbid  stream.  This  is  the  same  principle  used  to 
clarify  water  with  chemical  coagulants  such  as  sulphate  of  alumina. 

Sunlight. — The  germicidal  influence  of  sunlight  exerts  its  power  ' 
upon  all  surface  waters.    The  depth  of  penetration,  however,  varies  with 
the  turbidity  of  the  water,  the  strength  and  direction  of  the  sun's  rays, 
and  other  factors. 

Storage  in  Lakes  and  Ponds. — Nature  makes  use  of  the  purifying 
power  of  time  in  storing  water  in  lakes  and  ponds  and  other  surface 
collections.  Very  few  parasites  pathogenic  for  man  multiply  in  water 
under  natural  conditions.  In  time  they  all  die  out.  Hence  a  stored 
water  is  reasonably  safe.  In  addition,  the  organic  matter  undergoes  decay 
^nd  returns  to  its  simple  mineral  constituents..    Hence  a  stored  water 


882  THE  PURIFICATION  OF  WATER 

will  in  time  free  itself  not  only  of  harmful  parasites,  but  also  of  most 
of  its  organic  pollution.  The  stagnation  of  stored  water  has  been  de- 
scribed on  page  805. 

The  purifying  power  of  the  soil  has  been  fully  discussed  in  connection 
with  the  nitrogen  cycle  (page  773). 


DISTILLED  WATER 

The  distillation  of  water  is  the  only  method  known  for  rendering  it 
pure  in  a  chemical  sense.  From  a  hygienic  standpoint  it  is  ideal;  from 
a  practical  and  economic  standpoint  it  has  several  objections. 

In  the  distillation  of  water  the  first  portion  of  vapor  contains  a 
disproportionate  amount  of  volatile  impurities,  if  such  are  present. 
If  the  distillation  is  continued  to  dryness  or  nearly  so  the  concentrated 
solution  of  mineral  and  organic  matters  suffers  reactions  by  which  more 
volatile  matter  is  formed  and  the  distillate  is  again  contaminated.  For 
these  reasons  standard  distilled  water  usually  includes  only  what  is 
technically  termed  the  ^^middle  run  of  the  still,"  some  of  the  first 
portion  being  rejected  and  the  distillation  stopped  before  all  the  water 
passes  over. 

Distilled  water,  even  when  obtained  with  precautions,  is  not  always 
acceptable  for  drinking  purposes.  The  taste  is  flat  and  suggestive  of 
scorched  organic  matter.  This  is  often  ascribed  to  the  want  of  aera- 
tion, but  in  many  cases  the  sample  is  not  improved  by  thorough  aera- 
tion. Even  when  so  improved,  the  additional  operation  adds  expense, 
and  unless  purified  air  is  used  it  adds  organic  matters  living  and  dead. 
Leffmann  believes  that  the  disagreeable  taste  of  distilled  water  is  often 
due  to  volatile  matters. 

The  economic  production  of  a  high-class  distilled  water  is  to  be 
desired  both  from  a  sanitary  and  technical  point  of  view,  such  as  for 
use  by  brewers  and  makers  of  soft  drinks,  laundries,  paper  mills,  and 
many  other  processes  requiring  clean  and  pure  water. 

Statements  are  occasionally  made  that  distilled  water  is  too  pure  and 
hence  not  well  adapted  for  drinkmg  purposes,  but  these  statements 
are  not  based  upon  physiological  principles  or  clinical  experience. 


BOILED  WATER 

Boiling  renders  water  safe  so  far  as  water-borne  infections  are  con- 
cerned. It  also  destroys  the  toxins  and  probably  renders  most  poisonous 
substances  of  organic  origin  that  may  be  in  the  water  harmless.  Water 
containing  lead  and  other  stable  chemical  substances  injurious  to  health 
would  not,  of  course,  be  rendered  safe  by  boiling. 


FILTERS  883 

For  the  traveler,  the  camper,  and  others  who  must  use  water  of 
various  sources,  the  character  of  which  cannot  be  readily  ascertained, 
the  only  safe  procedure  is  to  have  his  own  tea  kettle  and  little  alcohol 
lamp.  Enough  water  may  be  boiled  in  a  few  minutes  in  the  morning  or 
evening  to  last  twenty-four  hours  or  more  for  personal  use.  Chlorinated 
lime  may  also  be  used  for  this  purpose.     (See  page  900.) 

Boiling  drives  off  the  dissolved  gases,  which  gives  to  boiled  water  a 
flat  taste.  This  may  be  corrected  by  shaking  the  water  in  a  bottle 
or  stirring  with  an  egg-beater,  or  simply  exposing  it  to  the  air  over 
night,  care  being  taken  not  to  recontaminate  it.  The  disagreeable  taste 
of  boiled  water  is  partly  due  to  changes  in  the  organic  matter  which 
take  place  at  100°  C.  As  a  matter  of  fact,  it  is  not  necessary  to  actually 
boil  water  to  render  it  safe  so  far  as  typhoid,  cholera,  dysentery,  and 
other  non-spore-bearing  infections  are  concerned.  A  temperature  of 
60°  C.  for  twenty  minutes  or  70°  C.  or80°C.  for  a  few  moments  is 
sufficient.  However,  in  the  kitchen,  where  thermometers  and  scientific 
care  are  not  expected,  it  is  better  to  require  the  water  actually  to  boil 
to  insure  safety,  especially  in  waters  known  to  be  infected  or  during  epi- 
demics. Boiled  water  may  be  kept  in  covered  pails  or  conveniently 
placed  in  well  stoppered  bottles,  in  which  case  it  may  be  iced  without 
the  risk  of  contamination. 

FILTERS 

Slow  Sand  Filters. — Slow  sand  filters,  also  called  English  filter-beds, 
consist  of  large,  shallow,  tight  reservoirs  suitably  underdrained  and 
containing  some  five  or  six  feet  of  stratified  filtering  material  of  progres- 
sive degrees  of  fineness,  beginning  at  the  bottom  with  broken  stone  or 
gravel  and  ending  with  an  upper  layer  of  fine  sand.  The  water  is 
passed  through  such  a  filter  very  slowly,  from  above  downward,  and 
the  cleansing  is  done  by  removing  the  surface  layer  of  dirty  sand. 

Slowly  passing  water  in  this  way  through  sand  purifies  it  biologically, 
physically,  and  chemically;  nearly  all  of  the  objectionable  bacteria  as 
well  as  other  microorganisms  are  removed  and  many  of  the  particles 
in  suspension  are  strained  out  and  much  of  the  organic  matter  is 
oxidized. 

This  process  is  called  "slow"  sand  filtration  to  distinguish  it  from 

the  rapid  process  known  as  mechanical  filtration.     The  slow  sand  filters 

are  spoken  of  as  the  English  method,  or  as  English  filter-beds,  because 

it  was  in  England  that  they  originated;^  whereas  the  mechanical  filters 

*The  first  recorded  attempt  to  filter  water  through  sand  was  in  1829  when 
the  one-acre  slow  sand  filter  was  built  by  James  Simpson  for  the  East  Chelsea 
Water  Co.,  at  London,  England.  In  1872  a  plant  was  built  at  Poughkeepsie, 
N.  Y.,  in  accordance  with  plans  prepared  by  Mr.  James  P.  Kirkwood,  which 
was  the  first  practical  attempt  at  purification  of  a  municipal  water  supply 
in  America. 


884 


THE  PUEIFICATION  OF  WATEE 


are  spoken  of  as  the  American  method,  because  this  process  was  de- 
veloped in  this  country  to  meet  our  special  needs.  The  student  should 
have  a  clear  comprehension  of  the  differences  between  these  two  methods. 
The  water  in  the  slow  sand  filter  passes  very  slowly  through  a  layer 
of  sand;  the  filter  chokes  by  the  clogging  of  the  superficial  layer  of 
sand,  and  the  cleansing  of  this  type  of  filter  is  done  by  removing  this 
layer  or  Sclimutzdecke,  as  it  is  called.  Mechanical  filtration,  on  the 
other  hand,  consists  in  first  adding  a  coagulant  such  as  sulphate  of 
alumina  and  then  passing  the  water  rapidly  through  a  layer  of  sand. 


Fig.  109. — Section  of  an  English  Filter  Bed. 


The  sand  is  cleansed  mechanically  by  clever  devices  and  by  a  reversed 
current  of  the  water. 

The  slow  filtration  of  water  through  sand  originated  as  an  empiric 
process  imitating  nature's  method  of  purifying  water  as  it  slowly  passes 
through  the  soil.  It  was  used  before  the  chemistry  or  bacteriology  of 
the  process  was  understood.  In  fact,  the  intimate  processes  concerned 
in  slow  sand  filtration  are  not  yet  part  of  our  philosophy.  We  know 
that  the  spaces  between  the  sand  are  enormous  when  compared  with 
the  size  of  bacteria;  nevertheless,  over  99  per  cent,  of  the  bacteria  are 
held  in  the  superficial  layers  of  the  sand.  Nitrification  and  oxidation  of 
organic  matter  also  take  place.  The  process  is  not  a  simple  straining, 
that  is,  a  simple  mechanical  filtration.  It  is  a  "vital"  process  in  which 
bacterial  activity  plays  a  very  large  part.  The  bacteria,  algae,  and  other 
microorganisms  resting  upon  the  upper  layer  of  the  sand  grow  and  form 


FILTEES 


885 


a  zoogleal  mass;  each  grain  of  sand  becomes  coated  with  a  gelatinous 
and  adhesive  growth.  A  continuous  layer  forms  upon  the  surface  a 
carpet-like  mass  which  constitutes  the  Schmutzdecke.  This  Schmutz- 
decke  effectively  holds  back  the  bacteria  in  the  water. 

The  removal  of  the  bacteria  then  is  largely  due  to  the  action  of  the 
bacteria  themselves,  but  a  visible  Schmutzdecke  is  not  essential  for  suc- 
cessful sand  filtration.  In  Hamburg,  Lawrence,  and  other  cities  a  green- 
ish or  brownish,  slimy  Schmutzdecke  is  formed  upon  the  surface  of 
the  sand,  and  gradually  becomes  so  thick  and  dense  as  to  offer  much 
resistance  to  the  passage  of  the  water  itself.  The  Schmutzdecke  is  then 
removed.  This  can  readily  be  done  by  scraping  or  shoveling.  Where  a 
visible  Schmutzdecke  is  not  formed,  as  in  the  Washington  sand  filters, 
it  is  probable  that  the  microorganisms  which  form  a  zoogleal  mass  do 
not  find  favorable  conditions  for  growth.  Nevertheless,  in  this  case 
the  surface  layer  of  the  sand  becomes  clogged  in  the  usual  manner  and 


Fig.  110. — The  Arrangement  of  a  Slow  Sand  Filter. 


the  underlying  sand  is  quite  clean.  The  bacteria  that  escape  the  surface 
action  are  caught  upon  and  stick  to  the  mucilaginous  coating  of  the 
sand  particles,  where  they  perish  as  in  a  trap.  The  experiments  of 
the  Massachusetts  Board  of  Health  at  Lawrence  show  that  filtration  may 
be  as  effective  from  a  bacteriological  standpoint  without  the  visible 
Schmutzdecke  as  with  it. 

Construction  and  Operation. — In  view  of  the  importance  of  the 
subject  the  student  should  be  familiar  with  the  general  principles  and 
some  of  the  details  concerning  the  construction  and  method  of  operating 
a  slow  sand  filter. 

It  is  advisable  to  let  the  water  settle  before  it  is  applied  to  the 
sand  for  the  reason  that  this  prevents  undue  choking  or  clogging  of 
the  filters  and  thus  effects  a  great  economy.  One  of  the  main  items 
in  the  cost  of  maintaining  a  slow  sand  filter  is  the  scraping  of  the  sur- 
face layer  and  the  washing  of  the  dirty  sand.  There  are  several  pre- 
liminary methods  of  treating  the  water  before  it  is  applied  to  the  filter. 
These  methods  differ  with  the  character  of  the  vrater,  and  consist  in  the 
main  of  screening,  scrubbing,  or  coagulation.  These  processes  are  dis- 
cussed more  in  detail  upon  another  page. 

A  slow  sand  filter  requires  an  extensive  tract  of  land,  for  it  should  be 
recalled  that  only  two  and  one-half  to  five  million  gallons  of  water  should 


886  THE  PUKIFICATION  OF  WATER 

be  filtered  per  acre  per  day.  The  filter  should  be  conveniently  located 
near  the  community  it  is  to  serve,  and  the  high  price  of  urban  property 
is  an  important  economic  consideration.  Thus,  in  Washington  it  re- 
quires 21  acres  alone  for  the  filter  beds  to  furnish  63,000,000  gallons  of 
water  daily  at  a  3-million-gallon  rate  per  acre.  The  settling  basins,  stor- 
age basins  for  the  filtered  water,  sand-washing  apparatus,  pumping  sta- 
tion, laboratory,  and  other  accessories  require  considerably  more  land. 
The  entire  filtering  surface  is  divided  into  units  known  as  filter-beds. 
The  size  of  each  filter-bed  has  grown  with  the  development  of  the  art. 
In  the  filters  recently  constructed  each  bed  occupies  about  one  acre. 
Each  bed  must  be  an  independent  unit,  so  that  the  rate  of  filtra- 
tion, the  cleaning  and  all  other  operations  may  be  carried  on  without 
disturbing  the  other  beds.  The  pipes  carrying  the  effluent  from 
each  filter-bed  must  be  so  arranged  that  the  water  may  be  wasted  or 
utilized.  Where  the  climate  is  cold,  filters  should  be  covered  to  prevent 
freezing. 

In  construction  a  filter-bed  is  built  very  much  like  an  ordinary  re- 
inforced concrete  reservoir.  The  bottom  and  sides  must  be  water-tight, 
for  failure  in  this  regard  may  be  annoying  and  dangerous  for  the  reason 
that  there  may  be  considerable  loss  of  filtered  water  or  entrance  of  pollu- 
tion from  the  outside  if  the  pressure  is  reversed.  The  sides  of  the  bed 
are  usually  vertical,  although  it  is  some  advantage  to  make  them  slanting 
or  with  horizontal  ledges  in  order  to  diminish  leaks. 

The  sand  may  be  obtained  from  a  river  bed  or  from  sand  banks; 
the  grains  should  be  sharp,  hard  silicates.  If  the  sand  contains  clay 
this  should  be  removed  by  washing  before  it  is  used.  It  is  also  im- 
portant that  the  filtering  sand  should  be  free  from  lime,  which  has  a 
tendency  to  make  the  water  hard.  The  average  diameter  of  the  sand 
best  suited  usually  varies  from  0.2  to  0.3  millimeter.  It  is  especially 
important  that  the  particles  should  be  mainly  of  the  same  size.  This  is 
determined  by  establishing  the  coefficient  of  uniformity. 

The  sand  used  for  filtration  contains  particles  of  various  sizes;  the 
water  is  forced  around  the  larger  particles  and  through  the  finer  inter- 
stices which  occupy  the  intervening  spaces,  so  that  it  is  the  finest  por- 
tion which  mainly  determines  the  efiiciency  of  the  sand  for  filtration. 
According  to  Hazen,  a  provisional  basis  which  best  accounts  for  the 
known  facts  considers  the  size  of  grain  such  that  10  per  cent,  by  weight 
of  the  particles  are  smaller  and  90  per  cent,  larger  than  itself.  This 
is  considered  the  effective  size,  and  is  determined  by  sifting  a  weighed 
amount  of  the  sand  through  a  series  of  sieves.  Another  important  point 
in  regard  to  the  sand  is  its  degree  of  uniformity;  that  is,  whether  the 
particles  are  mainly  of  the  same  size  or  whether  there  is  a  great  range 
in  their  diameters.  This  is  shown  by  the  uniformity  coefficient,  a  term 
used  to  designate  the  ratio  of  the  size  of  grain  which  is  60  per  cent. 


FILTEES  887 

of  the  sample  finer  than  itself  to  the  size  which  is  10  per  cent,  finer  than 
itself. 

The  usual  thickness  of  the  sand  layer  varies  from  12  to  48  inches. 
The  Imperial  Board  of  Health  of  Germany  has  fixed  13  inches  as  the 
limit  below  which  the  sand  should  never  be  scraped.  The  higher  limit 
is  advisable  wherever  practicable.  In  this  country  the  usual  depth  of  the 
sand  layer  is  about  3  feet,  and  this  is  reduced  by  successive  scrapings 
for  the  purpose  of  cleaning  until  it  approaches  12  inches,  when  the 
sand  is  replaced.  A  thick  sand  layer  has  a  steadying  action  upon  the 
water  on  account  of  the  increased  friction,  and  thus  aids  in  preventing 
irregularities  in  the  rate  of  filtration. 

The  sand  rests  upon  a  stratified  layer  of  rock  and  gravel  laid  in 
graded  sizes  which  supports  it  so  that  it  does  not  work  its  way  down  into 
the  underdrains. 

The  size,  position,  and  nature  of  the  underdrains  are  a  very  essential 
part  of  the  construction  of  a  slow  sand  filter.  The  underdrains  must 
be  set  so  that  the  rate  of  filtration  will  be  the  same  in  all  parts  of  the 
filter.  If  this  part  of  the  apparatus  is  not  properly  designed  in  a  filter- 
bed  having  the  broad  expanse  of  an  acre  the  water  may  pass  through 
the  sand  in  certain  portions  at  the  rate  of  ten  or  more  million  gallons 
while  it  may  be  found  that  at  other  portions  there  is  practically  no  flow 
at  all. 

The  depth  of  the  water  above  the  sand  is  usually  3  feet.  In 
European  filters  the  depth  varies  from  3  feet  to  52  inches.  It  is  com- 
paratively easy  through  simple  mechanical  devices  to  regulate  the  flow 
of  the  applied  water  so  that  the  depth  of  the  water  above  the  sand  will 
remain  uniform. 

Probably  the  most  important  factor  in  the  operation  of  a  slow  sand 
filter  is  the  rate  of  filtration.  The  tendency  has  been  to  gradually  re- 
duce the  rate  during  the  past  thirty  years.  In  this  country  sand  filters 
are  usually  run  at  a  rate  of  about  2,500,000  to  3,000,000  gallons  per 
acre  per  day.  Three  million  gallons  is  the  maximum  rate  commonly 
allowed.  During  times  of  stress,  however,  or  for  other  reasons,  the 
rate  is  sometimes  speeded  up  to  five  or  six  million  gallons  per  acre 
daily.  In  Hamburg  the  filters  are  not  allowed  to  run  faster  than 
1,600,000  gallons,  and  in  Berlin  2,500,000  gallons.  Water  passed 
through  sand  at  the  rate  of  4,800,000  gallons  per  acre  daily  has  a 
vertical  movement  of  3.94  inches  in  an  hour.  When  the  rate  is  2,400,000 
gallons  the  vertical  motion  is  1.97  inches  per  hour,  and  when  the  rate 
is  slower  the  vertical  motion  is  correspondingly  diminished.  It  will 
thus  be  seen  that  this  process  is  well  named  in  that  the  water  passes 
very  slowly  through  the  filter.  This  is  of  fundamental  importance  be- 
cause the  hour  or  more  during  which  the  water  rests  upon  the  surface 
of  the  sand  and  passes  through  the  superficial  layer  is  the  critical  time 


THE  PURIFICATION  OF  WATER 


Inlet 


Overflow 


when  the  bacteria  are  enmeshed  in  the  Schmuizdecke  or  arlhere  to  the 
particles  of  sand  and  the  other  biological  and  chemical  processes  take 
plaCe.  The  tendency  of  engineers  is  to  increase  the  rate  of  filtration 
on  account  of  the  evident  economy;  the  tendency  of  sanitarians  is  to 
diminish  it  so  as  to  keep  well  within  the  factors  of  safety.  If  hypo- 
chlorite is  added  to  the  filtered  water  there  is  no  objection  to  speeding 
up  the  rate  of  the  filter.  The  rate  of  filtration  may  be  governed  by 
automatic  devices  or  may  be  controlled  by  hand  by  simply  regulating 
the  valve  which  governs  the  pipe  carrying  the  effluent  from  each  filter- 
bed.  The  friction  of  the  sand  layer  varies  from  time  to  time,  so  that 
icareful  attention  is  required  in  order  to  maintain  a  steady  flow  and  a 
iconstant  rate,  which  is  essential,  for  sudden  variations  in  rate  are  fatal 
to  the  successful  purification  of  water  by  the  slow  sand  process. 

The  friction  of  the  sand  is  measured 
by  the  loss  of  head.  The  loss  of  head  is 
the  difference  between  the  level  of  the 
water  above  and  below  the  sand  layer 
measured  in  water  gauges.  This  loss 
represents  the  friction  or  resistance  of 
the  sand  layer.  It  greatly  increases  as 
the  filter  clogs  up.  When  a  filter  is  new 
or  perfectly  clean  the  loss  of  head  is 
usually  about  0.3  foot  or  less;  when  it 
exceeds  4  feet  the  rate  of  filtration 
cannot  be  maintained  at  3,000,000 
gallons  per  acre  daily  with  the  devices 
provided,  and  the  filters  must  be 
cleaned. 

The  length  of  time  a  filter  may  run  before  the  loss  of  head  becomes 
so  great  that  it  becomes  unprofitable  and  requires  cleaning  varies  from 
a  few  days  to  many  months.  The  time  depends  upon  the  character  of 
the  water,  the  rate  of  filtration,  and  temperature,  the  formation  of 
ihe  Sclimutzdeclce  and  many  other  factors.  In  cleaning  a  filter  it  is  suffi- 
cient to  scrape  off  only  enough  sand  to  a  layer  that  appears  clean.  As 
a  rule  the  sand  immediately  below  the  surface  is  not  apparently  soiled, 
and  usually  it  is  not  necessary  to  take  off  more  than  an  inch  or  so  of 
the  surface  layer.  This  sand  is  removed  to  special  cleaning  devices, 
where  it  is  thoroughly  washed  with  filtered  water  and  then  stored  in 
bins  and  replaced  when  the  sand  layer  reaches  a  depth  of  about  12 
inches.  The  Schmutzdecke  and  the  surface  layers  of  the  sand  are 
usually  removed  by  hand  with  broad  shovels.  There  are  also  mechanical 
devices  which  accomplish  the  same  purpose.  After  cleansing,  the  efflu- 
ent from  a  filter-bed  should  be  wasted  until  the  bacteriological  examina- 
tion shows  that  the  filter  is  again  performing  efficient  work.    This  may 


::\San<i:. 


Filtered 


^n^A9,oo^o.9';;6.^.°„''„°°°^°a:=^  Heater 


Fig.  111. — Diagram  Illustrating 
"Loss  OF  Head." 


FILTEES  889 

require  several  days,  the  time  varying  with  the  temperature  and  other 
conditions. 

Efficien^cy  and  Control  of  Slow  Sand  Filters. — The  efficiency 
of  a  slow  sand  filter  is  mainly  measured  by  a  comparison  of  the  number 
of  bacteria  in  the  raw  and  filtered  water.  A  good  filter  should  eliminate 
approximately  99  per  cent,  of  the  bacteria,  provided  the  applied  water 
is  grossly  polluted.  In  any  event  the  filtered  water  should  not  contain 
over  100  bacteria  per  cubic  centimeter  and  very  few  colon  bacilli.  It 
is  to  be  noted  that  all  the  bacteria  in  the  filtered  water  do  not  represent 
those  that  actually  pass  through  the  sand.  Some  of  them  grow  in  the 
underdrains  and  gravel  layer  and  are,  so  far  as  known,  harmless  varieties. 

In  Germany  the  rate  of  filtration  and  other  factors  are  minutely 
regulated  and  controlled  by  official  ordinances.  In  this  country  the 
operation  of  the  filter  is  left  to  the  individual  caprice  of  the  engineer 
in  charge. 

A  slow  sand  filter  cannot  be  effectively  operated  without  skilled 
superintendence  of  an  engineer  expert  in  the  art  of  water  purification. 
It  also  requires  a  small  laboratory  with  a  competent  bacteriologist,  who 
must  make  daily  observations  of  the  applied  water  and  the  effluent 
from  each  filter.  The  effluent  from  a  filter  not  giving  good  results 
should  be  wasted.  The  water  from  a  new  filter,  or  one  just  scraped, 
should  not  be  used  until  the  bacterial  results  show  that  it  is  accom- 
plishing effective  purification. 

There  are  many  ways  in  which  purer  water  may  be  secured,  such  as 
the  use  of  lower  rates  of  filtration,  finer  grained  filtering  materials,  and 
more  complete  preliminary  treatment,  such  as  settling  basins,  storage, 
or  chemical  coagulation.  The  filtered  WLter  may  be  further  purified 
with  hypochlorite  of  lime  or  ozone.  It  requires  a  surprisingly  small 
amount  of  hypochlorite  to  practically  sterilize  a  filtered  water.  In  Pitts- 
burgh 0.13  part  of  bleaching  powder  (measiired  as  available  chlorin) 
per  million  parts  of  water  is  sufficient  for  this  purpose. 

Because  slow  sand  filtration  has  achieved  such  marked  success  with 
some  waters  and  greatly  reduced  the  amount  of  typhoid  is  no  reason 
why  it  should  be  universally  recommended  under  all  circumstances.  To 
recommend  slow  sand  filtration  in  all  cases  would  be  as  irrational  as 
to  recommend  the  use  of  antitoxin  in  every  case  of  sore  throat.  A 
correct  diagnosis  is  essential.  Every  water  cannot  be  successfully  or 
economically  treated  by  this  process  alone.  Thus,  the  very  turbid  waters 
of  our  South  and  West  contain  particles  of  clay  so  fine  that  they  pass 
a  sand  filter.  No  amount  of  sand  filtration  will  take  out  some  of  these 
particles.  The  Potomac  water  in  times  of  high  turbidity  may  be 
passed  through  a  sand  filter  three  or  four  times  without  removing  the 
residual  turbidity  due  to  these  microscopic  particles.  To  apply  a  very 
turbid  water  to  a  sand  filter  soon  chokes  it  and  adds  unnecessarily  to 


890 


THE  PUKIFICATION  OF  WATEE 


the  difficulty  and  expense  of  the  process.  Tlie  particles  may  he  so  fine 
that  they  will  not  all  settle  even  when  the  water  is  given  long  storage. 
There  are  several  ways  of  solving  this  problem,  which  is  of  first  magni- 
tude for  the  purification  of  the  surface  water  of  a  large  part  of  our 
country.  One  of  the  best  ways  is  to  provide  large  storage  reservoirs, 
so  that  the  water  may  be  taken  from  the  river  only  at  favorable  times, 
rejecting  the  flow  during  periods  of  high  turbidity.  Another  is  to  use 
preliminary  coagulation  with  aluminium  sulphate  and  provide  for  sedi- 
mentation before  applying  the  water  to  the  sand.  Much  of  the  turbidity 
may  be  removed  by  a  rapid  preliminary  filtration  through  some  coarse 
material  such  as  charcoal,  sponge,  etc.  This  process  is  known  as  scrub- 
bing. No  general  rule  can  be  set  down.  Waters  differ  radically,  and 
the  same  stream  varies  from  time  to  time.  Each  problem  must  be 
studied  and  solved  in  relation  to  its  own  special  condition.  Whether 
the  filtered  water  should  be  further  purified  with  bleaching  powder  or 
ozone  depends  upon  circumstances. 

Eesults  of  Slow  Sand  Eilteation. — The  following  cities  purify 
their  water  supply  by  slow  sand  filtration )  : 

Ldst  of  cities  using  slow  sand  filtration 


Place 


Population 
in  1910 


Capacity  of  Filters 
in  Gallons  per  Day 


Philadelphia. 
Pittsburgh.  . 

Toronto 

Washington . 
Indianapolis . 


Providence . 
Denver.  .  .  . 
New  Haven . 
Albany.  .  .  . 
Reading .... 


Springfield. 
Wilmington . 
Lawrence.  . 
Yonkers. . . . 
Superior.  .  . 


Mount  Vernon 

Poughkeepsie 

And  20  or  30  smaller  places 


1,594,008 
533,905 
376,538 
331,069 
233,650 

224,326 
213,381 
133,605 
100,253 
96,071 

88,926 
87,411 
85,892 
79,803 
40,384 

30,919 
27,936 


420,000,000 

100,000,000 

60,000,000 

87,000,000 

24,000,000 

24,000,000 
30,000,000 
15,000,000 
17,000,000 
22,000,000 

15,000,000 
15,000,000 

6,000,000 
10,000,000 

5,000,000 

3,000,000 
5,000,000 


Hazen's  Clean  Water  and  how  to  get  it,  2nd  edition,  1914. 

The  good  results  of  purifying  water  by  the  slow  sand  method  have 
been  abundantly  demonstrated  in  Altoona,  near  Hamburg,  in  1892,  dur- 
ing the  cholera  epidemic;  also  in  Hamburg  since  1893  and  in  Lawrence 
also  since  1893 ;  further  in  Albany,  Philadelphia,  Pittsburgh,  Berlin, 
Paris,  and  many  English  cities.  It  should  be  noted  especially  at  Albany 
that  the  typhoid  rate  did  not  come  down  immediately  after  filtration.    It 


FILTEES  891 

sometimes  requires  one  or  two  years  to  reach  the  residual  or  "normal" 
rate.  In  a  few  instances,  such  as  Washington,  D.  C,  and  Youngstown, 
0.,  filtration  of  the  water  was  not  followed  by  a  noticeable  diminution  in 
the  typhoid  rates. 

The  best  results  in  water  purification,  as  measured  by  the  improve- 
ment in  the  health  and  reduction  of  the  death  rate  among  those  who 
use  the  water,  have  been  obtained  with  slow  sand  filters.  Hazen  believes 
that  this  is  probably  because  the  method  is  an  old  one,  has  been  long 
and  carefully  studied,  and  has  been  applied  on  a  large  scale  in  well- 
perfected  forms  for  many  years,  rather  than  to  any  natural  superiority 
of  the  method. 

The  purification  of  water  through  slow  sand  filtration  not  only 
diminishes  the  amount  of  typhoid  and  other  water-borne  intestinal  in- 
fections, but  is  believed  also  to  reduce  the  general  death  rate.  This  fact, 
known  as  the  Mills-Eeinecke  phenomenon,  is  discussed  on  page  913. 

Mechanical  Filters. — The  essential  and  characteristic  features  of 
mechanical  filtration  are:  (1)  The  addition  of  a  chemical  precipitant 
or  coagulant  to  the  water,  and  (2)  then  passing  the  water  rapidly 
through  a  layer  of  sand.  The  filtering  sand  is  contained  in  a  large 
wooden,  iron,  or  concrete  tank  so  arranged  that  it  can  be  mechanically 
washed.^  These  filters  are  well  named,  not  only  because  the  filtering 
sand  is  washed  mechanically,  but  because  the  action  is  more  strictly  a 
mechanical  straining,  whereas  biological  processes  are  the  main  features 
in  the  purification  of  water  passing  through  a  slow  sand  filter.  In 
the  Hyatt  and  Jewell  filters  the  sand  is  agitated  by  a  revolving  rake 
as  the  reversed  flow  of  water  washes  the  sand.  In  the  Continental  type 
the  sand  is  agitated  by  compressed  air. 

The  coagulants  commonly  used  are  sulphate  of  aluminium,  some- 
times alum,  occasionally  sulphate  of  iron.  The  alkaline  carbonates 
present  in  the  water  decompose  the  aluminium  sulphate  with  the  forma- 
tion of  aluminium  hydrate,  which  is  thrown  out  of  the  solution  as  a  floc- 
culent,  colloidal,  jelly-like  precipitate.    The  reaction  is  as  follows : 

Al2(S0j3  +  3Ca(C03)  =  AL(C03)3  -f  BCaSO^ 
AI2  (003)3  +  6H2O  =  2A1(0H)3  +  3H2O  +  3CO2 

The  calcium  carbonate  is  necessary  to  break  up  the  alum,  and  if  not 
normally  present  in  the  water  some  lime  or  soda  must  be  added.  The 
reactions  and  methods  of  estimating  the  quantities  are  given  in  detail  on 
page  907.  The  precipitated  aluminium  hydrate  clears  the  water  very 
much  as  white  of  egg  clears  coffee.  Suspended  matter,  including  bacteria  , 
and  inorganic  particles,  are  enmeshed  and  deposited  on  the  surface  of  " 

*  Mechanical  filters  date  from  1884,  when  the  process  was  patented  by  J.  W. 
Hyatt  and  Professor  Albert  R.  Leeds.  The  Hyatt  patent  expired  in  1901,  and 
since  then  numerous  improvements  in  details  have  been  made  and  patented, 
considesrably  improving  the  art  of  cleaning  water  tlirough  tliis  process. 


893  THE  PUKIFICATTON  OF  WATEE 

the  sand.  When  this  deposit  heconies  abuiidant  cMiougli  to  clog  the  filter 
the  filter  is  washed  by  reversing  the  flow  and  mechanically  agitating  the 
sand.  Thus  it  will  be  seen  that  an  artificial  inorganic  Schmutzdecke  is 
produced  upon  mechanical  filters  instead  of  the  natural  organic  Schmutz- 
decke of  the  slow  sand  filter-bed. 

It  is  advisable  to  provide  coagulating  basins  to  hold  the  water  for 
a  short  time  after  it  has  received  the  coagulant,  in  order  to  allow  the 
chemical  reaction  resulting  from  the  treatment  to  take  place.  Such 
basins  also  serve  to  remove  by  sedimentation  the  greater  part  of  the 
precipitate,  and  the  filters  therefore  do  not  clog  so  readily,  and  cleans- 
ing is  not  required  so  frequently. 

The  rate  at  which  water  is  passed  through  mechanical  filters  is  very 
great  when  compared  with  slow  sand  filters.  Eates  varying  from  100,- 
000,000  to  150,000,000  gallons  per  acre  per  day  are  used. 

One  hundred  and  twenty-five  million  gallons  per  acre  daily  may  be 
taken  as  a  fair  average  of  what  is  to  be  expected  of  them.  On  account 
of  the  rapid  rate  of  filtration  there  is  great  economy  of  space.  However, 
while  the  mechanical  filters  are  cheaper  when  first  cost  is  considered, 
the  advantage  is  with  slow  sand  filters  as  far  as  cost  of  maintenance  is 
concerned. 

The  proper  amount  of  coagulant  is  added  to  the  water  by  means 
of  a  small  automatic  measuring  apparatus.  It  requires,  as  a  rule, 
about  one  or  two  grains  of  alum  or  sulphate  of  aluminium  for  each  gallon 
of  water  to  be  treated.  The  amount  of  alum  added  to  the  water  must 
vary  from  time  to  time,  depending  upon  the  turbidity,  the  reaction, 
and  also  upon  the  amount  of  calcium  carbonate  in  the  water.  The 
turbidity  and  composition  of  many  of  our  streams  vary  suddenly  and 
require  a  watchful  eye.  If  too  little  alum  is  added  the  effluent  will  not 
be  clear;  if  too  much  is  used  the  effluent  will  contain  the  excess  of  alum 
in  solution.  Mechanical  filters,  therefore,  require  intelligent  and  con- 
stant supervision  in  order  to  furnish  satisfactory  results. 

Mechanical  filtration  meets  with  special  favor  in  this  country  be- 
cause it  aifords  a  comparatively  cheap  method  of  supplying  a  clean- 
looking  water  from  a  very  turbid  source.  The  process  is  particularly 
applicable  to  the  muddy  streams  of  our  South  and  West.  In  fact,  it  is 
the  only  known  method  of  rendering  some  of  these  waters  quite  free 
of  turbidity. 

Mechanical  filters,  when  properly  manipulated,  will  take  out  from 
95  to  99  per  cent,  of  the  bacteria  contained  in  the  raw  water.  The 
bacterial  purification,  however,  is  not  as  constant  and  uniformly  high 
as  that  obtained  by  slow  sand  filtration.  The  aluminium  hydrate  also 
takes  out  much  of  the  soluble  coloring  matter  which  the  water  may 
contain,  as  well  as  its  turbidity. 

Judged  by  the   effects   upon   morbidity  and  mortality,  mechanical 


FILTERS 


893 


filtration  of  water  has  in  no  instance  given  the  same  satisfactory  results 
afforded  by  slow  sand  filtration.  Most  of  the  mechanical  filters  in  use 
in  America  have  fallen  far  short  in  hygienic  efficiency.  This  was  espe- 
cially true  with  the  old  and  inferior  plants  which  often  were  without 
skilful  supervision.  According  to  Hazen,  the  mechanical  filters  that 
have  taken  advantage  of  all  the  improvements  in  construction  and  that 
are  operated  with  skill  and  experienced  superintendence  are  doing  as 
good  work,  measured  by  bacterial  efficiency,  as  the  corresponding  slow 
sand  filters,  and  Hazen  believes  that  in  time  the  hygienic  efficiency  will 
show  corresponding  results  from  them. 

The  Diffeeence  Between  Slow  Sand  and  Mechanical  Filtration 


Slow  Sand  Filtration 

English  system  or  English  filter-beds 
— originated  in  England. 

Has  been  long  in  use  and  effective- 
ness is  established. 


Preliminary  treatment  not  an  essen- 
tial part  of  the  process,  though 
sometimes  desirable. 

Water  passes  slowly  through  a  layer 
of  sand,  in  large,  shallow,  tight 
reservoirs. 

Usual  rates  from  1,600,000  to  5,000,- 
000  gallons  per  acre  per  day. 


Cleaned  by  scraping  surface  layer  of 
sand — Schmutzdeche. 


The  process  is  mainly  biological, 
partly  a  mechanical  straining. 
Duplicates  nature's  process  of 
purifying  water. 

First  cost  is  large;  maintenance 
comparatively  small. 

Especially  serviceable  for  water  hav- 
ing little  turbidity. 

Removes  about  one-third  of  the 
coloring  matter. 

Removes  about  99  per  cent,  of  the 
bacteria;  action  is  uniform. 


Favorable  effect  upon  health  demon- 
strated. 


Mechanical  Filtration 

American  system  —  developed  in 
America  to  meet  our  special  needs. 

Comparatively  recent  (since  1884), 
and  effectiveness  not  yet  estab- 
lished. 

A  coagulant  is  first  added  to  the 
water — sulphate  of  aluminium, 
alum,  or  sulphate  of  iron. 

Water  passes  rapidly  through  a  layer 
of  sand  in  small  wooden,  concrete, 
or  iron  tanks. 

Usual  rates  100  to  200  times  as  rapid 
—100,000,000  to  150,000,000  or 
more  gallons  per  acre  daily. 

Cleaned  by  reversed  flow  of  water 
and  mechanical  agitation  of  the 
sand — hence  the  name  "mechani- 
cal" filtration. 

The  process  is  mainly  a  mechanical 
straining.  An  artificial  imitation 
of  nature's  process. 


First  cost  is  comparatively  small; 
maintenance  large.   . 

Especially  suitable  for  turbid  waters, 
containing  silt  and  clay. 

Takes  out  nearly  all  of  dissolved 
coloring  matter. 

When  properly  operated  removes 
from  95  to  99  per  cent,  of  bac- 
teria— less  uniform. 

Hygienic  efficiency  not  established, 
but  doubtless  would  be  more  sat- 
isfactory if  well  operated. 


894 


THE  PURIFICATION  OF  WATER 


The  following  is  a  partial  list  compiled  hy  Hazen  of  places  in  the 
United  States  where  mechanical  filters  are  at  present  in  use  or  under 
construction : 


Cincinnati,  Ohio  ^ 

New  Orleans,  La.  ^ 

East  Jersey  Water  Company. 
Hackensack  Water  Company . 
Louisville,  Ky.  ^ 


Toledo,  Ohio  ^ .  . 
Columbus,  Ohio  ^ 
St.  Joseph,  Mo.. 

Atlanta,  Ga 

Charleston,  S.  C. 


Kansas  City,  Kan. 
Harrisburg,  Penn. . 

Norfolk,  Va _. . 

Youngstown,  Ohio. 
Bingham  ton,  N.  Y . 


Augusta,  Ga 

Birmingham,  Ala. 
Little  Rock,  Ark . 
Terre  Haute,  Ind. 
Dubuque,  Iowa. . 


Quincy,  lU 

Elmira,  N.  Y 

Davenport,  Iowa. 
Chester,  Penn.  .  . 
York,  Penn 


KnoxviUe,  Tenn  — 
Chattanooga,  Tenn. 
East  St.  Louis,  111. . 
Newcastle,  Penn .  .  . 
Oshkosh,  Wis 


Lexington,  Ky , 

Joplin,  Mo 

Cedar  Rapids,  Iowa . 


Population,  1900 

i^apacity  or  f  iirers 
in  Gallons  per  Day 

325,902 
287,104 

112,000,000 
44,000,000 

250,000 
225,000 
204,731 

32,000,000 
24,000,000 
37,500,000 

131,822 
125,560 
102,979 

89,872 
55,807 

20,000,000 

30,000,000 

11,000,000 

6,000,000 

5,000,000 

51,418 
50,167 
46,624 

44,885 
39,647 

6,500,000 
12,000,000 

8,000,000 
10,000,000 

8,000,000 

39,441 
38,415 
38,307 
36,673 
36,297 

36,252 
35,672 
35,254 
33,988 
33,708 

6,000,000 

5,500,000 
9,000,000 

4,000,000 
7,000,000 
7,000,000 
4,000,000 
4,000,000 

32,637 
30,154 
29,655 
28,339 

28,284 

4,500,000 
9,000,000 
11,000,000 
4,000,000 
2,000,000 

26,369 
26,023 
25,656 

3,500,000 

2,500,000 

And  fully  125  smaller  places. 
»  Building. 

In  1900,  according  to  Hazen,  1,860,000  people,  or  6.3  per  cent,  of 
the  urban  population  of  the  United  States,  were  being  supplied  with 
filtered  water.  In  1904  the  number  of  people  so  supplied  had  increased 
to  3,160,000  or  9.7  per  cent,  of  the  urban  population  of  the  country. 
Since  that  time  many  large  cities  have  installed  filter  plants,  until 
(1913)  about  8,000,000  people,  or  over  20  per  cent,  of  the  urban  popu- 
lation, are  being  served  with  filtered  water.  Much  of  this  filtered  water 
is  now  also  treated  with  bleaching  powder. 

Household  Filters. — The  domestic  filter  as  ordinarily  used  in  the 


FILTEES  895 

household  has  limited  sanitary  value.  The  purification  of  water,  even  by 
so  simple  a  method  as  straining,  requires  a  degree  of  care,  knowledge, 
and  experience  that  is  not  found  in  the  kitchen.  If  a  water  is  infected, 
reliance  should  not  be  placed  upon  any  household  filter  operated  iu 
the  usual  way.  It  is  possible  in  the  laboratory  by  the  use  of  special 
precautions  to  pass  water  through  a  Pasteur-Chamberland  or  a  Berkefeld 
filter  so  as  to  obtain  a  sterile  filtrate.  This  requires  skilled  bacteriolog- 
ical manipulation  of  a  kind  that  cannot  be  attained  in  ordinary  service 
in  the  house.  I  have  seen  janitors  "clean"  a  filter  in  such  a  way  as  to 
actually  contaminate  the  water. 

There  are  two  main  types  of  household  filters :  one  made  of  unglazed 
porcelain  (kaolin),  known  as  the  Pasteur-Chamberland,  and  the  other 
made  of  diatomaceous  earth,  the  Berkefeld.  Even  in  the  closest  grained 
unglazed  porcelain  filter  the  pores  of  the  filter  are  larger  than  the  bac- 
teria. The  bacteria  do  not  get  through  on  account  of  the  tortuous  pas- 
sage; they  adhere  to  the  particles  that  make  up  the  filtering  sub- 
stance. But  if  conditions  are  favorable,  bacteria,  such  as  typhoid,  may 
soon  grow  through  its  walls.  The  Berkefeld  filters  of  diatomaceous 
earth  are  more  porous  than  the  Pasteur-Chamberland  filters. 

When  a  water  is  not  infected,  but  turbid,  household  filters  are  ser- 
viceable in  rendering  it  clear.  They  are  specially  useful  when  the  tur- 
bidity is  due  to  clay  or  to  iron,  or  other  inorganic  particles  that  may 
readily  be  removed  by  simple  straining. 

The  sanitarian  places  no  reliance  upon  the  filtration  of  water  in 
the  household,  and  for  drinking  purposes  such  water,  if  infected,  whether 
filtered  or  not,  should  be  boiled.    The  boiling  should  be  the  last  process. 

Filters  of  natural  stone,  charcoal,  asbestos,  and  a  great  variety  of 
porous  substances  are  on  the  market  for  domestic  use.  These  filters 
may  be  useful  in  cleaning  water  that  is  turbid,  but  they  cannot  be  de- 
pended upon  to  purify  an  infected  supply. 

Scrubbing  or  Roughing  Filters. — Scrubbers  are  rapid  coarse-grained 
filters  through  which  turbid  water  is  passed  at  a  very  high  rate  in 
order  to  remove  coarser  particles  and  some  of  the  turbidity.  This 
process  of  scrubbing  the  water  is  principally  used  as  a  preliminary 
to  sand  filtration.  It  is  designed  to  protect  the  sand  filters  from  clog- 
ging up  too  quickly  and  thus  economize  the  operation.  Scrubbers,  also 
known  as  roughing  filters,  consist  of  some  porous  substances  such  as 
sponge,  coke,  and  lava.  The  principal  difficulty  connected  with  a  scrub- 
ber is  an  efficient  and  economical  device  for  cleaning  them,  which  must 
be  done  at  frequent  intervals. 

Screening  or  straining  is  used  particularly  to  remove  fish  and  floating 
leaves,  sticks,  etc.  Screens  may  consist  of  steel  bars  arranged  so  that 
they  may  be  easily  raked  off,  or  of  wire  cloth  arranged  in  pairs,  so  that 
while  one  screen  is  raised  for  cleaning  its  mate  is  below  in  service. 


896  THE  PURIFTCATION  OF  WATEE 

Eevolving  screens  are  efficient.  The  motion  should  be  continuous,  and 
the  cleaning  is  done  on  that  part  of  the  screen  above  the  water  by  jets 
of  water  playing  upon  it.  Screening  is  of  no  service  in  removing  algae 
or  microorganisms,  and  can  only  be  depended  upon  to  remove  the 
coarse  particles,  and  is  only  necessary  where  the  water  contains  such 
material. 

STORAGE 

The  storage  of  water  is  one  of  the  simplest  and  best  means  of  purify- 
ing it.  The  first  cost  may  be  large,  but  the  cost  of  maintenance  is  com- 
paratively trifling.  Harmful  bacteria  soon  die  in  a  stored  water,  the 
solid  particles  settle  out,  the  organic  matter  is  largely  oxidized,  the 
color  is  gradually  bleached,  and  other  improvements  take  place.  Storage 
takes  advantage  of  many  of  nature's  methods  of  purifying  water,  viz., 
time,  sunlight,  dilution,  sedimentation,  oxidation,  and  symbiosis. 

A  stored  water  may  deteriorate  in  quality  owing  to  the  growth  of 
algae  and  the  decomposition  of  organic  matter.  Algae  and  diatoms 
grow  in  stored  water  exposed  to  sunlight,  particularly  in  warm  weather. 
While  these  organisms  are  not  harmful,  they  impart  disagreeable  tastes 
and  odors  to  the  water.  (See  page  823.)  The  decomposition  of  the 
organic  matter  in  a  storage  water  may  also  cause  unpleasant  tastes 
and  odors,  especially  at  the  spring  and  fall  overturn.  (See  page  805.) 
Waters  stored  in  a  closed  reservoir  keep  without  deterioration,  and  the 
advantage  is  therefore  manifest.  Filtered  water  should  always  be  stored 
in  covered  reservoirs,  not  only  to  protect  it  from  strong  light,  but  also 
to  prevent  contamination  from  dust  and  other  sources. 


SEDIMENTATION 

Sedimentation  is  of  limited  use  in  improving  the  sanitary  quality  of 
a  water.  Sedimentation  basins  are  frequently  used  as  a  preliminary 
process  in  water  purification.  It  is  the  cheapest  way  of  removing  rela- 
tively large  particles  which  will  settle  out  in  a  moderately  short  time. 
There  is  also  a  sanitary  advantage  in  that  the  suspended  particles  me- 
chanically carry  down  with  them  some  of  the  bacteria.  The  water, 
as  a  rule,  does  not  remain  in  the  sedimenting  basins  long  enough  to 
obtain  the  full  effects  of  storage. 

Sedimentation  is  a  very  important  factor  in  the  bacterial  purification 
of  flowing  streams.  The  effect  of  sedimentation  is  most  manifest  when 
the  flow  of  water  is  rapid  enough  to  prevent  accumulation,  at  any  point, 
of  the  products  of  bacterial  multiplication,  but  not  so  rapid  as  to  inter- 
fere with  a  comparatively  rapid  action  of  gravity.     Turbid  streams 


CHEMICAL  METHODS  OF  PUETFYING  WATER         897 

purify  themselves  through  sedimentation  more  quickly  than  clear 
streams,  owing  to  the  washing  or  scouring  action  of  the  particles  as 
they  fall  through  the  water. 


CHEMICAL  METHODS   OF  PURIFYING  WATER 

Ozone. — Ozone,  discovered  by  Schonbein  in  1840,  is  one  of  the  most 
satisfactory  methods  of  purifying  water  from  a  sanitary  standpoint. 
As  a  germicide  it  is  the  most  effective  of  all  the  methods  used  except 
boiling.  A  well-ozonized  water  is  practically  sterile  and  the  organic 
matter  is  partially  oxidized.  It  is  true  that  a  few  resisting  spores  are 
not  killed,  but  these  are  harmless  when  taken  by  the  mouth.  The  limi- 
tations of  the  ozone  process  are  that  it  does  not  clarify  the  water  in 
any  way,  and  that  it  has  practically  no  effect  upon  the  mineral  salts. 
From  a  practical  standpoint  the  expense  of  producing  ozone  in  suffi- 
cient concentration  is  disproportionately  large,  but  this  is  an  electrical 
engineering  problem  which  is  showing  encouraging  advance. 

As  a  general  rule  it  is  not  desirable  to  add  ozone  to  a  dirty  or  turbid 
raw  water.  It  is  better  first  to  clarify  the  water  by  some  other  method 
before  applying  the  ozone.  The  quantity  of  ozone  required  for  effective 
bacterial  action  depends  upon  the  amount  of  organic  impurities  con- 
tained in  the  water.  Much  of  the  ozone  will  be  used  up  by  these  im- 
purities, and  this  may  happen  so  rapidly  that  it  will  not  have  a  chance 
to  act  upon  the  microorganisms. 

An  impure  water  containing  much  organic  pollution  treated  with 
ozone  may  give  disappointing  results,  from  the  fact  that  unpleasant 
flavors  may  be  developed.  These  are  doubtless  due  to  the  partial  oxida- 
tion of  the  decomposing  organic  matter  with  the  production  of  nitrog- 
enous compounds  not  well  understood. 

For  the  purification  of  water,  ozone  is  produced  by  electrical  dis- 
charges in  the  atmosphere,  and  this  ozonized  air  is  then  brought  into 
intimate  contact  with  the  water.  To  produce  the  ozone  requires  a 
silent  brush  discharge  and  the  air  must  be  cold  and  free  of  moisture. 
If  sparking  occurs  between  terminals,  oxids  of  nitrogen  are  formed 
which  are  corrosive  and  prevent  the  formation  of  ozone.  The  ozonizing 
apparatus  therefore  must  be  carefully  designed,  and  its  operation  needs 
skilled  supervision. 

An  ozonizer  consists  of  two  conducting  metallic  surfaces  separated  by 
a  dielectric,  such  as  glass  or  mica,  and  so  constructed  that  a  current  of 
air  may  pass  between  the  two  conducting  surfaces. 

Figure  113  represents  a  common  form  of  ozonizer.  Oxygen  or  air 
enters  at  A  and  follows  the  course  indicated  by  the  arrows.  The  con- 
ducting surfaces  B  and  C  are  separated  by  a  glass  dielectric  D.  Wires 
30 


898 


THE  runiFicvrioN  ok  wati 


leading  from  an  intluction  coil  arc  connected  with  B  and  C.  As  the 
oxygen  passes  upward  between  the  conducting  surfaces  it  is  subjected 
to  the  influence  of  the  electric  discharge,  and  a  portion  of  the  element  is 
thereby  changed  into  ozone.  The  air  passing  between  the  electrodes  must 
be  dry,  otherwise  peroxid  of  hydrogen  will  form  at  the  expense  of  the 
ozone.  It  is  therefore  customary  to  first  dry  the  air  by  refrigeration 
or  by  passing  it  over  unslaked  lime  before  it  enters  the  ozonizer.  The 
temperature  of  the  air  in  the  ozonizer  must  not  go  above  a  certain 
degree,  else  ozone  will  not  be  formed.  The 
'  maximum  production  of  ozone  takes  place  at 
about  25°  C.  Overheating  may  be  prevented 
by  a  water  jacket  in  contact  with  the  electrodes. 
The  voltage  must  be  high— from  8,000  to  20,000 
volts ;  that  is,  the  current  must  have  a  small  vol- 
ume, but  high  potential.  Ordinarily  only  a  very 
small  percentage  of  the  oxygen  is  transformed 
into  ozone.  Eecently,  however.  Harries  has  ob- 
tained a  yield  of  from  18  to  19  per  cent,  by 
means  of  an  improved  ozonizer. 

The  molecule  of  ozone  (Og)  readily  gives  up 
one  atom  of  this  gas  in  a  nascent  condition.  It 
therefore  has  a  very  strong  oxidizing  action  upon 
organic  matter,  decolorizes  many  pigments,  es- 
pecially of  vegetable  origin,  and  has  a  very  power- 
ful germicidal  action.  In  this  respect  the  action 
of  ozone  corresponds  chemically  to  potassium  per- 
manganate, the  hypochlorites,  and  other  powerful 
oxidizing  chemicals  used  in  water  purification. 

It  is  necessary  to  get  the  ozone  out  of  the 
water  in  order  to  avoid  the  corrosion  of  pipes. 
This  may  be  done  by  aeration,  by  means  of  foun- 
tains or  cascades.  On  account  of  the  insolubility 
of  the  ozone,  it  soon  disappears.  The  fact  that 
ozone  is  largely  insoluble  in  water  makes  it  necessary  to  bring  it  into 
intimate  contact  with  all  portions  of  the  water  to  be  treated.  This  is 
usually  accomplished  by  allowing  the  water  to  trickle  downward  through 
tall  cylinders  filled  with  coke,  lava,  or  other  similar  substances  while 
the  ozone  is  admitted  to  the  bottom  of  the  cylinder.  The  water  flows 
downward,  the  ozonized  air  works  its  way  upward,  and  in  that  way  the 
desired  contact  is  obtained  between  the  ozone  and  every  portion  of  the 
water. 

A  very  small  amount  of  ozone  is  effective  for  the  purification  of 
water.  It  only  requires  from  1  to  3  milligrams  per  liter.  The  modern 
machines   produce   concentrations   as  high  as   10   grams  and   more  of 


Fig.  112. — An  Ozonizer. 
A.  Open  tube  through 
which  air  is  led.  B  and 
C  are  electrodes,  sep- 
arated by  the  glass 
tubes  D,  between  which 
the  current  of  air  pass- 
es. (After  McPherson 
and  Henderson's  "A 
Course  in  General 
Chemistry,"  published 
by  Ginn  and  Co.,  Fig. 
13,  p.  31.) 


CHEMICAL  METHODS  OF  PUEIFYING  WATEE 


899 


ozone  per  cubic  meter  of  air.  The  ozone  not  taken  up  by  the  water 
may  be  used  over  and  over  again.  This  is  accomplished  in  some  of  the 
ozonizing  processes  by  conducting  the  air  that  leaves  the  upper  part  of 
the  water  cylinder  back  to  the  ozonizer. 

In  general^  it  may  be  said  that,  owing  to  the  expense  and  the  elec- 
trical and  engineering  difficulties  involved,  the  ozonizing  process  is 
not  at  present  applicable  to  the  purification  of  water  upon  a  small  scale. 
It  has  been  applied  with  success  upon  a  large  scale  in  a  number  of 
places.  The  first  ozonizing  apparatus  for  the  purification  of  water  on 
a  large  scale  was  installed  by  Siemens-Halske  at  Lille,  France.  Other 
ozonizing  plants  for  purification  of  drinking  water  have  been  installed 


^=^ 


Fig.  113. — An  Installation  for  Treating  Water  with  Ozone. 
A.  Settling  tank.'   B.  Filter.     C.  Storage  reservoir  for  filtered  water.     D.  Tower,  water 
enters  above  and  ozone  below.     E.  Pure  water  reservoir.     F.  Ozonizer.     G.  Dryer,  to 
remove  moisture  from  air  before  it  passes  into  ozonizer.     H.  Fan. 


at  Wiesbaden  and  Paderborn,  in  Germany;  Cosne,  Chartres,  Mce,  Den- 
ard  in  France;  Ginnekin  in  Holland;  Sulina  on  the  Black  Sea,  and 
Petrograd  in  Eussia;  Lindsay,  Ontario;  and  Paris,  in  part,  24,000,000 
gallons  per  day  from  the  Eiver  Marne.  At  Lindsay  the  ozone  treatment 
failed  because  the  ozone  and  the  water  were  not  properly  mingled.  At 
Wiesbaden  much  trouble  was  caused  by  the  oxidation  of  the  iron.  Ex- 
periments at  Ogdensburg,  N.  Y.,  failed  to  remove  the  color  of  the  water. 
Where  water  power  may  be  obtained  for  the  generation  of  the  electricity 
'necessary  to  produce  the  ozone  the  cost  is  very  much  lessened.  The 
principal  systems  at  present  nsed  for  ozonizing  water  are  the  Siemens- 
Halske,  the  Gerhard,  Tindal,  De  Frise,  Otto,  Abraham  Marmier,  Vos- 
maer.  Bridge,  Stynis,  and  others. 

Ozone  treatment  is  best  adapted  to  sewage-polluted  waters,  the  ap- 
pearance of  which  is  satisfactory.  Waters  of  turbid  streams  are  least 
suited  to   this   treatment.      Ozone   must   now   compete   with   bleaching 


900  THE  rUEIFICATION  OF  WATER 

powder,  which  has  nearly  the  same  effect  and  is  cheaper  and  simpler. 
One  objection  to  the  treatment  of  water  by  ozone  is  that  the  electric 
apparatus  is  delicate  and  complicated  and  requires  skilled  attendance. 
The  ozone  processes  are  not  yet  standardized;  at  present  it  is  difficult 
to  determine  what  Avaters  may  best  be  treated  with  it. 

Chlorinated  Lime^ — Bleaching  Powder  or  "Chlorid  of  Lime." — Chlor- 
inated lime,  popularly  miscalled  "chlorid  of  lime,"  and  often  spoken  of 
as  "bleach,"  has  for  years  been  used  to  disinfect  sewage,  outhouses, 
cellars,  and  for  miscellaneous  purposes.  Its  use  in  the  disinfection  of 
water  as  a  practical  process  dates  from  1908,  when  Mr.  G.  A.  Johnson 
was  called  to  solve  the  serious  and  difficult  problem  in  water  purifica- 
tion at  the  Chicago  stock  yards,  the  discharges  from  which  entered 
Bubbly  Creek.  Filtration  of  the  water  of  Bubbly  Creek  was  not  satis- 
factory, and  all  methods  failed  to  abate  the  nuisance  until  Mr.  Johnson 
treated  the  water  with  chlorinated  lime.  The  method  further  attracted 
widespread  attention  by  the  Jersey  City  Water  Company  in  assaying  to 
comply  with  its  contract  to  furnish  pure  water  to  Jersey  City  by  simply 
adding  a  little  bleaching  powder.  Other  municipalities  soon  took  it  up 
in  order  to  render  their  public  water  supply  safe,  until  now  it  is  used  by 
many  cities  and  towns  throughout  the  country. 

Properties. — Chlorinated  lime  is  made  by  saturating  slaked  lime 
with  chlorin  at  ordinary  temperatures.  It  is  a  white  or  whitish  poAvder 
occurring  also  in  friable  lumps;  dry  or  slightly  damp,  with  a  feeble 
odor  of  chlorin  and  a  disagreeable,  bitter,  and  saline  taste.  It  has  an 
alkaline  reaction,  but  finally  bleaches  litmus  paper.  The  medicinal  dose 
administered  by  the  mouth  is  from  one  to  five  grains  (gram,  0.06 — 0.3). 
As  a  mouth  wash  a  one  per  cent,  solution  may  be  used.  The  physiologi- 
cal action  of  chlorinated  lime  resembles  that  of  chlorin  with  the  super- 
added causticity  derived  from  the  lime  in  its  composition.  Externally 
it  is  an  active  irritant  and  sometimes  moderately  caustic. 

A  6  per  cent,  solution  in  water  may  be  made.  However,  all  the  con- 
stituents of  bleaching  powder  are  not  soluble.  Chlorinated  lime  con- 
tains a  large  amount  of  calcium  hydroxid  (Ca(0H)2)  which  is  largely 
insoluble,  hence  the  milky  appearance  of  the  solution,  and  also  the  pre- 
cipitate known  as  "sludge,"  which  settles  rapidly.  The  calcium  oxy- 
chlorid,  and  also  calcium  hypochlorite,  the  active  principles  in  chlor- 
inated lime,  are  readily  soluble  in  water. 

Upon  exposure  to  the  air  the  hypochlorites  deteriorate  rapidly  to 
the  more  stable  and  inert  carbonates.  Great  care  must  therefore  be 
taken  to  keep  the  substance  in  air-tight  containers  and  to  know  the 
correct  amount  of  available  chlorin  in  each  lot  of  the  bleach  at  the  time 
it  is  used. 

Composition. — The  precise  chemical  constitution  of  chlorinated 
lime  is  not  definitely  known,  although  the  matter  has  been  frequently 


CHEMICAL  METHODS  OF  PURIFYING  WATER         901 

investigated.  It  seems  quite  certain  that  neither  cliloride  of  lime,  CaCl^, 
nor  hypochlorite  of  lime,  Ca(0Cl)2,  exist  as  such  in  dry  bleaching 
powder,  but  are  formed  on  dissolving  it  in  water.  Calcium  oxychlorid, 
CaOCla,  is  now  generally  accepted  to  be  the  essential  agent  of  dry  bleach- 
ing powder,  and  calcium  hypochlorite,  Ca(0Cl)2,  to  be  the  active  germi- 
cidal principle  of  the  solution.     Thus: 

CaOCla  '     =  Ca(0Cl)2  +  CaCla 

Calcium  oxychlorid     =     Calcium  hypochlorite     +     Calcium  chlorid. 

Calcium  chlorid  which  is  thus  formed,  or  calcium  carbonate,  which 
forms  when  bleaching  powder  is  exposed  to  carbon  dioxid,  are  both  inert 
so  far  as  germicidal  value  is  concerned. 

When  bleaching  powder  is  added  to  water  it  is  in  no  sense  a  "chlorin" 
treatment.  The  germicidal  action  depends  mainly  upon  the  nascent 
oxygen  which  is  liberated  from  the  hypochlorous  acid. 

The  reactions  which  take  place  are  probably  as  follows : 

2CaOCl2  becomes  in  water  Ca(OCl)o  +  CaCla 
Ca(OCl).  :f  H2CO3  =  CaCOg  +  2H0C1  " 
2H0C1  breaks  down  to  2HC1  +  0, 


Also 


2HC1  +  CaCOa  =  CaCl^  +  HoO  +  CO^ 
CO2  +  H.O  =  "H2CO3" 


While  the  intricate  nature  of  the  chemical  processes  is  somewhat 
involved,  it  is  plain  that  the  active  germicidal  substance  in  the  solution 
is  hypochlorous  acid,  or  its  salt,  calcium  hypochlorite,  both  of  which 
liberate  free  chlorin,  which  in  turn  decomposes  the  water  setting  free 
nascent  oxygen.  Some  nascent  oxygen  is  also  liberated  when  hypochlor- 
ous acid  decomposes : 

2HC10  =  H.O  +  CL  +  0 

The  amount  of  hypochlorites  added  is  usually  expressed  in  terms  of 
"available  chlorin,'-'  although  in  reality  this  represents  the  available 
oxygen  liberated  by  the  chlorin.  Thus  a  good  bleaching  powder  will 
average  35  per  cent,  of  available  chlorin,  which  is  the  equivalent  of 
about  7.9  per  cent,  of  available  oxygen.  By  available  chlorin  is  under- 
stood the  chlorin  readily  liberated  from  its  combination  as  determined 
by  the  usual  thiosulphate  titration. 

How  TO  Dissolve  Chloeinated  Lime.^ — Chlorinated  lime  is  soluble 
in  about  twenty  times  its  weight  of  water,  leaving  an  insoluble  residue 
consisting  mostly  of  calcium  hydroxid,  Ca(0H)2.  Half  a  pound  of 
chlorinated  lime  may  be  dissolved  in  a  gallon  of  water.  Such  a  solu- 
tion contains  approximately  6  per  cent,  by  weight  of  chlorinated  lime, 
representing  about  2  per  cent,  of  available  chlorin. 


903  THE  PURTFTCATTON  OF  WATER 

To  obtain  a  clear  solution  of  chlorinated  lime  it  is  important  to 
remember  that  tlie  available  chlorin  is  readily  soluble,  even  in  fairly  cold 
water,  and  the  undissolved  sludge  of  calcium  hydroxid,  silica,  etc.,  set- 
tles readily.  Settling,  at  least,  takes  place  readily  if  a  few  simple  rules 
are  observed.  (1)  Do  not  mix  too  stiff  a  paste,  otherwise  a  gelatinizing 
action  takes  place  and  greater  difficulty  in  settling  is  encountered.  (2) 
Never  mix  a  paste  with  less  than  one-half  a  gallon  of  water  for  one 
pound  of  chlorinated  lime.  (3)  It  is  not  necessary  or  desirable  to 
grind  up  or  break  up  the  lumps  too  thoroughly;  the  available  chlorin 
nearly  all  dissolves  readily,  and  too  much  agitation  is  detrimental  to 
prompt  settling.  With  these  points  in  view  a  stock  solution  containing 
approximately  2  per  cent,  of  available  chlorin  may  be  made  as  follows : 

Three  hundred  pounds  commercial  chlorinated  lime  (35  per  cent, 
available  chlorin)  =105  pounds  of  available  chlorin,  assuming  a  recov- 
ery of  100  pounds  of  this  free  from  sludge.  These  100  pounds  must  be 
contained  in  600  gallons  to  give  a  clear  2  per  cent,  solution.  Due  allow- 
ance must  be  made  for  proper  washing  of  the  sludge,  for  it  contains,  in 
addition  to  the  suspended  lime  and  silica,  a  solution  of  equal  strength  to 
that  of  the  clear  liquid.  The  amount  of  sludge  is  equivalent  to  about 
one  gallon  for  each  five  pounds  of  chlorinated  lime  used. 

Method  of  Dosing. — While  the  chlorinated  lime  treatment  of  wa- 
ter supplies  is  essentially  simple,  yet  it  requires  able  professional  super- 
vision; disappointing  results  will  come  from  haphazard  work.  The 
great  essential  is  a  uniform  dosing  of  a  standard  solution. 

Economical  working  makes  it  desirable  to  use  two  tanks,  each 
equipped  with  agitators  and  a  looped  chain  as  a  drag  along  the  bottom. 
These  tanks  should  be  made  of  concrete,  or  at  least  lined  with  cement, 
and  adjustable  means  provided  for  drawing  otf  the  clear  liquor  from 
above,  as  well  as  an  outlet  for  removing  the  sludge  at  the  bottom. 

Assuming  that  two  700-gallon  tanks  are  provided,  and  that  300 
pounds  of  chlorinated  lime  giving  600  gallons  of  clear  2  per  cent,  solu- 
tion are  to  be  prepared  in  each  tank  at  one  mixing,  the  procedure  should 
be  as  follows : 

Into  tank  No.  1,  Avhich  is  empty,  is  drawn  200  gallons  of  weak 
wash  water  from  tank  No.  2. 

Then  300  pounds  of  chlorinated  lime  is  dumped  into  the  tank  and 
mixed  for  one-half  hour. 

The  tank  is  now  filled  to  a  mark  indicating  660  gallons  with  the 
remaining  wash  water  from  tank  No.  2,  which  does  not  have  to  be 
particularly  clear. 

This  is  now  allowed  to  settle  for  at  least  8  hours  and  preferably 
over  night,  when  600  gallons  of  clear  solution  will  be  ready  to  draw 
off  to  the  stock  tank.  There  will  remain  about  60  gallons  of  sludge  which 
requires  washing  to  obtain  the  remaining  available  chlorin.     The  agi- 


CHEMICAL  METHODS  OF  PURIFYING  WATER 


903 


tator  is  now  started  in  tank  No.  1,  which  is  filled  to  the  660-gallon  mark 
with  water,  and  then  allowed  to  settle.  This  wash  water  is  used  in 
making  up  the  next  batch  in  No.  2  tank;  the  now  practically  exhausted 
lime  sludge  in  tank  No.  1  is  thrown  away. 

The  standard  stock  solution  thus  prepared  will  contain  available 
chlorin  equal  to  %  pound  of  chlorinated  lime  per  gallon,  or  about  2 
per  cent,  available  chlorin,  or  6  per  cent,  of  chlorinated  lime  by  weight. 
Hence  an  average  clear  water  requiring  8  pounds  of  chlorinated  lime 
per  million  gallons  will  require  16  gallons  of  this  standard  solution  per 
million  gallons  of  water.  This  is  a  trifle  less  than  1  drop  of  this  solu- 
tion containing  2  per  cent,  of  available  chlorin  in  a  gallon  of  water. 

The  following  table  covers  the  range  of  chlorinated  lime  ordinarily 
used  in  water  purification,  and  may  be  found  useful  for  comparison : 


Pounds  Chlorinated 
lime   per   1,000,000 
Gallons    of    Water 

Parts     Chlorinated 
Lime  per  1,000,000 
Parts  Water 

Parts    Chlorin    per 
1,000,000  Parts  Wa- 
ter 

Grains  Chlorinated 
lime     per     Gallon 
of  Water 

Grains       Available 
Chlorin  per  Gallon 
of  Water 

Drops    Chlorinated 
Lime     Solution     2 
Per  Cent.    Chlorin 
or  J4  Pound  Chlor- 
inated   liime     (per 
Gallon)     Used    per 
Gallon  Water 

2 

.24 

.48 
.72 
.96 
1.20 
1.44 
1.68 
1.92 
2.16 
2.40 
2.64 
2.88 
3.12 
3.36 
3.60 

.08 
.16 

.24 

.32 

.40 

.48 

.56 

.64 

.72 

.80 

.88 

.96 

1.04 

1.12 

1.20 

.014 
.028 
.042 
.056 
.070 
.084 
.098 
.112 
.126 
.140 
.154 
.168 
.182 
.196 
.210 

.005 
.009 
.014 
.019 
.023 
.028 
.033 
.037 
.042 
.047 
.051 
.056 
.061 
.065 
.070 

.25 

4 

.50 

6 

.75 

8 

1.00 

10. . 

1.25 

12 

1.50 

14 

16 

1.75 
2.00 

18 

20 

2.25 
2.50 

22 

24 

2.75 
3.00 

26 

3.25 

28 

3.50 

30 

3.75 

Amount  Used  in  Water  Purification. — The  remarkable  germi- 
cidal power  of  chlorinated  lime  is  better  understood  when  it  is  known 
that  3  grains  of  a  practically  harmless  substance  will  kill  myriads  of  bac- 
teria contained  in  a  barrel  of  water.  Ordinarily  the  amounts  used  are 
from  1  to  2,  or  5  parts  in  terms  of  "available  chlorin"  per  million  gal- 
lons of  water.  In  practice  the  actual  amount  used  in  water  purification 
is  from  5  to  12  or  more  pounds  of  bleaching  powder  per  million  gallons 
of  water.  The  bleach  cannot  be  detected  by  the  sense  of  taste  provided 
the  amount  does  not  exceed  25  pounds. 

The  amount  of  chlorinated  lime  necessary  to  add  to  a  water  in  order 
to  accomplish  satisfactory  results  varies  with  the  composition  of  the 
water.     In  general,  the  more  organic  matter  the  water   contains  the 


904  THE  PUEIFICATION  OF  WATEK 

more  bleaching  powder  is  necessary.  This  is  for  the  reason  that  some 
of  the  bleaching  powder  is  nsed  to  oxidize  the  organic  matter  before  it 
can  reach  its  germicidal  action.  A  bacterial  reduction  of  99  per  cent, 
may  be  obtained  in  a  water  containing  little  organic  matter  with  1  part 
per  million,  whereas  it  requires  1  part  to  25,000  parts  in  sewage  to 
affect  a  similar  bacterial  reduction. 

New  York  uses  16  pounds  per  million  gallons;  Omaha  TiA  pounds 
per  million  gallons  after  coagulation  and  sedimentation;  Cincinnati, 
5  to  121/^  pounds;  Toronto,  6  pounds;  Montreal,  5  to  7^  pounds;  Cleve- 
land, 16  pounds;  Erie,  7  to  10  pounds;  Milwaukee,  6  pounds;  Pitts- 
burgh, 3  pounds  after  slow  sand  filtration;  Jersey  City,  5  to  8  pounds; 
Council  Bluffs,  15  pounds  following  the  alum  precipitation;  Nashville, 
14  pounds.  Bleaching  powder  is  also  used  to  purify  the  public  water 
supplies  of  St.  Louis,  Minneapolis,  Chicago,  Brainerd,  Minn.;  Eidg- 
wood,  N.  J. ;  Coming,  N".  Y. ;  Grand  Bapids,  Mich. ;  Little  Falls,  N.  J. ; 
Harrisburgh,  Pa.;  Baltimore,  Md. ;  Niagara  Falls;  Toronto;  Ottumwa, 
la.,  and  other  places. 

Clark  and  Gage  found  that  0.1  part  of  available  chlorin  per  100,000 
effected  a  satisfactory  purification  of  the  Merrimac  Eiver  water ;  that  is, 
results  were  obtained  equal  to  slow  sand  filtration.  B.  coli  was  entirely 
eliminated.  They  discovered  the  interesting  fact  that  the  hypochlorite 
is  a  differential  germicide,  that  it  destroys  some  bacteria  more  readily 
than  others.  When  small  quantities  are  employed  certain  species 
growing  at  body  temperature  are  only  slightly  affected.  In  Pittsburgh 
it  was  found  that  0.13  part  of  chlorinated  lime,  measured  in  terms  of 
available  chlorin  per  1,000,000  parts  of  water,  was  sufficient  to  prac- 
tically sterilize  the  Allegheny  Eiver  water  after  it  had  passed  the  sand 
filters.  It  required  as  much  as  1  part  per  1,000,000  to  accomplish  the 
same  results  in  the  raw  water.  In  Minneapolis  from  2  to  4  parts  per 
1,000,000  have  been  used.  In  the  Jersey  City  case,  already  referred  to, 
5  pounds  of  bleaching  powder,  containing  35  per  cent,  of  available 
chlorin,  are  added  to  each  million  gallons  of  water  treated.  The  raw 
water  in  this  case  is  not  highly  polluted,  ranging  as  low  as  30  bacteria 
per  cubic  centimeter,  and  rarely  going  over  15,000.  The  number  of 
bacteria  in  the  treated  water  averages  only  15  bacteria  per  cubic  centi- 
meter, and  B.  coli  is  practically  absent.  It  was  found  only  once  out 
of  455  samples. 

Summary. — The  purification  of  water  by  means  of  a  little  bleaching 
powder  is  cheap,  reliable,  efficient,  harmless,  and  easy  of  application, 
all  which  make  it  an  attractive  method.  When  added  in  proper  quan- 
tities it  leaves  no  undesirable  chemical  substance  in  the  water.  It  must, 
however,  be  remembered  that  bleaching  powder  in  no  sense  clarifies  a 
water.  In  fact,  turbidity  interferes  with  its  action  to  a  certain  extent. 
It  cannot,  therefore,  render  a  turbid  supply  entirely  satisfactory.     Fur- 


CHEMICAL  METHODS  OF  PUEIFYING  WATEE         905 

thermore,  while  chlorinated  lime  in  such  small  quantities  will  kill 
bacteria  it  will  not  purify  organic  matter  nor  cure  discoloration,  nor 
take  away  the  unpleasant  smells  which  raw  waters  often  contain. 

Chlorinated  lime  has  a  slight  tendency  to  add  to  the  hardness,  while 
chlorinated  soda  renders  the  water  correspondingly  soft.  The  latter, 
however,  is  more  expensive  than  the  former. 

Impure  waters  containing  organic  matter  of  any  kind  may,  when 
attacked  by  hypochlorites,  give  rise  to  unpleasant  flavors.  These  sub- 
stances appear  related  to  the  amins,  chloramins,  and  other  compounds 
the  exact  composition  of  which  requires  further  study.  Hence  the 
chemical  sterilization  of  impure  waters  without  subjecting  them  to  some 
preliminary  treatment  may  give  disappointing  results. 

Bleaching  powder  is  also  used  in  the  disinfection  of  the  water  of 
swimming  pools,  for  street  sprinkling,  and  flushing,  for  the  disinfec- 
tion of  feces  and  sputum;  and  to  a  certain  extent,  for  the  disinfection 
of  glassware,  fabrics,  brushes,  and  combs.  It  is  one  of  the  best  sub- 
stances we  have  for  the  general  disinfection  of  rough  places,  such  as 
slaughter-houses,  bakehouses,  dairies,  outhouses,  cellars,  and  the  like. 
In  surgery  chlorinated  soda  is  used,  the  action  of  which  is  entirely 
analogous  to  chlorinated  lime. 

The  hypochlorite  treatment  is  also  suitable  for  water  on  a  small 
scale,  as  for  military  use,  camps,  tourists,  explorers,  and  others.  For 
tourists  and  campers  a  solution  may  be  prepared  by  adding  one-half  a 
teaspoonful  of  chlorinated  lime  to  one  pint  of  water.  Use  one  teaspoon- 
ful  of  this  to  10  gallons;  36  drops  to  1  gallon;  or  9  drops  to  1  quart. 
Let  stand  at  least  15  minutes. 

Chlorln. — Liquid  chlorin  may  be  used  in  place  of  chlorinated  lime. 
^\It  is  just  as  efficient  and  acts  in  practically  the  same  manner.  Liquid 
chlorin  may  be  obtained  on  the  market  in  small  cylinders  as  a  practic- 
ally pure  chemical  substance;  it  does  not  deteriorate.  One  pound  of 
liquid  chlorin  is  about  equal  in  sterilization  value  to  8  pounds  of  "chlorid 
of  lime."  Water  treated  with  liquid  chlorin  is  less  liable  to  taste  or  odor, 
due  perhaps  to  the  more  accurate  control  possible ;  the  apparatus  is  more 
compact  and  therefore  more  suitable  for  a  traveling  or  emergency  plant. 
Liquid  chlorin  is  applicable  under  all  conditions  and  all  pressures  and 
is  therefore  adapted  to  remote  control,  especially  as  the  amount  of  gas 
may  be  controlled  by  an  automatic  feed.  The  difficulty  of  freezing  in 
the  winter  time,  encountered  in  the  use  of  chlorid  of  lime,  does  not  take 
place  with  liquid  chlorin.  The  cost  of  the  chemicals  is  about  the  same, 
but  the  cost  of  installation  and  operation  is  in  favor  of  liquid  chlorin. 

There  are  two  general  types  of  apparatus,  one  by  which  the  chlorin 
gas  is  introduced  directly  into  the  water  or  sewage,  and  the  other  by 
which  the  chlorin  gas  is  first  dissolved  in  a  small  quantity  of  water,  and 
the  resulting  chlorin  solution  piped  to  the  point  of  application.    The  first 


90G  '\1U<:  "PF17IFT0ATTOX  OF  WMM-Ml 

type  is  called  a  dry  feed  and  the  second  type  a  wet  feed.  The  quanti- 
ties added  are  usually  expressed  in  ])arts  of  chlorin  per  million  parts  of 
water  by  weight;  8.3  pounds  of  chlorin  to  1,000,000  gallons  of  water  is 
the  equivalent  of  one  part  per  million,  since  a  gallon  of  water  weighs  8.3 
pounds.  The  amounts  used  to  disinfect  the  water  are  the  same  as  stated 
under  chlorinated  lime. 

Chlorin  is  used  to  disinfect  the  water  supply  of  Buffalo,  New  York, 
New  Haven  and  Stamford,  Conn.;  New  Brunswick,  New  Jersey  and 
other  places. 

Permanganate  of  Potash. — Permanganate  of  potash  was  much  used 
in  India,  particularly  in  wells  during  cholera  epidemics;  also  in  water 
tanks  on  board  ships,  and  other  places.  Enough  permanganate  is  added 
to  secure  a  faint  pink  tinge,  which  indicates  a  slight  excess.  The  per- 
manganate acts  as  an  oxidizing  agent  precisely  as  ozone,  or  similar  to 
the  hypochlorites.  It  is  a  powerful  germicide,  but  not  sufficiently  so 
in  the  strength  used  to  depend  upon  it.  If  too  much  is  added  to  wells, 
springs,  etc.,  so  as  to  kill  the  fish,  frogs,  and  turtles,  the  water  may 
be  spoiled  by  putrefaction  of  their  dead  bodies.  Like  all  chemical  meth- 
ods, the  action  is  not  continuous;  the  agent  expends  itself  in  oxidizing 
organic  matters  before  attacking  the  bacteria,  and  the  amount  necessary 
for  the  purification  of  a  water  depends,  therefore,  upon  its  character. 

Experiments  by  Clark  and  Gage  show  that  complete  sterilization 
is  not  obtained  by  the  use  of  permanganate  of  potash.  Over  98  per 
cent,  of  the  bacteria  were  eliminated  by  treating  water  with  0.5  part 
to  100,000  in  from  4  to  6  hours.  Larger  amounts  of  potassium  per- 
manganate or  longer  times  gave  no  better  results.  The  cost  of-  the 
treatment  when  using  5  parts  per  1,000,000  is  from  $3  to  $4  per  mil- 
lion gallons.  We  therefore  see  that  potassium  permanganate  has  a 
comparatively  low  efficiency  with  a  relatively  high  cost,  which  will  always 
limit  its  usefulness.  Further,  the  method  is  difficult  of  practical  appli- 
cation, being  rather  slow.  Occasionally  it  may  be  serviceable  on  ships, 
in  the  field,  in  an  army  encampment,  or  an  isolated  well. 

Alum  or  Sulphate  of  Aluminium. — The  single  and  double  sulphates 
of  aluminium  have  long  been  used  to  clarify  turbid  waters.  In  the 
amounts  used  they  have  no  direct  germicidal  action,  nor  any  direct 
chemical  action  upon  the  water  itself.  The  action  is  entirely  an  in- 
direct one,  and  depends  upon  the  fact  that  the  alkaline  carbonates  react 
upon  the  alum  to  form  aluminium  hydrate.  This  salt  has  a  large  col- 
loidal molecule  and,  being  insoluble,  is  thrown  out  of  solution  as  a 
flocculant  precipitate  which  entangles  much  of  the  suspended  matter 
and  bacteria.  In  a  sense  the  purification  of  water  with  alum  corre- 
sponds very  much  to  the  clearing  of  coffee  with  the  white  of  egg.  Some 
of  the  aluminium  hydrate  may  also  combine  directly  with  the  organic 
matter  to  form  undetermined  compounds.     The  reaction  is  as  follows: 


CHEMICAL  METHODS  OF  PUEIFYING  WATEE         907 

ALCSOOa.lSH^O  +  SCaCOs  +  SH^O  =  SCaSO^  +  2A1(0H)3  +  SCO. 
666.7  +3X100  +  3X18  =  3X136+     2X78    +"3  X  44 

1  grain  of  alum  per  gallon  =  142     lbs.  per  million  gallons. 
1       "       "        "        "         "       =     17.1  parts  per  million  parts  of  water. 

1^-1  X    -.- -  ^  =  7.7  parts  per  million  of  aUtalinity  expressed  as  CaCOa. 

DD0.7 

142:100::7.7:x  =  5.5. 

100  lbs.  of  alum  per  million  gallons  =  5.5  parts  per  million  of  alkalinity 

as  CaCOs. 

In  water,  however,  the  reaction  is  with  calcium  bicarbonate : 

Al2(S04)3.18H20  +  3Ca(HC03)2=3CaS04+2Al(OH)3  +  6CO2 

666.7  +      3X262    =3X136+2X156     +6X44 

Therefore  1  grain  of  alum  per  gallon  liberates  6.8  parts  per  million  CO2. 

And  1  grain  of  alum  per  gallon  converts  7.7  parts  per  million  bicarbonate 

alkalinity  to  7.7  parts  sulphates  or  incrustants. 

Reactions  using  soda  ash  with  alum : 

Al2(S04)3 .  I8H2O  +  SNasCOs  +  3H2O  =3Na2S04  +  2A1(0H)3  +  3CO2 

666.7  3X106  =3X142         2  X  78    3  X  44 

318 
1  grain  per  gallon  alum  requires  of  17.1  =  8.2  p.  p.  m. 

Na2C03  =  68  lbs.  per  m.  g.  Na.COs 

132 
1  grain  per  gallon  alum  liberates    _  _ ,  ^    of  17.1  =  3.4  p.  p.  m.  CO2. 

OOD.  / 

Since  1  grain  per  gallon  alum  =  8.2  p.  p.  m.  Na2C03  and  7.7  p.  p.  m. 
of  alkalinity,  and  1  p.  p.  m.  =  8.3  lbs.  p   m.  g.,  then  1  p.  p.  m.  alkalinity  as 

Na2C03  =  |y  X  8.3  =  8.8  lbs.-  per  m.  g. 

Reaction  using  lime  with  alum : 

Al2(S04)3.  I8H2O  +  3Ca(OH)2  =3CaS04  +2A1(0H)3 

666.7  168CaO 

168 
1  grain  per  gallon  alum  requires  ^-  of  17.1  =  4.3  p.  p.  m.  CaO  = 

36  lbs.  per  m.  g.  CaO. 
This  liberates  no  CO2. 
1  grain  per  gallon  alum  with  lime  increases  hardness  7.7  p.  p.  m. 

It  will  be  seen  that  if  alum  is  added  in  just  sufficient  quantities 
to  a  water  it  leaves  no  undesirable  constituent  in  the  water.  This  is 
important,  for  there  is  a  great  prejudice  against  the  addition  of  a  chemi- 
cal, especially  alum,  to  drinking  water.  In  Washington  it  is  actually 
forbidden  by  law,  despite  the  fact  that  it  has  been  shown  that  in  times 
of  great  turbidity  the  only  known  method  of  clearing  the  Potomac  water 
is  by  the  use  of  a  coagulant  such  as  alum.  It  has  already  been  pointed 
out  that  there  are  many  such  turbid  waters  in  our  country  which  contain 
silt  in  such  fine  subdivision  that  even  prolonged  sedimentation  and  re- 
peated filtration  will  not  render  them  entirely  clear. 

In  the  use  of  alum  good  results  depend  upon  adding  it  in  just  the 


908  THE  PURIFICATION  OF  WATER 

right  amount.  The  quantity  will  vary  with  the  turbidity  and  the  amount 
of  calcium  carbonate  contained  in  the  water.  The  usual  amount  of  alum 
added  to  water  is  from  1  to  4  grains  per  gallon.  This  should  be  care- 
fully determined  from  time  to  time,  for  if  not  enough  alum  is  added  the 
result  is  incomplete,  and  if  too  much  is  added  it  remains  in  the  water 
as  such.  The  process  therefore  needs  constant  supervision,  for  turbid 
waters  usually  come  from  turbulent  streams,  which  are  subject  to  sudden 
variations.  If  the  process  is  left  to  automatic  devices  or  placed  in  in- 
competent hands  it  is  sure  to  give  disappointing  results. 

Few  waters  may  be  satisfactorily  purified  by  the  use  of  alum  alone. 
The  alum  should  be  regarded  only  as  one  part  of  the  process.  Subse- 
quent sedimentation,  filtration,  or  hypochlorite,  etc.,  are  necessary,  de- 
pending upon  circumstances.  Alum  alone  should  never  be  depended 
upon  to  purify  a  sewage-polluted  water.  When  properly  combined 
with  filtration  it  will  eliminate  a  large  percentage  of  the  bacteria.  (See 
also  Mechanical  Filtration,  page  890.) 

Sulphate  of  iron  and  lime  in  combination  are  used  in  many  places. 
At  St.  Louis  it  was  introduced  as  an  emergency  installation  to  clarify 
the  muddy  waters  of  the  Mississippi,  to  make  a  good  impression  during 
the  Louisiana  Purchase  Exposition  in  1904.  It  gave  such  satisfactory 
results  that  it  was  decided  to  continue  its  use. 

Reaction  using  lime  and  iron  (ferrous  sulphate): 

FeS04.7H20  +  Ca(HC03)2  =  Fe(HC03)2  +  CaSO^  +  TH^O 
278  lOOCaCOs  178  136 

Fe(HC03)2  +  2Ca(OH)2  =  Fe(0H)2"-|-  2CaC03  +  2H2O 
178  112CaO  89.9  2X100 

2Fe(OH)2  4-  O  -f-  H2O  =2Fe(OH)2 
2X89.9     16       18      2X106.9 

1  grain  per  gallon  FeSO..  7H2O  =  lY.l  X  ^-  =  6.2  p.  p.  m.  alkalinity 

278 

and  100  lbs.  per  m.  g.  ^  4.5  p.  p.  m.  alkalinity. 

1  grain  per  gallon  FeSOi  converts  6.2  p.  p.  m.  alkalinity  to  6.2  p.  p.  m. 

incrustants. 

112 
To  precipitate  the  ferrous  bicarbonate  first  formed  requires  17.1  X   „^q- 

=  6.9  p.  p.  m.  CaO  ^  57  lbs.  per  m.  g.  for  each  grain  per  gallon  FeS04. 

The  dissolved  oxygen  in  the  water  completes  the  reaction,  forming  brown 
re(0H)3. 

Lime  and  iron  are  cheaper  than  sulphate  of  aluminium.  Their 
application  is  much  more  difficult  to  control  adequately,  and  it  should 
never  be  undertaken  except  with  the  assistance  of  a  competent  resident 
chemist  and  good  appliances  for  adding  the  lime  in  any  quantity  that 
may  be  required  by  the  composition  of  the  water.     At  St.  Louis  the 


CHEMICAL  METHODS  OE  PUEIFYING  WATEE         909 

water  is  subject  to  the  iron  and  lime  treatment/  followed  by  subsidence 
in  large  basins  in  which  the  bulk  of  the  precipitate  settles.  This  par- 
tially purified  water  is  then  sent  to  the  city  without  filtration. 

Metallic  Iron:  the  Anderson  Process. — The  Anderson  process  (pat- 
ented) for  the  purification  of  water  consists  in  agitating  the  water  in 
contact  with  metallic  iron  a  portion  of  which  is  taken  into  solution  as 
ferrous  carbonate.  This  action  is  brought  about  by  the  CO2  in  the  water 
which  attacks  the  iron.  Upon  subsequent  aeration  the  ferrous  car- 
bonate is  oxidized  and  precipitated  out  as  the  insoluble  ferric  hydrate, 
which  accomplishes  all  the  good  and  none  of  the  bad  effects  which  fol- 
low the  use  of  alum.  The  precipitate  is  partially  removed  by  sedi- 
mentation, or  filtration  may  complete  the  process.  The  process  is  used 
on  a  large  scale  at  Antwerp,  Belgium,  where  the  water  passes  through 
long  revolving  cylinders  containing  baffle  plates  and  loose  pieces  of 
metallic  iron.  As  the  cylinders  revolve  the  iron  is  continually  carried 
up  and  dropped  through  the  water  in  a  constant  shower.  The  water 
passes  slowly  from  one  end  of  the  cylinder  to  the  other. 

The  process  theoretically  is  an  excellent  one,  but  apparently  enough 
iron  is  not  always  obtained  in  solution  to  accomplish  the  results  when 
applied  on  a  large  scale.  Especially  when  peaty  waters  are  used,  it  seems 
impossible  to  get  enough  iron  into  solution  in  the  time  which  can  be 
allowed;  or  the  inorganic  acids  may  form  soluble  compounds  with  the 
iron,  thus  defeating  the  object  of  the  process.  Other  places  where 
the  Anderson  process  is  used  are  Dortrecht,  Holland,  Boulogne-sur- Seine, 
near  Paris,  and  elsewhere. 

Copper  Sulphate. — The  use  of  copper  sulphate  in  drinking  waters  was 
proposed  by  George  T.  Moore  of  the  United  States  Department  of  Agri- 
culture in  1904.  The  original  claim  was  that  copper  sulphate  in  mi- 
nute amounts  would  poison  algae  which  produced  objectionable  tastes 
and  odors,  and  the  further  claim  was  made  that  it  was  also  capable 
of  destroying  typhoid  and  other  pathogenic  microorganisms.  We  know 
now  that  copper  sulphate  in  great  dilution  is  a  specific  poison  for  many 
algae  and  other  microscopic  organisms,  but  that  it  has  little  or  no 
effect  upon  typhoid,  cholera,  or  dysentery  .bacilli  in  the  amounts  used. 

Copper  sulphate  is  used  in  the  proportion  of  0.1  to  0.25  part  per 
1,000,000  parts  of  water.  Some  algae  require  larger  doses.  Most  of 
the  copper  combines- with  the  bodies  of  the  microorganisms  and  settles 
with  them  to  the  bottom  and  in  this  way  is  removed  from  the  water. 
If  the  water  is  afterwards  filtered  most  of  the  remaining  copper  is  re- 
moved. The  copper  remaining  in  the  water  is  in  such  minute  amounts 
that  there  seems  to  be  no  real  danger  in  using  it  in  this  way  or  even 
in  its  occasional  use  in  somewliat  larger  doses  where  the  water  is  very 
bad. 

^2.13  grains  of  iron  sulphate  per  gallon  and  7.39  grains  of  lime  per  gallon. 


910  '        THE  PURIFICATION  OF  WA^rFR 

The  method  of  applying  the  eoppcr  is  to  place  weighed  fjnantities 
of  the  copper  sulphate  in  loose  cloth  bags  and  to  tow  them  back  and 
forth  with  rowboats  through  the  water  of  the  reservoir  until  the  material 
is  dissolved.  It  should  be  remembered  that,  while  the  copper  kills 
some  species  of  organisms  in  the  amounts  used,  it  has  no  effect  what- 
ever upon  others.  In  fact,  it  permits  the  growth  of  certain  species  hy 
removing  the  retarding  symbiants,  thus  clearing  the  way  for  stronger 
groAvths  of  the  forms  that  are  not  directly  affected.  Copper  sulphate 
may  therefore  entirely  change  the  flora  in  a  reservoir.  This  change 
is  frequently  accompanied  by  a  great  improvement  in  odors  and  tastes. 
On  the  other  hand,  the  destruction  or  suppression'  of  one  species  may 
be  followed  by  an  overgrowth  of  an  equally  objectionable  and  more 
hardy  form.  Therefore  the  results  from  the  use  of  copper  sulphate 
for  the  correction  of  odors  and  tastes  in  water  vary  from  complete  suc- 
cesses to  utter  failure. 

It  is  clearly  established  that  copper  sulphate  does  not  prevent  or 
even  materially  reduce  putrefaction  and  the  tastes  and  odors  resulting 
from  it.  According  to  Hazen,  the  method  of  treating  water  with 
copper  sulphate  is  easily  and  quickly  applied,  and  considerable  good 
has  come  from  it.  The  correction  is  only  partial,  however,  and  is  not 
always  permanent.    It  is  not  therefore  to  be  relied  upon  in  all  cases. 


ULTRAVIOLET   RAYS  ^ 

Eecently  the  well-known  germicidal  power  of  the  ultraviolet  rays 
has  been  put  to  practical  use  in  the  sterilization  of  water,  milk,  and 
other  substances.  These  rays,  of  short  wave  length,  may  be  obtained 
from  the  Cooper-Hewitt  mercury  vapor  lamp,  which  is  very  rich  in 
ultraviolet  rays.  Nagier  conceived  the  idea  that  this  lamp  might  be 
used  for  the  sterilization  of  water,  and  the  experiments  made  in  France, 
England,  and  elsewhere  show  this  assumption  to  be  correct.  As  glass 
is  opaque  to  ultraviolet  rays,  it  is  necessary  to  use  quartz  or  lamps 
made  of  fused  silica.  The  apparatus  used  in  the  experiments  ^  of  Thresh 
and  Bealle  consists  of  an  aluminium  cylinder  about  12  inches  long  by  6 
inches  in  diameter  containing  a  Cooper  Hewitt  quartz  lamp  with  an  in- 
ternal diaphragm,  which  causes  the  water  entering  at  one  end  to  travel 
along  the  cylinder  in  close  proximity  to  the  lamp.  By  an  ingenious  ar- 
rangement the  moment  the  light  goes  out  the  flow  of  water  is  stopped. 
This  small  apparatus  is  capable  of  sterilizing  50  to  200  gallons  of  water 
per  hour,  depending  upon  the  character  of  the  water.  In  clear  water 
many  of  the  bacteria  are  killed  in  from  5  to  20  seconds.     The  resisting 

^See  also  page  1119. 
'Lancet,  Dec.  24,  1910. 


ULTKAVIOLET  EAYS  911 

spores  succumb  in  30  to  60  seconds,  B.  coll  in  15  to  20  seconds,  B. 
typhosus  10  to  20  seconds,  cholera  vibrio  10  to  15  seconds.  The  pres- 
ence of  colloidal  material  or  turbidity  retards  the  actions  of  the  rays. 
The  current  used  in  these  experiments  was  6  amperes  and  130  volts. 
The  results  show  that  a  fairly  clear  and  bright  Avater  may  be  practically 
sterilized  by  exposure  to  ultraviolet  rays  for  a  brief  time.  The  sim- 
plicity of  the  apparatus  and  its  comparative  cheapness  make  it  attractive, 
so  that  it  doubtless  will  receive  much  attention  in  the  future. 

Marseilles  recently  adopted  the  ultraviolet  rays  to  purify  its  water 
supply.  There  are  preliminary  roughing  filters,  and  the  water  passes 
the  quartz  tube  mercury  arc  lamp  three  times.  No  B.  coli  were  found 
in  the  treated  water,  and  the  total  bacterial  reduction  was  98.3  per  cent. 
It  is  probable  that  the  bacteria  are  killed  by  exposure  to  the  direct 
action  of  the  ultraviolet  rays  themselves.  The  process  does  not  in  any 
way  clarify  the  water. 

Other  electrical  methods  have  from  time  to  time  been  devised  for 
the  purification  of  water,  using  the  water  itself  as  an  electrolyte.  These 
processes  have  not  yet  been  developed  to  give  successful  results  on  a 
large  scale,  but  much  may  be  hoped  from  them,  and  they  are  worth 
careful  study. 


CHAPTER  VI 
WATER  AND  ITS  RELATION  TO  DISEASE 

Water  is  a  vehicle  for  certain  infections  such  as  cholera,  typhoid 
fever,  dysentery,  and  other  diseases,  having  their  primary  seat  in  the 
digestive  tract.  It  may  carry  inorganic  poisons  such  as  lead.  It  is 
responsible  for  a  large  group  of  nutritional  and  dietetic  disorders  less 
well  understood.  It  may  contain  qualities  which  bring  about  derange- 
ments of  metabolism  resulting  in  such  conditions  as  goiter;  further,  it 
may  be  the  medium  for  carrying  infections  now  not  generally  regarded 
as  water-borne,  or  it  may  lower  resistance  so  as  to  favor  infections  not 
water-borne.  It  is  also  occasionally  responsible  for  conveying  animal 
parasites,  amebae,  worms,  etc. 

While  water  has  an  established  place  among  the  carriers  of  certain 
infections,  it  has  not  a  supreme  or  exclusive  place,  and  this  should  be 
kept  carefully  before  us.  The  tendency  to  exaggerate  the  importance 
of  water  as  a  bearer  of  disease  and  death  has  sometimes  led  to  over- 
statement. The  facts  are  bad  enough  and  do  not  require  extravagant 
language  to  emphasize  their  importance.  The  greatest  danger  in  water 
is  pollution  from  human  sources.  All  the  discharges  from  the  body: 
urine,  feces,  expectoration,  secretions  from  the  nose,  and  washings  from 
the  skin,  find  their  way  sooner  or  later  into  our  streams,  especially 
where  modern  water-carriage  systems  are  installed  for  the  disposal  of 
wastes.  All  sewage-polluted  water  must  be  regarded  as  dangerous, 
whether  there  are  any  known  cases  of  typhoid  fever  on  the  water- 
shed or  not.  It  is  highly  probable  that  the  sewage  of  large  communities 
always  contains  typhoid  bacilli  in  larger  or  smaller  numbers,  because 
in  large  communities  typhoid  fever  does  not  die  out  completely  at  any 
time,  and  carriers  and  missed  cases  are  growing  in  interest  and  im- 
portance. 

Water  differs  in  several  essential  particulars  from  any  other  article  of 
diet.  Above  all,  it  is  partaken  of  raw,  while  perhaps  90  per  cent,  of  all 
our  other  food  is  disinfected  by  cooking  before  it  is  used.  Again,  it 
is  a  vehicle  which  comes  in  contact  with  many  objects  spread  over  broad 
acres,  and  it  is  the  natural  vehicle  for  the  removal  of  wastes  from  these 
areas.    Its  great  solvent  and  erosive  powers  favor  this  action. 

The  relation  of  water  supply  to  sickness  and  death  has  been  shown 
with  force  in  many  cities,  notably  at  Lowell  and  Lawrence,  Mass. ;  in 
Albany,  N.  Y. ;  at  Jersey  City  and  Newark,  N.  J.;  at  Philadelphia  and 

912 


THE  MILLS-EEINCKE  PHENOMENON  913 

Pittsburgh,  Pa.;  at  Chicago,  111.;  and  abroad  at  London,  Paris,  Ham- 
burg, Altona,  Berlin,  and  many  other  cities. 


THE   MILLS-REINCKE   PHENOMENON 

Following  the  filtration  of  the  water  supply  of  Lawrence,  Mass.,  in 
September,  1893,  Mr.  Hiram  F.  Mills,  a  member  of  the  State  Board 
of  Health  of  Massachusetts,  noted  that  a  marked  decrease  in  the  general 
death  rate  of  the  city,  and  not  merely  in  the  death  rate  from  t}q3hoid 
fever,  was  taking  place.  About  the  same  time  (May,  1893)  filtered  Elbe 
River  water  was  furnished  the  city  of  Hamburg,  and  Dr.  J.  J.  Reincke, 
health  officer  of  that  city,  in  his  successiA^e  annual  reports,  noticed  that 
the  general  death  rate  was  declining  more  rapidly  than  could  possibly  be 
accounted  for  by  the  deaths  from  typhoid  fever  alone.  To  this  important 
discovery  Sedgwick  and  MacNutt  have  given  the  name  of  the  "Mills- 
Eeincke  phenomenon,"  ^  In  1904  Mr.  Allen  Hazen,  a  sanitary  engineer, 
formulated  a  numerical  expression  for  the  comparative  effect  of  water 
purification  upon  typhoid  fever  mortality  and  total  mortality.  He  said 
that,  "where  one  death  from  typhoid  fever  has  been  avoided  by  the  use  of 
a  better  water,  a  certain  number  of  deaths,  probably  two  or  three,  from 
other  causes  have  been  avoided."  The  Mills-Reincke  phenomenon  and 
Hazen's  theorem  have  been  searchingly  studied  by  Sedgwick  and  MacNutt, 
and  the  student  is  advised  to  read  the  original  article  referred  to  in  the 
footnote.  These  authorities  examined  the  vital  statistics  of  the  cities  of 
Lawrence,  Mass.,  and  Hamburg,  Germany,  and  also  of  Lowell,  Mass., 
Albany,  Binghamton,  and  Watertown,  N.  Y.  They  found  abundant  evi- 
dence of  the  great  life-saving  power  of  a  purified  water  in  preventing 
many  diseases  other  than  typhoid  fever  in  the  cities  studied,  except  Water- 
town,  and  in  this  case  it  is  possible  that  the  purification  of  the  public 
water  supply  has  been  as  yet  relatively  imperfect.  It  is  further  to  be 
noted  that  the  method  of  purification  used  at  Watertown  is  mechanical 
filtration. 

Sedgwick  and  MacNutt  express  the  opinion  that  Mr.  Hazen's  theorem 
applied  to  the  cities  they  studied,  with  the  exception  of  Watertown, 
appears  to  be  sound  and  conservative.  In  Hamburg  the  saving  in  typhoid 
mortality  was  slight  in  comparison  with  the  saving  of  mortality  in 
other  diseases  combined;  that  is,  roughly,  only  about  1  to  16.  In  the 
other  cities  the  ratios  difi'ered  widely  from  this.  Thus,  at  Lawrence  it 
was  1  to  4.4,  at  Lowell  1  to  6.0,  in  Albany  about  1  to  4.1,  and  in  Bing- 
hamton only  about  1  to  1.5.    It  is  clear,  therefore,  that  Hazen's  theorem 

^W.  T.  Sedgwick  and  J.  S.  MacNutt:  "The  Mills-Eeincke  Phenomenon  and 
Hazen's  Theorem  Concerning  the  Decrease  of  Mortality  from  Diseases  Other 
Than  Typhoid  Fever  Following  the  Purification  of  Public  Water  Supplies,"  Jour. 
Infect.  Dis.,  Vol.  VII,  No.  4,  Aug.  24,  1910,  pp.  489-564. 


914 


WATEE  AND  ITS  in^]LAT10xV  TO   DISEASE 


is  merely  a  convenient  formula  rather  than  a  precise  mathematical  ex- 
pression. 

One  of  the  most  surprising  results  of  these  studies  is  the  disclosure 
of  the  remarkable  relation  existing  between  polluted  water  and  infant 
mortality.  This  was  emphasized  especially  by  Dr.  Eeincke  at  Hamburg. 
Closely  associated  with  infant  mortality  stand  diarrhea  and  gastro- 
intestinal disorders  in  relation  to  polluted  water,  which  now  bids  fair 
to  assume  a  causal  importance  in  these  diseases  second  only  to  that  of 
contaminated  milk. 

In  regard  to  tuberculosis  the  evidence,  though  less  striking,  is  in- 
teresting and  suggestive.  Sedgwick  and  MacNutt  state  that,  "inasmuch 
as  they  have  been  unable  even  after  the  most  careful  investigation  to 
discover  any  other  possible  explanation  of  the  figures,  they  are  forced 
to  the  conclusion  that  a  considerable  portion  of  the  decline  in  mortality 
from  tuberculosis  in  Lawrence  and  Lowell  during  the  years  immediately 
following  a  change  from  a  polluted  water  supply  was  due  to  that  change, 
and  in  line  with  this  conclusion  a  similar  explanation  appears  more  than 
probable  for  Hamburg.  A  somewhat  similar  relation  stands  for  pneu- 
monia, bronchitis,  and  the  acute  respiratory  diseases." 

The  question  naturally  arises  as  to  what  such  decline  of  mortality 
observed  in  the  Mills-Eeincke  phenomenon  for  diseases  other  than  typhoid 
fever  is  due.  The  natural  suggestion  is  that  it  either  results  from  an 
increased  vital  resistance  resulting  from  the  use  of  purer  water  or  an 
exclusion  of  the  disease  germs,  or  perhaps  the  phenomenon  might  be 
due  to  a  combination  and  cooperation  of  these  two  factors. 

EFFECT  OF  WATER  PURIFICATION— GENERAL   DEATH-RATE 


City 


General 
Death 
Rate 
Before 
Change  of 
Water 
Supply 


Providence,  R.  I . . 
St.  Louis,  Mo .... 
Youngstown,  O.  .  . 

Ithaca,  N.  Y 

Paducah,  Ky 

Water  town,  N.  Y . 
Paterson,  N.  J. .  .  . 
Binghamton,  N.  Y 

Average 


19.3 
18.0 
15.6 
16.4 
23.4 
15.5 
17.2 
17.6 


17.8 


Same 
After 


19.0 
16.1 
15.1 
15.1 

17.8 
17.2 
16.5 
17.6 


16.8 


Percent- 
age Re- 
duction 


+  1.6 
+  10.6 
+  3.2 
+  7.9 
+23.9 
—11.1 
+  4.1 
0 


+  5.7 


Typhoid 
Fever 
Death 
Rate 
Before 

Change  of 
Supply 


21.8 

39.2 

96.1 

108.8 

82.1 

100.6 

28.2 

40.8 


64.7 


Same 
After 


13.7 
19.1 
39.1 
25.3 

78.7 
38.2 
11.9 
13.4 


29.9 


Percent- 
age Re- 
duction 


+37.2 
+51.3 
+59.4 
+76.8 
+  4.2 
+62.1 
+57.8 
+67.2 


+53.8 


McLaughlin  ^  has  also  noted  the  relation  of  a  sewage-polluted  water 
to  infant  mortality,  and  concludes  that  it  is  certain  that  in  practically 
every  instance,  in  addition  to  a  lessened  number  of  deaths  from  typhoid 

^Public  Health   Rcporifs,  Vol.  XXVIT.  No.   17.  April  26,   1912. 


NON-SPECIFIC  DISEASES  DUE  TO  WATER  915 

fever,  the  substitution  of  a  safe  for  a  polluted  water  supply  results  in 
the  saving  of  many  lives  from  diseases  which  are  not  reported  as  typhoid 
fever.  Hazen's  theorem  has  also  been  studied  by  Arthur  Lederer/  who 
finds  a  large  number  of  affirmative  statistical  results  from  which,  together 
with  our  direct  and  indirect  proof  of  the  prevalence  of  water-borne  dis- 
eases, it  seems  safe  to  assume  that  the  influence  of  an  improved  water  sup- 
ply upon  the  death  rate  in  general  is  correct.  The  theorem  seems  well 
borne  out  by  the  figures  in  the  above  table. 

More  recent  evidence  from  Providence,  Cincinnati,  Columbus,  Pitts- 
burgh, and  Philadelphia  does  not  tend  to  bear  out  the  Mills-Eeincke 
theory,  except  perhaps  in  regard  to  diarrheal  diseases  in  Pittsburgh. 
The  proposition  is  not  demonstrated  and  it  would  be  exceedingly  imwise 
to  promise  a  marked  lowering  of  the  general  death  rate  as  a  result  of 
the  purification  of  water  supplies  alone. 

NON-SPECIFIC  DISEASES  DUE  TO  WATER 

Impure  water  is  responsible  for  disorders  other  than  the  specific  gas- 
tro-intestinal  infections,  but  these  disorders  are  often  obscure  or  over- 
looked. It  is  not  always  plain  just  what  quality  or  what  impurity  in 
the  water  is  responsible  for  these  non-specific  disorders,  and  the  dis- 
eases themselves  may  present  a  vague  and  ill-defined  clinical  picture. 
The  relationship  has  been  worked  out  in  only  a  few  instances. 

A  turbid  or  malodorous  water  may  not  in  itself  be  particularly  in- 
jurious to  health,  but,  on  account  of  its  unattractive  appearance  or  repul- 
sive condition,  less  may  be  taken  than  is  necessary  for  the  maintenance 
of  good  health.  In  this  way  water  may  be  indirectly  responsible  for 
much  harm.  The  drinking  of  too  little  water  is  a  very  common  dietetic 
error. 

While  a  polluted  water  may  not  carry  specific  germs,  it  may  so 
lindermine  health  or  lower  resistance  as  to  favor  infections  not  usually 
associated  with  the  digestive  tract,  such  as  pneumonia  and  tuberculosis 
and  the  diseases  responsible  for  infant  mortality. 

From  the  nature  of  the  case  the  effects  of  an  impure  water  cannot 
always  be  measured  by  gross  results,  but  the  cumulative  or  separate  action 
of  small  effects  often  repeated  may  result  in  deranged  digestion,  altered 
metabolism,  irritation  of  delicate  membranes  or  sensitive  organs  and 
structures,  which  may  lead  to  or  hasten  the  course  of  chronic  diseases. 

The  organic  matter  in  the  quantities  usually  contained  in  a  natural 
water  is  not  of  itself  harmful.  This  organic  matter,  however,  does  not 
stay  in  its  native  state,  but  soon  putrefies,  and  it  is  suspected  that  some 
of  the  intermediate  products  of  putrefaction  may  have  toxic  potency. 
Ordinarily  these  toxic  substances  are  in  minute  quantities,  or  at  least 

*  Arthur  Lederer :   Amer.  Journal  Public  Hygiene,  June,   1910,  p.  304. 


916  WATER  AND  ITS  RELATION  TO  DISEASE 

in  great  dilution,  but  under  certain  circumstances  they  may  accumulate 
in  noticeable  concentration.  Further,  while  persons  habitually  taking 
such  toxic  substances  may  soon  become  immune,  the  new-comer  will  not 
be  so  fortunate.  The  case  of  organic  matter  in  water  is  not  a  clear  one, 
and  sanitarians  have  ever  erred  on  the  safe  side  in  condemning  waters 
containing  much  organic  matter.  It  is  well  known  that  if  the  organic 
matter  is  not  derived  from  sewage  it  is  probably  harmless.  Thus,  in  the 
ease  of  organic  matter  of  vegetable  origin.  Mason  has  been  able  to  find 
but  few  cases  of  illness  traceable  to  peaty  waters.  In  such  instances  the 
patients  suffered  from  a  mild  and  transient  form  of  diarrhea.  I  am 
familiar  with  an  outbreak  of  diarrhea  traced  to  a  dead  fish  caught  in 
the  water  meter  of  a  hospital.  This  is  probably  a  type  of  water-borne 
disease  due  to  organic  pollution  which  is  not  infrequent.  Whether  in  such 
cases  the  trouble  is  due  to  bacteria  or  to  bacterial  toxins,  or  to  the  degra- 
dation products  of  protein  decomposition,  cannot  always  be  made  out. 

As  far  as  the  inorganic  impurities  usually  found  in  water  are  con- 
cerned, the  chlorids,  carbonates,  sulphates,  and  silicates,  and  lime,  mag- 
nesia, and  aluminium  can  scarcely  be  harmful  in  the  amounts  ordinarily 
found.  It  is  commonly  stated  that  water  containing  500  parts  per 
million,  or  30  grains  per  gallon,  of  clay  and  silt  is  unfit  for  drinking 
purposes,  on  account  of  its  irritating  effects  upon  the  gastro-intestinal 
tract;  but  beyond  this  probability,  turbidity  is  of  no  special  sanitary 
significance,  unless  the  water  also  contains  metallic  poisons  or  objection- 
able chemicals. 

An  attempt  has  frequently  been  made  to  correlate  the  formation  of 
concretions  such  as  urinary  and  biliary  calculi  with  the  inorganic  salts 
in  water.  We  now  know  that  biliary  calculi  usually  form  about  a  colon 
bacillus  or  a  typhoid  bacillus  or  about  some  pathological  particle  as  a 
nucleus,  and  that  urinary  calculi  probably  have  a  similar  pathogenesis. 
There  is  no  known  relation  betv/een  these  concretions  in  the  body  and 
the  inorganic  salts  in  water,  even  those  in  a  very  hard  water.  It  is  stated 
that  a  change  from  a  soft  to  a  hard  water  causes  diarrhea.  The  relation 
of  inorganic  substances  in  water  to  goiter  will  be  discussed  separately. 

Goiter, — Goiter  or  struma  is  a  chronic  enlargement  of  the  thyroid 
gland.  It  occurs  as  epidemics,  is  endemic  in  places,  and  sporadic  cases 
may  arise  anywhere.  Goiter  has  many  of  the  earmarks  of  an  infectious 
disease,  although  it  is  not  communicable  from  person  to  person,  the 
cause  being  derived  from  his  environment.  The  epidemics  are  usually 
of  short  duration,  limited  extent,  and  commonly  occur  in  goiter  regions. 

The  classic  home  of  endemic  goiter  is  in  the  Swiss  Alps.  In  cer- 
tain regions  of  these  mountains  it  is  very  prevalent.  Thus,  in  Pied- 
mont it  sometimes  affects  more  than  two  out  of  every  three  of  the  in- 
habitants. It  also  occurs  in  the  mountains  of  Austria,  France,  and 
Germany,  and  there  are  a  few  endemic  centers  in  Norway,  Sweden,  Fin- 


NON-SPECIFIC  DISEASES  DUE  TO  WATER  917 

land,  and  the  Baltic  provinces.  The  traditional  seat  of  goiter  in  Eng- 
land is  in  Derbyshire,  while  Sussex  and  Hampshire  have  also  been 
affected.  There  are  many  endemic  centers  in  the  mountains  of  Asia, 
Japan,  the  Asiatic  Islands,  Africa,  Mexico,  and  South  America.  The 
early  explorers  found  it  among  the  North  American  Indians,  as  Mun- 
sen  has  in  more  recent  times  in  the  Eskimos.  The  region  of  our  Great 
Lakes  shows  considerable  numbers;  also  in  sections  of  West  Virginia, 
but  in  the  United  States  and  Canada  the  goiters  are  not  large  and 
cretinism  is  rare.  The  absolute  number  of  goiter  subjects  in  countries 
with  endemics  of  severe  degree  is  of  great  social  and  economic  impor- 
tance. In  France,  Mayet  (1900)  estimates  the  number  at  400,000.  The, 
drain  on  the  country  is  better  expressed  by  the  number  of  cretins.  In 
Cisleithan,  Austria,  there  were  in  1883  a  total  of  12,815,  or  71  per  100,- 
000 ;  in  one  district  in  Styria  a  proportion  of  1,045  in  100,000.  In  Pied- 
mont, Lombardy,  and  Venetia  there  were  in  1883  12,882  cretins  in  a 
population  of  9,565,038  (Dock).  It  will  therefore  be  seen  that  this 
disease,  which  is  undoubtedly  preventable,  but  the  cause  of  which  has 
not  yet  been  satisfactorily  unraveled,  deserves  careful  study. 

Mules,  horses,  and  dogs  also  have  goiter,  though  not  constantly,  in 
endemic  centers.  Marine  and  Lenhart  also  observed  goiter  among  brook 
trout  in  fish  hatcheries.    Rats  and  mice  are  also  susceptible. 

Goiter  is  a  disease  which  is  caused  by  some  poison  or  possibly  in- 
fection taken  into  the  system  with  the  water  or  perhaps  some  other 
article  of  diet.  There  is  much  evidence  that  drinking  water  is  responsi- 
ble; also  some  that  it  is  not.  There  is  no  doubt  that  remarkably  good 
effects  have  been  obtained  in  Switzerland  and  Italy  by  the  introduction 
of  good  drinking  water.  For  a  long  time  glacial  waters  were  believed 
to  be  responsible,  but  this  view  has  now  been  abandoned  as  the  cause  of 
goiter.  Suspicion  has  fallen  upon  certain  inorganic  constituents  of  wa- 
ter, but  all  these  studies  have  resulted  negatively.  Thus  magnesium, 
limestone,  iron,  and  iodin  have  each  in  turn  been  accused.  Hard  water 
may  favor  goiter,  but  does  not  cause  it.  It  is  known  that  goiter  may 
occur  where  water  is  hard  or  soft,  or  in  water  with  or  without  iron.  The 
relation  of  iodin  in  water  to  goiter  is  an  attractive  theory.  It  is  known 
that  iodin  under  certain  circumstances  stimulates  the  function  of  the 
thyroid  gland  and  produces  the  train  of  symptoms  associated  with  ex- 
ophthalmic goiter.  There  is  a  suspicion  that  goiter  may  occur  as  the  re- 
sult of  water  deficient  in  iodin;  or  the  water  may  contain  some  sub- 
stance which  prevents  the  thyroid  from  taking  up  iodin,  the  goiter  being 
a  protection  hypertrophy. 

There  are  goiter  wells  in  France  and  Switzerland,  the  waters  of 
which  are  used  successfully  for  the  intentional  production  of  the  disease 
with  the  view  of  escaping  compulsory  military  service. 

The  relation  of  water  to  goiter  is  also  illustrated  in  Vienna.     This 


918  WATEE  AND  ITS  EELATION  TO  DISEASE 

city  long  boasted  of  the  best  water  among  all  European  cities.  It  is 
brought  in  long  aqueducts  and  subterranean  pipes  from  the  Schneeberg, 
a  mountain  group  about  6,000  feet  high  and  85  miles  to  the  north  of  the 
city.  This  water,  used  since  1872,  put  a  stop  to  typhoid  and  other 
gastro-intestinal  diseases.  The  water  comes  from  limestone  formations, 
and  has  a  low  degree  of  hardness,  owing  to  the  absence  of  vegetation 
upon  the  catchment  area.  Since  1873  the  number  of  goiters  in  Vienna 
have  increased  300  per  cent.,  and  popular  belief  always  pointed  to  the 
water  as  the  cause.  The  water  used  by  the  inhabitants  in  many  of  the 
goiter  regions  in  Switzerland  comes  from  similar  limestone  formations. 

Further  presumptive  evidence  that  goiter  is  a  water-borne  disease 
is  found  in  certain  villages  in  the  Gilgit  District  in  India.  Here  eight 
villages  adjacent  to  each  other  derive  their  water  from  a  neighboring 
stream,  and  all  are  badly  affected  with  goiter.  Another  village  in  the 
same  district  takes  its  water  from  a  spring  and  has  no  goiter. 

Another  instance  in  which  the  change  of  water  supply  is  said  to  have 
influenced  the  prevalence  of  goiter  is  that  of  the  village  of  Bozel  in 
Tarentaise.  In  this  village,  during  1848,  of  a  population  of  1472,  there 
were  900  cases  of  goiter  and  109  cretins.  About  this  time  a  new  water 
supply  was  introduced  from  a  source  only  800  meters  distant,  and  16 
years  afterwards,  among  practically  the  same  population,  there  were  only 
39  cases  of  goiter  and  58  cretins. 

Eepin  believes  that  goitrous  waters  are  radio-active  mineral  waters 
of  high  carbon  dioxid  content,  which  hold  an  excess  of  calcium  and 
magnesium  salts  in  solution. 

McCarrison  ^  believes  from  the  results  of  researches  upon  rats,  that 
the  excreta  of  the  human  or  animal  subject  seems  to  be  the  main  source 
of  the  disease,  and  with  which  house,  room,  cage  or  fish  tank  infection 
follows. 

It  has  recently  been  shown  that  "goiter"  is  very  common  in  trout 
in  certain  regions.  Thus,  in  our  own  endemic  area  about  the  Great 
Lakes  many  trout  have  enlarged  thyroid  glands.  In  trout  hatcheries 
almost  all  the  fish  may  suffer  from  goiters,  some  very  large,  provided 
three  conditions  are  present.  These  are:  (1)  overcrowding;  (2)  over- 
feeding; and  (3)  pollution  of  the  water.  It  is  stated  that  in  the  absence 
of  any  one  of  these  three  conditions  the  thyroid  glands  do  not  enlarge. 
Some  of  these  enlarged  glands  have  been  described  by  Gaylord  as  can- 
cerous. 

Marine  and  Lenhart,  and  also  Gaylord,  observed  the  occurrence  of 
goiter  in  trout  in  the  tanks  of  hatcheries,  where  the  tanks  are  arranged 
in  series  so  that  the  water  flows  from  one  to  the  next;  under  these  cir- 
cumstances there  is  very  little  or  no  goiter  among  the  fish  in  the  first  tank 
with  clear  water,  but  up  to  84  per  cent,  in  the  last  tank.     Furthermore 

'^Indian  Jour,  of  Med.  Res.,  Vol.  II,  No.   1,  July,  1914. 


NON-SPECIFIC  DISEASES  DUE  TO  WATEE  919 

goitrous  fish  removed  from  tliese  tanl^s  recover  when  placed  in  clean  fresh 
water. 

Marine  ^  believes  that  goiter  in  fish  is  a  non-infectious,  non-con- 
tagious symptomatic  manifestation  of  a  fault  of  nutrition,  the  exact 
biochemical  nature  of  which  has  not  been  determined.  Goiter  may  read- 
ily be  produced  in  fish  by  feeding  a  highly  artificial  and  incomplete  diet 
of  liver,  and  the  condition  may  at  once  be  corrected  by  feeding  whole  sea 
fish.  Marine  believes  that  the  water  itself  plays  no  essential  part  in  the 
etiology,  transmission  or  distribution  of  the  disease. 

For  the  reason  that  no  definite  correlation  has  been  demonstrated 
between  any  inorganic  impurity  i]i  a  water  and  the  occurrence  of  goiter, 
investigators  such  as  Kocher,  Ewald,  Bircher,  McCarrison  ^  and  others 
are  inclined  to  think  that  a  microorganism  is  the  cause  of  the  trouble. 
This  theory  would  explain  the  definite  endemic  distribution  of  the  dis- 
ease. 

Bircher  ^  has  shown  that  goiter  occurs  essentially  upon  marine  de- 
posits or  paleozoic,  triassic,  and  tertiary  periods,  whereas  volcanic  forma- 
tions, crystalline  rock  of  archaic  age,  stratified  deposits  of  the  Jura  and 
Kreidemeer,  and  all  fresh-water  deposits  are  free.  These  facts  led 
Wilms  *  to  assume  that  the  cause  of  goiter  is  not  a  living  organism,  but 
that  it  is  due  to  unknown  substances  derived  from  the  bodies  of  marine 
animals.  He  speculates  that  these  substances  may  be  toxalbumins  or 
ferments.  Experiments  upon  rats  show  that  water  from  a  goiter  well 
in  Basel  produces  hypertrophy  of  the  thyroid.  This,  however,  does  not 
occur  if  the  water  is  heated  above  80°  C.  The  hypertrophy  takes  place 
in  the  rats  who  drink  this  water  which  has  been  passed  through  a  Berke- 
feld  filter.  The  water  looks  clear  and  fine,  has  a  moderate  lime  con- 
tent, and  is  slightly  high  in  ammonia. 

Lobenhofl'er  ^  studied  the  presence  of  goiter  in  the  Unterfranken 
district.  In  some  of  the  towns  21  to  26  per  cent,  of  the  inhabitants  are 
affected.  The  endemic  regions  correspond  to  certain  geological  forma- 
tions from  which  the  drinking  water  is  derived.  Water  from  shell  lime- 
stone is  the  main  goiter  producer,  but  in  a  milder  degree  red  sandstone 
and  other  formations  are  involved.  Boiling  the  water  seems  to  do 
away  with  its  goiter-producing  properties.  Lobenhoffer  believes  that  the 
latest  researches  in  regard  to  the  causal  agent  of  goiter  seem  to  demon- 
strate that  it  is  a  purely  chemical  substratum  substance  which  enters 
the  water  as  a  toxin,  but  whicli  is  certainly  destroyed  at  70°  C.    He  also 

^Jour.  of  Exp.  Med.,  New  York,  Jan.,  191.3.  XIX,  1,  pp.  1-120.— Reid  Hunt 
in  1910  showed  that  mice  fed  on  liver  developed  enlarged  thyroids. 

^McCarrison,  Robert:  Lancet,  Jan.  18  and  25,  and  Feb.  8,  1913. 

^Med.  Klinik,  1908,  Heft  6. 

*  Deutsche  med.  Wochenschr.,  March  31,  1910,  p.  604. 

'Lobenhoffer,  W. :  "Die  Verbreitung  des  Kropfes  in  Unterfranken,"  Mit- 
teihing  aus  den  Grenzgehieten  der  Med.  und  Chir.,  Jena,  XXIV,  No.  3,  pp. 
383-606. 


920  WATER  AND  ITS  RELATION  TO  DISEASE 

believes  that  it  is  possible  that  filtering  through  certain  substances  or 
treating  with  ultraviolet  rays  may  have  the  same  effect. 

The  prevention  of  goiter  therefore  consists  in  the  elimination  of  fac- 
tors that  are  known  or  suspected  of  being  able  to  produce  the  disease,  such 
as  water  from  certain  sources.  If  possible,  persons  in  predisposed  families 
should  leave  goiter  districts  and  live  in  healthy  localities.  The  drinking 
water  should  be  boiled,  for  experimental  evidence  demonstrates  that 
the  "poison,''  whatever  it  may  be,  in  water  is  destroyed  by  boiling.  Fil- 
tration is  not  sufficient,  for  experiments  have  shown  that  it  will  pass  a 
Berkefeld  filter.  Tight  collars  and  occupations  that  induce  congestion 
of  the  head  should  be  avoided.  The  satisfactory  control  of  the  disease 
must  await  further  studies  into  its  causation.  In  the  meantime  im- 
proved sanitation  in  its  broadest  sense  would  doubtless  diminish  the 
incidence  to  this  disease.     (Page  785.) 

Lead  Poisoning. — Lead  is  practically  never  found  in  natural  waters. 
The  source  of  the  lead  in  the  water  is  almost  always  lead  service  pipes, 
or  some  other  lead  object  used  in  collecting,  storing,  or  delivering  the 
water.  Lead  is  the  most  dangerous  inorganic  substance  with  which 
our  drinking  water  is  ordinarily  contaminated.  Lead  poisoning  from 
this  source  is  much  more  common  than  it  is  given  credit  for.  A  cele- 
brated instance  of  lead  poisoning  occurred  in  Lancashire  and  York- 
shire, England.  The  water  came  from  peaty  moorlands  and  was  de- 
livered through  lead  pipes.  The  citizens  of  these  towns  experienced  a 
mysterious  bodily  derangement  for  some  years,  until  it  was  finally  dis- 
covered that  lead  poisoning  was  prevalent.  In  man}'-  other  places,  as 
Somerfeld,  Germany,  and  Lowell,  Mass.,  numerous  cases  of  lead  poison- 
ing due  to  the  action  of  water  in  lead  pipes  have  been  reported. 

Enormous  quantities  of  lead  services  pipes  are  still  in  use,  not  only 
in  the  old  plumbing,  but  in  the  newer  installations.  It  is  so  pliable 
that  plumbers  find  it  much  easier  to  bend  it  around  corners  and  angles 
than  to  make  the  usual  connections  with  iron  or  brass  pipe,  and  it  is 
therefore  a  great  temptation  to  put  in  short  lengths  of  it  in  difficult 
places.  Lead  poisoning  may,  under  certain  circumstances,  come  from 
a  few  feet  of  lead  pipe.  The  various  factors  that  determine  the  corro- 
sive action  of  water  upon  lead  are  very  complex.  It  is  not  possible  to 
determine  by  chemical  tests  whether  or  not  a  water  has  plumbo-solvent 
action.  All  natural  waters  have  some  solvent  power.  The  only  sure 
method  of  determining  to  what  degree  a  given  water  will  take  up  lead 
is  by  testing  the  question  experimentally  under  practical  conditions  and 
establishing  the  amount  of  lead  taken  up. 

The  way  by  which  water  takes  up  lead  is  first  through  the  formation 
of  lead  oxid.  This  oxidation  is  favored  by  the  amount  of  oxygen  car- 
ried in  the  water,  possibly  aided  by  the  nitrates  and  nitrites  serving 
as  oxygen  carriers.     The  lead  oxid  may  then  be  dissolved,  more  rapidly 


NOX-SPECIFIC  DISEASES  DUE  TO  WATEE  921 

if  the  water  is  acid,  or  may  be  washed  away  by  the  currents  in  the  state 
of  a  fine  powder  in  suspension. 

As  a  general  rule  clean  (pure)  waters  have  a  greater  corrosive  action 
upon  lead  than  turbid  waters.  This  is  partly  for  the  reason  that  the 
mud  coats  the  pipes  and  protects  them  mechanically.  Acid  waters  are 
almost  sure  to  take  up  lead  if  allowed  to  come  in  contact  with  that 
metal.  Even  so  feeble  an  acid  as  carbonic  acid  may  under  certain  cir- 
cumstances greatly  increase  the  plumbo-solvent  action  of  water.  Soda 
water  (highly  charged  with  CO2  under  pressure)  takes  up  relatively 
large  quantities;  as  if  lead  pipes  are  used  in  soda  water  fountains  or 
"syphon"  bottles.  Waters  containing  carbonates  or  sulphates  are  not 
apt  to  take  up  lead  because  the  corresponding  salts  of  lead  are  insoluble, 
and  thus  form  a  protecting  coating.  Even  though  a  water  has  no  plum- 
bo-solvent action,  the  use  of  lead  piping,  lead  cooking  utensils,  lead- 
lined  cisterns,  etc.,  is  entirely  unjustified  for  domestic  service,  for 
the  reason  that  under  certain  circumstances  electrolytic  action,  changes 
in  the  character  of  the  water,  or  other  causes  may  lead  to  lead  poisoning. 

Various  conditions  affect  the  plumbo-solvent  action  of  water,  such 
as  the  duration  of  contact,  the  temperature,  the  pressure,  the  season  of 
the  year,  the  purity  of  the  lead,  etc.  Water  remaining  in  the  pipes 
all  night  naturally  takes  up  more  lead  than  the  water  that  flows  more 
or  less  rapidly  during  the  day.  Lead  pipes  were  formerly  used  in  soda 
water  fountains  and  the  employee  who  took  the  first  drink  in  the  morn- 
ing before  the  proprietor  arrived  received  a  concentrated  dose.  Hot 
water  has  a  greater  solvent  action  than  cold  water;  so,  also,  increase  in 
pressure  up  to  140  pounds  to  the  square  inch.  For  some  unexplained 
reason  more  lead  is  often  found  in  the  water  during  the  winter  than 
during  the  summer.  The  purer  the  lead  in  the  pipes  the  freer  the 
solvent  action.  New  pipes  give  up  more  lead  than  old  pipes.  However, 
in  some  cases  the  poisoning  manifested  itself  only  after  the  pipe  had 
been  in  use  for  years.  Lead  pipes  are  purer  now  than  formerly,  owing 
to  profitable  methods  of  extracting  the  silver  and  other  metals  with 
which  it  is  frequently  associated.  If  the  lead  is  combined  with  copper, 
zinc,  or  tin  the  lead  passes  into  the  water  more  quickly  in  consequence 
of  galvanic  action  than  when  pure  lead  is  used.  Electrolytic  action 
favors  the  solution  of  lead,  and  the  modern  method  of  grounding  electric 
currents  adds  to  the  danger. 

The  various  conditions  of  water  that  favor  plumbo-solvent  action  are : 
Those  containing  free  acid,  such  as  soft,  peaty  waters;  those  containing 
much  oxygen  and  little  dissolved  salts,  that  is,  soft  waters,  such  as 
rain  water;  those  containing  organic  matter,  nitrites,  and  nitrates,  that 
is,  sewage-contaminated  water  in  the  stage  of  oxidation;  those  contain- 
ing chlorids,  because  chlorids  dissolve  the  protecting  film  of  carbonates. 
Waters  that  act  least  upon  lead  are  turbid  waters  and  hard  waters. 


923  WATER  AND  l^l^S  RELATION  TO  DISEASE 

especially  those  coiitainiiig  free  CO2,  for  here  again  carbonates  are 
formed  which  protect  the  water  with  an  insoluble  film.  However,  if 
CO2  is  present  in  excess  or  under  pressure  the  carbonates  are  redissolved. 

It  will  therefore  be  seen  that  the  purest,  softest,  and  best  aerated 
waters  are  especially  prone  to  act  upon  lead.  Distilled  water  will  take 
up  lead  even  from  impure  zinc  pipes  (containing  some  lead)  used  on 
board  ships.  Absolutely  pure  water  probably  has  no  appreciable  action 
upon  metals  such  as  lead,  iron,  and  zinc,  but  absolutely  pure  waters 
are  not  found  in  nature.  The  plumbo-solvent  action  is  in  part  a  me- 
chanical erosion,  in  part  a  chemical  solution,  and  in  part  results  from 
electrolytic  action. 

Symptoms. — The  symptoms  of  lead  poisoning  are  sometimes  vague 
and  readily  overlooked.  Fatal  poisoning  may  be  caused  when  very  little 
lead  is  taken  with  the  water  each  day;  the  action  is  cumulative  and  the 
course  of  the  intoxication  is  chronic;  the  immediate  and  remote  effects 
are  serious.^ 

The  usual  symptoms  of  chronic  lead  poisoning  are  anemia,  dyspepsia, 
depression,  constipation,  colic;  various  forms  of  paralysis,  especially 
paralysis  of  the  extensor  muscles  of  the  forearm  leading  to  wrist-drop ;  a 
Ijlue  line  along  the  edges  of  the  gums,  due  to  the  formation  of  sulphid 
of  lead  deposited  in  the  tissues.  Optic  neuritis  may  come  on.  There 
is  an  increase  in  the  blood  pressure.  Chronic  lead  poisoning  leads  to 
arteriosclerosis,  fibrosis  of  the  kidneys,  and  the  remote  consequences  of 
these  changes.  Muscular  paresis,  pain  and  swelling  of  the  joints,  often 
occur  and  may  be  mistaken  for  "rheumatism."  In  some  cases  gout  is 
closely  simulated.    The  pain  is  usually  worse  at  night. 

The  individual  susceptibility  to  lead  poisoning  varies  remarkably. 
Of  a  number  of  individuals  equally  exposed  some  will  suffer  and  others 
escape.  Of  those  who  suffer  the  degree  of  intoxication  varies  consid- 
erably. It  is  quite  common  to  find  that  among  the  members  of  a  family 
using  a  water  containing  lead  only  one  is  stricken,  while  the  others  seem 
to  be  "immune";  that  is,  they  either  do  not  absorb  the  lead  or  are  able 
to  eliminate  it. 

Mild  cases  of  lead  i^oisoning  may  show  only  symptoms  of  anemia, 
vague  or  fugitive  pains,  or  a  mild  type  of  peripheral  neuritis.  This  stage 
of  lead  poisoning,  which  does  not  vary  essentially  from  other  intoxica- 
tions of  mild  degree,  is  readily  overlooked  clinically. 

Lead  is  absorbed  from  the  intestines  and  eliminated  by  the  kidney? 
and  the  liver.  It  therefore  may  appear  in  either  the  urine  or  feces. 
Lead  in  the  urine  is  always  associated  with  albumin,  and  may  be  inter- 
mittent. That  is,  a  well-marked  case  of  lead  poisoning  may  excrete 
urine  free  from  both  lead  and  albumin.  However,  if  the  feces  are 
examined  they  will  be  found  to  contain  lead. 

^li'or  further  discussion  of  Lead  Poisoning,   see  page  1047. 


SPECIFIC  DISEASES  DUE  TO  WATEE  923 

Xead  poisoning  may  occur  when  a  comiDaratively  small  surface  of 
lead  is  exposed  to  the  solvent  action  of  the  water.  This  is  well  illus- 
trated in  the  following  cases  :^ 

Case  1. — A  man  about  fifty  years  old  contracted  lead  poisoning  from 
using  cistern  water.  Twelve  feet  of  the  service  pipe  was  lead,  and 
almost  wholly  in  the  water,  as  it  was  bent  at  right  angles  and  ran 
across  the  cistern  under  the  water. 

Case  2. — Mrs.  W.,  sixty-six  years  of  age,  contracted  lead  poisoning 
from  a  well  water  which  was  contaminated  from  an  old  lead  clock 
weight  which  had  been  accidentally  dropped  into  the  well.  The  clock 
weight  had  been  in  the  water  about  fourteen  months  before  the  appear- 
ance of  symptoms.  The  well  was  pumped  free  of  water  and  the  clock 
weight  found  and  removed.  In  two  weeks  from  this  time  Mrs.  W. 
noticed  an  improvement  in  her  lameness,  and  in  four  months  she  was 
entirely  well. 

Case  3. — In  this  case  the  patient  was  poisoned  by  cistern  water 
pumped  through  10  feet  of  lead  pipe.  The  symptoms  were  acute  mul- 
tiple peripheral  neuritis,  with  extensive  paralysis.  After  the  lead  in 
the  water  was  removed  recovery  was  only  partial  after  a  period  of  two 
years. 

The  exact  amount  of  lead  which  may  be  taken  into  the  system  with- 
out producing  harm  is  not  definitely  known,  and  doubtless  varies  with 
different  people,  but  it  is  known  that  the  continuous  use  of  water  con- 
taining quantities  of  lead  as  small  as  0.005  of  a  part  per  million,  or  about 
1/33  of  a  grain  per  gallon,  has  caused  serious  injury  to  health.^ 

ISTo  instances  have  been  recorded  of  ill  effects  upon  health  of  persons 
drinking  water  due  to  copper  or  zinc-lined  pipes. 


SPECIFIC  DISEASES  DUE  TO  WATER 

The  principal  disease  of  man  contracted  by  drinking  infected  water 
are  typhoid  fever,  cholera,  and  dysentery.  Water-borne  epidemics  of 
these  diseases  have  frequently  occurred  in  the  history  of  the  world. 
It  should  be  remembered  that  endemic  and  sporadic  cases  may  also  con- 
tract their  infections  through  water.  The  great  water-borne  tragedies 
have  for  a  time  occupied  an  exaggerated  position.  They  overshadowed 
the  less  dramatic,  but  more  insidious,  and  nevertheless  frequent  modes 
of  transmission  of  infection  through  other  channels,  especially  "con- 
tacts." It  is  only  in  recent  years,  since  the  water  supplies  of  most  of 
our  large  communities  have  been  very  much  improved,  so  that  water- 
borne  epidemics  have  been  excluded,  that  sanitarians  have  appreciated 

^Bull.  State  Board  of  Health,  Maine,  Jan.,  1909,  Vol.  1,  No.  21. 
''Mass.  State  Board  of  Health  Ann.   Report,   1898,  p.  XXXII. 


924  WATER  AND  ITS  RELATION  TO  DISEASE 

the  quantitative  role  played  by  water  as  a  medium  of  convection  in 
distributing  pathogenic  microorganisms. 

It  is  worthy  of  note  that  almost  all  the  large  water-borne  outbreaks 
that  have  been  investigated  have  been  traced  to  a  quick  transfer  of  the 
infected  material  from  the  patient  to  the  victim.  Even  in  Pittsburgh 
the  Typhoid  Fever  Commission  showed  that  most  of  the  fever  there  had 
been  due  to  nearby  rather  than  to  remote  pollution  of  the  river.  The 
greater  the  distance  and  the  longer  the  time  between  the  source  of  the 
infection  and  the  use  of  the  water,  the  less  are  the  chances  of  harm. 
This  we  now  understand  as  the  result  of  several  factors  which  have  been 
discussed. 

It  is  doubtful  whether  typhoid,  cholera,  or  dysentery  bacilli  multiply 
in  water  under  natural  conditions,  certainly  to  no  great  extent.  Almost 
all  the  great  water-borne  epidemics  of  typhoid  fever  occur  in  the  spring, 
winter,  or  fall  of  the  year,  when  the  water  is  very  cold.  Water-borne 
epidemics  of  typhoid  in  the  summertime,  when  the  conditions  seem 
favorable  for  multiplication  of  the  bacilli,  are  relatively  infrequent. 
Assuming  that  in  the  case  of  typhoid  there  is  no  multiplication  of  the 
bacilli  in  the  water,  the  dilution  must  have  been  enormous  in  many  of 
the  cases  recorded ;  that  is,  there  must  have  been  very  few  typhoid  bacilli 
in  a  tumblerful  of  water.  If  these  facts  are  correct  it  illustrates  how 
very  few  bacteria,  when  fresh  and  virulent,  may  induce  disease.  The 
experimental  data  from  the  laboratory  indicate  that  the  healthy  organ- 
ism may,  as  a  rule,  successfully  overcome  small  doses  of  infection.  Feed- 
ing experiments,  especially  upon  the  lower  animals,  under  laboratory 
conditions,  indicate  that  very  large  numbers  of  microorganisms  are 
usually  necessary  to  induce  disease  when  administered  by  the  m.outh. 
This  is  only  one  of  the  many  discrepancies  between  laboratory  and 
natural  conditions.  Many  large  epidemics  have  been  traced  to  indi- 
vidual instances  of  pollution.  In  the  typhoid  epidemics  at  Butler,  Plym- 
outh, New  Haven,  in  Nanticoke  and  Reading,  there  were  collectively 
3,929  cases  of  typhoid  fever,  with  301  deaths,  resulting  from  the  care- 
less treatment  of  the  discharges  of  but  one  individual  patient  in  each 
outbreak. 

Outbreaks  due  to  water  are  usually  caused  by  the  contamination  of 
surface  supplies;  less  often  by  wells  and  springs.  It  is  self-evident 
that  the  great  epidemics  have  always  been  caused  by  polluted  river  or 
lake  waters,  and  not  by  ground  waters.  Ground  water  is  sometimes 
responsible  for  outbreaks  of  typhoid  fever,  especially  in  limestone  dis- 
tricts, as  at  Lausen,  Switzerland;  Paris,  France,  etc.  Usually  when  a 
well  becomes  badly  infected  it  is  from  a  nearby  privy  or  broken  sewer 
underground,  as  in  the  instance  of  the  Broad  Street  cholera  epidemic  in 
London. 

Epidemics  from  public  water  supplies  result  from  contamination  by 


SPECIFIC  DISEASES  DUE  TO  WATER  925 

various  factors.  The  use  of  a  raw  water  into  which  is  continually  dis- 
charged the  sewage  of  other  towns  has  occurred  at  Pittsburgh,  Law- 
rence, Niagara  Falls,  Albany,  and  Philadelphia.  A  city  may  drink 
the  water  of  a  lake  which  has  become  its  own  cesspool,  as  did  Chicago, 
Cleveland,  and  Burlington.  The  pollution  may  come  from  the  wastes 
of  individual  houses,  as  at  Plymouth,  or  from  institutions  or  factories; 
or  the  pollution  may  come  from  privies  situated  directly  over  the  stream 
or  on  its  banks,  as  at  Ithaca ;  or  the  pollution  may  come  indirectly  after 
the  offending  matter  has  been  deposited  on  the  surface  of  the  ground, 
later  gaining  access  to  the  water  course  by  the  washing  of  rain  or  seep- 
age through  ground  seams.  In  some  instances  epidemics  originate 
through  criminal  thoughtlessness  in  a  town  that  has  been  supplied  with 
a  pure  or  purified  water.  Thus  a  water  pipe  laid  through  a  polluted 
pond  may  become  sufficiently  disjointed  to  permit  admission  of  the  in- 
fected water,  as  occurred  at  Baraboo,  Wis.,  and  Palmerton,  Pa.  The 
admission  of  polluted  water  to  a  pure  city  supply  at  any  time  is  inexcus- 
able. Epidemics  have  originated  as  a  result  of  the  unusual  drain  upon 
the  water  supply  at  times  of  fire,  as  in  the  case  of  Lawrence;  or  through 
failure  of  valves  to  operate,  as  in  the  case  of  Wilkinsburg,  Pa.,  wheu 
the  ordinary  water  supply  was  judged  to  be  insufficient  and  no  public 
warning  was  given  of  the  substitution  as  at  ISTewburyport ;  or  when 
polluted  water  was  furnished  temporarily  while  the  filter  plant  was 
undergoing  repair,  as  at  Lawrence,  Mass.,  in  1902,  in  Brewer,  in  Pough- 
keepsie,  IST.  Y.,  and  Millinocket,  Me.  A^arious  public  wells  have  become 
infected  through  ground  seams,  and  have  thus  caused  epidemics  of 
typhoid  fever  at  Trenton,  Newport,  and  Mt.  Savage,  Md.^ 

In  addition  to  the  usual  sources  of  pollution  of  a  surface  water, 
the  following,  while  relatively  infrequent,  may  be  particularly  dangerous, 
for  the  reason  that  they  are  apt  to  take  place  near  the  source  of  supply : 
discharges  from  water-closets  of  railroad  trains  while  crossing  bridges 
or  passing  the  banks  of  reservoirs  and  streams;  picnic  parties;  camping 
parties;  construction  gangs;  fishermen;  ferryboats  and  other  craft  upon 
navigable  streams.  The  large  boats  plying  our  Great  Lakes  may  dis- 
charge dangerous  and  obnoxious  material  very  near  an  intake. 

Cholera. — Cholera  in  London  in  1854 — The  Case  of  the  Broad 
Street  Pump. — Cholera  was  prevalent  in  London  in  1854,  but  prevailed 
with  epidemic  intensity  in  the  district  about  Broad  Street.  This  focus 
was  conspicuously  circumscribed  in  area,  and  the  disease  was  virulent, 
with  great  fatality.  This  case  has  become  classic  because  it  was  one 
of  the  earliest  instances,  if  not  the  first,  in  which  water  was  proved  to 
convey  a  specific  disease.  The  circumstances  were  studied  by  Dr.  John 
Snow  and  by  Mr.  John  York,  Secretary  and  Surveyor  of  the  Cholera 

^Harold  B.  Wood:  "The  Economic  Value  of  Protecting  the  Water  Sup- 
plies," J.  A.  M.  A.,  Oct.  2,   1909,  p.   1093. 


926 


WATEK  AND  ITS  EELATJOiM  TO  DISEASE 


Inquiry  Committee.^  No  less  than  700  deaths  occurred  in  St.  James 
Parish  during  the  seventeen  weeks  that  the  cholera  raged.  The  death 
rate  was  230  per  10;,000  in  the  parish,  which  contained  a  population  in 
1851  of  36,406.  In  the  adjoining  districts  the  death  rate  varied  from 
9  to  33  per  10,000. 

Dr.  Snow  made  a  careful  epidemiological  study  of  the  outbreak  and 
compiled  a  statistical  statement  of  special  value,  which  is  here  given  in 
its  original  form. 


The  Broad  Street  (London)  well  and  deaths  from  Asiatic  cholera  near  it  in  1864 


Date 

Number 
of  Fatal 
Attacks 

Deaths 

Date 

Number 
of  Fatal 
Attacks 

Deaths 

Aug.  19 

8 

56 

143 

116 

54 

46 

36 

20 

28 

12 

11 

5 

1 

0 

2 
0 
0 
2 
0 
0 

1 

0 

1 

2 
3 
70 
127 
76 
71 
45 
37 
32 
30 
24 
18 

Sept.  11 

5 
1 
3 
0 
1 
4 
2 
3 
0 
0 
2 

0 
0 
0 

45 

15 

Aug.  20 

Sept.  12 

6 

Aug.  21 

Sept.  13 

13 

Aug.  22 

Sept.  14 

6 

Aug.  23 

Sept.  15 

8 

Aug.  24 

Sept.  16     ... 

6 

Aug.  25 

Sept.  17 

5 

Aug.  26 

Sept.  18 

2 

Aug.  27 

Sept.  19  

3 

Aug.  28 

Sept.  20        .  . 

0 

Aug.  29 

Sept.  21 

0 

Aug.  30 

Sept.  22 

2 

Aug.  31 

Sept.  23    

3 

Sept.  1 

Sept.  24       .... 

0 

Sept.  2 

Sept.  25 

0 

Sept.  3 

Sept  26 

2 

Sept.  4 

Sept.  27 

0 

Sept.  5. 

Sept.  28    

2 

Sept.  6 

Sept.  29.  ." 

0 

Sept.  7 

Sept.  30 

0 

Sept.  8 

Date  unknown 

Total 

0 

Sept  9 

Sept.  10 

616 

616 

Many  of  the  facts  of  this  epidemic  are  taken  from  Sedgwick's  excel- 
lent account  in  his  "Principles  of  Sanitary  Science  and  the  Public 
Health,"  1902,  which  the  student  is  advised  to  read. 

It  will  be  seen  that  the  disease  broke  out  with  special  intensity  upon 
August  30  and  declined  noticeably  after  September  10.  The  pump 
had  been  removed  on  September  8.  Dr.  Snow's  inquiry  showed  that 
most  of  the  victims  had  preferred  or  had  access  to  the  water  of  the 
Broad  Street  well,  and  only  in  a  few  cases  was  it  impossible  to  trace 
any  connection  with  that  source.  Thus,  with  regard  to  73  deaths  occur- 
ring in  the  locality  of  the  pump  and  studied  especially  with  reference 
to  this  point,  it  was  found  that  there  were  61  instances  in  which  the 

^The  complete  original  report  is  entitled  "Report  on  the  Cholera  Outbreak 
in  the  Parish  of  St.  James,  Westminster,  during  the  Autumn  of  18.54.  Presented 
to  the  Vestry  by  the  Cholera  Inquiry  Committee,  July,  1855."  London,  J. 
Churchill,  1855. 


SPECIFIC  DISEASES  DUE  TO  WATEE 


927 


deceased  persons  used  to  drink  the,  water  from  the  pnmp  in  Broad 
Street,  either  constantly  or  occasionally.  In  6  instances  no  information 
could  be  obtained,  and  in  6  cases  it  was  stated  that  the  deceased  persons 
did  not  drink  the  pump  water  before  their  illness. 

On  the  other  hand,  Dr.  Snow  discovered  that,  while  a  workhouse 
(almshouse)  in  Poland  Street  was  three-fourths  surrounded  by  houses 
in  which  cholera  deaths  occurred,  out  of  535  inmates  of  the  workhouse 


«^ 


ASIATIC  CHOLERA 

THE  BROAD  STREET  PUMR 
LONDON  1654. 


•  ^LOCATION  OF  I^UMPS. 

•  •  LOCATIOM  OF  FATAL  CHOLERA  CASES 

— — BounoABy  or  equal  oisTAncES  betweDv^, 

BROAD  STREET   PUMP  AHO  ,.'i>iiS?     ^ 

OTHER    PUMPS. 


(AFTER  THC  0RI«I»4AL  MAP  BY 

OR.  joHn  snow.) 


Fig.  114. 

only  5  cholera  deaths  occurred.  The  workhouse,  however,  had  a  well  of 
its  own  in  addition  to  the  city  supply,  and  never  sent  for  water  to  the 
Broad  Street  pump.  If  the  cholera  mortality  in  the  workhouse  had 
been  equal  to  that  in  its  immediate  vicinity  it  should  have  had  50 
deaths. 

A  brewery  in  Broad  Street  employing  seventy  workmen  was  entirely 
exempt,  but,  having  a  well  of  its  own,  and  allowances  of  malt  liquor 
having  been  customarily  made  to  the  employees,  it  appeared  likely  that 
the  proprietor  was  right  in  his  belief  that  resort  was  never  had  to  the 
Broad  Street  well. 


338  WATEE  AFD  ITS  EELATTON  TO  DISEASE 

It  was  quite  otherwise  in  a  cartridge  factory  at  No.  38  Broad  Street, 
where  ahout  200  workpeople  were  employed,  two  tubs  of  drinking  water 
having  been  kept  on  the  premises  and  always  filled  from  the  Broad 
Street  well.  Among  these  employees  eighteen  died  of  cholera.  Similar 
facts  were  elicited  for  other  factories  on  the  same  street,  all  tending  to 
show  that  in  general  those  who  drank  the  water  from  the  Broad  Street 
well  suffered  either  from,  cholera  or  diarrhea,  while  those  who  did  not 
drink  that  water  escaped.  The  whole  chain  of  evidence  was  made 
absolutely  conclusive  by  several  remarkable  and  striking  cases  in  Dr. 
Snow's  report  like  the  following: 

"A  gentleman  in  delicate  health  was  sent  for  from  Brighton  to  see 
his  brother  at  No.  6  Poland  Street  who  was  attacked  with  cholera  and 
died  in  twelve  hours,  on  the  first  of  September.  The  gentleman  arrived 
after  his  brother's  death,  and  did  not  see  the  body.  He  only  stayed 
about  twenty  minutes  in  the  house,  where  he  took  a  hasty  and  scanty 
luncheon  of  rump  steak,  taking  with  it  a  small  tumbler  of  cold  brandy 
and  water,  the  water  being  from  the  Broad  Street  pump.  He  went  to 
Pentonville,  and  was  attacked  with  cholera  on  the  evening  of  the  fol- 
lowing day,  September  2,  and  died  the  next  evening." 

"The  deaths  of  Mrs.  E.  and  her  niece,  who  drank  the  water  from 
Broad  Street  at  the  West  End,  Hampstead,  deserve  especially  to  be 
noticed.  I  was  informed  by  Mrs.  E.'s  son  that  his  mother  had  not 
been  in  the  neighborhood  of  Broad  Street  for  many  months.  A  cart  went 
from  Broad  Street  to  West  End  every  day,  and  it  was  the  custom  to 
take  out  a  large  bottle  of  the  water  from  the  pump  in  Broad  Street,  as 
she  preferred  it.  The  water  was  taken  out  on  Thursday,  the  31st  of 
August,  and  she  drank  of  it  in  the  evening  and  also  on  Friday.  She 
was  seized  with  cholera  on  the  evening  of  the  latter  day,  and  died  on 
Saturday.  A  niece  who  was  on  a  visit  to  this  lady  also  drank  of  the 
water.  She  returned  to  her  residence,  a  high  and  healthy  part  of 
Islington,  was  attacked  with  cholera,  and  died  also.  There  was  no 
cholera  at  this  time,  either  at  West  End  or  in  the  neighborhood  where 
the  niece  died.  Besides  these  two  persons  only  one  servant  partook  of 
the  water  at  West  End,  Hampstead,  and  she  did  not  suffer,  or,  at  least, 
not  severely.    She  had  diarrhea." 

Mr.  York,  Secretary  and  Surveyor  of  the  Cholera  Inquiry  Commit- 
tee, was  instructed  to  survey  the  locality  and  examine  the  well,  cess- 
pool, and  drains  at  No.  40  Broad  Street.  His  report  revealed  the  fol- 
lowing condition  of  affairs:  The  well  was  circular  in  section,  28  feet 
10  inches  deep,  6  feet  in  diameter,  lined  with  brick,  and  when  examined 
(April,  1855)  contained  7  feet  6  inches  of  water.  It  was  arched  in  at 
the  top,  dome  fashion,  and  tightly  closed  at  a  level  3  feet  6  inches 
below  the  street  by  a  cover  occupying  the  crest  of  the  dome.  The  bot- 
tom of  the  main  drain  of  the  house  from  No.  40  Broad  Street  lay  9  feet 


SPECIFIC  DISEASES  DUE  TO  WATER 


929 


2  inches  above  the  water  level,  and  one  of  its  sides  was  distant  from 
the  brick  lining  of  the  well  only  2  feet  8  inches.  This  was  an  old- 
fashion  drain  12  inches  wide,  with  brick  sides ;  the  top  and  bottom  were 
made  with  old  stone.  It  had  a  small  fall  to  the  main  sewer.  The  mor- 
tar joints  of  the  old  stone  bottom  were  found  to  be  perished,  as  was  also 
the  jointing  of  the  brick  sides,  which  had  brought  the  brickwork  into 
the  condition  of  a  sieve,  and  through  which  the  house  drainage  must 
have  percolated  for  a  considerable  period.  Dr.  Snow  found  the  cesspool 
intended  for  a  trap,  but  misconstriicted,  and  upon  and  over  a  part  of 
the     cesspool     a     common 


UNE  or  rRONT. 


i 

I 

11 


fh 


L_. 


WATER      LINE. 


privy,  without  water  supply, 
for  the  use  of  the  house  had 
been  erected.  The  brick- 
work of  the  cesspool  was 
found  to  be  in  the  same  de- 
cayed condition  as  the 
drain.  Dr.  Snow  states 
that,  "from  the  charged 
condition  of  the  cesspool, 
the  defective  state  of  its 
brickwork,  and  also  that  of 
the  drain,  no  doubt  remains 
upon  my  mind  that  con- 
stant percolation,  and  for  a 
considerable  period,  had 
been  conveying  fluid  matter 
from  the  drains  into  the 
well.  A  washed  appearance 
of  the  ground  and  gravel 
flow  corroborated  this  as- 
sumption. The  ground  be- 
tween the  cesspool  and  the 
well   was    black,    saturated, 

and  in  a  swampy  condition,  clearly  demonstrating  the  fact."  This  evi- 
dence, while  only  circumstantial,  is  sufficient  to  connect  the  cesspool  with 
the  well,  and  can  leave  no  doubt  in  the  minds  of  those  who  study  this 
interesting  and  instructive  instance  that  the  water  became  infected  with 
cholera  germs  through  this  channel.  It  should  be  remembered  that  this 
outbreak  occurred  before  the  days  of  bacteriology,  so  that  direct  proof  is 
not  at  hand.  As  far  as  could  be  determined,  the  infection  of  the  well 
came  from  an  unrecognized  case  of  cholera  in  the  house  at  No.  40  Broad 
Street.  There  were  four  severer  cases  of  cholera  subsequently  in  the 
same  house. 

The  Cholera  Epidemic   in  Hamburg  in   1892. — This  epideni^e, 
31 


ASIATIC   CHOLERA 

AND 

THE  BROAD  STREET  WELL. 

LONDON   I6S4.      

W... .WCLL. 

D MAIN    DRAIN    OF  HOUtC    NQ.40. 

VANOV.t.CCLLARS    UNDER   8TIICCT. 

C ....CESSPOOL. 

P._- PRIVY» 

CftFTCn   Ma  YOR(^  OMCINAL    DRAWINOS.) 


Fig.  115. 


9;30  WATER  AND  l^l'S  KI-^LATION"  TO  DISEASI<: 

stands  out  clearly,  iiot  only  as  one  of.  the  most  devastatijif^  of  modern 
times,  but  as  one  of  the  most  instructive.  The  relation  between  the 
infected  water  and  the  disease  was  conclusively  proven,  and  the  value 
of  slow  sand  filtration  placed  upon  a  strong  foundation.  The  conditions 
of  the  epidemic  were  equal  to  those  of  a  well-controlled  laboratory  ex- 
periment, and  the  bacteriological  and  epidemiological  evidence  corrobo- 
rated each  other  in  every  essential  particular. 

From  August  17  to  October  23,  1892,  a  little  over  two  months,  there 
were  nearly  17,000  cases  of  cholera  in  Hamburg  (population  640,000), 
with  8,605  deaths.  On  one  day  during  the  height  of  the  epidemic  over 
1,000  new  cases  occurred.  This  was  a  pandemic  year  for  cholera  in 
the  sense  that  it  showed  a  remarkable  tendency  to  spread  to  all  parts 
of  the  world.  It  traveled  from  the  valley  of  the  Ganges  through  Per- 
sia, to  Russia,  Germany,  Austria,  France,  Belgium,  Holland,  and  the 
disease  was  brought  to  our  own  doors  and  several  cases  occurred  in 
New  York  City. 

Hamburg  is  a  separate  city,  and  at  the  time  of  the  epidemic  had  a 
population  of  6-40,000.  Altona  (population  143,000)  is  in  Prussia. 
Politically  Hamburg  and  Altona  are  separate,  but  geographically  and 
actually  they  form  one  large  city.  The  boundary  runs  through  a  street 
on  one  side  of  which  is  Hamburg,  on  the  other  Altona.  Wandsbeck 
(population  20,000)  is  a  nearby  suburban  town.  Each  of  these  three 
places  at  the  time  of  the  epidemic  had  a  separate  water  supply.  Wands- 
beck drank  filtered  water  from  a  spring  little  subject  to  pollution. 
Hamburg  and  Altona  were  both  furnished  with  water  from  the  Elbe 
Eiver,  which  is  a  grossly  polluted  stream.  Both  the  cities  of  Hamburg 
and  Altona  rest  upon  the  bank  of  the  Elbe  Eiver,  but  Altona  is  below 
or  downstream.  At  the  time  of  the  epidemic  the  intake  for  the  water 
supply  of  each  city  was  directly  at  the  river  front,  and  the  sewers  of 
the  city  emptied  into  the  river  at  various  points  along  the  same  river 
fronts.  It  will  therefore  be  seen  that  Altona  had  Elbe  Eiver  water  plus 
Hamburg's  sewage.  Altona,  however,  first  filtered  this  water  by  the 
slow  sand  process;  Hamburg,  however,  furnished  its  citizens  with  the 
raw,  unfiltered  Elbe  Eiver  water.  This  water  was  first  pumped  to  a 
single  reservoir,  which  at  one  time  held  approximately  a  day's  supply, 
but  had  long  outgrown  its  usefulness.  It  will  therefore  be  seen  that 
these  three  cities,  with  a  homogeneous  population,  with  the  same  climate, 
the  same  low-lying  site,  and  all  other  conditions  similar,  differed  only 
in  their  water  supply. 

Eelatively  few  cases  occurred  in  Altona,  and  most  of  these  were  on 
the  boundary,  where  the  people  probably  had  access  to  the  raw,  un- 
filtered Elbe  Eiver  water.  In  Koch's  own  words,  "cholera  in  Ham- 
burg went  right  up  to  the  boundary  of  Altona  and  there  stopped. 
In  one  street,  which  for  a  long  way  forms  the  boundary,   there  was 


SPECIFIC  DISEASES  DUE  TO  WATEE 


931 


cholera    on    the    Hamburg    sicle^,    whereas    the    Altoiia    side    was    free 
from  it.'^ 

During  the  epidemic  the  deaths  in  the  several  cities  were  as  follows : 


Population 

Deaths 

Deaths 
per  10,000 
Inhabitants 

Hamburg 

Altona 

Wandsbeck 

640,4C0 

143,000 

20,000 

8,605 

328 

43 

134.4 
23.0 
22.0 

Further  evidence  consisted  in  the  fact  that  at  one  point  close  to 


Fig.  116. — Hamburg  received  its  water  supply  from  the  River  Elbe  (unfiltered)  at  G. 
The  sewage  of  Hamburg  and  Altona  entered  the  Elbe  at  ABC.  Altona  received  its 
water  supply  from  the  Elbe  at  D,  about  8  miles  below  ABC.  The  sand  filters  which 
purified  this  water  were  located  at  Blankenese.  Wandsbeck  had  an  independent  water 
supply  from  a  small  lake. 

and  on  the  Hamburg  side  of  the  boundary  line  between  Hamburg  and 
Altona  is  a  large  yard  known  as  the  Hamburger  Platz.  It  contains 
two  rows  of  large  and  lofty  dwellings  containing  seventy-two  sepa- 
rate tenements  and  some  400  people  belonging  almost  wholly  to  those 
classes  who  suffer  most  from  cholera  elsewhere  in  Hamburg.  While 
cholera  prevailed  all  around  no  single  case  occurred  among  the  many 
residents  of  this  court  during  the  whole  epidemic.  Koch  found  that, 
owing  to  local  diiBculties,  water  from  the  Hamburg  mains  could  not 
easily  be  obtained  for  the  dwellings  in  question,  and  hence  a  supply 
had  been  obtained  from  one  of  the  Altona  mains  in  an  adjacent  street'. 
This  was  the  only  part  of  Hamburg  that  received  Altona  water,  and  it 
was  also  the  only  spot  in  Hamburg  in  which  was  aggregated  a  population 
of  the  class  in  question  which  escaped  the  cholera.  The  source  of  the 
epidemic  was  traced  to  Eussian  immigrants  crowded  in  barracks  on  one 


933  WATEE  AND  ITS  EELATION  TO  DISEASE 

of  the  wharves  pending  their  embarkation  for  the  United  States,  and 
"at  the  time  of  the  outbreak  there  were  on  an  average  about  1,000  of 
these  people  on  hand  all  the  time.  Many  of  them  came  from  districts 
in  Kussia  which  had  been,  and  were  then,  suffering  severely  from 
cholera,  and  all  were  well  supplied  with  dirty  clothing  and  blankets, 
some  of  which  they  washed  while  they  were  being  detained.  It  is  be- 
lieved that  among  those  that  had  arrived  there  must  have  been  some 
mild  cases  of  the  disease,  or  at  least  some  convalescents  with  cholera 
germs  still  in  their  evacuations  two  or  three  weeks  after  recovery.  All 
of  the  sewage  matters  of  every  description  from  these  people  were  dis- 
charged directly  into  the  river  at  the  wharf."  After  the  Elbe  Eiver 
once  became  seeded  with  the  cholera  vibrios  the  people  in  Hamburg  v/ho 
drank  this  infected  water  took  the  disease,  and  their  discharges,  return- 
ing to  the  river,  added  fuel  to  the  flames.  A  vicious  circle  was  thus 
set  up,  so  that  the  infection  became  exceedingly  concentrated  and  in- 
tense, and  as  the  circle  was  a  short  one  the  time  interval  was  corre- 
spondingly brief  and  the  virulence  unusually  severe. 

The  Hamburg  outbreak  will  ever  remain  classic  on  account  of  the 
clearness  of  the  circumstances  and  the  fact  that  there  is  no  inissing 
link  in  the  chain  of  evidence  as  the  specific  organism  was  readily  iso- 
lated from  the  Elbe  Eiver  water. 

Typhoid  Fever. — The  Influence  of  Pure  Water  upon  Typhoid 
Fever. — The  effect  of  an  improved  water  supply  appears  to  have  a 
more  favorable  influence  upon  typhoid  fever  than  upon  any  other  dis- 
ease. The  relation  between  water  and  typhoid  fever  has  long  been 
known,  and  the  attention  of  vital  statisticians  has  been  focused  upon 
the  improvement  in  morbidity  and  mortality  of  this  disease  following 
the  purification  of  a  water  supply.  There  is  now  reason  to  believe 
that  the  good  effects  of  a  pure  water  in  preventing  other  diseases  may 
possibly  outweigh  the  good  effects  in  typhoid  alone.  The  typhoid  figures 
present  such  clear  and  often  dramatic  proof  of  the  value  of  clean  water 
in  the  conservation  of  health  that  a  few  of  the  striking  tables  and  charts 
are  shown  upon  the  following  pages,  and  should  be  carefully  studied 
by  the  student. 

For  the  general  character  of  water-borne  epidemics  of  typhoid  fever 
and  the  relation  of  ice  and  cold  water  to  typhoid  see  page  96. 

The  table  on  page  914,  compiled  by  Kober,^  clearly  shows  the  effect 
of  improving  the  water  supply  in  typhoid  fever  death  rates  in  American 
cities. 

From  this  table  we  learn  that  the  combined  average  annual  rate 
from  typhoid  fever  in  cities  with  a  polluted  supply  was  69.4,  and  after 
the  substitution  of  a  purer  water  fell  to  19.8  per  100,000 — a  reduction 

'"Conservation  of  Life  and  Health  by  Improved  Wafer  Supply,"  George  M. 
Kober,   1908. 


SPECIFIC  DISEASES  DUE  TO  WATER 


93^ 


of  70.5  per  cent.  The  Bulletin  of  the  New  York  State  Health  Depart- 
ment for  April,  1908,  shows  that  the  death  rate  from .  typhoid  fever 
in  ten  cities  of  that  state  has  been  reduced  53.4  per  cent,  by  an  im- 
proved water  supply.    Many  similar  instances  are  cited  in  the  literature. 


Table  showing  the  average  typhoid  death  rate  per  100,000  for  a  period  prior  to  the  improve- 
ment in  the  water  supply,  the  average  typhoid  death  rate  per  100,000  since  the  change 
in  the  water  supply,  and  the  percentage  of  reduction  caused  by  the  improvement 


Place 

Average 

Before 

Improvement 

Average 

After 

Improvement 

Per  Cent. 
Reduction  in 
Death  Rate 

1 

Albany 

88.8 
39.3 
54.9 
42.2 
64.3 
67.2 
95.5 
25.0 
58.2 
94.7 

23.7 
11.7 
41.5 
24.7 
31.9 
14.6 
54.4 
14.4 
31.0 
36.9 

73.0 

9 

Binghamton 

72.2 

3 

Elmira 

24.4 

4 

Hornell 

41.4 

5 

Hudson 

50.5 

6 

Ithaca 

78.3 

7 

Rensselaer 

43.0 

8 

Schenectady 

42.6 

q 

Troy 

46.8 

10 

Watertown 

61.8 

The  Typhoid  Epidemic  at  Lausen"^  Switzerland. — The  epidemic 
of  typhoid  fever  which  occurred  in  Lausen,  Switzerland,  in  1872,  was 
the  first  to  attract  general  attention,  "and,  because  of  certain  peculiar 
conditions  connected  with  it,  and  especially  because  of  its  influence  upon 
the  theory  and  practice  of  the  purification  of  water  by  filtration,  it  de- 
serves the  most  careful  consideration  by  all  students  of  sanitation." 
It  is  also  interesting  because  of  the  remoteness  and  unusual  method 
by  which  the  infection  reached  the  water  supply.  The  following  ac- 
count of  this  epidemic  is  from  the  description  by  Sedgwick,  quoting 
Dr.  Hagler's  ^  report : 

The  epidemic  occurred  in  the  little  village  of  Lausen  in  the  canton 
of  Basel  in  Switzerland  in  August,  1872.  Lausen  was  a  well-kept  village 
of  90  houses  and  780  inhabitants,  and  had  never,  so  far  as  known,  suf- 
fered from  a  typhoid  epidemic.  Eor  many  years  it  had  not  had  even 
a  single  case  of  typhoid  fever,  and  it  had  escaped  cholera  even  when  the 
surrounding  country,  suffered  from  it.  Suddenly,  in  August,  1872,  an 
outbreak  of  typhoid  fever  occurred,  affecting  a  large  part  of  the  entire 
population. 

A  short  distance  south  of  Lausen  is  a  little  valley,  the  Fiirlerthal, 
separated  from  Lausen  by  a  hill,  the  Stockhalden,  and  in  this  valley,  on 
June  19,  upon  an  isolated  farm,  a  peasant,  who  had  recently  been  away 
from  home,  fell  ill  with  a  very  severe  case  of  typhoid  fever,  which  he 
had  apparently  contracted  during  his  absence.     In  the  next  two  months 

^  Sixth  Report,  Rivers  Pollution   Comm,ission  of  1868,  London,   1874. 


1880 


Fig.  117. — Change  in  Water  Supply. 

1. — From  unfiltered  river  supply  to  filtered  river  supply. 
2. — From  unfiltered  river  supply  to  wells. 
3. — From  polluted  river  supply  to  conserved  river  supply. 
934 


(Kober.) 


jo       10       20      30      40      50      <iO      70     80       90      100     IIO     120 

Pure  Mounlmn  Springs 

Munich 
Vieiiiiii 
Berlin 

ZUTRll 
IHiUUlllltQ 

__ 

_ 

__ 

__ 





40 

■  ' 

— 

■■ — 

Filtered  Waters 
European  fHics 

— 

— 

— 

— 

a 

■ 

0.6 

Paris 

■■ 

___ 

Lfliidoii 
f  ^itmou 
Biii()liuiiit(iii 
Alhiiiiu 
ixiwrtnte 
Iwalertuwii 
Riiliinondlmrduyh 
Qtieenslioruiiuh. 
Camden 
Lowell 
Filclrtwra 
CamhruKie 
SonwrviUt 
VWarcfester 

Maiden 

Boston 

Chelsea. 

New  Bedford 

Waterbtiru 

Holijoke 

Bro)ixborouQli 

MantiatlaiitHifoiinh 

Pawtutket 

Newark 

Rochester 

Brocton 

Taunton 

HaverhrtI 

Portland 

Salem 

MttwauKee 

Detroit 

Chictioo 

ir"r 

Qevcland 

Dululh 

StPaul 

Canton 

BrooM«nl)orou()h 

Coluinous 

McKeesport 

K/iiuueanulis 

Seattle 

NewOrteans 

Toledo 

EvansviHe 

Springfield 

CoYinQlon 

GrenOapids 

Wilmingion 

Richmond 

Cincinnati 

LouisviUe 

Philadelpliia 

Lancaslfr 

Atlanta 

^arrtsl)ur9 

Wheeling  " 

Alleghenu 

H 

' 

1  1 

Frttercd  Waters 
American  Cilies 

■■■ 

— 

162 

aaa 

1 

88 

1 

1 

~~ 

I 

GroundWalers- large  vvells 

'■■' 

— 18.1 

— 

1 

gg- 

ImpouTiding  Reservoirs 
Protected  Water  sheds 

■■■^1 

~18.5 

1 

1 

■IBi^H 

1., 

8 

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Protected  Piver  or  Stream  supply 

1       1      1       r      1       1      1  '    1 1 

18.5 

B           F^H 

H 

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SmallLaKes 

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B       am 

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Great  Lakes  subject  to  pollution 

— 









-33.1 

a 

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- 

— 

— 

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— 

— 

— 

l_ 

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Mixed  surface  and  underground  waters 

— 1 — 1 — 1 — 1 — 1 — 1 — 1 — 1 — i — I — 1 — 1 — 

m- 

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BEBBaBSBSBS^ 

H 

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Bl 

^nsn*.™ 

Fig.  118. — Mean  Death  Rates  from  Typhoid  Fever,  1902  to  1906,  in  66  American 
Cities  and  7  Foreign  Cities  Grouped  According  to  their  Drinking  Water. 
The  rates  for  foreign  cities  are  taken  from  James  H.  Fuertes.  (Kober.) 


935 


936  WATER  AND  ITS  RELATION  TO  DISEASE 

there  occnrrecT  three  other  cases  in  the  neighhorhood — a  ;^irl,  and  the 
wife  and  son  of  the  peasant. 

No  one  in  Laiisen  knew  anything  of  these  cases  in  tlie  remote  and 
lonely  valley,  when  suddenly,  on  August  7,  ten  cases  of  typlioid  fever 
appeared  in  Lausen,  and  by  the  end  of  9  days  57  cases.  The  number 
rose  in  the  first  four  weeks  to  more  than  one  hundred,  and  by  the  end 
of  the  epidemic  in  October  to  about  130,  or  seventeen  per  cent,  of  the 
population.  Besides  these,  fourteen  children  who  had  spent  their  sum- 
mer vacation  in  Lausen  fell  ill  with  the  same  disease  in  Basel.  The 
fever  was  distributed  quite  evenly  throughout  the  town,  with  the  excep- 
tion of  certain  houses  which  derived  their  water  from  their  own  wells 
and  not  from  the  public  water  supply.  Attention  was  thus  fixed  upon 
the  latter,  which  was  obtained  from  a  well  at  the  foot  of  the  Stockhalden 
hill  on  the  Lausen  side.  The  well  was  walled  up,  covered,  and  appar- 
ently protected,  and  from  it  the  water  M^as  conducted  to  the  village, 
where  it  was  distributed  by  several  public  fountains.  Only  six  houses 
used  their  own  wells,  and  in  these  six  there  was  not  a  single  case  of 
typhoid  fever,  while  in  almost  all  the  other  houses  of  the  village,  which 
depended  upon  the  public  water  supply,  cases  of  the  disease  existed. 
Suspicion  was  thus  directed  to  the  water  supply  as  the  source  of  the 
typhoid,  very  largely  because  no  other  source  could  well  be  imagined. 

There  had  long  been  a  belief  that  the  Lausen  well  or  spring  was 
fed  by  and  had  a  subterranean  connection  with  a  brook  (the  Fiirler 
brook)  in  the  neighboring  Eiirler  valley;  and  since  this  brook  ran  near 
the  peasant's  house  and  was  known  to  have  been  freely  polluted  by  the 
excreta  of  the  typhoid  fever  patients,  absolute  proofs  of  the  connection 
between  the  wall  of  Lausen  and  the  Fiirler  brook  could  not  fail  to  be 
highly  suggestive  and  important.  Fortunately,  such  proofs  were  not 
far  to  seek.  Some  ten  years  before  observations  had  been  made  which 
had  shown  an  intimate  connection  between  the  brook  and  the  well. 
At  that  time,  without  any  known  reason,  there  had  suddenly  appeared 
near  the  brook  in  the  Fiirler  valley  below  the  hamlet  a  hole  about  eight 
feet  deep  and  three  feet  in  diameter,  at  the  bottom  of  which  a  consider- 
able quantity  of  clear  water  was  flowing.  As  an  experiment  the  water 
of  the  little  Fiirler  brook  was  at  that  time  turned  into  this  hole,  with 
the  result  that  it  had  all  flowed  away  underground  and  disappeared,  and 
an  hour  or  two  later  the  public  fountains  of  Lausen,  which,  on  account 
of  the  dry  weather  prevailing  at  the  time,  were  not  running,  had  begun 
flowing  abundantly.  The  water  from  them,  which  was  at  first  turbid, 
later  became  clear;  and  they  had  continued  to  flow  freely  until  the 
Fiirler  brook  was  returned  to  its  original  bed  and  the  hole  had  been 
filled  up.  But  every  year  afterward,  whenever  the  meadows  below  the 
site  of  the  hole  were  irrigated  or  overflowed  by  the  waters  of  the  brook, 
the  Lausen  fountains  soon  began  to  flow  more  freely.     In  the  epidemic 


SPECIFIC  DISEASES  DUE  TO  WATEE  937 

year  (1872)  the  meadows  had  been  overflowed  as  usual  from  the  middle 
to  the  end  of  July,  which  was  the  very  time  when  the  brook  had  been 
infected  by  the  excrements  of  the  typhoid  patients.  The  water  supply 
of  Lausen  had  increased  as  usual,  had  been  turbid  at  the  beginning,  and 
had  had  a  disagreeable  taste.  And  about  three  weeks  before  the  begin- 
ning of  the  irrigation  of  the  Flirler  meadows  typhoid  fever  had  broken 
out,  suddenly  and  violently,  in  Lausen. 

In  order  to  make  matters,  if  possible,  more  certain  the  following 
experiments  were  made,  but  unfortunately  not  until  the  end  of  August 
when  the  water  of  the  Lausen  supply  had  again  become  clear.  The  hole 
which  had  appeared  ten  years  earlier,  and  had  afterward  been  filled  up, 
was  reopened,  and  the  little  brook  was  once  more  led  into  it ;  three  hours 
later  the  Lausen  fountains  were  yielding  double  their  usual  volume.  A 
quantity  of  brine  containing  about  eighteen  hundred  pounds  of  common 
salt  was  now  poured  into  the  brook  as  it  entered  the  hole,  whereupon 
there  appeared  very  soon  in  the  Lausen  water  first  a  small,  later  a  con- 
siderable, and  finally  a  very  strong  reaction  for  chlorin,  while  the  total 
solids  increased  to  an  amount  three  times  as  great  as  before  the  brine 
was  added.  In  another  experiment  five  thousand  pounds  of  flour 
(Mehl),  finely  ground,  were  likewise  added  to  the  brook  as  it  disap- 
peared in  the  hole;  but  this  time  there  was  no  increase  of  the  total 
solids,  nor  were  any  starch  grains  detected  in  the  Lausen  water. 

It  was  naturally  concluded  from  these  experiments  that  while  the 
water  of  the  brook  undoubtedly  passed  through  to  Lausen  and  carried 
with  it  salts  in  solution,  it  nevertheless  underwent  a  filtration  which 
forbade  the  passage  of  suspended  matters  as  large  as  starch  grains.  Dr. 
Hagler,  from  whose  report  the  foregoing  facts  are  taken,  was  careful, 
however,  to  state  that  "it  is  not  denied  that  small  organized  particles, 
such  as  typhoid  fever  germs,  may  nevertheless  have  been  able  to  find  a 
passage."  As  a  matter  of  fact  Dr.  Hagler's  minute  account  does  to-day 
give  us  some  indication  that  such  germs  might  easily  have  passed  from 
the  brook  to  Lausen,  for  the  turbidity  of  which  he  repeatedly  speaks  is 
evidence  of  the  passage  of  particles  as  small  as,  and  possibly  smaller 
than,  the  germs  of  typhoid  fever.^ 

Unfortunately  this  was  before  pure  cultures  of  bacteria  were  known, 
and  no  experiments  were  made  v/ith  suspended  matters  as  small  as  bac- 
teria. The  conclusion  was  inevitable  that  although  filtration  had  in  this 
case  sufficed  to  remove  starch  grains,  it  had  been  powerless  to  remove  the 
germs  of  typhoid  fever;  and,  accordingly,  filtration  as  a  safeguard 
against  disease  in  drinking  water  fell  for  a  time  into  disrepute.^ 

^  "Typhus  und  Trinkwasser,"  Vierteljahresschrift  fur  offentlicJie  Gesund- 
heitspflege,  VI,  154;  also  Sixth  Report,  Rivers  Pollution  Commission  of  1868, 
London,   1874. 

^Sedgwick,  Journal  'New  England  Water  Works  Association,  XV,  1901,  p. 
330,  No.   4. 


938 


WATER  AND  ITS  RELATION  TO  DISEASE 


4T!!  RESERVOIR 


House  FROM  WHICH 
'^THE  INFECTION  CAMS . 

/OlH 


The  Typhoid  Eimdemic  in  Plymouth,  Penn. —  In  1885  the  mining 
town  of  Plymouth,  Penn.,  with  a  population  of  about  8,000,  suffered 
with  a  severe  outbreak  of  typhoid  fever  which  involved  one  in  every 
eight  of  the  inhabitants.  Plymouth  received  its  water  from  a  mountain 
brook  which  drained  an  almost  uninhabited  watershed.  The  stream 
was  dammed  at  intervals  and  the  water  was  stored  in  a  series  of  four 
small  impounding  reservoirs.     The  source  of  the  infection  was  traced 

to  a  citizen  who  spent  his 
Christmas  holidays  in  Phil- 
adelphia and  returned  home 
in  January.  He  contracted 
typhoid;  the  excreta  were 
not  disinfected,  but  were 
thrown  either  into  the 
frozen  creek  or  upon  its 
banks  within  25  or  30  feet 
of  the  edge  of  the  stream. 
(See  map.)  At  this  time 
the  hrook  was  frozen  and 
remained  so  until  spring. 
There  came  a  thaw  in 
March  and  the  entire  accu- 
mulation was  washed  into 
the  brook  and  thence  into 
the  water-main.  Three 
weeks  thereafter  cases  of  ty- 
phoid by  the  score  made 
their  appearance  throughout 
the  town.  On  some  days 
more  than  100  new  cases  oc- 
curred. In  all  1,004  cases 
were  reported.  Some  esti- 
mates placed  the  number  at 
1,500,  that  is,  1  in  every  5  of  the  inhabitants.  There  were  114  deaths. 
The  epidemic  was  limited  to  the  houses  supplied  with  the  town  water  or 
to  persons  who  drank  of  the  public  water  supply.  The  distinction  was 
particularly  emphasized  on  one  street  where  the  houses  on  one  side  had 
one  or  more  cases  while  the  houses  on  the  other  side  had  none  at  all. 
The  former  were  supplied  by  the  town  water,  the  latter  depended  upon 
wells. 

This  epidemic  will  ever  stand  out  in  the  literature  as  a  clear-cut 
instance  of  water-borne  typhoid  caused  by  the  quick  transfer  of  virulent 
material  from  a  single  case.  It  proves  further  that  freezing  alone  was 
not  sufficient  to  destroy  the  typhoid  infection,  and  on  account  of  the 


MAP  OF 

PLYMOUTH,  PENN» 

IN     1865. 


Fig.  119. 


SPECIFIC  DISEASES  DUE  TO  WATER  939 

coldness  of  the  water  it  is  exceedingly  unlikely  that  any  multiplication 
of  the  typhoid  bacilli  occurred.  The  infection,  although  greatly  diluted, 
was  nevertheless  sufficiently  virulent  to  induce  the  disease  in  most  of 
those  who  drank  the  water.  It  further  teaches  the  lesson  how  one  per- 
son is  sufficient  to  defile  the  "pure  waters  of  a  mountain  brook  draining 
an  almost  uninhabited  territory."  This  epidemic  was  the  first  large 
outbreak  in  America  where  the  cause  was  definitely  traced  to  the  water 
supply.  It  stands  out  sharply  in  the  sanitary  annals  of  our  country  on 
account  of  the  lessons  it  taught  and  the  good  influence  it  had  in  stimu- 
lating other  cities  to  safeguard  and  improve  their  water  supplies. 

The  Typhoid  Epidemic  at  New  Haven. — Very  similar  to  the  Plym- 
outh outbreak  was  that  at  New  Haven,  Conn.,  during  April,  May,  and 
June  of  1901,  when  514  cases  of  typhoid  fever  occurred,  resulting  in  73 
deaths.  The  outbreak  was  carefully  studied  by  Professor  Herbert  E. 
Smith,  who  found  that  it  was  unquestionably  due  to  an  infection  of  one 
of  the  sources  of  public  water  supply. 

The  water  supply  in  New  Haven  was  drawn  from  five  distinct  sys- 
tems. It  was  all  surface  water  and  was  used  without  filtration.  One  of 
the  sources  was  known  as  the  Dawson  supply.  Dawson  Lake  was  a 
storage  reservoir  located  on  "West  River  in  Woodbridge,  five  miles  from 
New  Haven.  Dawson  Lake  had  an  area  of  60  acres  and  a  capacity 
of  300,000,000  gallons.  There  was  no  direct  sewage  pollution  upon 
the  catchment  area  and  the  rural  population  was  only  25  per  square 
mile. 

A  mile  and  a  half  above  the  Dawson  Lake  a  small  stream  flowed  into 
the  river,  and  about  half  a  mile  up  this  stream  there  was  a  farmhouse 
situated  at  an  elevation  of  about  180  feet  above  the  water  in  the  lake. 
Several  cases  occurred  in  this  house  during  January  and  February,  1901. 
The  excreta  was  thrown  into  a  shallow  privy  vault  without  disinfection 
(for  the  reason  that  typhoid  fever  was  not  at  first  recognized).  Here 
they  accumulated  and  remained  more  or  less  frozen  for  six  weeks  or 
more.  This  privy  was  325  feet  from  the  brook  and  40  feet  above  it. 
On  March  10  and  11  there  were  a  heavy  rainfall  (2.46  inches)  and  a 
sudden  thaw.  The  flow  was  so  large  that  in  spite  of  the  intervention 
of  the  storage  reservoir  the  water  in  the  city  was  in  a  turbid  condition 
on  the  afternoon  of  March  11.  The  typhoid  fever  outbreak  began  about 
10  days  later,  and  fhere  seems  to  be  little  doubt  that  infection  took 
place  at  this  time.  Professor  Smith  found  that  96  per  cent,  of  the  cases 
that  occurred  were  in  the  districts  supplied  with  water  from  the  Dawson 
Lake.      (Whipple.) 

This  outbreak  again  illustrates  the  resistance  of  the  typhoid  infection 
to  freezing,  and  the  danger  from  a  surface  supply  that  for  years  may  run 
satisfactorily.  Even  the  storage  reservoir  failed  in  this  case,  as  in  the 
Plymouth  case,  to  check  the  quick  transfer  of  the  infection.     Had  the 


940 


WATER  AND  ITS  RELATION  TO  DISEASE 


Dawson  supply  been  filtered  or  otliervvise  purified  the  epidemic  could 
have  been  averted. 

The  Typhoid  Epidemic  at  Ashland,  Wisconsin. — This  outbreak 
is  cited  from  Harrington  and  is  one  of  peculiar  interest,  in  that,  in 
addition  to  serving  as  an  excellent  illustration  of  the  danger  of  using 
the  same  body  of  water  as  a  place  for  the  disposal  of  sewage  and  as  a 
source  of  drinking  water,  it  Avas  made  the  basis  of  an  action  at  law, 
which  established  the  lialjility  of  water  companies  and  municipalities 


Fig.  120. 


in  case  of  sickness  and  death  caused  by  the  distribution  and  use  of 
infected  water. 

The  city's  supply  is  derived  from  an  arm  of  Lake  Superior,  Che- 
quamegon  Bay,  upon  which  the  city  is  situated.  This  bay,  which  is 
about  twelve  miles  long,  and  of  an  average  width  of  five,  varies  from 
eight  to  thirty-six  feet  in  depth.  North  of  the  city,  and  extending  out- 
ward in  a  northwestwardly  direction,  is  a  breakwater  constructed  for  the 
protection  of  the  harbor  against  northerly  gales ;  and  between  it  and  the 
city  the  mouth  of  the  water  intake  is  located  about  a  mile  from  the 
shore.  (See  Fig.  120.)  The  sewage  of  the  city  is  discharged  further  to 
the  west  and  south.  The  currents  in  the  bay  follow  the  course  indicated 
by  the  arrows  in  the  figure,  and  carry  the  sewage  toward  the  breakAvater 
and  over  the  mouth  of  the  intake.    This  condition  of  affairs  was  brought 


SPECIFIC  DISEASES  DUE  TO  WATER  941 

to  the  attention  of  the  company  by  the  health  boards  of  the  city  and 
state  repeatedly,  but  without  results.  That  the  water  was  polluted  was 
evident  on  mere. ocular  inspection,  for  it  was  often  cloudy  or  markedly 
turbulent.  During  the  winter  of  1893-94  typhoid  fever  made  its  ap- 
pearance in  the  city,  and  from  the  initial  cases  a  disastrous  epidemic  de- 
veloped, which  led  to  the  establishment  of  a  model  filtering  plant. 

.  The  action  at  law  referred  to  above  was  brought  by  the  widow  of 
one  of  the  victims.  In  evidence  it  was  shown  that  he  lived  continuously 
in  Ashland,  and  drank  no  water  other  than  that  supplied  by  the  water 
company;  that  previous  to  his  seizure  the  disease  had  prevailed  in  the 
city,  and  that  the  discharges  from  the  antecedent  cases  had  passed  into 
the  waters  of  the  bay  by  way  of  the  city  seAvers.  The  court  found  for 
the  plaintiff  in  the  sum  of  $5,000. 

The  Typhoid  Epidemic  in  Mankato,  Minn. — Mankato  (popula- 
tion 11,553)  receives  its  ^oater  supply  from  four  deep  artesian  wells  on 
Washington  Street.  Two  of  these  wells  are  within  from  16  to  18  feet 
of  the  pumping  station.  The  main  outlet  of  the  sewer  runs  down  Wash- 
ington Street,  emptying  into  the  river.  A  great  flood  occurred  May  20 
to  34,  1908.  The  gate  in  the  main  trunk  of  the  sewer  was  let  down  on 
the  night  of  June  24,  1908,  in  order  to  keep  the  river  from  backing  up 
into  the  sewers.  This  caused  a  backing  up  or  stasis  of  the  sewage,  which 
in  turn  backed  up  into  a  well  pit  of  the  new  artesian  well  near  the 
pumping  station,  hence  sewage  was  pumped  into  the  water  system.  Two 
of  the  other  wells  and  -suction  mains  were  rusty  and  leaked  and  had 
not  been  properly  looked  after  for  a  number  of  years.  Then  came  a 
sudden  sharp  epidemic  of  diarrhea,  June  26.  Probably  2,000  persons 
were  affected.  It  soon  developed  that  the  prevailing  disease  was  typhoid 
fever.  The  epidemic  lasted  from  June  26  and  gradually  died  out  by 
Nov.  20,  1908.  From  July  7  to  Nov.  20  464  cases  of  typhoid  fever 
were  reported  to  the  Health  Officer.  Four  hundred  and  one  of  these 
cases  were  considered  primary  and  57  secondary  or  contact  cases  and  6 
outside  or  imported  infection. 

This  water-borne  outbreak  of  typhoid  fever  is  particularly  instructive 
from  the  fact  that  Delia  McKeever  and  Kate  Flanagan,  administratrices 
of  the  estates  of  their  husbands,  who  had  died  of  the  fever,  sued  the  city 
of  Mankato  for  damages.  The  city  demurred  to  this  complaint  on  the 
grounds  that  as  a  government  it  could  not  be  sued  and  was  exempt 
because  it  was  carrying  out  a  government  function.  The  Supreme  Court 
of  Minnesota  held  that  "the  state  is  liable  if  damages  can  be  proved." 
The  decision  of  the  Supreme  Court  in  holding  the  city  liable  sets  an  ex- 
cellent precedent  which  places  the  responsibility  where  it  should  be. 
Citizens  are  evidently  as  much  entitled  to  reasonable  sanitary  protection 
as  they  are  to  police  protection,  or  to  protection  from  accidents  at  grade 
crossings.    It  is  a  fortunate  day  for  preventive  medicine  when  the  prin- 


943  WATER  AND  ITS  RELATION  TO  DISEASE 

eiple  is  recognized  tliat  sanitary  negligence  is  jnst  as  culjmhle  as  the 
negligence  wliich  fails  to  place  a  red  flag  or  a  red  lantern  to  warn 
against  a  pitfall  in  the  public  highway. 

TpiE  Typhoid  Epidemic  in  Ittiaca,  New  Yokk. — Li  the  winter  of 
1903  Ithaca,  New  York,  the  seat  of  Cornell  University,  was  visited  by  a 
severe  epidemic  in  the  course  of  which  1,350  cases  of  typhoid  fever 
occurred  in  a  population  of  about  13,156.  The  population  included 
about  3,000  students  at  the  university.  More  than  500  homes  were  vis- 
ited and  there  were  83  deaths.  The  epidemic  covered  a  period  of  about 
3  months  and  extended  from  about  the  11th  of  January,  1903,  to  the  1st 
of  April,  although  for  several  months  before  the  epidemic  began  typhoid 
fever  had  been  unduly  prevalent.  The  epidemic  was  carefully  studied 
by  Dr.  George  A.  Soper,  who  clearly  showed  that  the  disease  was  due 
to  the  public  water  supply,  although  the  original  case  or  cases  which 
gave  rise  to  the  epidemic  were  not  ascertained.  Ithaca  had  at  that  time 
three  separate  sources  of  water  supply.  The  larger  one  was  derived 
from  Six-Mile  Creek  and  the  second  supply  from  Buttermilk  Creek,  and 
the  third  was  an  independent  supply  for  the  university.  The  conditions 
on  the  two  streams  were  similar.  Both  streams  were  considerably  pol- 
luted by  the  population  which  lived  largely  in  villages  bordering  on  the 
streams.  The  nearest  of  these  villages  was  5  miles  above  the  intake. 
Soper  found  numerous  other  sources  of  contamination  on  the  water- 
shed, and  some  even  in  the  city  of  Ithaca  a  few  rods  above  the  intake  of 
the  water-works  where  there  were  no  less  than '17  privies  located  on  the 
precipitous  banks  of  the  creek.  It  was  known  that  during  the  year 
previous  to  the  epidemic  there  had  been  at  least  6  cases  of  typhoid  fever 
on  the  watershed.  The  typhoid  epidemic  in  Ithaca  followed  a  flood  in 
the  river. 

One  episode  of  the  epidemic  is  worthy  of  special  mention,  namely, 
a  secondary  outbreak  which  resulted  from  the  infection  of  a  well.  This 
well  had  become  popular  among  the  residents  of  a  certain  district  at  tlie 
time  when  the  public  supply  came  to  be  distrusted,  and  its  good  quality 
was  taken  for  granted.  But  the  wife  of  the  owner  was  taken  sick  with 
typhoid  fever  during  the  epidemic,  and  her  dejecta  passed  without  disin- 
fection through  the  water-closet,  and  into  a  drain-pipe  which  ran  within 
three  or  four  feet  of  the  well.  The  joints  of  the  drain-pipe  were  insecure ; 
and  the  well  water,  which  had  probably  been  for  some  time  grossly 
contaminated,  finally  became  infected.  As  a  result  about  fifty  cases  of 
typhoid  fever  and  five  deaths  were  traced  to  people  who  used  this  well 
water.     (Whipple.) 

The  Typhoid  Epidemic  in  Butlee,  Penn. — Butler,  Penn.  (popu- 
lation 16,000),  had  an  epidemic  of  typhoid  fever  in  1903.  There  were 
1,270  cases,  that  is,  about  8  per  cent,  of  the  population  were  attacked. 
Infection  in  this  case  was  clearly  water-borne  and  was  traced  to  one  of 


SPECIFIC  DISEASES  DUE  TO  WATER  943 

various  points  of  the  stream,  small  tributaries,  or  creeks.  One  house  in 
particular,  provided  with  an  overhanging  privy,  emptied  into  the  creek 
within  a  short  distance  of  the  pumping  station. 

The  Typhoid  Epidemics  of  Lawrence  and  Lowell. — During  the 
years  1890-91  a  typhoid  fever  epidemic  occurred  in  Lowell  and  Law- 
rence, Mass.  This  epidemic  illustrates  with  great  clearness  what  occurs 
on  streams  which  are  used  both  as  sources  of  water  supply  and  as  re- 
ceptacles for  sewage.  Both  cities  are  on  the  Merrimac  Eiver,  which  was 
grossly  polluted  by  the  sewage  of  Manchester  (population  44,126), 
Haverhill  (population  27,412),  Nashua  (population  19,311),  Concord 
(population  17,004),  Fitchburg  (population  22,037),  Newburyport 
(population  13,947),  Marlborough  (population  13,805),  Clinton  (popu- 
lation 10,424),  and  from  other  sources  of  pollution.  In  Lowell  550 
cases  of  typhoid  fever  occurred  from  Sept.,  1890,  to  Jan.,  1891.  The 
epidemic  was  carefully  studied  by  Professor  William  T.  Sedgwick,  who 
made  a  most  thorough  investigation. 

A  short  time  after  the  epidemic  in  Lowell  typhoid  fever  broke  out 
in  Lawrence,  nine  miles  downstream,  and  rapidly  increased.  The  rela- 
tion between  these  two  epidemics  was  most  striking.  Lowell  discharged 
its  sewage  into  the  river,  Lawrence  drank  the  water  without  filtration. 
The  climax  of  the  Lawrence  epidemic  occurred  about  one  month  after 
that  in  Lowell.  In  1892  there  was  a  repetition  of  this  episode.  Typhoid 
fever  in  Lowell  was  again  responsible  for  an  increase  of  typhoid  fever 
in  Lawrence.  As  a  consequence  of  these  occurrences  Lowell  abandoned 
the  river  and  introduced  a  ground  water  supply,  while  at  Lawrence  a 
filtration  plant  was  constructed  which  has  materially  reduced  the 
amount  of  typhoid  fever  in  that  city.     (Whipple.) 

The  Typhoid  Epidemics  of  Pittsburgh  and  Alleghany. — These 
two  Pennsylvania  cities  are  situated  at  the  junction  of  the  Alleghany 
and  Monongahela  Elvers,  where  they  unite  to  form  the  Ohio.  In  1900 
Pittsburgh  had  a  population  of  321,616  and  Alleghany  129,896.  Pitts- 
burgh takes  its  water  from  the  Alleghany  Eiver  at  Brilliant  Station,  six 
miles  above  the  junction  of  the  rivers,  and  from  the  Monongahela  Eiver 
at  a  point  three  miles  above  the  junction.  Alleghany  receives  its  water 
supply  from  the  Alleghany  Eiver  at  Montrose,  ten  miles  from  the  point ; 
it  is  drawn  from  a  rock-filled  crib.  It  is  practically  unfiltered  water. 
Both  the  Monongahela  and  the  Alleghany  Elvers  are  grossly  polluted 
streams,  receiving  the  sewage  from  a  populous  watershed;  in  addition 
the  sewers  of  the  cities  of  Alleghany  and  Pittsburgh  empty  directly  into 
these  streams,  and  on  account  of  the  rapid  growth  of  these  cities  much 
of  this  sewage  entered  the  river  dangerously  near  to  the  water  intakes. 
The  records  of  the  Board  of  Health  show  that  at  this  time  there  oc- 
curred annually  upward  of  5,000  cases  of  typhoid  fever. 

For  about  ten  years  centering  around  1900  Pittsburgh  and  Alleghany 


dU  WATEPt  Ai\_U  ITS  EELATIOI^  TO  DISEASE 

bad  the  unenviable  distinction  of  liaving  the  highest  typlioid  death 
rate  of  any  city  in  this  country  and  probably  of  any  large  city  in  tlie 
world.  At  times  the  rates  ran  above  150  per  100^000.  The  condi- 
tions have  recently  been  improved  by  the  introduction  of  slow  sand 
filtration  for  the  city  of  Pittsburgh.  Alleghany,  now  officially  known 
as  North  Pittsburgh,  is  just  being  furnished  (1912)  with  filtered 
water. 

The  Typhoid  Epidemic  at  Chicago. — The  Chicago  epidemic  is  an 
illustration  of  a  city  using  a  lake  water  which  is  infected  with  its  own 
sewage.  The  water  in  1892  was  taken  from  Lake  Michigan  opposite  the 
city  at  several  "cribs"  which  were  1.5  to  4  miles  off-shore.  The  Chicago 
sewage  was  discharged  all  along  the  water-front,  while  the  Chicago  Elver 
penetrated  the  city  with  its  north  and  south  branches  and,  polluted 
almost  beyond  endurance,  flowed  out  into  the  lake  about  midway  be- 
tween the  upper  and  lower  cribs.  The  pollution  of  the  lake  water  was 
at  times  so  intense  that  the  foul  river  water  could  be  traced  to  the  in- 
takes with  the  eye.  This  intolerable  situation  resulted  in  the  building 
of  the  Chicago  drainage  canal,  the  object  of  which  was  to  keep  the 
sewage  out  of  the  lake  and  carry  it  down  the  Des  Plaines  and  Illinois 
Eivers  into  the  Mississippi.  By  the  construction  of  this  canal  the  flow 
of  the  Chicago  Eiver  was  reversed  so  that,  instead  of  the  sewage  entering 
the  lake  and  polluting  the  water  supply,  the  water  of  Lake  Michigan 
now  flows  westward  to  the  Mississippi  and  to  the  Gulf  of  Mexico.  Dur- 
ing the  years  1890,  1891,  and  1892  typhoid  fever  was  unusually  preva- 
lent in  Chicago.  In  1890,  1,008  of  the  inhabitants  died  from  typhoid 
fever,  in  1891  the  death  toll  from  this  preventable  disease  was  997  and 
in  1892  1,489.  The  present  conditions  in  Chicago,  owing  to  the  improve- 
ments in  the  water  supply,  in  the  milk  supply,  and  an  attack  upon  the 
residual  typhoid  as  contact  infection,  have  reduced  the  death  rate  to 
about  12  per  100,000,  which  is  now  among  the  lowest  death  rates  from 
typhoid  fever  in  any  large  city  in  this  country,  and  compares  favorably 
with  some  of  the  European  figures. 

The  above  water-borne  typhoid  fever  epidemics  have  been  selected 
as  examples.  Many  more  may  be  found  in  the  literature.  Whipple,  in 
his  book  on  "^"^Typhoid  Fever,"  cites  numerous  instances  and  gives  in 
•[tabular  form  an  impressive  list  of  such  outbreaks,  with  references  to 
-the  iiterature. 

;I>yseiiit,ery,.^ — Both  bacillary  dysentery  and  amebic  dysentery  may  be 
ftransf erred  throvigh  -drinking  water.  The  infection  in  both  types  of 
.dysentery  is  discharged  in  the  feces  and  taken  in  by  the  mouth;  there 
is,  therefore,  every  opportunity  for  water  to  play  the  same  role  in  dysen- 
tery that  it  plays  in  typhoid.  However,  comparatively  few  water-borne 
epidemics  of  bacillary  dysentery  have  been  reported ;  these  few,  neverthe- 
less, are  sufficiently  conclusive  to  be  convincing.    Amebic  dysentery  does 


SPECIFIC  DISEASES  DUE  TO  WATEE  945 

not  occur  in  epidemic  form,  but  the  known  facts  are  sufficient  to  in- 
criminate water  as  one  of  the  vehicles  of  convection. 

Shiga  reports  outbreaks  in  Japan  from  the  use  of  well  and  river' 
water.  Eldridge  states  that  dysentery  is  a  rural  disease  in  Japan;  the 
use  of  human  feces  as  a  fertilizer  and  the  frequency  of  the  infection  of 
the  numerous  small  streams  and  wells  render  it  preeminently  a  water- " 
borne  disease.  Whittaker  ^  reports  a  water-borne  epidemic  of  dysentery 
at  South  St.  Paul,  Minnesota,  caused  by  using  infected  water  from  a 
fire  connection.  The  epidemic  described  by  Duprey  which  occurred  at 
Grenada  Island  in  1901  is  one  of  the  best  examples  of  a  water-borne 
epidemic  of  dysentery.  Shiga,  in  Osier's  "Modern  Medicine,"  gives  the 
following  instance : 

In  a  village  called  Momma-Mura,  at  jSTobechi,  in  Japan,  in  1900,  a 
dysentery  epidemic  broke  out  in  houses  situated  near  each  other.  It  was 
proved  that  the  well,  used  by  all  the  households  suffering  from  the  dis- 
ease, was  infected  with  the  dysentery  bacillus.  We  have  also  an  in- 
teresting example  of  river-water  infection  in  Japan.  There  is  a  village 
called  Mitake-Mura  in  the  district  ]\Iiyagi-Iven,  through  which  a  river 
flows.  Fishing  and  swimming  are  prohibited  in  it  because  of  fish  breed- 
ing. In  the  late  summer  of  1899,  the  prohibition  having  been  removedy 
the  men  of  the  village  were  very  glad  to  be  allowed  to  fish  and  swim 
once  more  in  the  river.  However,  after  four  or  five  days  an  epidemic  of 
dysentery  broke  out  with  10  patients  on  the  first  day,  and  increa'sing' 
numbers  daily  afterward.  There  were  in  all  413  cases,  of  which  Il5^ 
were  boys  under  ten  years  of  age.  After  investigation  it  was  foundl 
that  there  was  an  epidemic  of  dysentery  in  a  village  higher  up  the  river, 
and  the  water  had  been  soiled  with  the  infected  clothes. 

Epidemics  of  bacillary  dysentery  in  this  country  in  institutions  have 
not,  as  a  rule,  been  associated  with  water. 

The  Entameba  histolytica,  causing  amebic  dysentery,  was  recovered 
by  Musgrave  and  Clegg^  from  17  to  61  samples  of  the  public  water 
supply  of  Manila  and  was  found  in  tanks  used  for  holding  distilled 
water  and  also  in  many  wells.  Eecently  Allan  ^  has  reported  a  small 
outbreak  of  amebic  dysentery  in  Xortli  Carolina  due  to  an  infected 
well. 

Diarrhea. — Polluted  waters  not  infrequently  cause  diarrhea,  some- 
times as  widespread  epidemics,  sometimes  as  small  outbreaks  or  sporadic 
cases.  Whenever  there  is  a  water-borne  outbreak  of  typhoid  fever  or 
cholera  there  are  also  a  large  number  of  cases  of  diarrhea  and  gastro- 
intestinal disturbances  in  which  the  precise  etiological  factor  has  not 
been   discovered.     Some  of  these  cases  may  be  mild  instances  of  the 

^  Public  Health  Eeports,  Volume  30,  No.  48,  November    26,  1915,  p.  3473. 
^IMusgrave  and  Clegg:   Bull.  18,  Bu.  Gov.  Lab.,  P.  I.,  93;   Pvep.  Bd.  Health, 
P.  I.   1904-  05,   10. 

'Allan:    J.  A.   M.  A.,   Chicago,    1909,   LIII,    1561. 


946  WATEE  AND  ITS  EELATION  TO  DISEASE 

major  disease.  Infantile  diarrheas  are  especially  prevalent  at  siu-h  times 
and  very  likely  are  due  to  the  contaminated  water.  Thus  Eeincke  states 
that  infantile  diarrhea  was  greatly  lessened  after  the  improvement  in 
the  water  supply  of  Hamburg.  The  same  phenomenon  was  noted  by 
Hiram  0.  Mills  after  the  filtration  of  the  water  supply  of  Lawrence, 
'Mass.  Sedgwick  noted  an  excessive  prevalence  of  both  typhoid  fever 
and  diarrhea  ,in  Burlington  and  attributed  the  diarrhea  to  the  sewage 
contamination  of  the  water  supply.  Whipple  states  that  in  Albany 
there  was  a  reduction  of  57  per  cent,  in  the  mortality  from  diarrheal 
diseases  after  the  introduction  of  filtration  in  1898.  Chapin  questions 
whether  such  statistical  evidence  is  sufficient  to  incriminate  water  as 
an  influence  to  the  causation  of  diarrheal  diseases. 

It  is  generally  believed  that  diarrhea  may  be  brought  on  by  changes 
from  a  hard  to  a  soft  water ;  also  by  organic  and  inorganic  impurities. 

ISTumerous  outbreaks  of  diarrhea  have  been  attributed  to  the  follow- 
ing microorganisms  in  water,  viz. :  B.  coli,  B.  enteritidis  of  Gaertner, 
B.  pyocyaneus,  B.  proteus,  B.  aerogenes  capsulatus  of  Welch,  B.  mesen- 
tericus,  and  streptococci.  Water  containing  these  and  other  organisms 
is  not  infrequently  regarded  as  the  cause  of  outbreaks  of  gastro-intestinal 
irritation.  The  symptoms  vary  greatly  in  intensity,  but  usually  the  dis- 
ease is  not  fatal  excepting  in  the  young  and  feeble.  The  relation  be- 
tween the  diarrhea  and  the  water  is  usually  based  upon  the  fact  that 
some  species  of  microorganisms  are  found  both  in  the  water  and  in  the 
stools.  Corroborative  evidence,  such  as  the  finding  of  specific  agglutin- 
ins and  other  antibodies  in  the  blood,  lends  countenance  to  the  claim  that 
the  particular  microorganism  is,  in  fact,  the  cause  of  the  complaint. 
While  the  evidence  is  not  conclusive,  it  is  suggestive,  and  in  many  cases 
doubtless  correct. 

Malaria. — Malaria  in  relation  to  drinking  water  is  mentioned  only 
for  its  historical  interest.  Laveran  himself,  and  even  Eoss,  considered 
this  not  improbable.  Celli  attempted  to  demonstrate  this  relationship 
by  administering  water,  from  the  most  malarious  regions  of  Italy,  to 
human  beings,  daily  up  to  a  month.  He  failed  completely.  According 
to  Craig  all  other  .similar  experiments  have  similarly  proved  negative, 
except  one  instance  studied  by  Eoss,  in  which,  however,  the  conditions 
of  the  experiment  were  far  from  conclusive. 

Laveran  based  his  judgment  upon  the  facts  that: 

(1)  "There  have  been  observed  cases  in  which,  in  the  same  locality, 
persons  living  in  identical  conditions,  but  using  drinking  waters  from 
different  sources,  the  one  group  being  attacked  in  large  proportion  while 
the  other  group  of  persons  are  scarcely  affected  at  all. 

(2)  "In  certain  otherwise  unhealthy  localities  the  paludal  fevers 
have  been  seen  to  disappear  l)y  supplying  pure  drinking  water  instead 
of  tlie  previously  stagnant  waters. 


THE  SAIsnTATIOX  OF  SWi:\Dnxrr  TOOLS  917 

(3)  "In  localities  otherwise  healthy  one  cau  contract  intermittent 
fever  from  drinking  the  water  from  an  unhealthy  locality. 

(4)  "Travelers  in  malarial  countries  have  found  that  on  boiling 
their  drinking  water  they  escaped  the  disease  in  a  large  proportion  of 
cases." 

These  conclusions  are  especially  instructive,  as  they  illustrate  some 
of  the  sources  of  error  in  epidemiological  studies.  Similar  errors  were 
made  in  the  case  of  yellow  fever  before  the  discovery  of  mosquito  trans- 
mission; and  in  other  diseases. 

Yellow  Fever. — Yellow  fever  was  formerly  associated  with  drinking 
water,  but  we  now  know  that  water  plays  no  part  in  the  transmission  of 
yellow  fever  other  than  breeding  the  Stegomyia  calopus.  In  my  studies 
at  Vera  Cruz  I  crushed  a  large  number  of  infected  yellow  fever  mos- 
quitoes and  mixed  the  mass  in  some  water.  This  mixture  was  then 
given  by  the  mouth  to  several  volunteers,  with  entirely  negative 
results. 

Animal  Parasites. — The  eggs,  larvae,  or  other  stages  in  the  life  cycle 
of  various  intestinal  parasites  may  enter  the  body  in  drinking  water. 
Thus  the  eggs  of  Ascaris  lumbricoides  are  discharged  in  the  feces,  which 
may  contaminate  streams  and  then  be  returned  to  the  mouth.  Some 
cases  of  infection  with  this  parasite  probably  occur  in  this  way.  Oxyuris 
vermicularis,  the  pinworm,  and  Trichuris  trichiura,  the  whipworm,  may 
similarly  be  contracted  through  drinking  water.  The  guinea  worm, 
Dracunculus  medinensis,  invades  the  skin  during  bathing  and  may, 
perhaps,  also  be  contracted  by  the  mouth  in  drinking  water.  The  living 
embryos  of  this  worm  are  liberated  and  find  their  way  into  fresh  water. 
There  they  enter  the  bodies  of  the  common  fresh-water  flea,  Cyclops 
quadricornis,  which  acts  as  the  intermediate  host. 

It  is  fairly  well  established  that  the  eggs  of  the  hookworm  may  be 
taken  into  the  stomach  through  drinking  water,  and  the  same  is  as- 
sumed of  the  similar  parasite  of  Cochin  China  diarrhea. 

The  Bilharzia  liaematoUa,  and  very  possibly  other  intestinal  parasites, 
may  likewise  be  transmitted  through  drinking  water. 


THE  SANITATION  OF  SWIMMING  POOLS 

The  problem  of  the  swimming  pool  is  a  good  example  of  an  institu- 
tion devised  to  improve  hygienic  conditions,  yet  the  device  itself  may 
be  a  hygienic  menace.  Swimming  pools  are  nothing  more  or  less  than 
common  bath  tubs.  The  growing  popularity  of  swimming  pools  has  led 
to  an  increased  interest  in  the  sanitary  conditions  that  prevail  in  them. 
There  is  no  longer  any  doubt  that  they  can  and  sometimes  do  transmit 
disease.     When  the  use  of  swimming  pools  is  made  compulsory,  as  is 


948  WATEE  AND  ITS  EELATTON  TO  DISEASE 

the  case  with  pupils  of  some  secondary  sclioois,  a  serious  duty  of  sani- 
tary supervision  and.  responsibility  arises. 

The  diseases  contracted  in  swimming  pools  are  intestinal  infections; 
inflammatory  infections  of  the  upper  respiratory  tract  and  conjunctiva; 
injury  and  inflammation  of  the  ears;  venereal  and  skin  diseases,  etc. 
Typhoid  fever  and  diarrheal  conditions  have  been  traced  on  reasonable 
reliable  evidence  to  swimming  pools  such  as  are  installed  by  private 
individuals,  or  found  in  colleges  and  universities,  public  and  private 
schools,  gymnasiums,  steamships,  and  special  bathing  establishments. 

The  chief  danger  of  infection  comes  from  the  water,  if  not  kept 
clean,  or  from  the  towels  and  swimming  suits,  if  not  disinfected.  The 
source  of  the  infection  comes  in  almost  all  instances  from  the  persons 
of  swimming  pools  is  to  require  a  shower  bath  with  the  liberal  use  of 
soap  before  entering  the  tank.  At  the  same  time,  a  careful  examination 
should  be  made  of  each  person  to  determine  especially  the  presence  of 
skin  diseases,  running  ears,  ulcers,  conjunctivitis,  venereal  disease,  or 
signs  of  inflammation  of  the  upper  respiratory  tract. 

The  sanitary  condition  of  a  swimming  pool  is  affected  by  its  cubic 
capacity ;  the  larger  the  tank,  the  better.  The  water  should  have  an 
initial  purity  equal  to  that  of  a  safe  drinking  water  ain.d  may  be  kept 
fairly  clean  by  filtration  and  reasonably  safe  by  bleaching  powder.  The 
combination  of  refiltration  to  clean  the  water  and  chlorination  to  dis- 
infect the  water  is  the  best  present  available  method  to  keep  the  water 
of  swimming  pools  in  satisfactory  sanitary  conditions.  Occasional 
use  of  sulphate  of  copper  may  be  necessary  to  keep  down  excessive 
growth  of  algae. 

The  bathers  are  constantly  introducing  pollution  and  occasionally 
infection.  To  offset  this,  disinfection  should  be  continuous,  at  least  it 
should  be  most  eifective  at  the  time  when  the  pool  is  in  use.  Hypo- 
chlorite is  excellent  for  occasional  or  terminal  disinfection,  but  as  it 
soon  becomes  oxidized,  its  effectiveness  gradually  disappears.  An  excess 
of  hypochlorite  in  the  water  is  irritating  to  the  eyes. 

Satisfactory  hygienic  conditions  in  swimming  pools  is  accomplished 
in  part  by  suitable  administration  of  the  plant,  including  the  super- 
vision of  the  working  force,  the  inspection  and  ablution  of  the  bathers 
before  they  enter  the  water,  and  their  instruction  in  pool  sanitation. 
Finally,  sterilization  by  boiling  or  steaming  of  the  towels  and  bathing 
suits  after  each  nse  will  avoid  one  of  the  sources  of  conveying  infection. 

ICE 

Ice  was  not  suspected  of  being  a  vehicle  by  which  infection  could  be 
.■spread  until  it  was  shown  in  bacteriological  laboratories  that  typhoid  and 
(Other  cultures  are  not  killed  by  freezing.     Leidy  in  1848  showed  that 


ICE  949 

water  derived  from  melted  ice  contained  not  only  living  infusoria,  but 
also  rotifers  and  worms.  Macfadyen  proved  that  the  temperature  of 
liquid  air  ( — 315°  T.)  does  not  kill  bacteria.  In  fact,  some  bacteria 
and  molds  grow  and  multiply  at  temperatures  as  low  as  0°  C.  See  also 
effects  of  cold,  page  533. 

Sedgwick  and  Winslow^  (1902)  were  the  first  to  make  quantitative 
studies  on  the  effect  of  freezing  upon  pathogenic  bacteria.  They  used 
cultures  of  the  typhoid  bacillus  and  showed  that  50  per  cent,  of  the 
organisms  die  at  the  end  of  the  first  week,  90  per  cent,  at  the  end  of 
the  second  week,  and  practically  all  at  the  end  of  13  weeks.  They  con- 
sider that  we  may  be  sure  that  in  nature  the  destruction  would  exceed 
rather  than  fall  short  of  these  figures,  for  the  experiments  were  made 
in  a  test-tube  where  all  the  bacteria  are  imprisoned,  while  in  nature  per- 
haps 90  per  cent,  are  extruded  during  the  purifying  process  of  freezing. 

As  water  crystallizes  it  excludes  suspended  matter  and  even  dissolved 
substances.  The  extent  to  which  water  thus  purifies  itself  depends,  how- 
ever, upon  conditions,  for  under  certain  circumstances  the  impurities 
may  be  entangled  or  even  concentrated  during  the  process  of  freezing. 

S.  C.  Keith  ^  considers  that  low  temperatures  alone  do  not  destroy 
bacteria.  On  the  contrary,  they  appear  to  favor  bacterial  longevity, 
doubtless  by  diminishing  destructive  metabolism.  Frozen  food  mate- 
rials, such  as  ice  cream,  milk  and  egg  substance,  favor  the  existence  of 
bacteria  at  low  temperatures,  not  because  they  are  foods,  but  apparently 
because  they  furnish  physical  conditions  somewhat  protective  of  the 
bacteria.  It  seems  likely  that  water-bearing  food  materials  freeze  in 
such  a  way  that  most  of  the  bacteria  are  extruded  from  the  water  crys- 
tals with  other  non-aqueous  matters  (including  air)  and  the  bacteria 
then  lie  in  or  among  these  matters  without  being  crushed  or  otherwise  in- 
jured. In  pure  water,  and  above  all,  in  water  in  which  the  whole  mass 
becomes  solidly  crystalline,  the  bacteria  have  no  similar  refuge,  but  are 
caught  and  ultimately  mechanically  destroyed  between  the  growing  crys- 
tals. This  explanation  would  account  in  part  for  the  absence  of  live 
bacteria  in  clear  ice,  their  comparative  abundance  in  "snowy"  ice  and 
"bubbly"  ice,  and  also  the  fact  that  the  more  watery  food  materials 
when  frozen  contain  the  fewest,  and  the  least  watery  the  most  living 
bacteria.  At  low  temperatures  metabolism  ceases  and  the  bacteria  con- 
tinue to  exist  in  a  state  of  suspended  vitality  similar  to  that  exhibited 
by  many  other  and  higher  plants  which,  in  the  far  north,  are  subject, 

^Sedgwick,  W.  T.,  and  Winslow,  C.  E.  A.:  (1)  "Experiments  on  the  Effect 
of  Freezing  and  Other  Low  Temperatures  upon  the  Viability  of  the  Bacillus  of 
Typhoid  Fever,  with  Considerations  Eegarding  Ice  as  a  Vehicle  of  Infectious  Dis- 
ease." (2)  "Statistical  Studies  on  the  Seasonal  Prevalence  of  Typhoid  Fever  in 
Various  Countries  and  Its  Relation  to  Seasonal  Temperature."  Mem.  Am.  Acad. 
Arts  and  Sci.,  Vol.  XII,  No.  5,  Aug.,  1902.  Summary,  Boston  8oc.  Med.  8ci., 
1899-1900,  Vol.  IV,  p.   181. 

'Science,  N.  8.,  Vol.  XXXVII,  No.  962,  pp.  877-879,  June  6,  1913. 


950 


WATER  AND  ITS   RELATION   'VO  J)ISKA,SE 


without  apparent  injury,  for  long  periods  to  temperatures  much  hchnv 
the  freezing  point  of  water. 

It  is  necessary  to  distinguish  between  natural  ice  and  manufactured 
ice. 

Natural  Ice. — Natural  ice  should  be  harvested  from  water  of  good 
sanitary  quality  and  handled  in  a  cleanly  manner.  Even  when  natural 
ice  is  obtained  from  a  polluted  water  the  danger  is  greatly  reduced,  not 
only  because  ice  purifies  itself  in  freezing,  but  because  natural  ice  is 
usually  stored  weeks  and  months  before  it  is  used.  There  are  plenty 
of  clean,  fresh  streams,  lakes  and  ponds  from  which  an  abundant  supply 
may  be  obtained.  It  is  comparatively  easy  to  protect  most  ponds,  from 
which  ice  is  harvested,  from  imdesirable  pollution.  Under  natural  con- 
ditions the  surface  layer  of  ice  contains  most  of  the  impurities  and  the 
lower  layers  are  relatively  purer,  for  the  reason  that  ice  grows  from 
above  downward  and  extrudes  both  suspended  and  dissolved  matters; 
the  surface,  however,  receives  additional  contamination  from  the  dust, 
snow,  flooding  and  other  sources.  It  is,  therefore,  good  practice  to  plane 
the  surface  of  snow  ice. 

The  fact  that  natural  ice  is  usually  purer  than  the  water  from  which 
it  is  taken  is  shown  by  the  following  analyses  which  give  the  chemical 
and  bacterial  composition  of  natural  ice  and  the  water  from  which  it 
was  frozen.     In  this  case  the  water  was  a  sewage-polluted  stream: 


Ice 
3  to  6  Inches  Thick 

Water 

Free  ammonia 

.008—         .034 
.156—         .214 
.05  —         .20 
2.0     —       3.0 
11.0  .—     28.5 
30.       —  210. 
10  c.  c— 10  c.  c. 

.016—         .136 
.230—         .726 
.0     —         .050 

0.8     —       3.50 
18.0     —     34.0 

2.       —     60. 

0.       —      0. 

.46—             .084 

Albuminoid  ammonia 

.146—             .276 

Nitrates. ...        

.  350—             .480 

Chlorin 

4.500—          6.000 

Hardness 

57.000—        60.000 

Bacteria  per  c.  c 

5200        —  13000 

Bacillus  coli  in 

1.       —             .1 

Free  ammonia 

.  006—             .  038 

Albuminoid  ammonia 

.116—             .166 

Nitrates 

.260—             .400 

Chlorin 

5.500— 

Hardness 

58.500—         62.000 

Bacteria  per  c.  c 

2500.       —     3900. 

Bacillus  coli  in 

1.       —      0.1c.  c. 

The  chemical  figures  in  this  table  are  in  parts  per  milUon. 

The  reduction  in  the  number  of  bacteria  is  noteworthy.  It  will  be 
noticed  that  there  was  no  diminution,  rather  an  increase  in  the  free  and 
albuminoid  ammonia. 

Manufactured  Ice.-rManufactured  ice  is  now  universally  made  by  the 
ammonia  process.  The  condensed  ammonia  in  expanding  requires 
heat  which  it  takes  from  surrounding  objects  and  in  this  way  the  water 
is  frozen.    There  are  two  distinct  processes;  one  known  as  "can  ice"  and 


ICE 


951 


the  other  as  "plate  ice."  In  the  first  case  the  freezing  takes  place  in 
rectangular  cans,  the  water  freezes  from  the  sides  of  the  can  toward  the 
center,  and  the  impurities  are  extruded  and  concentrated  in  the  core, 
which  is  often  visible  in  a  cake  of  can  ice.  In  making  can  ice  the  water 
must  first  be  distilled  or  boiled  in  order  to  drive  out  the  air,  else  the 
resulting  product  will  be  bubbly.  Plate  ice  is  made  by  freezing  water 
in  large  shallow  tanks.  The  water  freezes  upon  the  surface  and  when 
of  sufficient  thickness  is  cut  out  and  removed  in  blocks.  In  this  method 
it  is  not  necessary  to  distill  or  boil  the  water  for  the  reason  that  the 
air  is  extruded  naturally  during  the  process  of  freezing.  Plate  ice 
should  be  made  from  water  of  good  sanitary  quality,  especially  as  it  is 
not  usually  stored  a  long  time  before  it  is  used. 

When  ice  is  made  from  distilled  or  boiled  water  it  should  be  above 
reproach.  I  have  found,  however,  that  manufactured  ice  may  contain 
more  bacteria  than  the  water  from  which  it  was  made.  This  is  due  to 
uncleanly  methods.  Thus  six  specimens  of  plate  ice  made  from  water 
containing  64  microorganisms  per  cubic  centimeter  and  no  colon  bacilli 
ffave  the  followin*):  results : 


Number  of 
Sample 

Manufacturer 

Organisms  per 
Cubic    Centimeter 

Colon  Bacillus 

24 
29 
26 

C.  P.  Co 

C.  P.  Co 

G.  Ice  Co 

455 
5,000 
230 
650 
470 
8 

Absent 
In  1  c.  c. 
In  10  c.  c. 

27 

G.  Ice  Co 

Absent 

32 
34 

C.-S.  Co 

P.  Ice  Co 

Absent 
In  1  c.  c. 

The  laborers  who  work  "on  ice,"  as  it  is  termed,  scrape  considerable 
amounts  of  dirt  from  their  shoes  in  walking  over  the  cans  and  tanks, 
and  pollution  takes  place  from  other  sources. 

The  chemical  examination  of  manufactured  ice  may  show  conspicu- 
ously less  total  solids,  less  chlorin  and  less  nitrates  than  found  in  the 
water  from  which  it  was  made.  On  the  other  hand,  it  may  be  very  high 
in  free  ammonia.  This  is  accounted  for  by  the  fact  that  there  is  always 
some  leakage  of  this  gas  about  ice  factories  using  the  ammonia  process. 
Sometimes  ammonia  occurs  in  such  quantities  as  to  impart  a  distinctly 
alkaline  taste  to  the  manufactured  ice. 

There  is  no  excuse  for  uncleanly  methods  in  handling  ice  that  is 
used  on  or  in  our  foods.  The  fact  that  surface  impurities  may  be  washed 
from  a  cake  of  ice  is  no  reason  for  dragging  it  over  sputum-laden  pave- 
ments, over  dirty  railroad  platforms,  and  similar  methods  familiar  to 
all.  The  general  use  of  ice  is  a  modern  innovation.  It  has  come  into 
vogue  within  the  past  100  years.  For  the  uses  of  ice  as  a  preservative 
see  page  533. 


952  WATl^yR  AND  ITS  EELATION  TO  DISEASE 

Ice  and  Disease. — A  search  of  the  literature  discloses  but  few  instances 
of  disease  attributable  to  impurities  in  iee.  While  the  expori mental 
evidence  indicates  that  there  is  a  quantitative  reduction  of  the  number 
(of  bacteria  in  freezing,  and  that  the  imprisoned  bacteria  gradually  die, 
nevertheless  experience  has  shown  that  low  temperatures  alone  cannot 
be  depended  upon  to  remove  the  danger  of  typhoid  infection.  For  ex- 
ample, we  have  the  water-borne  epidemic  in  Plymouth,  Pa.,  in  1885, 
presMnably  produced  from  the  frozen  accumulation  of  typhoid  excre- 
ment from  a  single  case.  Very  similar  to  the  Plymouth  outbreak 
was  that  at  New  Haven,  Conn.,  in  1901.  In  only  a  few  isolated  in- 
stances, however,  has  ice  itself  been  accused  of  being  the  vehicle  by  which 
the  infection  of  typhoid  fever  has  been  spread.  It  appears  probable 
that  milder  intestiioal  diseases  may  be  caused  by  highly  polluted  ice,  of 
which  the  Eye  Beach  epidemic,  carefully  studied  by  Nichols  ^  of  Boston 
in  1875,  is  a  point  in  evidence. 

Park  ^  (1901)  described  an  epidemic  which  was  believed  to  have  had 
its  origin  in  ice  obtained  from  a  pond  in  which  it  was  shown  that  the 
;  excrement  from  a  patient  sick  with  typhoid  fever  had  been  thrown  while 
■.the  pond  was  covered  with  ice. 

In  the  second  annual  report  of  the  Board  of  Health  of  Connecticut 
r'for  1882  an  interesting  single  case  of  typhoid  feve^  is  cited  as  probably 
(derived  from  ice. 

Derange^  (1898)  described  an  epidemic  of  typhoid  fever  attributed 
ito  ice  among  eight  lieutenants  in  a  regiment  stationed  at  Eennes  in  the 
amttumn  of  1895.  The  implication  of  the  ice  in  this  instance  rests  upon 
a  doubtful  chain  of  evidence,  however,  and  no  mention  is  made  of  other 
possible  factors. 

Hutchins  and  Wheeler*  (1903)  report  an  epidemic  of  typhoid  fever 
in  the  St.  Lawrence  State  Hospital,  three  miles  below  Ogdensburg, 
N.  Y.,  which  seems  to  have  been  due  to  impure  ice.  The  disease  was 
endemic  in  the  hospital  for  ten  years,  increasing  from  two  cases  with 
the  opening  of  the  hospital  in  1890  to  forty  cases  in  1900.  Although 
the  water  supply,  tested  bacteriologically  and  chemically,  gave  negative 
results,  all  observers  agreed  that  the  disease  was  water-borne.  In  De- 
cember, 1900,  the  source  of  the  water  supply  was  changed  to  the  Oswe- 
gatchie  Eiver,  a  small  Adirondack  stream  supplying  Ogdensburg.  This 
practically  put  a  stop  to  the  disease,  for  there  were  no  cases  of  typhoid 
that  were  not  clearly  contracted  elsewhere  until  October,  1902. 

*  Nichols,  A.  H. :  "Report  on  an  Outbreak  of  Intestinal  Disorder  Attrib- 
utable to  the  Contamination  of  Drinking  Water  by  Means  of  Impure  Ice," 
Seventh  Ann.  Rep.,  S.  B.  H.,  Mass.,  1876,  p.  467. 

^Park,  W.  H. :    TirchoioHirsch's  Jalirhericht  f.  1901.  p.  16. 
'Dorange:    "Epidemic    de    Fifevre   Tvphoide    du    a    I'lngestion    de    Glace   Im- 
pure," Rev.  d'Hyg.,  Vol.  XX,  1898,  p.  295. 

*  Hutchins,  R.  H.,  and  Wheeler,  A.  W. :  "An  Epidemic  of  Typhoid  Fever 
Due  to  Impure  Ice,"  Am.  Jour.  Med.  Sci.,  Vol.  CXXVI,  1903,  p.  680. 


EEFEEENCES  953- 

Following  this  eight  persons  were  attacked,  seven  of  whom  were 
employees  in  the  dining-room.  It  seems  the  milk  "could  not  have  been 
infected."  The  water  was  excluded  and  other  sources  studied,  with 
negative  results.  The  ice  fell  under  suspicion.  It  had  recently  been 
taken  from  a  newly  opened  ice-house.  The  ice  had  been  harvested  from 
the  St.  Lawrence  Eiver  at  about  the  same  spot  as  the  ice  previously 
used.  It  was  gathered  in  February,  and  consequently  had  been  stored 
for  seven  months.  This  ice  disclosed  a  contamination  of  30,400  bacteria 
per  cubic  centimeter  on  agar  plates  and  50,400  on  gelatin.  Of  eight 
fermentation  tubes  three  showed  the  presence  of  colon  bacilli. 

The  stock  of  ice  was  then  examined.  In  the  center  of  certrin  cakes 
were  found  foreign  substances  in  the  form  of  black  or  dark  brown 
granular  matter.  Examined  under  the  microscope,  this  matter  was 
found  to  be  teeming  with  bacteria,  from  which  both  the  colon  and 
typhoid  bacillus  were  isolated  in  pure  culture. 

With  the  discontinuance  of  the  use  of  this  infected  ice  the  epidemic 
gradually  subsided.  There  were  in  all  thirty-nine  cases.  The  evidence 
of  this  outbreak  was  studied  by  Hill,  who  doubted  the  relation  of  the 
ice  to  the  disease. 

REFERENCES 

Report  of  the  Committee  of  the  American  Public  Health  Assn.,  Stand- 
ard Methods  of  Water  Analysis.    2nd  Ed.  1912. 

Whipple,  G.  C. :  The  Microscopy  of  Drinking  Water.  3rd  Ed.  N'.  Y., 
1914.    Wiley  &  Sons. 

Prescott,  S.  C,  and  Winslow,  C-E.  A. :  Elements  of  Water  Bacteriology. 
3rd  Ed.     N.  Y.,  1913.     Wiley  &  Sons. 

Savage,  W.  G. :  The  Bacteriological  Examination  of  Water  Supplies. 
Phila.,  1906.    Blakiston's  Son  &  Co. 

Thresh,  J.  C. :  The  Examination  of  Waters  and  Water  Supplies.  2nd 
Ed.,  Phila.,  1914.     Blakiston's  Son  &  Co. 

Turneaure,  F.  E.,  and  Russell,  H.  L. :  Public  Water  Supplies.  N.  Y., 
1907.     Wiley  &  Sons. 

Mason,  W.  P. :     Water  Supply.     3rd  Ed.,  K  Y.,  1902.  Wiley  &  Sons. 

Hazen,  A. :  Clean  Water  and  How  to  Get  It.  N.  Y.,  1907.  Wiley  & 
Sons. 

Don,  J.,  and  Chisholm,  J.:  Modern  Method  of  Water  Purification.  2nd 
Ed.    N.  Y.,  1913.    Longmans,  Green  &  Co. 

For  typical  and  composite  analyses  see: 

Clarke:  The  Data  of  Geochemistry,  Chemistry  and  Physics,  54,  U.  S. 
Geological  Survey,  1908,  Bull.  No.  330,  Series  E. 

The  Municipal  Water  Supplies  of  Illinois.  Bull,  of  the  111.  State  Board 
of  Health,  June,  1908,  IV,  6. 

Annual  Reports  of  the  Massachusetts  State  Board  of  Health. 

Bulletins  of  the  IT.  S.  Geological  Survey.  Water  supply  paper.  Some 
working  analysis. 


SECTION  VII 

SEWAGE  DISPOSAL 

By  George  C.  Whipple 
Professor  of  Sanitary  Engineering  in  Harvard  University 

Importance  of  Speedy  Removal  of  Fecal  Matter. — The  basic  principle 
that  underlies  all  methods  of  sewage  disposal  is  to  get  rid  of  the  sewage 
as  speedily  as  possible,  with  the  least  nuisance  to  the  smallest  number 
of  people,  with  the  least  damage  to  health  or  property,  and  at  the  small- 
est cost.  Experience  has  shown  that  failure  to  remove  human  excre- 
mentitious  matter  from  a  community  promptly  and  properly  is  a  menace 
to  the  public  health.  Privies  and  cesspools  should  not  be  tolerated  in 
a  closely  built  up  area.  Unless  more  than  ordinary  care  is  exercised 
their  existence  may  give  opportunity  for  the  spread  of  disease  by  insects 
and  animals  and  by  the  pollution  of  local  wells.  Statistics  show  that  the 
abandonment  of  privies  and  the  substitution  of  sewerage  systems  have 
reduced  the  general  death  rate  in  many  a  city.  Thus  Dr.  Boobyer  has 
reported  that  at  Xottingham,  England,  in  a  period  covering  ten  years 
typhoid  fever  cases  occurred  in  2.7  per  cent,  of  the  houses  that  were 
provided  with  privies,  in  .0.83  per  cent,  of  the  houses  where  pail  closets 
were  used,  and  in  only  0.18  per  cent,  of  the  houses  that  had  water-closets 
connected  with  the  sewers.  Similarly,  Dr.  Porter  has  stated  that  in 
Stockport,  England,  during  the  years  1893-7  typhoid  fever  occurred  in 
3.4  per  cent,  of  the  houses  where  there  were  privies,  but  in  only  1.2  per 
cent,  of  the  houses  that  had  sewer  connections,  these  figures  being  based 
on  a  study  of  over  18,000  houses.  In  Munich,  when  sewers  were  con- 
structed in  1856-9  the  typhoid  fever  death  rate  fell  from  242  to  166  per 
100,000;  later,  after  an  improved  water  supjily  and  other  'sanitary 
reforms  had  been  brought  about,  the  typhoid  fever  death  rate  fell  to  a 
nmch  lower  figure. 

By  taking  special  precautions  against  the  spread  of  infection  through 
the  agency  of  flies,  either  by  preventing  their  breeding  or  preventing 
them  from  obtaining  access  to  fecal  matter,  and  by  closing  polluted  wells 
in  crowded  districts,  the  dangers  from  privies  and  cesspools  may  be 
greatly  reduced.^  Sometimes  it  is  wiser  to  do  this  in  villages  and 
small  towns  than  to  go  to  the  expense  of  introducing  sewerage  systems, 

*  For  the  dangers  of  polluting  the  soil  with  feces  see  chapter  on  "Soil." 

955 


956  SEWAGE  DISPOSAL 

with  perhaps  the  attendant  difficulty  and  expense  of  purifying  the  sew- 
age after  collection. 

Ordinarily  in  this  country  sewerage  systems  and  public  water  sup- 
plies are  introduced  in  towns  where  the  population  exceeds  about  3,000, 
and  in  smaller  places  if  the  population  is  concentrated.  This  is  so  gen- 
erally true  that  towns  that  have  less  than  2,500  or  3,000  population  are 
classed  as  "rural,"  the  larger  towns  being  called  "urban." 

Dry  Earth  System. — The  dry  earth  system,  much  in  vogue  before  the 
general  introduction  of  the  water  carriage  system,  is  now  but  little  used ; 
yet  under  some  conditions  it  has  advantages.  With  this  method  the 
water-closets  are  replaced  by  removable  water-tight  receptacles,  or  pails, 
in  which  the  fecal  matter  is  kept  covered  with  dry  earth,  ashes,  or  some 
similar  material.  The  pails  are  collected  at  frequent  intervals,  prefer- 
ably daily,  and  a  clean,  empty  pail  substituted.  The  material  is  usually 
buried  in  the  ground.  For  isolated  houses,  for  temporaary  camps  of  la- 
borers, for  small  scattered  summer  colonies,  and  for  houses  situated  near 
streams  or  lakes  used  for  public  water  supplies  this  method  is  satisfac- 
tory, and  is  often  the  best  possible  method,  provided  that  proper  care  is 
taken  by  the  user  and  the  collector.  Cleanliness  in  handling,  the  pro- 
tection of  the  material  against  flies,  regular  and  frequent  collection,  occa- 
sional disinfection  of  the  pails,  and  prompt  burial  in  proper  soil  are  es- 
sential to  success. 

Water  Carriage  System. — So  accustomed  are  we  to  present  methods 
of  sewerage  that  it  is  hard  to  realize  that  the  system  of  water  carriage 
of  fecal  matter  is  less  than  a  century  old.  Up  to  1815  the  public  drains 
of  London  were  not  permitted  to  receive  excreta;  in  Boston  fecal  mat- 
ters were  rigidly  excluded  from  the  sewers  until  1833;  and  in  Paris  this 
was  the  case  even  up  to  1880. 

Following  the  report  of  the  Health  of  Towns  Commission  in  Eng- 
land in  1844,  water-closets  were  rapidly  introduced,  and  in  1847  their 
connection  with  the  sewers  was  required  by  law.  The  modern  sewerage 
system,  therefore,  dates  from  about  the  middle  of  the  last  century. 
Chesbrough  designed  a  general  sewerage  system  in  Chicago  in  1855. 
Boston's  first  sewerage  commission  was  appointed  in  1875.  Baltimore 
was  without  a  sewerage  system  until  within  a  few  years,  and  even  now, 
1912,  the  system  has  not  been  fully  completed,  nor  have  many  houses 
been  connected  with  it. 

The  introduction  of  the  water  carriage  system  accomplished  its  pur- 
pose and  effectually  did  away  with  the  offensive  accumulations  of  filth 
around  city  dwellings,  but  it  gave  rise  to  a  series  of  other  problems  that 
sanitarians  are  now  endeavoring  to  solve.  The  sewers  were  naturally 
built  to  discharge  their  contents  into  the  nearest  available  body  of  water 
— into  river,  lake,  or  harbor,  according  to  the  situation  of  the  city. 
Where  the  streams  were  relatively  large,   no  nuisance  was  caused  by 


SEWAGE  DISPOSAL  957 

doing  this,  but  where  the  streams  were  relatively  small  foul  conditions 
soon  arose,  and  it  became  necessary  to  reduce  the  amount  of  organic  mat- 
ter discharged  from  the  sewers  into  them.  Water  supplies  also  became 
infected  and  in  some  instances  great  epidemics  followed,  while  infection 
was  spread  in  other  minor  ways.  Thus  the  problem  of  the  removal  of 
fecal  matter  was  sometimes  solved  at  one  place  only  to  reappear  else- 
where. Litigation  also  arose  between  riparian  owners  along  the  water 
courses,  involving  damages  caused  by  the  pollution  of  the  water. 

The  problem  has  thus  broadened  from  a  local  one  to  one  in  Avhicli 
different  cities  and  even  different  states  have  become  involved.  It  is  to 
the  solution  of  these  problems  of  maintaining  our  streams  and  lakes 
and  harbors  in  a.  satisfactory  condition  that  sanitarians  are  now  earnestly 
devoting  themselves. 

Separate  and  Combined  Systems. — The  sewers  and  drains  of  a  city 
are  used  for  various  purposes,  the  two  most  important  ones  being  the 
removal  of  domestic  house  sewage,  and  the  rain  water  that  falls  on  roofs, 
yards,  sidewalks,  and  streets.  Sometimes  the  same  system  of  sewers  is 
used  to  carry  both  domestic  scAvage  and  storm  water.  Such  is  called 
a  combined  system.  Sometimes  the  storm  water  is  carried  in  relatively 
large  drains,  or  allowed  to  flow  along  in  the  street  gutters,  while  the 
domestic  sewage  is  carried  in  a  separate  system  of  sewers  of  smaller 
size.  The  choice  of  the  two  systems  depends  upon  the  local  situation,  but 
in  general  the  following  conditions  control. 

The  combined  system  is  the  older  and  the  one  more  commonly  used 
in  large  cities  and  crowded  communities,  for  it  is  cheaper  than  a  dual 
system,  where  both  separate  sewers  for  the  house  sewage  and  drains  for 
the  storm  water  are  required.  Where  the  storm  water  can  be  allowed 
to  flow  off  in  the  gutters  without  serious  inconvenience  from  flooding 
the  separate  system  is  cheaper,  as  the  pipes  are  smaller.  Where  the 
sewage  must  be  pumped  or  carried  long  distances  in  pipes  or  puri- 
fied by  expensive  methods  the  advantages  lie  with  the  separate  sys- 
tem, as  the  quantity  of  sewage  is  less  and  its  flow  more  constant.  From 
the  sanitary  standpoint  either  method  is  satisfactory.  The  choice 
of  the  two  systems  depends  upon  various  engineering  questions  involv- 
ing cost,  so  that  the  matter  is  one  that  should  be  submitted  to  an 
engineer. 

Sewerage  systems  consist  of  house  sewers  or  house  drains  that  convey 
the  sewage  to  the  street  sewers  or  lateral  sewers.  These  unite  in  what 
are  termed  district  sewers,  and  the  latter  sometimes  unite  in  one  or 
more  trunlc  seioers  of  large  size.  Relief  setvers  are  sometimes  built 
parallel  to  old  sewers  of  inadequate  capacity,  and  storm  sewers  are  some- 
times built  to  carry  away  surface  water,  while  underdrains  may  be  used 
in  connection  with  the  separate  system  to  remove  some  of  the  ground 
water.     Intercepting  seivers  are  sometimes  built  parallel  to  a   stream 


958  SEWAGE  DISPOSAL 

for  collecting  the  sewage  from  a  imml^er  of  district  sewers  and  convey- 
ing it  to  a  safer  point  of  discharge.  When  intercepting  sewers  are  used 
with  the  combined  system  they  are  not  designed  to  carry  all  of  the  flow 
at  times  of  storm,  bnt  are  provided  with  overflows,  so  that  the  excess  of 
storm  water  discharges  into  the  ri\-cr  at  various  points  of  overflow. 
This  is  a  matter  of  importance  and  one  to  be  remembered  in  connection 
with  the  purification  of  sewage,  for  the  quantity  of  sewage  that  passes 
these  overflows  at  times  of  heavy  rain  may  amount  to  25  per  cent,  or  50 
per  cent,  or  more  of  the  sewage,  and  during  the  course  of  the  year  may 
amount  to  from  2  per  cent,  to  5  per  cent.,  or  even  more,  of  the  entire 
sewage  of  the  city.  Such  overflow  water  is  almost  never  purified.  At 
Birmingham,  England,  Watson  has  estimated  that,  in  s-pite  of  the  elabo- 
rate provisions  for  purification,  a  large  part  of  the  city's  sewage 
is  at  times  discharged  untreated,  and  at  Milwaukee  the  Sewerage  Com- 
mission estimated  that  nearly  2  per  cent,  of  the  sewage  would 
fail  to  be  collected  by  a  very  liberally  designed  system  of  intercepting 
sewers. 

Quantity  of  Sewage. — The  volume  of  sewage  flowing  in  a  separate 
system,  or  in  a  coml)ined  system  during  dry  Aveather,  does  not  differ 
materially  from  the  water  consumption  of  the  city.  In  small  towns 
this  may  be  as  low  as  40  or  50  gallons  per  capita  daily,  although  ordi- 
narily it  is  rather  more  than  this.  In  large  cities  it  may  amount  to  from 
100  to  200  gallons  per  capita,  and  more  than  this  in  extreme  cases. 

Intercepting  sewers  are  commonly  designed  to  provide  for  a  flow  of 
300  to  400  gallons  per  capita  daily.  The  amount  of  storm  water  depends 
upon  climatic  conditions,  and  for  this  subject  engineering  books  should 
be  consulted.  The  flow  of  sewage  fluctuates  hourly,  and  the  maximum 
may  be  from  50  to  100  per  cent,  of  the  daily  average,  while  greater 
fluctuations  may  be  found,  especially  in  cities  where  large  quantities 
of  water  are  used  in  manufacturing. 

Composition  of  Sewage. — A  city's  sewage  consists  of  the  public  water 
supply  soiled  with  the  waste  products  of  human  life  and  refuse  from 
household  and  factory,  increased  by  a  certain  amount  of  ground  water 
which  leaks  into  the  sewers,  and,  in  the  combined  system,  by  varying 
quantities  of  rain  water  and  street  wash.  Disintegrating  and  decom- 
posing as  it  flows,  the  sewage  gradually  becomes  a  more  or  less  homo- 
geneous suspension  of  fine  particles  in  water,  with  organic  and  mineral 
matter  in  solution.  The  longer  the  sewage  flows  or  stands,  the  more  its 
constituents  become  disintegrated;  fecal  matter  and  paper  become  un- 
recognizable as  such;  bacteria  increase  enormously,  and  assist  in  the 
breaking  down  of  the  complex  organic  compounds.  The  oxygen  orig- 
inally present  in  the  water  becomes  reduced  and  flnally  disappears,  so 
that  from  a  fresh  condition  the  sewage  becomes  first  stale  and  then 
"septic."    Mixed  witli  the  putrefying  organic  matter  and  the  swarming 


SEWAGE  DISPOSAL  959 

hosts  of  bacteria  harmlessly  engaged  in  their  beneficent  work  of  de- 
stroying the  organic  matter,  there  may  be  also  bacteria  which  have  come 
from  persons  sick  with  typhoid  fever,  dysentery,  tuberculosis,  and  other 
diseases. 

Sewage  is  obnoxious  to  the  senses  because  of  its  decomposing  organic 
matter,  but  it  is  dangerous  to  health  because  of  the  possible  presence 
of  these  pathogenic  bacteria. 

Among  the  important  constituents  of  sewage  from  the  standpoint 
of  purification  are  urea,  various  proteid  substances  such  as  albumin, 
fibrin,  casein;  starch,  sugar,  and  other  carbohydrates,  fats,  soaps,  and 
other  organic  substances.  Important  among  the  elements  present  in  the 
easily  decomposable  matter  are  nitrogen  and  sulphur.  The  concentra- 
tion of  these  substances,  that  is,  the  amount  present  in  a  given  volume 
of  sewage,  depends  upon  the  per  capita  volume  of  the  sewage,  and  varies 
widely  in  different  places.  Somewhat  more  constant,  however,  are  these 
constituents  when  compared  with  the  number  of  persons  dwelling  in 
houses  connected  with  the  servers. 

The  following  figures  show  the  approximate  constituents  of  sewage 
expressed  in  terms  of  grams  per  capita  daily  and  in  parts  per  million 
when  the  volume  of  sewage  amoiints  to  100  gallons  per  capita  daily. 

Estimated  Constituents  of  Average  Sewage 

(After  Fuller) 

Grams  per         Parts  per 

Capita  Daily.i       Million  2 

„  ,  f  Two  minutes  boiling 15 .0  39 . 6 

Oxygen  consumed  ^  t^-         •     x     1    -v  no  n  eo  n 

•^^  [  Five  minutes  boilmg 22 .0  58.0 

Free  ammonia 7.0  18.5 

Albuminoid  ammonia 2.5  6.6 

Organic 8.0  21.1 

Total "       15.0  39.6 

Chlorin 19.0  50.2 

Fats 19.0  50.2 

[Total 136.0  359.0 

Dissolved  matter  |  Mineral 99.0  261 .0 

[  Organic  and  volatile 37 . 0  98 . 0 

,    ,               r  Total 66.0  246.0 

matters  P^^^^^^ ^^'^  ^^^'^ 

^^    ^^^  [  Organic  and  volatile 40 . 0  106 . 0 

[Total 229.0  605.0 

Total  splids Mineral 152.0  402.0 

[  Organic  and  volatile 77 . 0  203 . 0 

Bacteria,  322  billion  per  capita  daily. 

^  These  figures  also  indicate  parts  per  million  if  tlie  per  capita  volume  of 
sewage  is  264  gallons  per  day. 

^Assuming  a  per  capita  volume  of  100  gallons  per  day. 


Nitrogen  as . 


960  SEWAGE  DISPOSAL 

The  methods  of  sewage  analyses  at  jjresent  are  practically  the  same 
as  those  used  in  the  analysis  of  water.  (See  p.  821.)  They  are  not 
in  all  respects  satisfactory. 

Ventilation  aiid  Flushings  of  Sewers. — The  old  bugaboo  of  sewer  gas 
that  frightened  our  fathers  before  the  days  of  bacteriology  is  no  longer ' 
feared  by  sanitarians,  although  its  influence  still  pervades  the  antique 
plumbing  regulations  in  force  in  many  places.  It  is  indeed  desirable 
to  keep  the  air  of  sewers  from  mixing  with  the  air  we  breathe — the 
debilitating  influence  of  all  impure  air  should  be  avoided — but  the 
danger  of  any  one's  becoming  infected  Avith  the  germs  of  disease  by 
breathing  sewer  gas  is  ordinarily  so  extremely  small  as  to  be  quite  neg- 
ligible. 

The  water  carriage  system  ofi^ers  practically  no  danger  to  the  public 
health  during  the  transmission  of  sewage.  In  many  cities  the  sewers 
are  ventilated  by  allowing  a  free  flow  of  air  from  the  sewers  through 
the  house  drains,  the  individual  house  fixtures  only  being  trapped.  This 
method  is  apparently  safe,  provided  the  plumbing  is  of  substantial 
character.  If  it  is  not,  it  is  better  to  place  a  trap  upon  the  main  house 
drain.  It  is  believed  that  in  the  future  plumbing  will  develop  along  the 
lines  of  simplicity  and  improved  quality  of  materials  and  work,  and 
that  the  present  complicated  system  of  traps  and  vents  will  be  abandoned. 

The  catch-basins,  through  which  the  street  wash  enters  the  sewers, 
are  trapped  against  the  egress  of  sewer  air.  The  water  that  stands  in 
them  is  a  prolific  breeding  place  for  mosquitoes.  Unless  catch-basins 
are  frequently  cleaned,  the  accumulating  organic  matter  putrefies  and 
the  odor  from  it  may  be  worse  than  that  of  the  air  of  the  sewer.  Catch- 
basins  are  being  omitted  from  some  of  the  best  designed  modern  sewer- 
age systems. 

Combined  sewers  are  sufficiently  flushed  by  the  storms.  Separate 
sewers,  if  laid  on  proper  grades,  need  little  or  no  flushing.  It  has  been 
common  in  the  past  to  employ  flush  tanks  at  the  end  of  lateral  sewers, 
but  these  are  troublesome  and  waste  much  water. 


STREAM  POLLUTION 

Sewage  Disposal  by  Dilution. — The  readiest  method  of  sewage  dis- 
posal, and  the  one  which,  until  within  the  last  few  years,  has  been  uni- 
versally practiced  in  this  country,  is  to  allow  the  sewage  to  flow  with- 
out treatment  into  the  nearest  stream  or  lake  or  harbor.  This  method 
is  known  as  disposal  by  dilution.  It  is  a  proper  and  satisfactory  method 
of  disposal  where  the  dilution  is  sufficient.  It  is,  however,  capable  of 
abuse,  and  from  its  abuse  water  supplies  may  become  polluted,  oyster 
beds  may  becomes  infected,  and  in  severe  cases  streams  may  be  so  over- 


STREAM  POLLUTION  961 

loaded  with  sewage  as  to  become  an  offense  to  sight  and  smelh  Properly 
restricted,  however,  the  sewage  is  effectively  disposed  of,  the  heavy 
particles  settle  to  the  bottom,  the  organic  matter  is  oxidized  by  the  oxy- 
gen dissolved  in  the  water,  and  the  bacteria  are  gradually  dispersed,  con- 
sumed by  other  organisms,  killed  by  sunlight,  or  otherwise  destroyed. 
These  agencies  bring  about  the  phenomenon  known  as  the  self-purifica- 
tion of  streams. 

While  it  is  true  that  hygienic  and  sanitary  considerations  materially 
affect  the  use  of  rivers  and  waterways  as  vehicles  for  the  reception,  trans- 
mission, and  ultimate  disposal  of  sewage,  the  question  is  primarily  an 
economic  one.  The  power  of  streams  to  transport  suspended  matter  and 
the  ability  of  natural  bodies  of  water  to  oxidize  and  destroy  offensive 
substances  represent  a  natural  resource  that  should  be  utilized  just  as 
far  as  this  can  be  done  with  safety  and  without  offense.  For  each  river 
there  is  a  limit  to  the  amount  of  permissible  pollution.  The  reasons  for 
this  limit  are  not  the  same  in  all  cases,  but  vary  according  to  the  use 
that  is  made  of  the  water  of  the  river,  and  no  universal  standard  can 
be  wisely  set  up  or  maintained.  When  the  extent  of  the  pollution  is 
such  as  to  affect  public  health  in  any  way  by  any  reasonable  use  of  the 
river  the  sanitary  aspect  of  the  situation  should  control. 

The  minimum  amount  of  water  required  to  dilute  sewage  in  streams 
is  usually  considered  to  be  from  2.5  to  4  cubic  feet  per  second  for  the 
sewage  of  one  thousand  people.  The  Chicago  Drainage  Canal  was  de- 
signed on  the  basis  of  3.3  cubic  feet  per  second  for  one  thousand  people. 
Rapidly  flowing  streams  require  less  than  this,  as  much  oxygen  is  ab- 
sorbed from  the  air.  Stagnant  streams  may  require  considerably  more 
water.  The  presence  of  certain  trade  wastes  in  the  sewage  may  mate- 
rially increase  the  dilution  required.  Por  example,  oily  matters  that  float 
on  the  surface  and  form  scums  may  interfere  with  the  absorption  of 
oxygen  from  the  air. 

In  lakes  the  relation  between  the  sewer  outfall  and  the  intake  of 
the  water  works  must  be  carefully  considered,  and  the  dispersion  of 
bacteria  by  currents  induced  by  the  wind  and  temperature  must  be 
studied.     In  harbors  the  effects  of  the  tides  must  be  taken  into  account. 

Dissolved  Oxygen  in  Water. — The  amount  of  oxygen  dissolved 
in  water  depends  largely  upon  its  temperature,  as  shown  by  the  figures 
in  the  table  on  page  962. 

Water  near  the  freezing  point  will  hold  nearly  twice  as  much  oxygen 
as  at  prevailing  summer  temperatures.  The  dilution  required  in  sum- 
mer is  therefore  greater  than  in  winter,  and  in  some  situations  it  would 
1)0  logical  to  construct  purification  plants  to  be  operated  during  the 
summer  only,  thus  making  a  material  saving  in  cost. 

Sea  water  dissolves  about  20  per  cent,  less  oxygen  than  fresh  water. 

In  order  that  the  dissolved  oxygen  may  be  used  to  its  best  advantage, 
32 


9r.2 


SEW  ACE  DISPOSAL 


it  is  necessary  to  have  the  sewage  thoroughly  and  quickly  diffused 
through  the  water.  Otherwise  the  oxygen  near  the  point  of  discharge 
may  be  too  greatly  reduced,  and  nuisance  may  result,  even  though  there 
be  plenty  of  unusual  oxygen  near  by. 

Solubility  of  dissolved  oxygen  in  water — parts  per  million 


Temp."  C. 

Oxygen 

Temp.  °  C. 

Oxygen 

Temp.  °  C. 

Oxygen 

0 

14.70 

10 

11.31 

20 

9.19 

1 

14.28 

11 

11.05 

21 

9.01 

2 

13.88 

12 

10.80 

22 

8.84 

3 

13.50 

13 

10.57 

23 

8.67 

4 

13.14 

14 

10.35 

24 

8.51 

5 

12.80 

15 

10.14 

25 

8.35 

6 

12.47 

16 

9.94 

26 

8.19 

7 

12.16 

17 

9.75 

27 

8.03 

8 

11.86 

18 

9.56 

28 

7.88 

9 

11.58 

19 

9.37 

29 

7.74 

Necessity  of  Biological  Equilibrium. — It  is  becoming  recognized 
that  the  problem  of  sewage  disposal  by  dilution  is  largely  a  biological 
one.  The  decomposition  and  oxidation  of  the  organic  matter  in  sewage 
are  brought  about  by  bacteria,  and  the  bacteria  serve  as  food  for  protozoa 
and  other  forms  of  microscopic  animal  life.  The  dissolved  organic  mat- 
ter in  sewage  serves  as  food  for  algae.  These  algae  and  protozoa  are, 
in  turn,  consumed  by  rotifers  and  Crustacea,  while  the  latter  form  the 
basis  of  the  food  supply  for  various  aquatic  animals  and  fishes.  Thus 
there  is  a  continuous  biological  cycle.  Again,  animal  forms  require 
oxygen  and  produce  carbonic  acid,  while  plants  consume  carbonic  acid 
and  produce  oxygen.^  Where  these  processes  occur  normally  and  with  a 
proper  equilibrium  maintained  between  animal  and  plant  life,  offensive 
conditions  do  not  result,  but  where  abnormal  conditions  are  produced, 
as,  for  example,  by  the  discharge  of  excessive  quantities  of  sewage  or 
trade  wastes  into  a  stream,  a  depletion  of  the  dissolved  oxygen  may 
follow,  or  there  may  be  an  over-production  of  algae,  so  that  the  condi- 
tions become  offensive.  It  is  coming  to  be  realized  that  in  order  to 
properly  determine  the  dilution  required  in  any  particular  case  the  con- 
ditions required  to  bring  about  this  condition  of  biological  equilibrium 
must  be  determined. 

Hygienic  Aspects  of  Stream  Pollution. — Considering  the  hygienic 
aspects  of  stream  pollution  with  special  reference  to  the  pollution  of 
water  supplies,  it  is  important  to  rem^ember  that  the  typhoid  fever  bacilli 
do  not  multiply  in  the  ordinary  water  of  our  streams,  but,  on  the  con- 
trary, when  discharged  into  water  they  rapidly  diminish  in  number. 
After  a  week  not  more  than  10  per  cent,  may  remain  alive,  and  after  a 
month  not  more  than  1  per  cent. 

*  When  fish  die  in  sewage  polluted  water  it  is  usually  due  to  lack  of 
oxygen. 


TKEATMENT  OF  SEWAGE  963 

It  follows  that  recent  pollution  is  the  most  dangerous,  and  that 
water  stored  in  reservoirs  and  lakes  becomes  more  and  more  safe  for 
use  as  time  of  storage  increases.  The  longevity  of  the  typhoid  bacillus  is 
much  greater  in  cold  water  than  in  warm  water.  Hence,  typhoid  fever 
epidemics  are  more  common  in  winter  than  in  summer,  and  in  northern 
climates  than  in  southern  climates. 


PROTECTION  AGAINST  POLLUTION 
WATER    FILTRATION 

Long  experience  in  this  country  and  a  much  longer  experience  in 
England  and  Germany  have  demonstrated  clearly  and  unmistakably 
that  polluted  waters  can  be  and  are  being  constantly  purified  by  means 
of  filtration  to  such  an  extent  that  they  are  reliably  vs^holesome.  In 
Germany  the  typhoid  fever  death  rates  in  the  large  cities  have  been 
reduced  to  figaires  far  below  those  of  American  cities.  In  Europe  it 
is  not  at  all  uncommon  for  the  typhoid  death  rate  to  remain  less  than 
10  per  100,000  for  ten  and  even  twenty  years  in  succession,  the  rate 
not  infrequently  dropping  as  low  as  3  and  4  per  100,000.  There  the 
filtration  of  surface  water  is  required  by  law,  and  the  efficiency  of  the 
filters  is  likewise  required  to  rise  to  a  certain  fixed  standard.  It  is 
worth  remembering  also  that  the  streams  of  Germany  are  far  from 
being  unpolluted  with  sewage,  and  that  no  general  attempt  is  made  to 
provide  sewage  purification  works  of  high  bacterial  efficiency.  Only  in 
case  of  actual  epidemics  is  the  practice  of  disinfection  of  sewage  fol- 
lowed. The  theory  that  water  filtration  is  superior  to  sewage  purifica- 
tion as  a  means  of  protecting  water  supplies  against  infection  appears 
to  prevail.    The  success  of  this  policy  has  been  amply  demonstrated. 

TREATMENT    OF    SEWAGE 

By  appropriate  processes  sewage  can  be  artificially  purified  so  that 
the  decomposable  organic  matter  is  removed  or  oxidized  and  the  bacteria 
removed  or  killed.  A  complete  purification  is  not  attempted  even  in 
the  best  conducted  plants,  as  the  processes  demanded  are  too  elaborate, 
too  expensive,  and  too  uncertain  of  results.  More  often  the'purification  is 
incomplete,  the  degree  of  purification  secured  being  adjusted  to  the  par- 
ticular needs  of  the  situation.  In  the  past  sewage  treatment  works  have 
been  built  to  remove  as  much  of  the  decomposable  organic  matter  as  was 
necessary  to  enable  the  effluent  to  be  discharged  into  some  waterway  with- 
out causing  offensive  conditions.  This  was  the  case  in  Europe,  and  espe- 
cially in  England,  where  the  streams  are  relatively  small  and  the  cities 
relatively  large  and  the  amounts  of  trade  waste  considerable. 

In  some  places  greater  emphasis  has  been  placed  on  the  removal  or 


964  SEWAGE  DISPOSAL 

destruction  of  pathogenic  bacteria,  with  the  object  of  protecting  oyster 
beds,  bathing  beaches,  or  reducing  the  "load"  on  water  filters. 

The  degree  of  purification  thus  required  varies  all  the  way  from 
a  nearly  complete  purification  down  to  a  mere  straining  out  of  the 
grosser  solids. 

Fundamental  Principles  of  Sewage  Treatment. — The  fundamental 
processes  in  sewage  treatment  are : 

(1)  Separation  of  the  suspended  matter  from  the  liquid  sewage. 

(2)  Destruction  of  the  putrescible  organic  matter  in  the  liquid 
sewage  looking  to  final  mineralization  by  the  processes  of  oxidation  and 
bacterial  action. 

(3)  The  transformation  of  the  sewage  sludge  to  a  condition  of 
stability  and  inertness  by  bacterial  action,  with  or  without  oxidation. 

(4)  Destruction  or  removal  of  the  bacteria  from  the  liquid  effluent. 
The  processes  involved  may  be  classified  as  follows: 

(1)  Preparatory  processes,  such  as  screens,  detritus  tanks,  plain 
settling  tanks,  septic  tanks,  digestion  tanks,  chemical  precipitation  tanks, 
roughing  filters. 

"(2)  Purification  processes,  such  as  sub-surface  irrigation,  broad 
irrigation,  intermittent  filtration,  contact  beds,  and  trickling  filters. 

(3)  Finishing  processes,  such  as  sedimentation  or  coarse  filtration, 
land  treatment,  disinfection. 

(4)  Sludge  disposal  by  digestion  tanks,  filter  presses,  drying  on 
land,  dumping  at  sea. 

These  processes  are  by  no  means  clear  cut.  They  overlap  at  many 
points;  they  are  used  singly  or  in  all  sorts  of  combinations. 

Preparatory  Processes. — Screening. — Sewage  is  screened  to  remove 
the  larger  substances  that  might  injure  pumps,  clog  filters,  or  appear 
as  unsightly  litter.  Coarse  screens  consist  of  gratings  of  iron  bars; 
fine  screens  of  wire  cloth.  The  amount  of  material  screened  from 
sewage  varies  from  0.1  to  1.0  cubic  yard  per  million  gallons  of  sewage, 
according  to  the  fineness  of  the  screens.  It  is  pressed  and  burned  under 
a  boiler  or  buried  in  land.  Screening  has  attained  its  greatest  develop- 
ment in  Germany. 

Sedimentation. — Sedimentation  is  the  most  important  of  the  pre- 
paratory processes.  By  allowing  the  sewage  to  flow  slowly  through 
basins  in  which  the  velocity  is  checked  some  of  the  suspended  matter  is 
deposited  and  the  sewage  clarified  accordingly.  There  are  five  types 
of  sedimentation  basins:  (1)  grit  chambers  or  detritus  tanks,  (2)  plain 
settling  tanks,  (3)  septic  tanks,  (4)  digestion  tanks,  and  (5)  chemical 
precipitation  tanks. 

(1)  Grit  Chambers. — Grit  chambers  are  small  settling  basins  in 
which  the  sewage  remains  for  a  brief  interval,  often  not  more  than  a 
fcAV  minutes,  and  where  the  velocity  is  commonly  between  10  and  30 


TEEATMENT  OF  SEWAGE 


965 


inches  per  minute.  They  require  frequent  cleaning.  The  material  col- 
lected consists  largely  of  sand  and  gravel,  but  usually  with  enough  or- 
ganic matter  to  make  the  sludge  offensive. 


Fig.  121. — Cross  Section  of  Septic  Tank. 

(2)  Plain  Settling  Tanlcs. — Plain  settling  basins  retain  the  sewage 
from  one  to  twelve  hours.  The  velocity  of  flow  is  commonly  from  0.1 
to  0.5  inch  per  minute.  Sludge  is  removed  at  frequent  intervals  in 
order  to  prevent  bacterial  decomposition. 

(3)  Septic  Tanks. — Septic  tanks  are  settling  tanks  large  enough  to 
retain  the  flow  of  sewage  from  eight  to  twenty-four  hours  or  longer,  the 
velocity  of  flow  varying  from  0.1 
to  0.3  inch  or  more  per  minute. 
The  sludge  is  allowed  to  remain  in 
the  tanks  for  long  periods,  giving 
opportunity  for  intensified  bac- 
terial action  to  take  place  in  the 
absence  of  oxygen;  that  is,  under 
anaerobic  conditions.  As  a  result 
some  of  the  solid  organic  matter  is 
liquefied  or  gasified  and  the 
amount  of  sludge  reduced.  This 
process  is  spoken  of  as  digestion. 
It  is  accompanied  by  the  presence 
of  a  scum  on  the  surface  of  the 
tank  and  a  continual  rising  and 
falling  of  sludge  through  the 
liquid.  The  amount  of  solid  or- 
ganic matter  thus  digested  varies 
from  10  per  cent,  to  40  per  cent., 
being  greatest  in  strong  domestic 
sewage.      Septic    action    does    not 

materially  improve  the  quality  of  the  effluent.  It  may,  in  fact,  make  it 
more  objectionable.  Septic  action  cannot  be  depended  upon  to  render 
sewage  safe  so  far  as  infections  are  concerned. 


^m^ 
-^^ 


Fig. 


122. — Typical   Section   of   an   Im- 
HOFF  Tank. 
a.  Compartment  for  flowing  sewage. 
/.    Sludge  digestion  compartment. 
g.  Baffle    to    prevent    gases    and    sludge 

from  rising  into  compartment  a,  but 

permitting  sediment  to  fall  into  the 

sludge  compartment. 
h-c.  Pipe  for  withdrawing  sludge. 


9GG 


SEWAGE  DISPOSAL 


(4)  Digestion  Tanks. — Tlio  best  known  type  of  digestion  tank  is 
the  Imlioff,  or  Eni.sciic'r,  tank.  Tlii.s  is  a  (l('c|)  si;[)l,i(;  tank  divided  by 
sloping  partitions  into  an  npj)er  and  a  lower  cinnpai't  incut,  so  arranged 
that  the  sewage  flows  through  the  upper  eoiupariniejjt,  wliile  the  sludge 
settles  through  023enings  in  the  partition  walls  ijito  the  lower  compart- 
ment, where  digestion  takes  place.  The  advantage  of  this  type  of  septic 
tank  is  that  the  sludge  alone  is  submitted  to  septic  action  without  allow- 
ing the  products  of  decomposition  to  mix  with  the  flowing  sewage 
above,  while  more  complete  digestion  improves  the  character  of  the 
sludge  from  the  standpoint  of  subsequent  disposal. 

The  following  figures  show  the  approximate  percentage  of  suspended 
matter  removed  by  sedimentation : 

Percentage  removal  of  suspended  matter 


Kinds  of  Sedimentation 

Period, 
Hours 

"Weak 
Sewage 

Medium 
Sewage 

Strong 
Sewage 

Grit,  or  detritus  tanks 

1 

6 
12 
24 

48 

10% 

25 

30 

40 

50 

15% 
40 
50 
65 

75 

25% 

Plain  sedimentation 

60 

Plain  or  septic  sedimentation 

Septic  sedimentation 

Septic  sedimentation 

75 
80 
85 

(5)  Chemical  Precipitation. — Sedimentation  may  be  hastened  and 
increased  by  the  use  of  chemicals.  Lime,  copperas  (ferrous  sulphate), 
and  alum  (aluminium  sulphate)  are  commonly  used.  The  active 
coagulants  are  the  hydroxids  of  iron  and  aluminum.  When  the  sewage 
itself  contains  the  necessary  amount  of  iron,  lime  only  is  needed.  When 
alum  is  used  500  to  1,500  pounds  are  required  per  million  gallons. 
At  London  the  sewage  is  treated  with  500  pounds  of  lime  and  120 
pounds  of  copperas  per  million  gallons ;  at  Worcester,  Mass.,  with  1,000 
pounds  of  lime  and  no  copperas ;  at  Providence,  E.  I.,  with  600  pounds 
of  lime  and  no  copperas ;  at  Glasgow  with  600  pounds  of  lime  and  1,000 
pounds  of  copperas. 

Purification  Processes. — Sub-surface  Irrigation. — For  small  instal- 
lations a  satisfactory  method  of  disposing  of  sewage  after  sedimentation 
is  to  discharge  it  through  3-inch  or  4-inch  tile  pipes  laid  in  the  ground 
10  to  18  inches  deep  in  rows  2%  to  3  feet  apart.  In  sandy  soils  this 
method  gives  satisfaction,  and  under  favorable  conditions  the  sewage 
of  150  to  250  people  can  be  applied  to  an  acre,  the  rate  of  application 
being  commonly  one  to  two  gallons  per  lineal  foot,  or  20,000  to  30,000 
gallons  per  acre  daily.  With  tight  soils  larger  areas  are  required. 
With  clay  soils  the  method  cannot  be  used. 

This  method  of  sewage  disposal  is  particularly  applicable  to  subur- 
ban and  rural  conditions. 

Broad  Irrigation. — Broad  irrigation  consists  in  the  ajoplication  of 


PUEIFICATION  PEOCESSES 


967 


crude  sewage  to  land,  making  it  serve  as  food  for  crops,  the  principal 
value,  however,  being  in  the  water  itself.  It  is  distributed  by  means 
of  ditches  and  other  channels  as  in  ordinary  irrigation.     The  sewage 


Fig.  123. — Chemical  Precipitation  Plant  at  Worcester,  Mass.,  Outlet. 

farms  of  Berlin  and  Paris  are  very  extensive,  the  Berlin  farms  covering 
nearly  20,000  acres.  The  rate  of  application  varies  from  3,000  to  15,000 
gallons  per  acre  daily,  an  acre  serving  for  the  sewage  of  from  100  to 
300  persons.     The  crops  raised  on  sewage  farms  frequently  pay  the 


Fig.  124. — Triple  Contact  Beds  at  Hampton,  England. 

expenses  of  operation,  but  seldom  pay  the  interest  on  the  investment 
except  in  arid  regions,  where  irrigation  is  profitable.  Broad  irrigation, 
cannot  be  successfully  used  with  clayey  soils.  The  purification  obtained 
is  usually  very  satisl'iidoi'v,  Ijotli  chemically  and  bacteriologically. 


968 


SEWAGE  DISPOSAL 


Intermittent  Sand  Filtration. — With  this  method  tlie  sewage  is 
applied  intermittently  to  heds  of  sand,  especially  prepared  for  the  pur- 
pose, in  such  quantities  that  it  quickly  soaks  away,  leaving  the  bed  ex- 
posed to  the  air  for  a  period  of  several  hours  or  several  days,  thus  giving 
opportunity  for  aeration  and  oxidation  of  the  organic'  matter.  The 
results  obtained  are  usually  very  satisfactory,  provided  that  the  filters 


INn.UENT 


^•.jviWKw^ii^ 


D/3TFHa  uypR  ■> 


«  UND£F>rtl>Airsl 


^UNOERDFtAJN 

Fig.  125. — Cross  Section  of  Intermittent  Sand  Filter. 


are  not  overloaded.  When  raw  sewage 'is  applied  directly  to  the  heds 
the  rates  of  application  vary  from  50,000  to  150,000  gallons  per  acre 
daily,  the  population  served  per  acre  being  from  300  to  1,200.  With 
preliminary  treatment  higher  rates  may  be  used,  and  the  sewage  of 
1,500  to  2,000  people  applied  per  acre.  The  filters  are  usually  divided 
into  beds  by  means  of  earth  embankments  which  cover  the  distributing 
pipes.     Often  they  are  underdrained  with  tiles  laid  20  to  30  feet  apart 


Fig.  126. — Inclined  Screen  Operated  by  Water  Wheel,  Birmingham,  England. 

in  fine  material,  or  100  feet  apart  in  coarse  material,  their  depth  below 
the  surface  varying  from  3  to  8  feet.  Crops  are  sometimes  grown  on 
these  beds,  but  agricultural  operations  are  regarded  as  a  secondary  mat- 
ter. In  v/inter  the  beds  are  plowed  into  ridges  or  the  sludge  is  collected 
into  piles  so  that  ice  may  form  and  be  supported  upon  them,  leaving 
channels  beneath  the  ice  by  which  the  sewage  can  be  distributed.  After 
a  few  weeks  or  months  the  beds  become  clogged  and  it  is  ncessary  to 


SEWAGE  FILTEATION 


969 


INFLUENT 
CHANNEL. 


rake  the  surface.     At  intervals  the  accumulated  deposit  on  the  sand 
has  to  be  scraped  off. 

The  efficiency  of  intermittent  sand  filtration  is  higher  than  that  of 
any  other  process.  Well  operated  plants  are  capable  of  removing  from 
95  to  98  per  cent,  of  the  suspended  matter  and  bacteria,  while  the  effluent 
is  quite  clear  and  non-putrescible.  The  method  is  limited,  however,  to 
regions  where  suitable  and  convenient  areas  of  sandy  soil  exist. 

PRIMAFtr    &€D 


Fig.  127. — Cross  Section  of  Contact  Bed. 

Contact  Beds. — Contact  beds  are  water-tight  compartments  filled 
with  porous  material,  such  as  broken  stone  or  coke,  and  operated  as 
follows:  The  bed  is  slowly  filled  with  sewage,  which  has  previously 
passed  through  a  septic  tank,  and  allowed  to  remain  full  for  a  brief 
period,  after  which  it  is  emptied  and  allowed  to  remain  empty  for  a 
longer  period.  A  cycle  commonly  employed  is  to  allow  one  hour  for 
filling,  two  hours  for  contact,  one  hour  for  emptying,  and  four  hours 
for  rest.  During  the  period  of  contact  the  suspended  matter  tends  to 
settle  upon  and  adhere  to  the  exposed  surfaces  of  the  broken  stone  or 


Fig.  128. — Typical  Section  of  a  Sprinkling  Filter. 

coke,  thus  forming  a  film.  While  standing  full  septic  action  occurs  and 
organic  matter  is  absorbed  by  the  film.  During  the  resting  period 
oxidation  of  this  organic  matter  takes  place.  The  purification  obtained 
in  this  way  is  partial.  Commonly,  two  or  three  contact  beds  are  used 
in  series,  the  effluent  from  the  first  passing  to  the  second,  and  that  of  the 
second  to  the  third.  The  depth  of  contact  beds  varies  from  3  to  6  or 
8  feet,  the  broken  stone  or  coke  being  from  %  inch  to  3  inches  in  size. 
The  rate  of  application  is  usually  between  300,000  and  800,000  gallons 
per  acre  daily,  one  acre  serving  a  population  of  about  5,000.  When 
properly  operated  and  receiving  the  seAvage  of  septic  tanks  contact  beds 


D70 


SEWAGE  DISPOSAL 


arc  capable  of  removing  about  65  to  70  per  cent,  of  the  organic  matter, 
80  to  85  per  cent,  of  bacteria,  and  85  to  !)0  per  cent,  of  suspended  mat- 
ter. Contact  beds  become  clogged  with  use,  and  after  periods  varyiiig 
from  five  to  eight  years  it  is  necessary  to  remove  the  stone  or  coke  and 
clean  them. 

Trickling  Filters. — Trickling  filters,  othervi^ise  called  "sprinkling 
filters"  or  "percolating  filters,"  consist  of  beds  of  porous  material  such 
as  broken  stone,  coke,  or  clinkers  upon  which  the  sewage  is  sprinkled  and 
through  which  it  percolates  to  underdrains  laid  on  a  tight  floor  beneath. 
The  entire  bed  is  arranged  with  reference  to  complete  aeration  through- 
out, in  order  that  the  organic  matter  of  the  sewage  may  become  thor- 
oughly oxidized.     The  suspended  matter  of  the  sewage  is  not  perma- 


FiG.  129. — Trickling  Filter  at  Birmingham,  England. 


nently  retained  in  the  beds,  but  is  carried  out  in  the  effluent,  which  is 
turbid  and  requires  subsequent  clarification.  The  object  of  the  trickling 
filter  is  to  change  the  character  of  the  organic  matter  so  as  to  render 
it  non-putrescible.  The  sewage  is  applied  to  the  beds  by  sprinkling 
through  fixed  sprinklers  or  by  use  of  traveling  sprinklers,  rotary  or 
rectangular,  operated  by  the  discharging  sewage  or  by  power.  The  rate 
of  application  varies  from  0.5  to  3.0  million  gallons  per  acre  daily, 
oiie  acre  of  trickling  filter  serving  a  population  of  10,000  or  more. 
The  beds  vary  in  depth  from  5  to  10  feet,  coarser  material  being  used 
for  the  deeper  beds.  Well-operated  sprinkling  filters  receiving  the 
effluent  from  plain  sedimentation  or  septic  tanks  are  capable  of  remov- 
ing from  85  to  90  per  cent,  of  the  suspended  matter  and  from  90  to  95 
per  cent,  of  bacteria,  yielding  an  effluent  that  is  non-putrescible.  This 
method  is  useful  when  sandy  areas  of  sufficient  size  are  not  available 
for  intermittent  filtration  or  are  too  expensive. 


SLUDGE  DISPOSAL  971 

Activated  Sludge  Tanks. — A  recent  form  of  tank  treatment  is  one 
which  combines  forced  aeration  with  bacterial  action.  By  pumping 
compressed  air  into  a  tank  containing  sewage  so  that  the  bubbles  rise 
through  it,  causing  the  sediment  to  be  thoroughly  agitated,  the  particles 
of  suspended  matter  after  a  few  weeks  become  coated  with  a  bacterial 
slime  so  that  colloidal  particles  become  attached  to  them.  When  this 
condition  has'  been  reached  sewage  is  allowed  to  pass  through  the  tank, 
aeration  being  maintained,  the  result  being  a  surprising  clarification  and 
reduction  in  bacterial  content.  A  certain  amount  of  nitrification  also 
takes  place.  The  operation  may  be  conducted  on  the  fill  and  draw 
principle  or  on  the  principle  of  continuous  flow.  This  process  is  being 
experimented  with  in  many  places  and  promising  results  are  being  ob- 
tained. In  principle  the  process  resembles  that  of  filtration  in  that  the 
colloidal  substances  are  brought  in  contact  with  particles  covered  with 
bacterial  slime,  in  one  case  the  grains  being  scattered  through  the  sew- 
age, in  the  other  the  sewage  being  allowed  to  filter  or  percolate  through 
the  grains. 

If  this  process  proves  successful  on  a  large  scale  it  is  destined  to 
materially  alter  present  methods  of  sewage  treatment,  as  the  structures 
required  would  be  very  simple.  The  sludge  is  said  to  be  relatively  inof- 
fensive and  well  suited  to  agricultural  use,  but  it  contains  a  large  amount 
of  water.  The  economy  of  this  method  will  depend  upon  the  cost  of  sup- 
ply air  and  the  cost  of  sludge  disposal. 

Sludge  Disposal. — The  disposal  of  sludge  is  one  of  the  most  diffi- 
cult parts  of  sewage  purification.  Grit  chambers  collect  from  0.1  to  1 
cubic  yard  of  wet  sludge  per  million  gallons  of  sewage;  plain  settling 
tanks  from  1  to  4  cubic  3^ards;  septic  tanks  from  1  to  2  cubic  yards. 
Sludge  deposited  in  plain  settling  tanks  contains  from  90  to  95  per 
cent,  of  water ;  septic  tank  sludge,  after  storage,  contains  from  80  to  85 
per  cent. ;  chemical  precipitation  sludge  from  90  to  93  per  cent. ;  Imhoff 
tank  sludge  from  80  to  90  per  cent.  Sludge  after  pressing  contains 
from  25  to  50  per  cent,  of  water.  It  has  some  manurial  value,  and  is 
used,  to  some  extent,  on  land.  As  a  general  proposition,  however,  the 
attempt  to  "utilize"  the  sludge  has  not  met  with  financial  success. 

Finishing  Processes. — Disinfection  of  Sewage. — The  best  disin- 
fectant for  sewage  or  sewage  effluents  is  "chlorid  of  lime,"  or  bleaching 
powder,  which  is  usually  applied  in  the  form  of  a  1  per  cent,  to  2  per 
cent,  solution.  The  quantities  required  are  25  to  75  pounds  per  million 
gallons  for  good  effluents  from  sprinkling  filters  or  contact  beds,  75  to 
125  pounds  for  poor  effluents,  125  to  250  pounds  for  crude  sewage,  and 
250  to  375  pounds  for  septic  sewage,  the  time  of  contact  required  vary- 
ing from  about  i/>  hour  to  2  or  more  hours.  By  properly  applying  the 
chemicals  in  these  quantities  it  is  possible  to  destroy  from  95  to  99 
per  cent,  of  the  bacteria. 


972  SEWAGE  DISPOSAL 

Choice  of  Methods, — The  choice  of  methods  to  be  used  in  any  case 
depends  upon  various  considerations,  such  as  the  nature  of  the  sewage 
to  be  treated,  the  allowable  character  of  the  effluent  considered  with  refer- 
ence to  the  use  made  of  the  water  into  which  it  is  to  be  discharged, 
the  availability  of  suitable  areas  of  land  at  proper  elevation,  and  finally 
the  cost,  both  of  construction  and  operation. 

Where  suitable  areas  of  sandy  soil  are  available  the  method  of 
intermittent  filtration  is  ordinarily  the  most  satisfactory  one  that  can 
be  adopted.  This  is  the  case  in  many  parts  of  New  England  and  in 
some  other  parts  of  our  country.  Over  much  of  the  United  States, 
however,  the  soil  is  far  too  heavy  to  allow  this  method  to  be  used  satis- 
factorily, and  when  this  is  the  case  some  of  the  newer  methods  must  be 
resorted  to,  such  as  sedimentation  followed  by  oxidation  in  trickling 
filters,  contact  beds,  etc.  Under  some  special  conditions  broad  irrigation 
may  be  desirable,  but,  generally  speaking,  this  method  is  falling  into 
disuse.  When  the  effluent  is  to  be  discharged  into  a  stream  used  for  a 
nearby  supply  of  drinking  water,  or  into  the  ocean  or  a  harbor  in  the 
vicinity  of  oyster  beds,  disinfection  may  properly  form  a  part  of  the 
process.  Chemical  precipitation  is  seldom  used  where  the  sewage  is  of 
a  strictly  domestic  character,  but  it  may  be  used  to  advantage  when  the 
sewage  contains  large  amounts  of  trade  wastes. 

Methods  for  the  purification  of  sewage  are  quite  elastic  inasmuch  as 
the  different  processes  may  be  combined  in  different  ways.  A  study  of 
the  works  that  have  been  built  in  the  United  States  during  the  last 
generation  shows  that  not  infrequently  they  have  been  made  more 
elaborate  than  was  necessary.  Often  a  simpler  design  with  a  large 
capacity  gives  better  results  than  an  elaborate  combination  of  processes 
of  limited  capacity.  Important  engineering  problems  are  almost  always 
involved  in  the  laying  out  of  sewage  treatment  works. 

Relative  Bacterial  Efficiency  of  Different  Processes. — By  way  of  re- 
capitulation the  following  figures  are  given  to  show  the  relative  sanitary 
efficiency  of  various  processes  employed  in  sewage  treatment : 

Percentage 
Removal  of  Bacteria 

Coarse  screens 0  to  5 

Fine  screens 10  "  20 

Grit  chambers 10  "  25 

Sedimentation 25  "  75 

Septic  sedimentation 25  "  75 

Chemical  precipitation 40  "  80 

Contact  beds 80  ^';  90 

Activated  sludge  process 85  "  95 

Trickhng  filters 90  "  95 

Intermittent  sand  filters 95  "  98 

Broad  irrigation 97  "  99 

Disinfection  of  raw  or  settled  sewage 90  "  95 

Disinfection  of  filter  effluents 98  "  99 


MANAGEMENT  OF  WOEKS  973 

These  figures  are  mere  approximations,  but  they  serve  to  show  how 
some  forms  of  treatment,  very  desirable  from  many  points  of  view, 
have  a  low  sanitary  efficiency.  The  septic  treatment,  for  example,  does 
not  greatly  reduce  the  number  of  bacteria  in  sewage;  in  fact,  if  the 
period  of  detention  of  the  sewage  in  the  tank  is  long  the  numbers  of 
bacteria  in  the  effluent  may  be  greater  than  those  in  the  raw  sewage. 

Manag^ement  of  Sewage  Treatment  Works. — Proper  management  of 
sewage  treatment  works  is  as  important  as  proper  design,  and  is  more 
difficult  to  secure.  It  is  a  most  regrettable  fact  that  many  treatment 
works  in  the  United  States  have  been  badly  neglected,  and,  in  conse- 
quence, have  given  inefficient  service.  Neglect  not  only  results  in  mak- 
ing the  effluent  unsatisfactory,  but  leaves  the  works  themselves  in  an 
offensive  condition.  Neglect  of  small  plants  is  more  common  than  of 
plants  large  enough  to  require  the  entire  time  of  one  or  more  attendants. 

Another  frequent  cause  of  failure  is  that  treatment  works  are  allowed 
to  become  outgrown,  so  that  the  plant  becomes  overloaded  and  the 
process  becomes  inefficient.  The  sewers  of  a  city  are  usually  designed 
for  a  long  period  in  advance — -forty  or  fifty  years — but  this  is  not  the 
case  with  treatment  works,  for  the  reason  that  such  works  can  ordi- 
narily be  enlarged  when  necessary.  This  is  sound  policy,  for  the  reason 
that  the  methods  of  purification  are  constantly  improving,  and  it  is  de- 
sirable to  take  advantage  of  these  improvements  as  far  as  possible 
whenever  enlargement  is  necessary.  But,  if  the  works  are  to  operate 
satisfactorily,  the  enlargement  must  be  made  as  the  tributary  population 
increases,  taking  advantage  of  the  state  of  the  art  at  the  time. 

The  purification  of  sewage  is  so  largely  a  chemical  and  biological 
matter  that  it  is  desirable  to  have  the  works  in  charge  of  men  trained 
in  sanitary  engineering,  with  a  laboratory  equipment  at  their  disposal. 
Tests  of  the  sewage  before  and  after  treatment  should  be  made  regularly 
in  order  to  ascertain  the  efficiency  of  the  process.  Tests  should  also 
be  made  of  the  water  into  which  the  sewage  is  discharged.  In  the 
case  of  plants  of  large  size,  provided  with  laboratories,  such  tests  are 
made  daily,  but  in  the  case  of  plants  too  small  to  constantly  employ  a 
chemist  tests  should  be  made  regularly  by  some  controlling  authority. 
Herein  lies  one  of  the  functions  of  the  State  Board  of  Health. 

Treatment  Plants  as  Nuisances.— If  sewage  treatment  works  are  prop- 
erly designed  and  carefully  operated,  and  if  they  are  enlarged  from  time 
to  time  to  meet  the  needs  of  the  growing  community,  they  need  not 
be  the  cause  of  ofl^ensive  conditions,  but  often  they  are,  as  a  matter  of 
fact,  a  source  of  nuisance  in  themselves.  There  is  a  natural  opprobrium 
attached  to  a  region  where  such  works  exist  that  results  in  a  recognized 
deterioration  of  property  values.  The  processes  used  for  the  treatment 
of  sewage  not  infrequently  result  in  odors  that  may  be  objectionable  over 
considerable  areas.     Where  the  treatment  works  are  entirely  covered,  as 


974  SEWAGE  DISPOSAL 

some  kinds  of  works  may  be,  little  or  Jio  Jiiiisance  may  result,  but 
where,  for  example,  the  sewage  is  first  siibmitted  to  putrefaction  in  a 
septic  tank  and  the  septic  effluent  then  sprayed  into  open  air  upon  the 
surface  of  sprinkling  filters,  this  exposure  of  the  atomized  liquid  results 
in  the  liberation  of  odors  that  may  reach  distances  up  to  perhaps  half  a 
mile  from  the  plant,  depending  upon  the  amount  and  character  of 
sewage  treated,  the  local  topography,  prevailing  direction  of  the  wind, 
humidity  in  the  atmosphere,  and  other  conditions. 

Frequently  high  winds  will  carry  the  spray  itself  for  several  hundred 
feet  with  inevitable  bacterial  pollution  of  the  air.  In  the  operation  of 
sprinkling  filters  also  it  has  been  found  that  at  certain  seasons  of  the 


Fig.  130. — Septic  Tank  and  Chemical  Precipitation  Tanks  at  Rochdale,  England. 

year  swarms  of  flies  breed  in  the  porous  beds.  These  are  very  trouble- 
some, if  not  dangerous,  in  the  immediate  vicinity  of  such  works.  In 
considering  the  need  of  sewage  treatment  it  is  proper  to  balance  these 
possible  nuisances  against  those  resulting  from  the  discharge  of  un- 
purified  sewage  into  a  body  of  water.  It  not  infrequently  happens  that 
the  installation  of  sewage  treatment  works  merely  substitutes  one 
nuisance  for  another. 

Nuisances  Caused  by  Trade  Wastes. — It  not  infrequently  happens 
that  the  greatest  nuisance  in  streams  is  due  not  so  much  to  domestic 
sewage  as  to  the  presence  of  trade  wastes  that  may  be  discharged  into 
the  stream  directly,  or  that  may  be  allowed  to  flow  into  the  stream 
through  the  sewers.  For  example,  the  discharge  of  spent  dye  liquors 
may  color  the  water  of  a  stream  for  many  miles ;  petroleum  wastes 
from  gas  works  may  cause  iridescent  films  to  form  upon  the  surface 
of  the  water,  producing  an  unsightly  appearance  and   increasing  the 


COOPERATIVE  SAI^ITATION  975 

odor  directly,  as  well  as  indirectly,  by  excluding  air  from  the  water; 
the  acid  iron  wastes  from  galvanizing  works  may  cause  a  rusty  discolora- 
tion that  not  only  imparts  a  brown  color  to  the  water,  but  paints  the 
rocks  and  submerged  stumps  along  the  shores  for  many  miles.  When 
nuisances  of  this  character  arise  it  is  wise  and  proper  to  install  sewage 
clarification  plants,  and  sometimes  more  elaborate  works,  for  such 
nuisances  cause  real  damage  to 'property  and  to  personal  comfort.  Trade 
waste  pollution  may  interfere  with  the  filtration  of  water  even  more 
than  sewage  itself.  Illustrations  of  this  are  the  paper-mill  pollutions  in 
New  York  State  and  the  acid-iron  wastes  in  Pennsylvania. 


COOPERATIVE   SANITATION 

What  appears  to  be  needed  at  the  present  time  is  some  method  of 
cooperation  by  which  needed  sanitary  reforms  can  be  brought  about 
at  least  expense.  It  is  unbusinesslike  to  compel  the  purification  of  the 
sewage  of  a  large  upstream  city  in  order  to  protect  the  water  supply  of 
a  small  city  lower  down,  if  pure  Avater  can  be  furnished  the  latter  in 
some  better  and  cheaper  way.  Legislation  that  clothes  the  State  authori- 
ties with  power  to  prevent  the  pollution  of  streams  by  sewage,  but  does 
not  give  them  power  to  compel  the  purification  of  water  or  to  control 
pollution  by  trade  wastes,  is  unfortunate.  It  naturally  leads  to  litigation 
rather  than  cooperation,  and  may  retard  rather  than  hasten  necessary 
sanitary  reforms.  If  our  State  authorities  cannot  be  trusted  in  this 
matter  it  may  be  that  a  proper  solution  of  the  difficulty  will  be  found 
in  the  establishment  of  district  boards  similar  to  those  in  England  and 
Germany,  such  boards  having  jurisdiction  over  the  limits  of  particular 
catchment  areas.  In  some  respects  these  natural  hydrographic  boun- 
daries have  advantages  over  artificial  State  boundaries.  In  the  near 
future  also  our  national  government  will  doubtless  take  a  hand  in  the 
matter.  In  whatever  form  the  authority  may  be  constituted  the  idea  of 
cooperation  should  prevail,  and  ironclad  rules  against  stream  pollution 
should  give  way  to  a  rational  distribution  of  the  burden  of  water  puri- 
fication and  sewage  treatment,  and  an  equitable  adjustment  of  cost  made 
between  the  parties  interested,  thus  decreasing  the  total  expense  of  sani- 
tary measures  requiTed  and  utilizing  natural  resources  for  the  purifica- 
tion of  sewage  in  water  as  far  as  this  is  safe. 

If  the  system  of  water  carriage  of  sewage  continues  in  use  the  time 
will  some  day  come  when  the  sewage  of  all  of  our  cities  Avill  be  purified, 
partially  or  completely,  and  all  surface  water  supplies  filtered  It  is 
proper  to  anticipate  this  consummation  as  far  as  onr  means  permit, 
but  meantime  it  is  good  business  and  sound  common  sense  to  spend  our 
.money  first  where  it  will  go  furthest  and  do  the  most  good,  building 


976  SEWAGE  DISPOSAL 

water  filters  and  sewage  treatment  works,  sometimes  one,  sometimes 
both,  as  they  may  be  needed. 

Adequate  remedies  against  stream  pollution  from  the  standpoint  of 
nuisance  have  been  usually  obtained  by  an  appeal  to  the  principles  of 
common  law.  Cases  involving  bacterial  pollution  by  sewage  have  been 
thus  far  too  few  to  establish  definite  precedents.  It  will  be  interesting 
to  see  whether,  in  view  of  our  increasing  population,  and  especially 
the  increasing  growth  of  our  cities,  the  courts  will  ultimately  decide  that 
the  use  of  unfiltered  river  water  as  a  source  of  water  supply  by  riparian 
owners  is  a  reasonable  use  of  the  water. 


THE  RURAL  PROBLEM  OF  SEWAGE  DISPOSAL 

One  of  the  most  difficult  problems  of  modern  sanitation  is  to  secure 
proper  disposal  of  fecal  matter  in  rural  communities,  at  summer  hotels, 
at  temporary  camps  of  laborers,  at  summer  colonies  at  beach  and  moun- 
tain, and  at  individual  houses  in  villages  and  on  the  farm.  It  is  difficult 
because  the  necessary  structures  are  so  small  and  simple  that  they  have 
been  thoughtlessly  constructed,  because  adequate  care  of  the  processes 
is  more  or  less  disagreeable  and  therefore  neglected,  but  chiefly  because 
the  inherent  dangers  have  not  been  understood  or  appreciated. 

One  of  the  most  needed  reforms,  and  one  that  is  happily  making 
progress,  is  that  of  the  protected  privy,  that  is,  one  where  the  fecal 
matter  is  received  in  a  tight  vault  so  constructed  that  the  contents  can- 
not be  reached  by  flies,  insects,  rats,  hens,  or  pigs,  yet  so  ventilated  as 
to  prevent  disagreeable  odors  and  give  opportunity  for  evaporation  of 
liquids.  This  necessitates  the  liberal  use  of  screens  around  the  vault 
and  on  the  windows  and  doors,  and  the  use  of  a  self-closing  cover  for 
the  seat.  The  privy  vault  may  be  constructed  of  concrete,  with  bottom 
and  walls  3  inches  to  6  inches  in  thickness,  or  the  vault  may  be  re- 
placed with  a  tight,  removable  receptacle  of  metal  or  wood  placed  in 
a  screened  compartment.  Properly  constructed  privies  of  this  charac- 
ter may  be  located  near  dwellings,  the  only  conditions  being  those  con- 
trolling offensive  odors,  but  this  presupposes  greater  care  than  is  ordi- 
narily given  to  such  matters.  Preferably,  therefore,  they  should  be 
located  at  some  reasonable  distance  from  dwellings. 

Privies  that  are  not  provided  with  water-tight  vaults,  but  are  so 
arranged  that  the  fecal  matter  falls  upon  the  soil,  may  be  safe,  so  far 
as  water  pollution  is  concerned,  if  the  soil  is  of  proper  character  and 
if  the  privy  is,  sufficiently  removed  from  the  house  well;  but  are  unde- 
sirable for  other  reasons.  No  arbitrary  rules  as  to  the  necessary  mini- 
mum distance  of  a  privy  from  a  well  can  be  laid  down,  as  everything 
depends  upon  the  character  of  the  soil,  the  slope  of  the  ground,  the 


THE  EUEAL  PEOBLEM  OE  SEWAGE  DISPOSAL        977 

elevation  of  the  natural  gromid  water,  and  the  draught  of  water  from 
the  well.  A  distance  of  at  least  25  feet  should  be  secured  with  sandy 
soils,  whenever  possible,  and  preferably  50  feet  or  more.    With  clay  soils, 


Fig.  131. — iNXERiiixTEXT  Sand  Filtration  Bed  at  Beocktox,  Mass. 

liable  to  dry  and  crack,  and  in  limestone  regions,  liable  to  contain 
crevices  in  the  rock,  leaching  privies  should  not  be  used,  as  wells  may 
be  polluted  100  feet  or  even  a  mile  or  more  away. 


Fig.  132. — Filter  Bed  with  Sand  Ridged  for  Wekter  Operatiox  at  Brockton, 
Mass.  The  ice  sheet  rests  on  the  ridges.  The  photograph  shows  the  accumulation 
of  suspended  matter  during  the  vrinter. 

Cesspools  are  holes  dtig  in  the  grotind  to  receive  not  only  fecal 
matter,  but  also,  perhaps,  sink  wastes  and  water-closet  discharges.  They 
are  often  lined  with  loose  stones  to  prevent  caving,  but  this  permits  the 


978  SEWAGE  DISPOSAL 

liquids  to  leach  into  the  soil.  When  the  soil  is  sandy  there  is  no  objec- 
tion to  this  method  of  disposal;  in  fact,  it  is  like  the  method  of  sub- 
soil disposal  previously  described,  except  that  the  sewage  is  discharged 
into  the  soil  below  the  depth  where  the  soil  bacteria  are  at  work.  This 
may  be  an  important  difference,  however,  and  the  oxidation  of  the  dis- 
solved organic  matter  proceeds  by  a  slow  and  incomplete  process.  Leach- 
ing cesspools,  however,  should  not  be  located  near  wells  used  for  drink- 
ing water  supplies.  In  sandy  soils  the  danger  of  bacterial  contamination 
is  small  if  the  distance  is  more  than  25  feet,  but,  even  so,  the  idea  of 
infiltration  of  sewage  into  a  well  is  repugnant,  and  often  the  water  may 
be  so  tainted  as  to  have  a  disagreeable  odor,  even  when  analysis  shows 
it  to  be  bacterially  safe. 


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Fig.  133. — Discharge  of  Sewage  upon  a  Filter  Bed  at  Brockton,  Mass. 

Ordinarily  leaching  cesspools  should  not  be  constructed  in  clay  soils 
or  in  limestone  regions,  for  they  are  liable  to  seriously  pollute  the 
ground  water  and  are  almost  sure  to  overflow.  If  cesspools  are  neces- 
sary under  such  conditions  they  should  be  made  water-tight  and  treated 
as  septic  tanks  and  the  effluent  taken  care  of  by  subsurface  irrigation  or 
some  form  of  land  treatment. 

In  cesspools  the  organic  matter  undergoes  septic  action  and  the 
amount  of  sludge  that  accumulates  is  often  small.  Nevertheless,  clean- 
ing is  necessary  at  intervals  in  the  case  of  all  cesspools.  The  disposal 
of  the  contents  is  one  of  the  most  troublesome  questions  connected  with 
this  form  of  sewage  disposal.  The  common  method  is  to  spread  it  upon 
the  land  as  a  topdressing.  The  work  is  apt  to' be  done  in  the  winter, 
when  other  farm  work  is  not  pressing,  and  not  infrequently  when  the 
ground  is  frozen.  Thus  opportunity  is  given  for  fecal  bacteria  of  human 
origin  to  be  washed  into  a  well  or  some  public  water  supply.     If  spread 


THE  EUEAL  PEOBLEM  OF  SEWAGE  DISPOSAL        979 

on  the  ground  during  the  summer  flies  liave  access  to  it.  If  used  for 
fertilizer  for  crops  eaten  raw,  as  celery  or  lettuce,  opportunity  is  offered 
for  transmission  of  infection  by  such  foods.  The  only  proper  method  of 
disposal  for  cesspool  sludge  is  by  burial  or  disinfection.  In  laborers' 
camps^  and  in  army  camps,  disposal  of  fecal  matter  by  cremation  is 
practiced  with  advantage. 

In  the  South,  where  hook-worm  disease  is  prevalent,  the  scattering 
of  human  fecal  matter  upon  the  surface  of  the  ground  is  one  of  the 
greatest  elements  of  danger.  The  danger  of  transmission  of  infection 
by  flies  from  fecal  matter  to  food  is  likewise  greater  in  the  South,  as 
the  warm  season  is  longer,  so  that  greater  care  needs  to  be  exercised  in 
the  construction  and  care  of  protected  privies  than  in  the  ISTorth. 

REFERENCES 

1890-1910. — Annual  Reports  of  the  Massachusetts  State  Board  of 
Health.  (Summary  of  Results  Obtained  at  the  Lawrence  Experiment  Sta- 
tion During  Twenty-one  Years  Is  Given  in  the  Report  of  1908.) 

1905-1910. — Contributions  from  the  Sanitary  Research  Laboratory  of 
the  Massachusetts  Institute  of  Technology.  Eight  volumes,  containing 
papers  by  Professors  Sedgewick,  Winslow,  Phelps,  and  others. 

1908. — Dunbar:  "Principles  of  Sewage  Treatment."  Translated  by 
H.  T.  Calvert.     Charles  Griffin  &  Co.,  Ltd.,  London. 

1910. — Kinnicutt,  Winslow,  and  Pratt:  "Sewage  Disposal."  John 
Wiley  &  Sons,  New  York. 

1910. — Schmeitzner,  Rudolf:  "Clarification  of  Sewage,"  translated  by 
A.  E.  Kimberly.    Engineering  News  Publishing  Company,  New  York. 

1911. — Kershaw,  G.  Bertram:  "Modern  Methods  of  Sewage  Purifica- 
tion."    Charles  Griffin  &  Co.,  Ltd.,  London. 

1912. — Eisner,  Alexander:  "Sewage  Sludge  Treatment."  Translated 
by  Kenneth  Aflen.     McGraw-Hill  Book  Co.,  New  York. 

1912.— Fufler,  G.  W. :  "Sewage  Disposal."  McGraw-Hill  Book  Co., 
New  York. 

1912.— Ogden,  Henry  N.,  and  Cleveland,  H.  B. :  "Practical  Methods 
of  Sewage  Disposal." 

1915. — Metcalf  and  Eddy :  "American  Sewerage  Practice,"  3  volumes. 
The  third  volume  treats  of  sewage  disposal. 

1916. — Follwell,  A.  Prescott :  "Sewerage."  Seventh  edition.  John 
Wiley  &  Sons,  New  York. 

For  references  to  recent  works  for  the  treatment  of  sewage  see  files  of 
Engineering  News  and  Engineering  Record. 


SECTION   Yin 
REFUSE  DISPOSAL 

By  George  C.  Whipple 
Professor  of  Sanitary  Engineering  in  Harvard  University 

The  general  term  "refuse"  is  applied  to  all  of  the  solid  waste  ma- 
terial not  carried  by  the  sewers,  such  as  ashes,  rubbish,  garbage,  street 
sweepings,  manure,  and  dead  animals.  The  quantity  of  this  waste 
material  that  has  to  be  gotten  rid  of  in  a  city  is  very  large.  For  exam- 
ple, in  the  Borough  of  Manhattan,  New  York  City,  the  ashes  amount 
to  about  1,200  pounds  per  capita  per  year,  the  rubbish  100  pounds,  tho 
street  sweepings  300  pounds,  and  the  garbage  200  pounds,  the  total 
amount  of  refuse  being,  in  round  numbers,  a  ton  per  capita  per  year. 
In  smaller  cities  the  per  capita  quantities  of  collected  refuse  are  less 
than  half  of  this,  sometimes  considerably  less.  The  amount  of  garbage 
alone  varies  from  less  than  100  to  upward  of  200  pounds  per  capita 
per  year.  Both  the  quantity  and  character  of  the  refuse  vary  with  the 
seasons,  the  maximum  amount  of  ashes  occurring  in  the  winter  and  the 
maximum  amount  of  garbage  in  the  summer.  This  fact  has  an  im- 
portant bearing  on  the  problem  of  ultimate  disposal. 

Ashes  weigh  from  900  to  1,200  pounds  per  cubic  yard,  garbage  from 
900  to  1,100  pounds,  street  sweepings  from  700  to  1,800  pounds,  and 
rubbish  from  150  to  250  pounds.  The  following  figures  serve  to  indi- 
cate approximately  the  constituents  of  the  principal  classes  of  refuse : 

CONSTITUENTS  OF  CITY  REFUSE. 


Water 

Volatile 
Matter 

Ash 

Carbon 

Heat  Units 

per  Pound 

of  Refuse 

B.  T.  U. 

7-25  per  cent. 
70-80  per  cent. 

5-15  per  cent. 
35-45  per  cent. 

8-10  per  cent. 
15-25  per  cent. 
40-65  per  cent. 
20-30  per  cent. 

50-60  per  cent. 

5-15  per  cent. 

5-15  per  cent. 
25-95  per  cent. 

18-25  per  cent. 

4-8   per  cent. 

15-40  per  cent. 

18-25  per  cent. 

3,700 

2,000 

6,000 

Street  sweepings 

4,000 

The  refuse  problem  is  to  a  slight  extent  a  hygienic  one,  but  it  is  more 
a  problem  of  economy,  convenience,  and  general  cleanliness.  Bad  smells 
from  fermenting  garbage  do  not  directly  injure  the  public  health,  yet 
they  are  an  offense,  and  their  elimination  is  an  important  matter. 
Ashes  and  street   dust  may   irritate  the   eyes,  nose,  and  throat   and 

981 


983 


EEFUSE  DISPOSAL 


predispose  to  bacterial  infection.  Accumulating  rubbish  is  not  only  un- 
sightly, but  may  provide  conditions  favorable  for  mosquito  breeding, 
while  accumulating  manure  may  breed  flies.  Garbage  attracts  flies  and 
may  breed  them  if  the  cans  are  left  uncleaned  from  week  to  week,  but 
ordinarily  garbage  does  not  stand  uncollected  long  enough  to  give  oppor- 
tunity for  the  larvae  to  hatch. 

There  are  two  general  methods  of  collection  and  disposal  of  city 
refuse:  the  mixed  system  and  the  separate  system.     With  the  mixed 


7bF/7/ 


'vSwi/ 


i^or  fer/-//izer 

Fig.  134. — Digestion  Process  of  Garbage  Reduction. 
(Boston  Development  and  Sanitary  Company.) 

system,  which  is  the  one  most  generally  used  in  Europe,  all  of  the 
refuse,  ashes,  garbage,  and  rubbish  is  put  together  by  the  householder  in 
a  single  can,  conveyed  by  wagon  to  the  disposal  plant,  where  it  is  all 
burned  together  and  the  organic  matter  thus  destroyed.  The  com- 
bustible matter  in  the  rubbish  and  the  unburned  coal  in  the  ashes  are 
usually  sufficient  to  evaporate  the  water  in  the  garbage,  so  that  the 
material  is  self-consuming.  This  method  is  known  as  incineration,  or 
cremation,  or  destruction.  With  the  separate  system  the  garbage,  rub- 
bish, and  ashes  are  kept  separate  by  the  householder  and  collected  in 
separate  wagons  and  disposed  of  in  different  ways.    The  ashes  are  used 


983 


^84  REFUSE  DISPOSAL 

for  filling  low  land,  the  rubbish  carried  to  the  dump,  and  the  garbage 
taken  to  sea  and  dumped  or  buried,  or  fed  to  hogs,  or  taken  to  a  re- 
duction plant,  where  it  is  cooked  and  treated  for  the  recovery  of  fats 
and  other  products. 

The  separate  system  is  commonly  used  in  America,  but  with  nume-r- 
ous  combinations  of  processes  of  collection  and  disposal.  Whichever 
method  of  disposal  is  adopted  determines  the  manner  of  collection  and 
the  treatment  of  the  refuse  by  the  householder.  The  choice  of  the 
system  to  be  used  is  one  to  be  determined  for  each  community,  largely 
on  the  basis  of  cost.  Generally  speaking,  an  incineration  plant  entails 
a  greater  initial  outlay  than  a  reduction  plant.  Its  products  are  ashes 
and  steam.  The  ashes  transported  are  commonly  used  for  filling  near 
the  plant;  the  steam  is  used  for  power  to  run  the  works,  and  the  excess 
steam  is  sold  or  converted  into  electricity  and  conveyed  to  places  where 
it  can  be  utilized  to  advantage.  In  cities  where  power  is  expensive 
the  receipts  for  the  sale  of  power  may  be  sufficient  to  throw  the  balance 
in  favor  of  this  method  of  disposal.  Where  power  is  cheap,  however, 
the  opposite  may  be  the  case  and  the  reduction  process  prove  the  cheaper. 
With  the  reduction  process  the  salable  products  are  grease  and  tankage. 
The  former  is  sold  for  soap  manufacture,  and  the  latter,  which  con- 
sists of  the  solid  particles  of  the  cooked  garbage,  is  pressed,  dried,  and 
ground,  and  used  as  a  filler  for  fertilizers.  As  time  goes  on  other  useful 
products  are  likely  to  result  from  tliis  process,  as  the  materials  wasted 
or  sold  contain  much  sugar  and  proteid  bodies. 

Incineration  Plants. — There  are  two  general  types  of  destructors. 
The  mutual  assistance  type,  where  there  are  several  grates  and  divided 
ash  pits,  the  products  of  combustion  commingling  above,  thus  combining 
several  furnaces  into  one,  and  the  separate  unit  type. 

The  temperature  of  combustion  varies  from  about  1,200°  to  2,000° 
F.  and  the  capacity  is  from  1,200  to  1,500  pounds  of  mixed  refuse  per 
day  for  each  square  foot  of  grate  surface.  Each  pound  of  mixed  refuse 
is  capable  of  evaporating  from  one  to  two  pounds  of  water.  So-called 
cremation  plants  are  operated  at  lower  temperatures  and  are  less  satis- 
factory. 

The  best  illustration  of  an  incinerator  in  this  country  is  the  one 
recently  constructed  at  Milwaukee.  This  was  designed  by  Dr.  Eudolph 
Hering,  and  a  description  of  it  may  be  found  in  the  Engineering  News 
for  July  10,  1910.  It  has  a  capacity  of  300  tons  of  mixed  refuse  per 
day.  The  Milwaukee  incinerator  receives  street  sweepings  and  manure 
as  well  as  ashes,  rubbish,  and  garbage.  The  manure  has  been  found 
fully  as  difficidt  to  burn  as  the  garbage,  and  on  general  principles  it 
would  appear  to  be  wasteful  to  dispose  of  it  in  that  way.  With  a  well- 
arranged  incinerator  there  are  practically  no  objectionable  odors  and 
very  little  disagreeable  smoke. 


EEFUSE  DISPOSAL 


985 


Reduction  Plants. — This  method  of  garbage  disposal  is  used  in  many 
of  our  largest  American  cities,  including  New  York,  Boston,  Buffalo,  the 
plants  as  a  rule  being  owned  and  operated  by  private  companies  under 
contract  with  the  city.  Eecently  an  excellent  plant  of  the  reduction  type 
has  been  constructed  by  the  city  of  Columbus  and  is  now  operated  by  the 
city.    A  description  of  this  plant  may  be  found  in  the  Engineering  Rec- 


Oarba^e  Bins 


Cans 


Boft/es 


Sor/er 


Cbne^ffnser 


tteafer 


>  Separator 


T"^ 


Tank  -Pu/i^ 


-^2U      So/icf 
^  yVas/es 


Conveyor 


^Jfea/rr 


£xfracf/orj 
TbryA 


Water  from 

&or/yoffe  (^o 

setver) 


Grease 
and 
So/^ent 


\ 


Muc/Dro/T) 


\Sfeam 


Tankage 


Screen 


Sf/// 


*■  P/cker 


(?r/ncfer 


Sforape         Baffler 


to  cfc/mp 


Bones,  etc. 


V\ 


Grease         Ibnkcf^e 

So/e/  for  So/d  as 

Soaps  ana  Cor>c//es    Ferf/'/izer 

Fig.  136. — Cobwell  Process  of  Garbage  Reduction,  New  Bedford,  Mass. 


ord  of  ISTovember  ID,  1910.  When  the  garbage  reaches  a  plant  of  this 
type  it  is  sorted  to  remove  foreign  substances,  such  as  tin  cans,  glass 
bottles,  etc.,  and  conveyed  to  a  series  of  digesters,  where  it  is  cooked  for 
from  six  to  ten  hours  under  pressure  of  about  60  pounds.  It  then 
passes  through  presses  which  separate  the  water  and  fats  from  the  solid 
part,  called  tankage.  The  water  and  grease  are  allowed  to  pass  through 
settling  tanks,  where  the  grease  is  skimmed  off  the  top.  The  water  flows 
away  to  the  sewer  or  is  evaporated,  and  the  solids  added  to  the  tankage. 
The  latter  is  sometimes  treated  for  fat  recovery  by  the  use  of  hot  naphtha. 


986  EEFUSE  DISPOSAL 

Ultimately  the  tankage  is  ground  and  dried  and  used  as  a  filler  for 
fertilizers.  The  per  cent,  of  grease  recovered  may  amount  to  from  1  to 
3  per  cent,  and  the  marketable  tankage  to  about  20  per  cent,  of  the 
garbage.  Unless  a  plant  of  this  type  is  well  designed  and  carefully  man- 
aged offensive  odors  will  result,  but  these  can  be  almost  completely  done 
away  with  if  proper  precautions  are  taken. 

Feeding  Garbag'e  to  Hogs, — In  many  small  cities,  especially  those  of 
New  England,  the  garbage  is  fed  to  hogs.  This  requires  frequent  col- 
lection and  careful  management  at  the  piggery.  If  the  garbage  is 
sterilized  with  steam,  and  if  the  feed  is  supplemented  with  grain,  and 
the  garbage  feed  stopped  a  few  weeks  before  the  hogs  are  killed,  there 
seems  to  be  no  sanitary  objection  to  this  method,  while  it  may  be  a 
profitable  one  on  account  of  the  large  food  value  of  the  garbage. 

Collection  of  Garbage. — From  a  sanitary  standpoint,  and  even  from 
the  standpoint  of  nuisance,  the  problem  of  garbage  collection  is  even  a 
more  difficult  one  than  that  of  garbage  disposal.  A  strong  argument  in 
favor  of  the  incinerator  method  is  that  the  method  of  mixed  collection 
can  be  carried  on  with  less  nuisance  than  separate  collection.  When 
garbage  is  mixed  with  the  ashes  in  a  single  can  the  water  of  the  garbage 
is  absorbed  by  the  ashes,  fewer  flies  are  attracted  to  it,  and  the  odor 
is  reduced.  The  absorption  of  water  by  the  ashes  also  tends  to  reduce 
the  dust  nuisance.  Mixed  collection  is  also  more  economical,  as  fewer 
carts  are  required  and  collections  need  not  be  as  frequently  made.  Much 
depends,  however,  upon  local  conditions. 

Garbage  disposal  plants  are  best  located  near  the  outskirts  of  the 
city,  where  no  nuisance  will  result.  This  ordinarily  involves  a  long 
haul.  If  favorable  opportunities  exist  for  dumping  ashes  within  the 
limits  of  a  short  haul  the  separate  collection  of  refuse  may  prove  the 
cheaper.  At  Minneapolis  the  householders  are  required  to  wrap  each 
day's  garbage  in  paper.    This  method  is  said  to  be  very  satisfactory. 

REFERENCES 

1905. — Hering,  Rudolpli:  "Review  of  General  Practice  of  Disposal  of 
Municipal  Refuse."  Transactions  American  Society  of  Civil  Engineers, 
Yol.  LIV,  Part  E,  p.  263. 

1906. — Parsons,  H.  deB. :  ''Disposal  of  Municipal  Refuse."  John 
Wiley  &  Sons,  New  York. 

1906. — ^Yenable,  W.  M. :  "Garbage  Crematories  of  the  United  States." 
John  Wiley  &  Sons,  New  York. 

1910.— Morse,  W.  P.:  "Collection  and  Disposal  of  Wastes."  Pub- 
lished by  the  Municipal  Journal,  New  York. 

1911. — Greeley,  Samuel  A. :  "Investigations  for  Municipal  Refuse 
Disposal."    Proceedings  New  Jersey  Sanitary  Association,  November,  1911. 


SECTION  IX 
VITAL  STATISTICS 

The  Registration  of  Births^  Deaths,  and  Marriages,  and  the  Reporting 
of  Notifiable  Diseases;  the  Resulting  Records  and  Derived  Statistics; 
and  Their  Legal,  Social,  and  Public  Health  Uses. 

By  JoHK  W.  Teask 
Assistant  Surgeon  General,  United  States  Public  Health  Service 

Statistics  have  suffered  in  reputation  because  of  the  seeming  truth 
of  the  trite  statement  that  one  can  prove  anything  by  figures.  In  reality 
figures  are  but  evidence  upon  which  conclusions  may  be  based.  If  the 
evidence  is  faulty  and  the  faults  are  not  perceived,  errors  in  judgment 
may  result.  But  this  is  true  of  all  evidence  upon  which  opinions  are 
based  and  is  no  more  true  of  figures  and  statistics  than  it  is  of  other 
kinds  of  evidence. 

Statistics  are  derived  from  the  collection  and  numerical  classifica- 
tion of  observations  relating  to  certain  facts  or  events.  They  are  usually 
limited  to  the  systematic  collection  and  classification  of  data  relating 
to  relatively  large  classes  of  events.  In  the  making  of  statistics  the 
first  and  essential  step  is  the  recording  of  observations.  After  the 
observations  have  been  noted  a  numerical  compilation  of  their  fre- 
quency or  of  the  frequency  of  certain  of  their  conditions  or  attributes 
is  possible.  The  derived  statistics,  being  but  a  numerical  classification 
or  analysis  of  the  recorded  events,  depend  primarily  for  their  usefulness 
upon  the  accuracy  of  the  original  records  of  facts.  They  depend  sec- 
ondarily upon  the  accuracy  of  the  statistical  classification  and  compila- 
tion. 

The  original  notation  of  facts  and  of  the  occurrence  of  events  is 
usually  secured  in  one  of  two  ways,  by  enumeration  or  by  registration. 
Observations  relating  to  the  population  are  made  for  example  by  enumer- 
ation at  the  decennial  censuses.  The  census  enumerators  go  from  house 
to  house  and  secure  certain  information  regarding  each  individual.  The 
enumerators  are  the  observers  who  secure  the  original  data.  Statistics 
of  population  are  made  by  the  classification  of  .the  information  thus  ob- 
tained and  the  numerical  compilation  of  the  frequency  of  certain  at- 
tributes. 

On  the  other  hand,  the  notation  of  facts  relating  to  deaths  is  secured 

987 


988  VITAL  STATISTICS 

by  registration.  For  each  individual  who  dies  there  is  registered  with 
an  official  known  as  a  registrar  certain  information  regarding  the  de- 
ceased and  the  cause  and  time  of  death.  Here  the  observers  who  record 
the  original  data  are  the  physicians,  members  of  families,  and  under- 
takers. From  the  classification  and  compilation  of  the  information  thus 
recorded  mortality  statistics  are  made.  Statistics  of  population  depend 
for  their  accuracy  upon  the  correctness  of  the  records  made  by  the 
enumerators  and  mortality  statistics  upon  the  accuracy  of  the  informa- 
tion registered  in  death  certificates. 

The  statistical  method  is  in  itself  dependable,  although  it  is  true  that 
statistics  may  be  vitiated  by  the  use  of  inaccurate  or  incomplete  data 
as  a  basis  or  of  faulty  methods  in  classification  and  compilation.  Oon- 
clusions  drawn  from  statistics  by  those  who  attempt  to  use  them  may 
be  quite  erroneous,  but  this  is  more  often  due  to  the  limitations  of  the 
user  than  to  the  limitations  of  the  statistics.  The  most  common  error 
in  the  use  of  statistics  is  perhaps  the  comparing  of  numerical  statements 
or  ratios  which  are  too  dissimilar  to  allow  of  comparison. 

To  make  dependable  statistics  the  original  observations  and  records 
from  which  they  are  derived  must  be  true  and  accurate,  and  the  classifi- 
cation, compilation,  and  analysis  must  be  done  by  competent  individuals. 
The  value  of  statistics  when  thus  handled  is  daily  demonstrated  in  vari- 
ous economic  and  commercial  activities. 


VITAL  STATISTICS 

Definition. — Vital  statistics  may  be  defined  as  statistics  relating  to 
the  life  histories  of  communities  or  nations.  They  pertain  to  those 
events  which  have  to  do  with  the  origin,  continuation,  and  termination 
of  the  lives  of  the  inhabitants.  They  commonly  include  statistics  of 
births,  marriages,  deaths,  the  occurrence  of  disease,  immigration  and 
emigration,  and  the  conditions  attending  these  events. 

Guilfoy  has  given  a  descriptive  definition  which  in  slightly  abbre- 
viated form  is  that  vital  statistics  are  "the  numerical  registration  and 
tabulation  of  population,  marriages,  births,  diseases,  and  deaths,  coupled 
with  analyses  of  the  resulting  numerical  phenomena."  ^ 

Development. — Vital  statistics  are  not  a  thing  of  recent  origin.  Their 
development  to  their  present  form,  however,  is  comparatively  modern. 
The  Egyptians,  Greeks,  and  Eomans  made  census  enumerations.  Some 
of  the  ancients,  notably  the  Eomans,  required  also  the  registration  of 
births  and  deaths.  The  statistical  treatment  of  the  records  was,  how- 
ever, comparatively  limited.     During  the  last  century  and  a  half,  and 

*  Guilfoy,  W.  H.:  "Vital  Statistics  in  the  Promotion  of  Public  Health," 
N.  Y.  Med.  Jour.,  Nov.  5,  1910. 


POPULATION  STATISTICS  989 

more  particularly  the  last  50  years,  the  treatment  of  vital  statistics  has 
been  undergoing  a  rapid  evolution.  In  their  present  developed  form 
they  give  a  fund  of  useful  information  otherwise  unobtainable.  They 
have  become  an  essential  to  every  well-organized  community  and  nation. 
They  give  a  composite  picture  of  the  life  history  of  a  people  which  can 
be  secured  in  no  other  way.  They  furnish  a  means  of  comparing  the 
life  history  of  one  community  or  people  with  that  of  others  and  of  the 
present  with  the  past. 

Based  upon  Population. — All  vital  statistics  are  based  upon  the  pop- 
ulation. The  frequency  of  births,  marriages,  sickness,  and  deaths  is 
expressed  in  terms  of  the  population,  usually  as  rates  giving  the  number 
for  each  1,000  inhabitants  or  class  of  inhabitants.  In  comparing  dif- 
ferent communities  or  different  periods,  births,  marriages,  deaths,  and 
the  incidence  of  disease  must  be  based  upon  a  common  unit  of  population. 
The  first  requisite  to  useful  vital  statistics  is  statistics  of  population  show- 
ing the  number  of  inhabitants,  classified  according  to  age,  sex,  nativity, 
race,  and  occupation.  It  would  be  desirable,  if  possible,  to  have  also  a 
classification  according  to  economic  status,  as  birth,  sickness,  marriage, 
and  mortality  rates  frequently  varying  with  the  incomes  of  individuals  or 
households.  An  understanding  of  population  statistics  is  therefore  the 
primary  essential  to  the  comprehension  or  use  of  vital  statistics,  and  sta- 
tistics of  population  will  be  first  considered. 


POPULATION  STATISTICS 

Source  of  Data. — The  principal  source  of  information  regarding  pop- 
ulation under  existing  conditions  is  a  census  enumeration.  For  the 
United  States  these  enumerations  are  made  every  10  years.  The  last 
census  was  taken  as  of  April  15,  1910.  In  the  United  States  a  census 
has  been  taken  every  10  years  since  1790,  in  Great  Britain  every  10  years 
since  1801.  In  taking  a  census  it  is  desirable  in  so  far  as  possible  to 
take  it  at  a  time  when  the  greatest  number  of  people  will  be  at  their 
usual  homes.  A  midwinter  census  would  find  many  people  absent  from 
the  Northern  States  and  an  unusual  number  in  southern  winter  resorts. 
A  midsummer  census  would  find  an  unusual  number  at  the  seashore  and 
at  other  summer  resorts.  A  number  of  the  States  take  a  census  midway 
between  the  United  States  decennial  censuses,  so  that  they  have  an 
enumeration  of  the  population  every  five  years. 

As  the  only  source  of  definite  information  as  to  population  is  the 
census  enumeration,  and  as  the  population  is  continually  changing, 
in  most  cases  increasing,  it  is  necessary  to  make  estimates  of  the  popu- 
lation for  the  periods  between  the  census  enumerations  upon  which  to 
base  rates  for  the  various  vital  events  and  especially  for  the  accurate 


990  VITAL  STATISTICS 

(computation  and  exjoression  of  marriage,  birth,  death,  and  sickness  rates, 

Nature  of  Census  Information. — The  taking  of  a  census  consists 
usually  of  more  than  a  mere  enumeration  of  all  persons  living  at  the 
time  the  census  is  taken.  It  includes  the  recording  of  certain  informa- 
tion regarding  each  individual.  In  taking  the  1910  United  States  census 
the  following  information  relating  to  each  individual  yvas  recorded  by 
States,  counties,  and  townships,  villages  or  cities :  Name ;  address ;  sex ; 
color  or  race;  age  at  last  birthday;  whether  single,  married,  widowed, 
or  divorced;  number  of  years  of  present  marriage;  mother  of  how  many 
children,  total  number  born,  number  now  living;  individual's  place  of 
birth,  place  of  birth  of  his  father  and  mother;  year  of  migration  to  the 
United  States;  whether  naturalized  or  alien;  whether  able  to  speak 
English,  and  if  not,  the  language  spoken;  the  individual's  occupation, 
the  kind  of  work  done  and  the  industry  or  business  in  which  employed ; 
whether  an  employer,  employee,  or  working  on  ovsm  account;  whether 
employed  or  out  of  work  April  15;  whether  able  to  read  and  write; 
whether  attending  school ;  whether  he  owns  the  home  in  which  he  lives ; 
whether  a  survivor  of  the  Union  or  Confederate  Army  or  Navy ;  whether 
blind  in  both  eyes,  or  deaf  and  dumb. 

From  the  information  thus  obtained  the  statistics  of  population  are 
made.  By  the  classification  and  numerical  compilation  of  this  data  it  is 
possible  to  ascertain  the  composition  and  distribution  of  the  population 
as  to  sex,  color  or  race,  age,  marital  status,  fecundity,  nativity,  occupa- 
tion, literacy,  blindness,  and  deaf -mutism. 

Sources  of  Error  in  Census  Enumerations. — A  certain  number  of  indi- 
viduals will  be  enumerated  both  at  the  place  where  they  happen  to  be  and 
at  their  proper  residences.  A  few  will  be  missed  entirely.  However, 
the  degree  of  error  thus  caused  will  not  be  great. 

The  margin  of  error  in  the  securiiig  of  ages  is  greater.  The  age 
recorded  is  customarily  intended  to  be  the  age  in  years  at  the  last  birth- 
day. The  ages  given  for  children  under  5  years  old  are  likely  not  to  be 
accurate  due  to  the  tendency  to  give  the  age  of  a  child  between  6  and  12 
months  of  age  as  1  year  old  and  that  of  a  child  between  1  and  2  years 
old  as  3  years  of  age.  This  tendency  to  give  the  age  at  the  next  birthday 
persists  up  to  about  the  fifth  year,  although  it  is  perhaps  greatest  during 
the  first  and  second  years.  To  avoid  the  error  thus  arising,  the  United 
States  census  records  the  ages  of  children  under  two  years  of  age  in  years 
and  months.  For  exam^Dle,  a  child  6  months  of  age  is  recorded  as  six- 
twelfths  of  a  year  old  and  a  child  of  17  months  of  age  as  1  5/12  years 
old. 

Women  15  to  20  years  of  age  are  prone  to  give  their  ages  as  between 
20  and  25  years.  Adults  over  25  years  of  age  frequently  do  not  know 
their  exact  ages  and  are  prone  to  approximate  their  ages  as  being  30 
or  40  or  50  years,  and  to  a  less  extent  at  35  or  45  or  55  years.    The  result 


POPULATION  STATISTICS 


991 


is  that  there  is  at  each  census  an  exaggerated  number  of  ages  of  30,  40, 
50  years,  and  also  a  lesser  exaggeration  of  ages,  35,  45,  55,  and  65  years. 
Individuals  over  80  years  of  age  are  prone  to  give  their  ages  as  greater 
than  they  really  are. 

There  is  also  a  considerable  margin  of  error  in  the  recording  of  occu- 
pation. This  is  due  largely  to  an  imperfect  understanding  of  what  is 
wanted  and  to  the  multiplicity  of  occupations  and  a  lack  of  knowledge 
as  to  their  proper  designation. 

Fluctuation  in  Population. — Populations  are  constantly  changing. 
Individuals  are  continually  being  added  by  immigration.  In  the  United 
States,  and  more  particularly  in  some  sections  of  the  United  States,  con- 
siderable numbers  are  annually  being  added  in  this  way.  Immigration 
is  also  an  important  factor  in  the  growth  of  population  in  certain  South 
American  countries,  South  Africa,  Xew  Zealand,  Australia,  and  Canada. 

Populations  suffer  a  continuous  diminution  by  reason  of  emigra- 
tion.    This  is  especially  true  of  some  European  countries. 

Migrations  not  only  may  affect  the  population  of  a  country  as  a 
whole,  but  also  may  alter  the  distribution  of  people  within  a  country. 
There  is  in  many  countries  a  constant  movement  of  people  from  rural 
localities  to  the  cities  and  from  one  locality  to  another. 

All  populations  are  also  being  increased  by  births  and  suffering 
losses  by  deaths.  The  rate  of  change,  however,  resulting  from  births 
and  deaths  is  usually  comparatively  constant  or  alters  gradually,  while 
the  changes  due  to  migrations  may  be  exceedingly  irregular.  The  in- 
crease in  the  population  caused  by  the  excess  of  births  over  deaths  is 
known  as  the  natural  increase.  A  country  in  which  the  birth  and  death 
rates  are  equal  and  in  which  the  factor  of  migration  is  negligible  will 
have  a  fixed  population. 

The  increase  of  population  in  certain  countries  is  shown  by  the  fol- 
lowing table : 

Showing  growth  of  population  of  certain  countries  in  millions,  1800  to  1910 


France 

Great  Britain  and  Ireland 

Russia  in  Europe 

Austria 

Italy 

Spain 

Belgium 

Sweden ; 

United  States , 


1800 


27 
16 
35 
25 
17 
10 

2 

5 


32 
24 
45 
29 
21 
11 
3 
2 
12 


I860 


36 
29 
68 
34 
25 
15 
4 
3 
31 


1890 


38 
38 
92 
40 
30 
17 
6 
4 
62 


39 
44 

49 
34 
19 

7 

5 

92 


Estimates  of  Population. — The  frequency  of  births,  marriages,  or 
deaths  is  usually  expressed  as  the  number  occurring  during  the  calendar 
year  per  1,000  population.     The  figures  thus  given  are  known  as  the 


993  VITAL  STATISTICS 

birth,  marriage,  or  death  rates,  and  are  computed  upon  the  mean  popu- 
lation— that  is,  the  number  of  inhabitants  estimated  to  have  existed  at 
tlie  middle  of  the  year,  July  1.  These  estimates  are  necessary  for  all 
dates  except  those  on  which  census  enumerations  are  made.  For  the 
making  of  estimates  there  are  two  principal  methods  commonly  used, 
known,  respectively,  as  the  arithmetical  and  the  geometrical  methods. 
In  each  method  the  populations  at  the  last  two  census  enumerations 
form  the  known  quantities  from  which  the  estimates  are  derived. 

Arithmetical  Method. — ^In  the  arithmetical  method  it  is  assumed 
that  the  increase  or  decrease  in  population  which  occurred  between  the 
last  two  census  enumerations  took  place  in  equal  amounts  during  each 
intercensal  year  (the  years  between  two  census  enumerations)  and  will 
continue  to  take  place  annually  in  like  numbers  until  the  next  census 
shall  have  been  taken.  Thus,  given  a  city  which  had  a  population  of 
50,000  at  the  1900  census  (June  1,  1900)  and  one  of  61,850  at  the  1910 
census  (Apr,  15,  1910),  the  increase  during  the  intercensal  period  (9 
years  and  10^/2  months)  would  be  11,850  and  the  annual  increase  accord- 
ing to  the  arithmetical  method  would  be 

61,850-50,000 

-^ K^ ,  or  1,200 

If  it  is  desired  to  estimate  the  population  as  of  July  1,  1906,  for  the 
purpose  of  calculating  annual  rates,  this  is  done  by  adding  to  the  popu- 
lation as  it  existed  June  1,  1900,  the  sum  of  1,200  for  each  year  inter- 
vening between  the  date  of  enumeration  (June  1,  1900)  and  the  date 
for  which  the  estimate  is  to  be  made  (July  1,  1906).  There  being  6 
years  and  1  month  between  these  dates,  the  calculation  would  be 

50,000  +  (6J2  X  1,200)=57,300. 

This  same  annual  increase  is  also  assumed  to  occur  until  the  next 
census  shall  have  been  taken,  so  that  if  it  is  desired  to  estimate  the 
population  for  July  1,  1914,  take  the  population  at  the  preceding  census 
(Apr.  15,  1910)  and  add  1,200  for  each  year  intervening  between  its 
enumeration  and  the  date  for  which  an  estimate  is  desired  (July  1, 
1914).  There  being  4  years  and  2^  months  between  these  dates,  the 
calculation  would  be 

61,850  +  (4^^^  X  1,200)=66,900. 

This  method  assumes  the  same  amount  of  increase  each  year  and 
is  analogous  to  the  calculation  of  simple  interest.  It  does  not  take 
into  account  the  fact  that  with  the  annual  increase  in  population  the 
number  of  persons  of  marriageable  age  and  therefore  the  number  of 
married  persons  will  be  greater  each  year  and  consequently  the  number 
of  births.  The  growth  due  to  natural  increase  (the  excess  of  births  over 
deaths)  is  analogous  to  the  increment  of  compound  interest,  and  where 


POPULATION  STATISTICS  993 

this  factor  (the  natural  increase)  is  the  principal  one  affecting  the  popu- 
lation growth  estimates  of  population  made  by  the  arithmetical  method 
are  unsatisfactory,  and  especially  so  where  the  estimate  is  made  for  a 
date  several  years  away  from  a  census  enumeration.  Where  the  excess 
of  births  over  deaths  is  the  controlling  factor  in  population  growth  the 
geometrical  method  of  making  estimates,  being  based  on  the  principle  of 
compound  interest,  is  more  accurate.  Where  the  chief  factor  in  popu- 
lation change  is  migration,  or  where  the  relative  importance  of  natural 
increase  is  much  affected  by  migration,  the  arithmetical  method  may  be 
the  more  accurate.  The  arithmetical  method  has  been  the  one  found 
most  reliable  in  the  United  States  and  is  the  method  used  most  com- 
monly in  the  past  by  the  Bureau  of  the  Census.  The  method  best 
adapted  to  a  given  population  can  be  ascertained  by  taking  the  last  two 
intercensal  periods  and  finding  whether  the  rate  of  increase  during  the 
last  intercensal  period  was,  when  based  upon  the  increase  during  the  pre- 
ceding intercensal  period,  at  the  rate  indicated  by  the  arithmetical  or  the 
geometrical  method. 

Geometrical    Method. — As    previously    stated,    the    geometrical 
method  is  based  upon  the  principle  of  compound  interest. 

Assuming  a  decennial  census,  let 
P  =population  in  1900. 
P'=population  in  1910. 

r  =the  annual  increase  per  unit  of  population. 
Then  the  population  w^ould  be — 

In  1901=P  (l+r) 

In  1902=P  (l  +  r)2 

In  1903=P  (1-1-r-)' 

In  1910  (PO=P  (H-r)^° 

P' 


^p.=l+r  and  ^^  p-: 


In  practice  the  calculation  would  be  made  with  the  aid  of  a  table 
of  logarithms,  and  given  the  value  of  r  the  estimated  population  for 
any  intercensal  or  post  censal  date  is  readily  obtained.  For  post  censal 
dates  the  estimated  population  would  be — 

Inl911=P'  (1  +  r) 
In  1912=P' (l+r)2 
In  1913=P'  (1+r)  3 
n'^year=P'  (l+r)° 

The  registrar  general  of  England  and  Wales  uses  the  geometrical 
'^lothod  for  England  and  Wales  as  a  whole  and  a  modified  method  for 
icsser  subdivisions. 
33 


09  t  AM/l'AL  ST  A 'I' I  ST  I CS 


MARRIAGE   STATISTICS 


Marriage  statistics  are  of  interest  because  of  the  information  they 
give  regarding  the  social  life  of  the  people  and  the  estaljlishment  of 
families  and  households,  and  because  of  the  relation  of  marriages  to 
population  growth  through  their  influence  on  the  birth  rate.  Thei? 
consideration  naturally  precedes  that  of  birth  statistics. 

The  data  for  marriage  statistics  are  obtained  by  the  registration  of 
marriages.  The  common  custom  in  the  United  States  is  to  require  per- 
sons desiring  to  marry  to  obtain  first  a  license  from  a  designated  official. 
This  license  is  presented  to  whoever  performs  the  marriage  ceremony. 
The  person  officiating  is  required  to  register  the  marriage.  Those  re- 
sponsible for  the  completeness  of  marriage  records  are  therefore  in  this 
country  usually  the  clergy  and  justices  of  the  peace.  There  is  seldom 
much  difficulty  in  securing  complete  records  of  marriages,  and  the 
amount  and  value  of  the  information  given  by  marriage  statistics  depend 
upon  the  nature  and  extent  of  the  facts  recorded  relating  to  the  con- 
tracting parties. 

In  England  and  Wales  marriage  statistics  are  compiled  by  the  regis- 
trar general  of  marriages,  births,  and  deaths.  In  this  country  the  official 
responsible  for  the  compilation  of  marriage  records  varies. in  the  several 
States.  The  United  States  Bureau  of  the  Census  has  compiled  statistics 
of  marriage  and  divorce  in  the  United  States  from  1867  to  1906.  These 
were  published  in  1909. 

Marriage  Rates. — Marriage  rates  may  be  expressed  as  the  number  of 
marriages  for  each  1,000  population.  While  this  method  gives  certain 
information  of  a  definite  character  and  is  useful  for  comparing  different 
years  of  the  same  community  and  different  communities  of  similar 
population  composition,  it  is  not  useful  in  comparing  populations  in 
which  the  proportion  of  single  persons  of  marriageable  age  is  not  the 
same.  For  the  purpose  of  comparing  marriage  rates,  therefore,  the 
more  exact  method  is  to  express  the  rate  as  the  number  of  marriages  or 
persons  married  for  each  1,000  unmarried,  divorced,  and  widowed,  of 
marriageable  age,  usually  those  over  15  years  of  age. 

Factors  Influencing  Marriage  Rates. — Marriage  rates  are  usually  in- 
fluenced by  economic  conditions.  National  prosperity  increases  the 
rate,  economic  depression  reduces  it.  For  the  same  reasons  it  is  influ- 
enced by  the  demand  for  labor  and  the  rate  of  wages.  The  relation  of 
the  adopted  standard  of  living  to  the  average  wage  has  a  similar  effect. 
In  the  absence  of  other  factors,  the  marriage  rate  is  usually  a  fair  index 
of  the  relation  of  average  income  to  standard  of  living. 

The  marriage  rate  may  also  be  affected  by  the  frequency  of  divorce 
and  remarriage.     A  high  birth  rate  tends  to  increase  the  marriage  rate 


BIllTH  STATISTICS 


995 


in  succeeding  years.  In  conimimities  such  as  mining  towns  and  new 
industrial  centers  the  marriage  rate  may  be  limited  by  the  presence  of  a 
relatively  small  number  of  marriageable  women. 

The  marriage  rate  in  a  city  may  be  fictitiously  high,  due  to  the  fact 
that  many  couples  from  the  surrounding  country  and  small  towns  may 
go  there  for  the  purpose  of  being   married,   returning  then  to   their 


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1880 

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1895 

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Fig.  137. — Births  (Including  Stillbibths)  ,  Persons  Married,  and  Deaths  (Exclud- 
ing Stillbirths) — Registered  Per  1,000  Population  Per  Annum— Michigan, 
1871  TO  1912. 

homes.  In  a  country  affected  by  emigration  a  relatively  large  propor- 
tion of  the  migrants  are  apt  to  be  young  men  and  women,  the  women 
frequently  following  after  the  men  have  become  located.  This  naturally 
affects  the  marriage  rate  of  the  home  country. 

Uses  of  Marriage  Registration. — The  purpose  of  the  registration  of  a 
marriage  is  largely  to  protect  the  home  and  family.  It  furnishes  reliable 
evidence  upon  which  to  base  the  legitimacy  of  children  and  the  dower 
rights  of  women. 

BIRTH  STATISTICS 


Statistics  of  births  are  of  interest  mainly  because  of  their  relation 
to  population  growth,  the  excess  of  births  over  deaths  being  known  as 
the  "natural  increase."  Growth  of  population  has  been  the  object  of 
concern  to  nations  largely  because  of  its  effect  in  determining  the  future 
military  strength  and  the  number  of  men  available  for  purposes  of  of- 


996  VITAL  STATISTICS 

fense  and  defense.  The  practically  stationary  population  of  France  has 
for  some  time  been  the  subject  of  comment,  but  with  her  limited  terri- 
tory it  is  a  question  whether  the  people  as  a  whole  are  not  better  off  with 
the  present  population  than  they  would  be  with  a  larger  one.  More 
people  mean  greater  congestion  and  more  intense  competition.  During 
the  last  century  Great  Britain,  Germany,  Austria,  and  Eussia  have  trebled 
in  population.  Had  France  done  the  same,  she  would  now  have  nearly 
80  millions  of  people,  and  it  is  doubtful  whether  this  would  have  added 
to  the  happiness  and  welfare  of  the  race  except  in  case  of  war  with  some 
more  populous  country. 

It  is  undoubtedly  better  to  have  a  people  proportionate  in  number 
to  land  area  and  natural  resources  than  to  have  a  teeming  population 
with  the  consequent  economic  problems.  It  would  seem  more  in  keeping 
with  modern  ethics  to  strive  for  a  people  composed  of  intelligent,  physic- 
ally sound  individuals  free  from  disease  and  properly  housed,  fed,  and 
clothed,  whose  days  furnished  time  for  both  labor  and  recreation  under 
conditions  which  conduced  to  physical  and  mental  welfare  and  not  to 
deterioration,  rather  than  to  strive  for  mere  numbers. 

To  the  health  officer  and  sanitarian  birth  statistics  have  only  casual 
interest.  Birth  registration,  however,  which  furnishes  the  data  from 
which  the  statistics  are  made,  is  important  not  only  in  public  health 
work  but  in  other  ways  as  well. 

Registration  in  the  United  States. — In  legislation  the  registration  of 
births,  marriages,  and  deaths  were  formerly  usually  associated  and  pro- 
vided for  by  the  same  laws.  Since  1900,  however,  this  has  not  been 
generally  true  in  the  United  States,  where  the  practice  has  developed 
of  providing  separately  for  the  registration  of  births  and  deaths. 

A  model  bill  for  the  registration  of  births  and  deaths  recommended 
for  enactment  by  the  several  State  legislatures  has  been  drafted  and 
indorsed  by  the  American  Medical  Association  in  consultation  with  rep- 
resentatives of  the  Bureau  of  the  Census,  the  Children's  Bureau,  the 
American  Public  Health  Association,  the  American  Bar  Association, 
and  a  number  of  other  organizations  and  societies  national  in  scope.  The 
essential  features  of  this  law  have  been  adopted  by  a  number  of  States. 
It  is  important  that  other  States  should  also  enact  it,  for  it  is  without 
question  as  effective  a  law  as  any  that  has  been  proposed  for  adoption 
in  this  country.  It  is  also  highly  desirable  that  the  laws  of  the  several 
States  on  the  subject  be  uniform,  if  the  Bureau  of  the  Census  is  to 
compile  the  records  for  statistical  purposes.  The  power  to  legislate  on 
such  matters  resides  with  the  individual  States.  The  only  means  the 
Bureau  of  the  Census  has  of  preparing  national  birth  and  death  statistics 
is  to  compile  the  records  registered  in  the  several  States  under  State  laws. 
This  is  done  by  making  copies  of  the  birth  and  death  certificates  regis- 
tered in  the  various  States  and  from  these  copies  taking  the  data  for  sta- 


BIETH  STATISTICS  997 

tistical  tabulations.  The  adoption  of  a  uniform  law  would  therefore  have 
distinct  advantages,  even  if  it  were  possible  for  State  legislatures  indi- 
vidually to  draft  better  ones. 

United  States  Eegistration"  Aeea  for  Births. — A  registration 
area  for  births  has  been  designated  by  the  Bureau  of  the  Census,  begin- 
ning with  the  year  1915.  The  area  for  1915  contained  the  States  of 
Maine,  New  Hampshire,  Vermont,  Massachusetts,  Connecticut,  Ehode 
Island,  ISTew  York,  Pennsylvania,  Michigan,  and  Minnesota,  and  the  Dis- 
trict of  Columbia.  The  statistics  of  births  will  be  compiled  for  this 
area  from  transcripts  made  of  the  birth  certificates  filed  in  the  respective 
States  in  the  same  manner  that  mortality  statistics  are  comj^iled  from 
State  records. 

Source  of  Data. — While  the  data  from  which  population  statistics 
are  derived  are  obtained  by  direct  enumeration,  the  data  from  which 
birth  statistics  are  compiled  are  gotten  by  registration.  The  usual  re- 
quirement is  that  whenever  a  child  is  born  either  the  attending  phy- 
sician or  midwife,  or,  in  their  absence,  the  parents  or  the  head  of  the 
household  in  which  the  birth  occurred,  shall  register  with  an  official 
designated  for  the  purpose  certain  information  regarding  the  child 
and  its  parents. 

Nature  of  Information  Secured  by  Eegistration. — The  informa- 
tion required  to  be  registered  concerning  each  child  born  usually  in- 
cludes certain  facts  relating  to  the  child  and  the  circumstances  of  its 
birth,  together  with  certain  items  concerning  the  parents.  The  essential 
facts  are  the  name  of  the  child,  its  sex,  date  and  place  of  birth,  and 
whether  born  alive  or  stillborn,  and  the  names  and  residence  of  the  pa- 
rents. There  are  many  other  items  of  information  concerning  births 
which  are  of  the  greatest  value  and  serve  various  purposes,  such  as  the 
age,  color,  nativity,  and  occupation  of  the  parents,  whether  the  child  is 
a  single  birth,  a  twin,  or  triplet,  and  whether  legitimate  or  illegitimate. 
These  facts  are  usually  required  to  be  stated. 

The  items  registered  serve  two  principal  purposes.  They  serve,  first, 
to  identify  the  child  and  to  establish  its  age  and  parentage,  and,  second, 
to  furnish  statistical  data. 

While  in  the  enumeration  of  the  population  the  original  observer, 
upon  the  accuracy  of  whose  work  population  statistics  largely  depend, 
is  the  census  enumerator;  in  birth  registration  the  original  observer, 
upon  whom  dependence  must  be  placed,  is  usually  the  physician  attend- 
ing at  the  birth,  sometimes  the  midwife,  and  in  the  absence  of  these  the 
parents. 

Births  are  usually  required  to  be  registered  with  an  official  appointed 
for  the  purpose  and  known  as  a  registrar.  Customarily  it  is  the  same 
official  with  whom  deaths  are  registered.  At  times  a  small  fee  has  been 
paid  to  the  person  making  the  registration  or  filling  out  the  certificate. 


998  VT^WI.  STxVTISTICS 

This  custom,  however,  is  likely  to  create  in  the  minds  of  majiy  tlie  idea 
that  the  registration  is  a  matter  of  discretion — tliat  if  the  fee  is  not 
wanted  there  is  no  compulsion  to  file  the  certihcate  and  that  the  forfeit- 
ing of  the  fee  annuls  the  obligation.  This  is  especially  true  in  the  United 
States,  where  physicians  and  midwivos  have  in  many  instances  not  yet 
come  to  realize  that  the  importance  of  proper  registration  may  mean  so 
much  to  the  child  and  its  parents  that  no  accoucheur  has  completed  his 
task  nor  fulfilled  his  obligations  to  the  child  and  its  mother  until  an 
accurately  filled  out  certificate  has  been  filed  with  the  registrar.  The 
failure  to  file  such  a  certificate  is  such  a  neglect  of  the  interests  of  both 
patients,  the  child  and  the  mother,  that  it  would  seem  proj)er  to  class  it 
with  malj^ractice. 

Eirth  Rates. — There  are  several  ways  of  expressing  the  birth  rate. 
Each  method  of  statement  gives  information  not  given  by  the  others. 

Eate  Per  1,000  Population. — The  birth  rate  may  be  expressed  as 
the  number  of  births  occurring  during  a  year  for  each  1,000  of  the  popu- 
lation. This  is  known  as  the  crude  birth  rate,  and  is  based  upon  the  total 
estimated  mean  population  for  the  year — that  is,  for  the  calendar  year, 
the  population  estimated  as  of  July  1,  The  crude  birth  rate  shows  the 
net  result  to  the  community  of  the  several  factors  governing  reproduc- 
tion— the  number  of  women  of  child-bearing  age,  the  number  of  those 
who  are  married,  the  frequency  of  illegitimacy,  etc.  In  conjunction  with 
the  crude  death  rate  it  shows  the  ratio  at  which  the  community  is  repro- 
ducing itself  by  natural  increase.  It  is  a  quite  satisfactory  basis  for 
comparing  the  birth  rate  of  different  years  for  the  same  community  or 
that  of  different  communities  having  populations  of  similar  composition. 
It  is  unsatisfactory  for  the  comparison  of  populations  having  different 
proportions  of  females  of  child-bearing  age  or  of  married  women — a 
mining  town  or  new  industrial  center  may  have  comparatively  few 
women ;  a  fashionable  residential  district  may  have  a  relatively  large  fe- 
male population,  most  of  which  consists  of  unmarried  servants. 

Rate  Per  1,000  Women  op  Ciiild-Bearing  Age. — Birth  rates  may 
be  expressed  as  the  number  of  births  occurring  during  the  year  per  1,000 
women  of  child-bearing  age.  For  this  purpose  the  female  population 
between  the  ages  of  15  and  45  years  as  determined  by  census  enumera- 
tion, or  by  estimation  for  intercensal  and  post  censal  years,  is  taken. 
The  proportion  of  women  of  these  ages  in  the  population  having  been 
ascertained  by  a  census,  the  same  relative  proportion  is  assumed  to  be 
maintained  until  a  succeeding  census  shows  a  change. 

This  method  gives  rates  that  furnish  a  much  better  basis  for  the 
comparison  of  different  communities,  inasmuch  as  it  gives  the  births 
in  proportion  to  the  number  of  potential  mothers.  It  is  not,  however, 
satisfactory  under  all  conditions,  and  the  method  next  described  yields 
more  useful  information. 


BIRTH  STATISTICS 


999 


Eate  of  Legitimate  Births  Per  1,000  Married  Women"  of  Child- 
Bearing  Age  (15  to  41  or  15  to  49  Years  of  Age)  and  of  Illegiti- 
mate Births  Per  1,000  Unmarried  Women  of  Child-Beaeing  Age. — 
lu  different  communities  the  proportion  of  married  and  single  women 
may  differ  considerably  and  consequently  comparison  of  their  crude  birth 
rates  or  of  rates  based  on  the  number  of  women  of  child-bearing  age 
would  yield  comparatively  little  useful  information.  The  proportion  of 
married  women  in  industrial  communities  is  usually  considerably  larger 
than  it  is  in  residential  suburbs,  where  there  are  greater  numbers  of  fe- 
male servants.  To  make  allowance  for  these  differences  in  population 
composition  the  most  useful  method  of  stating  the  birth  rate  is  in  terms 
of  the  number  of  legitimate  births  per  1,000  married  women  of  child- 
bearing  age  (15  to  44  years  or  15  to  49  years)  and  the  number  of  illegiti- 
mate births  per  1,000  unmarried  women  of  this  age. 

Birth  rates  {exclusive  of  stillbirths)  per  1,000  population  in  certain  countries, 

1886  and  1913  i 


Country  or  State 


18S6 


Australian  Commonwealth 

Austria 

Denmark 

England  and  Wales 

Finland 

France 

German  Empire 

Hungary 

Ireland 

Italy 

The  Netherlands 

New  Zealand 

Norway 

Roumania 

Scotland 

Servia 

Spain 

Sweden 

Connecticut 

Michigan 


35.4 

28.3 

38.3 

331.3 

32.4 

25.6 

32.8 

23.9 

35.3 

'27.1 

23.9 

19.0 

37.0 

3  27.5 

45.6 

336.3 

23.2 

22.8 

37.0 

331.7 

34.6 

28.1 

33.1 

26.1 

31.2 

25.2 

42.2 

42.1 

32.9 

25.5 

42.0 

338.0 

36.7 

30.4 

29.8 

23.1 

222.2 

25.6 

221.3 

3  24.8 

1  Taken  from  the  Annual  Reports  of  the  Registrar  General  of  Births,  Deaths,  and  Marriages  in 
England  and  Wales,  1913,  and  1914,  except  the  rates  for  Connecticut,  and  Michigan,  which  were 
taken  from  the  State  reports. 

2  Includes  stillbirths. 
'  '  Year  1912. 


Sources  of  Error  in  Birth  Statistics. — The  principal  sources  of  error 
in  birth  statistics  are  to  be  found  in  defective  registration.  There  is 
no  reliable  check  by  which  the  failure  to  register  births  can  in  all  cases 
be  detected.  In  many  foreign  countries  the  people  have  become  accus- 
tomed to  register  births  and  apparently  their  returns  are  quite  complete. 
The  registration  of  illegitimate  births,  however,  is  always  less  complete 


lUUO  VITAL  STATISTICS 

than  that  of  the  legitimate.  In  the  United  States  the  people,  as  a 
Avhole,  have  in  most  sections  not  become  accaistomed  to  the  registra- 
tion of  births.  This  is  undoubtedly  due  in  part  to  a  rapidly  changing 
population  continually  receiving  large  numbers  of  immigrants  from 
various  foreign  countries — immigrants  who  are  ignorant  of  our  regis- 
tration laws  and  have  little  opportunity  of  learning  their  requirements — 
and  in  part  to  the  absence  of  effort  by  the  authorities  to  enforce  the  laws. 

As  checks  upon  the  completeness  of  birth  registration  registrars  fre- 
quently use  the  death  returns  of  young  children  and  especially  of  in- 
fants, checking  up  each  recorded  death  with  the  birth  records  to  see 
whether  the  birth  of  the  child  had  been  registered.  The  notices  of  births 
appearing  in  newspapers  are  also  often  used  for  the  same  purpose.  If 
the  christenings  were  required  to  be  notified  by  those  officiating,  this 
too  would  be  of  assistance. 

Uses  of  Birth  Registration  and  Statistics. — Birth  statistics  are  of  use 
in  ascertaining  the  natural  increase  of  the  population  (excess  of  births 
over  deaths).  They  also  give  valuable  information  regarding  the  effec- 
tive fertility  or  fecundity  of  the  race  and  of  the  frequency  of  illegit- 
imacy. These  matters  are  of  interest  to  the  economist  and  the  states- 
man. The  possession  of  birth  statistics  also  furnishes  the  basis  for  the 
present  accepted  means  of  stating  the  infant  mortality  rate,  as  will  be 
explained  later.  The  data  from  which  the  statistics  are  made,  the  regis- 
tered births,  are  on  the  other  hand  of  value  to  the  community  in  many 
ways,  and  to  the  health  officer  among  others  may  be  especially  useful. 
Some  of  the  uses  will  be  enumerated. 

Legal  Eecord. — The  registration  of  a  child's  birth  forms  a  legal 
record  that  is  frequently  useful  and  may  be  of  the  greatest  importance. 
It  establishes  the  elate  of  birth  and  the  child's  parentage  and  legitimacy. 
It  may  be  required  to  establish  the  child's  age  for  attendance  at  public 
schools,  for  permission  to  work  in  States  where  children  below  a  certain 
age  are  not  allowed  by  law  to  be  employed;  to  show  whether  a  girl  has 
reached  the  age  of  consent,  whether  individuals  have  attained  the  age 
when  they  may  marry  without  the  parent's  permission;  to  establish  age 
in  connection  with  the  granting  of  pensions,  military  and  jury  duty,  and 
voting.  It  may  be  necessary  in  connection  with  the  bequeathing  and 
inheritance  of  property  or  to  furnish  acceptable  evidence  of  genealogy, 
and  in  fact  may  be  important  and  useful  in  possible  events  too  numerous 
to  mention. 

Uses  in  Public  Health  Administration. — Eegistration  of  births 
shows  where  the  babies  are  and  makes  possible  such  observance  and  pro- 
tection as  the  health  department  desires  to  extend.  With  birth  regis- 
tration it  would  be  possible  for  the  health  authorities  to  see  that  the 
babies  are  vaccinated  against  smallpox.  This  is  one  of  the  uses  made 
of  registration  in  England.     It  would  also  be  possible  to  see  that  the 


MOEBIDITY  STATISTICS  1001 

babies  in  poor  families  have  proper  food  and  adequate  attention.  The 
observation  of  infants  under  two  weeks  of  age  would  bring  to  light  some 
eases  of  ophthalmia  which  otherwise  might  cause  serious  injury  to 
vision  and  at  times  total  blindness. 

Factors  Influencing^  Birth  Rates. — Birth  rates  are  directly  influenced 
by  the  number  of  women,  and  particularly  of  married  women,  of  child- 
bearing  age  in  the  population.  The  child-bearing  period  of  life  for 
women  may  be  considered  as  that  between  the  ages  of  15  and  49 
years;  thj  ages  between  25  and  44  years  are  for  most  races  of  the  north 
temperate  zones,  however,  those  mainly  productive. 

The  economic  and  social  status  of  the  population  may  also  affect 
the  birth  rate.  In  many  countries  at  present  the  poor  families  have 
considerably  more  children  per  family  than  have  the  well-to-do;  in  fact 
to  some  extent  the  number  of  children  per  marriage  seems  to  be  in- 
versely as  the  family  income.  On  the  other  hand,  to  a  degree  poor 
economic  conditions  are  liable  to  discourage  or  delay  marriage,  so  that 
married  couples  are  relatively  fewer  and  older  when  married,  with  fewer 
resulting  offspring.  The  adoption  of  a  more  expensive  standard  of  liv- 
ing may  produce  the  same  results  as  depressed  economic  conditions,  fewer 
and  delayed  marriages. 

The  birth  rate  is  also  affected  by  the  habits  and  customs  of  the  peo- 
ple, by  their  desire  to  have  children  or  their  desire  not  to  have  them. 
Also  a  high  infant  death  rate  is  usually  accompanied  by  a  high  birth  rate 
and,  conversely,  a  low  infant  death  rate  by  a  low  birth  rate. 


MORBIDITY  STATISTICS 

Morbidity  statistics  are  the  statistics  of  sickness  and  disease.  They 
show  the  occurrence  of  diseases  and  their  relative  prevalence  in  different 
localities  and  at  different  times.  They  differ  from  mortality  statistics 
in  that  as  relates  to  disease,  mortality  statistics  are  the  statistics  of 
fatal  cases  only,  while  morbidity  statistics  include  all  cases.  For  ex- 
ample, if  in  a  city  there  were  500  cases  of  typhoid  fever  of  which  50  ter- 
minated fatally,  mortality  statistics  would  deal  with  the  facts  relating 
to  the  50  fatal  cases,  while  morbidity  statistics  would  deal  with  the  entire 
500. 

In  the  life  of  the  individual,  after  birth  the  next  event  included  in 
vita  statistics  which  usually  occurs  is  sickness.  Disease  has  perhaps 
a  greater  influence  in  determining  the  happiness  and  efficiency  of  the 
individual  and  of  the  community  than  any  other  factor.  It  also  has 
a  direct  bearing  on  the  individual's  longevity  even  when  in  itself  not 
fatal,  for  every  attack  of  sickness  probably  does  some  injury  and  leaves 
the  human  machine  impaired  to  a  degree,  and  an  illness  occurring  a  num- 


1002 


VITAL  SIVVriSTICS 


ber  of  years  before  death  may  have  a  far  greater  infliuuice  in  determining 
the  duration  of  life  than  the  terminal  illness. 

In  speaking  of  the  usefulness  of  morbidity  registration,  Farr  has 
said: 

It  will  be  an  invaluable  contribution  to  therapeutics,  as  well  as  to 
hygiene,  for  it  will  enable  the  therapeutists  to  determine  the  duration  and 
the  fatality  of  all  forms  of  disease  under  the  several  existing  systems  of 
treatment  in  the  various  sanitary  and  social  conditions  of  the  people.  Illu- 
sion will  be  dispelled,  quackery,  as  completely  as  astrology,  suppressed,  a 
science  of  therapeutics  created,  suffering  diminished,  life  shielded  from 
many  dangers.^ 

Morbidity  statistics  have  not  evolved  apace  with  those  of  births, 
marriages  and  deaths.  This  is  due  to  the  different  purposes  they  serve. 
The  branches  which  have  to  do  directly  with  the  growth  of  population 
were  first  developed,  probably  because  of  the  need  of  the  information 


1885 

1890 

1895 

1900 

1905 

1910 

r 

7000 

~ 

/ 

\, 

/ 

s. 

6000 

/ 

V 

' 

5000 

4000 

, 

' 

_, 

3000 

1 

, 

A 

V 

/ 

zooo 

/ 

/ 

\ 

r 

/ 

_< 

1000 

J 

/ 

^_ 

__ 

^ 

^ 

■-- 

— , 

__ 

/ 

_ 

_ 

J 

_ 

Fig.   138. — Smallpox — Ntjmbbr  of  Cases  Notified  Per  Annum  in  Michigan  feom 

1883  TO  1912. 

which  they  gave  in  connection  with  taxation  and  military  enlistinent. 
Morbidity  statistics,  on  the  other  hand,  are  contemporary  with  our  com- 
paratively recently  acquired  knowledge  of  the  causes  of  diseases  and  their 
manner  of  spread.  Their  need  has  been  felt  only  with  the  advent  of 
present  day  public  health  administration,  which  in  turn  has  been  acti- 
vated in  large  measure  by  the  story  of  the  causes  of  death  told  by  mor- 
tality statistics. 

Morbidity  statistics  had  their  origin  in  the  requirement  of  the  notifi- 
cation of  cases  of  certain  dreaded  diseases,  notably  smallpox.  With  the 
appointment  of  health  officers  and  the  establishment  of  health  depart- 
ments the  notification  of  other  diseases  has  been  required.    As  knowledge 

^  Cited  by  Newsholme,  "Vital  Statistics,"  1899. 


MOETALITY  STATISTICS 


1003 


of  the  causes  of  diseases  and  their  manner  of  spread  has  been  obtained 
and  health  departments  have  been  faced  with  the  responsibility  of  con- 
trolling maladies  found  to  be  preventable,  the  list  of  notifiable  diseases 
has  grown,  for  those  responsible  for  public  health  administration  have 
found  that  it  is  impossible  to  effectively  control  a  disease  without  prompt 
information  of  when,  where,  and  under  what  conditions  cases  of  the  dis- 
ease are  occurring.  No  epidemiologist  would  think  of  attempting  to  con- 
trol an  outbreak  of  yellow  fever  or  cholera  without  inaugurating  a  de- 
pendable system  whereby  he  would  receive  prompt  and  accurate  infor- 
mation of  the  occurrence  of  cases.    It  is  just  as  impossible  to  effectively 


1885 

1890 

1895 

1900 

1905 

r9io 

400 

, 

I 

\ 

/ 

\ 

300 

\ 

\ 

, 

\ 

/ 

-4 

^ 

/ 

1 

/ 

eoo 

r 

5 

] 

~?^ 

/ 

I 

■( 

) 

<:i 

^ 

\ 

t 

i 

l^ 

X 

\ 

^ 

-v 

ff! 

\ 

100 

?11 

V11 

<0 

\ 

(0 

■S 

^ 

' 

VJ 

Ci 

2 

<o 

i^ 

y 

-<^ 

^ 

*VJ 

n 

\ 

/ 

^ 

^ 

.^ 

. 

Fig.   139. — Smallpox — Number  of  Cases  Notified  Per  Annum  for  Each  Death 
Registered — Michigan,  1883  to  1912. 


control  tuberculosis,  typhoid  fever,  scarlet  fever,  industrial  lead  poison- 
ing, or  any  other  preventable  disease  without  a  knowledge  of  the  occur- 
rence of  cases. 

The  requirements  for  notification  of  the  preventable  diseases  and 
the  extent  of  their  enforcement  may  be  taken  as  an  index  of  the  intelli- 
gence and  efficiency  of  health  administration  in  a  community. 

Morbidity  Statistics  in  the  TJnited  States. — Present  Status. — In 
the  United  States  the  authority  to  require  the  notification  of  cases  of  sick- 
ness resides  in  the  respective  State  legislatures.  In  some  of  the  States 
authority  has  been  given  to  the  State  boards  of  health  to  cover  the  sub- 
ject by  regulations.  In  most  instances  local  authorities  have  the  right 
to  supplement  the  State  requirements  by  such  additional  ones  as  may  be 
needed.  The  laws  and  regulations  of  the  several  States  differ  widely, 
as  do  also  the  efforts  made  to  enforce  them. 


1004  VITAL  STATISTICS 

The  common  and  most  general  plan  is  to  require  that  the  original 
report  be  made  by  the  physician  to  the  local  health  officer  immediately 
on  diagnosis  of  the  case.  The  local  health  officer  forwards  to  the  State 
health  department,  either  immediately  or  at  intervals,  a  transcript  or  a 
summary  of  the  notifications  received  by  him.  In  a  number  of  States 
these  reports  by  the  local  health  departments  are  made  to  the  State 
authorities  daily,  in  some  weekly,  in  one  State  twice  a  month,  in  several 
States  monthly,  and  in  a  few  States  at  longer  intervals.  In  the  States 
in  which  the  reports  are  made  daily  the  State  health  department  is  in 
a  position  to  keep  constantly  informed  regarding  the  prevalence  of  the 
notifiable  diseases.  The  same  is  in  less  measure  true  when  the  reports 
are  made  weekly.  When  the  reports  are  made  at  longer  intervals  the  cur- 
rent value  of  the  information  to  the  State  department  is  largely  lost. 

In  two  States  physicians  are  required  to  report  the  notifiable  dis- 
eases directly  to  the  State  health  department.  This,  in  effect,  makes  the 
State  health  officer  also  the  local  health  officer  and  responsible  for  the 
control  of  the  notifiable  diseases,  the  control  of  disease  and  the  notifica- 
■tion  of  cases  being  inseparable,  the  latter  giving  the  necessary  informa- 
tion by  which  to  direct  action  in  the  former. 

In  some  States  the  laws  relating  to  morbidity  reports  specify  that 
cases  of  certain  classes  of  disease  shall  be  notifiable.  These  classes  have 
been  variously  stated,  the  wording  being  in  some  instances  that  "all  cases 
of  contagious  or  infectious  diseases  dangerous  to  the  public  health  shall 
be  reported,"  in  others  "all  communicable  diseases,"  or  "all  contagious 
diseases,"  or  "all  diseases  dangerous  to  the  public  health."  When  the 
requirements  have  been  stated  in  general  terms  in  this  way  their  en- 
forcement has  been  especially  difficult  unless  the  diseases  included  have 
been  specifically  enumerated. 

The  Notifiable  Diseases. — TJie  following  named  diseases  are  those 
specified  by  the  various  State  requirements,  with  the  number  of  States 
in  which  each  is  notifiable : 

Communicable  Diseases: 

Actinomycosis 12 

Anthrax 25 

Chickenpox 31 

Cholera  (Asiatic) 45 

Dengue 11 

Diphtheria 47 

Dysentery 3 

Dysentery  (amebic) 12 

Dysentery  (bacillary) 9 

Dysentery  (epidemic) 8 

Erysipelas 10 

Favus 5 

German  measles 16 

Glanders 22 

Gonococcus  infection 10 

Hookworm  disease 15 


MOETALITY  STATISTICS  1005 

Leprosy 34 

Malaria 18 

Measles 38 

Meningitis  (epidemic  cerebrospinal) 37 

Mumps 18 

Ophthalmia  neonatorum  (conjunctivitis  of  newborn  infants) 34 

Paragonimiasis  (endemic  hemoptysis) 4 

Paratyphoid  fever 11 

Plague 36 

Pneumonia  (acute) 14 

Poliomyelitis  (acute  infectious) 36 

Puerperal  fever 8 

Rabies 20 

Relapsing  fever 5 

Rocky  Mountain  spotted  or  tick  fever 9 

Scarlet  fever 46 

Septic  sore  throat 9 

Smallpox 49 

Syphihs 11 

Tetanus 12 

Trachoma 28 

Trichinosis 11 

Tuberculosis  (all  forms) 36 

Tuberculosis  (laryngeal) 4 

Tuberculosis  (pulmonary) 8 

Typhoid  fever 42 

Typhus  fever 38 

Whooping-cough 36 

Yellow  fever 37 

Occupational  Diseases: 

Arsenic  poisoning 14 

Brass  poisoning 7 

Lead  poisoning 15 

Mercury  poisoning 14 

Phosphorus  poisoning 14 

Wood  alcohol  poisoning 7 

Caisson  disease  (compressed-air  illness) 14 

All  occupational  diseases 9 

Miscellaneous  Diseases: 

Beriberi 3 

Cancer 5 

Continued  fever  lasting  7  days 3 

Pellagra 18 

The  Model  State  Law  for  Morbidity  Reports. — Since  each  State  has 
exclusive  authority  within  its  jurisdiction  over  the  requirements  for 
the  notification  of  disease,  any  comprehensive  plan  that  may  be  devel- 
oped for  morbidity  reports  and  morbidity  statistics  must  be  the  result  of 
combined  effort  and  cooperation  and  the  enactment  by  the  several  States 
of  similar  requirements.  It  implies  also  an  adequate  enforcement  of 
these  requirements.  The  question  of  State  morbidity  reports  is  one  of 
the  most  difficult  problems  to  be  solved  by  the  State  authorities.  A 
number  of  States  have  been  endeavoring  earnestly  to  solve  the  problem 
within  their  respective  jurisdictions.     Considerable  progress  has  been 


1006 


VITAL  STATISTICS 


made  in  several  instances.  The  question  is  an  important  one,  and  is 
bound  to  receive  much  consideration  during  the  next  decade.  The  State 
health  authorities  in  conference  with  the  Public  Health  Service  had  the 


1885 

1890 

1695 

1900 

1905 

1910 

r— 

^ 

40 

35 

30 

/ 

^ 

/ 

\ 

25 

\ 

/ 

— 

/ 

s 

\ 

y 

y 

\, 

/ 

\ 

/ 

\ 

20 

/ 

s 

/ 

\ 

/ 

/ 

/ 

\ 

\ 

/ 

15 

/ 

\ 

^ 

/ 

/ 

\. 

/ 

/ 

10 

/ 

\ 

— , 

/ 

5 

_J 

_^ 

_ 

Fig.  140. 


-Scarlet  Fever — Number  of  Cases  Notified  Per  Annum  for  Each 
Registered — Michigan,  1884  to  1912. 


Death 


matter  under  consideration  for  some  time  and  in  June,  1913,  approved  a 
model  State  law  for  morbidity  reports. 

The  model  law  makes  the  occurrence  of  cases  of  the  following-named 
diseases  and  disabilities  notifiable: 


GROUP   1. — COMMUNICABLE  DISEASES 


Actinomycosis. 

Anthrax. 

Chickenpox. 

Cholera,  Asiatic  (also  cholera  nos- 
tras when  Asiatic  cholera  is  pres- 
ent or  its  importation  threatened). 

Dengue. 

Diphtheria. 

Dysentery : 
(a)  Amebic. 
(&)  Bacillary. 

Favus. 

German  measles. 

Glanders. 

Gonococcus  infection. 

Hookworm  disease. 

Leprosy. 


Malaria. 

Measles. 

Meningitis : 

(a)  Epidemic  cerebrospinal. 
{!))  Tuberculous. 

Mumps. 

Ophthalmia  neonatorum  (conjuncti- 
vitis of  newborn  infants). 

Paragonimiasis    (endemic   hemopty- 
sis). 

Paratyphoid  fever. 

Plague. 

Pneumonia  (acute). 

Poliomyelitis  (acute  infectious). 

Rabies. 

Rocky    Mountain    spotted    or    tick 
fever. 


MOEBIDITY  STATISTICS 


1007 


Scarlet  fever. 

Septic  sore  throat. 

Smallpox. 

Syphilis. 

Tetanus. 

Trachoma. 

Trichinosis. 


Tuberculosis  (all  forms,  the  organ  or 
part  affected  in  each  case  to  be 
specified). 

Typhoid  fever. 

Typhus  fever. 

Whooping-cough. 

Yellow  fever. 


GROUP   2. — OCCUPATIONAL  DISEASES   AND  INJURIES 


Arsenic  poisoning. 
Brass  poisoning. 
Carbon  monoxid  poisoning. 
Lead  poisoning. 
Mercury  poisoning. 
Natural-gas  poisoning. 
Phosphorus  poisoning. 
Wood  alcohol  poisoning. 


Naphtha  poisoning. 

Bisulphid  of  carbon  poisoning. 

Dinitrobenzine  poisoning. 

Caisson  disease  (compressed-air  ill- 
ness). 

Any  other  disease  or  disability  con- 
tracted as  a  result  of  the  nature  of 
the  person's  employment. 


GROUP   3. — MISCELLANEOUS  DISEASES 


Beriberi. 

Cancer. 

Continued  fever  lasting  seven  days. 


Drug  addictions  or  habits. 
Pellagra. 


The  Results  of  Notification  in  Certain  States  and  Cities. — The  com- 

jDleteness  of  the  reports  of  the  notifiable  diseases  in  States  and  cities  in 
which  there  is  registration  of  deaths  may  be  estimated  with  some  degree 
of  accuracy  by  comparing  the  number  of  cases  reported  with  the  number 
of  deaths  registered  as  due  to  the  same  cause.  In  doing  this,  however, 
it  must  be  borne  in  mind  that  we  do  not  know  the  fatality  rates  of  many 
diseases,  for  up  to  the  present  time  there  have  seldom  been  satisfactory 
morbidity  records  of  sufficiently  broad  application  to  permit  of  the  de- 
termination of  such  rates,  and  it  must  also  be  remembered  that  the  fatal- 
ity rates  of  many  diseases  vary  in  different  epidemics,  and  from  year  to 
year,  and  with  the  season  and  geographic  location. 

To  show  the  possibilities  of  notification  and  the  results  being  ob- 
tained in  certain  diseases  in  those  States  and  cities  in  which  notification 
has  been  developed  to  a  degree  approaching  most  closely  one  that  is 
satisfactory,  refer  to  the  table  on  page  1008. 

Source  of  Statistical  Data. — The  manner  of  collecting  the  data  from 
which  morbidity  statistics  are  compiled  is  closely  allied  to  the  registra- 
tion method  used  for  births.  The  data  consist  of  the  reports  of  cases  of 
disease  made  usually  by  physicians  and  in  some  instances  by  the  heads 
of  families  and  households.  The  original  observers  then,  upon  whom 
morbidity  statistics  depend  chiefly  for  their  completeness,  are  the  prac- 


1008 


VITAL  STATISTICS 


Diphtheria,  measles  and  typhoid  fever — Cases  reported,  deaths  registered, 
indicated  case  rates  per  1,000  population,  indicated  fatality  rates  per 
100  cases,  and  numher  of  cases  reported  for  each  fatality  registered,  in 
certain  states  and  cities,  1914- 


States  and  Cities 


Total  Cases 

Reported, 

1914 


Total  Deaths 

Registered, 

1914 


Indicated 
Case  Rate 
per  Annum 

per  1,000 
Inhabitants 


Indicated 
Fatality 

Rate 
per  100 
Cases 


Number  of 
Cases 

Notified 
for  Each 
Fatality 


Diphtheria 

Connecticut 

Michigan 

Minnesota 

New  Jersey 

New  York 

Boston,  Mass 

Cleveland,  Ohio.  .  . 
St.  Louis,  Mo._.  .  .  . 
Cincinnati,  Ohio .  . . 
Newark,  N.  J 

Measles 

Indiana 

Michigan 

New  York 

Utah._ 

Washington  (State) 

Newark,  N.  J 

Washington,  D.  C 

Denver,  Col 

Indianapolis,  Ind.  . 
Rochester,  N.  Y .  .  . 

Typhoid  fever 

Connecticut 

Maryland 

Minnesota 

New  Jersey 

Utah 

Chicago,  lU ...... . 

Detroit,  Mich 

New  York,  N.  Y. . . 
Washington,  D.  C 
Providence,  R.  I.  .  . 


2,662 
4,921 
4,577 

7,378 
22,537 

2,674 
2,392 
3,509 
1,095 
1,490 


12,074 
9,177 

47,883 
2,019 
4,281 

5,822 
947 
2,674 
5,185 
1,674 


734 
1,860 
1,784 
1,564 

668 

1,246 
537 

2,260 
340 

274 


228 
476 
347 
611 
2,006 

169 

162 

244 

71 

46 


147 
179 

832 


49 

44 
1 
5 
6 

13 


108 
197 
217 
223 
65 

170 
73 

334 
45 

26 


2.21 
1.65 
2.06 
2.62 

2.27 

3.64 
3.74 

4.77 
2.72 
3.83 


4.34 
3.08 
4.38 
4.87 
3.04 

14.96 

2.68 

10.89 

19.99 

6.93 


.61 

2.44 

.81 

.55 

1.61 

.52 

1.00 

.42 

.96 

1.12 


8.56 
9.67 

7.58 
8.28 
8.90 

6.32 
6.77 
6.95 
6.48 
3.09 


1.22 
1.84 
1.74 
.40 
1.14 

.76 
.11 
.19 
.12 

.78 


14.71 
10.59 
12.16 
14.26 
9.73 

13.64 
13.59 
14.78 
13.24 
9.49 


12 
10 
13 
12 
11 

16 
15 
14 
15 
32 


82 
51 

57 
252 

87 

132 
947 
535 
864 
129 


7 
9 
8 
7 
10 

7 
7 
7 
7 
10 


ticing  physicians.  This  is  necessarily  so,  for  neither  the  health  depart- 
ment nor  any  other  branch  of  government  can  keep  in  such  close  touch 
with  the  lives  of  the  people  as  to  be  in  a  position  to  know  of  the  occur- 
rence of  disease.  The  physician  is  the  one,  who  because  of  the  very 
nature  of  his  work  and  his  relation  to  the  community,  is  best  able  to 
have  this  information  and  furnish  it.  He  comes  in  contact  with  the  sick 
to  a  degree  others  do  not.  The  health  officer  can  not  know  of  the  pres- 
ence of  disease  except  as  it  is  reported  to  him  by  physicians.  Experi- 
ence has  shown  that  there  may  be  hundreds  of  cases  of  a  dangerous 


MOEBIDITY  STATISTICS  1009 

infection  in  a  city  and  the  health  officer  not  know  of  its  presence  in  the 
absence  of  notification. 

Unfortunately  many  practicing  physicians  have  little  knowledge  of 
the  methods  of  health  administration  and  in  common  with  people  in  gen- 
eral frequently  expect  the  health  department  in  some  mysterious  man- 
ner to  control  disease  without  placing  upon  them  the  burden  and  privi- 
lege of  cooperating  by  the  notification  of  the  occurrence  of  cases.  The 
practicing  physician,  whether  he  recognizes  it  or  not,  or  is  so  recognized 
by  the  community,  is  essentially  an  adjunct  of  the  health  department, 
for  unless  he  performs  his  part  the  health  department  is  in  large  measure 
helpless. 

Among  practicing  physicians,  at  least  in  the  United  States,  there  has 
at  times  been  the  feeling  that  the  knowledge  of  a  disease  in  a  patient  is 
privileged  information  which  they  should  not  be  called  upon  to  impart. 
In  communities  where  the  laws  require  the  notification  of  the  disease  this 
feeling  has  no  legal  basis  and  the  physician  who  does  not  make  report  is 
not  a  law-abiding  citizen.  But  aside  from  the  legal  aspects  of  the  matter 
there  would  seem  to  be  little  justification  for  such  a  course.  Every  phy- 
sician has  a  number  of  individuals  or  families  who  look  to  him,  and 
properly  so,  not  only  for  treatment,  but  also  for  such  reasonable  protec- 
tion from  disease  as  he  is  able  to  give.  The  failure  to  report  the  occur- 
rence of  a  case  of  communicable  disease  in  one  patient  may  lead  to  its 
spread  to  others  among  his  clientele  whose  rights  he  has  ignored.  He 
therefore  violates  the  intent  and  spirit  of  the  ethical  principle  of  the 
protection  of  patients  among  whom  must  be  considered  the  well  together 
with  the  sick.  The  notification  of  disease  is  in  the  interests  and  for  the 
protection  of  the  community,  and  as  his  patients  are  usually  members 
of  the  community  their  interests  are  ignored  and  because  of  the  anti- 
social whim  or  supposed  convenience  of  the  individual  affected  with  a 
notifiable  disease  they  are  deprived  of  the  protection  they  have  a  right  to 
expect.  It  would  seem  that  the  physician  who  fails  to  report  his  cases 
of  preventable  diseases  required  to  be  notified  may  properly  be  consid- 
ered as  actively  obstructing  public  health  administration. 

Eelated  in  thought  is  the  following  quotation  from  an  address  by 
Prof.  Victor  C.  Vaughan.^ 

In  the  future  the  training  of  the  medical  man  must  be  developed 
largely  with  a  view  to  his  broader  relations  to  the  public.  His  proper  func- 
tion must  be  to  prevent,  rather  than  cure  disease.  The  physician's  duties 
are  to  become  more  and  more  largely  official  in  the  sense  that  his  services 
are  to  be  rendered  to  the  community,  and  not  exclusively  to  the  individual. 

The  health  department  laboratory  may  be.  and  in  many  places  is, 
an  important  factor  in  giving  information  of  the  occurrence  of  cases 
^Pennsylvania  Medical  Journal,  November,   1913. 


1010 


VITAL  STATISTICS 


and  prevalence  of  certain  diseases.  By  having  a  diagnostic  laboratory 
with  a  trained  personnel  at  the  service  of  the  practicing  physician  the 
health  department  becomes  not  only  a  consultant  performing  gratuitous 
service  for  the  physician  but  at  the  same  time  secures  early  and  accu- 
rate information  of  many  cases  which  otherwise  might  not  be  properly 
diagnosed  and  therefore  not  reported.  A  record  of  every  positive  diag- 
nosis made  by  the  laboratory  should  be  sent  to  the  epidemiological  Ijureau 
or  other  division  of  the  health  department  responsible  for  the  control 


1890 

1895 

1900 

1905 

1910 

300 

250 

ZOO 

150 

100 

V 

V 

\ 

V 

~ 

\ 

50 

\ 

/ 

^ 

/ 

\, 

' 

s 

/ 

»v 

\ 

1 

_J 

— 

Pia. 


141. — Measles — NtrMBER  of  Cases  Notified  Per  Annum  for  Each  Death 
Registered — Michigan,  1890  to  1912. 


of  disease  and  should  for  purposes  of  morbidity  records  constitute  notifi- 
cation of  the  case  when  accompanied  by  such  necessary  information  as 
the  name,  age,  sex,  and  address  of  the  patient.  There  would  seem  to 
be  no  good  reason  why  the  services  of  the  health  department  should  not 
be  at  the  disposal  of  the  community  for  the  diagnosis  of  all  diseases. 

Nature  of  Information  Secured  by  Morbidity  Notification. — It  is  the 
practice  for  health  departments  to  furnish  to  physicians  notifica- 
tion blanks  upon  which  the  reports  are  to  be  made.  In  some  instances 
these  are  in  the  form  of  post-cards,  which  have  proper  spaces  indicated 
for  notation  of  the  required  information.  These  cards  require  the 
physician  to  affix  a  stamp  l)efore  mailing  tliem  to  the  health  department. 


MOEBIDITY  STATISTICS 


1011 


A  far  better  practice  is  that  employed  by  many  States  and  cities  of  sup- 
plying physicians  with  postal-card  forms  which  do  not  require  addi- 
tional postage  before  mailing. 

The  information  relating  to  the  reported  cases  which  physicians  are 
required  to  give  varies  in  the  several  States.  It  has  usually  been  cus- 
tomary to  require  the  physician,  in  making  his  report,  to  include  all 
the  data  regarding  the  case  desired  by  the  health  department.  In  the 
majority  of  instances  no  further  data  regarding  these  cases  are  secured 
by  the  health  officials.  While  it  may  be  impracticable  in  most  instances 
to  change  this  practice  at  the  present  time,  it  must  be  recognized  that 
a  local  health  department  should  prefer  to  collect  its  data  regarding 

1885  1890  1895  1900  1905  1910 


Fig.  142. — Diphtheria — Number  of  Cases  Notified  Per  Annum  for  Each  Death 
Registered — Michigan,  1884  to  1912. 

each  case  itself,  and  should  not  be  willing  to  depend  upon  the  physician's 
report  for  its  epidemiologic  information.  Logically,  the  only  informa- 
tion which  the  physician  should  be  depended  upon  to  give  in  his  report 
is  the  occurrence  of  a  case,  or  a  suspected  case,  of  a  given  disease  in  such 
and  such  a  person  at^  such  and  such  an  address.  He  might  properly 
be  required  to  add  to  this  such  data  as  are  matters  of  record  or  easily 
verified,  such  as  the  age,  color,  and  sex  of  the  patient,  and  similar  in- 
formation. The  local  health  department,  however,  should  be  reluctant 
to  depend  upon  the  diagnosis  of  the  practicing  physician,  unless  the  diag- 
nosis has  been  verified  by  a  trained  diagnostician  in  the  service  of  the 
department  itself.  This  has  been  the  practice  during  recent  outbreaks 
of  such  diseases  as  yellow  fever  and  plague.  It  is  also  the  practice  in 
certain  other  instances.     It  must  necessarily  become  the  practice  when- 


1012  VITAL  STATISTICS 

ever  a  determined  effort  is  to  be  made  in  the  control  of  any  preventable 
disease. 

The  Standard  Notification  Blank. — The  standard  notification  blank 
approved  by  the  State  and  Territorial  health  authorities  of  the  United 
States  in  conference  with  the  Public  Health  Service  at  their  tenth  an- 
nual conference  in  June,  1913,  calls  for  the  following  information : 

1.  Date. 

2.  Name  of  disease  or  suspected  disease. 

3.  Patient's  name,  age,  sex,  color,  and  address.     (This  is  largely  for  pur- 

poses of  identification  and  location.) 

4.  Patient's  occupation.     (This  serves  to  show  both  the  possible  origin  of 

the  disease  and  the  probability  that  others  have  been  or  may  be 
exposed.) 

5.  School  attended  by  or  place  of  employment  of  patient.     (Serves  same 

purpose  as  the  preceding.) 

6.  Number  of  persons  in  the  household,  number  of  adults  and  number  of 

children.  (To  indicate  the  nature  of  the  household  and  the  prob- 
able danger  of  the  spread  of  the  disease.) 

7.  The  physician's  opinion  of  the  probable  source  of  infection  or  origin 

of  the  disease.  (This  gives  important  information  and  frequently 
reveals  unreported  cases.  It  is  of  particular  value  in  occupational 
diseases.) 

8.  If  the  disease  is  smallpox,  the  type   (whether  the  mild  or  virulent 

strain)  and  the  number  of  times  the  patient  has  been  successfully 
vaccinated,  and  the  approximate  dates.  (This  gives  the  vaccination 
status  and  history.) 

9.  If  the  disease  is  typhoid  fever,  scarlet  fever,  diphtheria,  or  septic  sore 

throat,  whether  the  patient  had  been  or  whether  any  member  of  the 
household  is  engaged  in  the  production  or  handling  of  milk. 
(These  diseases  being  frequently  spread  through  milk,  this  informa- 
tion is  important  to  indicate  measures  to  prevent  further  spread.) 
10.     Address  and  signature  of  the  physician  making  the  report. 

These  reports  are  to  he  made  on  postal  cards  furnished  for  the 
purpose  and  mailed  immediately  to  the  local  health  department,  so 
that  proper  measures  can  he  taken  to  prevent  the  spread  of  the  disease 
or  to  find  the  focus  or  source  from  which  the  case  originated,  that  the 
occurrence  of  additional  cases  may  be  prevented.  These  reports  are  then 
to  be  forwarded  to  the  State  department  of  health,  but  before  being 
forwarded  the  local  health  department  is  to  note  thereon : 

1.  Whether  the  case  was  investigated  by  the  local  health  depaitment. 

2.  Whether  the  nature  of  the  disease  was  verified. 

3.  What  measures  were  taken  by  the  local  health  department  to  prevent 

the  spread  of  the  disease  or  the  occurrence  of  additional  cases  from 
the  same  origin. 


MOEBIDITY  STATISTICS  101  ^ 

Sources  of  Error  in  Morbidity  Statistics. — The  errors  in  morbidity 
statistics  are  due  principally  to  incomplete  notification — that  is,  to 
the  failure  of  physicians  to  report  all  cases  of  the  notifiable  diseases. 
More  cases  of  disease  usually  occur  than  are  reported.  This  can  never 
be  entirely  overcome,  for  many  diseases  vary  in  severity  under  different 
conditions,  and  some  cases  are  so  mild  that  their  true  nature  is  not 
recognized,  and  frequently  they  do  not  c(mie  to  the  attention  of  physi- 
cians. 

The  cases  notified  are  usually  correctly  diagnosed,  for  physicians 
do  not  generally  report  cases  until  they  are  practically  sure  of  the 
diagnosis,  as  the  case  remains  an  evidence  of  faulty  diagnosis  if  a 
mistake  is  made.  Then,  too,  physicians  naturally  wish  to  report  only 
those  cases  required  and  to  know  whether  a  given  case  is  one  of  these 
he  must  first  be  reasonably  sure  of  his  diagnosis. 

The  errors  in  morbidity  statistics  are  therefore  chiefly  those  of  in- 
completeness. In  this  they  resemble  birth  statistics,  although  the 
degree  of  incompleteness,  due  to  the  difference  in  the  nature  of  the  two, 
is  usually  greater  in  morbidity  statistics. 

They  differ  from  mortality  statistics,  in  which  the  principal  source 
of  error  is  incorrect  statements  of  cause  of  death.  Due  to  the  control 
possible  over  the  disposal  of  bodies  of  the  dead,  it  is  not  difficult  in 
most  communities  to  obtain  practically  complete  registration  of  deaths. 
It  is,  however,  exceedingly  difficult  to  secure  correct  statements  of  the 
causes  of  death.  The  physician  feels  compelled  to  give  a  diagnosis  in 
each  death  certificate  and  usually  does  so  even  when  he  is  uncertain  of 
the  nature  of  the  malady,  realizing  probably  that  the  body  will  be  buried 
and  that  there  will  be  nothing  to  show  the  error  if  one  is  made. 

The  tendency  is  then  in  morbidity  reports  for  the  diagnoses  to  be 
correctly  given,  but  not  all  cases  reported,  while  in  the  registration  of 
deaths  the  tendency  is  for  the  recording  of  practically  all  deaths  but 
the  filing  of  many  incorrect  statements  of  the  causes  of  death. 

Uses  of  Morbidity  Reports  and  Statistics. — In  health  administration, 
morbidity  reports — that  is,  reports  of  cases  of  sickness — serve  sev- 
eral purposes,  which  may  be  briefly  stated  to  be  as  follows : 

1.  In  the  communicable  diseases  morbidity  reports  show  the  occur- 
rence of  cases  which  constitute  foci  from  which  the  disease  may  spread 
to  others,  as  in  scarlet  fever,  typhoid  fever,  tuberculosis,  or  yellow  fever, 
and  make  it  possible  to  take  proper  precautions  to  protect  the  family  of 
the  patient,  his  associates,  or  the  community  at  large. 

2. 'In  some  diseases  morbidity  reports  make  it  possible  to  see  that 
the  sick  receive  proper  treatment,  as  in  ophthalmia  neonatorum,  diph- 
theria, and,  in  certain  cities,  tuberculosis.  The  reporting  of  cases  of 
ophthalmia  in  the  newborn  makes  it  possible  to  save  the  sight  of  some 
infants  who  would  otherwise  not  receive  adequate  treatment  until  after 


1014  VITAL  STATISTICS 

much  damage  had  been  done.  In  diphtheria  the  health  department  can 
be  of  service  in  furnishing  antitoxin.  Some  cities  furnish  hospital  or 
other  relief  to  consumptives  who  would  otherwise  be  without  proper 
treatment. 

3.  In  diseases  that  are  not  communicable,  such  as  those  due  to 
occupation  or  environment,  reported  eases  show  the  location  of  con- 
ditions which  are  causing  illness  or  injury.  This  makes  it  possible 
to  remedy  the  faulty  conditions,  so  that  others  may  not  be  similarly 
injured. 

4.  In  certain  diseases,  of  which  the  cause  or  means  of  spread  is 
unknown,  morbidity  reports  show  their  geographic  distribution  and 
varying  prevalence  and  the  conditions  under  which  cases  occur.  This 
information  has  great  potential  value  in  attempts  to  ascertain  their 
causes  and  means  of  spread. 

5.  Eeports  of  the  occurrence  of  disease  are  necessary  to  show  the 
need  of  certain  sanitary  measures  or  works  and  to  control  and  check 
the  efficiency  of  such  measures  or  works  when  put  into  operation.  In 
pulmonary  tuberculosis  such  reports  show  the  number  of  consumptives 
in  the  community  and  the  need  of  sanatoria.  In  malaria  they  show 
the  prevalence  of  the  disease,  the  need  for  drainage  and  other  anti- 
mosquito  work,,  the  efficiency  of  such  work  when  in  operation,  and  when 
a  change  in  the  prophylactic  measures  or  additional  ones  are  necessary. 
In  typhoid  fever  they  show  faults  in  the  water  supply  or  in  the  control' 
of  the  production  and  distribution  of  milk  or  in  the  disposal  of  excreta 
in  special  localities. 

6.  Morbidity  reports  when  recorded  over  a  period  of  time  and  prop- 
erly compiled  become  a  record  of  the  past  occurrence  of  disease.  They 
show  the  relative  prevalence  of  disease  from  year  to  year  and  under 
varying  conditions.  They  show  the  effect  of  the  introduction  of  public- 
health  measures  and  of  sanitary  works.  They  give  a  history  of  disease 
not  obtainable  in  their  absence. 

Morbidity  Rates. — Crude  Morbidity  Eates. — Morbidity  rates  may 
be  expressed  as  the  number  of  cases  of  a  given  disease  occurring  during  a 
year  per  1,000  of  the  total  population,  or  the  rate  may  be  expressed  as 
the  number  of  cases  per  10,000  or  per  100,000  population.  Giving  the 
rate  per  1,000  population  has  the  advantage  of  employing  the  same 
population  unit  as  that  used  for  expressing  birth,  marriage,  and  death 
rates.  It  has,  however,  what  has  been  considered  by  some  a  disadvan- 
tage, namely,  that  the  rates  will  frequently  be  expressed  by  fractions 
where  the  1,000  unit  of  population  is  taken  as  the  basis.  For  this  Yeason 
10,000  and  100,000  population  units  have  often  been  used.  The  medical 
officer  of  the  local  government  board  of  England  and  Wales  uses  the  1,000 
unit  in  stating  morbidity  rates. 

Specific  Morbidity  Eates. — Diseases  limited  entirely  or  principally 


MORBIDITY  STATISTICS  1015 

to  certain  ages  or  to  certain  classes  of  the  population  should  be  ex- 
pressed also  in  rates  of  the  number  of  cases  per  1,000  persons  in  the 
population  of  that  age  or  class.  Diseases  limited  to  childhood  should 
be  expressed  as  rates  per  1,000  children;  diseases  limited  to  women 
should  be  expressed  as  rates  per  1,000  women.  Occupational  disease 
rates  should  be  expressed  in  terms  of  the  number  of  cases  per  1,000 
persons  employed. 

Specific  morbidity  rates  showing  the  incidence  of  disease  by  age 
groups,  sex,  occupation,  and  economic  or  social  condition  will  be  possi- 
ble with  the  improved  notification  methods  which  are  being  gradually 
adopted. 

Fatality  Bates. — The  fatality  or  case  mortality  rate  of  a  disease 
is  usually  expressed  in  terms  of  the  number  of  deaths  per  100  cases; 
that  is,  as  the  percentage  of  cases  which  terminate  fatally.  In  calculat- 
ing fatality  rates  it  is  to  be  borne  in  mind  that  among  cases  reported 
during  one  week,  month,  or  year,  all  or  part  of  the  fatal  terminations 
may  occur  during  a  succeeding  week,  month,  or  year. 

Hospital  Statistics  and  Sickness  Insurance  Eecords. — In  a 
number  of  foreign  countries  much  valuable  information  regarding  sick- 
ness rates,  aside  from  that  of  the  commonly  notifiable  diseases,  is  being 
secured  from  the  workingmen's  sickness  insurance  records.  In  some 
countries  hospital  statistics  are  compiled  and  furnish  data  of  much  value. 
Bolduan^  has  suggested  a  plan  for  compiling  hospital  morbidity  statistics 
in  this  country.  The  method  is  especially  applicable  to  the  hospitals  of 
a  large  city,  but  might  be  used  for  the  hospitals  of  an  entire  State 
and  is  capable  of  being  made  nation  wide  in  scope.  The  essential  fea- 
ture of  the  plan  is  the  filling  out  of  "discharge  certificates,"  analogous 
to  ordinary  death  certificates,  on  the  discharge  of  each  patient  from  a 
hospital.  These  discharge  certificates  are  then  sent  to  a  central  filing 
bureau,  preferably  the  health  department,  and  there  classified  and 
analyzed. 

The  fund  of  valuable  information  which  might  be  acquired  by  the 
use  of  the  statistical  method  in  the  study  of  hospital  experience  and 
the  proper  treatment  of  hospital  statistics  has  been  most  ably  discussed 
by  Frederick  L.  Hoffman  in  his  work  on  "The  Statistical  Experience 
Data  of  the  Johns  Hopkins  Hospital,  Baltimore,  Md.,  1893-1911."  '' 

It  is  also  especially  desirable  to  have  statistics  of  the  insane  and 
mentally  defective.  New  Jersey  has  recently  enacted  a  law  requiring 
the  notification  of  cases  of  mental  deficiency  and  of  epilepsy. 

Factors  Influencing  Morbidity  Rates. — The  factors  which  influence 
morbidity    rates    and    the    prevalence    of    sickness    are    the  manifold 

^Bolduan,  Charles  F. :  "Hospital  Morbidity  Statistics,"  New  York  Medical 
Journal,  March,   1913,  p.  643. 

"  The  Johns  Hopkins  Hospital  Reports.    Monographs,  New  Series  No.  IV. 


1016  VITAL  STf^TISTICS 

direct  and  indirect  causes  of  disease.  Tlicre  are  certain  widely  acting 
indirect  factors  which  increase  morbidity  by  lessening  individual  resist- 
ance. There  are  other  factors  which  are  specific  for  individual  diseases. 
In  malaria  the  direct  cause  is  infectious  anopheline  mosquitoes,  and 
the  indirect  cause  swamps  and  stagnant  water  in  which  the  mosquitoes 
breed.  The  factors  influencing  typhoid  fever  rates  are  commonly  the 
milk  supply,  the  water  supply,  the  manner  of  disposal  of  excreta, 
presence  of  flies,  the  extent  to  which  houses  are  screened,  personal  and 
social  habits,  etc.  In  an  industrial  community  the  morbidity  from  occu- 
pational diseases  and  from  diseases  caused  indirectly  by  the  conditions 
attending  certain  kinds  of  labor  constitutes  a  factor  the  importance  of 
which  is  beginning  to  be  realized. 

Notification  of  Occupational  Diseases. — Most  civilized  nations  have 
'during  the  last  hundred  years  undergone  an  industrial  revolution. 
It  has  been  within  this  period  that  the  large  factory  with  its  hundreds 
or  thousands  of  workers  has  had  its  development  and  that  many  of  our 
present  industries  and  the  majority  of  our  industrial  processes  have  been 
developed.  So  great  has  been  this  change  in  the  industrial  life  of  the 
people  that  there  has  been  developed  a  new  and  important  branch  of 
hygiene  and  sanitation  which  is  properly  termed  industrial  hygiene. 
With  this  industrial  development  there  have  evolved  new  diseases  and 
disabilities  due  to  the  nature  of  the  individual's  work  or  to  the  condi- 
tions incident  to  the  work.  Not  only  have  new  diseases  in  a  sense  been 
evolved,  but  a  number  of  diseases  previously  rare  have  become  much 
more  common.  Under  existing  social  conditions  a  large  proportion  of 
the  people  are  engaged  in  some  occupation,  and  the  diseases  of  occupa- 
tion, merit  the  attention  and  consideration  of  the  community. 

Due  largely  to  the  activities  of  the  American  Association  for  Labor 
Legislation  the  question  of  the  control  of  occupational  diseases  has 
during  the  last  few  years  been  receiving  much  consideration.  Naturally 
the  first  step  in  the  control  of  the  industrial  diseases  was  the  securing 
of  a  means  by  which  the  occurrence  and  prevalence  of  these  diseases 
might  be  known  to  those  whose  duty  it  would  be  to  control  them.  For 
this  purpose,  and  largely  because  of  the  activities  of  the  American 
Association  for  Labor  Legislation,  a  number  of  States  have  since  1911 
enacted  laws  requiring  the  notification  of  certain  occupational  diseases. 

A  number  of  State  laws  require  cases  of  occupational  diseases  to  be 
notified  to  the  State  health  department,  and  others  require  the  notifi- 
cations to  be  made  to  the  State  labor  office.  The  results  of  notification 
have  not  been  as  yet  satisfactory.  This  may  be  due  to  the  newness  of  the 
idea  to  the  physician  of  considering  whether  a  disease  is  occupational  in 
origin.  The  medical  schools  have  given  little  attention  to  the  subject. 
It  is  highly  important  to  the  practicing  physician  that  he  have  a  knowl- 
edge of  the  industries  of  his  communitv  and  of  the  diseases  and  disabil 


MOETALITY- STATISTICS  1017 

ities  they  are  likely  to  cause.  The  proper  and  successful  treatment  of 
patients  necessarily  depends  upon  a  knowledge  of  the  direct  or  indirect 
cause  of  the  individual's  ailment,  and  in  an  industrial  community  this 
will  depend  frequently  upon  a  knowledge  of  occupational  diseases. 

A  number  of  States  have  enacted  laws  which  should  in  a  way  be 
much  more  successful  in  bringing  to  light  the  occurrence  of  these  dis- 
eases (Illinois,  Missouri,  Ohio,  and  Pennsylvania).  The  plan  referred 
to  is  that  of  requiring  certain  industries  to  have  their  employees  ex- 
amii>ed  physically  by  competent  physician  at  stated  intervals  to  ascer- 
tain whether  there  exist  in  the  employees  any  ailments  or  disabilities 
due  to  the  nature  of  their  occupation.  The  physicians  making  these 
examinations  naturally  become  in  time  expert,  if  they  are  not  so  in  the 
beginning,  and  the  examination  of  the  employees  in  this  way  will  guar- 
antee the  finding  of  a  large  proportion  of  the  cases  of  industrial  dis- 
eases, and  that  in  most  instances  in  their  earliest  stages.  If  the  occupa- 
tional diseases  are  to  be  controlled,  it  is  necessary  that  the  occurrence 
of  cases  be  ascertained  in  some  way,  for  the  occurrence  of  each  case  shows 
the  existence  of  conditions  which  have  produced  disease  in  one  employee 
and  will  in  all  probability  produce  it  in  others.  Each  case  notified 
shows  a  danger  spot. 

MORTALITY  STATISTICS 

Mortality  statistics  are  statistics  of  deaths.  They  are  of  interest 
primarily  because  of  their  relation  to  changes  in  population.  Aside 
from  the  factor  of  emigration,  mortality  statistics  show  the  losses  in 
numbers  being  sustained  by  the  population,  just  as  birth  records  show 
the  additions.  Where  migration  is  a  factor  having  an  appreciable 
effect  upon  population  it  likewise  merits  statistical  consideration,  for  it, 
too,  represents  population  gains  and  losses. 

Mortality  statistics  have  performed  another  important  service  in 
creating  an  interest  in  public  health  administration  and  securing  sup- 
port for  sanitary  measures.  They  show  the  extent  of  the  loss  by  death 
caused  by  diseases.  In  the  absence  of  m.orbidity  records  they  have  also 
frequently  been  used  as  an  index  of  the  prevalence  of  certain  infections. 
It  has  been  possible  to  use  mortality  statistics  for  the  latter  purpose  on 
the  assumption  that-  the  fatality  rates  of  disease  are  fairly  constant. 
However,  we  should  bear  in  mind  what  Newsholme  has  said : 

The  registration  of  deaths  gives  a  very  imperfect  view  of  the  preva- 
lence of  disease.  *  *  *  It  is  fallacious  to  assume  any  fixed  ratio  between 
sickness  and  mortality.  The  fatality  of  a  given  infectious  disease  varies 
greatly  in  different  outbreaks  under  varying  conditions.  The  highest  ratio 
of  sickness  is  occasionally  found  associated  with  a  favorable  rate  of  mor- 
tality. 


1018 


VITAL  STATISTICS 


This  absence  of  fixed  fatality  rates  is  sliown  by  the  experience  in 
the 'United  States  with  smallpox,  in  which  the  ratio  of  deaths  to  cases 
has  varied  from  1 :1.000  to  1 :3 ;  measles,  in  which  the  ratio  of  deaths 
to  cases  has  been  from  1:800  to  1:20;  typhus  fever  (Brill's  disease),  in 
which  it  has  varied  from  1:5  to  practically  no  fatality;  and  typhoid 
fever,  in  which  the  ratio  has  varied  from  1 :24  to  1 :5. 

Registration  of  Deaths  in  the  United  States. — The  history  of  the 
registration  of  deaths  in  England  and  the  United  States  is  coupled  with 
that  of  marriages  and  births.  In  the  United  States  dependable  registra- 
tion was  first  enforced  in  Massachusetts  and  New  Jersey.  Other  States 
have  had  laws  of  various  types,  mostly  inadequate.  Only  recently  have 
any  number  of  States  secured  anything  like  complete  registration.  The 
bringing  about  of  accurate  death  registration  in  the  United  States  is  due 
largely  to  the  efforts  made  by  the  Bureau  of  the  Census,  and  especially 
to  the  untiring  efforts  of  Dr.  Cressy  L.  Wilbur,  formerly  chief  statistician. 
Bureau  of  the  Census. 

United  States  Registration  Area  for  Deaths. — The  registration  area 
for  deaths  established  by  the  United  States  Bureau  of  the  Census  in- 
cludes the  States  and  cities  in  other  States  which  effectively  enforce 
satisfactory  registration  laws  and  in  the  opinion  of  the  Director  of  the 
Census  have  at  least  90  per  cent,  of  all  deaths  registered.  This  area 
was  first  established  in  1880  and  at  that  time  included  Massachusetts, 
New  Jersey,  and  certain  cities  in  other  States.  The  States  included  for 
1915  were: 


California. 

Minnesota. 

Ohio. 

Colorado. 

Missouri. 

Pennsylvania. 

Connecticut. 

Montana. 

Rhode  Island. 

Indiana. 

New  Hampshire. 

Utah. 

Kansas. 

New  Jersey. 

Vermont. 

Kentucky. 

New  York. 

Virginia. 

Maine. 

North    Carolina 

(mu- 

Washington. 

Maryland. 

nicipalities    of 

1,000 

Wisconsin. 

Massachusetts. 

population  or  over  in 

Michigan. 

1900). 

The  registration  citi 

es  in  non-registration  sta 

tes  were : 

Alabama : 

Key  West. 

Belleville. 

Birmingham. 

Pensacola. 

Chicago. 

Mobile. 

Tampa. 

Decatur. 

Montgomery. 

Georgia : 

Evanston. 

Delaware : 

Atlanta. 

Jacksonville. 

Wilmington. 

Augusta. 

Quincy. 

District  of  Columbia 

Savannah. 

Springfield. 

Florida : 

Illinois : 

Louisiana : 

Jacksonville. 

Aurora. 

New  Orleans 

MORTALrrY  STATIST[C!S 


lOlC 


Mississippi : 

Hattiesburg. 

Jackson. 

Meridian. 

Natchez. 

Vicksburg. 
Nebraska : 

Lincoln. 

Omaha. 


Oregon : 

Portland. 
South  Carolina : 

Charleston. 
Tennessee : 

Chattanooga. 

Jackson. 

Knoxville. 


Memphis. 

Nashville. 
Texas : 

El  Paso. 

Galveston. 

San  Antonio. 
West  Virginia : 

Wheeling. 


During  the  present  year  (1916)  the  states  of  North  Carolina  and 
South  Carolina  have  been  admitted  to  the  registration  area  for  deaths  by 
the  Director  of  the  Census. 

Source  of  Data. — The  original  information  from  which  mortality  sta- 
tistics are  derived  is  obtained  by  the  registration  of  deaths.  This  is 
commonly  accomplished  by  the  use  of  a  blank  or  schedule  prepared  for 
the  purpose  and  in  this  country  known  as  a  death  certificate.  The 
model  law  for  the  registration  of  births  and  deaths  provides  that  no 
body  shall  be  interred  or  otherwise  disposed  of  or  removed  or  tempora- 
rily held  pending  further  disposition  "more  than  72  hours  after  death 
unless  a  permit  for  burial,  removal,  or  other  disposition  thereof  shall 
have  been  properly  issued  by  the  local  registrar  of  the  registration  dis- 
trict in  which  the  death  occurred  or  the  body  was  found.  And  no  such 
burial  or  removal  permit  shall  be  issued  by  any  registrar  until,  wherever 
practicable,  a  complete  and  satisfactory  certificate  of  death  has  been 
filed  with  him  .  .  .''  This  insures  the  making  of  a  death  certificate 
and  its  registration  in  each  instance  of  death  unless  the  body  is  sup- 
reptitiously  and  illegally  disposed  of.  It  therefore  guarantees  prac- 
tically complete  registration.  In  the  rural  districts  of  some  localities 
bodies  are  frequently  interred  in  private  burial  grounds  and  on  farms 
in  some  chosen  spot  on  the  premises.  Under  these  conditions  bodies 
would  occasionally  be  buried  without  registration,  due  to  ignorance  of 
the  law. 

The  Standard  Death  Certificate. — The  standard  death  certificate  in 
use  throughout  the  registration  area  for  deaths  calls  for  the  following 
information : 

Place  of  death. 

Name,  sex,  color,  race,  conjugal  condition,  age,  date  of  birth,  occupa- 
tion, and  birthplace  of  decedent,  name  and  birthplace  of  father,  maiden 
name  and  birthplace  of  mother. 

Signature  and  address  of  informant  giving  preceding  information. 

Date  and  time  of  death  and  a  statement  as  to  the  duration  of  medical 
attendance  on  the  decedent,  the  cause  of  death,  and  its  duration,  are  to  be 
given  by  the  attending  physician,  if  any,  last  in  attendance. 

When  the  decedent  was  a  recent  resident  or  died  in  a  hospital  or  other 


1020  VITAL  STATISTICS 

institution,  the  length  of  residence  at  plaeo  of  death  is  to  be  given  and  also 
the  former  or  usual  residence  and  the  place  where  the  disease  or  injury  was 
contracted. 

The  daite  and  intended  place  of  burial  and  the  address  of  the  under- 
taker are  to  be  given  over  the  undertaker's  signature. 

The  date  when  the  certificate  is  filed  is  inserted  by  the  registrar  with 
his  signature. 

The  responsibility  of  seeing  that  a  certificate  is  properly  made  out 
and  filed  with  the  registrar  rests  primarily  upon  the  undertaker,  accord- 
ing to  the  provisions  of  the  model  law. 

Sources  of  Error. — In  the  use  of  mortality  statistics  as  well  as  other 
statistics  erroneous  and  unwarranted  conclusions  are  sometimes  arrived 
at  by  attempting  to  compare  incomparable  data.  Mortality  rates  se- 
cured by  lax  enforcement  or  faulty  methods  of  registration  can  not 
properly  be  compared  with  those  based  upon  complete  registration.  Nor 
can  the  rates  of  communities  with  populations  of  different  sex  and  age 
composition  be  compared  unless  proper  allowances  are  made  and  the 
rates  expressed  in  terms  of  the  same  population.  For  example,  it  is 
improper  to  compare  the  mortality  rate  of  an  aggregation  of  young 
men  picked  for  physical  soundness,  such  as  an  army  or  navy,  with 
the  crude  or  general  mortality  rate  of  a  civilian  population.  The  near- 
est means  of  making  comparison  would  be  to  compare  the  rate  of  the 
picked  body  of  men  with  the  rate  among  men  of  the  same  age  groups 
in  the  civil  population.  But  even  this  would  be  faulty,  for  the  one 
group  would  consist  of  men  specially  picked  for  physical  fitness  while 
the  other  group  would  include  the  fit  and  the  unfit,  the  strong  and 
the  weak.  Nor  is  it  possible  to  compare  the  mortality  rate  of  any  special 
population  group  with  the  rate  of  the  population  from  which  it  has  been 
derived  by  intentional  or  other  process  of  selection  unless  the  differences 
in  population  composition  are  considered.  Thus  it  would  give  little 
information  of  value  regarding  the  effect  of  locality  and  environment 
upon  the  duration  of  life  to  compare  the  mortality  rate  of  New  York 
City  or  the  registration  area  of  the  United  States  with  that  of  the 
Canal  Zone  without  taking  into  account  any  differences  which  may 
have  been  produced  in  the  age  and  sex  composition  of  the  two  popula- 
tions by  the  selective  process  naturally  operating  in  the  case  of  the 
Canal  Zone.  For  the  same  reason  there  is  little  to  be  gained  by  com- 
paring the  mortality  rate  of  any  American  city  or  State  with  that  of 
the  civil  employees  of  the  Philippine  Islands  or  any  other  similar  group 
unless  based  upon  an  analysis  of  age  and  sex  composition  of  the  pop- 
ulations. 

Another  possible  source  of  error  in  mortality  statistics  which  re- 
quires to  be  considered  is  the  original  data  contained  in  the  death 
certificates  from  which  the  statistics  are  compiled.     The  personal  and 


MOETALITY  STATISTICS  1031 

statistical  particulars  usually  furnished  by  some  member  of  the  family  are 
undoubtedly  in  most  instances  accurate  with  the  exception  of  the  state- 
ment of  occupation  of  the  decedent,  which  offers  unusual  difficulties, 
due  to  the  indefiniteness  of  many  of  the  terms  commonly  used  in  so 
far  as  showing  the  exact  kind  of  work  is  concerned.  This  is  due  in 
some  measure  to  the  fact  that  the  nomenclature  in  common  use  has 
not  progressed  apace  with  the  rapid  des^elopment  of  new  industries  and 
industrial  processes  and  methods.  Whereas  50  years  ago  the  statement 
of  occupation  would  have  been  in  most  cases  comparatively  simple  and 
easily  understood,  to-day  with  changed  industrial  conditions  the  matter 
requires  greater  precision  if  useful  statistical  information  is  to  result. 

Perhaps  the  most  common  error  entering  into  death  registration, 
and  therefore  into  mortality  statistics,  is  in  connection  with  the  state- 
ment of  cause  of  death.  Aside  from  the  fact  that  in  the  instances  in 
which  it  has  been  impossible  for  the  attending  physician  to  feel  rea- 
sonably certain  as  to  the  nature  of  the  terminal  illness  a  cause  of  death 
is  nevertheless  usually  stated  in  the  certificate,  and  also  the  fact  that 
at  times  the  physician  knowing  the  nature  of  the  illness  may,  in  the 
belief  that  he  is  shielding  the  family  from  odium  or  because  of  their 
whim,  intentionally  state  an  erroneous  cause  of  death,  there  still  remain 
the  many  unavoidable  errors  of  mistaken  diagnosis.  Just  how  great  a 
factor  this  last  may  be  it  is  difficult  to  estimate. 

However,  the  findings  of  Dr.  Eichard  C.  Cabot^  give  at  least  a 
hint  of  its  possible  importance  and  the  extent  to  which  it  may  affect 
that  part  of  mortality  statistics  relating  to  causes  of  death.  In  a  study 
of  3,000  autopsies  with  regard  to  the  relation  of  the  actual  cause  of 
death  as  found  post  mortem  to  the  clinical  diagnosis  Cabot  found  that 
the  percentage  of  correct  diagnosis  in  various  diseases  was  as  follows : 

Percentage  of 
Correct  Diagnosis 

Diabetes  mellitus 95 

Typhoid 92 

Aortic  regurgitation 84 

Cancer  of  colon 74 

Lobar  pneumonia 74 

Chronic  glomerulonephritis 74 

Cerebral  tumor 72 . 8 

Tuberculous  meningitis 72 

Gastric  cancer 72 

Mitral  stenosis 69 

Brain  hemorrhage 67 

Septic  meningitis 64 

Aortic  stenosis 61 

^  Cabot,  Richard  C. :  "Diagnostic  Pitfalls  Identified  During  a  Study  of  3,000 
Autopsies,"  Journal  Americcm  Medical  Association,  Dec.  28,   1912,  p.  2295. 


1023  VITAL  STATISTICS 

Percentage  of 
Correct  Diagnosis 

Phthisis,  active 59 

Miliary  tuberculosis 52 

Chronic  interstitial  nephritis 50 

Thoracic  aneurism 50 

Hepatic  cirrhosis 39 

Acute  endocarditis 39 

Peptic  ulcer 36 

Suppurative  nephritis 35 

Renal  tuberculosis 33 . 3 

Bronchopneumonia 33 

Vertebral  tuberculosis 23 

Chronic  myocarditis 22 

Hepatic  abscess 20 

Acute  pericarditis 20 

Acute  nephritis 16 

The  cases  studied  were  hospital  cases  under  conditions  assumed  to 
be  favorable  to  correct  diagnosis.  It  is  quite  safe  to  assume  that  in 
medical  practice  at  large  the  percentages  of  correct  diagnosis  would 
be  found  lower  than  those  found  by  Cabot. 

McLaughlin  and  Andrews^  carried  on  an  investigation  in  Manila 
into  the  nature  of  the  diseases  from  which  children  were  dying.  They 
made  post-mortem  examinations  of  children  in  which  certain  diseases 
had  been  given  as  the  cause  of  death.  The  diseases  selected  were  those 
appearing  most  frequently  in  death  certificates.  The  reason  for  the 
investigation  was  to  ascertain  whether  the  death  certificates  showed  the' 
real  causes  of  death  in  children  in  Manila  and  if  not  what  the  actual 
causes  of  death  were. 

A  summary  of  their  findings  was  as  follows: 


Causes  of  death  ascertained  by  autopsy. 

Cholera 40 

Beriberi 97 

Pneumonia 14 

EnterocoUtis 7 

Meningitis 4 

Nephritis 2 

Empyema 2 

Acute    tonsillitis,    pharyngitis, 

and  bronchitis 1 

Cerebral  hemorrhage 1 

Undetermined 8 

Total 176 

*  McLaughlin,  Allan  J.,  and  Andrews.  Vernon  L.:    "Studies  on  Infant  Mor- 
tality," I'hilippine  Journal  of  Science,  Vol.  V,  No.  2,  July,  1910,  p.   149. 


Assigned  causes  of  death. 

Meningitis 37 

Enteritis 22 

Convulsions 40 

Beriberi 50 

Bronchitis 27 

Total 176 


MORTALITY  STATISTICS 


1023 


In  the  registration  area  of  the  United  States  very  probably  the 
causes  given  in  death  certificates  of  children  correspond  more  nearly 
to  the  actual  causes  of  death  than  they  did  in  Manila.  This,  however, 
should  be  ascertained  by  careful  studies.  Mortality  statistics  can  not  be 
more  accurate  than  the  death  certificates  from  which  they  are  compiled. 

For  a  further  discussion  of  the  possible  scope  of  the  inaccuracies 
entering  into  mortality  statistics  because  of  the  faulty  or  incorrect 
statement  of  cause  of  death  on  death  certificates  the  reader  is  referred 


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Pig.  143. — Births  and  Deaths  (Excltjsive  of  Stillbirths)  Per  1,000  Population 
Per  Annum — Registered  in  Massachusetts,  1871  to  1911. 

to  the  Twelfth  Annual  Report  of  the  Bureau  of  the  Census  giving  mor- 
tality statistics  for  the  year  1911,  pages  36  to  38. 

Uses  of  Death.  Registration. — Death  registration  serves  a  number  of 
highly  important  purposes.  Its  functions  are  legal,  economic,  and  social. 
Death  registration  is  useful  in  preventing  and  detecting  crime  through 
the  restrictions  placed  upon  the  disposal  of  dead  bodies.  It  serves  as 
evidence  in  the  inheritance  of  property  and  in  the  settlement  of  life 
insurance  contracts  and  policies.  It  is  only  proper  that  the  time,  place, 
and  cause  of  death  of  each  individual  should  be  made  a  permanent 
record  for  both  sentimental  and  legal  reasons. 

Death  registration  makes  it  possible  to  show  by  mathematical  com- 
putations and  statistical  methods  the  extent  and  rate  of  change  in 
population  produced  by  deaths;  the  average  duration  of  life;  and,  to 
the  extent  that  the  certified  causes  of  death  have  been  correctly  stated. 


1024  VrrAL  STATISTICS 

the  relative  frequency  with  which  the  several  causes  produce  death. 
Death  statistics  by  comparison  with  birth  statistics  give  useful  infor- 
mation regarding  population  increase  or  decrease. 

Death  Rates. — Death  rates  may  be  expressed  as  the  ratio  of  the  total 
number  of  deaths,  taken  as  a  unit,  to  the  population.  For  example: 
1  in  60.  The  usual  method,  however,  is  to  express  these  rates  in  terms 
of  the  number  of  deaths  per  1,000  population,  or  in  some  instances  per 
10,000  or  even  100,000,  or  1,000,000. 

Crude  Deatpi  Eates. — The  rate  which  shows  the  proportion  of  all 
deaths  to  the  total  population,  and  which  is  usually  obtained  by  dividing 
the  total  number  of  deaths  by  the  total  population  in  thousands,  is 
known  as  the  crude  death  rate ;  also  as  the  general  or  central  death  rate. 
To  compute  the  crude  death  rate  the  total  number  of  deaths  during  a 
year  and  the  mean  population  for  the  year  (estimated  population  as 
of  the  middle  of  the  year,  for  the  calendar  year  as  of  July  1)  are  taken. 
To  illustrate :  In  a  city  having  a  total  of  900  deaths  during  a  calendar 
year,  and  an  estimated  population  of  60,000  as  of  July  1  of  the  year, 

60,000 

the   crude  death  rate  would  be  900   -^  =   15  and  would   be 

1,000 
expressed  as  15  per  1,000  population. 

Crude  death  rates  are  of  value  chiefly  to  show  the  numerical  loss 
of  the  population  by  death.  They  also  serve  as  a  satisfactory  basis  for 
the  comparison  of  the  death  rates  of  different  communities  having 
populations  of  similar  composition  as  to  age  and  sex.  For  populations 
of  dissimilar  composition  they  are  not  suitable  as  a  basis  of  comparison, 
for  the  death  rates  of  women  are  usually  lower  than  those  of  men  and 
the  death  rates  of  the  several  age  groups  vary  within  wide  limits,  and 
the  death  rate,  therefore,  depends  to  a  marked  degree  upon  the  relative 
numbers  of  males  and  females  and  the  proportion  of  the  population 
included  in  the  various  age  groups. 

Death  Eates  for  Short  Periods. — Death  rates  for  short  periods 
(for  a  week,  month,  or  quarter)  are  expressed  in  terms  of  annual  rates; 
that  is,  what  the  annual  rate  would  be  provided  deaths  occurred  through- 
out the  year  with  the  same  frequency  as  during  the  week  or  month  under 
consideration.  Death  rates  for  short  periods  are  likely  to  have  little 
significance,  as  quite  accidental  causes  may  affect  them  to  a  considerable 
degree.  Taken  for  a  number  of  years,  however,  they  give  useful  infor- 
mation regarding  seasonal  variations.  If  in  a  city  there  were  20  deaths 
during  a  given  week  and  the  mean  population  of  the  city  for  the  year 
was  60,000,  then  the  crude  death  rate  for  the  week  would  be 


365  /days  in  year\      /60,000\ 
7    ydaysinweek/  "  \  1,000/ 


20  X  —  I I  -^  I I  (population  of  city  in  thousands)  =  17.38. 


MOirrALiTY  STATiSl'K'S  1025 

The  mortality  for  the  week  would,  therefore,  be  at  the  rate  of  17.38 
per  1,000  population  per  annum. 

'  Specific  Death  Eates. — Special  or  specific  death  rates  are  the 
rates  of  specified  or  limited  subgroups  of  the  population.  These  sub- 
groups may  be  obtained  by  dividing  the  population  according  to  sex, 
age,  race,  social  condition,  occupation,  and  so  on.  Specific  death  rates 
may  be  stated  as  the  proportion  of  the  number  of  deaths  per  annum 
in  the  subgroup  per  1,000  of  the  mean  annual  number  of  the  population 
in  that  subgroup.  Sometimes  specific  death  rates  are  given  in  terms 
of  10,000,  100,000,  or  1,000,000  of  the  subgroup  population. 

Among  the  most  important  of  the  specific  rates  are  those  relating 
to  age  groups.  Their  significance  is  shown  by  the  following  statement 
of  rates  for  the  registration  States  of  the  United  States  for  the  year 
1911  : 

Death  Rate 

Age  Group  per  1,000 

Under  1  year 112 . 9 

1  to  4  years , 11.8 

5  to  9  years , 3.1 

10  to  14  years 2.2 

15  to  19  years .• 3.6 

20  to  24  years 5.2 

25  to  34  years 6.4 

35  to  44  years 8.9 

45  to  54  years 13.6 

55  to  64  years 26.2 

65  to  74  years 55.2 

75  years  and  over 138 . 9 

All  ages 13.9 

Specific  race  group  rates  are  also  important.  In  the  registration 
area  for  deaths  in  1911,  the  death  rate  for  the  white  population  was 
13.7  and  that  of  the  colored  23.7  per  1,000,  while  the  rate  of  the  two 
groups  taken  together  was  14.2  per  1,000. 

The  death  rate  differs  also  in  the  two  sexes.  In  the  registration 
area  for  deaths  in  1911  the  death  rate  for  males  was  14.7  and  for 
females  13  per  1,000. 

Standardized  Death  Eates. — Due  to  the  wide  variation  in  the 
death  rates  at  different  ages  it  is  impossible  to  satisfactorily  compare 
the  crude  death  rates  of  populations  differing  in  compositions  as 
regards  the  relative  number  of  individuals  in  the  several  age  groups. 
The  International  Statistical  Institute  recommended  (1895)  that  to 
facilitate  the  comparison  of  death  rates  the  population  of  Sweden  as  it 
existed  in  1890  be  used  as  a  standard  population  for  the  statement  of 
rates.  Eates  expressed"  in  terms  of  standard  population  are  known  as 
standardized  or  corrected  rates.  The  method  is  as  follows:  Take  the 
population  for  which  it  is  desired  to  state  the  standardized  death  rate 


10-2G  VITAL  SIW^I^ISTTCS 

and  ascertain  the  specific  death  rates  of  its  several  age  groups.  Now 
take  the  corresponding  age  groups  in  1,000,000  of  the  standard  popula- 
tion and  compute  the  number  of  deaths  that  would  have  occurred  in 
each  age  group  at  the  specific  death  rate  found  to  exist  in  the  popula- 
tion for  which  the  standard  death  rate  is  being  computed;  add  the 
number  of  deaths  which  it  is  thus  found  would  have  occurred  in  the 
age  groups  of  the  standard  population.  This  gives  the  standardized 
rate  per  1,000,000.  The  standardized  rate  per  1,000  is  obtained  by 
moving  the  decimal  point  three  places  to  the  left. 

The  standardized  death  rate  is  the  rate  which  would  have  occurred 
in  the  standard  population  if  the  death  rates  in  its  several  age  groups 
had  been  the  same  as  those  of  the  corresponding  age  groups  of  the 
population  under  consideration. 

The  registrar  general  of  births,  marriages,  and  deaths  of  England 
and  Wales  has  for  some  years  taken  for  a  standard  the  population  com- 
position of  England  and  Wales  as  shown  by  the  1901  census.  The  popu- 
lation of  Sweden  of  1890  was  divided  without  distinction  of  sex  into  the 
five  age  groups:  Under  13  months  of  age,  over  12  months  and  under 
20  years,  20  to  39  years  of  age  inclusive,  40  to  59  years  of  age  inclu- 
sive, and  60  years  of  age  and  over.  The  population  of  England  and 
Wales  is  classified  separately  by  sexes  in  quinquennial  age  groups  and 
furnishes  a  much  more  delicate  and  exact  standard  for  measurement. 
The  use  of  the  Swedish  population  standardizes  for  age;  the  use  of  the 
English  standardizes  for  both  age  and  sex. 

Factors  Affecting  Death  Rates. — Death  rates  are  affected  not  only  by 
the  statistical  methods  used  in  their  preparation  and  by  the  age,  sex, 
and  race  composition  of  the  population,  the  social,  marital,  and  eco- 
nomic status  of  the  people,  the  nature  and  conditions  of  employment  and 
the  adaptability  of  a  people  to  their  environment,  but  also  in  limited 
areas  by  a  number  of  other  factors,  such  as  the  location  of  hospitals 
and  institutions. 

ISToNRESiDENTS — HOSPITALS  AND  INSTITUTIONS. — Frequently  a  hos- 
pital or  other  institution  will  be  located  in  one  community  while  its 
patients  or  inmates  will  come  largely  from  other  places.  The  extent  to 
which  this  is  true  depends  upon  the  nature  or  reputation  of  the  hospital 
or  institution.  The  result  may  be  that  the  local  death  rate  will  be 
affected  to  an  appreciable  extent  by  deaths  of  nonresidents  in  such  insti- 
tutions. In  England  and  Wales  an  attempt  has  been  made  during 
the  last  four  or  five  years  to  overcome  this  difficulty  by  the  allocation 
of  all  deaths  in  so  far  as  possible  to  the  locality  of  usual  residence. 
In  compiling  deaths  for  a  registration  district  or  area  for  the  purpose 
of  showing  death  rates,  erroneous  results  will  be  obtained  if  the  deaths 
of  nonresidents  are  excluded  and  no  additions  made'  for  the  deaths  of 
residents  which  are   continually   occurring  and   being  registered   else- 


MORTALITY  STATISTICS 


1027 


where.  In  the  absence  of  a  dependable  means  of  including  the  deaths 
of  residents  occurring  in  other  districts  it  is,  unless  under  most  excep- 
tional circumstances,  unsafe  to  exclude  the  deaths  of  nonresidents. 

For  the  public  health  purposes  of  mortality  statistics  nonresident 
deaths  might  be  considered  as  those  of  persons  who  had  been  already 
affected  with  their  fatal  illnesses  at  the  time  they  had  come  to  the  local- 
ity and  who  had  not  developed  or  contracted  the  illnesses  in  the  locality. 

Migration. — Migration  affects  death  rates  by  changing  the  age, 
sex,  or  race  composition  of  the  population.  Migrants  are  likely  to  con- 
sist more  largely  of  males  than  of  females,  of  young  adults  than  of 
the  extremes  of  life.  The  effect  of  migration  depends  upon  whether 
the  balance  is  one  of  emigration  or  immigration  and  the  nature  of  the 
migrants  lost  or  gained. 

Birth  Rate. — Ignoring  the  question  of  migration,  a  population 
increases  because  of  the  excess  of  births  over  deaths,  natural  increase. 
In  a  stationary  population  the  birth  rate  equals  the  death  rate.  As  all 
born  must  eventually  die  the  birth  rate  depends  for  its  excess  over  the 
death  rate  upon  the  ever-increasing  number  of  child-producing  elements 
in  the  population  and  the  resulting  greater  numbers  in  the  younger  age 
groups.  Other  things  being  equal,  a  community  with  a  high  birth  rate 
will,  because  of  the  greater  proportion  of  the  population  in  the  younger 
age  groups,  have  a  lower  crude  death  rate  than  a  community  with  a 
low  birth  rate. 

Marital  Condition. — Mortality  in  certain  countries  seems  to  be 
more  dependent  on  marital  conditions  than  on  sex.  This  is  shown  by  the 
following  table  taken  from  a  paper  entitled  '"'Some  Researches  Con- 
cerning the  Factors  of  Mortality,"  by  Lucien  March  {Journal  of  the 
Royal  Statistical  Society,  London,  March,  1912)  : 

Showing  for  the  period  1886-1895,  the  number  of  deaths  -per  10,000  persons  according 
to  their  marital  status  in  France,  Prussia,  and  Sweden 


Males,  aged — 

Females,  aged — 

20-39 

40-59 

60  and 
Over 

20-39 

40-59 

60  and 
Over 

France : 

Married 

Single 

77 
103 
211 

71 

84 
201 

53 

83 
104 

153 
246 
293 

175 
231 
346 

114 
204 
190 

583 

794 

1,148 

582 

806 

1,091 

453 
690 

856 

80 

78 
145 

79 

59 

101 

66 
61 

98 

121 
166 
198 

128 
179 
172 

96 
120 
132 

456 
730 
930 

497 
729 

805 

364 

Widowed  or  divorced 

Prussia : 

Married 

Single 

Widowed  or  divorced 

Sweden : 

Married 

Single 

Widowed  or  divorced 

528 
698 

It  will  be  noted  in  this  and  following  table  that  there  has  been  a 
marked  fall  in  the  crude  rates  throughout  the  civilized  world.     Louis  I. 


]028 


VITAL  STATISTICS 


Death  rales  (exclusive  of  slillbirlhs)  per  1,000  populalion  in  certain  countries, 
1886  and  WIS  i 


Country  or  State 


Australian  Commonwealth . 

Austria 

Denmark 

England  and  Wales 

Finland 

France 

German  Empire 

Hungary 

Ireland 

Italy. 


The  Netherlands . 
New  Zealand .  .  .  . 

Norway 

Roumania 

Scotland 

Servia 

Spain. 


Sweden 

United  States  (registration  area  for  deaths) , 

Connecticut 

Massachusetts 

Michigan 


15.4 

10.8 

29.7 

3  20.5 

18.1 

12.5 

19.5 

13.8 

22.2 

16.1 

22.5 

16.1 

26.2 

^  15.0 

31.7 

3  23  3 

17.8 

17.1 

28.7 

M8.7 

21.8 

12.3 

10.5 

9.5 

16.2 

13.2 

26.7 

25.9 

18.9 

15.5 

29.6 

3  21.1 

29.3 

22.1 

16.6 

13.6 

219.8 

14.1 

16.2 

15.0 

18.6 

15.0 

8.9 

13.8 

1  Taken  from  the  Annual  Reports  of  the  Registrar  General  of  Births,  Deaths,  and  Marriages  in 
England  and  Wales,  1913,  and  1914,  except  the  rates  for  Connecticut,  Massachusetts,  Michigan,  and 
the  United  States.  • 

2  Year  1880. 

3  Year  1912. 

Dublin  ^  has  discussed  the  nature  of  this  reduction  in  the  death  rate  in 
the  United  States.  He  directs  attention  to  the  fact  that  the  reduction 
has  been  entirely  in  the  lower  age  groups,  and  that  the  death  rates  for 
the  ages  above  45  in  males  and  above  55  in  females  were  higher  in  1911 
than  in  1900.  The  following  table  illustrating  the  nature  of  the  changes 
is  taken  from  Dublin's  paper : 

Comparison  of  mortality  of  males  and  females,  by  age  groups; 
death  rates  per  1,000  population  (Dublin) 

[Registration  States  as  constituted  in  1900] 


Males 

Females 

Age 

1900 

1911 

Per  cent. 

Increase  or 

Decrease 

1900 

1911 

Per  cent. 

Increase  or 

Decrease 

Under  5 

54.2 

4.7 

2.9 

4.9 

7.0 

8.3 

10.8 

15.8 

28.9 

59.6 

146.1 

39.8 

3.4 

2.4 

3.7 

5.3 

6.7 

10.4 

16.1 

30.9 

61.6 

147.4 

—26.57 
—27.66 
—17.24 
—24.49 
—24.29 
—19.28 
—  3.70 
+  1.90 
+  6.92 
+  3.36 
+      .89 

45.8 

4.6 
3.1 

4.8 

6.7 

8.2 

9.8 

14.2 

25.8 

53.8 

139.5 

33.3 
3.1 
2.1 
3.3 

4.7 

6.0 

8.3 

12.9 

26.0 

55.1 

139.2 

—27.29 

5-9 

—32.61 

10-14 

—32.26 

15-19 

—31.25 

20-24 

—29 .  85 

25-34 

—26 .  83 

35-44 

—15.31 

45-54 

—  9.15 

55-64 

+  0.78 

65-74 

+  2.42 

75  and  over 

—  0.22 

All  Ages 

17.6 

15.8 

—10.23 

16.5 

14.0 

—15.15 

^Dublin,  Lotiis  I.:    "Possibilities   of  Reducing  Mortality  at  the  Higher  Age 
Groups,"  American  Journal  of  Public  Health,   Dec,    1913. 


M0I7TALTTY  STATISTICS 


1029 


Death  rates  per  1,000  persons  at  different  age  periods  in  New  York  City,  with  increase 
or  decrease  percentage  from  all  causes  for  the  years  186S  and  1907.     (Guilfoy) 


Rates 

Per  cent. 

Increase 

or 

1868 

1907 

Decrease 

Males 

Under  5  years 

130.6 

57.85 

—56 

5-9 

10.1 

4.58 

—55 

10-14 

5.04 

2.68 

—47 

15-19 

6.14 

5.24 

—15 

20-24 

13.42 

7.62 

—43 

25-29 

16.21 

9.42 

—42 

30-34 

18.01 

12.50 

—31 

35-44    

20.32 
26.36 

18.25 
31.84 

—10 

45-54 

+21 

55-64 

42.15 

103.71 

32.12 

49.87 
107.1 
21.13 

+  18 

65  and  over 

+  3 

All  ages 

—34 

Deith  rate-  per  1,000  persons  at  different  age  periods  in  New  York  City,  with  increase 

or  decrease  percentage  from  all  causes  for  the  years  1868 

and  1907.     (Guilfoy.) — Continued 


Ra 

Ics 

Per  cent. 
Increase 

1868 

1907 

or 
Decrease 

Females 

Under  5  years 

118.9 

9.08 

3.36 

5.74 

10.91 

12.84 

14.24 

15.83 

17.69 

29.37 

88.40 

26.52 

124.8 

9.60 

4.19 

5.92 

12.03 

14.42 

16.13 

18.08 

22.10 

35.59 

94.84 

29.24 

49.57 

3.74 

2.75 

4.14 

5.45 

6.82 

8.85 

12.44 

19.67 

38.43 

97.30 

16.53 

53.74 

4.16 

2.72 

4.65 

6.43 

8.11 

10.77 

15.54 

25.90 

44.06 

101.7 

18.97 

—58 

5-9 

—59 

10-14 

—18 

15-19 

—28 

20-24 

25-29 

30-34; 

35-44 

45-54 

—50 
—47 
—38 
—21 
+  11 

55-64 

+31 

65  and  over 

All  ages 

Both  sexes 

Under  5  years 

+  10 

—38 

—57 

5-9 

10-14 

15-19 

20-24 .- 

25-29 

30-34 

35-44    

—57 
—35 
—21 
—47 
_^4 

—33 

—14 

45-54 

55-64 

+  17 
+24 

65  and  over 

+  7 

All  ages 

—35 

1030 


VITAL  STATISTICS 


Similarly  instructive  is  the  preceding  taken  from  a  taljle  prepared  by 
Guilfoy  ^  showing  the  difference  in  the  mortality  rates  for  the  various 
age  groups  in  1868  and  in  1907  in  the  city  of  New  York. 


INFANT  MORTALITY 

Infant  mortality  is  the  mortality  of  infants  under  1  year  of  age. 
While  the  specific  death  rates  for  other  age  groups  are  given  as  the  ratio 
of  the  number  of  deaths  to  the  number  of  individuals  in  the  age  group 
as  ascertained  by  census  enumeration  and  estimated  for  intercensal  and 
post  censal  years,  it  is  not  practicable  to  do  this  for  the  first  year  of  life. 
There  is  extreme  difficulty  in  ascertaining  by  enumeration  the  infant 

Infant  mortality — Deaths  of  children  under  1  year  of  age  per  1,000  births  {exclusive  of 
stillbirths)  in  certain  countries,  1892  and  1911  ^ 


Country  or  State 


1911 


Australian  Commonwealth 

Austria 

Denmark 

England  and  Wales 

Finland 

France 

German  Empire 

Hungary 

Ireland 

Italy 

The  Netherlands 

New  Zealand 

Norway 

Roumania 

Scotland 

Servia 

Sweden 

Connecticut 

Massachusetts 


106 

68 

259 

207 

140 

106 

148 

130 

170 

114 

181 

mi 

192 

274 

207 

105 

94 

184 

2  142 

174 

137 

89 

56 

105 

2  67 

243 

197 

117 

2  108 

196 

2  138 

109 

2  75 

115 

lei 

119 

1  Taken  from  the  seventy-fourth  annual  report  of  the    registrar  general  of  births,  deaths,  and 
marriages  in  England  and  Wales,  1911,  except  the  rates  for  Connecticut  and  Massachusetts,  which 
were  taken  from  State  reports. 
•Year  1910. 


population.  This  is  due  largely  to  confusion  of  the  current  year  of  age 
with  the  completed  year  of  life.  Many  infants  less  than  12  months 
old  are  returned  at  the  census  as  1  year  of  age.  This  causes  an  under- 
statement of  the  infant  population  and  gives  an  illusory  basis  for  the 
estimation  of  infant  mortality  rates. 

^  Guilfoy,  Wm.  H. :  "At  What  Age  Periods  and  in  What  Measure  has  the 
Eeduction  in  the  Mortality  Eate  from  Tuberculosis  Manifested  Itself  in  the 
City  of  New  York  During  the  Past  Forty  Years?"  ISlew  York-  Med.  Jour.,  Nov. 
28,  1908. 


INFANT  MOKTALITY  1031 

The  commonly  accepted  method  of  stating  infant  mortality  is  as  the 
ratio  of  deaths  of  children  under  1  year  of  age  to  living  births,  and  is 
usually  expressed  as  the  proportion  of  deaths  during  the  calendar  year 
to  1,000  living  births  during  the  same  period.  To  illustrate:  If  in  a 
city  there  were  during  a  year  224  deaths  of  infants  under  1  year  of  age, 
and  if  during  the  same  year  there  were  3,000  births,  the  infant  mortality 
rate  would  be  112  per  1,000  births  per  annum. 

Infant  mortality  rates  might  be  based  upon  the  number  of  births 
during  the  preceding  year  or  upon  the  mean  of  the  number  of  births  of 
the  current  year  and  the  preceding  year.  However,  the  number  of  births 
of  the  current  year  has  been  accepted  as  the  basis  in  Great  Britain  and 
many  other  countries. 

Making  the  estimation  of  infant  mortality  depend  upon  birth  regis- 
tration is  at  present  unfortunate  in  a  way  for  those  interested  in  the  sub- 
ject as  it  relates  to  the  United  States,  owing  to  deficient  birth  registra- 
tion in  this  country  and  the  impossibility  therefore  of  estimating  infant 
mortality  rates,  except  for  certain  limited  areas.  However,  there  is  no 
other  practicable  basis  for  estimation.  There  are,  too,  other  difficulties 
to  be  encountered  in  the  use  of  incomplete  birth  registration.  In  the 
absence  of  change  in  other  factors  an  improving  completeness  of  birth 
registration  would  give  an  apparent  decreasing  infant  mortality  rate  and 
might  lead  to  unwarranted  deductions.  For  a  further  discussion  of 
the  subject  the  reader  is  referred  to  a  paper  entitled,  "Certain  Phases 
and  Fallacies  of  American  Infant  Mortality  Statistics,"  by  Edward  Bun- 
nell Phelps,  in  the  American  Journal  of  Public  Health,  Volume  III, 
No.  11,  November,  1913. 

LIFE  TABLES 

In  theory  life  tables  represent  the  duration  of  life  of  individuals  born 
at  the  same  time.  Given  a  group  of  individuals  born  in  any  one  year 
and  a  life  table  will  show  the  number  in  the  group  that  will  still  be  alive 
in  each  succeeding  year  as  long  as  any  remain.  It  will  also  show  the 
number  who  will  have  died  previous  to  any  given  year  and  the  number 
dying  during  each  year.  To  observe  a  group  of  individuals  from  the 
cradle  to  the  grave  is  under  most  conditions  impracticable,  and  besides 
yields  information  the  value  of  which  is  largely  lost  before  it  is  obtained, 
for  conditions  affecting  longevity  may  change  and  the  life  history  of 
one  generation  may  be  quite  different  from  that  of  the  next. 

Much  of  the  value  of  a  life  table  consists  in  showing  current  condi- 
tions as  they  affect  the  longevity  of  the  community  or  race.  For  this 
purpose  tables  are  constructed  from  the  information  furnished  by  an 
enumeration  of  the  population  (censup).  classified  by  age  and  sex  and 
the  registration  of  deaths  with  tlie  decedents  classified  also  by  age  and 


1032 


VITAL  S^rATIiSTICS 


sex.  The  population  age  and  sex  groups  give  the  number  and  propor- 
tion remaining  alive  at  each  year  of  age,  the  deaths  show  the  number 
dying  at  each  year  of  age.  For  the  purpose  of  getting  data  which  show 
general  conditions  prevailing  during  the  period,  and  of  avoiding  the 
errors  which  might  arise  by  using  the  death  records  of  a  year  during 
which  unusual  mortality  conditions  prevailed,  the  death  records  for  a 
number  of  consecutive  years  are  usually  used. 

Given  the  above  data,  the  expectancy  of  life  or  mean  after  lifetime 
at  a  given  age  is  readily  obtained.  The  following  table  is  one  pre- 
pared under  the  direction  of  Dr.  William  H.  Guilfoy,  registrar  of  rec- 
ords of  the  New  York  City  department  of  health  and  published  in 
the  monthly  bulletin  of  the  department  for  May,  1913.  It  compares 
the  expectation  of  life  based  on  the  mortality  experience  of  the  three 
years  1909,  1910,  and  1911,  with  that  found  by  the  late  John  S.  Billings 
based  upon  the  experience  of  1879,  1880,  and  1881 : 

Approximate  life  tables  for  the  city  of  New  York  based  on  mortality  returns  for  the 
triennials  1879  to  1881  and  1909  to  1911.     {Guilfoy.) 


Expectation  of  life,  1879 

Expectation  of  life,  1909 

Gain  (+)  or  loss 

(-)in 

Years  of 
Mortality 

to  1881 

to  1911 

years 

of  expectancy 

Males 

Females 

Persons 

Males 

Females 

Persons 

Males 

Females 

Persons 

Ages: 

-  5 

39.7 

42.8 

41.3 

50.1 

53.8 

51.9 

+10.4 

+11.0 

+  10.6 

5 

44.9 

47.7 

46.3 

49.4 

52.9 

51.1 

+  4.5 

+  5.2 

+  4.8 

10 

42.4 

45.3 

43.8 

45.2 

48.7 

46.9 

+  2.8 

+  3.4 

+  3.1 

15 

38.2 

41.2 

39.7 

40.8 

44.2 

42.5 

+  2.6 

+  3.0 

+  2.8 

20 

34.4 

37.3 

35.8 

36.6 

40.0 

38.3 

+  2.2 

+  2.7 

+  2.5 

25 

31.2 

34.0 

32.6 

32.7 

36.0 

34.3 

+   1.5 

+  2.0 

+   1.7 

30 

28.2 

31.0 

29.6 

28.9 

32.1 

30.5 

+  0.7 

+   1.1 

+  0.9 

35 

25.3 

28.1 

26.7 

25.4 

28.4 

26.9 

+  0.1 

+  0.3 

+  0.2 

40 

22.5 

25.2 

23.9 

22.1 

24.7 

23.4 

-  0.4 

-  0.5 

-  0.5 

45 

19.8 

22.4 

21.1 

18.9 

21.1 

20.0 

-  0.9 

-   1.1 

-   1.1 

50 

17.2 

19.4 

18.3 

15.9 

17.7 

16.8 

-  1.3 

-  1.7 

-   1.5 

55 

14.5 

16.4 

15.4 

13.2 

14.6 

13.9 

-  1.3 

-  1.8 

-   1.5 

60 

12.2 

13.8 

13.0 

10.8 

11.8 

11.3 

-   1.4 

-  2.0 

-   1.7 

65 

9.9 

11.2 

10.5 

8.8 

9.4 

9.1 

~   1.1 

-   1.8 

-   1.4 

70 

8.5 

9.3 

8.9 

6.9 

7.5 

7.2 

-   1.6 

-   1.8 

-   1.7 

75 

7.1 

7.5 

7.3 

5.3 

5.7 

5.5 

-   1.8 

-   1.8 

-   1.8 

80 

6.2 

6.5 

6.4 

4.1 

4.5 

4.3 

-  2.1 

-  2.0 

-  2.1 

+85 

5.4 

5.5 

5.5 

2.0 

2.4 

2.2 

-  3.4 

-  3.1 

-  3.3 

f  +24.8 

+28.7 

+26.6 

-15.3 

I  +  9.5 

-17.6 
+  11.1 

-16.6 

+  10.0 

The  Bureau  of  the  Census  issued  in  June,  1916,  life  tables  prepared 
under  the  supervision  of  Professor  James  W.  Glover.  The  tables  relate 
chiefly  to  mortality  conditions  in  the  area  known  as  the  original  regis- 
tration states  comprising  Maine,  New  Hampshire,  Vermont,  Massachu- 
setts, Ehode  Island,  Connecticut,  New  York,  New  Jersey,  Indiana,  Mich- 
igan, and  the  District  of  Columbia. 


LIFE  TABLES  •  1033 


REFERENCES 

Those  wishing  to  go  deeper  into  the  theory  and  practical  application 
of  the  various  branches  of  vital  statistics  will  find  the  following  volumes 
especially  helpful : 

1885.— Farr,  William:     "Vital  Statistics." 

1899.— Newsholme,  Arthur,  M.D.,  F.E.C.P. :  "The  Elements  of  Vital 
Statistics." 

1906. — Bailey,  William  B.,  Assistant  Professor  of  Political  Economy, 
Yale  University :  "Modern  Social  Conditions — A  Statistical  Study  of 
Birth,  Death,  Marriage,  Divorce,  Disease,  Suicide,  Immigration,  etc.,  with 
Special  Reference  to  the  United  States." 

1907.— Bowley,  Arthur  L.,  M.A.,  E.S.S.,  Lecturer  in  Statistics  at 
the  London  School  of  Economics  and  Political  Science:  "Elements  of 
Statistics." 

1912.— Yule,  G.  Udny :    "An  Introduction  to  the  Theory  of  Statistics." 

1915. — King,  Willford  I.,  M.A.,  Instructor  in  Statistics  in  the  Univer- 
sity of  Wisconsin:     "The  Elements  of  Statistical  Method." 

Annual  Reports  and  Supplements  of  the  Registrar-General  of  Births, 
Deaths,  and  Marriages  in  England  and  Wales. 

Annual  Reports  on  Mortality  Statistics  of  the  Registration  Area  for 
Deaths  of  the  United  States  by  the  Bureau  of  the  Census. 

1911. — Bureau  municipal  de  Statistique  d' Amsterdam  :  "Statistique 
Demographique  des  Grandes  Villes  du  Monde,  1880-1909." 

1907. — Statistique  generale  de  la  France:  "Statistique  Internationale 
du  Mouvement  de  la  Population  d'apres  les  registres  d'etat  civil-Resume 
retrospectif  depuis  I'origine  des  Statistiques  de  I'etat  civil,  jusqu'en 
1905." 


SECTION  X 
INDUSTRIAL  HYGIENE  AND  DISEASES  OF  OCCUPATION 

Indtietrial  hygiene  is  one  of  the  most  important  topics  in  preventive 
medicine;,  as  it  deals  with  tlie  health,  the  welfare,  and  the  human  rights 
of  the  vast  majority  of  the  population.  Industrial  hygiene  is  a  sub- 
ject in  which  the  medical,  economic,  and  sociologic  aspects  are  closely 
interwoven,  and  it  requires  a  broad  grasp  and  intimate  knowledge  of  the 
conditions  to  avoid  the  dangers  and  correct  the  injustices  to  which  work- 
people are  subjected.  The  questions  of  industrial  hygiene  strike  at  the 
very  root  of  our  social  system;  they  include  the  relation  of  capital  and 
labor^  and  the  relation  of  man  to  his  fellow  men.  The  man  of  means 
may,  to  a  large  extent,  select  not  only  the  place,  but  even  the  character 
of  his  employment.  He  can  choose  his  own  hours  of  work  and  can 
largely  control  his  environment  while  at  work,  so  far  as  it  affects  his 
health  and  comfort;  he  can  purchase  fresh  air,  sunshine,  good  food, 
rest,  recreation,  and  other  conditions  that  make  for  health,  longevity, 
and  happiness.  The  employee  must  largely  accept  the  conditions  as  he 
finds  them  and  is  frequently  denied  many  advantages,  even  necessities. 
As  the  power  of  the  employee  is  limited,  he  needs  the  assistance  of  the 
state  to  correct  the  unreasonable  demands  which  capital  has  ever  exacted 
of  labor.  Legislators  should  champion  the  rights  of  work-people,  espe- 
cially in  the  realm  of  industrial  hygiene.  Our  country  has  been  negligent 
in  this  regard  and  has  fallen  far  behind  England  and  continental  coun- 
tries. The  situation  has  received  some  assistance  through  organized 
labor,  which  has  exerted  a  good  influence  in  limiting  the  avarice  of  the 
employer,  in  shortening  the  hours  of  work,  in  obtaining  a  more  just 
share  of  the  profits,  in  improving  sanitary  conditions,  and  in  exacting 
a  modicum  of  human  consideration.  Thus  wlien  the  stone  masons  came 
to  build  the  Hygienic  Laboratory  in  Washington  they  refused  to  work 
until  a  proper  shelter  and  other  reasonable  conveniences  were  provided, 
as  required  by  their  labor  union. 

Modern  conditions  have  brought  entirely  new  problems  into  indus- 
trial hygiene.  These  have  come  about  largely  through  the  development 
of  new  industries  and  the  invention  of  new  processes,  through  improved 
and  changed  methods  of  transportation,  and  through  specialization  and 
crowding  in  cities  and  work  places,  through  artificial  light,  through 
changing  relations  between  capital  and  labor,  and  the  intensive  and  un- 
relenting pressure  of  the  times.     Some  of  the  conditions  which  oppress 

1035 


103G         HYGIENE  AND  DISEASES  OF  OCCUPATION 

the  workmen  are  brought  about  by  the  greed  of  capital  auf]  disregard 
of  the  human  machine,  but  indifference,  carelessness,  and  ignorance  of 
the  workman  himself  are  responsible  for  many  avoidable  accidents  and 
preventable  maladies.  In  Eastman's  study  of  work  accidents  in  Pitts- 
burgh it  appeared  that,  out  of  410  fatal  accidents,  the  victim  or  his 
fellow  workers  w^ere  responsible  in  188  eases  and  the  employer  in  147 
cases.  Despite  the  improvements  in  labor-saving  devices  the  human 
machine  will  ever  remain  the  most  vital  and  indispensable  machine  in 
the 'production  of  wealth — at  the  same  time  it  is  the  most  delicate  and 
sensitive  machine.  Both  from  the  standpoint  of  humanity  and  the  stand- 
point of  economy  the  human  machine  deserves  greater  care  and  consid- 
eration than  any  other  mechanism  engaged  in  the  production  of  wealth. 

There  are  especial  dangers  to  health  incident  to  certain  industries, 
such  as  liability  to  lead  poisoning  in  the  manufacture  of  white  lead;  of 
phossy  jaw  in  the  manufacture  of  matches  made  with  white  phosphorus ; 
of  caisson  disease  in  divers  and  those  who  work  in  compressed  air ;  there 
are  extra  hazards  to  life  and  limb  in  railroading,  mining,  and  among 
those  who  work  with  explosives;  there  is  a  particular  danger  to  those 
who  are  compelled  to  work  in  a  dusty  atmosphere,  more  so  if  the  dust 
is  of  an  irritating  or  poisonous  nature ;  and  there  is  danger  to  those  who 
are  compelled  to  breathe  poisonous  fumes  such  as  carbon  monoxid,  hydro- 
gen sulphid  or  mercury.  Further,  there  are  many  forms  of  neuroses  due 
to  certain  kinds  of  work;  and  finally  infections  such  as  anthrax,  glanders, 
and  hookworm  disease.  These  special  instances  represent  the  true  dis- 
eases of  occupation.  There  are  many  other  influences,  not  specifically 
inherent  to  industry,  to  which  the  workman  is  often  subjected  which 
seriously  influence  health,  such  as  poor  ventilation,  lack  of  cleanliness, 
overcrowding,  excessive  hours,  improper  light,  fatigue,  and  a  hundred 
and  one  conditions  which  affect  the  health  and  the  efficiency  of  the  work- 
man. These  examples  are  usually  considered  under  industrial  hygiene. 
Work  should  be  ennobling,  and  anything  which  tends  to  degrade  it  is 
morally  wrong. 

The  statistics  of  morbidity  and  mortality  in  relation  to  diseases  of 
occupation  need  careful  scrutiny,  especially  when  used  for  comparison. 
The  factors  which  enter  into  such  statistics  are  so  numerous  and  the  con- 
ditions so  variable  that  misleading  conclusions  are  common.  The  work- 
men come  and  go,  they  vary  very  much  in  physical  vigor  to  start  with, 
are  of  all  ages,  both  sexes,  many  nationalities,  and  are  greatly  influenced 
by  home  conditions  and  by  the  character  of  their  recreation.  Many 
industries,  while  not  in  themselves  particularly  hazardous,  are  rendered 
so  through  intemperance  or  dissipation.  1'he  statistician  must  be 
careful  to  take  all  factors  into  account  that  bear  upon  the  subject.  Some 
industries  are  blamed  for  conditions  affecting  health  that  really  are  due 
to  the  insanitary  home  conditions  and  bad  habits  of  the  individual. 


HYOTExYE  AND  DISEASES  OF  OCCUPATION 


1037 


In  recording  the  nature  of  a  man's  work  it  is  not  sufficient  simply  to 
state  that  he  is  a  laborer,  mechanic,  machinist,  mill  operator,  and  the 
like.  Such  information  is  frequently  of  no  more  value  to  the  student 
of  the  diseases  of  occupation  than  the  name  of  the  person  himself.  If 
the  person  is  a  blacksmith  or  works  with  heavy  metals  it  is  plain  that 
he  works  under  a  severe  physical  strain.  If  he  is  a  sailor  upon  a  sailing 
ship  we  know  that  he  is  exposed  to  rough  weather  and  unusually  severe 


Pig.  144. — Red  Oxid  of  Lead  and  Litharge  Being  Mixed  in  the  Mantjpactubb  op 
Storage  Batteries.  The  workman  is  wearing  a  respirator,  but  should  also  protect 
himself  with  long-wristed  gloves. 


conditions,  whereas  if  he  is  a  sailor  upon  a  modern  passenger  steamship 
the  conditions  of  his  work  may  be  no  more  severe  than  those  of  the  janitors 
and  charmen  in  a  large  office  building.  If  he  is  in  finance  we  may  be 
sure  that  he  is  subject  to  severe  nervous  strain.  It  is  therefore  not  suffi- 
cient simply  to  give  the  name  of  the  trade,  but  detailed  inquiry  should 
be  made  into  the  nature  of  the  work  and  the  particular  conditions  under 
which  he  works. 

With  the  exception  of  phosphorus,  lead,  and  mercury  poisoning,  little, 
if  any,  investigations  of  value  have  been  made  in  this  country  into  the 
vast  question  of  industrial  poisoning.     That  careful  study  carried  out 


1038         HYGIENE  Am^  mSEAHV.H  OF  OCCTJPATTON 

by  competent  authorities  is  urgently  ])e('<lc<l  can  be  seen  from  tbc;  follow- 
ing list  of  i)oisons  that  are  in  every-day  use  in  our  industries:  methyl 
alcohol,  ammonia,  anilin,  antimony,  arsenic,  arseniuretted  hydrogen  gas, 
benzol,  carbon  bisnlphid,  carbon  monoxid,  chlorid  of  lime,  chlorin,  chro- 
mium, di-nitro-benzol,  formaldehyd,  mineral  acids,  manganese,  nitro- 
benzin,  nitrous  oxids,  picric  acid,  prussic  acid,  pyridin,  sulphuretted 
hydrogen,  and  many  more. 

Our  country  has  long  nursed  the  delusion  that  the  conditions  under 
which  our  workmen  operate  are  better  than  corresponding  conditions 
abroad.  Eecent  investigations  have  shown  the  contrary  to  be  the  fact. 
Thus,  Dr.  Alice  Hamilton  discovered  25  cases  of  lead  poisoning  during 
one  year  in  a  "model"  Illinois  factory  employing  200  hands,  while  large 
English  white  lead  works  under  careful  supervision  frequently  show  not 
a  case  of  lead  poisoning  for  several  successive  years.  We  are  just  wak- 
ing up  to  the  seriousness  of  the  situation — the  first  American  Con- 
gress on  Industrial  Diseases  met  in  June,  1910.^ 

Andrews  estimates  that  in  the  United  States  30,000  wage  earners 
are  killed  by  industrial  accidents  every  year,  and  that  at  least  500,000 
more  are  seriously  injured.  A  memorial  on  industrial  injuries  prepared 
by  a  committee  of  inspectors,  appointed  by  the  President  of  the  Asso- 
ciation for  Labor  Legislation,  states  that  there  are  probably  not  less  than 
13,000,000  cases  of  sickness  each  year  among  those  engaged  in  industrial 
employments.  The  money  lost  each  year  (for  those  who  find  dollars 
more  expensive  than  lives)  is  conservatively  calculated  at  nearly  three- 
fourths  of  a  billion  dollars.  At  least  one-fourth  of  this  painful  incapacity 
for  work  and  consequent  economic  loss  can  be  prevented. 

Good  industrial  conditions  means  money  in  the  pockets  of  the  em- 
ployer: Thus,  Elliot  Washburn  reports  the  instance  of  twenty-eight 
emory  grinders  in  Massachusetts  working  in  a  badly  lighted  and  poorly 
ventilated  basement,  who  increased  their  efficiency  30  per  cent,  on  being 
transferred  to  a  well  lighted  and  ventilated  workroom. 

The  diseases  of  occupation  refer  only  to  those  diseases  which  are 
contracted  because  of  the  occupation  and  which  would  not  have  been 

*The  Massachusetts  legislature  of  1904  took  the  first  step  in  this  country 
to  obtain  definite  scientific  data  on  the  subject  of  the  occupational  diseases. 
The  State  Board  of  Health  of  Massachusetts  made  an  investigation  into  the 
sanitary  condition  of  factories,  workshops,  and  mercantile  establishments,  and 
published  its  first  report  on  the  subject  in  1907.  Since  then  several  States 
have  taken  up  the  subject,  also  the  U.  S.  Dept.  of  Labor  and  the  Amer.  Assn. 
for  Labor  Legislation.  The  Hospital  for  Industrial  Diseases  at  Milan,  opened 
March,  1910,  is  the  only  institution  in  the  world,  devoted  specifically  to  the 
investigation  and  care  of  such  diseases. 

The  earliest  successful  attempts  in  England  to  enforce  sanitation  and  to 
secure  healthy  conditions  of  work  were  introduced  by  the  Act  of  1833  involving 
the  appointment  of  paid  factory  inspectors,  who  antedated  medical  officers  of 
health   and  sanitary   inspectors. 


FUNDAMENTAL  CONSIDEEATIONS  IN  PKEVENTION   1039 

contracted  if  the  individual  had  not  engaged  in  that  particular  occupa- 
tion. Most  of  the  diseases  of  occupation  are  due  to  poisonous  and  irri- 
tating gases,  vapors,  or  dust  to  which  work-people  are  exposed.  Special 
affections  are  sometimes  caused  by  exposure  to  high  temperatures,  ab- 
normal atmospheric  pressures,  and  other  unusual  conditions  peculiar  to 
some  occupations.  These  are  the  true  occupational  diseases.  In  addi- 
tion to  these  there  are  a  large  number  of  affections  caused  by  insanitary 
factory  or  office  surroundings,  such  as  overcrowding,  bad  air,  imperfect 
light,  lack  of  cleanliness,  improper  washing  or  toilet  facilities,  etc.  When 
disease  is  contracted  or  health  undermined  through  such  insanitary  con- 
ditions it  cannot  be  regarded  as  an  inherent  or  special  danger  of  a 
particular  occupation.  If  a  person  contracts  typhoid  fever  or  diphtheria 
through  the  use  of  a  common  drinking  cup  or  a  roller  towel  in  a  fac- 
tory, workshop,  or  office  these  evidently  cannot  be  considered  occupa- 
tional diseases.  On  the  other  hand,  if  a  person  contracts  lead  poisoning 
because  he  is  required  to  handle  lead  bars  this  is  evidently  a  danger  in- 
herent to  his  occupation,  and  thus  becomes  a  true  disease  of  occupation. 
The  general  sanitary  and  hygienic  conditions  under  which  work  is  done 
are  comprised  under  the  term  "industrial  hygiene,"  while  the  maladies 
caused  by  exposure  to  poisonous  fumes,  dust,  or  other  special  dangers 
during  a  manufacturing  process  comprise  the  true  diseases  of  occupation. 
Industrial  hygiene,  from  the  standpoint  of  the  sanitarian,  is  simply  a 
special  application  of  our  general  knowledge  bearing  upon  the  health 
and  welfare  of  mankind.  Industrial  diseases,  on  the"  other  hand,  require 
a  special  study  as  to  their  causes,  symptoms,  and  modes  of  prevention. 

The  reporting  of  occupational  diseases  is  a  public  health  measure,  and 
of  first  importance  for  their  control. 

An  industry  may  be  a  nuisance  or  disturbance  to  the  community  as 
well  as  to  those  engaged  in  its  various  processes.  Thus  the  noise  of  a 
tack  factory  or  boiler  shop,  the  smells  from  glue  or  fertilizing  factories, 
or  the  fumes  from  smelting  or  chemical  works,  or  the  smoke  from  chim- 
neys or  locomotives,  wastes  from  tanneries,  paper  mills,  and  mines  do  not 
come  directly  in  the  chapter  of  industrial  hygiene,  however  closely  re- 
lated. 


SOME  FUNDAMENTAL  CONSIDERATIONS  IN  PREVENTION 

In  order  to  improve  the  hygienic  conditions  under  which  people 
work,  and  in  order  to  prevent  the  diseases  of  occupation,  five  funda- 
mental conditions  are  essential :  (1)  investigations;  (2)  laws;  (3)  fac- 
tory inspection;  (4)  penalties;  (5)  education.  It  is  self-evident  that 
before  anything  can  be  accomplished  a  careful  study  must  be  made  of 
the  facts.     These  investigations  must  include  not  only  scientific  studies, 


1040     •     HYGIENE  AND  DISEASES  OF  OCCUPATION 

but  also  economic  and  sociological  factors.  Every  large  industrial  center 
should  have  a  clinic  for  the  study  and  care  of  industrial  diseases.  The 
subject  should  be  included  in  the  curriculum  of  medical  schools.  Suit- 
able laws  are  necessary,  for  it  has  been  found  in  practice  that  the  condi- 
tions cannot  be  corrected  by  an  appeal  to  voluntary  reform.  To  be  effec- 
tive the  laws  must  provide  ample  ways  and  means  for  their  energetic  en- 
forcement. A  systematic  factory  inspection  is  necessary  in  order  not  only 
to  protect  work  people  against  the  preventable  diseases  of  occupation  and 
to  correct  sanitary  defects,  but  also  to  enforce  the  laws  concerning  hours 
of  occupation,  child  labor  laws,  and  related  subjects.  These  laws  have 
little  force  unless  they  provide  a  penalty  both  against  the  employer  and 
the  employees.  Either  party  to  the  contract  should  be  held  legally  re- 
sponsible in  case  of  violation.  Finally,  education  directed  to  the  em- 
ployer, the  employee,  and  also  to  the  public  at  large  is  necessary  to  obtain 
the  laws  and  maintain  the  standards. 

Hours  of  Work. — J^o  general  rule  can  be  laid  down  for  the  hours  of 
work,  which  may  vary  Avith  the  character  of  the  employment.  Thus 
the  hours  of  active  work  are  limited  by  a  smith  or  glass-blower,  a  worker 
in  a  caisson  or  mine,  a  locomotive  engineer,  and  other  occupations  necessi- 
tating great  muscular  effort  or  intensive  concentration,  or  exposure  to 
unnatural  conditions.  Formerly  men  worked  at  the  quieter  occupa- 
tions all  the  time  not  given  to  sleep;  noAV  the  day  is  better  divided  into 
eight  hours  of  work,  eight  hours  of  "re-creation,"  and  eight  hours  of 
sleep.  Hygienically,  it  is  important  to  have  one  full  day's  rest  each  week. 
It  cannot  be  maintained  from  the  medical  side  that  working  longer  than 
eight  hours  a  day  is  harmful  to  health,  but  it  is  held  that  no  employer 
has  the  right  to  utilize  the  greater  part  of  a  man's  day  and  thus  deprive 
him  of  the  leisure  to  which  he,  as  a  human  being,  is  entitled.  Since  his 
whole  nature  has  to  be  developed,  time  must  be  given  for  the  intellectual, 
moral,  and  physical  welfare  of  man,  which  cannot  take  place  if  the 
hours  of  employment  are  too  long,  the  work  too  hard,  or  of  a  grinding 
nature.  The  hours  of  work  depend  somewhat  upon  the  physical  exertion 
required  and  also  upon  the  nervous  tension.  The  Saturday  half  holi- 
days, especially  during  the  heated  term;  a  vacation  period,  and  a  tend- 
ency to  increase  the  number  of  holidays  are  all  signs  of  social  improve- 
ment which  make  for  health  and  happiness. 

Fatigue. — Economic  engineers  find  that  it  pays  to  give  employees  a 
rest  at  stated  intervals  and  to  guard  the  conditions  surrounding  workers, 
so  that  they  are  neither  molested  nor  interrupted,  that  the  light  and 
other  factors  are  agreeable,  and  the  sanitary  surroundings  good.  Work 
and  rest  must  be  judiciously  alternated.  Efficiency  ceases  when  fatigue 
begins.  The  danger  to  the  workman  himself,  as  well  as  to  others,  is  now 
recognized  from  a  tired  brain,  tired  nerves,  and  tired  muscles.  Acci- 
dents are  especially  prone  to  happen  to  workmen  who  are  tired.     Thus 


FUNDAMENTAL  CONSIDERATIONS  IN  PREVENTION  1041 

most  accidents  in  factories  happen  as  tlie  day  wears  on.  The  effect  of 
fatigue  on  the  occurrence  of  accidents  is  graphic-ally  shown  by  French 
and  Belgian  statistics.  The  number  of  accidents  increases  progressively 
during  the  morning  hours,  drops  after  the  noon  intermission,  and  then 
rises  from  hour  to  hour  until  the  end  of  the  working  day,  affording 
a  practical  illustration  of  Helmholtz's  experiments  in  attention  fatigue. 


Fig.  145. — An  Effective  Dust-removing  System  in  the  Boot-and-Shoe  Industry. 
Edge  trimming.     (Mass.  State  Board  of  Health.) 


Fatigue  is  not  only  dangerous  to  the  workman  himself,  hut  sometimes 
to  others;  thus  the  overwrought  and  tired-out  train  dispatcher  may 
send  trains  into  collision.  Further,  fatigue  of  certain  nerves  and 
muscles  may  result  in  definite  symptoms  such  as  writers'  cramp,  or 
more  general  manifestations  such  as  nervous  prostration.  Type- 
writers, telegraph  operators,  and  others  suffer  from  these  occupational 
neuroses. 

Next  to  fatigue,  nervous  tension  and  worry  are  very  wearing,  and 
when  combined  become  especially  harmful.  Diabetes  prevails  among 
engine  drivers  to  a  considerable  extent.  Worry,  hurry,  and  a  high 
nervous  tension  are  recognized  as  a  frequently  predisposing  cause  of  ill 


1042         HYGIENE  AND  DISEASES  OF  OCCUPATION 

health  or  breakdown  in  all  walks  of  life,  including  the  so-called  higher 
professions. 

Minors. — The  first  factory  act  in  this  country  was  passed  by  the  state 
of  New  York  in  1886.  By  this  act  no  child  under  13  years  of  age  was 
allowed  to  work  in  factories.  Since  then  the  minimum  has  been  raised 
to  14.  In  Massachusetts  it  is  now  18  years  and  under  certain  circum- 
stances 21  years.  The  injustice  to  the  child  and  the  consequence  upon 
its  health  and  development  of  subjecting  it  to  the  monotony  and  grind 
of  factory  life  are  too  evident  to  need  emphasis.  Eecently  it  has  been 
claimed  that  in  certain  districts,  as,  for  example,  the  mill  district  of  our 
southland,  the  children  are  better  off  in  a  good  textile  mill  of  modern 
construction  than  they  are  living  under  the  insanitary  conditions  of 
their  homes.  It  would  be  just  as  logical  to  state  that  they  would  improve 
in  health  if  removed  to  a  prison  or  almshouse.  The  child  of  to-day  is  the 
citizen  of  to-morrow  and  his  health  and  development  are  the  most  im- 
portant assets  of  the  state.  In  Germany  children  under  13  are  not  al- 
lowed to  work  in  factories;  between  12  and  14  they  are  not  allowed  more 
than  6  hours  per  day,  and  between  14  and  16  not  more  than  10  hours 
per  day.  Further,  they  are  not  allowed  to  begin  work  earlier  than  5.30 
a.  m.  nor  work  later  than  8.30  p.  m.,  and  one  hour  is  required  for  dinner. 
Children  are  not  allowed  at  all  in  certain  dangerous  trades,  as  coal 
mines,  etc.  In  this  country  child  labor  is  legally  prohibited  in  factories, 
upon  the  stage,  and  other  undesirable  places  in  many  of  the  states :  the 
question  with  us  is  somewhat  complicated  on  account  of  the  industrial 
competition  between  the  states.  The  regulation  of  child  labor  and  com- 
pulsory education  are  too  important  for  longer  delay.  There  are  cer- 
tain occupations  in  which  minors  under  no  circumstances  should  be  per- 
mitted to  engage.  This  includes  the  dangerous  trades  in  which  there  is 
liability  to  accident  and  the  trades  in  which  there  is  danger  to  health  on 
account  of  irritating  dust  or  poisonous  fumes.  There  are  also  certain 
occupations,  such  as  messenger  boys  or  work  about  bar  rooms,  theatres 
or  night  work,  which  should  be  entirely  prohibited  by  law  on  account  of 
the  exposure  to  temptation. 

In  Massachusetts  minors  under  eighteen  years  of  age  are  excluded 
from  the  following  occupations : 

1.  Processes  involving  exposure  to  poisonous  dusts  or  substances, 
such  as  the  manufacture  of  lead,  lead  pipe,  plumbers'  supplies;  electro- 
typing,  handling  white  lead  or  lead  monoxid  (litharge)  in  rubber  fac- 
tories; lead-paint  grinding;  lead  working  in  the  manufacture  of  storage 
batteries;  file  cutting  by  hand;  typesetting;  cleaning  or  handling  of  type 
in  printing  offices ;  glazing  in  pottery  establishments. 

2.  Processes  involving  exposure  to  irritating  dusts,  as  graphite  in 
the  manufacture  of  stove  polish;  bronzing  in  the  lithographing  business; 
cutlery  grinding  and   other  grinding;   polisliing  on   emery  or  buffing 


FUNDAMENTAL  CONSIDEEATIONS  IN  PEEYENTION  1043 

wheels ;  cutting,  grinding  and  preparing  pearl  shell ;  talc  dusting  in  rub- 
ber works;  sorting,  cutting  or  grinding  rags;  filing  grooves  in  steel 
rolls  by  hand. 

3.  Processes  involving  exposure  to  poisonous  gases  and  fumes,  as 
exposure  to  naphtha  in  the  manufacture  of  rubber  goods,  in  japanned 
or  patent  leather;  exposure  to  fumes  or  gases  from  lead  processes;  and 
the  spraying  of  amyl  acetate  on  pictures. 

4.  Processes  involving  exposure  to  irritating  gases  and  fumes,  such 
as  gassing  in  textile  factories;  singeing  in  print  works;  bleaching  and 
dyeing  works,  and  dipping  metal  in  acid  solutions. 

5.  Processes  involving  exposure  to  extremes  of  heat  and  other  condi- 
tions which  promote  susceptibility  to  disease,  as  melting  or  annealing 
glass. 

Women. — Women  are  physiologically  not  capable  of  doing  the  same 
work  as  men,  especially  during  the  period  of  maternity.  Further,  several 
days  each  month  women  are  more  or  less  incapacitated  for  most  kinds  of 
work  on  account  of  menstruation.  Pregnant  women  should  not  work 
for  several  weeks  before  labor,  and  after  labor  not  until  the  uterus  has 
undergone  involution,  which  is  a  matter  of  another  month.  In  Massa- 
chusetts the  law  requires  not  less  than  2  weeks  before  and  not  less  than 
4  weeks  after  the  birth  of  the,  child.  In  Switzerland  the  law  requires 
a  total  of  8  weeks  before  and  after  labor.  These  are  wise  laws  which 
all  enlightened  countries  should  accept.  Justice  demands  that  women 
should  be  given  full  pay  during  this  time,  which  is  of  such  great  moment 
to  her  own  health  and  that  of  her  offspring.  Mr.  Brandeis  successfully 
defended  the  constitutionality  of  the  ten-hour  law  for  women  in  Oregon. 
The  brief  submitted  by  this  eminent  jurist  in  a  similar  action  before 
the  Illinois  Supreme  Court  ^  should  be  read  by  those  interested  in  this 
subject.  The  primary  object  of  this  brief  is  to  show  that  the  demands 
of  public  health  require  legal  restrictions  in  the  work  of  women  because 
of  the  peculiar  importance  to  the  community  of  the  health  of  mothers. 
The  effect  of  overwork  on  the  different  organs  is  reviewed,  also  the  effect 
of  night  work,  of  prolonged  standing  on  the  feet,  of  foot-power  machin- 
ery, and  of  the  speeding  up  required  by  the  "piece-work  system."  The 
general  literature  upon  fatigue  and  overwork  is  reviewed. 

The  effect  of  overwork  upon  fecundity  and  upon  infant  mortality  is 
impressive.  Broggi  states  that  of  172,365  Italian  women  between  the 
ages  of  fifteen  and  fifty-four  years  who  were  employed  in  industrial  oc- 
cupations the  average  child-bearing  coefficient  was  only  about  one-third 
of  the  general  fertility  of  Italian  women. 

It  is  now  a  well-established  fact  that  infant  mortality  is  shockingly 

*  Brandeis,  Louis  D.,  assisted  by  Goldmark,  Josephine :  Brief  and  Argument 
for  Appellants.  In  the  Supreme  Court  of  the  State  of  Illinois,  December  term, 
1909. 


1044         HYGIENE  AXD  I)ISEAS1':S  OF  OCCUPATION  • 

high  among  the  baljJes  of  women  wlio  woi'k  in  factories  and  mills.  It 
has  been  shown  in  Germany  and  Eiigland  that  infant  mortality  increases 
progressively  according  to  the  increase  in  the  proportion  of  women 
obliged  to  work  outside  of  their  homes,  ajid  this  is  true  eveii  if  the 
mother's  work  results  in  higher  standards  of  comfort  in  the  home.  The 
two  classical  demonstrations  of  this  rule  are  the  great  Lancashire  cotton 
famine  and  the  Siege  of  Paris,  during  both  of  which  crises  there  were 
loss  of  employment  and  great  privation.  In  spite  of  the  starvation  and 
the  increased  general  death-rate,  the  infants'  death  rate  fell  in  Paris 
actually  to  40  per  cent,  simply  because  the  women,  being  out  of  work, 
were  obliged  themselves  to  nurse  and  care  for  their  children.  The  infant 
mortality  in  industrial  centers  such  as  Fall  Eiver,  Lowell,  and  Lawrence, 
in  Massachusetts,  which  are  mill  towns,  is  twice  as  high  as  similar  towns 
Avithout  many  factories  and  no  overcrowding. 

It  is  plainly  the  duty  of  the  nation  to  restrict  the  hours  of  work  of 
women  and  also  prohibit  their  employment  in  certain  industries  known 
to  be  particularly  hazardous  to  the  sex.  Saleswomen  should  be  provided 
with  seats  in  shops  so  as  to  avoid  the  ill  effects  of  prolonged  standing, 
they  should  have  one  or  two  days  each  month  for  rest  during  the  men- 
strual period,  and  should  be  protected  against  undue  strain  and  fatigue. 
While  women's  work  may  be  regulated  in  the  industries  and  the  hours 
of  employment  may  be  limited  by  law,  there  can  be  no  law  to  regulate 
women's  work  in  the  household  which  is  "never  done."  Men  have  still 
to  learn  the  lesson  that  nervous  breakdown  and  the  results  of  fatigue  are 
as  harmful  in  women  who  overwork  in  the  home  as  in  those  who  work 
in  shops  and. factories.  The  long  hours  and  confining  work  of  house  ser- 
vants sometimes  lead  to  anemia  and  other  troubles.  Cooks  are  exposed 
to  the  effects  of  excessive  heat  and  to  sudden  changes  of  temperature. 
Domestic  "servants"  as  a  class  supply  a  large  contingent  of  patients  in 
hospitals  and  out-clinics.  The  long  hours  and  insufficient  sleeping  ac- 
commodations, as  well  as  the  nature  of  the  work,  lead  to  ill  health  which 
may  in  part  account  for  the  disinclination  of  women  to  accept  tliis  kind 
of  service. 

Factory  Inspection. — There  is  no  longer  doubt  but  that  factory  in- 
spection is  necessary  as  a  protection  to  the  workman.  An  efficient  sys- 
tem requires  a  good  comprehensive  basic  law  and  a  capable  corps  of  in- 
spectors. The  inspectors  should  be  thoroughly  familiar  with  the  law  and 
with  the  processes  of  manufacture  and  also  with  the  problems  of  pre- 
ventive medicine.  Factory  inspectors  should  be  capable  of  making 
recommendations  outside  of  the  strict  regulations  under  which  they  op- 
erate so  as  to  improve  conditions  and  meet  the  needs  of  an  ever-changing 
situation.  Factory  inspection  really  falls  into  two  categories,  one  of 
which  deals  mainly  with  the  medical  side  and  the  other  with  the  legal 
and  economic  side.     Both  inspectors  should  take  into  account  the  social 


FUNDAMENTAL  CONSIDERATIONS  IN  PREVENTION  1045 

and  humanitarian  side.  Some  of  the  factors  which  should  engage  the 
attention  of  a  factory  inspector  are:  ventilation,  dust,  gases,  vapors, 
odors,  temperature,  moisture,  light,  cleanliness,  over-crowding,  excessive 
heat,  dampness,  drinking-water,  children,  women,  washing  facilities,  wa- 
terclosets,  cloakrooms,  receptacles  for  expectoration,  defective  sanitary 
arrangements,  hours  of  work  and  rest,  the  age  of  the  employees,  their 
physical  condition,  etc.  Hanson  points  out  that  medical  men,  through 
their  training  and  attitude,  make  the  best  factory  inspectors,  for  they 
alone  are  in  a  position  to  make  the  best  use  of  facts,  and  learn  something 


Fig.  146. — System  of  Hoods  and  Ventilators  to  Cabry  off  the  Fumes  from  the 
Furnaces  in  a  Foundry.     (Mass.  State  Board  of  Health.) 

of  the  sanitary  conditions  of  premises  where  men  and  women  work,  to 
study  the  possible  injurious  effects  of  certain  processes,  to  inspect  devices 
designed  to  protect  the  employees  against  injury  or  against  dangerous 
fumes  and  dust,  and  tt)  judge  the  effects  on  the  health  of  operatives  of 
such  substances,  as  well  as  to  detect  the  symptoms  of  certain  poisons  inci- 
dent to  such  occupations,  to  detect  and  protect  the  employees  and  others 
from  infectious  diseases,  to  make  physical  examinations  of  minors,  and 
to  collect  and  make  proper  use  of  all  facts  and  data,  including  morbidity 
and  mortality  statistics,  pertaining  to  occupational  hygiene.  The  medi- 
cal inspector  is  also  able  to  correlate  the  injurious  influences  in  the 
factorv.  in  the  home,  and  in  the  habits  of  the  individual. 


1046         HYGIENE  AND  DISEASES  OF  OCCUPATION 

Preventable  Accidents,. — The  most  obvious  and  striking  of  the  pre- 
ventable accidents  occur  on  railroads,  in  mines,  and  in  factories.  About 
10,000  persons  are  killed  and  100,000  more  or  less  seriously  injured  on 
the  railroads  of  the  iTnited  States  every  year.  Some  3,000  fatal  acci- 
dents occur  annually  in  the  course  of  mining  operations,  and  probably 
5,000  deaths  result  from  accidents,  in  the  operation  of  machinery  in 
factory  and  workshop.  Much  of  this  is  preventable,  in  fact,  prevented 
in  other  countries.  Winslow  points  out  that  fatalities  are  four  times  as 
common  among  our  railroad  employees  as  among  those  of  England,  and 
other  accidents  seven  times  as  frequent.  Coal  mining  was  nearly  as 
fatal  in  Belgium  between  1830  and  1840  as  it  is  in  the  United  States  to- 
day, but  the  Belgians  have  cut  their  death  rate  down  to  less  than  one- 
third  of  what  it  was. 

Some  special  injuries  incident  to  work  are :  spinal  curvature  from 
faulty  posture ;  fiat  feet  or  varicose  veins  from  prolonged  standing,  as  in 
nurses  and  footmen;  injuries  to  the  eyes  from  metal  splinters  or  stone 
fragments;  impairment  of  vision  from  improper  lighting,  or  eye  strain, 
as  in  garment  workers  and  gun  pointers,  or  miners'  nystagmus;  injuries 
to  the  ears,  as  rupture  of  the  tympanum  from  air  pressure  in  caissons; 
labyrinthine  disease  leading  to  deafness  in  boiler-makers  and  gunners. 
Injuries  to  the  skin  are  commonly  caused  by  violence,  but  may  result 
from  excessive  moisture,  as  hydrocystoma  of  laundresses;  chilblains  of 
cold  storage  workers;  and  ulcers  caused  by  X-ray  or  radium — most  of 
which  are  readily  preventable. 

A  system  of  workmen's  compensation,  by  which  the  victim  of  indus- 
trial accidents,  except  when  caused  by  his  own  neglect,  is  entitled  by 
right,  and  without  legal  proceedings,  to  a  proper  money  equivalent  for 
the  injury  received,  is  simple  justice  which  has  been  long  delayed  in  this 
country.  Workmen's  compensation  laws  have  been  in  successful  opera- 
tion in  all  the  principal  European  countries.  Many  of  our  larger  cor- 
porations voluntarily  and  automatically  compensate  employees  in  case 
of  accidents.  In  1910  New  York,  Montana,  and  Maryland  passed  laws 
making  such  an  arrangement  optional  or  compulsory  for  certain  classes 
of  occupations.  In  New  York  the  law  was  declared  unconstitutional. 
In  1911,  10  different  states,  California,  Illinois,  Kansas,  Massachusetts, 
Nevada,  New  Hampshire,  New  Jersey,  Ohio,  Washington,  and  Wiscon- 
sin, enacted  laws  bearing  on  this  subject. 

A  compensation  law  should  cover  all  industries  and  not  alone  those 
that  are  hazardous ;  it  should  include  disability  from  occupational  poisons 
as  well  as  from  accidents ;  the  payment  should  be  adequate  and  certain.  A 
good  compensation  laAv  is  one  of  the  best  preventive  measures,  for  it  has 
been  found  that  employers  soon  discover  it  pays  to  safeguard  the  work- 
men. 

In  the  case  of  Vennen  vs.  New  Dells  Lumber  Company,  154  N.  W. 


INDUSTRIAL  POISONS 


Massachusetts  GeneraJ  Hospital 


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„y„  pp..™ 

CEpSoWS 

DISEASES  OF  OCCUPATIOI^  1047 

Eep.  640  (Oct.  26,  1915),  the  Supreme  Court  of  Wisconsin  decided  that 
the  death  of  an  employee  caused  by  typhoid  fever,  which  was  contracted 
by  drinking  impure  water  furnished  by  the  employer,  was  the  result  of 
an  "accident"  under  the  terms  of  the  Workmen's  Compensation  Law, 
and  that  the  employer  was  liable. 

Sedentary  Occupations. — Sedentary  occupations  in  themselves  may 
lead  to  harm,  especially  in  the  cases  of  those  who  bend  forward  while  at 
work,  causing  contraction  of  the  chest  and  pressure  upon  vital  organs 
which  interferes  with  important  physiological  functions.  The  circula- 
tion is  impeded,  respirations  are  shallow,  the  utilization  of  food  is 
diminished  and  the  appetite  fails,  constipation  and  hemorrhoids  are  com- 
mon, and  there  is  a  predisposition  to  common  colds  and  diseases  of  the 
lungs. 

DISEASES  OF  OCCUPATION 

Classification  of  the  Occupational  Diseases. — Oliver  divides  the  occu- 
pational diseases  into  five  general  classes : 

(1)  Diseases  due  to  gases,  vapors,  and  high  temperatures. 

(2)  Diseases  due  to  conditions  of  atmospheric  pressure. 

(3)  Diseases  due  to  metallic  poisons,  dusts,  and  fumes. 

(4)  Diseases  due  to  organic  or  inorganic  dust  and  heated  atmos- 
pheres. 

(5)  Diseases  due  to  fatigue. 

The  principal  health  risks  in  industry,  as  far  as  we  now  know  them, 
may  be  conveniently  classified  according  to  their  nature  as  follows : 

1.  Dusts,  fumes,  gases,  vapors,  and  acids  (poisonous  and  non- 
poisonous). 

2.  Harmful  bacteria  and  microorganisms. 

3.  Compressed  or  rarefied  atmospheres. 

4.  Improper  lighting. 

5.  Extremes  of  temperature. 

6.  Excessive  strain. 

Many  other  classifications  have  been  attempted^  but  it  is  evident  that 
no  general  system  can  be  entirely  satisfactory.  Each  occupation  requires 
individual  study  and  separate  consideration.  In  many  occupations  a 
combination  of  varying  factors,  such  as  dust  fumes,  poisons,  fatigue,  etc., 
operate  coincidently.  In  the  following  pages  only  the  well-known  and 
better  studied  diseases  of  occupation  and  the  conditions  which  render 
them  hazardous,  as  well  as  methods  of  prevention,  are  considered.  The 
number  of  occupational  diseases  is  rapidly  growing  as  the  subject  is 
receiving  more  careful  attention.  Thus  recently  it  has  been  shown  that 
workers  with  heated  tallow  and  other  animal  grease  are  subject  to  gastro- 
intestinal disturbances,  apparently  due  to  the  volatile  fatty  acids  that 


10-18  IIVlilKNK  AND  DISExVSES  OF  OCCrTPATJON 

are  given  off  and  that  the  workers  ingest  and  inhale.  .Strumpf  and 
Zable  ^  describe  chronic  antimony  poisoning  among  type-setters.  Skin 
diseases  are  frequently  found  among  workers  in  the  following:  galvan- 
izing, cutters  of  glass  and  pearl  shell,  workers  with  tar,  paraffin,  arsenic, 
cement,  dyes,  printer's  ink,  chromium,  potassium  permanganate,  and 
among  polishers.  Naphtha,  carbon  bisulphid,  anilin  oil,  the  alcohols, 
and  many  other  volatile  substances  produce  occupational  intoxications. 

A  comprehensive  list  of  substances  that  injure  work  people  would  be 
long  and  impressive.  It  includes  acids,  alkalis,  paraffin,  petroleum, 
phenylhydrazin,  tar,  naphtha,  carbon  bisulphid,  anilin,  the  alcohols, 
benzol,  chlorid  of  lime,  chlorin,  chromium,  formaldehyd,  manganese, 
nitrous  oxid,  picric  acid,  prussic  acid,  pyridin,  sulphuretted  hydrogen, 
and  very  many  others. 

LEAD 

Lead  poisoning  is  one  of  the  most  frequent,  most  serious,  and  most 
insidious  of  all  the  occupational  intoxications.  If  a  pound  of  lead  drops 
on  a  workman's  head  the  catastrophe  is  more  obvious  than  if  minute 
quantities  of  lead  salts  are  taken  into  the  system  day  by  day,  but  the 
poisoning  may  be  as  fatal  as  the  accident.  The  population  at  large  is 
also  frequently  poisoned  with  lead  from  a  variety  of  sources.  Thus  the 
lead  may  be  in  the  drinking-water  as  a  result  of  contact  with  lead  pipes, 
in  canned  goods  from  the  solder,  in  foods  cooked  in  lead-enameled  uten- 
sils, and  from  handling  lead  or  objects  containing  lead. 

Lead  is  a  typical  cumulative  poison.  A  large  amount  may  be  taken 
at  one  time  without  noticeable  effect,  but  small  quantities  ingested  daily 
are  absorbed,  stored  in  the  body,  resulting  in  chronic  poisoning  and  even 
death.  Lead  is  excreted  both  by  the  kidneys  and  the  liver,  and  also  the 
skin.  It  probably  does  not  appear  in  the  urine  except  with  albumin,  that 
is,  lead  can  only  pass  a  damaged  kidney.  The  lead  excreted  by -the  liver 
passes  into  the  intestines  with  the  bile  and  may  be  found  in  the  feces. 
The  elimination  of  the  lead,  however,  is  slow  and  uncertain.  As  much 
as  one  ounce  of  the  acetate  of  lead  has  been  taken  at  one  time  without 
injury.  Older  physicians  frequently  prescribed  the  acetate  of  lead  as 
an  astringent  in  doses  of  10,  20,  or  30  grains.  The  same  amount  of  lead 
distributed  in  minute  doses  and  taken  daily  would,  in  all  likelihood, 
result  in  serious  poisoning.  The  reason  for  this  is  that  when  one  large 
dose  is  taken  only  a  small  quantity  is  absorbed ;  the  rest  is  swept  through 
the  intestines,  but  when  small  quantities  are  taken  at  frequent  intervals 
practically  all  is  absorbed  and  the  metal  accumulates  in  the  tissues,, 
poisoning  especially  the  delicate  nervous  structures. 

The  susceptibility  to  lead  poisoning  varies  greatly.     Of  a  number  of 

^  Zeitschr.  f.  experimentelle  Path,  und  Pliarmakologie,   1910,  LXIII,  p.  242. 


DISEASES  OF  OCCUPATIOIsT  1049 

persons  exposed  to  the  same  conditions  some  are  fatally  poisoned,  others 
suffer  with  mild  plumbism,  and  still  others  escape  entirely.  Young  per- 
sons are  much  more  susceptible  than  old.  Young  adults  suffer  most. 
Women  are  more  susceptible  than  men.  Eecognizing  this  fact,  in  1898 
England  abolished  female  labor  in  the  dangerous  processes  of  white  lead 
manufacture.  The  reasons  for  this  varying  susceptibility  are  only  partly 
understood.  Hyperacidity  of  the  gastric  juice  is  a  predisposing  factor, 
because  the  lead  in  such  persons  is  readily  converted  to  the  soluble 
chlorid  in  the  stomach.  Personal  cleanliness  is  another  important  fac- 
tor, and  workers  in  lead  who  do  not  give  scrupulous  attention  to  cleanli- 
ness of  person  and  clothing  suffer  most.  Persons  who  are  not  particu- 
larly careful  about  cleaning  their  hands  before  eating,  or  who  frequently 
carry  their  fingers  to  their  mouth  and  nose,  run  especial  risks.  Oliver 
has  shown  by  experiments  on  animals  that  alcohol  precipitates  attacks 
of  plumbism,  a  fact  which,  in  the  human  subject,  clinical  experience  has 
again  and  again  confirmed.  There  is  not  the  least  doubt  that  alcoholic- 
intemperance  predisposes  to  lead  poisoning. 

Practically  all  forms  of  lead  are  poisonous,  even  the  metal  itself. 
The  carbonate,  the  oxid,  and  the  chromate  are  the  most  serious  because 
these  are  most  employed  in  the  industries.  The  soluble  salts  are  more 
readily  absorbed  than  insoluble  salts.  The  carbonate  is  so  much  more 
poisonous  than  the  sulphate  that  an  effort  should  be  made  to  eliminate 
the  carbonate  in  all  industries  in  which  this  is  possible. 

In  the  majority  of  cases  of  lead  poisoning  in  the  industries  the  lead 
comes  through  the  air  to  the  victim  as  dust,  sometimes  as  fumes.  Pre- 
ventive measures  must,  therefore,  be  directed  toward  keeping  the  air 
about  the  workmen  free  from  lead.  A  lead  trade  is  dangerous  in  propor- 
tion to  its  dustiness.  Lead  is  usually  taken  into  the  system  from  the 
digestive  tract,  although  absorption  from  the  respiratory  tract  and  even 
through  the  skin  may  occur.  For  many  years  it  was  a  disputed  point 
whether  the  lead  entered  through  the  skin  or  the  intestinal  tract,  but  it  is 
now  conceded  that  the  intestinal  mucosa,  also  that  of  the  mouth,  is  the 
usual  portal  of  entry.  Much  of  the  lead  dust  that  is  a  source  of  lead 
poisoning  is,  in  fact,  swallowed.  Lead  is  also  carried  to  the  mouth  by 
the  fingers  and  in  a  great  variety  of  other  ways. 

The  water-soluble  salts  of  lead  such  as  acetate,  chlorid,  and  nitrate 
may  be  absorbed  through  the  skin,  but  this  is  slow  and  requires  long 
exposure.  It  is  possible  that  the  non-soluble  salts  may  be  changed  by 
contact  with  the  fatty  acids  on  the  skin  into  soluble  compounds.  Lead 
poisoning  may  be  caused  by  absorption  through  the  skin  from  cosmetics 
containing  lead.  Edsall  thinks  skin  absorption  relatively  unim- 
portant. In  this  he  is  in  accord  with  Weyl,  Legge,  Oliver,  and  Sommer- 
feld. 

The  symptoms  of  lead  poisoning  are:  a  blue  line  on  the  gums  (sul- 


1050         HYGIENE  AND  DISEASES  OF  OCCUPATION 

phid  of  lead),  a  diminution  in  tlie  secretion  of  saliva  and  a  sweetish  taste 
in  the  mouth,  colic,  constipation,  weakness,  slowing  of  the  pulse,  increase 
in  blood  pressure,  and  anemia.  The  corpuscles  may  fall  below  50  per 
cent,  and  many  of  the  red  cells  show  a  granular  basophilic  degeneration 
when  stained  with  one  of  the  polychrome  methylene  blue  dyes.  Lead 
palsy  is  very  common.  It  is  a  peripheral  toxic  neuritis  and  usually  af- 
fects a  localized  group  of  muscles  such  as  the  extensor  muscles  of  the 
forearm — painter's  wrist  drop.  The  common  symptoms  are  colic,  con- 
stipation, and  paralysis.  Edsall  calls  attention  to  the  fact  that  enceph- 
alitis, which  expresses  itself  as  an  acute  insanity,  is  a  frequent  mani- 
festation of  lead  poisoning. 

The  early  recognition  of  lead  poisoning  is  essential  to  protect  the 
worker.  The  disease  should  be  recognized  before  the  development  of 
the  lead-line  on  the  gums,  the  basophilic  degeneration  of  the  red  blood 
corpuscles,  or  wrist  drop.  Among  the  earliest  manifestations  of  chronic 
lead  poisoning  is  the  pallor  of  the  skin,  even  out  of  proportion  to  the 
anemia  as  determined  by  the  reddest  of  hemoglobin  and  the  number  of 
red  blood  cells.  The  face  has  a  pinched  appearance  owing  to  wasting 
of  the  fat  under  the  eyes  and  about  the  buccinator  muscles.  General 
muscular  sickness  with  "rheumatic"  pains  in  the  joints,  muscles,  and 
more  particularly  in  the  back  are  of  frequent  occurrence  in  the  early 
sta,ges  of  the  disease.  Among  the  gastro-intestinal  symptoms  are  an- 
orexia, nausea,  constipation  or  constipation  alternating  with  diarrhea. 

Loss  of  appetite  from  whatever  cause  among  workers  exposed  to 
lead  is  always  a  symptom  to  be  taken  seriously  on  account  of  the  in- 
creased absorption  of  lead  w^hen  the  stomach  is  empty.  Colic  sometimes 
associated  with  tenderness,  general  nervousness,  persistent  headaches  and 
dull  mentality  are  also  among  the  earlier  symptoms. 

Paul  ^  studied  the  effects  of  lead  poisoning  on  the  offspring  and 
found  that  of  142  pregnancies  among  women  suft'ering  from  lead  poison- 
ing, only  45  resulted  in  a  viable  child  and  20  of  these  died  the  first  year, 
only  10  surviving  beyond  the  third  year.  Almost  similar  figures  have 
been  published  regarding  the  noxious  influence  of  mercury,  also  of 
alcohol  poisoning  on  the  offspring. 

Fetal  death  and  abortion  is  common  in  maternal  lead  poisoning.  The 
offspring  may  be  affected  when  the  mother  is  normal,  but  the  father 
"leaded."  Cole  and  Bauchhuber  ^  fed  lead  acetate  to  rabbits  and  fowls. 
In  the  rabbits  the  mortality  of  the  young  during  the  first. four  days  after 
birth  was  47.7  per  cent,  for  offspring  of  "leaded"  males,  as  contrasted 
with  29.2  per  cent,  for  offspring  of  normal  males.  The  average  weight 
at  birth  was  48.9  grams  for  the  former  and  59.0  grams  for  the  latter. 

^  Cited  in  G.  C.  Nijhoff's  article  on  "Action  on  Ovum  of  Superfluous  Semen," 
Nederl.   Tijdschr.  v.   Oeneeskunde,  Amsterdam,  II,   No.    16. 

^Cole  and  Bauchhuber:    Proc.  Sor.  E.rprr.  Biol,  and  Med.,  1914. 


DISEASES  OF  OCCUPATION 


1051 


With  Leghorn  hens  the  results  were  similar.  Weller  ^  used  commercial 
white  lead  (basic  carbonate),  which  he  fed  in  capsules  to  guinea-pigs. 
The  experiments  showed  that  paternal  lead  poisoning  in  guinea-pigs  does 
not  result  in  sterility  or  in  stillbirth,  but  in  reduction  of  weight  at  birth, 
and  this  underweight  persists  through  life.  Next  to  this,  the  most  strik- 
ing change  is  the  high  rate  of  mortality  during  the  first  few  days  after 
birth. 

The  character  of  certain  occupations  has  an  influence  on  the  type  of 


Fig.  147. — A  Worker  with  Lead  Oxid,  Showing  Respirator  to  Protect  Himself 
AGAINST  the  Poisonous  Dust.     (Mass.  State  Board  of  Health.) 


lead-poisoning  which  develops.  Thus  Teleky  finds  that,  while  cpmposi- 
tors  in  Vienna  seldom  sufi^er  from  colic  or  from  the  severer  types  of  lead 
poisoning,  they  are  subject  to  an  unusual  extent  to  diseases  of  the  lungs 
and  kidneys.  The  relation  between  tuberculosis  and  chronic  plumbism 
is  shown  in  Hahn's  diagrams  based  on  the  records  of  typographical  trades 
in  Vienna  and  Berlin,  the  curves  of  the  two  diseases  showing  a  remark- 
able parallelism.  Colic  is  said  by  Legge  to  be  most  frequent  among 
workers  in  white  lead,  red  lead,  enameling,  storage-batteries,  coach-paint- 
ing   (which  involves  sandpapering),  while  the  severer  form  with  pa- 

MVeller,  C.  V.:    Jour.  Med.  Research,  1915,  XXXIII,  271. 
The  Effect  on  the  Offspring  of  Lead  Poisoning  in  the  Father:    J.  A.  M.  A., 
Dec.  25,   1915,  LXV,  No.  26. 


1052         HYGIENE  AND  DISEASES  OF  OCCUPATION 

ralysis  is  found  in  l)rass-workers,  plumbers,  printers,  file-r-ntters,  aii'1 
tinsmiths.  The  former  are  very  dusty  trades;  poisoning  occurs  rapidly 
and  encephalopathy  is  more  frequent  than  paralysis. 

Tlie  manner  in  which  lead  is  handled  makes  a  vast  difference  so  far 
as  the  liability  to  plumbism  is  concerned.  Thus  Stiller  found  in  Vienna 
that  carriage  painters  are  ten  to  twenty  times  more  subject  to  lead 
poisoning  than  house  painters.  This  has  been  confirmed  by  Edsall  in 
this  country.  The  reason  for  this  is  that  carriage  painters  apply  a  large 
number  of  coats  of  paint  and  varnish,  polishing  between  each  coat,  and 
thereby  enveloping  themselves  in  dust  which  contains  much  lead ;  fur- 
thermore, carriage  painters  are  required  to  work  indoors.  For  lead  poi- 
soning due  to  water  see  page  920. 

Red  .Lead  (Litharge,  Massicot,  or  Lead  Oxid). — In  the  manufacture 
of  red  lead  the  metal  is  simply  roasted  in  a  reverbcratory  furnace  and 
raked  from  time  to  time.  A  considerable  amount  of  fumes  escapes  from 
the  mouth  of  the  furnace  and  unless  this  is  hooded  and  a  strong  draft 
provided  to  carry  it  away  the  workmen  may  become  poisoned.  The  red 
lead  is  removed  in  large  pieces  and  then  ground,  during  which  process 
quantities  of  fine  dust  are  raised  which  may  also  poison  the  workmen. 

"White  Lead, — Most  of  the  white  lead  is  still  made  by  the  old  Dutch 
method,  which  consists  in  the  transformation  of  metallic  lead  into  the 
white  carbonate  by  a  slow  and  double  process  of  conversion.  Numerous 
earthenware  pots  containing  3  per  cent,  of  acetic  acid  are  placed  on  tan 
in  a  large  three-walled  chamber,  and  upon  these  pots  are  laid  thin  strips 
of  metallic  lead  and  subsequently  planks  of  wood.  Tier  after  tier  of 
pots  resting  on  bark  and  covered  with  metallic  lead  and  wood  are  thus 
superimposed  until  the  chamber,  25  or  30  feet  in  height,  is  filled  to 
within  6  feet  from  the  top.  This  chamber,  known  as  the  "blue"  bed,  is 
kept  closed  for  14  weeks  or  longer.  Fermentation  causes  a  rise  in  tem- 
perature and  a  production  of  carbonic  acid.  The  acetic  acid  acts  upon 
the  lead  and  converts  it  into  acetate  of  lead,  Avhile  the  COg  evolved  from 
the  bark  changes  the  acetate  into  carbonate  or  the  well-known  white  lead 
of  commerce.  The  danger  of  plumbism  occurs  during  the  emptying  or 
stripping  of  what  is  now  called  the  "white"  bed.  If  sufficient  time  has 
not  been  given  for  the  very  soluble  acetate  to  have  become  changed  into 
the  carbonate  the  danger  is  thereby  greater.  During  the  stripping  of 
the  "white"  bed  there  is  a  considerable  quantity  of  dust  raised,  a  large 
part  of  which  is  white  lead,  and  unless  spraying  with  water  is  effectively 
carried  out  the  workmen  cannot  avoid  inhaling  the  dust. 

Dr.  T.  Morison  Legge  found  that  of  1,463  persons  employed  off 
and  on  in  white  lead  works  the  incidence  of  lead  poisoning  was  6  per 
cent,  of  the  average  number  regularly  employed,  and  in  those  casually 
employed  39  per  cent.  This  shows  the  great  risk  of  exposing  unskilled 
labor  in  a  dangerous  occupation. 


DISEASES  UE  OCCUPATION  1053 

In  some  progressive  plants  the  white  lead  is  transferred  mechanically 
from  the  white  beds  to  the  mixing  department,  where  it  is  ground, 
washed  with  water,  and  subsequently  mixed  with  oil,  and  thus  converted 
straightway  into  paint  without  even  being  handled  at  all.  This  greatly 
diminishes  the  danger. 

White  paint  contains  75  per  cent,  of  lead  carbonate  and  25  per  cent, 
of  oil.  The  men  who  mix  the  paint  do  not  suffer  to  any  extent  from 
plumbism,  as  little  dust  is  raised  during  this  process. 

The  Manufacture  of  Pottery  and  Earthenware. — Next  to  the  white 
and  red  lead  industries  the  glazing  of  pottery  and  earthenware  fur- 
nishes the  largest  numbers  of  victims  of  lead  poisoning.  The  lead  is 
contained  in  the  glaze  with  which  such  ware  is  coated  and  the  danger 
occurs  in  cleaning  and  polishing  the  ''biscuit/'  during  which  process 
a  considerable  amount  of  dust  containing  lead  is  raised. 

The  article  to  be  made  is  shaped  and  molded  from  the  clay  or  kaolin 
and  then  placed  in  an  oven  and  fired.  Some  pottery,  such  as  terra  cotta 
and  stoneware,  requires  only  one  firing,  but  all  others  have  to  be  fired 
twice.  After  the  first  firing  the  ware  is  known  as  "biscuit."  The  biscuit 
is  dipped  into  a  liquid  glaze  and  then  fired  again,  which  produces  the 
hard,  smooth,  vitrified  surface. 

A  "non-fritted"  glaze  contains  raw  lead,  that  is,  the  carbonate.  The 
ware  is  dipped  into  the  mixture,  then  dried,  and  each  piece  is  smoothed 
and  cleaned.  During  the  cleaning  of  the  biscuit,  especially  when  pre- 
pared with  a  nonfritted  glaze,  considerable  dust  containing  lead  carbon- 
ate is  raised. 

A  "fritted  glaze"  is  a  compound  of  raw  lead  (carbonate),  silica, 
boric  acid,  etc.,  fused  together  at  a  high  temperature.  This  produces 
a  glass-like  substance  in  which  the  lead  is  rendered  more  insoluble. 
When  ground  and  mixed  with  fine  clay  and  water  it  forms  a  white 
chalky  liquid  into  which  the  biscuit  is  dipped.  The  fritted  glaze  is 
safer  for  the  workmen  than  the  non-fritted  glaze  containing  raw 
lead. 

The  use  of  leadless  glazes  has  been  opposed  by  many  manufacturers, 
but  it  has  been  shown  by  Thorpe  and  Oliver  that  the  largest  proportion 
of  earthenware  can  be  made  without  lead  in  the  glaze.  The  advantages 
of  lead  in  the  glaze  are  that  it  melts  at  a  low  temperature  and  gives  a 
deep  gloss  with  a  delicate  bluish  tint  which  is  generally  admired.  In 
justice  to  the  manufacturers  it  should  be  stated  that  they  have  not  found 
the  leadless  glazes  to  prove  satisfactory. 

In  the  manufacture  of  pottery  the  workmen  are  liable  to  lung  dis- 
eases on  one  hand,  and  lead  poisoning  on  the  other.  This  places  pottery 
manufacture  high  on  the  list  of  dangerous  trades.  "Potter's  rot"  and 
"potter's  asthma"  are  familiar  terms.  The  dangers  may  largely  be 
avoided  by  the  introduction  of  fans  and  strong  drafts  to  carry  away  the 


105^         HYGIENE  AN  J)   DISEASES  OF  OCCUPATION 

dust  from  the  faces  of  the  workers  and  the  use  of  a  fritted  or,  better,  a 
leadless  glaze. 

Besides  the  glazing,  exposure  to  lead  occurs  in  the  decorating  of  pot- 
tery, in  putting  on  dry  colors,  and  in  so-called  erographing,  in  which 
the  lead  colors  are  sprayed  on  the  surface  of  the  pottery. 

Another  danger  in  the  manufacture  of  pottery  is  the  irritating  dust 
which  rises  from  the  finely  ground  flint  in  which  the  biscuit  is  packed 
when  fired. 

File  Cutting. — The  better  grades  of  files  are  cut  by  hand  in  the  fol- 
lowing manner :  The  workman  sits  astride  on  a  "stock."'  In  front  of 
him  is  a  stone  block,  in  the  center  of  which  a  piece  of  steel  bar  called  a 
"stiddy"  is  inserted,  and  in  this  stiddy  is  placed  a  piece  of  metallic  lead 
which  is  called  the  "bed.''  The  lines  are  made  by  striking  with  a  ham- 
mer and  chisel,  each  line  upon  the  file  representing  a  blow  from  the 
hammer.  There  is  a  considerable  quantity  of  dust  given  off  when  the 
file  is  rubbed  with  charcoal  before  it  is  turned.  This  dust  contains  a 
large  proportion  of  lead.  The  lead  is  also  taken  into  the  mouth  from 
the  hands  through  uncleanly  habits  of  the  workmen.  File  cutters  fre- 
quently suffer  from  lead  palsy.^ 

Miscellaneous  Industries. — Layet  computed  that  in  France  111  indus- 
trial processes  involve  the  use  of  lead.  Hamilton  ^  found  70  such  proc- 
esses in  Illinois  in  which  lead  or  its  salts  are  handled  and  which  have 
caused  lead  poisoning  in  recent  times. 

Some  of  the  industries  in  which  lead  poisoning  may  occur  are :  mak- 
ing and  selling  wall  paper,  polishing  brass,  polishing  nickel,  finishing 
cut  glass,  holding  lead-covered  nails  in  the  mouth  while  shingling  a  roof, 
working  with  aluminium  foil  (7  per  cent,  lead),  in  lithography,  zinc 
smelting,  making  ornamental  tiles  with  a  nonfritted  lead  glaze,  wrap- 
ping cigars  in  "tin"  foil,  enameling  bathtubs,  laying  electric  cables,  stop- 
ping the  inequalities  of  wood  with  white  lead  in  making  automobiles, 
assembling  and  recharging  old  storage-battery  plates,  polishing  handles 
of  coffins,  etc.  Lead  poisoning  may  also  be  contracted  from  diamond 
cutting,  the  setting  and  polishing  of  precious  stones,  from  enameling 
iron  plates  and  hollow  ware,  from  electric  accumulator  works,  from 
printing,  type-founding,  type-setting,  and  linotyping,  from  dye  works 
where  yellow  colors  are  got  from  chromate ,  of  lead,  from  house,  coach 
and  ship  painting,  etc, 

PREVENTION 

The  prevention  of  lead  poisoning  rests,  in  the  main,  upon  the  fact 
that  the  lead  comes  to  the  workman  usually  as  dust,  sometimes  as  fumes 
through  the  air,  but  it  must  be  remembered  that  lead  is  also  carried  to 

^  Grotjahn  and  Kamp,  Band  IT,  p.  60. 

V.  A.  M.  A.,  Vol.  LVI,  No.  17,  April  20,  1911,  1240-1245. 


DISEASES  OF  OCCUPATION  1055 

the  mouth  by  deposits  on  the  hands  and  other  objects.  Whether  the  lead 
enters  the  body  by  inhalation,  by  ingestion,  or  through  the  skin  becomes 
more  of  an  academic  than  a  practical  question  so  far  as  prevention  is  con- 
cerned. 

The  first  essential  then  is  to  keep  the  air  which  the  workman  breathes 
and  which  surrounds  him  free  of  lead.  Most  cases  of  lead  poisoning 
could  be  averted  by  a  proper  system  of  ventilation.  Certain  processes 
should  be  carried  on  under  hoods  with  a  strong  draft,  or  in  cabinets,  or 


Fig.  148. — The  Stone  Industry.  The  workman  is  using  a  surfacing  machine  operated 
with  compressed  air.  The  strong  blast  of  air  keeps  the  granite  clean,  but  gives  rise  to 
a  great  amount  of  dust.  Of  the  mineral  dusts  granite  is  generally  considered  as  most 
irritating.     (Mass.  State  Board  of  Health.) 

special  rooms  with  an  air  current  so  arranged  that  the  lead  is  kept  away 
from  the  mouth,  nose,  hands,  and  clothes  of  those  who  are  exposed. 

On  the  part  of  the  workman  the  prevention  of  lead  poisoning  con- 
sists in  cleanliness  of  the  hands  and  of  the  finger  nails,  frequent  bathing, 
and  the  use  of  special  clothing  while  at  work.  Care  must  be  taken  not 
to  carry  the  fingers,  which  may  be  contaminated  with  lead,  to  the  mouth 
and  nose,  and  to  thoroughly  wash  the  hands  before  eating.  Workmen 
should  never  take  their  lunch  in  the  rooms  where  there  is  a  suspicion  of 
lead  in  the  air.  In  the  few  instances  where  the  above  precautions  are  not 
practical  respirators  should  be  worn. 

Cleanliness  is  one  of  the  all-essential  requirements.  A  special  room 
for  the  clothes  of  the  workmen  and  special  overalls  should  be  provided 


1056         HYGIENE  AND  DISEASES  OF  OCCUPATION 

for  those  who  are  exposed  to  lead.  It  is  ignorance  of  the  danger  and  the 
want  of  personal  cleanliness  that  make  casual  labor  in  lead  works  espe- 
cially dangerous.  Even  the  women  who  wash  the  clothes  of  the  workmen 
employed  in  lead  factories  may  sometimes  suffer  from  lead  poisoning. 
Lavatories  should  be  provided  at  the  factory  and  the  hands  should  be 
washed  with  water  containing  a  small  quantity  of  acetic  acid  followed  by 
a  liberal  allowance  of  soap. 

Workmen  should  alternate  employment  and  not  remain  too  long  in 
the  dangerous  departments.  Supplanting  hand  labor  by  machinery 
diminishes  the  number  exposed  to  the  risk.  A  medical  inspection  is  an 
important  preventive  guard  in  educating  the  workmen  and  in  detecting 
mild  and  beginning  cases. 

A  radical  measure  would  be  the  substitution  of  zinc-white  for  lead 
paints.  Zinc  may  be  used  as  a  substitute  for  lead;,  especially  in  indoor 
work;  in  fact  this  has  been  required  by  law  in  France.  White  lead  ap- 
pears to  be  superior  to  zinc  for  outdoor  work. 

Keeping  down  the  hyperacidity  of  the  gastric  juice  is  believed  to  be 
a  good  preventive  measure.  This  may  be  accomplished  in  part  by  taking 
a  bland  oil  or  drinking  milk  at  intervals  during  work.  Milk  also  acts  by 
fixing  the  HCl  of  the  gastric  juice  by  the  milk  proteins.  The  milk  should 
be  taken  between  meals  (say  10  a.  m.  and  4  p.  m.)  for  in  some  persons 
there  is  considerable  secretion  of  gastric  juice  in  the  empty  stomach. 

The  Massachusetts  State  Board  of  Health  issues  the  following  pro- 
tective measures  against  lead  poisoning : 

The  poison  gains  entrance  into  the  system: 

( 1 )  By  swallowing  minute  particles  of  lead. 

(2)  By  inhaling  lead  dust  or  the  fumes  of  lead  in  a  molten  state, 
or  the  vapor  of  lead  in  a  fused  state. 

(3)  By  absorption  from  the  skin  in  handling  lead. 

Advice  to  Employees 

(1)  General  personal  cleanliness  is  of  the  first  importance. 

(2)  Thoroughly  clean  your  hands  before  touching  food  and  before 
leaving  the  workroom. 

(3)  Thoroughly  rinse  your  mouth  before  eating. 

(4)  Take  good,  nutritious  food  and  plenty  of  milk, 

(5)  Take  a  substantial  breakfast;  an  empty  stomach  is  more  sus- 
ceptible to  the  poisonous  effects  of  lead. 

(6)  Never  eat  at  your  work.  Eat  your  luncheon  outside  of  the 
workroom  if  possible;  if  not,  in  a  part  of  the  room  away  from  the  lead. 
Never  smoke  or  use  tobacco  in  any  form  while  at  work. 

(7)  Avoid  all  excesses;  alcoholic  beverages  are  especially  injurious. 

(8)  Wear  overalls  or  a  long  coat  at  your  work;  also  a  cap  or  some 


DISEASES  OF  OCCUPATION  1057 

head  covering.     Whenever  practicable  wear  gloves  when  lead  is  to  be 
handled. 

(9)  Persons  working  in  white  lead  or  other  powdered  compounds 
of  lead  should  always  wear  a  respirator  while  at  work.  Cause  as  little 
dust  as  possible. 

(10)  Consult  a  physician  at  the  first  sign  of  ill  health. 


Advice  to  Employers 

(1)  Provide  washing  facilities,  lockers,  and  a  place  for  the  em- 
ployees to  eat  luncheons  away  from  lead. 

(2)  Provide  respirators  for  all  the  workers  who  have  to  handle 
white  lead  or  other  powdered  compounds  of  lead. 

(3)  The  floors  of  the  workrooms  and  benches  at  which  men  work 
should  be  cleaned  daily  after  thoroughly  moistening  them. 

(4)  These  regulations  should  be  posted  in  a  conspicuous  place  in 
the  workroom. 

PHOSPHORUS 

There  are  two  kinds  of  phosphorus:  (1)  the  white  or  yellow,  dis- 
covered by  Brandt  of  Hamburg  in  1669,  (2)  the  red  or  amorphous,  dis- 
covered by  Schroter  of  Vienna  in  1845.  The  amorphous  phosphorus  is 
obtained  from  the  white  phosphorus  by  exposing  it  in  a  closed  vessel 
for  some  time  to  a  temperature  of  250°  C.  The  white  or  yellow  phos- 
phorus is  poisonous  and  has  been  the  cause  of  much  suffering  in  the 
match  industry.  The  red  or  amorphous  phosphorus  is  practically  not 
poisonous.^ 

Three  kinds  of  matches  are  made :  ( 1 )  the  safety  match,  which  con- 
tains no  phosphorus  and  is  harmless.  The  match  heads  contain  potas- 
sium chlorate  or  chromate  and  other  compounds  rich  in  oxygen  from 
which  the  oxygen  required  to  induce  conflagration  is  evolved.  The  paste 
applied  to  the  side  of  the  match-box  contains  antimony  sulphid  and  red 
phosphorus:  (2)  the  strike-anywhere  match  contains  the  poisonous  white 
phosphorus  in  the  head,  and  in  addition  glue,  chlorate  of  potassium, 
powdered  glass,  and  magenta  or  some  other  coloring  agent.  The  paste, 
or  composition,  contains  on  an  average  5  per  cent,  of  phosphorus.  It  is 
in  mixing  this  paste,  especially  when  done  by  hand  in  open  vessels,  and 
also  in  dipping  the  wooden  splints,  that  the  work-people  are  exposed  to 
fumes  that  become  a  menace  to  health:  (3)  the  strike-anywhere  match 
made  with  the  non-poisonous  sesquisulphid  of  phosphorus.  The  paste 
from  which  these  non-poisonous  matches  are  made  is  as  follows : 

^Phosphorous  Poisoning  in  the  Match  Industry,  by  J.  B.  Andrews,  Bull.  86, 
U.  8.  Bureau  of  Labor. 
35 


1058 


HYGIENE  AND  DISEASES  OF  OCCUPATION 


Sesquisulphid  of  phosphorus 6  parts 

Chlorate  of  potassium 24  " 

Oxid  of  zinc 6  " 

Red  ochre 6  " 

Powdered  glass 6  " 

Glue 18  " 

Water 34  " 

Sometimes  these  matches  also  contain  from  3  to  4  per  cent,  of  red 
phosphorus  which  prevents  the  formation  of  unstahle  suhsulphids.    These 


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Fig.  149. — Workmen  Exposed  to  Zinc  Fumes  in  Brass  Casting,  Causing  a  Condi- 
tion Known  as  "Brass-founder's  Ague." 


matches  have  been  used  exclusively  for  the  last  12  years  in  France.  In 
our  country  the  strike-anywhere  match  made  with  poisonous  white  phos- 
phorus until  1913  constituted  the  principal  output. 

When  pure,  phosphorus  is  colorless  and  transparent,  b-ut  when  ex- 
posed to  the  light  it  becomes  yellowish.  The  white  and  yellow  forms  are 
extremely  poisonous;  the  red  or  amorphous  phosphorus  can  be  handled 
with  impunity.  Eed  phosphorus  does  not  take  fire  when  rubbed  on  a 
rough  surface.  It  is  non-volatile  and  when  swallowed  is,  comparatively 
speaking,  non-poisonous.  One  to  3  grains  of  white  phosphorus  will 
cause  death.  The  fumes  from  white  or  yellow  phosphorus  are  rich  in 
phosphorus  oxids  and  these  are  absorbed  in  various  ways.     Professor 


DISEASES  OF  OCCUPATION  1059 

Thorpe  exposed  decayed  human  teeth  to  the  fumes  of  phosphorus  for  12 
hours  and  he  found  that  they  lost  0.37  per  cent,  of  their  weight  and  that 
carious  teeth,  when  exposed  to  a  dilute  solution  of  phosphoric  acid  (1 
per  cent.),  lost  8.9  per  cent,  of  their  original  weight.  The  atmosphere 
of  an  ill-ventilated  match  factory  in  which  the  white  or  yellow  phos- 
phorus is  used  reeks  with  the  garlicky  odor  characteristic  of  phosphorus. 
The  fumes  become  dissolved  in  the  saliva  of  the  moutli  and  exercise  a 
solvent  action  upon  the  teeth  of  persons  inhaling  this  poisonous  atmos- 
phere several  hours  of  each  working  day.  The  poison  also  clings  to  the 
fingers  and  hands  of  the  work-people.  Thus  Oliver  found  the  hands  of  a 
boxer  to  be  deeply  stained  by  the  dye  given  off  by  the  heads  of  the 
matches,  to  emit  a  characteristic  garlicky  odor  and  glow  in  the  dark. 
The  phosphorus  is  also  absorbed  by  the  drinking-water  if  exposed. 

The  principal  and  characteristic  disease  produced  by  white  or  yellow 
phosphorus  is  necrosis  of  the  jaw,  known  as  "phossy  jaw."  This  is  a 
localized  inflammatory  infection  of  the  jaw-bone  extremely  painful  in 
the  early  stages,  which  runs  a  chronic  course  and  invariably  ends  in  the 
localized  death  of  the  bone.  The  gums  become  swollen  and  the  jaw-bone 
painful;  sooner  or  later  pus  forms  and  although  the  teeth  are  ex- 
tracted the  pain  continues.  The  inflammation  gradually  extends  to  the 
bone. 

It  is  probable  that  the  phosphorus  fumes  and  the  phosphoric  acid 
acting  through  decayed  teeth  set  up  inflammation,  thereby  allowing 
microorganisms,  always  present  in  the  mouth,  to  carry  the  morbid 
process  deeper.  Lewin  of  Berlin "  does  not  believe  that  it  is  primarily 
necessary  for  a  Inciter  match-maker  to  have  decayed  teeth,  for  the  phos- 
phorus fumes,  in  his  opinion,  inflame  the  gums  in  the  first  instance,  and 
as  a  consequence  there  is  induced  a  septic  gingivitis,  which  is  followed  by 
disease  of  the  bone.  Other  effects  of  phosphorus,  though  less  frequent, 
are  phosphorism,  which  is  a  general  cachectic  condition  met  with  prin- 
cipally in  female  workers,  and  characterized  by  anemia,  dyspepsia,  al- 
buminuria, and  a  tendency  to  bronchitis.  Fragilitas  ossium  is  another 
condition  met  with  in  phosphorus  workers.  According  to  Dearden,  the 
bones  of  match-dippers  contain  an  excess  of  phosphoric  acid  which  com- 
bines with  the  preexisting  neutral  phosphate  of  lime  to  form  a  slightly 
acid  salt  and  thereby  causes  excessive  brittleness  of  the  bones. 

The  prevalence  of  phossy  jaw  may  be  gleaned  from  the  fact  that  in 
Great  Britain  somewhat  less  than  1  per  cent,  of  the  match-makers  have 
suffered  from  it.  In  Switzerland  the  incidence  was  formerly  1.6  to  3 
per  cent.,  and  in  France  3  to  3  per  cent.  In  this  country  the  subject 
was  investigated  by  the  Bureau  of  Labor,  who  found  that  there  are  about 
3,500  employees  in  15  of  the  17  match  factories  in  the  United  States; 
of  3,383  whose  occupation  was  specified  65  per  cent,  were  exposed  to 
phosphorus  fumes.     It  was  also  found  that  95  per  cent,  of  1,395  so  ex- 


lOGO  liY(JlENE  AM)   DISEASES  OF  OCCUPA^I'lOiN' 

])(),sed  are  women.     An  intensive  stiuly  of  tiireo  factories  was  made  and 
82  eases  of  necrosis  were  discovered. 

Several  years  ago  the  Belgian  govcrjiment  offered  a  prize  of  50,000 
francs  to  any  person  who  would  invent  a  safety  strike-anywhere  match 
free  from  white  phosphorus.  The  problem  was  solved  by  Sevene  and 
Cahan  of  France,  who  demonstrated  that  the  sesquisulphid  of  phosphorus 
would  accomplish  all  that  white  phosphorus  does  without  causing  poison- 
ing. The  sesquisulphid  is  an  almost  inodorous  powder  and  is,  practically 
speaking,  nonpoisonous.  It  contains  a  trace  of  red  or  amorphous  phos- 
phorus. Since  the  introduction  into  France  of  the  manufacture  of  the 
sesquisulphid  match  there  has  not  been  in  the  factories  of  that  country, 
where  the  manufacture  of  matches  is  a  state  monopoly,  one  case  of  phos- 
phorus poisoning,  nor  has  there  been  any  explosion  or  fire  in  any  of  the 
match  works.  It  has  been  found  that  the  sesquisulphid  of  phosphorus 
acts,  in  some  instances,  as  an  irritant,  causing  conjunctivitis  and  edema 
of  the  eyelids,  also  eczema  of  the  skin.  This  may  be  obviated  by  bathing 
the  eyes  and  douching  the  nostrils  twice  a  day  before  leaving  the  factory 
with  an  alkaline  solution  of  bicarbonate  of  soda. 


PREVENTION 

The  prevention  of  phosphorus  necrosis  consists  in  the  substitution  of 
the  sesquisulphid  for  the  poisonous  white  and  yellow  forms.  Even 
stringent  regulations  will  not  protect  those  who  have  to  work  with  the 
white  or  yellow  phosphorus.  The  experience  of  Great  Britain  is  espe- 
cially noteworthy.  In  1888  Great  Britain,  after  a  thorough  investiga- 
tion of  the  conditions,  made  stringent  regulations  coupled  with  an 
efficient  inspection,  but  phossy  jaw  was  not  prevented,  and  in  1908  the 
use  of  white  phosphorus  was  prohibited.  White  phosphorus  was  pro- 
hibited by  Finland  in  1872  and  in  Denmark  2  years  later,  since  which 
time  no  case  of  phosphorus  necrosis  has  occurred  in  these  countries. 
France  prohibited  its  use  in  1897,  Switzerland  in  1898,  the  Netherlands 
in  1901,  and  in  1905  the  International  Association  for  Labor  Legislation 
secured  a  treaty  providing  for  the  prohibition  of  the  making  and  selling 
of  matches  made  of  white  phosphorus,  which  treaty  was  signed  by  France, 
Denmark,  Germany,  Italy,  Switzerland,  the  Netherlands,  and  Great 
Britain.  This  country  has  grossly  neglected  to  protect  its  workmc:i 
and  has  only  recently  taken  action  upon  the  serious  conditions  demon- 
strated by  John  B.  Andrews,  Secretary  of  the  American  Association  for 
Labor  Legislation.^ 

Phosphorus  poisoning  may  in  part  be  prevented  by  a  medical  ex- 

*  Congress  passed  a  prohibitive  tax  on  poisonous  phosphorus,  April  9,  1912; 
effective  June,  1913.  An  act  to  provide  for  a  tax  upon  white  phosphorus  matches 
and  for  other  purposes.      [Public  Doc.  No.   118,  11.  Pv.  20842.] 


DISEASES  OF  OCCUPATION  lOGl 

aiiiiiiation,  special  attention  being  paid  to  tlic  state  of  the  teeth.  The 
services  of  a  dentist  are  essential.  Personal  cleanliness  and  the  use  of 
mouth  washes  are  helpful.  The  workroom  should  be  well  ventilated 
and  fans  should  be  kept  running  to  withdraw  all  fumes  away  from 
the  faces  of  the  workers.  Washing  accommodations  should  be  ample,  hot 
and  cold  water  should  be  provided,  along  with  plenty  of  soap  and  towels. 
Persons  sometimes  commit  suicide  by  dissolving  the  white  or  yellow 
phosphorus  from  match  heads  and  drinking  the  solution.  This  is  not 
possible  in  the  case  of  matches  made  with  the  red  or  amorphous  phos- 
phorus or  the  sesquisulphid. 

ARSENIC 

Arsenic  acts  as  an  irritant  to  the  skin  and  mucous  membranes,  set- 
ting up  conjunctivitis,  coryza,  eczema,  and  ulcerations;  it  also  produces 
general  poisoning,  causing  anemia  and  neuritis;  vomiting,  headache, 
swollen  eyelids,  etc.  Arsenical  neuritis  is  particularly  severe  and  often 
serious.  In  the  industries  arsenical  poisoning  is  found  among  workers 
in  the  manufacture  of  Scheele's  green,  in  the  mannfacture  and  use  of 
wall  papers  and  artificial  flowers  containing  arsenical  coloring  agents, 
during  the  packing  of  white  arsenic,  and  in  reduction  works  of  arsenic 
mines. 

Arsenic  is  found  in  wall-paper,  box  papers,  card-board,  painted  toys, 
various  articles  of  wearing  apparel,  such  as  gloves,  hosiery,  ribbons, 
calico,  hat  linings,  worsted ;  in  artificial  flowers,  carpets,  furniture,  cheap 
wines,  confectionery,  etc.  The  forms  in  which  it  is  used  include  white 
arsenic,  arsenite  of  copper,  aceto-arsenite  of  copper,  sulphid  of  arsenic, 
arsenate  of  aluminium,  arsenical  anilins  and  other  dyes.  The  arsenic 
colors  are  not  only  green  but  red,  blue,  yellow,  drab,  brown,  etc.,  de- 
pending upon  the  compoimd  of  arsenic  used. 

Workers  in  arsenic  suffer  from  painful  redness  of  the  eyes  and  from 
eczema  of  the  eyelids.  Men  employed  in  the  manufacture  of  Scheele's 
green  (arsenite  of  copper)  frequently  have  painful  ulcers  on  their 
fingers  or  other  portions  o£  the  body  where  the  dust  collects.  Smelters 
Sometimes  suffer  from  "arsenic  pock,"  an  irritation  of  the  skin  due  to 
the  action  of  the  very  fine  dust  upon  the  perspiring  skin.  The  bronchitis 
from  which  workers  about  smelting  works  suffer  has  been  attributed 
partly  to  the  fumes  given  off  by  the  raw  material  and  partly  to  the  rather 
large  amounts  of  sulphur  contained  in  the  fumes.  Men  employed  in 
removing  vitriol  solution  from  the  depositing  tanks  in  copper  works 
occasionally  suffer  in  consequence  of  the  inhalation  of  arsenuretted 
hydrogen  gas. 

Arsenic  is  also  used  in  curing  furs.  The  Massachusetts  law  forbids 
arsenic  to  exceed  1  grain  per  square  yard,  but  analyses  reveal  that  it 
often  reaches  170  grains.     Out  of  42  samples  of  fur  recently  examined 


10G2  HYCJTENE  AND  DISE.VSES  OF  OCCUPATION 

in  America  11  were  found  licaxily  Idudcil  willi  arsouic.  'i'lic;  pf(;s(;iic" 
of  such  large  quantities  of  arsenic  in  furs  that  are  worn  or  in  rugs  for 
rooms  must  be  a  source  of  danger.  Paper  hangers,  milliners  and  others 
who  handle  articles  containing  arsenic  may  be  poisoned  thereby,  or  per- 
sons who  wear  fabrics  loaded  with  arsenic,  or  who  ((nne  in  contact  Avith 
the  poison  in  other  ways. 

From  wall  paper  the  arsenic  may  be  absorbed  either  as  solid  particles 
detached  from  the  paper  or  as  a  volatile  gas  formed  from  arsenical  or- 
ganic matter  by  the  action  of  several  moulds,  notably  PeniciUium  hrevi- 
caule,  Mucor  mucedo,  etc.  (Gosio.)  For  the  liberation  of  the  volatiU- 
arsenical  compounds  moisture  and  a  certain  amount  of  heat  (60°  to  95° 
F.)  are  necessary.  The  volatile  compound,  according  to  Sanger,  is  prob- 
ably an  organic  derivative  of  arsenic  pentoxid.  In  wall-paper  thv^ 
arsenic  is  fixed  by  means  of  glue  or  simple  sizing,  and  may  be  dislodged 
by  the  slamming  of  doors,  brushing,  or  air  currents.  Glazed  papers 
are  less  likely  to  give  off  arsenical  dust  than  the  unglazed.  A  paper 
may  contain  as  much  as  11.6  grams  of  white  arsenic  per  square  meter. 
An  ordinary  sized  room  decorated  with  such  paper  may  contain  a  pound 
of  white  arsenic. 

Arsenic,  as  well  as  other  irritants,  is  believed  to  predispose  the  tissues 
to  growths  of  a  cancerous  nature. 

MERCURY 

Mercurial  poisoning  ^  may  be  contracted  by  workmen  employed  in  ex- 
tracting mercury  from  cinnabar  (sulphid  of  mercury),  in  which  it  is 
usually  found  in  nature.  The  ore  is  simply  roasted  and  the  mercury 
volatilizes  and  readily  condenses  in  metallic  form.  Mercury  volatilizes 
at  a  low  temperature  and  it  is  this  circumstance  which  creates  much  of 
the  danger  to  those  who  work  with  this  substance,  especially  men  who 
work  in  a  closed  and  heated  atmosphere  containing  the  vapor  given  off 
by  the  metal.  Mercury  is  absorbed  by  the  digestive  system,  the  respira- 
tory tract,  and  also  through  the  skin.  As  an  instance  of  the  absorption 
of  mercury  though  the  skin  Edsall  cites  two  cases  in  dentists  who  were 
poisoned  as  a  result  of  the  custom  found  in  many  dentists  of  working 
up  their  amalgam  in  the  palms  of  their  hands. 

The  occupations  in  which  mercury  is  used  and  in  which  mercurial 
poisoning  occurs  are:  the  separation  of  gold  and  silver  from  their  re- 
spective ores,  which  is  done  by  means  of  an  amalgam;  the  manufacture 
of  incandescent  lamps,  in  which  mercury  pumps  are  used  to  create  o 
vacuum;  in  barometer  and  thermometer  making;  in  felt-hat  and  fur 
dressing,  in  which  mercuric  nitrate  is  used ;  in  water-gilding,  where  an 

^Eeport  on  Mercurial  Poisoning  in  the  Industries  of  New  York  and  Vicinity: 
L.  W.  Bates,  National  Civic  Federation,  1912. 


DISEASES  OF  OCCUPATION  1063 

amalgam  of  gold  or  silver,  after  having  been  applied  to  an  object,  is 
heated  and  the  mercury  driven  off;  and  other  industries. 

The  New  York  and  'New  Jersey  section  of  the  National  Civic  Federa- 
tion in  three  months'  time  found  60  cases  of  mercurial  poisoning,  a 
nervous  disease  called  in  the  trade  "the  shakes,"  among  the  hat  makers 
of  Brooklyn,  Newark,  and  Orange  as  a  result  of  the  mercury  salts  used 
in  preparing  felt. 

The  symptoms  of  mercurial  poisoning  are :  anemia,  headache,  dizzi- 
ness, tremor  of  the  muscles,  especially  the  tongue  and  limbs,  fetid  breath, 
soft,  swollen,  and  ulcerated  gums,  and  loosening  of  the  teeth.  The  sub- 
maxillary and  other  glands  of  the  neck  become  painful  and  the  secretion 
of  saliva  excessive.  Erethism  and  apprehensiveness  are  common;  in 
severe  cases  depression  and  melancholia.  A  persistent  and  apparently 
causeless  diarrhea  is  frequently  a  symptom  of  mercurial  poisoning. 

PREVENTION 

The  prevention  of  mercury  poisoning  is  almost  a  direct  counterpart 
of  the  prevention  of  lead  poisoning.  The  air  must  be  kept  free  of  mer- 
cury, and  this  can  be  accomplished  by  proper  systems  of  ventilation,  by 
the  use  of  hoods  with  forced  draft  and  other  devices  to  keep  the  mercury 
fumes  away  from  the  workmen.  Eubber  gloves  may  be  worn  to  prevent 
absorption  through  the  skin  and  also  to  prevent  the  carrying  of  the 
mercury  to  the  mouth.  Here  again  scrupulous  cleanliness  in  and  after 
leaving  the  workroom,  a  change  of  clothing,  and  washing  the  hands 
before  eating  are  essential. 

Other  metallic  poisons  found  in  the  industries  are  antimony,  brass, 
chromium,  manganese,  platinum,  silver,  vanadium,  etc. 

CARBON  MONOXID 

Carbon  monoxid  is  a  colorless,  inodorous,  and  highly  poisonous  gas. 
It  burns  with  a  pale  blue  flame.  It  is  one  of  the  products  of  the  incom- 
plete combustion  of  illuminating  gas,  also  of  coal  and  explosives.  It  is 
met  with  in  coal  mines  and  other  subterranean  galleries  where  blasting 
has  been  effected  by  dynamite  and  gun-powder.  It  forms  7  to  10  per 
cent,  of  ordinary  illuminating  gas  (coal  gas)  and  30  per  cent,  of  water 
gas.  It  is  the  source  of  the  blue  flame  seen  on  the  surface  of  an  ordinary 
coal  -fire.  The  gas  is  given  off  in  quantities  from  coke  ovens ;  it  is  evolved 
from  blasting  furnaces  in  the  smelting  of  iron,  especially  during  the 
charging  of  furnaces  and  their  tapping.  Carbon  monoxid  frequently  re- 
mains in  the  furnace,  and  workmen  who  enter  such  a  furnace  in  order 
to  clean  it  may  be  overcome.  In  England  the  law  requires  two  workmen 
to  clean  furnaces ;  one  standg  by  in  case  of  accident.     Carbon  monoxid  is 


1064         HYCIIKNK  AND  DISKASI^^S  OF  OCCUrATJON 

also  evolved  from  hot-water  heaters;  in  the  Leblanc  process  of  soda 
manufacture ;  in  cement  and  brick  works,  etc. 

The  poisonous  properties  of  carbon  monoxid  are,  according  to  Hal- 
dane,  due  to  the  great  affinity  it  has  for  the  hemoglobin  of  the  red 
corpuscles.  It  has  from  140  to  350  times  greater  chemical  affinity  for 
hemoglobin  than  oxygen.  It  forms  carbon  monoxid  hemoglobin,  a  more 
stable  compound  than  oxyhemoglobin,  and  therefore  prevents  the  oxygen 
being  given  to  the  tissues.  When  the  percentage  of  carbon  monoxid  rises 
to  0.4  the  atmosphere  becomes  dangerous  to  animal  life.  (See  page 
721.) 

The  inhalation  of  carbon  monoxid  causes  headache  and  a  sense  of 
loss  of  power  in  the  lower  extremities.  It  is  this  circumstance  which 
explains  many  of  the  cases  of  fatal  poisoning  in  confined  spaces.  There 
are  also  dizziness,  throbbing  of  the  temples,  ringing  in  the  ears,  a  sense 
of  lassitude,  and,  in  severe  cases,  convulsions  and  loss  of  consciousness. 
The  inhalation  of  small  quantities  also  leads  to  delusions  and  other  men- 
tal symptoms.  If  the  gas  enters  a  bedroom  and  is  inhaled  by  persons 
who  are  asleep  the  sleep  only  becomes  deeper  and  profound  narcosis  is 
developed  from  Mdiich  there  may  be  no  awakening. 

Oliver  gives  the  following  illustration  of  the  subtle  poisoning  by 
carbon  monoxid  at  Pel  ton  Fell,  a  mining  village  in  Durham  County. 
Some  shale  which  had  been  tipped  at  the  edge  of  a  ravine  caught  fire. 
The  carbon  monoxid  gas  given  off  during  the  combustion  traveled 
through  the  soil  and  entered  two  houses  in  different  streets,  full  30 
feet  away,  causing  the  death  of  two  elderly  people.  It  is  to  the  breath- 
ing of  this  gas  during  sleep  that  the  death  of  tramps,  drawn  to  the  coke 
ovens  by  their  inviting  warmth  on  a  winter's  night,  is  attributed.  I 
have  already  instanced  the  case  of  death  from  carbon  monoxid  resulting 
from  the  imperfect  operation  of  a  gas  water-heater.     (See  page  734.) 

HYDROGEN  SULPHID 

Hydrogen  sulphid  is  an  extremely  poisonous  gas  causing  death  in- 
stantaneously if  inhaled  in  large  quantities.  In  smaller  amounts  the 
symptoms  caused  are  nausea,  vertigo,  headache,  general  malaise,  all  of 
which  soon  disappear  if  the  workman  goes  into  the  open  air.  There  are 
only  a  few  industrial  undertakings  in  which  hydrogen  sulphid  is  met 
with,  such  as  chemical  and  gas  works;  the  black  bronzing  of  metals  by 
means  of  sulphid  of  arsenic ;  the  cleaning  of  boilers ;  in  certain  processes 
of  soap  making  where  large  quantities  of  fat  are  decomposed;  in  the 
preparation  of  Prussian  blue;  during  the  decomposition  of  ferrocyanid 
of  potassium  by  sulphate  of  iron.  In  nature  hydrogen  sulphid  is  one  of 
the  products  formed  during  the  putrefaction  of  organic  matter  contain- 
ing sulphur.     T1io  gas  may  therefore  be  found  about  privies,  tlio  mud 


DISEASES  OF  OCCUPATION  10G5 

of  marshes,  and  collections  of  filth  and  manure,  but  in  quantities  too 
small  to  seriously  influence  health.     (See  page  727.) 

Benzol  or  benzene  is  one  of  the  coal-tar  distillates,  and  is  used  either 
pure  or  as  commercial  benzene,  which  contains  such  impurities  as  xylene 
and  toluene.  Benzene  is  used  as  a  solvent  for  rubber,  also  in  the  pro- 
duction of  rubber,  resin,  iodin,  phosphorus,  sulphur  and  fats ;  and  in  the 
dyeing  industry. 

Benzene  enters  the  body  as  a  vapor,  irritates  the  respiratory  tract, 
and  produces  acute  and  chronic  poisoning.  In  acute  poisoning  the  symp- 
toms are  of  respiratory  and  nervous  origin  and  range  from  cough,  ver- 
tigo, tinnitus,  vomiting,  perspiration  and  pruritus,  to  cyanosis,  irregular 
pulse,  anesthesias,  delirium,  convulsions,  coma  and  death.  In  the  chronic 
form  there  are  purpuric  hemorrhages  from  the  mucous  membranes  of 
the  mouth  and  nose  and  into  the  skin,  fatty  degeneration  of  the  heart, 
kidneys  and  liver,  anemia,  an  extraordinary  leukopenia  and  death. 

Benzene  has  been  taken  as  a  type  of  the  volatile  hydrocarbons,  such 
as  naphtha,  gasolene,  nitrobenzol,  anilin,  and  other  coal-tar  derivatives. 

Anilin. — Industrial  poisoning  from  anilin  and  substances  closely 
allied  to  it  is  well  known  in  Germany  and  in  Great  Britain.  It  is  just 
beginning  to  be  known  in  the  United  States,^  where  it  has  already  been 
the  cause  of  many  cases  of  poisoning  among  men  engaged  in  the  manu- 
facture of  rubber  goods,  in  reclaiming  rubber  from  scrap,  in  making 
anilin  from  benzene,  and  in  using  certain  washes  for  press  rollers.  It 
also  occurs  in  the  die  industry.  Anilin  causes  the  formation  of  methemo- 
globin,  and  poisoning  may  take  place  through  the  skin  or  the  lungs.  It  is 
commonly  called  "the  blues"  on  account  of  the  cyanosis  produced.  Expo- 
sure to  the  fumes  need  not  be  excessive  nor  long  continued  to  bring  about 
serious  symptoms  in  the  susceptible.  Yomig  men  are  more  susceptible 
than  the  old  or  middle-aged,  blonds  than  dark-haired  men,  heavy  drinkers 
than  the  temperate.  Hot,  humid  weather,  heated  rooms  and  poor  ventila- 
tion are  important  factors  in  the  production  of  acute  anilin  poisoning. 

Early  recognition  of  anilin  poisoning  is  of  prime  importance,  so  that 
the  sufferer  may  be  withdrawn  from  the  danger  of  further  exposure. 
Men  working  constantly  in  anilin  seem  to  acquire  a  certain  amount  of 
tolerance  to  it,  but  chronic  poisoning  may  result  apparently  from  cumu- 
lative effect.  After  symptoms  of  poisoning  have  once  manifested  them- 
selves, the  individual  is  usually  hypersensitive  to  the  fumes. 

Other  toxic  gaseous  vapors  and  fumes  occurring  more  or  less  com- 
monly in  industrial  processes  are:  Acetaldchyd,  acrolein,  ammonia,  amyl 
acetate,  amyl  alcohol,  anilin  and  its  oils,  hydrogen  sulphid,  carbon 
monoxid,  carburetted  hydrogen,  chlorin,  diazomethane,  dimethyl  sul- 
phate, dinitrobenzol,  ether,  ethyl  nitrate,  formaldehyd,  hydrocyanic  acid 

^  Luce  and  I-Tainiltoii :  '■Industrial  Anilin  PDisoning  in  the  U.  S."  J.  A.  M.  A., 
May  6,   1910,  LXVI,  No.   19,  pp.   1441-144.5. 


1066         TTY(;iK.\l<]  AXI)  r)ISIv\SI':S  OK  0(J(Jll'A'ri()iNr 

and  cyanids,  lydol  and  tritoii,  metliyl  alcohol,  rmplitlia  and  gasoline, 
nitrobenzol,  nitrous  gases,  phosgene,  phosphorus,  phosphorated  hydro- 
gen, sulphur  and  sulphur  dioxid,  sulphuretted  hydrogen,  turpentine  and 
many  others.  Only  a  few  of  these  have  been  discussed  as  examples.  See 
also  poisonous  gases  in  the  atmosphere,  page  721. 


DUSTY  TRADES ^ 

Dust  is  the  great  enemy  of  the  workman.  Much  ill  health  is  caused 
by  the  inhalation  of  dust,  some  of  which  is  also  injurious  when  ingested 
and  some  of  which  is  irritating  to  the  skin.  Dust  of  all  kinds,  both 
organic  and  inorganic,  is  met  with  in  the  various  industries.  Organic 
dust  is  usually  less  irritating  and  dangerous  than  inorganic  dust,  which 
becomes  harmful  particularly  when  the  particles  are  sharp  and  therefore 
irritating.  The  principal  trades  and  occupations  in  which  excessive 
amounts  of  dust  are  found  are :  all  forms  of  grinding  and  many  processes 
of  polishing  and  cleaning;  the  textile  industries;  in  the  lead,  copper, 
and  iron  trades  irritating  and  poisonous  dusts  are  raised;  also  in  pottery 
works  and  masonry,  and  in  the  handling  of  leather,  skins,  feathers,  wool, 
cotton,  wood,  paper,  tobacco,  cement,  cutting  diamonds  and  other  precious 
stones;  emery,  glass,  horn,  bone  and  shell,  grain  and  flour,  etc.  The 
amount  of  dust  may  be  very  great ;  thus  Hesse  found  in  one  cubic  meter 
of  air  the  following  amounts  of  dust  in  the  occupations  named: 

Felt  hat  factory 175  milligranis 

An  old  flour  mill 48 

A  new  flour  mill 4  " 

Mechanical  knitting 3  " 

Sculpturing 9  " 

A  paper  factory 4-25  " 

Iron  works 72-100  " 

A  coal  mine 14  " 

A  living  room 0  " 

The  kinds  of  dust  vary  greatly  in  their  hygienic  significance.  Some 
are  poisonous,  some  act  as  mechanical  irritants.  The  principal  poisonous 
dusts  found  in  the  industries  are  lead,  mercury,  arsenic,  phosphorus, 
and  zinc;  less  often  substances  from  tobacco,  wood,  dyes,  and  chemical 
works.  The  dust  particles  which  act  by  mechanical  irritation  are  espe- 
cially the  hard,  irregular  particles  with  sharp  edges  from  iron,  steel,  and 
other  metals;  from  granite,  basalt,  or  marble;  while  those  from  coal, 
chalk,  and  plaster  of  paris  are  less  irritating. 

According  to  Sommerfeld  the  following  proportion  of  persons  per 

^  See  also  page  713.  , 


DISEASES  OF  OCCUPATION"  1067 

thousand  in  the  various  dusty  occupations  mentioned  die  of  pulmonary 
tuberculosis :  ^ 

Occupation  without  dust  production 2 .  39 

With  dust  production 5 .  42 

With  porcelain  dust 14 . 0 

With  iron  dust 5 .  55 

With  lead  dust 7.79 

With  stone  dust 34.9 

With  stone  workers 4.3 

With  wood  and  paper  dust 5 .  96 

With  tobacco  dust 8 .47 


Pig.  ISO. — A  Vert  Dusty  Trade — Drum  with  Nails  Which  Combs  out  the  Small 
Pieces  of  Broom  Corn.     (Mass.  State  Board  of  Health.) 


Persons  exposed-  to  excessive  amounts  of  dust  for  long  periods  of 
time  suffer  from  a  general  condition  known  as  pneumonokoniosis ;  when 
due  to  coal  dust  the  condition  is  known  as  antJiracosis ;  when  due  to 
stone  dust,  siderosis  or  chalicosis;  when  due  to  vegetable  fibers  such  as 
cotton,  byssinosis.  The  dust  may,  in  part,  be  free  in  the  alveoli  of  the 
lungs  and  in  part  is  inclosed  in  the  cells.     The  epithelial  cells  lining  the 

*  F.  L.  Hoffman,  "Mortality  from  Tuberculosis  in  Dusty  Trades,"  Bull.  79 
and  82,  U.  S.  Bureau  of  Labor. 


1068         HYGIENE  AND  DISEASES  OF  OCCUPATION 

alveoli  act  as  phagocytes.  At  times  sonic  of  tlie  alveoli  may  he  plugged 
with  dust  particles.  Sometimes  the  dust  reuiaJus  in  the  lungs  without 
any  apparent  reaction  on  the  part  of  the  tissues.  Usually  round  cells 
appear  in  the  interalveolar  spaces,  and  other  indications  of  irritation 
and  inflammatory  reaction  take  place,  leading  to  connective  tissue  forma- 
tion between  the  alveoli  and  thickening  of  the  alveolar  wall  itself.  This 
may  progress  to  an  indurative  bronchitis ;  that  is,  several  alveoli  become 
drawn  together  by  the  contracting  connective  tissue  into  a  nodule.  Other 
forms  of  inflammation,  such  as  nodular  peribronchitis  or  nodular  peri- 
vasculitis, may  take  place.  The  dust  particles  are  also  carried  by  the 
phagocytes  to  the  regional  lymphatics,  where  they  lodge.  These  irrita- 
tive processes  cause  a  low  grade  inflammatory  reaction  which  only  awaits 
the  coming  of  bacteria  to  start  specific  or  destructive  processes  (p.  711). 

Some  dust  is  especially  irritating  to  the  conjunctiva,  as  wood  dust 
or  arsenic.  Certain  kinds  of  dust  are  prone  to  cause  chronic  catarrhal 
inflammation  of  the  upper  respiratory  passages,  while  dust  containing 
specific  microorganisms  such  as  anthrax  may  lead  to  acute  pneumonia 
(wool  sorter's  pneumonia). 

General  Principles  of  Prevention. — Much  of  the  dust  raised  in  indus- 
trial processes  may  be  limited  by  improvements  in  machinery  or  pre- 
ventive devices.  Sometimes  the  dust  may  be  kept  down  by  moisture, 
sprays,  or  even  conducting  the  work  under  water  when  practicable.  Thus 
wet  grinding  may  be  substituted  for  dry.  Certain  dusty  operations 
should  be  conducted  in  inclosed  hoods  or  special  cabinets  so  as  to  con- 
fine the  dust  and  thus  protect  the  work  people,  or  the  dust  may  be  re- 
moved by  suction  fan  devices.  Good  ventilation  diminishes  the  danger 
very  much.  When  workmen  are  compelled  to  stay  in  dusty  atmospheres 
they  should  wear  respiratory  masks,  and  the  number  of  persons  thus 
exposed  should  be  reduced  to  a  minimum.  Some  exceedingly  dusty  proc- 
esses, such  as  cleaning  eastings  with  a  sand  blast,  demand  the  wearing 
of  a  protective  headgear.  Many  workmen  prefer  taking  chances  to  wear- 
ing uncomfortable  respirators.  For  a  further  discussion  of  dust,  smoke, 
etc.,  see  Chapter  on  Air. 

THE  TEXTILE  INDUSTRIES 

The  manufacture  of  cotton,  linens,  silk,  and  jute  has  received  an 
unenviable  reputation  as  dangerous  occupations,  despite  the  fact  that 
these  industries  need  not  in  themselves  be  particularly  unhealthy  occupa- 
tions. The  textile  industries  illustrate  several  points  in  the  diseases  of 
occupation.  One  is  that  an  entire  industry  should  not  be  condemned 
becau-ie  one  of  its  processes  is  attended  with  a  certain  amount  of  danger. 
The  other  is  that  the  risks  to  health  may  be  prevented  or  greatly  ameli- 
orated,   General  improvement  in  the  sanitary  conditions  of  textile  mills 


DISEASES  OF  OCCUPATION  1069 

is  one  of  the  promising  signs  of  material  advancement  in  industrial 
hygiene. 

The  principal  conditions  which  affect  health  in  the  textile  industries 
are :  The  working  in  a  dusty  atmosphere  which  is  often  kept  very  moist 
and  usually  very  warm  in  order  to  keep  the  fiber  pliable  and  workable. 
The  humidity  and  temperature  may  be  regulated,  and  by  efficient  systems 
of  ventilation  their  ill  eifects  may  be  minimized  or  even  neutralized. 
The  dust  may  also  be  lessened,  and  in  the  processes  in  which  it  is 
excessive  the  workmen  may  protect  themselves  with  respirators. 

Much  dust  is  raised  during  the  opening  and  emptying  of  the  bales 
of  the  raw  material.  This  is  avoided  in  the  better  mills  by  the  use  of 
machinery.  Most  of  the  dust  is  raised  during  the  process  of  "carding" ; 
some  during  "roving,"  "spinning"  the  yarn,  and  "winding"  it;  and  also 
considerable  during  "weaving."  In  linen  factories  the  "hecklers,"  that 
is,  the  men  who  dress  and  sort  the  rough  flax  (converted  into  tow  by 
having  been  passed  through  a  machine),  are  exposed  to  considerable 
amounts  of  dust  and  sufi^er  from  dryness  of  the  throat  and  bronchitis, 
attended  by  cough  and  shortness  of  breath.  In  the  manufacture  of  sacks, 
twine,  and  carpets  from  jute  the  processes  that  are  extremely  dusty  are 
the  preparing  and  spinning.    The  dvist  given  off  by  jute  is  irritating. 

Humidity  in  Textile  Mills. — Working  in  an  atmosphere  which  is  ex- 
cessively moist  and  frequently  very  warm,  and,  further,  containing  an 
excessive  amount  of  organic  dust,  subjects  the  workmen  to  artificial  and 
unnatural  conditions  which  cannot  be  conducive  to  health.^  Presumably 
the'  heat  and  moisture  predispose  to  rheumatic  states  and  inflammatory 
conditions  of  the  respiratory  tract  which  are  aggravated  by  the  irritation 
of  the  fibrous  dust.  It  is  believed  that  workmen  so  exposed  are  more 
prone  to  contract  common  colds,  bronchitis,  pneumonia,  tuberculosis,  and 
other  inflammatory  diseases  of  the  respiratory  tract. 

The  humidity  of  the  air  is  an  important  factor  in  the  manufacture 
of  textile  fabrics.  The  former  supremacy  of  certain  English  localities 
as  textiles  centers  was  due  to  the  naturally  favorable  climatic  conditions. 
This  led  to  the  adoption  of  artificial  means  of  increasing  the  moisture 
of  the  air  in  mills  less  favorably  located.  When  the  fibers  contain  a  cer- 
tain proportion  of  moisture  they  are  elastic  and  cling  closely  together, 
and  may  be  carded,  combed,  drawn  out,  and  spun  into  yarn,  and  woven 
into  cloth  more  easily  than  when  dry.  When  the  fiber  is  moist  the  work 
in  all  these  processes  runs  better  and  smoother;  finer  grades  of  goods 
may  be  made  from  the  same  stock ;  there  is  less  waste,  and  the  machines 
may  be  run  at  higher  speed  with  less  attention  from  the  operators.  Yarn 
spun  from  dry  fiber  is  harsh  and  kinky ;  it  does  not  retain  its  twist  and 
breaks  easily.  Furthermore,  there  is  more  dust  and  "fly"  which  menace 
the  health  and  comfort  of  the  work  people. 

^  For  effect  of  heat  and  \iumidity  upon  health  see  pages  697  and  744. 


1070         HYGIENE  AND  DISEASES  OF  OCCUPATION 

The  temperature  and  Iniiiiidity  most  siiihiljlc;  for  olitaiiiing  tlie  Ijest 
results  in  each  process  with  material  of  ditrerent  cliaracter  and  quality 
have  been  determined  with  considerable  carC;,  and  generally  speaking 
have  been  found  to  be  such  as  would  not  be  prejudicial  to  health.  Despite 
this  knowledge  excessive  moisture  and  high  temperatures  injurious  Ijotli 
to  health  and  to  the  processes  of  manufacture  are  found  in  some  mills. 

The  necessary  humidity  in  textile  mills  is  obtained  by  a  number  of 
different  devices.  The  methods  which  depend  upon  the  introduction  of 
moisture  directly  into  the  mill  rooms  is  more  objectionable  than  the 
humidification  of  the  air  forced  into  the  rooms  by  some  system  of  me- 
chanical ventilation.  In  any  case,  the  water  used  to  moisten  the  air 
should  be  clean  and  free  from  odor  or  objectionable  impurities. 

The  simplest  method  of  producing  artificial  humidity  in  mill  rooms 
is  by  sprinkling  water  upon  the  floor  and  trusting  to  natural  evapo- 
ration. This  method,  known  as  "degging,"  was  widely  practiced  at  one 
time,  and  is  still  occasionally  found  in  some  foreign  mills.  Degging  was 
replaced  by  shallow  channels  in  the  floor  for  the  water,  or  by  the  placing 
of  pans  of  water  about  the  room,  and  later  by  introducing  steam  directly 
into  the  room.  Steam  is  objectionable  for  the  reason  that  it  unduly  in- 
creases the  temperature.  The  modern  types  of  humidifying  apparatus 
depend  upon  moistening  the  air  by  passing  it  over  water  surfaces  or 
through  water  curtains.  The  spray  moisteners  are  made  in  a  large 
variety  of  patterns.  Some  are  constructed  on  the  principle  of  the  com- 
mon household  atomizer. 

In  Massachusetts  there  is  a  law  regulating  the  amount  of  humidity 
and-  temperature  in  the  textile  mills  which  is  based  upon  the  English 
schedule  contained  in  the  Weaver's  act  of  1870,  The  conditions  in 
Massachusetts,  however,  are  so  different  from  those  found  in  England, 
especially  in  the  summer  time,  that  the  schedule  has  not  been  found 
practical.  Much  of  the  ill  effects  in  the  textile  industries  may  be  neu- 
tralized by  good  ventilation,  abundant  air  space,  cleanliness,  sufficient 
light,  and  the  use  of  improved  machinery.  Special  rooms  should  be 
provided  for  the  clothes,  in  order  that  the  moist  garments  may  be 
changed  for  dry  ones  before  the  work  people  go  into  the  open  air,  thus 
avoiding  the  chilling  effects  of  damp  garments. 

WOOD  DUST 

It  is  well  known  that  workers  in  wood  are  subject  to  the  mechanical 
effects  of  ordinary  sawdust,  which  is  moderately  irritating.  Workers 
with  boxwood,  teak,  and  sequoia  (redwood)  are  subject  also  to  the  gen- 
eral poisonous  effects  of  alkaloids  and  other  substances  contained  in 
these  woods  which  may  have  more  marked  general  effects,  especially  on 
the  circulation  and.   still  more  frequently,  marked  local  effect  on  the 


DISEASES  OF  OCCUPATIOI^  1071 

mucous  membranes  and  the  skin.  In  1902  Young  observed  that  men 
working  with  Maracaibo  boxwood  complained  of  dryness  of  the  throat 
and  inflammation  of  the  eyes  which  lasted  two  or  three  days.  This 
wood  is  used  in  the  making  of  rulers.  Oliver  notes  that  joiners  that 
saw  and  chip  sequoia  wood  suffer  with  symptoms  resembling  a  bad  cold 
in  the  head  and  chest;  a  tolerance  seems  to  be  established  except  by 
men  who  are  liable  to  bronchitis  and  asthma.  Woimds  caused  by  splin- 
ters of  the  wood  invariably  suppurate  and  do  not  heal  readily.  Oliver 
found  that  rats  were  also  susceptible  to  sequoia  sawdust.  They  suffer 
from  a  running  at  the  nostrils. 

Certain  kinds  of  wood  have  a  bad  reiDutation  among  joiners.  Some 
sawdusts  are  more  irritating  than  others,  probably  from  the  large  amount 
of  inorganic  matter  they  contain.  A  West  African  boxwood  from  which 
shuttles  are  made  causes  headache,  coryza,  excessive  secretion  of  tears, 
and  attacks  of  asthma.  These  woods  contain  alkaloids,  glucosids,  and 
other  extractives.  Workers  in  teakwood  occasionally  suffer  from  der- 
matitis. 

MINING 

Coal  mining  is  one  of  the  dangerous  and  unhealthy  occupations. 
The  dust,  the  unnatural  conditions  under  which  the  miner  is  com- 
pelled to  work  underground,  the  poor  air,  and  sometimes  exposure  to 
poisonous  fumes  all  conspire  to  make  this  occupation  one  attended  with 
unusual  risks.  The  unsatisfactory  methods  for  disposal  of  feces  often 
found  in  mines  favor  the  spread  of  hookworm  and  other  parasites.  To 
this  must  be  added  the  danger  of  accidents  and  explosions. 

The  conditions  of  mines  have  been  greatly  improved,  especially 
through  better  systems  of  ventilation,  through  the  use  of  safety  lamps, 
through  reduction  of  the  amount  of  dust,  the  regulation  of  the  hours 
of  occupation,  and  devices  to  detect  poisonous  and  explosive  gases.  The 
sanitation  and  cleanliness  of  mines  have  also  shown  development.  As 
an  illustration  of  some  of  the  complications  and  difficulties  of  this  sub- 
ject, reference  is  made  to  the  fact  that  moisture  will  prevent  explosion 
in  mines.  Moisture  was,  therefore,  introduced  into  some  of  the  German 
mines  with  good  results,  so  far  as  explosions  are  concerned,  but  the 
moisture  favored  the  development  of  the  hookworm  larvae  and  hence 
caused  such  a  great  increase  in  the  amount  of  hookworm  infection  that 
it  became  necessary  to  seek  other  methods. 

The  mortality  from  accidents  and  diseases  of  the  lungs  is  high.  Coal 
miners'  phthisis,  or  anthracosis,  is  a  well-known  disease.  Although  coal 
is  a  vegetable  product  the  result  largely  of  microbial  action,  fresh  coal 
is  free  from  microorganisms.  Oliver  points  out  that  in  some  of  the  min- 
ing centers  colliers  not  only  suffer  less  from  pulmonary  tuberculosis  than 
persons  in  other  occupations,  but  that  they  also  suffer  unequally  in  dif- 


1073         HYdlENE  AA'I)  DISEASES  OF  OCCUPATlUxN" 

ferent  mining  centers.  Why  this  is  so  it  is  clillieiilt  to  say.  Wliiie  tlie 
death  rate  from  pulmonary  tuberculosis  in  miners  is  in  some  places  low, 
that  due  to  non-tuberculous  aiTections  of  the  lungs  is,  comparatively 
speaking,  high. 

DeCrocq  speaks  of  the  rarity  of  phthisis  among  Belgian  coal  miners. 
Arnold  reports  that  in  Germany  tu,berculous  diseases  are  rare  among  coal 
miners  and  that  there  is  a  prevailing  opinion  that  anthracosis  is  antago- 
nistic to  tuberculosis,  Goldman  attributed  the  freedom  of  the  coal  miner 
from  pulmonary  tuberculosis  to  an  antiseptic  action  of  the  coal  dust. 

Other  diseases  to  which  coal  miners  are  subject  are  "beat  hand,"  as  a 
consequence  of  using  the  pick  and  friction  of  the  handle.  The  skin 
of  the  palm  over  the  bases  of  the  fingers  of  both  hands,  also  the  skin 
over  the  fleshy  ball  of  the  thumb  and  that  of  the  other  side  of  the  hand, 
becomes  extremely  hard  and  horny.  In  addition  to  the  enormous  thicken- 
ing of  the  epithelial  layers  of  the  skin  there  is  inflammation  of  the  subcu- 
taneous connective  tissue.  Occasionally  suppuration  takes  place  in  the 
deeper  layers  of  the  hard  skin.  The  suppuratory  areas  are  called  "keens" 
by  the  miners.  Beat  hand  is  a  painful  affection  and  unfits  the  individual 
for  work  for  some  time.  A  similar  condition  sometimes  occurs  on  the 
knees  and  elbows,  hence  the  term  "beat-knee"  and  "beat-elbow."  Miners 
also  frequently  complain  of  backache,  largely  the  result  of  the  peculiar 
mode  of  sitting  while  at  work.  Dyspepsia,  miner's  nystagmus,  and  anky- 
lostomiasis are  other  conditions  to  which  miners  are  prone. 

Cancer. — Chronic  irritation  produced  by  coal  and  petroleum  products 
acts  as  a  chemical  irritant  in  the  production  of  cancer,  accounting  for 
chimney-sweep's  cancer  and  the  tendency  to  cancer  among  workers  in 
tar  and  paraffin,  anilin,  tobacco,  and  soot.     (See  also  page  504.) 

EFFECTS  OF  HEAT 

In  many  trades  workmen,  more  particularly  firemen,  stokers,  workers 
in  foundries  and  steel  mills,  are  exposed  to  high  degrees  of  heat.  Ed- 
sall  ^  has  recently  called  attention  to  the  ill  effects  of  exposure  to  unusual 
degrees  of  heat.  The  symptoms  are  acute,  violent  muscle  spasms.  The 
acute  effect  may  be  heat-stroke  and  heat  prostration;  there  may  be 
nervous  lesions  such  as  focal  meningitis,  as  well  as  more  or  less  serious 
circulatory  weakness,  anemia,  acute  and  chronic  disturbances  of  diges- 
tion, acute  and  chronic  nephritis.  Eespiratory  diseases  and  skin  lesions 
appear  to  be  unduly  frequent  in  persons  exposed  to  high  degrees  of  heat. 
There  is  more  than  a  suspicion  that  cataracts,  retinal  and  choroidal 
changes,  or  chronic  conjunctival  lesions  are  brought  on  in  glass-blowers 
and  perhaps  also  in  iron  puddlers  and  other  persons  whose  eyes  are  ex- 
posed to  very  intense  heat  and  light.     De  Schweinitz  states  that  he  can 

^Jour.  Amer,  Med.  Assn.,  LT,  T><?q.  5,   3  908,  p.   1969. 


DISEASES  OF  OCCUPATION  1073 

often  tell  whether  men  working  at  puddling  furnaces  are  right-handed 
or  left-handed  by  studying  the  effects  of  this  exposure  on  their  eye 
grounds.  Eopke  ^  states  that  Quint  described  to  him  cases  of  right-sided 
cataract  in  right-handed  iron  workers  and  left-sided  in  those  who  were 
left-handed. 

Unnecessary  Noise. — Unnecessary  noise  may  become  a  nuisance,  and 
under  certain  conditions  is  a  menace  to  health,  especially  high-pitched 
sounds  long  continued,  which  lead  to  deafness;  hence  the  deafness  of 
boiler  makers  and  others  is  a  true  occupational  disease.  Sieberman  and 
others  have  demonstrated  that  long-continued  exposure  to  high-pitched 
sounds  causes  degenerative  changes  in  the  organ  of  Corti  in  the  internal 
ear. 

Noises  also  disturb  rest  and  sleep,  irritate  the  nervous  organism,  and 
induce  unpleasant  results.  The  susceptibility  to  noises  varies  greatly. 
Many  unnecessary  noises  can  be  stopped  in  shop  and  street  with  a  corre- 
sponding saving  of  energy  and  increase  of  efficiency.  It  is  now  realized 
that  unnecessary  noise  represents  misspent  energy,  and  hence  so  much 
avoidable  waste.  Quiet  zones  at  least  should  be  established  around 
schools,  hospitals,  churches,  courts,  lecture  and  music  halls,  etc. 

Lighting — see  pages  706  and  1093. 

COMMUNICABLE  INFECTIONS 

There  are  several  infections  to  which  workmen  in  certain  industries 
are  specially  subjected.  Of  these  the  best  known  are :  anthrax,  or  wool- 
sorter's  disease  from  hides  and  hair;  and  hookworm  disease,  or  miner's 
anemia,  from  polluted  soil.  Also  glanders  from  horses.  Tuberculosis 
sometimes  results  directly,  but  more  often  indirectly,  from  occupation. 

Wool-sorter's  disease  is  an  infection  with  the  Bacillus  anthracis.  The 
spores  cling  to  the  hides  of  animals  that  have  died  from  the  disease 
or  have  been  slaughtered  on  account  of  it.  Spores  also  remain  attached 
to  wool  and  horsehair  and  to  pig's  bristles  used  in  brush-making.  The 
infection  may  be  taken  in  through  the  slightest  scratch  or  any  open 
wound  or  through  inhalation  of  dust  containing  the  spores,  or  may  be 
ingested  in  the  food.  Wool-sorter's  disease  most  often  appears  in  the 
wool-sorting,  wool-combing,  and  spinning  industries,  in  the  manipula- 
tion of  horsehair  for  stuffing  chairs  and  mattresses,  and  the  prepara- 
tion of  bristles  for  brush-making.  Anthrax  has  also  been  met  with  in  per- 
sons employed  in  tanyards  and  in  warehouses  that  connect  with  docks. 
The  subject  is  fully  discussed  by  Legge  in  his  Milroy  lectures.^ 

The  prevention  of  anthrax  is  first  and  foremost  a  problem  in  animal 
husbandry  which,  in  this  country,  comes  under  the  purview  of  the  Bureau 

^Weyl's  "Handbuch    der   Arboitprkrankheiten,"    1908. 
''Lancet,  March    18,   inOf). 


1074         HYGIENE  AND  DISEASES  OF  OCCUPATIOX 

of  Animal  Industry.  Animals  having  anthrax  sliould  !)(■  kilJcd  and  all 
anthrax  carcasses  should  be  buried,  incinerated,  or  tajiked  in  such  a 
manner  as  to  destroy  the  infection  and  prevent  its  dissemination.  This 
is  one  of  the  questions  for  international  sanitary  agreement,  for  the  wool 
from  Prussia,  the  hair  and  mohair  from  Asiatic  Turkey,  the  horse- 
hair from  China,  the  bristles  from  Siberia,  and  the  hides  from  India 
may  carry  the  anthrax  spores  from  these  far-off  lands  and  cause  in- 
fection among  our  workmen.  It  is  exceedingly  difficult  to  disinfect 
hides  so  as  to  kill  the  anthrax  spores.  In  fact  it  is  practically  impossible 
to  kill  anthrax  spores  without  damaging  the  hides  for  commercial  use. 
The  U.  S.  Bureau  of  Animal  Industry  recommends  the  following  meth- 
ods for  the  disinfection  of  hides :  ^ 

Each  skin  or  hide  shall  be  immersed  for  not  less  than  five  minutes  in 
a  5  per  cent,  solution  of  liquor  cresolis  conipositus,  or  a  5  per  cent,  solu- 
tion of  carbolic  acid,  for  not  less  than  four  hours  in  a  mixture  composed 
of  one  part  of  bichlorid  of  mercury  to  a  thousand  parts  of  salt  solution 
containing  not  less  than  15  per  cent,  of  sodium  chlorid. 

Horsehair,  cowhair,  goat's  hair,  pig's  bristles,  and  wool  before  they 
are  manipulated  should  be  disinfected  either:  (1)  by  steam  at  17  pounds 
pressure,  equivalent  to  220°  P.,  for  at  least  an  hour;  (2)  by  boiling  for 
at  least  a  quarter  of  an  hour  in  a  2  per  cent,  solution  of  potassium  per- 
manganate, and  subsequent  bleaching  in  a  3  to  4  per  cent,  solution  of 
sulphurous  acid;  (3)  by  boiling  in  water  for  at  least  two  hours.  In 
Germany  the  government  regulations  require  the  disinfection  of  wool 
and  hair  from  foreign  parts  and  provide  public  disinfection  stations  for 
this  purpose.     For  a  discussion  of  anthrax  see  page  315. 

Glanders,  see  page  310. 

Hookworm  Disease. — Miners  are  specially  subject  to  hookworm  dis- 
ease. The  parasite  enters  through  the  skin  from  the  polluted  soil  of 
the  mines.  The  outbreak  which  called  attention  to  this  danger  was 
the  epidemic  which  occurred  among  the  workmen  on  St.  Gothard's 
tunnel  in  1892.  Since  then  the  disease  has  been  called  "miner's  ane- 
mia." Gunn  ^  found  that  from  50  to  80  per  cent,  of  those  working  in 
the  mines  of  California  and  the  neighboring  state  of  Nevada  were  in- 
fected with  hookworms.  For  a  full  discussion  of  hookworm  disease  see 
page  125. 

Tuberculosis. — Tuberculosis  is  often  spoken  of  as  the  most  important 
disease  of  occupation.  There  is  no  doubt  that  it  is  the  most  important 
single  problem  in  industrial  hygiene,  but  whether  it  is  commonly  con- 
tracted as  a  result  of  occupation  is  a  question.  It  is  certain  that  dusty 
trades,  poorly  ventilated  workrooms,  sedentary  occupation,  fatigue,  irri- 

^  U.   S.   Dept.    of   Agriculture,   Bureau    of   Animal   Industry,   Amendment  to 
Regulation   10,  section  8,  paragraph  3,  Nov.  20,   1915. 
V.  A.  M.  A.,  .Jan.  28,  1911,  Vol.  LVI,  No.  4,  p.  259. 


DISEASES  OF  OCCITPATION  1075 

tating  fumes,  long  hours  and  the  grind  of  routine,  as  Avell  as  other  fac- 
tors found  in  industries,  predispose  to  the  disease. 

The  view  generally  accepted  now  is  that  the  infection  is  usually  con- 
tracted in  infancy  or  early  childhood,  hut  manifests  itself  clinically  later 
in  life.  The  problem  of  tuberculosis  is  intimately  hound  up  with  per- 
sonal habits  and  home  life.  Therefore,  it  is  quite  as  proper  to  consider 
it  a  house  disease  as  an  occupational  disease.  Bad  sanitary  and  hygienic 
conditions  light  up  latent  infections,  and  it  is  hopeless  to  expect  arrest 
or  cure  of  the  process  so  long  as  the  victim  continues  to  Avork  under 
unfavorable  conditions.  The  problem  of  what  to  do  for  the  tuberculous 
workman  and  his  family;  with  the  "cured"  and  arrested  cases;  as  well 
as  to  find  suitable  occupation  for  the  pretubercular  types,  is  often  a  diffi- 
cult puzzle  for  the  social  worker. 

Statistics  plainly  show  that  tuberculosis,  as  well  as  bronchitis,  em- 
pyema, and  other  diseases  of  the  respiratory  tract,  is  unusually  prevalent 
among  grinders,  engravers,  compositors,  stone  workers,  millers,  bakers, 
plasterers,  brass  workers,  glass  cutters,  furriers,  weavers,  and  other  trades 
in  which  there  is  undue  exposure  to  dust  and  irritating  vapors. 

The  subject  of  tuberculosis  is  discussed  in  full  on  page  134. 

Other  occupations  in  which  there  is  a  special  exposure  to  the  risk 
of  infection  are:  physicians,  nurses,  v/ard-tenders,  pathologists,  experi- 
mental investigators,  etc. 

TEE  CAISSON  DISEASE 

The  effects  of  compressed  air  and  the  effects  of  rarefied,  air  are  dis- 
cussed on  pages  681  and  684. 

REFERENCES 

Oliver,  Thomas  :  "Diseases  of  Occupation,  from  the  Legislative,  Social, 
and  Medical  Points  of  View."    New  York,  1909. 

Weyl,  Theodor:  "Handbuch  der  Hygiene."  Gewerbehyg.,  Vol.  VIII, 
Jena,  1897. 

Various  authors :  "Risks  in  Modern  Industry."  Published  by  the 
American  Academy  of  Political  and  Social  Science,  Phila.,  Pa.,  1912. 

Goldmark,  Josephine,  and  Brandeis,  L.  D. :  "Fatigue  and  Efficiency." 
Charities  Publication  Committee,  105  E.  22d  St.,  New  York,  1912. 

Rambousek,  J. :     "Industrial  Poisoning."     Arnold,  London. 

Kober,  G.  M.,  and  Hanson,  W.  C. :  "Diseases  of  Occupation  and  Voca- 
tional Hygiene."     P.  Blakiston's  Son  and  Co.,  Philadelphia,  1916. 

Bulletins  of  the  U.  S.  Bureau  of  Mines  and  the  U.  S.  Labor  Bureau. 

Thompson,  W.  G. :     "The  Occupational  Diseases."     D.  Appleton  &  Co. 

Price,  G.  M. :     "The  Modern  Factory."     1914. 


SECTION  XI 
SCHOOLS 

It  took  a  long  time  to  realize  that  the  whole  child  goes  to  school — 
his  body,  mind,  and  soul;  that  education  of  the  mind  alone  is  one- 
sided and  may  be  hurtful ;  finally,  that  the  hygiene  of  the  child  and  his 
teacher,  as  well  as  the  sanitation  of  school  buildings  and  their  equip- 
ment, is  of  fundamental  importance.  The  combination  of  compulsory 
education  and  schools,  having  an  unbalanced  curriculum  or  impure 
water  or  vitiated  air  or  improper  sanitation,  is  nothing  short  of  a  crime 
by  the  state  against  the  state.  The  child  profits  directly  from  attendance 
upon  a  school  which  has  due  regard  for  the  child's  physical  well  being 
and  the  development  of  his  character;  the  state  profits  indirectly  from 
the  lessons  in  sanitation  and  hygiene  which  are  carried  into  the  child's 
home,  and  are  applied  as  a  matter  of  course  in  the  home  of  the  future 
citizen.  Thus  the  principles  of  personal  hygiene  and  sanitation  become 
second  nature,  and  in  this  way  the  conquest  of  the  preventable  diseases 
may  be  materially  hastened.  It  is  an  economic  waste  to  educate  children 
and  then  permit  them  to  die  of  some  preventable  infection  before  they 
have  reached  the  period  of  maturity  and  productivity. 

The  school  furnishes  abundant  material  for  the  physiologist  and  the 
psychologist  to  study  growth  and  development.  The  effect  of  the  nature 
and  order  of  the  studies  for  each  school  year ;  the  hours  of  work,  rest, 
and  play;  the  direction  of  physical  exercise  should  all  be  regulated  ac- 
cording to  the  average  requirements  and  capacities  of  each  school  period, 
and  should  be  based  upon  accurate  observations  extending  over  long 
periods  of  time.  Both  the  immediate  effects  and  the  remote  influences 
upon  adult  life  should  be  taken  into  consideration.  Youth  is  the  time 
of  unrest  and  activity,  and  it  is  part  of  the  school  work  to  direct  these 
energies  so  as  to  obtain  the  best  development ;  youth  also  requires  gener- 
ous nourishment  and  sufficient  sleep.  A  child  who  comes  to  school  tired 
and  worn  from  disturbed  slumber  cannot  profit  in  body  or  mind.  The 
child  who  comes  to  school  hungry  or  who  does  not  have  a  judicious  lunch- 
eon at  the  recess  period  is  seriously  handicapped  physically  and  mentally. 
The  quality  of  the  food  offered  for  sale  at  recess  should  be  under  close 
scrutiny.  The  hot  lunches  and  nutritious  food  furnished  some  of  the 
school  children  in  Boston  and  other  cities  at  a  reasonable  price  is  a  prac- 
tical and  wise  movement. 

One  of  the  duties  of  the  school  is  to  teach  and  to  require  at  all 

1077 


1078  SCHOOLS 

times  cleanliness  of  person  and  vlotluii'^.  The  example  of  clean  school- 
rooms, corridors,  lockers,  toilets,  basement,  and  grounds  will,  in  time, 
influence  the  young  citizen.  Floors  especially  should  be  kept  clean  and 
the  child  be  required  to  use  the  door  mats  before  entering  the  building. 
Dust  must  be  discouraged  in  all  ways.  In  some  schools  in  poor  districts 
it  is  a  good  plan  to  have  shower  baths  for  those  pupils  who  do  not 
enjoy  good  bathing  facilities  at  home.  A  toothbrush  drill  is  the  means 
of  teaching  many  a  child  the  first  principles  in  dental  prophylaxis.  The 
teacher  should  be  constantly  on  the  lookout  to  impress  upon  the  pupils 
the  elementary  facts  in  hygiene,  such  as  turning  aside  the  head  and 
holding  the  handkerchief  before  the  mouth  and  nose  when  coughing  or 
sneezing.  The  teacher  should  discourage  the  habit  children  have  of 
carrying  their  fingers  to  their  mouths  and  noses.  The  anti-spitting  rules 
should  be  reiterated  and  strictly  enforced.  The  danger  of  mouthing 
toys  and  pencils  and  the  habit  generally  of  placing  things  in  the  mouth 
should  be  discouraged;  "swapping"  partly  eaten  articles  of  food  should 
be  prohibited,  and  the  reasons  explained.  Cleanliness  is  not  instinctive 
in  children;  it  must  be  learned.  The  significance  of  modern  biological 
cleanliness  can  come  only  through  education  and  example.  Progress 
in  these  matters  cannot  be  made  without  an  intelligent  understanding 
on  the  part  of  the  teacher.  It  is  therefore  important  to  teach  the 
teacher. 

Fatigue,  prolonged  and  oft  repeated,  may  injure  the  development 
and  health  of  the  child.  Fatigue  is  favored  by  poor  ventilation,  com- 
pulsory sitting  upon  hard  and  ill  fitting  seats  at  improperly  constructed 
desks,  prolonged  tension  of  a  strict  discipline,  studies  that  are  too  in- 
tensive, and  insufficient  relaxation  or  inconsiderate  treatment  of  the 
little  ones.  Discipline,  obedience,  and  regard  for  the  human  rights  of 
others  are  among  the  most  important  things  learned  at  school. 

Many  a  child  is  unjustly  disciplined  and  his  little  soul  harassed 
through  no  fault  of  his  own,  but  perhaps  on  account  of  defective  eye- 
sight or  hearing,  or  other  physical  handicap,  or  due  to  some  mental 
deficiency. 

The  question  of  home  work  should  be  carefully  regulated  in  accord- 
ance with  the  capacity  and  age  of  the  child.  Children  should  not  be 
kept  busy  at  prescribed  work  most  of  the  hours  of  the  day.  Some  time 
should  be  left  for  quiet  play  and  the  encouragement  of  personal  inclina- 
tions during  which  time  the  best  development  unconsciously  occurs. 
Initiative,  self-reliance,  and  self-help  are  submerged  by  lack  of  free  time. 
The  amount  and  nature  of  the  work,  both  in  and  out  of  school,  must  be 
judiciously  considered  and  should  be  based  upon  long  years  of  careful 
study  and  observation.  The  immediate  as  well  as  the  remote  effects 
should  be  taken  into  consideration.  Many  an  ill-tempered  child  is  simply 
overwrought  and  chronically  tired  out  through  excessive  application  of  a 


SCHOOLS  1079 

conscientious  and  studious  nature  to  tasks  beyond  the  physiological  ca- 
pacity of  his  little  brain  and  body. 

The  child  should  not  be  sent  to  school  too  young.  Children  must 
first  learn  to  walk,  run,  talk,  and  coordinate  muscles  before  they  under- 
take reading,  writing,  and  arithmetic.  Pupils  should  not  be  graded  ac- 
cording to  their  ages,  but  according  to  their  capacity  and  physical  de- 
velopment.    Individual  aptitudes  should  be  encouraged. 

For  the  elementary  schools  one  short  morning  session  is  enough,  but 
city  circumstances  often  demand  two  sessions.  The  general  tendency  is 
to  reduce  the  hours  of  compulsory  school  attendance  and  increase  the 
optional  time  through  elective  systems  which  encourage  and  foster  native 
talents. 

Primary  pupils  should  not  spend  more  than  one-third  of  their  school 
time  in  their  seats.  Exercises  of  various  kinds  that  call  into  play  mus- 
cular activity  are  most  important  at  this  age,  not  only  for  mental 
growth,  but  for  physical  growth,  as  well  as  for  relief  from  the  fatigue 
occasioned  by  sitting  at  desks. 

The  child  on  beginning. school  life  enters  an  environment  radically 
different  from  the  free  and  active  life  which  was  his  before  school  days 
began.  The  effect  may  be  seen  by  the  fact  that  children  usually  lose 
weight  and  the  nervous  system  becomes  affected  during  the  first  weeks 
of  school. 

Ungraded  or  special  schools  should  be  provided  for  backward  and 
defective  children  and  for  those  having  favus,  ring-worm,  rachitis,  or 
other  conditions  requiring  either  special  pedagogical  methods  or  particu- 
lar medical  treatment.  Open-air,  or  fresh-air,  schools  for  children  who 
have  or  are  threatened  with  tuberculosis  serve  a  very  useful  purpose. 

Finally,  the  whole  school  program  should  remember  that  the  object 
is  not  to  teach  the  child  to  be  a  child,  but  to  direct  his  development  so 
as  to  become  a  useful  man  or  woman.  The  school  system  should  there- 
fore be  carried  out  with  due  regard  for  future  events  and  should  be 
correlated  with  the  adult  life  of  the  child. 

School  Building. — The  school  must  be  centrally  located,  so  as  to  be 
convenient  especially  for  the  primary  and  grammar  grades,  and  the 
school  building  should  be  modern,  artistic,  clean,  and  sanitary  in  all  its 
appointments.  Every  school  building  should  have  playgrounds  con- 
nected with  it.  Playgrounds  should  be  level  and  located  on  the  sunny 
side  of  buildings;  about  30  square  feet  for  each  pupil  is  necessary  to 
meet  the  demands  of  play.  Thus  1,000  pupils  require  300  x  100  square 
feet  for  playgrounds  alone.  In  cities,  roofs  may  be  utilized  for  play. 
A  limited  play  area  is  best  utilized  by  organizing  recess  play  by  sex  and 
grades.  School-houses  should  be  built  in  places  that  are  quiet  and 
free  from  traffic  and  nuisances,  dangers  of  various  kinds,  and  on  ground 
that  is  either  naturally  dry  or  made  so  by  subsoil  drainage.     The  build- 


1080  SCHOOLS 

iug'  slioiild  ])e  solidly  constructed  and  sliotdd  stand  apart,  so  that  sun 
and  air  may  reach  it  from  all  sides.  A  substantial  and  artistic  structure 
well  placed  has  an  important  influence  upon  the  young  mind  and 
character.  Trees  and  judicious  landscape  gardening  should  provide  shel- 
ter and  shade  and  add  to  the  attractiveness.  The  foliage,  however,  must 
not  interfere  with  the  light  and  ventilation  of  the  school-rooms.  If  the 
building  faces  north,  with  corridors  and  stairs  on  this  side,  all  the  rooms 
will  have  sunlight  at  some  time  during  the  day.  The  best  general  ar- 
rangement of  the  plan  of  the  building  is  that  in  which  the  school-rooms 
are  all  placed  on  one  side  of  the  building,  with  the  corridors,  halls,  stair- 
ways, and  wardrobes  on  the  other.  Built  in  the  old  way,  with  rooms 
around  a  central  well,  school-houses  have  dark  central  halls  and  stair- 
cases, and  favorable  lighting  cannot  be  had  in  some  of  the  school- 
rooms. 

Buildings  three  or  four  stories  high  in  schools  which  require  the 
pupils  to  pass  from  the  lower  to  the  upper  floors  several  times  a  day  im- 
pose a  stress  in  climbing  so  many  flights  of  stairs  that  may  be  injurious 
to  the  pupils,  especially  to  girls.  Such  buildings  may  be  provided  with 
elevators,  or  at  least  with  inclines  instead  of  stairs.. 

The  basement  should  be  under  the  whole  building  and  carefully  pro- 
tected against  dampness.  Further,  the  basement  should  be  well  lighted, 
sunny,  and  above  the  grade. 

School  buildings  should  have  at  least  two  entrances,  with  doors 
opening  outward;  the  halls  and  corridors  should  be  generous  and  well 
lighted,  and  the  stairs  have  easy  risers  and  treads  for  children.  The 
risers  should  be  about  6  inches  and  the  treads  no  greater  than  12  inches. 

The  School-room. — The  school-room  is  the  unit  in  planning  a  school 
building;  that  is,  the  building  should  be  a  number  of  school-rooms 
properly  disposed,  and  not  a  building  cut  into  school-rooms  whose  size 
and  arrangements  are  dependent  upon  the  size  and  shape  of  the  build- 
ing. 

Some  of  the  important  considerations  in  the  school-room  are  the 
number  of  pupils  to  be  accommodated,  its  size  and  shape,  the  amount 
and  direction  of  the  light,  the  ventilation  and  heating. 

The  minimum  floor  space  for  each  pupil  should  be  15  square  feet. 
If  18  square  feet  are  allowed  all  exercises  are  made  easier  both  for 
pupil  and  teacher.  Two  hundred  cubic  feet  of  air  space  is  the  minimum 
commonly  allowed ;  therefore  a  standard  school-room  designed  to  accom- 
modate 30  pupils  should  be  20  feet  wide  by  24  feet  long,  with  a  ceiling 
13  feet  high.  The  best  shape  for  a  school-room  is  that  of  an  oblong, 
the  width  being  to  the  length  about  as  3  to  4.  No  teacher  should  be  re- 
quired to  have  classes  exceeding  30  pupils.  The  rooms,  floor  space,  and 
air  space  should  be  at  least  as  capacious  for  the  primary  as  for  the  gram- 
mar grades.  . 


SCHOOLS  1081 

BOSTON  STANDARD ELEMENTARY  GRADES. 

Size:     20  feet  by  28  feet  for  elementary  grades. 

20  feet  by  30  feet  for  upper  elementary  grades. 

12  feet  high  in  clear. 
About  ten  or  twenty  per  cent,  of  rooms  should  be  of  a  size  to  seat 
fifty  pupils. 

KINDERGARTEN 

800  to  900  sq.  ft.  and  capable  of  having  a  circle  16  feet  in  diameter 
painted  on  floor  with  at  least  4  ft.  all  around  it. 

HIGH  SCHOOL 

26  ft.  by  32  ft.  for  42  pupils. 

33  ft.  8  in.  by  43  ft.  for  60  to  80  pupils. 

16  ft.  by  26  ft.  for  recitation  rooms. 

3,750  to  4,000  sq.  ft.  with  a  height  of  not  less  than  24  ft.  for  high 
school  gymnasium. 

The  color  of  the  walls  should  be  such  as  to  absorb  the  least  light  and 
prove  least  taxing  to  the  eyes.  A  light  green-gray  is  favored  for  the 
walls,  and  white  or  cream  for  ceilings.  The  surface  should  not  be  glossy 
and  should  either  be  coated  with  an  oil  paint,  so  that  the  walls  may  be 
washed,  or,  better,  calcimined  with  a  water  paint  that  may  be  readily 
renewed.    The  ceiling  should  be  white,  so  as  to  reflect  the  light. 

The  School  Furniture. — The  most  important  articles  of  school  furni- 
ture, considered  from  the  view  of  hygiene,  are  desks  and  desk  chairs, 
for  the  reason  that  the  pupil  spends  during  school  hours  so  much  time  at 
work  at  his  desk.  Unless,  therefore,  desks  and  chairs  are  constructed 
with  full  regard  for  certain  well-known  laws  of  hygiene  they  produce 
defects  of  eyesight,  injurious  effects  as  to  posture,  and  wrong  habits  of 
carriage  which  are  borne  through  life  and,  sadly  enough,  become  more 
pronounced  as  the  years  increase.^ 

Professor  Bowditch  ^  of  Harvard  University  carefully  measured  and 
weighed  25,000  school  boys  and  girls  of  Boston  and  found  surprising 
variations.  Taking  ages  on  their  last  birthdays  Professor  Bowditch 
found  the  variations  in  height,  indicated  in  table,  p.  1082. 

Besides  the  variations  in  height  there  is  also  variation  in  growth,  and 
provision  for  this  difference  must  therefore  be  made  in  the  construction 
and  adjustment  of  the  desk  and  seat.  The  growth  of  girls  is  more 
rapid  from  12  to  14  years  of  age,  while  boys  grow  most  rapidly  from 
14  to  16  years  of  age.  The  annual  growth  during  the  maximum  period 
is  often  an  inch  more  than  the  annual  growth  at  other  periods.     Fur- 

^Shaw,  Edward  R.:  "School  Hygiene."     The  Macmillan  Co.,  N.  Y.,  1902. 
^Twenty-second    Annual    Report,    State    Board    of    Health    of    Mass.,    1890, 
pp.  479-522. 


1082 


SCPIOOLS 

Variations  in  Height  of  Boys  and  Girls 


6  years  of  age. 
Difference . . 


Boys 


47.131 

40.66 


6.47 


Girls 


47.36 
40.57 


6.79 


11  years  of  age. 
Difference. . . 


57.50 
49.47 


57.96 
49.33 


8.03 


8.63 


15  years  of  age. 
Difference. . . 


67.90 
56.55 


65.00 
57.39 


11.35 


7.61 


'  All  figures  are  inches 


ther,  there  exist  certain  anatomical  differences  of  proportion  between 
boys  and  girls.  The  sitting  height  of  girls  is  greater  proportionately 
than  their  standing  height  in  comparison  with  boys. 


Fig.  151. — Faulty  Posture.     (Shaw's  "School- Hygiene,"  Macmillan  Co.) 

TfiE  Desk  and  Seat. — Tbe  desk  and  seat  must  therefore  be  ad- 
justed so  as  to  provide  for  differences  of  height  and  differences  of  growth. 
The  desk  must  not  be  a  prison  stall,  but  should  be  comfortable  and 
roomy.     It  must  not  favor  the  development  of  myopia  and  must  not 


SCHOOLS  1083 


force  a  pupil  into  wrong  postures.     The  matter  is  of  greater  importance 
than  school  men  generally  recognize. 

The  chair  and  seat  should  be  of  such  a  height  that  the  thigh  of  the 
pupil  when  seated  will  be  perfectly  level,  the  lower  leg  being  in  an 
exactly  vertical  position,  with  tlic   foot  resting  wholly  upon  the  floor; 


Fig.  152. — The  Hetjsinger  Desk.     (Shaw's  "School  Hygiene,"  Macmillan  Co.) 

that  is,  the  thigh  and  the  lower  leg  will,  when  the  chair  is  of  a  proper 
height,  form  a  right  angle  with  each  other.  The  seat  must  therefore 
be  adjusted  accordingly.  The  seat  itself  should  not  be  flat,  but  somewhat 
concave,  the  lowest  part  of  the  concavity  being  where  the  tuberosities 
of  the  ischium  rest.  The  concavity  has  the  additional  advantage  of 
counteracting  the  tendency  to  slide  forward  on  the  seat  when  the 
pupil  leans  back.  The  seat  should  have  a  back  rest  that  will  support 
the  small  of  the  back  properly  without  leaning  back  excessively.   Whether 


1084 


SCTiOOLS 


01'  not  il  supports  the  reist  of  tlic  hack  is  of  small  (;onsoqrionco.  Siipporl. 
of  the  back  carried  to  the  level  of  ilic  shoulder  bhides  is  likely  to  do 
more  harm  than  good. 

The  distance  between  the  seat  and  the  desk  should  be  such  that  the 
scholar  may  read  at  the  desk  and  write  on  it  without  leaning  forward 
more  than  a  little  and  without  entirely  losing  the  support  of  the  back 
rest.  The  desk  should  not  be  so  close  as  to  press  against  the  abdomen, 
nor  near  enough  to  interfere  with  easy  rising  from  the  seat.  This 
means  a  distance  of  10i/>  to  141/2  inches  from  the  edge  of  the  desk  to 
the  seat  back.     It  also  means  that  the  seat  must  not  project  under  the 

desk  more  than  an  inch  at  most. 
The  desk  should  be  high  enough  for 
the  arm  to  rest  comfortably  without 
much  resting  of  the  elbow ;  not,  how- 
ever, so  low  that  the  scholar  must 
bend  down  to  write  on  it. 

If  the  desk  top  is  made  to  slide 
backward  and  forward  it  will  give 
the  pupil  more  freedom  of  movement 
while  at  the  desk  and  will  also  per- 
mit him  to  sit  down  at  the  desk 
and  rise  from  it  with  greater  ease. 
One  of  the  important  considerations 
of  a  school  desk  is  the  proper  slope 
of  the  top.  It  is  well  known  that 
the  line  of  light  which  least  taxes 
the  eyes  should  fall  upon  the  print- 
ed page  perpendicularly  to  its  plane. 
To  accomplish  this  some  writers  rec- 
ommend a  slope  of  45°  for  the  desk 
top;  others  30°.  These  angles,  however,  are  not  practicable.  The  Vienna 
Expert  School  Desk  Commission  recommends  an  angle  of  15°  for  the 
desk  top,  which  is  also  approved  by  the  experiments  of  Shaw.  Such 
a  slope  permits  a  correct  posture  in  vertical  writing. 

A  foot  rest  is  sometimes  attached  to  desks.  The  weight  of  opinion 
is  now  against  foot  rests,  as  they  restrict  the  free  movement  of  the 
pupil's  feet  while  at  the  desk  and  interfere  with  opportunity  to  shift 
his  feet  and  legs  for  relief  from  inactivity,  and  further  interfere  with 
the  thorough  cleansing  of  the  floor  under  the  desk.  Shaw  recommends 
the  Heusinger  desk,  Fig.  152,  and  also  the  Ideal  desk.  The  desk  and 
seat  shown  in  the  accompanying  photograph,  Pig.  153,  are  known  as 
the  Boston  school  desk  and  chair.  There  are  now  many  thousands  in 
use  in  the  Boston  schools,  and  they  are  being  adopted  elsewhere. 

The  seat  and  chair  should  be  adjusted  for  each  pupil  when  he  enters 


Fig.  153. — Boston   School   Desk   and 
Chair. 


SCHOOLS  1085 

school  or  is  transferred  to  another  room.  Desks  and  seats  shoukl  be 
adjusted  at  least  twice  a  year :  at  the  opening  of  school  in  September 
and  again  in  February  or  March. 

The  Blackboard. — The  blackboard  should  be  placed  upon  the  wall 
opposite  the  principal  light.  The  board  should  not  have  a  shiny,  reflect- 
ing surface,  and  should  never  be  placed  between  windows  or  near  them. 

The  best  blackboards  are  made  of  slate,  as  they  can  be  washed,  which 
lessens  the  dust  nuisance.  The  best  slate  for  this  purpose  is  a  greenish 
or  strong  black  color,  which  is  to  be  preferred  to  the  grays  and  brown- 
ish-blacks. The  loss  of  light  by  absorption  can  be  reduced  greatly  by 
reducing  the  blackboard  area,  and  also  by  covering  the  blackboard  with 
adjustable  curtains.  Colored  crayons  made  with  arsenic  or  sulphid  of 
mercury  carry  danger  and  should  be  prohibited.  Dustless  crayons  may 
now  be  found  on  the  market. 

Posture. — Every  condition  must  be  eliminated  and  every  care  exer- 
cised to  prevent  the  acquiring  of  physical  defects  in  school,  as  well  as 
to  prevent  the  accentuation  of  those  physical  defects  which  the  child  may 
have  possessed  before  entering  school.  Posture  during  sitting  is  of  great- 
er consequence  than  posture  during  standing,  on  account  of  the  longer 
time  the  child  sits  and  the  muscular  fatigue  caused  by  the  inactivity  of 
a  great  number  of  muscles  of  the  body  for  a  long  period.  Stooping  over 
the  desk  leads  to  myopia;  it  also  contracts  the  chest  and  interferes  with 
free  respiration,  and  puts  additional  labor  on  the  heart;  it  leads  to 
round  shoulders  and  curving  of  the  spine  backward  and  a  carriage  in 
which  the  head  is  pitched  forward;  it  also  tends  to  displacement  of  the 
internal  organs,  both  of  the  abdomen  and  pelvis. 

In  order  that  the  pupil  may  be  in  a  proper  physical  condition  to 
maintain  an  erect  posture  while  in  his  seat,  and  thus  form  correct  habits 
which  he  vi^ill  carry  through  life,  he  must  be  given  periods  of  relief 
from  sitting  at  the  desk  and  corrective  exercises  at  different  times  dur- 
ing the  day.  In  the  first  year  the  child  should  not  be  confined  at  his 
desk  more  than  one-third  of  the  time.  In  the  succeeding  years  the  total 
amount  of  time  occupied  at  the  desk  may  be  gradually  lengthened.  In 
addition  to  the  regular  recesses  there  should  be  frequent  short  intervals 
of  resj^ite  from  sitting  at  the  desk  devoted  mostly  to  some  form  of  physi- 
cal exercise. 

A  recess  of  not  less  than  20  minutes  during  the  morning  session  and 
again  during  the  afternoon  session,  when  all  pupils,  if  the  weather  and 
climate  permit,  go  out  of  doors  and  engage  in  some  form  of  active  play, 
is  of  incalculable  value  in  its  results  upon  physical  health  and  mental 
development.  In  addition  there  should  be  given  to  each  grade  every 
school  day  at  least  two  short  periods  of  systematic  physical  drills  for 
pupils  and  teacher  with  the  windows  open. 

Lighting. — The  light  must  be  of  proper  intensity,  equally  diffused. 


1086  SCHOOLS 

and  come  from  the  projier  direction.  So  far  as  intensity  is  concerne<l 
the  light  must  be  neither  too  dim  nor  too  strong,  both  extremes  being 
harmful.  The  general  rule  is  that  the  amount  of  transparent  glass  sur- 
face admitting  light  should  be  from  one-sixth  to  one-fourth  of  the  floor 
space.  The  correct  amount  of  window  space  will  depend  on  the  loca- 
tion of  the  building,  direction  from  which  the  light  is  admitted,  size  and 
shape  of  the  room,  and  the  proximity  of  other  buildings  or  objects 
which  might  obstruct  the  light. 

The  amount  of  transparent  glass  surface  required  for  proper  illu- 
mination must  be  great  enough  to  afford  sufficient  light  on  rainy,  over- 
cast, and  cloudy  days.  Excessive  window  space  is  scarcely  possible,  for 
the  excess  illumination  on  bright  days  may  be  regulated  and  softened 
with  shades  and  awnings. 

The  amount  of  illumination  is  measured  by  candle  meters  or  candle 
feet ;  that  is,  the  illumination  afforded  by  a  standard  candle  at  a  distance 
of  one  meter  or  one  foot.  Shaw  ^  believes  that  the  illumination  should 
provide  at  least  50  candle  meters  in  the  most  unfavorable  part  of  the 
room. 

Factory-ribbed  glass  or  Luxfer  prisms  disperse  the  light  into  the 
parts  of  the  room  where  the  light  is  needed,  but  diminish  its  total 
amount;  they  are  of  advantage,  especially  where  schools  have  a  small 
amount  of  free  space  in  crowded  city  districts. 

The  principal  light  should  come  from  the  scholar's  left,  so  as  not  to 
throw  annoying  shadows  while  writing.  Windows  may  also  be  placed 
in  the  rear  of  the  scholars.  When  practicable  a  skylight  furnishes  the 
best  direction  for  illumination.  Windows  may  also  be  placed  at  the 
right  for  ventilating  purposes  or  for  admitting  direct  sunlight  while 
the  scholars  are  not  engaged  in  study.  The  window  sash  should  be 
3I/2  to  4  feet  from  the  floor  and  should  reach  as  near  the  ceiling  as  the 
construction  of  the  building  will  permit,  for  the  higher  the  windows 
reach,  the  deeper  the  light  penetrates  into  the  room.  Light  should  never 
enter  from  the  front  and  shine  in  the  pupils'  eyes.  Window  curtains 
should  be  "opaque"  and  of  a  greenish  cast.  The  upper  fourth  of  the 
window  furnishes  one-third  of  the  light,  also  the  best  light,  hence  it  is 
obvious  that  curtains  should  not  be  hung  from  the  top,  but  from  the 
bottom,  and  should  roll  upward.  Artists  have  long  learned  the  lesson 
that  light  from  above  follows  the  direction  of  nature  and  is  most  agTee- 
able  and  best.     (See  also  pages  706  and  1093.) 

Ventilation  and  Heating-. — Ventilation  of  the  school-room  is  of  para- 
mount importance.  There  is  a  great  waste  of  time  and  energy  of  both 
the  teacher  and  pupil  working  in  a  vitiated  atmosphere,  for  pure  air 
properly  conditioned  is  necessary  for  mental  work.  Bad  air  means  slug- 
gishness, headache,  listlessness,  inattention,  lack  of  energy,  and  a  depres- 

^  Shaw,  Edward  R. :   "School  Hygiene."     The  Macmillan  Co.,  N.  Y.,  1902. 


SCHOOLS  10S7 

sion  of  mental  vigor;  further,  bad  air  lowers  resistance  to  certain  dis- 
eases.   In  cold  climates  ventilation  and  heating  go  hand  in  hand. 

The  first  responsibility  in  a  poorly  ventilated  school  room  lies  with 
the  building  committees  because  of  their  failure  to  see  that  the  sum 
allowed  for  the  ventilating  plant  is  sufficient  to  give  the  best  that  science 
can  devise.  The  architect  often  skimps  the  ventilating  system  in  order 
to  provide  a  larger  and  more  ornate  building. 

In  favorable  climates  and  during  mild  weather  the  windows  should 
be  kept  open.  Even  during  cold  weather  the  windows  should  be  opened 
periodically  and  the  room  thoroughly  flushed  out  with  fresh  air.  The 
windows  should  always  be  thrown  open  at  recess  and  also  during  calis- 
thenic  drills  and  physical  exercises  and  also  at  the  close  of  sessions.  The 
experience  of  the  open-air  and  fresh-air  schools  teaches  that  cold  is  a 
fine  tonic  for  mind  and  body. 

Satisfactory  ventilation  by  means  of  windows,  except  in  rare  cases, 
is  impossible  on  account  of  varying  winds,  weather  conditions,  but  more 
especially  on  account  of  the  impossibility  of  securing  proper  attention 
on  the  part  of  the  average  teacher  to  the  matter  of  ventilation  in  addi- 
tion to  other  duties.  It  would  be  vastly  easier  to  get  one  man  for  each 
building  capable  of  operating  a  ventilating  plant  than  to  impose  this 
added  responsibility  upon  twelve  to  twenty  teachers. 

Every  school-room  with  a  proper  equipment  and  a  good  Janitor  may 
be  kept  well  ventilated  at  all  tines.  Many  good  ventilating  systems 
are  rendered  inefficient  through  the  employment  of  cheap  janitors.  A 
good  janitor  not  only  means  greater  efficiency,  but  a  saving  in  fuel  cost. 

Direct  radiation  from  stoves  or  steam  coils  or  hot-water  pipes  is 
inadvisable  for  school-rooms.  The  hot-air  furnace  may  be  used,  pro- 
vided the  air  is  sufficiently  moistened,  but  the  direct-indirect  system 
with  steam  or  hot-water  pipes  is  to  be  preferred.  Two  thousand  cubic 
feet  of  air  should  be  provided  for  each  scholar  hourly.  The  Massachu- 
setts law  requires  30  cubic  feet  of  pure  air  every  minute  per  pupil 
(1,800  cubic  feet  per  hour).  The  fresh-air  inlet  should  be  capacious 
and  separate  outlets  for  the  foul  air  should  be  provided.  The  cross- 
section  of  inlets  and  outlets  should  equal  from  16  to  20  square  inches 
for  each  scholar.  Ordinarily  it  is  preferable  to  place  both  inlets  and 
outlets  on  the  same  side  of  the  room,  viz.,  upon  the  inner  wall  or  warm 
side.  When  so  placed  i:he  warm  air  should  be  admitted  about  7  feet 
above  the  floor  and  the  foul  air  should  pass  out  close  to  the  floor. 

Special  attention  should  be  given  to  the  question  of  humidity,  so 
that  the  warmed  fresh  air  shall  not  be  excessively  dry. 

The  temperature  commonly  accepted  as  proper  for  a  school-room  is 
between  60°  and  68°  F:  The  children  would  probably  work  to  better 
advantage  if  the  temperature  were  kept  a  few  degrees  lower  and  the 
humidity  kept  so  that  the  wet  bulb  never  goes  above  70°  F.   (see  page 


]()S8  8r:nooT.s 

(!!)7).  A  thcrmomotcr  slionld  liuii.ii,'  iil.  iilioiit  tlui  hrcatliiji;^,-  line  in  every 
school-room  iind  the  l.e.i.clici'  slionld  lake  hunrly  I'cadin.^s  and  k(,'(,'p  a 
record.  The  temperature  of  school-ro(jms  is  usually  too  high,  and  those 
heated  with  the  hot-air  furnace  arc  usually  also  too  dry.  Both  ex- 
tremes are  prejudicial.  If  the  air  of  the  neighhorhood  is  smoky  and 
dusty  it  may  readily  be  filtered  before  it  is  pumped  into  the  school-room. 
The  combination  of  the  plenum  and  vacuum  systems,  the  air  being  driven 
by  rotary  fans,  is  one  of  the  best  methods  of  artificially  ventilating 
school-rooms.     (See  chapter  on  Ventilation.) 

Water-closets  and  ITrinals.— ^Separate  accommodations  must  be  pro- 
vided for  the  sexes;  privies  in  country  districts  should  be  in  entirely 
separate  buildings.  The  urinals  should  be  constantly  and  automatically 
flushed  and  water-closets  and  urinals  should  be  made  to  allow  complete 
inspection  and  use  of  the  scrubbing  brush.  Thorough  ventilation  of 
the  toilet-rooms  should  be  planned  for  and  they  should  be  kept  clean 
and  sweet  at  all  times. 

The  water-closets  may  be  in  the  basement  if  properly  constructed 
and  independently  ventilated.  The  floors  should  be  asphalted  to  facili- 
tate cleaning  and  flushing,  and  should  be  hosed  daily,  and  scrubbed  at 
least  once  a  week.  The  toilet-room  should  be  well  lighted.  Deodorizers 
should  not  be  used,  for  if  toilet-rooms  are  kept  clean  and  water- 
closets  well  flushed  they  will  not  be  necessary.  Urinals  should  be 
made  of  slate  or  hard  asphalt  or  other  non-absorptive  material, 
and  one  urinal  should  be  provided  for  each  fifteen  boys.  The  out- 
houses in  country  schools  should  be  properly  constructed  and  under  su- 
pervision. In  fact,  a  matron  should  be  in  attendance  to  assist  the  little 
tots  in  the  kindergarten  and  lower  elementary  grades,  and  a  watchful 
eye  on  the  part  of  the  master  of  the  school  and  those  he  delegates  for 
this  duty  should  be  kept  to  prevent  misbehavior  in  toilet-rooms. 

Cloak-rooms. — There  should  be  one  cloak-room  for  each  class-room, 
and  it  should  connect  both  with  the  hall  and  the  class-room.  Cloak- 
rooms should  be  lighted  from  the  outside,  heated,  and  thoroughly  ven- 
tilated to  carry  off  odors  and  to  dry  the  clothing.  Hanging  the  clothing 
in  the  halls  is  undesirable,  for  obvious  reasons.  Each  pupil  should  have 
a  shelf  on  which  to  lay  hats  and  small  articles,  hooks  upon  which  to  hang 
overcoats,  and  a  space  for  rubber  shoes  and  umbrella. 

Teachers  should  see  to  it  that  the  pupils  do  not  sit  in  wet  shoes  and 
stockings  or  in  wet  clothes.  Each  school  should  have  some  provision 
for  drying  wearing  apparel,  such  as  a  drying  chamber  which  may  be 
in  charge  of  the  janitor,  to  dry  the  wet  clothing  during  school  hours. 

Dressing-rooms  should  also  be  provided  for  the  teachers.  All  such 
rooms  and  lockers  should  be  kept  scrupulously  clean. 

Cleanliness. — Schools  should  be  kept  scrupulously  clean  and  every 
])rocaution  taken  to  prevent  dust.     Cleanliness  of  person  and  surround- 


SCHOOLS  1089 

ings  should  be  one  of  the  most  important  lessons  which  the  pupil  learns  at 
school.  Through  example  and  discipline  pupils  should  be  taught  to  love 
order  and  neatness  and  to  abhor  untidiness  and  slovenliness.  Cleanliness 
is  the  keynote  of  all  sanitation. 

Some  of  these  requirements  for  schools  are:  clean  drinking  water; 
bubbling  fountains  and  the  abolition  of  the  common  drinking  cup;  dis- 
continuance of  the  roller  towel,  cake  of  soap,  brush,  comb,  or  other 
toilet  articles  used  in  common;  cleanliness  of  floors,  desks,  corridors, 
cloak-rooms,  toilet-rooms,  basement,  and  grounds;  the  prohibition  of 
dry  sweeping  or  dusting.  Blackboards  should  be  washed  frequently  to 
avoid  the  dust  nuisance,  and  the  floors  may  be  treated  with  one  of 
the  dustless  floor  oils.  The  windows  should  be  kept  clean,  and  each 
child  should  have  his  individual  books,  pencils,  and  other  accessories. 
Health  Day,  observed  annually,  gives  a  special  opportunity  to  emphasize 
the  importance  of  hygiene  and  cleanliness. 

Medical  Inspection  of  Schools. — The  medical  inspection  of  schools 
is  no  longer  an  experiment,  but  a  pressing  necessity.  It  is  founded  on 
a  recognition  of  the  close  connection  which  exists  between  the  physical 
and  mental  condition  of  children  in  the  whole  process  of  education.  It 
seeks  to  secure  ultimately  for  every  child,  normal  or  defective,  con- 
ditions of  life  compatible  with  that  full  and  efl'ective  development  of  its 
organic  functions,  its  special  senses,  and  its  mental  and  spiritual  powers 
which  constitute  a  true  education. 

The  object  of  a  medical  inspection  of  schools  is  not  primarily  the 
treatment  of  diseases,  but  rather  their  prevention.  One  of  the  principal 
objects  is  the  early  recognition  of  physical  defects  such  as  errors  of  re- 
fraction, imperfect  hearing,  malformations  of  the  body  from  abnormal 
positions,  adenoids,  enlarged  tonsils,  and  other  obstructions  of  breath- 
ing, and  sources  of  inflammation,  etc.  An  important  object  of  the  med- 
ical inspection  of  school  children  is  to  determine  their  fitness  to  enter 
school  and  to  recognize  mental  and  nervous  disorders;  also  the  early 
recognition  of  the  communicable  diseases  and  measures  to  prevent  their 
spread;  the  supervision  of  vaccination,  and  disinfection;  the  teaching  of 
personal  hygiene  to  pupils  and  teachers,  and  the  sanitation  and  clean- 
liness of  the  school  building  and  its  surroundings;  the  adjustment  of 
the  seat  and  desk,  and  the  medical  supervision  of  the  mental  and  physical 
work  of  the  child. 

Medical  inspection  of  schools  is  making- slow  progress.  A  systematic 
school  inspection  was  started  in  Brussels  in  1874  and  in  Paris  in  1884, 
since  which  time  the  movement  has  become  world-wide.  In  America 
the  first  systematic  inspection  of  school  children  was  begun  in  1894, 
after  four  years'  effort  by  Dr.  Samuel  H.  Durgin,  Commissioner  of 
Health  of  Boston,  who  is  regarded  as  the  father  of  the  system  through- 
out America.  The  first  scientific  and  extensive  examination  of  school 
36 


1090  SCHOOLS 

children  was  made  by  Dr.  Henry  P.  Bowditeh/  whose  essay  upon  "The 
Growth  of  Children  Studied  by  Galton's  Method  of  Percentile  Grades" 
has  become  a  classic  in  the  subject.  In  1908  there  were  only  seventy 
cities  outside  of  Massachusetts  having  medical  inspection  of  schools. 
Massachusetts  has  a  compulsory  medical  inspection  law ;  New  Jersey  has 
a  permissive  one;  Vermont  has  a  law  requiring  an  annual  testing  of 
the  vision  and  hearing  of  all  school  children,  and  Connecticut  one  pro- 
viding for  such  tests  triennially. 

Physical  defects  are  not  equally  significant  either  from  the  medical 
or  from  the  pedagogical  standpoint.  Each  kind  of  defect  should  be 
separately  studied,  and  classification  should  not  include  pediculosis  with 
defective  vision;  club-foot  with  defective  hearing;  adenoids  with  ring- 
worm. 

The  objects  of  the  medical  inspection  of  schools  may  be  greatly  as- 
sisted by  teaching  the  teachers  the  elementary  facts  concerned. 

Medical  inspection  of  schools  was  organized  in  this  country  for  the 
purpose  of  controlling  the  communicable  diseases  of  childhood.  It  must 
at  once  be  admitted  that  it  has  been  a  failure  so  far  as  this  object 
is  concerned,  for  it  has  had  very  slight  influence  upon  the  prevalence 
of  measles,  scarlet  fever,  diphtheria,  whooping-cough,  mumps,  etc.  Theo- 
retically we  would  expect  a  good  system  of  medical  inspection  of  school 
children  to  check  the  prevalence  of  these  diseases.  Perhaps  it  does 
so  to  a  limited  extent.  With  improvements  in  the  system  and  enthusi- 
asm in  the  cause  much  may  still  be  accomplished  along  these  lines. 

There  has  been  much  discussion  concerning  who  shall  conduct  the 
medical  inspection.  It  is  plain  that  in  any  system  the  teacher  must  be 
the  ultimate  inspector,  and  teachers  are  quite  competent  to  carry  out  sim- 
ple tests  for  determining  the  acuteness  of  vision  and  hearing.  In  one 
sense  the  teacher  is  the  foster  mother  of  the  child  and  frequently  knows 
the  child  better  than  its  own  mother.  The  teacher  should  report  to 
the  medical  inspector  children  who  show  any  of  the  following  symptoms : 
loss  of  weight,  pallor,  pufBness  of  the  face,  shortness  of  breath,  swellings 
in  the  neck,  general  lassitude,  growing  pains,  rheumatism,  flushing  of 
the  face,  eruptions  of  any  sort,  cold  in  the  head,  especially  running  eyes, 
irritating  discharge  from  the  nose,  evidence  of  sore  throat,  cough,  vomit- 
ing, or  frequent  requests  to  go  to  the  toilet. 

The  next  most  important  link  in  the  chain  of  a  good  system  of 
medical  inspection  is  the  nurse.  She  is  able  to  detect  the  beginning 
symptoms  of  disease  and  can  be  trusted  to  care  for  simple  troubles.  The 
chief  value  of  the  school  nurse,  perhaps,  is  in  establishing  communica- 
tion with  the  home  and  securing  friendly  cooperation  with  the  parents. 
Parental  neglect  is  rarely  due  to  the  lack  of  parental  affection,  but  to 

*  Twenty- second  Annual  Report,  State  Board  of  Health  of  Mass.,  1890,  pp. 
479-522. 


SCHOOLS  1091 

ignorance.  The  nurse  is  frequentl}'  able  to  gain  the  confidence  of  both 
child  and  parent  when  the  medical  inspector  fails.  The  nurse,  further, 
will  assist  the  medical  staff  in  carrying  out  treatment.  One  of  the  chief 
duties  of  the  school  nurse  is  social  service. 

It  is  because  of  the  nurse's  important  place  in  public  health  work 
that  it  is  better  to  have  medical  school-inspection,  together  with  its  valu- 
able follow-up  work,  lodged  with  the  health  authorities  rather  than  with 
the  educational  authorities. 

It  is  the  duty  of  the  medical  inspector  to  detect  defects,  not  to  treat 
them.  Who  shall  treat  the  child  is  a  matter  for  the  parents  or  guardian 
to  decide.  It  is  not  sufficient  merely  to  notify  parents  that  the  child 
needs  treatment,  for  frequently  no  attention  is  paid  to  the  notices.  The 
child  may  be  referred  to  or  taken  by  the  school  nurse  to  the  hospital  or 
outclinic.  In  some  districts  school  clinics  have  been  instituted  with 
success. 

Duties  of  the  Medical  Inspectors. — An  ideal  system  of  medical 
inspection  of  schools  would  consist  of  a  corps  of  trained  and  competent 
physicians  and  sanitarians  who  would  devote  their  entire  time  to  this 
special  work.  The  staff  should  have  the  assistance  of  experts  in  ven- 
tilation and  heating,  experts  in  sanitary  architecture,  experts  in  sanitary 
engineering,  and  experts  in  the  various  medical  specialties. 

Specialists  should  visit  all  school  buildings  no  less  than  three  times 
each  year  in  order  to  investigate  all  matters  of  heating,  lighting,  and 
ventilation,  cleanliness,  gymnasiums,  bath,  and  toilets,  and  the  seat- 
ing arrangements  with  reference  to  the  size  of  the  pupils;  the ■  purity  of 
the  drinking  water,  the  quality  of  the  food  purchased  by  the  children  at 
the  recess  period,  and  the  general  conditions  of  the  neighborhood  that 
may  affect  the  health  of  the  pupils. 

Furthermore,  cooperation  between  the  medical  and  pedagogical  de- 
partments should  be  helpful  in  solving  the  many  difficult  prohlems  con- 
cerning the  curriculum. 

In  addition  to  these  general  inspections  all  children  entering  school 
should  be  examined  medically  at  least  once  during  each  school  year.  The 
first  examination  is  for  the  purpose  of  establishing  whether  the  child 
is  fit  for  school  and  can  do  the  work  without  injury  either  to  its  mental 
or  physical  well-being.  The  second  should  be  a  physical  examination, 
which  may  be  made  more  thorough  if  the  child  is  required  to  strip. 
This,  however,  should  not  be  done  unless  the  parents  of  the  child  are 
present  or  give  their  consent.  The  third  examination  consists  of  special 
tests  of  the  eyes,  ears,  nose,  throat,  and  teeth. 

Aside  from  these  regular  exaixdnations  the  school  physician  must 
respond  to  every  call  when  a  pupil  comes  to  school  having  an  eruption, 
fever,  or  other  symptoms  indicating  a  communicable  disease.  The  med- 
ical inspectors  should  also  oversee  disinfection,  vaccination,  and  certify 


1093  SCHOOLS 

the  return  to  school  of  any  child  who  has  hecn  out  of  school  l>y  reason 
of  a  communicahle  disease. 

The  Communicable  Diseases  of  Childhood. — Parents  naturally  come 
to  regard  the  school  as  a  veritable  pesthouse  for  the  spread  of  the  com- 
municable diseases  of  childhood — especially  measles,  whooping-cough, 
mumps,  diphtheria,  scarlet  fever,  chicken-pox,  common  colds,  etc.  Many 
of  these  diseases  prevail  in  epidemic  form  during  the  summer  time, 
when  school  is  closed,  and  under  other  circumstances  which  show  that 
epidemics  may  be  independent  of  school  attendance.  It  is  difficult  to 
determine  just  what  part  is  played  by  the  commingling  of  the  pupils 
in  school  in  the  spread  of  such  diseases  and  what  part  is  due  to  other 
factors.  Some  diseases  take  a  sudden  jump  in  the  autumn  with  the 
opening  of  school.  Further,  these  diseases  are  not  contracted  by  the 
school  children  alone,  but  are  carried  home  to  the  other  members  of 
the  household,  and  thereby  create  secondary  foci.  This  problem  of  the 
communicable  diseases  and  the  schools  is  far  from  solution;  the  spread 
of  these  diseases  has  not  been  conquered  by  medical  inspection,  and  their 
relation  to  school  attendance  is  one  that  needs  careful  observation  and 
study. 

A  difference  is  made  between  exclusion  on  accoimt  of  disease  and 
that  due  to  exposure.  In  the  latter  case  the  period  of  exclusion  is  based 
upon  the  period  of  incubation  of  the  disease.  Immunes  are  not  excluded. 
Carriers  should  be  looked  for. 

Closing  Schools  on  Account  of  Epidemics. — The  question  of  closing 
the  schools  when  some  one  of  these  diseases  breaks  out  is  often  a  difficult 
one  to  decide.  If  the  children  commingle  out  of  school,  upon  the  streets 
and  playgrounds,  no  useful  purpose  is  accomplished  by  closing  the 
schools.  Hence  closing  schools  is  usually  more  effective  in  country  dis- 
tricts than  in  cities.  Closing  schools  is  economically  wasteful  and  usually 
has  no  influence  on  the  course  of  an  outbreak.  Children  are  less  apt  to 
infect  each  other  in  the  class-room  than  in  the  home  or  on  the  play- 
ground. As  a  rule  better  results  will  be  achieved  by  daily  inspection  of 
all  school  children  than  by  closing  the  schools.  At  the  beginning  of  an 
outbreak  the  schools  may  be  closed  for  the  period  of  incubation  and 
then  opened,  but  careful  guard  must  be  exercised  to  discover  new  cases 
and  a  watch  kept  over  the  return  of  convalescents.  Under  these  cir- 
cumstances a  daily  inspection  should  be  conducted  before,  and  not  after, 
the  children  enter  school.  If  closing  the  schools  during  the  period  of 
incubation  is  not  effective  nothing  will  be  gained  by  prolonging  the 
period.     See  also  measles,  scarlet-fever,  diphtheria. 

A  special  lookout  must  be  kept  for  carriers,  and  laboratory  facilities 
provided  to  detect  the  same. 

The  diseases  for  which  children  should  be  excluded  from  school  are: 
smallpox,  scarlet  fever,  measles,   German   measles,   chicken-pox,   diph- 


SCHOOLS  1093 

theria,  tonsillitis,  whooping-cough,  pediculosis,  mumps,  scabies,  trachoma, 
ringworm,  impetigo  contagiosa,  venereal  disease,  pulmonary  tuberculosis, 
influenza. 

The  Eyes. — Errors  of  refraction  are  exceedingly  common,  and  if  not 
corrected  are  the  cause  of  headache,  nervousness,  reflex  pains,  and  a 
great  variety  of  symptoms.  They  are  also  a  great  handicap  to  the 
mental  and  physical  development  of  the  child.  The  vision  of  all  chil- 
dren should  be  tested  annually,  and  at  least  once  for  color-blindness. 
It  has  been  shown  that  the  unnatural  strain  of  accommodating  the  eyes 
to  close  work  (for  which  they  were  not  intended)  leads  to  myopia  in  a 
large  proportion  of  growing  children.  Thus  the  percentage  of  myopia 
increases  markedly  from  the  primary  classes  through  the  grammar 
grades,  and  is  highest  in  the  high-schools.  The  eyes  should  therefore 
be  tested  and  errors  of  refraction  corrected  at  least  once  a  year.  There 
are  certain  children  who  show  normal  vision  by  the  ordinary  tests  ( Snel- 
len test  type),  yet  whose  eyes  should  be  examined  by  an  expert  if  they 
habitually  hold  the  head  too  near  the  book  (less  than  12  to  ll  inches)  ; 
or  if  they  frequently  complain  of  headache,  especially  in  the  latter  por- 
tion of  school  hours;  or  if  one  eye  deviates  even  temporarily  from  the 
normal  position.  The  following  symptoms  also  indicate  trouble  with 
the  eyes,  viz.,  scowling  and  wrinkling  of  the  forehead  when  reading  or 
writing,  watery  eyes,  reddened  or  granular  lids,  twitching  of  the  face, 
inattention,  and  slowness  in  book  studies  in  a  child  otherwise  bright. 

The  conditions  which  are  especially  hard  upon  the  eyes  are  dim  light, 
improper  angle  of  vision,  small  print,  and  prolonged  focusing  at  close 
range.    Type  for  books  should  not  be  smaller  than  the  following: 


Type 


Width  of  Leading 


First  year 

Second  and  third  years. 

Fourth  year 

Above  this  grade 


2.6  mm. 
2.0  mm. 
1.8  mm. 
1.6  mm. 


4.5  mm. 
4.0  mm. 

3.6  mm. 
3.0  mm. 


In  addition  to  the  size  the  characters  should  be  simple,  the  ink 
black,  and  printed  upon  paper  with  a  mat,  unreflecting  surface  that  is 
free  from  gloss.  Paper  of  a  grayish  tone  is  to  be  avoided  and  the  paper 
should  be  thick  enough  or  of  such  quality  that  the  print  does  not  show 
through  from  the  back.  Pupils  should  be  taught  that  it  is  advisable 
while  reading  or  during  other  close  focusing  of  the  eyes  occasionally  to 
look  away  and  accommodate  for  distance  to  relieve  the  tension  and 
counteract  the  tendency  to  myopia.     (See  also  pages  706  and  1086.) 

The  Ears. — It  has  been  found  that  approximately  15  per  cent,  of 
school  children  possess  some  defect  of  hearing  either  in  one  or  both 
ears.    Defective  hearing  is  frequently  mistaken  for  inattention  upon  the 


1094  SCHOOLS 

part  of  the  pupil,  for  which  lie  may  be  unjustly  punished.  Practical 
tests  to  determine  the  acuteness  of  hearing  should  "he  made  separately 
with  each  ear  by  the  use  of  a  watch  or  by  the  whisper  voice.  Dis- 
charges from  the  ears,  known  as  abscesses  in  the  ears,  or  earache  should 
at  once  be  reported  to  the  proper  medical  attendant. 

The  Teeth. — The  proper  use  of  the  toothbrush  and  silk  floss  to  keep 
the  surfaces  and  spaces  between  the  teeth  clean  should  be  impressed 
upon  every  pupil.  For  young  children  silk  floss  is  not  advisable  if 
the  space  between  the  teeth  is  filled  with  soft  tissue.  The  teeth  should 
be  examined  by  a  competent  dentist  at  least  once,  and  preferably  twice, 
a  year.  In  the  light  of  our  present  knowledge  it  is  an  outrage  to  allow 
caries  of  the  teeth  to  develop  into  toothache  before  children  are  taken 
to  a  dentist.  Irregularities  of  the  teeth,  especially  those  which  make  it 
impossible  to  close  the  mouth  properly,  lead  to  faulty  digestion,  to  mouth 
breathing,  and  other  defects.  The  first  permanent  molars  (6-year 
molars)  are  perhaps  the  most  important  teeth  in  the  mouth,  and  are 
the  most  frequently  neglected  because  they  are  so  often  mistaken  for 
temporary  teeth.  It  should  be  known  that  decay  of  the  teeth  is  caused 
primarily  by  the  fermentation  of  starchy  foods  and  sugars,  so  that  the 
greatest  factor  in  preventing  dental  caries  is  the  removal  of  food  particles 
by  frequent  brushing  and  the  use  of  the  silk  floss.  Children  should  be 
discouraged  from  eating  crackers  and  candy  between  meals  and  the  teeth 
should  be  cleaned  after  each  meal. 

To  provide  expert  dental  attention  for  all  carious  teeth,  including 
the  temporary  set,  would  overtax  the  facilities  of  any  community.  Den- 
tal clinics  should  be  provided  in  which  caries  of  the  temporary  teeth 
should  have  at  least  temporary  treatment.  It  should  be  remembered  that 
one  infected  tooth  is  like  a  rotten  apple  in  a  barrel  in  that  it  is  apt  to  in- 
volve the  others. 

Nose  and  Throat. — The  noses  and  throats  of  all  pupils  should  be 
examined  for  any  cause  of  obstruction  to  respiration,  particularly  ade- 
noids, polypi,  deviation  of  the  septum,  etc.  Nosebleed  should  always  be 
reported  and  inquiry  should  be  made  as  to  mouth-breathing  during 
sleep.  In  all  cases  of  acute  illness  the  throat  and  mouth  should  be 
examined  for  indications  of  scarlet  fever  or  measles  and  for  the  signs 
of  tonsillitis  or  diphtheria,  and  a  culture  should  be  taken  in  any  sus- 
pected case  of  diphtheria.  The  presence  of  a  discharge  from  the  nose 
should  be  noted,  and  if  it  is  thick  and  creamy  a  culture  should  always 
be  taken.  If  the  discharge  from  the  nose  is  only  from  one  nostril  a 
foreign  body  or  local  cause  should  be  looked  for.  Adenoids  may  be  in- 
ferred from  mouth-breathing,  snoring,  chronic  post-nasal  catarrh,  or 
recurring  ear  trouble.  Pupils  with  obviously  large  tonsils,  recurring 
tonsillitis,  and  enlargement  of  the  glands  of  the  neck  should  be  referred 
to  a  physician  for  treatment. 


SCHOOLS  1095 

Diseases  of  the  Skin. — Apart  from  the  exanthemata  the  diseases  of 
the  skin  which  are  of  importance  because  communicable  are:  scabies, 
pediculosis,  ringworm,  and  impetigo. 

Scabies. — All  children  who  are  scratching  or  have  an  irritation  on 
the  skin  should  be  examined  for  scabies  (the  itchmite).  It  is  important 
that  all  infected  members  of  the  family  be  treated  until  cured,  else  the 
disease  is  passed  back  and  forth  from  one  to  another.  It  is  also  im- 
portant that  all  clothing,  bedding,  towels,  etc.,  and  similar  things  that 
come  in  contact  with  the  body  be  boiled  each  time  they  are  washed.  All 
cases  of  scabies  should  be  excluded  from  school  until  cured.  Sulphur 
ointment  is  usually  efficacious. 

Pediculi  Capitis. — Pediculi  capitis  (head  lice)  are  extremely  com- 
mon among  children,  and  are  communicated  directly  and  also  by  wearing 
each  other's  hats  or  hanging  them  on  each  other's  pegs,  or  from  combs 
and  brushes.  Every  child  should  have  its  own  brush  and  comb.  These 
should  be  cleaned  by  immersion  in  boiling  water.  jSTo  person  should  be 
blamed  for  having  lice,  only  for  keeping  them.  The  condition  may  be 
suspected  by  the  teacher  in  children  who  show  indications  of  irritation 
of  the  scalp,  and  the  condition  is  easily  detected  by  looking  for  the 
eggs  (nits),  which  are  small  white  objects  adhering  to  the  hair.  Head 
lice  are  best  treated  by  killing  the  living  parasites  with  crude  petroleum 
and  then  getting  rid  of  the  nits.  With  boys  this  is  easy ;  a  close  haircut  is 
all  that  is  needed.  With  girls  a  fine-tooth  comb  wet  in  alcohol  or  vinegar, 
which  dissolves  the  attachment  of  the  eggs  to  the  hair,  may  be  used. 
All  combs  and  brushes  used  should  be  carefully  washed  and  disinfected. 
Children  with  pediculi  should  be  excluded  from  school  until  their  heads 
are  clean.     (See  also  page  294.) 

EiNGWOEM. — Ringworm  of  the  skin  yields  readily  to  treatment,  but 
upon  the  scalp  is  extremely  chronic.  When  the  disease  attacks  the  scalp 
the  hair  falls  off  or  breaks  off  near  the  scalp,  leaving  areas  the  size  of 
a  dime  or  dollar  nearly  bald.  The  scalp  in  these  areas  is  usually  dry 
and  somewhat  scaly,  but  may  be  swollen  and  crusted.  The  disease 
spreads  at  the  circumference  of  the  area  and  new  areas  arise  from 
scratching,  etc.    The  diagnosis  is  made  by  looking  for  the  fungus. 

Favus. — Favus  is  a  disease  somewhat  allied  to  ringworm,  more  com- 
mon in  Europe  than  in  America.  In  this  disease  quite  abundant  crusts 
of  a  yellowish  color  are  present  when  the  process  is  active.  The  roots 
of  the  hair  are  killed  by  the  Achorion  sclionleinn,  so  that  loss  of  hair 
from  this  disease  is  permanent,  a  scar  remaining  when  the  condition  is 
cured. 

Children  with  ringworm  or  favus  should  not  be  allowed  to  attend 
school  unless  the  lesions  are  properly  dressed  and  covered  with  collodion. 
Children  should  be  taught  to  use  their  own  brushes  and  combs  and  not 
to  wear  each  other's  hats,  caps,  etc.    In  some  districts  special  schools  are 


1096  SCHOOLS 

maintained  for  favus  and  for  ringworm  of  the  scalp,  where  the  pupils 
receive  treatment. 

Impetigo. — Impetigo  is  a  disease  characterized  Ijy  pustules  which 
appear  on  the  face,  neck,  and  hands,  less  often  upon  the  body  and  scalp. 
The  size  of  the  pustules  varies  very  much  and  they  often  run  together  to 
form  on  the  face  large  superficial  sores  covered  with  thick,  dirty,  yellow- 
ish, or  brownish  crusts.  The  disease  is  contagious  and  spreads  by  scratch- 
ing as  well  as  by  using  common  towels  and  other  things.  Children  hav- 
ing impetigo  should  not  be  allowed  to  attend  school  until  all  the  sores 
are  healed  and  the  skin  smooth. 

Nervous  Diseases  and  Mental  Defects. — A  sharp  lookout  for  indica- 
tions of  diseases  of  the  nerves  and  of  mental  defects  should  be  kept  and 
especial  notice  taken  of  suggestive  symptoms  in  a  child  who  did  not 
formerly  show  them.  The  teacher  should  be  taught  to  report  instances 
of  restlessness  or  inability  to  stand  or  sit  quietly  in  a  previously  quiet 
child,  especially  if  to  this  are  added  irritability  of  temper  and  loss  of 
self-control,  such  as  crying  for  trifles  or  inability  to  keep  the  attention 
fixed. 

Chokea. — Twitching  of  the  muscles,  the  result  of  disease,  may  cause 
the  child  to  drop  things,  render  his  work  awkward,  or  interfere  with 
writing  or  drawing.  Such  children  are  too  often  scolded  for  being  in- 
attentive or  careless.  The  indications  of  chorea  (St.  Vitus's  dance) 
should  not  be  confounded  with  habit-spasms  such  as  blinking  of  the 
eyelids  or -the  slower  twitching  movements  of  the  face  or  shoulders  or 
other  parts  of  the  body,  which  may  be  due  to  defects  of  vision,  adenoid 
growths,  or  other  reflex  causes.  Cases  of  chorea  should  be  removed 
from  school  at  once,  both  for  the  child's  safe  and  to  prevent  an  epidemic 
of  imitative  movements  such  as  sometimes  occurs.  Children  with  habit- 
spasms  need  not  be  withdrawn  from  school  work,  although  these  condi- 
tions often  require  treatment. 

Epilepsy. — Mild  epileptic  attacks  (petit  mat)  are  frequently  over- 
looked or  misunderstood  by  the  teacher.  They  may  be  mistaken  for 
fainting.  Usually  these  attacks  are  only  momentary,  in  which  the  child 
stares  fixedly  and  does  not  reply  to  questions  or  in  which  he  suddenly 
stops  speaking  or  whatever  he  is  doing  and  is  unaware  of  what  is 
going  on  about  him.  The  lapse  of  consciousness  is  one  of  the  charac- 
teristic features  of  epilepsy.  The  attack  may  be  accompanied  by  rolling 
up  of  the  eyes,  drooling,  or  unusual  movements  of  the  lips ;  an  epileptic 
fit  often  appears  like  a  choking  attack.  Teachers  very  frequently  mis- 
understand epileptic  attacks  and  cannot  be  expected  to  distinguish  them 
from  hysterical  convulsions  and  other  diseases.  It  does  not  necessarily 
follow  that  cases  of  epilepsy  should  be  withdrawn  from  the  school,  but 
medical  advice  should  always  be  had. 

Neurasthenia. — Neurasthenia  or  nerve  fatigue  may  be  shown  by 


SCHOOLS  1097 

irritability  or  sleeplessness  and  other  indications  threatening  a  nervous 
breakdown.  This  may  be  due  to  irregular  habits,  want  of  proper  sleep, 
lack  of  suitable  food,  poor  hygienic  conditions,  or  simply  from  the  child 
being  pushed  in  school  beyond  his  physical  or  mental  capacity.  Exces- 
sive fear  or  morbid  ideas,  bashfulness,  undue  sensitiveness,  causeless  fits 
of  crying,  morbid  introspection,  and  self -consciousness  may  also  be  symp- 
toms of  a  neurasthenic  condition,  and  call  for  investigation  and  for  the 
teacher's  sympathy  and  winning  of  the  child's  confidence  to  prevent 
developments  of  a  more  serious  nature.  Excitability  is  often  the  first 
stage  of  fatigue  and  is  frequently  mistaken  for  brightness  and  therefore 
encouraged. 

The  teacher  should  know  that  forgetfulness,  loss  of  interest  in  work 
and  play,  desire  for  solitude,  untidiness  in  dress  or  person,  and  like 
changes  of  character  are  sometimes  incidental  to  the  period  of  puberty. 

Defectives. — Mentally  defective  children  in  the  public  schools  ex- 
hibit certain  common  characteristics  which  soon  become  evident.  The 
typical  incorrigible  child  of  the  primary  grades  often  is  a  mentally  de- 
fective child  of  the  excitable  type.  They  are  destructive,  cruel  to  smaller 
children,  and  often  precocious  sexually.  Certain  cases  show  marked 
moral,  deficiency.  Mentally  defective  children  must  be  distinguished 
from  those  who  are  only  temporarily  backward  as  a  result  of  some  re- 
movable cause  such  as  defective  vision,  impaired  hearing,  adenoid 
growths,  or  as  a  result  of  unhappy  home  conditions,  irregular  habits, 
want  of  proper  sleep,  lack  of  suitable  food,  bad  hygienic  conditions,  etc. 
Teachers  should  refer  to  the  medical  inspectors  for  examination  children 
who,  without  obvious  cause,  such  as  absence  or  ill  health,  show  them- 
selves unable  to  keep  up  in  their  school  work,  who  are  unable  to  fix  their 
attention,  or  are  incorrigible. 

A  careful  lookout  should  be  kept  for  children  showing,  sexual  per- 
version, for  one  sexual  pervert  may  demoralize  a  whole  school. 

Vaccination. — Vaccination  should  be  required  of  all  children  before 
they  are  permitted  to  attend  school.  The  evidence  of  a  successful 
vaccination  usually  accepted  is  a  physician's  certificate  or  a  characteris- 
tic sear.  For  the  indices  of  a  successful  take  see  page  11.  School 
children  should  be  vaccinated  before  entering  school  and  again  before 
entering  high  school. 

REFERENCES 

* 

The  following  references  have  been  used  in  the  preparation  of  this 
chapter,  especially  the  books  of  Shaw  and  Hogarth. 

Shaw,  Edward  R.:     "School  Hygiene."     The  Macmillan  Co.,  N.  Y.,  1902. 

Hogarth,  A.  H.:  "Medical  Inspection  of  Schools."  Oxford  Medical 
Publications,   London,   1909. 

Gulick,  L.  H.,  and  Ayres,  L.  P.:  "Medical  Inspection  of  Schools."  New 
York  Charities  Publication  Committee,  MCMVIII. 


1098  SCHOOLS 

Stevens,  E.  M.:  "Medical  Supervision  in  Schools."  Bailli^re,  Tindall, 
and  Cox,  liOndon,  1910. 

Dressier,  Fletcher  B.:     "School  Hygiene."     Macmillan,  1913. 

Cornell.  "Health  and  Medical  Inspection  of  School  Children."  "Medical 
Inspection  of  School  Children."  A  Summary  of  Existing,  Legislation,  Issued 
by  Council  on  Health  and  Pubhc  Instructions  of  the  Amer.  Med.  Assn.,  1912. 

Baginscky,  Adolf:  "Handbuch  der  Schulhygiene. "  Bd.  I,  1898;  Bd.  II, 
1900.     Ferdinand  Enke,  Stuttgart. 

Transactions  of  the  International  Congress  on  School  Hygiene. 

Zeitschrift  f.  Schulyesundheitspflege. 

Bowditch,  H.  P.:  "The  Growth  of  Children  Studied  by  Galton's  Method 
of  Percentile  Grades."  Twenty-second  Annual  Report  of  the  State  Board 
of  Health  of  Mass.,  1890,  pp.  479-522. 

Weyl,  Theodor:  "Handbuch  der  Hygiene."  Vol.  VII,  Erste  Abt,  Schul- 
hygiene, Jena,  1895. 


SECTION  XII 
DISINFECTION 

CHAPTER  I 
GENERAL  CONSIDERATION'S 

Disinfection. — Disinfection  means  the  destruction  of  the  agents  caus- 
ing infection.  An  object  is  said  to  be  infected  when  contaminated  with 
pathogenic  microorganisms.  It  is  disinfected  by  destroying  these  or- 
ganisms, whether  they  are  in  the  substance  or  on  the  surface  of  that 
object.  Disinfection,  then,  deals  only  with  destroying  the  vitality  of 
those  minute  forms  of  life  which  cause  disease.  It  does  not  mean  the 
destruction  of  all  the  lower  forms  of  animal  and  vegetable  life  that  may 
be  in  or  upon  an  object — this  is  sterilization. 

Disinfecting  procedures  properly  applied  have  an  important  part  in 
the  prevention  of  communicable  diseases.  Their  efficiency  decreases  as 
the  distance  between  the  place  of  origin  of  the  infection  (the  patient) 
and  the  point  of  their  application  is  increased. 

Sterilization. — All  processes  which  sterilize  necessarily  disinfect, 
but  all  disinfecting  processes  by  no  means  sterilize.  The  distinction  be- 
tween disinfection  and  sterilization  arises  principally  from  the  fact 
that  spores  have  a  much  greater  resistance  to  all  influences  which  de- 
stroy the  vegetative  cells.  Fortunately,  none  of  the  pestilential  diseases 
of  man  which  "occur  in  widespread  epidemics,  so  far  as  known,  are  caused 
by  microorganisms  with  resistant  spores;  therefore  the  usual  processes 
of  disinfection  may  be  thoroughly  efficient,  yet  leave  many  harmless  and 
hardy  forms  of  microscopic  life  alive.  In  other  words,  sterilization  is 
rarely  necessary  in  public  health  work,  except  in  the  case  of  anthrax, 
tetanus  and  other  spore-bearing  infections  such  as  malignant  edema 
and  the  gas  bacillus  group. 

Antiseptics. — Antiseptic  substances  prevent  decomposition  and  de- 
cay. Such  substances  retard  or  prevent  the  growth  and  activity  of  micro- 
organisms, but  do  not  necessarily  destroy  them ;  that  is,  antiseptics  delay 
or  prevent  fermentation  and  putrefaction  without  destroying  the  micro- 
organisms which  cause  these  processes.  There  is  a  great  difference  be- 
tween the  antiseptic  and  the  disinfecting  power  of  most  substances.  For 
instance,  a  solution  of  formalin  will  restrain  the  development  of  most 

1009 


1100  DISINFECTION 

bacteria  in  the  proportion  of  1  to  r)0,0()0,  bnt  it  requires  a  3  to  10  per 
cent,  solution  of  this  liquid  to  kill  the  l)acteria  in  a  reasoiial)ly  short  time. 
As  weak  a  solution  of  bichlorid  of  mercury  as  1  to  300,000  will  sometimes 
prevent  the  germination  of  anthrax  spores,  whereas  it  reqiiires  a  1  to 
1,000  solution  to  destroy  them.  Saturated  solutions  of  salt  or  sugar 
will  preserve  meat,  vegetables,  and  other  organic  substances;  that  is,  they 
are  antiseptic  in  their  action  but  not  germicidal,  as  they  have  small 
powers  of  destroying  microorganisms. 

Asepsis. — Asepsis  means  freedom  from  or  absence  of  living  patho- 
genic microorganisms  and  is  practically  equivalent  to  sterilization. 
Surgical  asepsis  may  be  achieved  through  physical  cleanliness. 

Geemicide. — A  germicide  is  a  substance  or  agent  which  destroys 
germs.  Germicides  and  disinfectants  are  interchangeable  terms,  as 
both  are  used  to  indicate  the  destruction  of  microorganisms.  Many 
germicides  used  in  public  health  work  are  potent  enough  to  sterilize 
objects  with  which  they  come  in  contact. 

Deodorant. — A  deodorant  is  a  substance  which  has  the  power  to 
destroy  or  to  neutralize  the  unpleasant  odors  arising  from  organic  mat- 
ter undergoing  fermentation  or  putrefaction.  Such  substances  must  be 
distinguished  carefully  from  disinfectants.  Deodorants  destroy  smells; 
disinfectants  destroy  germs.  Many  of  the  disinfecting  agents  are  also 
deodorants,  but  all  deodorizing  substances  are  by  no  means  disinfectants. 
For  example,  charcoal  will  absorb  the  malodorous  gases  arising  from 
putrefying  and  fermenting  materials,  but  it  is  inert  so  far  as  its  power 
to  destroy  the  cause  of  these  processes  is  concerned.  Formalin,  on  the 
other  hand,  is  a  true  deodorant  and  disinfectant,  as  it  combines  with 
the  organic  matter  to  form  new  compounds  which  are  both  odorless 
and  sterile.  Bichlorid  of  mercury,  while  a  very  potent  germicide,  has 
practically  no  immediate  effect  upon  odors.  The  volatile  oils  and  other 
substances  having  a  pungent  odor  are  not  deodorants ;  they  simply  cover 
up  one  smell  with  another. 

Fumigation. — Fumigation  consists  in  liberating  fumes  or  gases  with 
the  object  of  destroying  germs,  vermin,  insects,  rats,  mice  and  other 
small  animals  acting  as  carriers  of  infection.  The  chief  fumigants  used 
in  public  health  work  are  f ormaldehyd  and  sulphur  dioxid ;  to  a  less  ex- 
tent carbon  monoxid,  funnel  gases,  hydrocyanic  acid,  pyrethrum,  carbon 
bisulphid,  chlorin,  etc.  Most  of  these  are  very  poisonous  to  higher  forms 
of  life,  but  have  little  or  no  germicidal  power — excepting  formaldehyd 
which  is  a  good  germicide,  but  feeble  insecticide.  Fumigation  cannot 
take  the  place  of  disinfection ;  gases  at  best  have  but  the  merest  surface 
action.  As  they  lack  the  power  of  penetration  they  cannot  be  depended 
upon  to  disinfect  even  thin  fabrics,  or  surfaces  soiled  with  sputum  or 
similar  discharges  in  which  the  virus  is  protected  against  the  fumigating 
gas, 


GENEEAL    CONSIDEEATIONS  1101 

The  terms  fumigation  and  disinfection  have  been  much  confused. 
Because  fumigation  is  not  necessary  or  ineffective  after  some  of  the  com- 
municable diseases — the  word  has  gone  forth  that  disinfection  is  unnec- 
essary and  useless.  JSTo  mistake  could  be  greater.  Fumigation  has  its 
place  and  its  limitations  in  public  health  work — so  also  disinfection. 

Nature's  Disinfecting  Agencies. — In  nature  many  forces  are  con- 
stantly at  work  to  destroy  infection  and  thereby  limit  the  spread  of 
the  communicable  diseases.  It  is  the  duty  of  the  sanitarian  to  encourage 
the  use  of  these  natural  disinfecting  agencies;  they  are  dilution,  sun- 
light, dryness,  time  and  symbiosis.  Sunlight  is  a  great  destroyer  of  germ 
life.  Few  microbes,  especially  the  pathogenic  ones,  can  live  in  the  direct 
bright  sunlight  many  hours.  Dryness  is  another  natural  condition  that 
is  destructive  to  many  of  the  minute  forms  of  life  Avith  which  we  have 
to  contend.  The  combination  of  dryness  and  sunlight  is  quite  as  good, 
if  not  better,  than  the  ordinary  fumigating  processes  which  are  com- 
monly used  in  practical  disinfection  against  surface  contamination. 
Dryness,  sunlight,  and  cleanliness  are  the  keynotes  of  sanitation  in  the 
modern  acceptation  of  the  term. 

We  now  know  that  most  of  the  pathogenic  microorganisms  do  not 
grow  and  multiply  in  our  environment.  For  the  most  part  they  soon  die 
when  wafted  into  the  air,  deposited  on  surfaces,  conveyed  in  water  or 
placed  in  the  soil.  It  is  only  occasionally  that  some  of  them  find  condi- 
tions favorable  for  development  in  foods  such  as  milk  and  meat,  and  ex- 
ceptionally in  water.  Further,  it  is  to  be  noted  that  ordinarily  it  requires 
a  certain  number  of  microorganisms  to  produce  infection.  It  is  quite 
likely  that  a  single  typhoid  bacillus  or  a  single  tetanus  spore  may  "kindle 
a  conflagration."  Experimental  evidence  with  the  infections  upon  labor- 
atory animals  teaches  the  lesson  that  ordinarily  an  animal  is  capable  of 
taking  care  of  minute  amounts  of  infection,  particularly  if  attenuated. 
It  requires  ten  tubercle  bacilli  to  cause  tuberculosis  in  a  guinea-pig. 
Dilution,  attenuation,  and  the  conditions  of  our  environment,  unfavor- 
able to  most  germs  harmful  to  man,  therefore  protect  us  in  no  small 
measure  against  the  communicable  diseases.  This  is  the  reason  why  so 
many  of  the  communicable  infections  are  contracted  largely  through  close 
personal  association. 

Cleanliness. — Cleanliness  is  a  very  important  adjunct  to  the  work  of 
disinfection.  In  fact,  cleanliness  lies  at  the  base  of  all  our  sanitary  meas- 
ures. The  mere  act  of  cleaning  removes  some  of  the  adherent  microbes 
from  the  surface  and  the  ordinary  scrubbing  and  washing  result  in  the 
final  destruction  of  many  more.  Dry  dusting  and  sweeping  serve  only 
to  stir  up  dust  and  infection,  which  settle  down  again  upon  the  same 
or  other  surfaces.  Cleanliness  serves  another  important  purpose,  so 
far  as  infection  is  concerned ;  it  removes  the  organic  matter  on  which 
and  in  which  bacteria  may  find  favorable  conditions  for  prolonging  life 


1102  DISINFECTION 

and  virulence.  The  modern  eojicoptioii  of  cleanliness  has  expanded  wJtli 
the  growth  of  the  sanitary  sciences.  We  now  aim  at  hiologic-al  cleanliness 
as  well  as  esthetic  cleanliness.  This  includes  not  only  the  removal  of 
organic  matter,  but  the  destruction  of  insects  and  vermin,  and  Uuii' 
feeding  and  breeding  places.  (See  page  781.)  So  far  as  personal  clean- 
liness is  concerned,  the  two  important  acts  to  prevent  infection  are:  (1) 
Washing  the  hands  before  eating,  before  handling  food  and  after  leav- 
ing the  toilet;  and  (2)  keeping  the  fingers  away  from  the  mouth  and 
nose. 

The  surfaces  frequently  used  or  handled  by  the  public,  such  as  wood- 
work, seats,  floors,  desks,  door  handles  and  the  like  in  schools,  stores, 
factories,  shops  and  public  conveyances  and  assembly  places  should, 
when  practicable,  be  frequently  scrubbed  with  hot  soap-suds  and  strong 
soda  solution.  This  also  includes  the  seats  of  water-closets  and  privies, 
wash-basins,  and  other  objects  used  in  common. 

In  the  wholesale  disinfection  which  must  be  practiced  to  check  wide- 
spread epidemic  diseases  due  to  bacterial  infection  we  are  largely  limited 
to  the  use  of  the  agents  which  nature  has  constantly  at  work  to  destroy 
such  infection.  Against  a  single  case  of  communicable  disease  or  against 
a  limited  infected  area  we  may  employ  aggressive  measures  such  as 
steam  and  strong  chemicals;  but  when  a  disease,  due  to  bacterial  infec- 
tion, has  spread  over  an  extensive  district  these  methods  must  be  sup- 
plemented by  all  the  resources  of  nature.  The  people  must  be  educated 
so  as  individually  to  employ  intelligent  measures  to  avoid  the  infection. 
Cleanliness  must  be  more  scrupulously  practiced  than  ever,  simlight  and 
dryness  must  be  given  their  fullest  opportunity  to  operate  even  at  the 
expense  of  a  few  faded  carpets  or  colors. 

Antibiosis  and  Symbiosis. — Many  pathogenic  microorganisms  are 
destroyed  in  the  process  of  putrefaction  and  fermentation.  They  die  in 
the  fierce  struggle  for  existence  going  on  in  these  processes  of  decom- 
position. For  the  most  part  the  hardier  saprophytic  forms  of  life  over- 
power and  kill  the  disease-producing  microorganisms  which  have  com- 
paratively feeble  powers  of  resistance.  The  fact  that  infected  carcasses, 
sewage,  and  putrid  organic  matter  generally  purify  themselves  by  the 
very  processes  that  destroy  them  is  a  fortunate  provision  of  nature. 

When  and  Where  to  Disinfect. — It  naturally  suggests  itself  that  it 
is  much  better  to  prevent  infection  than  to  be  compelled  to  destroy  it 
after  it  has  become  disseminated  through  ignorance,  carelessness,  or  neg- 
ligence. It  is  the  duty  of  the  disinfector  to  destroy  infection  wherever 
it  is  found;  it  is  the  ideal  of  the  sanitarian  to  prevent  the  spread  of 
infection  so  as  to  render  broadcast  disinfection  unnecessary. 

The  best  place  to  apply  disinfection  is  at  the  seat  of  origin  of  the 
infection.  Man  is  the  fountain-head  of  most  of  the  infections  to  which 
he  is  heir;  hence  the  most  effective  place  to  apply  disinfectants  is  at 


GEI^EEAL    CONSIDERATIONS  1103 

the  bedside.  The  excretions,  especially  those  from  the  month,  nose,  and 
bowels,  as  well  as  discharges  from  eruptions  and  wounds  most  frequently 
need  attention.  When  proper  precautionary  measures  have  been  taken  at 
the  bedside  with  a  case  of  cholera,  typhoid  fever,  or  plague  there  is  little 
need  of  subsequently  disinfecting  the  sickroom,  but  when  a  diffusion 
of  the  infection  results  then  a  general  disinfection  becomes  necessary. 

ftualifications  of  the  Disinfector. — The  disinfection  of  any  given 
place  is  a  complex  operation,  and  should  not  be  attempted  by  anyone  not 
familiar  with  the  peculiarities  of  the  particular  infection  with  which 
he  has  to  deal  and  a  thorough  knowledge  of  the  disinfecting  agents  em- 
ployed. In  other  words,  it  is  quite  as  important  to  know  what  to  disin- 
fect as  how  to  disinfect  and  when  to  disinfect.  A  thorough  understand- 
ing of  the  causes  and  modes  of  transmission  of  the  communicable  dis- 
eases is  the  most  useful  weapon  the  disinfector  has  in  his  fight  against 
the  spread  of  infection. 

The  success  of  the  disinfector  lies  in  personal  attention  to  minute 
details.  Germs  are  little  things,  and  it  is  little  things  that  count  in  this 
kind  of  work.  The  disinfector  who  is  satisfied  to  leave  the  process  in 
the  hands  of  an  inexperienced  person  with  a  few  words  of  instruction 
cannot  expect  to  obtain  trustworthy  results.  The  disinfector  must  give 
personal  surveillance  to  the  whole  process — the  materials,  the  strength  of 
solutions,  modes  of  application — and  must  be  present  to  guide  and  direct 
every  step  of  the  operation  with  the  same  conscientiousness  and  thor- 
oughness with  which  the  surgeon  assures  himself  of  every  detail  of 
asepsis  in  his  operating-room. 

Much  of  the  routine  disinfection  done  by  departments  of  health  is 
probably  ineffective,  although  the  procedure  is  faithfully  carried  out 
as  a  routine.  The  average  disinfecting  squad  does  not  understand  the 
effect  of  temperature,  humidity,  oiitside  winds,  porosity  of  walls,  shape 
and  size  of  enclosures,  and  the  rate  of  application  of  the  disinfection 
and  other  factors. 

Controls. — Every  disinfecting  process  should  be  controlled  by  exposing 
cultures  upon  paper  slips  or  threads  as  a  guide  and  check  to  the  thor- 
oughness of  the  process.  This  may  perhaps  best  be  done  by  saturating 
threads  with  an  active  culture  of  B.  prodigiosus.  ,  These  threads  are  at- 
tached to  little  slips  of  paper  which  are  then  exposed  in  various  portions 
of  the  room  to  be  disinfected.  After  the  completion  of  the  operation  the 
threads  are  inoculated  into  Dunham's  peptone  medium.  If  the  B.  prodi- 
giosus has  survived  the  characteristic  red  color  appears  in  the  culture 
medium. 

Disinfection  Must  Be  in  Excess  of  Requirements. — The  disinfection 
of  rooms,  bedding,  ships,  and  objects  that  have  been  exposed  to  infection 
must  of  necessity  be  greatly  in  excess  of  the  actual  requirements.  This 
is  one  of  the  difficulties  met  with  in  attacking  an  invisible  foe.     A  sick- 


1104  DISINFECTION 

room  might  readily  be  disinfected  and  rendered  safe  by  applying  a  few 
gills  of  one  of  the  germicidal  solutions  to  a  small  spot  or  a  limited 
area.  But,  as  we  cannot  see  the  germs,  it  is  necessary  to  apply  our 
disinfecting  agents  to  every  inch  of  surface  of  the  room  and  all  its  con- 
tents in  order  not  to  miss  that  particular  spot.  At  first  disinfection  was 
directed  by  a  shotgun  process  in  a  general  sort  of  blunderbuss  way 
against  everything,  but  now  that  we  knoAv  more  about  the  habits  and 
habitat  of  each  one  of  the  particular  microorganisms  we  can  concen- 
trate our  efforts  with  some  exactness  upon  the  particular  objects  liable 
to  transmit  infection,  and  with  greater  assurance  of  eradicating  danger. 

The  Ideal  Disinfectant. — The  ideal  disinfectant  must  first  and  fore- 
most possess  a  high  germicidal  power.  It  must  not  be  rendered  ineffec- 
tive by  the  presence  of  organic  matter;  it  must  be  reasonably  stable,  so 
as  not  to  deteriorate  under  ordinary  conditions;  it  must  be  soluble  or 
readily  miscible  in  water ;  if  it  forms  an  emulsion  the  emulsion  should  be 
permanent;  it  should  be  harmless  to  man  and  the  higher  animals;  it 
should  have  the  power  of  penetration;  it  should  not  corrode  metals, 
bleach,  rot  or  stain  fabrics,  and,  finally,  it  should  be  reasonable  in  price. 

The  stress  of  modern  activities  demands  disinfecting  processes  that 
are  instantaneous  in  their  action,  all-pervading  in  their  effects,  cheap, 
harmless,  and  free  from  unpleasant  odors  that  might  be  offensive  to 
the  fastidious.  Such  perfect  disinfectants  are  not  known.  It  requires 
money  and  the  expenditure  of  well-directed  and  intelligent  energy  to 
accomplish  satisfactory  disinfection.  No  one  substance  is  applicable  to 
all  diseases  or  to  all  substances,  or  even  to  the  same  disease  or  the  same 
substance  under  different  conditions. 

Terminal  Disinfection. — Terminal  fumigation  during  recent  years  has 
been  disparaged  as  a  public  health  measure  because  it  has  little  effect 
upon  the  control  of  the  communicable  diseases  and  the  cost  of  such 
disinfection  appears  to  be  disproportionately  large  to  the  benefits.  The 
evident  limitations  of  terminal  fumigation  have  cast  doubt  in  the  minds 
of  some  health  officers  upon  the  value  of  disinfection  in  general.  This  is 
an  unfortunate  attitude.  No  one  can  question  the  great  value  of  disin- 
fection properly  applied.  It  is,  of  course,  niuch  more  important  to  de- 
stroy the  infective  discharges  throughout  the  course  of  a  case  of  typhoid 
fever  than  to  trust  to  one  final  disinfection  of  the  sick-room  and  its 
contents.  The  same  holds  with  about  equal  force  for  most  of  the  com- 
municable diseases.  We  now  know  that  fomites  play  a  comparatively 
minor  role  in  the  transmission  of  disease.  The  disinfection  of  rooms 
and  objects  does  not  now,  therefore,  hold  the  importance  in  the  minds 
of  sanitarians  that  it  once  did.  The  principal  objects  that  need  disinfec- 
tion are  the  discharges  from  the  body;  towels,  bedding,  handkerchiefs 
and  fabrics;  food;  tableware  and  other  objects  that  have  been  mouthed, 
and  finally  the  hands  of  the  nurse,  physician  and  others  who  come  in 


GENEBAL    COXSIDERATIO^Tg  1105 

contact  with  the  infection.  However,  if  terminal  disinfection  prevents 
the  occurrence  of  only  a  small  number  of  cases  it  would  still  seem  to  he 
worth  while.  Moreover,  wha»t  health  officer  would  willingly  allow  his 
child  to  occupy  the  bed  or  handle  the  objects  in  a  room  soon  after  a 
case  of  typhoid,  scarlet  fever,  tuberculosis,  or  diphtheria  without  first 
applying  some  effective  method  of  purification  ?  The  greater  the  care 
and  cleanliness  exercised  during  the  progress  of  the  disease  the  less 
the  need  of  terminal  disinfection.  So  long  as  we  possess  such  a  reason- 
ably efficient  and  satisfactory  substance  as  formaldehyd,  terminal  disin- 
fection should  be  practiced  after  ail  diseases  in  which  the  environment 
may  become  infected,  even  though  the  danger  be  slight. 

The  distinction  between  fumigation  and  disinfection  must  be  kept 
clearly  in  mind  (see  page  1100).  Terminal  fumigation  for  measles  and 
for  certain  other  frail  and  short-lived  viruses  may  not  be  necessary,  but 
disinfection  of  objects  likely  to  convey  disease  will  always  be  demanded. 

Penetration. — In  practical  disinfection  a  certain  amount  of  penetra- 
tion is  almost  always  called  for.  Most  germicides  penetrate  poorly  and 
slowly.  As  a  rule,  substances  in  solution  penetrate  better  than  substances 
in  emulsion.  Gaseous  subtances  cannot  be  depended  upon  to  penetrate 
at  all.  They  have  only  the  merest  surface  action.  Feces  and  sputum 
are  not  only  the  most  difficult  to  penetrate,  but  also  the  most  important 
because  so  apt  to  contain  virulent  pathogenic  microorganisms  through- 
out their  mass.  No  germicidal  agent  can  be  depended  upon  to  permeate 
a  fecal  mass  under  ordinary  conditions  in  a  reasonable  time.  It  is, 
therefore,  most  important  that  such  substances  be  thoroughly  disinte- 
grated and  the  germicide  incorporated  throughout  the  mass.  Bacteria 
in  nature  are  usually  imbedded  in  various  substances  which  differ 
greatly  in  consistency  and  composition,  and  therefore  practical  disinfec- 
tion calls  for  stronger  solutions  and  longer  time  than  indicated  by  labora- 
tory tests  upon  the  naked  germ  cells.  In  certain  instances,  where  pene- 
tration is  required,  trust  should  only  be  placed  in  steam,  dry  heat,  or 
boiling.  None  of  the  ordinary  chemicals  can  be  trusted  to  penetrate  up- 
holstered furniture,  mattresses,  pillows,  thick  blankets  and  the  like. 

Albuminous  Matter. — Albuminous  matter  seriously  interferes  with  the 
efficiency  of  almost  all  germicidal  agents.  Chlorinated  lime  and  potas- 
sium permanganate  attack  albuminous  matter  with  avidity  and  are  thus 
soon  used  up.  The  metallic  salts  coagulate  albuminous  matter,  thus 
automatically  impeding  further  ingress.  Formaldehyd  and  phenol  show 
less  reduction  of  power  in  the  presence  of  albuminous  matter  than  per- 
haps any  of  the  other  germicides. 

In  nature,  bacteria  are  usually  imbedded  in  albuminous  matter. 
The  way  in  which  albuminous  matter  handicaps  germicidal  action  has 
been  shown  by  many  investigators.  Behring  found,  for  example,  that 
anthrax  bacilli  suspended  in  water  are  killed  in  a  few  minutes  with 


1106  DISINFECTION 

bichlorid  of  mercury  1-500,000 ;  in  bouillon  it  required  1-40,000 ;  while 
in  blood  serum  1-2000  was  not  always  effective. 

Time. — Time  is  an  essential  factor  too  frequently  disregarded  in  dis- 
infecting with  liquids  in  suspension  or  solution.  Very  few  chemical  dis- 
infectants act  instantly,  even  in  strong  solutions  and  under  favorable 
conditions.  The  microorganisms  are  so  often  in  clusters  or  are  sur- 
rounded by  mucoid  films  or  are  so  imbedded  in  organic  matter  that  a 
considerable  time  is  required  for  the  disinfecting  solution  to  penetrate  to 
the  germ.  If  the  microbes  are  dry  it  takes  a  certain  time  to  wet  them 
before  the  chemical  can  act.  These  and  other  factors  must  be  added  to 
the  time  actually  necessary  for  the  substance  to  destroy  the  life  of  the 
germ  after  it  comes  in  direct  contact  with  it. 

It  is  well-known  that  some  germicides,  particularly  the  metallic  salts, 
if  given  sufficient  time,  will  eventually  kill  in  exceedingly  weak  dilu- 
tions. Mercuric  chlorid,  according  to  Chick  and  Martin,  will  act  as  a 
germicide  in  a  dilution  of  1  to  1,000,000  if  given  sufficient  time.  The 
action  of  copper  sulphate  in  exceedingly  weak  dilutions  on  algae  is  also 
of  interest  in  this  connection.  Some  disinfectants,  on  the  other  hand, 
exert  their  most  useful  action  promptly,  and  are  then  rapidly  used  up 
by  being  decomposed,  or  otherwise  lose  their  power. 

Chick  found  a  logarithmic  ratio  between  concentration  of  disinfect- 
ant and  the  time  taken  to  disinfect.  She  found,  furthermore,  that  the 
phenol  coefficient  of  mercuric  chlorid  with  B.  typhosus  varies  greatly 
with  the  prolongation  of  exposure.     Thus : 

Phenol  coefficient  of  HgCla    2 . 5  minute  exposure  =    13 . 5  coefficient. 
«  «  «       «      30  «  «        =  550  « 

This  is  an  interesting  side  light  on  the  Eideal- Walker  technic  which, 
until  recently,  permitted  a  latitude  of  time  of  comparison  varying  from 
2%  to  15  minutes.  This  wide  variation  of  the  coefficient,  however,  is 
found  mainly  in  the  case  of  the  metallic  salts. 

Time  is  an  exceedingly  important  element  in  disinfection.  It  is  not 
sufficient  to  simply  dip  the  hands  in  and  out  of  a  bichlorid  solution, 
to  rinse  fabrics  in  carbolic  acid  solution,  or  to  pour  formalin  over  feces. 
It  takes  time  to  penetrate  and  then  to  kill. 

Temperature. — There  is  a  complete  analogy  existing  between  a  chem- 
ical reaction  and  disinfection,  one  reagent  being  represented  by  the  dis- 
infectant and  the  other  by  the  protoplasm  of  the  bacterium.  Chick  states 
that  the  velocity  of  disinfection  increases  with  the  rise  in  temperature  in 
a  manner  similar  to  that  of  a  chemical  reaction.  In  fact,  the  tempera- 
ture so  greatly  influences  the  disinfecting  power  of  liquids  that  it  is 
strongly  recommerider]  always  to  use  warm  solutions  in  actual  practice. 
Even  slight  changes  of  tomporatnre  niny  make  a  great  differeneo.     Feeble 


GENERAL    CONSIDEEATIONS  1107 

antiseptic  solutions  become  strong  germicides  when  warmed.  Phelps 
claims  that  as  the  temperature  increases  arithmetically,  the  velocity  of 
reaction  increases  geometrically.  This  is  not  a  general  rule  applicable 
for  all  disinfectants,  for  Chick  showed  that  the  germicidal  power  of  the 
metallic  salts  increases  2  to  4  fold  for  each  rise  of  10°  C,  while  phenol 
usually  rises  7  to  8  fold  for  each  similar  change  in  temperature. 

A  good  instance  of  the  effect  of  temperature  is  given  by  Heiden,  who 
found  that  anthrax  spores  which  survived  the  effects  of  a  5  per  cent, 
carbolic  solution  for  36  days  at  room  temperature  were  destroyed  in 
half  an  hour  in  the  same  solution  at  55°  C.  At  75°  C.  it  took  only  3 
minutes  to  kill  them.  A  3  per  cent,  carbolic  acid  solution  killed  the 
same  spores  at  this  temperature  in  15  minutes  and  a  1  per  cent,  solu- 
tion in  from  2  to  2i/2  hours. 

Emulsions  and  Solutions. — As  a  rule  an  emulsion  has  greater  germi- 
cidal power  than  a  solution.  Thus  soapy  and  resinous  emulsions  of  the 
phenols  may  accentuate  the  germicidal  power  of  these  substances.  Chick 
and  Martin  have  observed  that  the  particles  of  an  emulsion  or  soapy 
preparation  of  the  coal-tar  acids  exhibit  active  Brownian  motion.  The 
bacteria  are  considerably  larger  than  the  mean  diameter  of  the  emulsi- 
fied particles.  The  bacteria  may  plainly  be  seen  to  be  bombarded  by 
these  particles.  In  this  way  the  bacteria  are  frequently  brought  into 
intimate  contact  with  the  undiluted  particles  of  pure  coal-tar  acids. 
The  maximum  effect  may  therefore  be  obtained  and  the  death  of  the  bac- 
teria is  inevitable.  Such  a  concentration  is  less  likely  to  occur  with  sub- 
stances in  solution.  The  coal-tar  acids  in  suspension  act  upon  the  bac- 
teria first  through  physicochemical  adsorption,  and  secondarily  through 
chemical  combination.  The  bacteria  rapidly  become  surrounded  by  the 
disinfectant  in  a  much  greater  concentration  than  actually  exists  within 
the  liquid.  Other  particulate  matters  present  have  the  same  power  of 
adsorption,  and  their  presence  therefore  interferes  with  the  germicidal 
value  of  -substances  in  emulsion.  Thus  the  value  of  phenol  is  barely  im- 
paired by  the  presence  of  organic  matter  in  solution,  while  emulsified  dis- 
infectants are  reduced  to  one-third  or  one-half  their  original  value.  That 
germicidal  substances  in  emulsion  fail  to  penetrate  may  be  demonstrated 
by  pouring  one  of  the  coal  tar  emulsions  upon  a  fecal  mass ;  a  visible  layer 
of  the  coal-tar  creosotes  soon  collects  upon  the  surface,  plainly  visible 
as  a  film. 

Dilution. — It  is  not  enough  in  applying  any  agent  whose  best  working 
strength  is  known  to  use  a  small  volume  of  the  solution  of  that  particular 
strength.  There  must  be  a  sufficient  amount  of  the  substance  used  so 
that  it  shall  be  present  throughout  the  whole  mass  in  the  proportion  re- 
quired. Thus  an  agent  that  is  effective  in  a  2  per  cent,  solution  cannot 
be  used  in  that  strength  to  disinfect  an  equal  volume  of  an  infected 
liquid,  since  the  mixture  would  then  contain  but  1  per  cent.     This  is 


1108  DISINFECTION 

particularly  important  in  the  disinfection  of  urijie,  feces,  sputum,  vom- 
itus  and  tlie  like. 

Reaction.. — The  reaction  of  the  solution  and  of  the  medium  to  be  dis- 
infected varies  with  the  substance  employed.  Thus  lime  is  an  alkali,  and 
if  used  to  disinfect  an  acid  substance  enough  must  first  be  added  to 
neutralize  the  medium  and  then  an  additional  amount  of  lime  must  be 
added  necessary  to  accomplish  the  disinfection.  In  the  same  way,  if 
mercuric  chlorid  is  added  to  solutions  containing  sulphids,  caustic 
alkalis,  or  certain  metallic  salts,  sufficient  must  be  added  in  order  to 
first  precipitate  these  substances  and  then  enough  more  added  to  exert 
its  disinfecting  action.  Likewise,  the  greater  the  number  of  germs  to 
be  destroyed  the  greater  the  amount  of  the  disinfectant  required  to  ac- 
complish the  purpose. 

How  the  Bacteria  Are  Killed. — Chemical  substances  act  in  a  great 
variety  of  ways  to  bring  about  the  destruction  of  bacteria.  Just  how 
the  microbes  are  poisoned  is,  in  many  instances,  an  unsolved  problem  in 
toxicology.  In  particular  cases  there  appears  to  be  a  chemical  union 
between  the  disinfectant  and  the  protein  of  the  bacteria,  as  appears  to  be 
the  case  with  corrosive  sublimate  or  f ormaldehyd.  In  some  instances  the 
protein  of  the  cell  is  coagulated,  as  in  the  case  of  carbolic  acid  and 
homologous  substances.  It  has  been  shown  that  the  higher  the  grade 
of  dissociation  the  greater  is  the  disinfecting  power  of  the  solution.  Thus 
in  the  case  of  the  soluble  metallic  salts,  and  especially  mercury,  it  de- 
pends upon  whether  in  the  electrolytic  dissociation  the  metal  exists  as  an 
independent  ion  or  whether  it  exists  as  a  complex  ion.  In  the  first  case 
the  solution  has  strong  germicidal  properties ;  in  the  second  these  proper- 
ties are  much  weaker.  In  other  liquids,  as,  for  example,  alcohol,  ether, 
etc.,  the  metallic  salts  have  very  slight  dissociation  which,  according  to 
Kronig  and  Paul,  explains  the  weaker  disinfecting  power  of  these  solu- 
tions. The  disinfecting  power  of  metallic  salts  depends,  furthermore, 
not  only  upon  the  influence  of  the  metal  ion,  but  also  upon  the  other 
ions  and  ui3on  the  unassociated  parts  of  the  metallic  salts. 

The  manner  in  which  disinfectants  destroy  bacteria  may  be  divided 
into  4  groups : 

(1)  Destruction  by  oxidation  as  ozone,  chlorinated  lime,  potassium 
permanganate  and  the  halogens. 

(2)  Destruction  by  ionic  poison  with  coagulation,  as  the  metallic 
salts. 

(3)  Destruction  by  coagulation  and  poisoning  not  ionic  in  char- 
acter, as  carbolic  acid  and  phenol  derivatives. 

(4)  Destruction  by  emulsoid  action,  that  is,  through  Brownian 
movement  and  absorption. 

The  Choice  of  Germicide. — The  choice  of  the  chemical  to  be  used 
depends  somewhat  on  the  nature  of  the  substance  to  be  disinfected,  as 


THE  STANDAEDIZATION  OF  DISINFECTANTS       1109 

well  as  upon  the  resistance  of  the  virus.  Ordinary  germicidal  solutions, 
such  as  bichlorid  of  mercury,  1-1000,  or  carbolic  acid,  21/2  per  cent.,  can- 
not be  trusted  to  kill  tetanus  spores;  emulsions  are  not  serviceable  for 
the  disinfection  of  feces;  a  weak  chlorinated  lime  will  disinfect  water, 
but  a  strong  solution  is  necessary  to  disinfect  fabrics,  but  the 
strong  solution  bleaches  and  rots  the  fiber.  Certain  chemicals 
have  a  selective  action  and  appear  to  be  specific  poisons  for  some  organ- 
isms as,  for  example,  copper  sulphate  for  algae.  On  the  other  hand, 
carbolic  acid  is  particularly  ineffective  against  the  virus  of  smallpox. 
Taken  altogether,  therefore,  the  choice  of  the  chemical,  its  strength,  and 
time  of  application,  the  temperature  of  the  solution,  and  its  method  of 
employment,  are  all  problems  which  must  be  solved  for  each  particular 
class  of  infection,  and  each  particular  grouj)  of  substances. 


THE  STANDARDIZATION  OF  DISINFECTANTS 

There  is  no  accurate  standard  by  which  the  power  of  disinfecting 
agents  may  be  measured.  There  are  conditions  influencing  the  life  of 
the  bacterial  cell  which  we  are  unable  to  control.  It  is  for  this  reason 
that  the  strengths  of  solutions  necessary  to  disinfect  are  variously  stated 
by  different  authorities,  and  the  time  of  exposure  is  for  the  same  reason 
not  always  definitely  decided.  The  difficulty  in  this  connection  is  to  deter- 
mine the  minimum  conditions  which  will  furnish  trustworthy  results 
and  still  provide  a  coefficient  of  safety  necessary  for  general  practice.  Of 
still  greater  importance  is  the  fact  that  our  laboratory  tests  do  not  imi- 
tate the  natural  conditions  under  which  bacteria  are  commonly  found  in 
nature.  The  requirements  of  practical  disinfection  are  therefore  usually 
much  more  severe  than  the  conditions  of  our  laboratory  tests. 

While  the  results  of  scientific  work  in  the  laboratory  must  be  our 
guide  as  to  the  value  and  efficiency  of  any  disinfecting  process  we  can- 
not ignore  the  results  of  experience  gained  in  actual  practice  in  combat- 
ing the  communicable  diseases.  This  is  especially  true  of  disinfectants 
used  against  a  disease  the  cause  of  which  is  only  surmised  or  the  mode  of 
transmission  not  definitely  known.  We  have  had  a  lesson  on  this  point 
in  the  case  of  sulphur.  This  substance  had  long  been  used  as  a  disin- 
fectant for  yellow  fev^r,  and  practical  experience  had  justified  the  con- 
fidence placed  in  sulphur  fumigation  to  check  the  spread  of  this  disease, 
but  when  the  scientific  tests  made  in  the  laboratory  showed  that  sulphur 
dioxid  is  a  very  poor  germicide,  discredit  was  thrown  upon  it;  now  that 
we  know  that  sulphur  dioxid  is  one  of  the  best  insecticides,  confidence 
has  been  restored  both  as  to  the  scientific  and  practical  value  of  this 
substance. 

On  the  other  hand,  laboratory  experiments  have  established  with 


1110  DISINFECTION 

great  accuracy  the  value  and  reliability  of  certain  disinfectants  which 
otherwise  would  have  gone  begging.  Thus  the  value  of  corrosive  sub- 
limate, chlorinated  lime  and  formaldehyd  was  established,  while  on  the 
other  hand  some  substances,  such  as  zinc  chlorid  and  sulphate  of 
iron,  have  been  robbed  of  the  high  place  in  which  they  were  formerly 
held  and  placed  near  the  bottom  of  the  list  of  disinfectants.  Even 
carbolic  acid  has  been  shown  to  have  less  germicidal  power  than  was 
formerly  supposed. 

Methods  of  Standardizing  Disinfectants. — Priugle  ^  as  early  as  1750 
attempted  to  standardize  the  then  known  antiseptics  by  determining 
their  power  to  preserve  (i.  e.,  prevent  decomposition  in)  a  mixture 
consisting  of  2  grains  of  meat  and  60  grains  of  sea  salt  in  2  ounces  of 
water.  Following  Pringle's  work  little  was  accomplished  for  over  100 
years  in  standardizing  disinfectants  until  Koch  started  a  new  era  by  the 
use  of  pure  cultures  and  the  "thread  method." 

The  Thread  Method. — Koch  ^  in  1881  used  pure  cultures  of  B. 
prodigiosus,  B.  pyocya^ieus,  and  B.  antliracis,  both  with  and  without 
spores.  He  soaked  threads  in  a  culture  of  the  test  organism  and  after- 
ward dried  them  for  various  periods  and  then  exposed  these  infected 
threads  to  the  action  of  the  disinfectant  to  be  tested.  The  threads  were 
then  washed  and  laid  on  the  surface  of  a  solid  nutrient  medium  and 
incubated  for  growth.  This  method,  although  characterized  by  greater 
scientific  accuracy  than  the  methods  previously  used,  lacked  perhaps 
those  broader  features  of  the  older,  rougher  experiments;  that  is,  the 
method  did  not  approximate  the  conditions  met  with  in  practical  disin- 
fection closely  enough.  Koch's  reports,  so  favorable  to  bichlorid  of  mer- 
cury, gave  a  great  impetus  to  its  use.  Geppert,^  however,  soon  made  it 
plain  that  Koch's  high  regard  for  bichlorid  of  mercury  was  partly  due 
to  an  overestimate  of  its  destroying  power,  inasmuch  as  the  thread  may 
carry  over  a  sufficient  amount  of  the  chemical  to  inhibit  growth.  Gep- 
pert  used  ammonium  sulphid  to  precipitate  the  mercury  and  thereby 
demonstrated  a  lower  figure  as  to  its  germicidal  power. 

Sternberg's  Method.* — As  early  as  1881  Sternberg  described  a 
method  that  is  evidently  the  precursor  of  the  "carbolic  coefficient"  and 
its  various  modifications.  He  mixed  5  c.  c.  of  a  young  culture  with 
equal  quantities  of  a  solution  of  the  germicidal  agent.  Thus  5  c.  c.  of 
a  1  to  200  solution  of  carbolic  acid  would  be  added  to  5  c.  c.  of  a  recent 

^Phil.  Trans,  of  the  Roy.  8oc.  of  London,  XLVI,  525. 

"Berl.  klin.  Wchnschr.,  1889,  XXVI,  789;  also  Deutsch.  med.  Wchnschr., 
1891,  XVII,  797. 

'"Mitteilungen  aus  dem  kaiser  lichen  Gesundheitsamte,"  I,  1881,  p.  324, 
abstracted  by  Whitelegge,  in  "Recent  Essays,"  New  Sydenham  Society,  London, 
1886,   CXV,  p.   493. 

*Bull.  of  Natl.  Bd.  of  Health,  U.  S.  A.,  1879.  I.  219,  227,  237  and  265, 
and  1881,  III,  23.     Sternberg's  "Manual  of  Bacteriology,"  N.  Y.,  1873,  p.  186. 


THE  STANDAEDIZATIOX  OF  DISINFECTANTS       1111 

culture  of  typhoid,  and  after  stated  intervals  1  or  3  loopfuls  would 
be  transferred  to  a  nutrient  medium. 

The  Gaenet  Method, — The  Garnet  method  proposed  by  Kronig  and 
Paul  ^  in  1897  was  an  attempt  at  a  more  precise  method.  Small  garnets 
of  uniform  size  are  coated  wdth  an  emulsion  containing  sporulating  an- 
thrax bacilli.  These  are  dried  and  then  dropped  into  the  disinfecting 
solution.  After  exposure  for  stated  intervals  the  garnets  are  removed, 
rinsed,  and  the  organisms  washed  off  in  sterile  water,  plated,  and  counted. 
Kronig  and  Paul  emphasized  the  necessity  of  the  disinfectant  reaching 
each  organism,  the  subsequent  washing  of  the  disinfectant  from  each 
organism,  and  the  performance  of  the  test  with  a  constant  number  of 
organisms,  since  the  time  required  for  disinfection  is  dependent  upon 
the  number  of  microorganisms  present.  This  method,  along  with  the 
thread  method  of  Koch,  has  been  supplanted  by  the  "carbolic  coefficient" 
of  Eideal  and  Walker  and  modifications  thereof. 

Carbolic  Coefficient. — 'Eideal  and  Walker  ^  in  1903  introduced  a 
method  by  which  they  proposed  to  determine  and  state  in  definite  numer- 
ical terms  the  value  of  any  disinfectant.  This  they  called  the  "carbolic 
coefficient,"  for  the  reason  that  carbolic  acid  is  taken  as  the  unit  of 
measurement  against  which  the  germicidal  power  of  all  other  siibstances 
is  compared.  It  is  often  spoken  of  as  the  "Eideal- Walker"  method  or 
the  "drop"  method,  because  one  drop  of  the  culture  of  B.  typhosus  was 
used  for  each  c.  c.  of  disinfectant  tested. 

Eideal  and  Walker  opened  a  new  era  in  the  standardization  of  dis- 
infectants. They  prepared  a  number  of  standard  conditions  for  the 
test,  without  which  comparable  results  are  not  possible.  The  most  im- 
portant conditions  are  temperature,  media,  nature  and  age  of  the  test 
microorganisms,  time  of  exposure,  degree  of  dilution,  etc.  The  Lancet 
Commission  ^  in  1908  recommended  several  modifications  of  the  Eideal- 
Walker  technic  and  this  method  was  further  modified  by  Anderson  and 
McClintic  *  who,  in  1911,  proposed  certain  changes  in  technic,  and  a  dif- 
ferent method  of  calculating  the  coefficient,  which  they  termed  the 
"phenol  coefficient." 

Kendall  and  Edwards  ^  in  1911  called  in  use  an  infected  agar  plug, 
designed  to  establish  the  penetrating  power  of  a  disinfectant. 

Physical-Chemical  Methods. — It  remains  to  cite  the  admirable 

*  "Die  chemischen  Grundlagen  der  Lehre  von  der  Giftwirkung  und  Disin- 
fektion,"  Zeit.  f.  Hyg.,  Leipzig,  1897,  XXV,  1. 

^  "The  Standardization  of  Disinfectants,"  Jour,  of  Boy.  San.  Inst.,  1903, 
XXIV,  424;  also  Jour,  of  Infect.  Dis.,  1912,  X,  254,  and  Am.  Jour.  Pub.  Health, 
913,  III,  575. 

^"The  Standardization  of  Disinfectants,"  Lancet,  1909,  II,  1454,  1516,  and 
1612. 

*Hyg.  Lab.  Bull.,  P.  H.  &  M.  H.  S.,  No.  82. 

^Jour.  of  Infect.  Dis.,  1911,  VIII,  250. 


1113  UISINFECTTOX 

work  of  Chick  and  Martin  '  ii|)()ii  the  laws  of  disinfection.  'I'hcy  pro- 
posed in  1908  that  the  time  element  be  established  arbitrarily  and  with 
this  called  for  two  other  constants,  namely,  the  number  of  bacteria  initi- 
ally present,  and  the  temperature.  It  was  shown  that  the  killing  of 
bacteria  stimulates  a  monomolecular  reaction  in  which  the  bacteria  take 
the  place  of  one  of  the  reacting  substances.  Phelps  ^  in  1911  made  the 
interesting  proposal  to  determine  the  germicidal  value  of  a  disinfectant 
at  any  temperature  and  concentration  by  a  mathematical  formula  which 
would  use  the  findings  of  a  single  experiment  of  comparatively  easy 
technic. 

Carbolic  Coefficient  Method. — This  test,  sometimes  known  as  the 
Eideal-Walker  method  of  standardizing  disinfectants,  has  been  vari- 
ously modified  and  improved.^  As  modified  it  is  at  present  the  best 
method  we  have  for  comparing  the  strengths  of  germicidal  substances  in 
solution  or  suspension.  The  method,  however,  has  distinct  limitations, 
as  it  only  gives  information  concerning  the  relative  value  of  germicides 
upon  the  naked  germ  cells  under  favorable  conditions  of  action. 

In  order  to  obtain  results  that  may  have  comparative  value  and  to 
avoid  discrepancies  it  is  of  the  greatest  importance  to  keep  all  the  factors 
of  the  test  uniform  and  to  give  attention  to  every  detail.  The  following 
are  the  more  important  factors  and  principles  upon  which  this  test  is 
based : 

Time. — The  time  is  taken  as  the  constant  and  the  strength  of  the 
disinfectant  as  the  variant.  It  is  easy  to  demonstrate  that,  if  reversed, 
totally  erroneous  results  will  be  obtained. 

Test  Organism. — ^The  coefficient  will  vary  with  different  microorgan- 
isms. The  culture  recommended  is  a  24-hour-old  B.  typhosus  grown  in 
bouillon.  It  is  important  always  to  use  the  same  strain  of  typhoid,  as 
different  races  vary  in  resistance.  Further,  the  culture  should  be  car- 
ried over  every  twenty-four  hours  on  at  least  three  preferably  seven  suc- 
cessive days  before  using  it  in  a  test.  It  is  advisable  to  filter  the  culture 
through  filter-paper  in  order  to  remove  clumps  just  before  beginning  a 
test.  The  culture  should  always  be  grown  under  the  same  conditions, 
upon  the  same  medium,  so  as  to  insure  uniformity. 

Medium. — The  standard  beef -extract  broth  (reaction  -f-  1-0)  recom- 

^  Chick,  Harriet:  Jour,  of  Hyg.,  1911,  VIII,  132;  also  Chick  and  Martin, 
Jour,  of  Hyg.,  1908,  VIII,  644,  698. 

■'Jour,  of  Infect.  Dis.,  1911,  VIII,  27. 

'  Rideal,  S.,  and  Walker,  J.  S.  A. :  Jour.  Roy.  San.  Inst.,  London,  1903,  Vol. 
XXIV,  p.  424.  "The  Standardization  of  Disinfectants,"  The  Lancet  Commission, 
Vol.  CLXXVII,  Nos.  4498,  4499,  4500.  Anderson  and  McClintic:  Jour.  Infect. 
Dis.,  Vol.  VIII,  No.   1,  Jan.,   1911,  pp.   1-26. 

The  carbolic  coefficient  above  described  is  not  the  Rideal-Walker  Technic 
but  modified  in  part  from  the  Hygienic  Laboratory  Phenol  Coefficient,  and  in 
part  from  the  Lancet  Commission  Method. 


THE  STANDAKDIZATION  OF  DISINFECTANTS       1113 

mended  by  the  Committee  on  Standards  of  the  American  Public  Health 
Association  for  Water  Analysis,  is  used  both  to  grow  the  test  typhoid 
organism  and  also  for  the  sub-cultures  made  after  exposure  to  the  dis- 


FiG.  154. — Device  for  Determining  Carbolic  Coefficients.  Consists  of  a  wooden 
box  14"  long  by  14"  wide  by  15"  high,  containing  a  metal  pail  (A)  10"  in  diameter, 
and  8X"  deep.  A  shelf  made  of  wire  mesh  (B)  is  inserted  2"  from  the  top  of  the  pail, 
which  is  filled  with  water.  A  pipe  with  a  faucet  (C)  from  the  bottom  of  the  pail  will 
be  found  very  convenient  to  draw  off  the  water  and  regulate  its  temperature.  Asbes- 
tos packing  (E)  completely  surrounds  the  pail  in  order  to  insulate  it.  The  lid  of  the 
box  (F),  which  is  raised  in  the  drawing,  contains  openings  for  the  five  test-tubes,  and 
three  other  openings  for  cultures  and  thermometer.  When  the  lid  is  in  place  the  test- 
tubes  rest  upon  the  shelf  (B).  A  drawer  (D)  in  the  bottom  of  the  box  is  convenient 
to  keep  test-tubes,  inoculating  needles,  thermometer,  and  other  parts  of  the  apparatus. 


infectant.  Ten  c.  c.  of  this  broth  are  placed  in  each  test-tube  for  the 
sub-cultures,  as  this  amount  is  sufficient  to  avoid  any  antiseptic  activity 
of  the  disinfectant  carried  over. 

Phenol,  first  proposed  by  Eideal  and  Walker,  and  now  adopted  by 
common  consent,  is  the  standard  of  comparison.     Phenol  may  readily 


1114  DISINFECTION 

be  obtained  chemically  ])ure,  and  exact  solutions  may  be  prepared  by 
titration  with  bromin.  A  stock  solution  of  5  per  cent,  is  usually  made 
and  this  is  diluted  for  the  purposes  of  the  test.  Another  advantage  of 
phenol  is  that  it  is  relatively  unaffected  by  the  presence  of  organic 
matter.    Only  formalin  perhaps  is  superior  to  it  in  this  regard. 

Temperature  of  Exposure. — This  is  one  of  the  most  important  fac- 
tors. The  germicidal  activity  of  substances  increases  vi^ith  the  tempera- 
ture. In  this  respect  germicidal  reactions  resemble  chemical  reactions. 
It  is  therefore  of  the  utmost  importance  that  the  solutions  tested  should 
be  always  at  the  same  temperature,  and  for  this  purpose  20°  C.  has  been 
selected  as  most  convenient.  The  solutions  to  be  tested  and  the  typhoid 
culture  itself  must  be  brought  to  this  temperature  before  they  are  mixed, 
and  then  maintained  at  this  temperature  in  a  water-bath. 

Proportion  of  Culture  to  Disinfectant. — Eideal  and  Walker  first  pro- 
posed to  use  one  drop  of  the  typhoid  culture  to  each  cubic  centimeter  of 
germicidal  solution.  It  is  more  accurate  to  use  a  measured  amount,  say 
0.1  c.  c.  of  the  24-hour-old  bouillon  culture  of  typhoid  to  5  c.  c.  of  solu- 
tion. These  are  convenient  amounts  easily  and  accurately  measured  with 
standardized  delivery  pipettes.  It  should  be  kept  in  mind  that  the  addi- 
tion of  the  bouillon  culture  dilutes  the  germicidal  solutions,  but  as  this 
is  a  constant  factor  it  does  not  affect  the  comparative  values  as  expressed 
by  the  carbolic  coefficient,  but  may  be  taken  into  consideration  in  judg- 
ing the  germicidal  values  for  practical  work. 

Inoculation  Loops. — Precisely  the  same  quantity  of  fluid  from  the 
mixture  should  be  removed  each  time  for 'the  transplants.  This  is  done 
most  readily  with  platinum  loops  made  of  23  U.  S.  standard  gage  wire 
and  a  loop  4  millimeters  in  diameter  inside  measurement.  This  may  be 
made  over  a  No.  14  wire  U.  S.  gage.  Several  of  these  loops  should  be 
on  hand.  They  are  sterilized  and  placed  upon  a  rack.  As  one  is  used 
it  is  flamed  and  returned  to  the  rack,  so  that  it  will  be  cool  when  taken 
in  its  turn. 

Dilutions. — A  standard  series  of  dilutions  should  be  made  of  the 
phenol  standard  and  also  of  the  germicide  to  be  tested — in  accordance 
with  the  tables  in  Hygienic  Laboratory  Bulletin  No.  82. 

Technic. — The  following  method  is  the  one  used  in  my  laboratory  for 
carrying  out  the  carbolic  coefficient : 

A  solution  of  5  per  cent,  phenol  c.  p.  is  made  and  standardized  chem- 
ically.* The  usual  dilutions  of  1  to  90,  1  to  100,  and  1  to  110,  etc.,  are 
made  from  this  stock  solution  as  desired. 

The  solutions  of  the  germicidal  substances  to  be  tested  must  be  made 
accurately,  according  to  volumetric  or  gravimetric  methods. 

The  tests  are  carried  out  in  test-tubes  one  inch  in  diameter  and  three 
inches  long.    These  are  placed  in  a  row  in  a  water-bath.     The  test-tubes 

*By  bromin  titration.     (See  description  in  Sutton's  "Volumetric  Analysis.") 


THE  STANDARDIZATION  OF  DISINFECTANTS       1115 

rest  upon  a  bed  of  sand  and  are  held  in  place  by  a  wire  rack  or  simply 
by  a  board  perforated  with  holes  of  suitable  size.  If  the  water-bath  is 
sufficiently  large  and  the  water  brought  to  Just  20°  C.  it  may  be  main- 
tained at  this  temperature  with  but  slight  attention. 

Each  test-tube  receives  5  c.  c.  of  the  solution  to  be  tested.  Time  is" 
allowed  for  the  solutions  to  reach  the  temperature  of  20°  C,  then  the 
culture  which  has  previously  been  brought  to  20°  C.  is  added  and  mixed 
with  the  solution  in  each  test  tube  in  turn.  The  culture  is  added  to 
each  tube  at  intervals  of  just  30  seconds.  With  a  row  of  five  tubes  this 
will  make  a  2y2-minute  interval  for  each  tube  as  the  subsequent  sub-in- 
oculations are  made. 

Two  and  one-half  minutes  after  the  phenol  and  the  culture  have 


0  minute 


1/$  minute 


1  minute 


\}/2  minutes 


2  minutes 


^z:^. 


c:5 


5  c.c.  phenol  1:90      5  c.c.  ph«K,l  1: 100      ^5  c^c.  solution  x        O.S^c^c^  solution  x      0.5  c^c^  solution  x 
0.1  c.c.rire  O.l  c.c.  culture  ^  and  ;^_  and^^^  ^^  c.c.  cuUure 


Arrangement  of  Tubes  in  Water-bath  and  Their  Contents. 


been  mixed  together  in  tube  No.  1  a  loopful  of  the  mixture  is  removed 
and  planted  in  broth ;  30  seconds  later  a  loopful  of  the  mixture  is  taken 
from  tube  No.  2,  and  so  on  throughout  the.  series  at  intervals  of  30 
seconds.  The  entire  procedure  of  removing  the  loopful  of  mixture  and 
planting  it  into  one  of  the  test-tubes  containing  10  c.  c.  of  broth  requires 
only  about  15  seconds,  allowing  plenty  of  time  to  flame  the  loop,  replace 
it  in  the  rack,  and  pick  up  another  loop  which  had  previously  been  flamed 
and  has  cooled  sufficiently  for  the  next  operation.  The  test-tubes  hold- 
ing the  mixture  of  germicidal  solution  and  culture  need  not  be  removed 
from  the  water-bath,  and  it  is  not  necessary  to  keep  them  plugged  with 
cotton.  The  loop  should  always  be  plunged  to  the  bottom  and  care  taken 
not  to  touch  the  sides  of  the  test-tube  and  always  to  carry  away  a  loopful 
of  the  fluid  to  be  transplanted.  The  test-tubes  holding  the  medium  for 
the  transplants  are  conveniently  placed  in  wooden  racks  and  are  incu- 
bated at  37°  C.  for  forty-eight  hours,  when  the  readings  as  to  growth 
(  +  )  or  no  growth  ( — )  are  tabulated. 


1116  DISINFECTION 

An  example  of  a  carbolic  cocdicicnt  icst  follows 


2>^ 
Minutes 

5 

Minutes 

Minutes 

10 
Minutes 

12J^ 
Minutes 

Phenol             1 

90 

+ 

+ 
+ 

+ 

— 

+ 

Phenol             1 

100 

Solution  X      1 

900 

+                  — 

+         1         4- 

Solution  X      1 

1,000 

Solution  X      1 

1,200 

4- 

The  carbolic  coefficient  of  solution  X  is  therefore  VVu"  =  10. 

The  carbolic  coefficient  is  determined  by  comparing  the  strengths 
of  the  unknown  disinfectant  with  phenol  that  "show  life"  in  the  21/^  and 
5  minute  periods — or  practically  the  strengths  that  kill  in  7  minutes. 
Previously  it  was  permissible  to  compute  the  coefficient  upon  any  of  the 
periods  of  the  test  up  to  30  minutes.  However,  it  was  found  possible  in 
this  way,  either  by  chance  or  intent,  to  obtain  an  extravagantly  high  co- 
efficient. Thus  Chick  and  Martin  showed  that  the  phenol  coefficient  of 
certain  metallic  salts  varies  from  13.8  to  550,  depending  on  whether  the 
period  of  comparison  is  2i^  or  30  minutes. 

Anderson  and  McClintic  ^  have  modified  the  procedure  employed  by 
the  Lancet  Commission  to  determine  the  coefficient  to  be  the  mean 
between  the  strength  and  the  time  coefficient;  that  is,  the  figure  repre- 
senting the  degree  of  dilution  of  the  weakest  strength  of  the  disinfectant 
that  kills  within  2%  minutes  is  divided  by  the  figure  representing  the 
degree  of  dilution  of  the  weakest  strength  of  the  phenol  control  that 
kills  within  the  same  time.  The  same  calculation  is  done  for  the  weakest 
strength  that  kills  in  15  minutes.    The  mean  of  the  two  is  the  coefficient. 

On  page  1117  is  an  example  of  the  "phenol  coefficient"  as  determined 
by  the  Hygiene  Laboratory  method. 

Kendall  and  Edwards  ^  have  devised  an  ingenious  method  to  deter- 
mine the  penetrating  power  of  germicides  in  the  presence  of  organic 
matter.  The  method  consists  essentially  of  cylindrical  moulds  of  agar 
impregnated  with  the  test  organism.  Sections  of  these  cylindrical  moulds 
or  "artificial  feces"  are  exposed  to  the  germicide  solutions  and  plants 
made  after  proper  intervals  of  time  from  a  core  taken  from  the  center  of 
the  cylinder. 

Interpretation  of  Eesults. — A  low  carbolic  coefficient  usually 
means  a  useless  disinfectant.  Formalin  has  a  low  coefficient,  although 
formaldehyd  is  one  of  our  potent  and  serviceable  germicides.  The  reason 
for  this  discrepancy  consists  in  the  fact  that  the  coefficient  is  based  upon 
formalin  which  contains  only  40  per  cent,  or  less  of  formaldehyd.  On 
the  other  hand  it  should  be  remembered  that  because  a  germicide  has  a 

^Hygienic  Laboratory  Bulletin,,  U.  S.  P.  H.  and  M.  H.  S.,  No.  82,  1912. 
""Jour.  Infect.  Dis.,  Vol.  VIII,  No.  2,  March,   1911,  pp.  250-257. 


THE  STANDARDIZATION  OF  DISINFECTANTS       1117 
PHENOL  COEFFICIENT:  HYGIENIC  LABORATORY  METHOD 


Time  Culture  Exposed  to  Action  of 

Disinfectant  for  Minutes 

Phenol 

Sample 

Dilution 

CoeiBcient 

2J^ 

5 

7M 

10 

10 

15 

Phenol 

1:  80 

375    ,    650 

1:90 

+ 







1:  100 

-)- 

+ 

+ 

— 

— 

— 

80          110 

1:  110 

+ 

+ 

+ 

+ 

+ 

— 



2 

Disinfectant  "A" 

1:350 

_ 

4.69  +  5.91 

1:375 

— 

— 

— 

2 

1:400 

+ 

— 

— 

— 

1:425 

-+ 

+ 

— 

— 

— 

— 

5.30 

1:450 

+ 

+ 

— 

— 

— 

— 

1:500 

+ 

+ 

— 

— 

— 

— 

1:550 

+ 

+ 

+ 

— 

— 

— 

1:600 

+ 

+ 

+ 

+ 

— 

— 

1:650 

+ 

+ 

+ 

+ 

+ 

— 

1:700 

+ 

+ 

+ 

+ 

+ 

+ 

1:750 

+ 

+ 

+ 

+ 

+ 

+ 

Temperature  of  medication,  20°  C. 

Culture  used,  B.  typhosus,  24-hour,  extract  broth  filtered. 

Proportion  of  culture  and  disinfectant,  0. 1  c.  c.  +  5  c.  c. 

high  coefficient  is  no  true  indication  that  it  is  a  favorable  agent  in  prac- 
tical work.  There  are  many  factors  still  to  be  considered.  Thus  a  use- 
ful disinfectant  should  not  be  very  poisonous  to  higher  animals;  should 
not  corrode  metals  or  rot  fabrics;  should  not  stain  or  bleach;  should 
not  have  an  unpleasant  smell;  should  be  reasonably  cheap;  should  be 
readily  miscible  with  water  and  not  deposit  from  solution  or  suspension ; 
should  be  reasonably  stable ;  should  act  both  in  alkaline  and  acid  media ; 
should  not  be  greatly  influenced  by  the  presence  of  organic  matter,  and 
should  possess  a  fair  power  of  penetration.  It  must  at  once  be  evident 
that  no  one  test  can  determine  all  of  these  factors,  so  that  a  thorough 
and  comprehensive  study  of  the  substance  to  be  used  should  be  made  upon 
many  different  parasites  under  many  different  conditions  before  we  can 
have  a  satisfactory  knowledge  of  its  power  and  limitations.  This  is  one 
of  the  reasons  that  makes  us  conservative  about  taking  up  new  germicidal 
substances  until  thoroughly  tested  under  difl^erent  conditions,  and  in- 
clines us  to  adhere  to  well-known  chemicals  such  as  bichlorid  of  mercury, 
carbolic  acid,  the  coal-tar  creosotes,  lime,  the  hypochlorites,  and  formalin, 
the  advantages  and  limitations  of  which  have  been  thoroughly  established. 


1118 


DISINFECTION 


The  Phenol  Coefficient  of  Some  Commercial  Germicides 
Determined  by  Thomas  B.  McClintic^ 


Bacterol 

Benetol 

Cabot's  Sulpho-Napthol 

Carbolene 

Carbolozone 

Car-Sul 

Chloro-Naptholeum 

Cremoline 

Creo-Carboline 

Creolin-Pearson • 

Cresoleum 

Crude  Carbolic  Acid 

Dusenberry's  Liquid  Creoleum 

Germol 

Hycol 

Hygeno  A 

Kreosota 

Kreotas 

Kreso 

Kresolig 

Lincoln  Disinfectant 

Liquor  cresolis  compositus  (U.  S.  P.) 

Lysol 

"Napthalene  Disinfectant" 

Phenoco 

Phenol  Uquid  (U.  S.  P.,  1890) 

Phenosote 

Phinotas 

R.  R.  Rogers  Disinfectant 

Rudisch's  Creolol 

Saponified  Cresol 

Tarola 

Trikresol 

Zenoleum • 

Zodone 

Zonol 

Antozone  ^ 

Creola  Disinfectant 

Dioxygen 

Electrozone 

Formacone  Liquid 

Killitol 

Kretol 

Listerine 

Phenol  Disinfectant  and  Cleansing  Liquid 

Phenol  Sodique 

Pino-lyptol 

Piatt's  Chlorides 

Pubhc  Health  Liquid  Disinfectant 

Sanitas 

The  Twentieth  Century  Disinfectant 

Veroform  Germicide 

Worrell's  Insect  Exterminator  and  Disinfectant 
Zodane  No.  3 


Without  Or- 
ganic Matter 

With  Organic 
Matter 

1.58 
1.23 
3.87 
1.36 
1.48 
2.00 
6.06 
1.26 
4.03 
3.25 
2.90 
2.75 
1.00 
2.12 

12.30 
3.56 
1.26 
1.10 
3.92 
2.18 
1.48 
3.00 
2.12 
2.50 

15.00 
1.77 
3.43 
1.37 
3.03 
1.24 
1.03 
3.12 
2.62 
2.25 
1.62 
2.37 
nU 
0.52 
weak 
0.90 
weak 
weak 
0.92 
weak 
0.61 
weak 
0.27 
weak 
0.48 
0.30 
0.13 
0.43 
weak 
weak 

1.34 

0.92 

2.33 

0.65 

0.48 

1.75 

3.21 

0.69 

2.26 

2.52 

1.75 

2.63 

0.40 

1.79 

9.37 

1.81 

0.65 

0.30 

2.32 

1.48 

1.10 

1.87 
1.57 

1.36 

9.86 

1.76 

2.31 

0.53 

2.05 

0.75 

0.57 

1.93 

2.50 

1.64 

0.51 

1.57 

»  Hyg.  Lab.  Bull.  No.  82,  U.  S.  P.  H.  &  M.  H.  S. 
=  The  following  disinfectants  have  a  coefficient  of  less  than  1 
was  impracticable  to  determine  the  coefficient. 


Most  of  them  are  so  weak  that  it 


CHAPTEE  II 

PHYSICAL  AGENTS    OF   DISINFECTION 

Sunlight. — Sunlight  is  an  active  germicide.  It  destroys  spores  as 
well  as  bacteria.  Unfortunately,  the  sunlight  is  so  uncertain  and  the 
force  of  the  sun's  rays  so  variable  and  their  disinfecting  powers  so  super- 
ficial that  it  cannot  be  depended  upon  as  an  aggressive  measure  in  attack- 
ing infection.  In  rooms,  ships,  and  confined  spaces  sunshine  comes 
more  under  the  purview  of  the  sanitarian  than  under  that  of  the  disin- 
fector^  but  the  latter  can  always  use  it  to  advantage  in  supplementing 
his  other  methods.  Eoom  and  objects  may  always  be  sunned  and  aired 
with  advantage  after  disinfection. 

The  different  rays  of  light  have  very  different  effect  upon  germ  life. 
The  blue-violet  and  ultraviolets,  that  is,  the  more  refragible  chemical 
rays  of  short  wave  length,  are  the  only  ones  possessing  germicidal  power. 
The  red  and  yellow  rays  are  practically  inert  in  this  regard.  The  source 
of  light  seems  to  have  little  influence  upon  the  result ;  it  is  more  a  ques- 
tion of  intensity  and  nature  of  the  rays.  Even  diffused  light  retards 
growth  and  development  of  microorganisms,  and  if  strong  enough  will 
finally  kill  them.  Electric  light  containing  the  proper  rays  is  efficient. 
The  Eontgen  rays  have  no  bactericidal  properties.  The  sun  is  the  nat- 
ural generator  of  ultraviolet  rays. 

The  time  required  for  light  to  destroy  bacteria  varies  with  its  bright- 
ness and  with  conditions  such  as  moisture,  temperature,  transparency, 
and  composition  of  the  media,  which  aid  or  hinder  the  effect  of  the 
rays.  The  time  also  varies  with  the  different  microorganisms;  plague 
bacilli  and  cholera  vibrio  usually  die  more  quickly  than  tubercle  bacilli. 
Spores  are  much  more  resistant  to  the  influence  of  the  chemical  rays 
than  the  bacterial  cells  themselves.  Thus  it  usually  requires  about 
thirty  hours'  sunning  to  kill  an  anthrax  spore,  while  the  anthrax  ba- 
cillus is  killed  in  one  or  two  hours  when  subjected  to  the  same  con- 
ditions. 

Ultraviolet  Rays. — Ultraviolet  rays  are  invisible  rays  which  lie  beyond 
the  violet  end  of  the  spectrum.  In  general  it  may  be  said  that  they  in- 
clude those  rays  of  short  wave  lengths  between  2,900  and  2,250  Ang- 
strom.^ 

The  wave  lengths  of  the  visible  spectrum  are  from  about  7,610  Ang- 

*One  Angstrom  unit  is  1/10,000,000  of  a  centimeter. 

1119 


1120  PHYSICAL  AGEXTS  OF  DISINFECTION 

strom  units  (red)  to  about  3,970  (violet).  According  to  Nogier  ^  the 
ordinary  ultraviolet  rays  extend  from  3,920-3,000  units,  the  average 
rays  from  3,000-2,200,  and  the  extreme  ultraviolet  rays  from  2,200-1,000 
units.  He  states  that  rays  from  3,920-3,000  are  not  bactericidal  to  any 
extent  but  produce  sunburn  after  long  exposure.  Eays  between  3,000- 
2,200  have  a  strong  action  on  bacteria  while  those  from  2,200-1,000  are 
still  more  powerful  but  are  of  little  value  since  they  are  easily  absorbed 
by  air  and  other  substances. 

Ultraviolet  rays  from  the  Cooper  Hewitt  lamp,  produced  by  an  elec- 
tric discharge  through  mercury  vapor  contained  in  a  quartz  lamp  in 
vacuo,  have  an  exceedingly  powerful  germicidal  action,  killing  spores  as 
well  as  bacterial  cells.  Glass  is  opaque  to  these  rays  of  short  wave  lengths 
and  it  is  therefore  necessary  to  use  quartz  globes. 

Cernovodeanu  and  Henri  ^  have  shown  that  the  action  of  ultraviolet 
light  is  greater  near  the  lamp  and  decreases  as  the  distance  increases 
from  the  source  of  the  rays.  Ultraviolet  rays  act  just  as  quickly  at  0° 
C.  as  at  55°  C.  They  also  act  equally  quickly  in  the  presence  or  absence 
of  oxygen.  Pure  cultures  of  non-spore-bearing  microorganisms  are 
killed  in  from  5  to  60  seconds.  Molds,  however,  are  only  partially  de- 
stroyed. 

Ultraviolet  light  does  not  act  indirectly  through  production  of  hydro- 
gen peroxid  or  ozone,  but  kills  bacteria  by  some  direct  action  upon  the 
protein  which  it  seems  to  coagulate  and  decompose. 

On  the  whole,  very  satisfactory  results  have  been  obtained  in  disin- 
fecting water  when  clear  water  is  exposed  to  the  rays,  and  in  several 
cities  in  France  and  elsewhere  the  municipal  water  supply  is  treated  by 
this  process.     (See  pages  705  and  910.) 

Proteins  and  other  bodies  of  high  molecular  weight  interfere  with  the 
action  of  the  rays.  Turbidity,  both  organic  and  inorganic,  has  a  similar 
action.  Color,  within  certain  limits,  seems  to  have  no  influence  whatso- 
ever. 

Ultraviolet  rays  cannot  be  used  successfully  to  pasteurize  milk  for 
the  reason  that  milk  is  opaque,  and  furthermore  the  rays  act  upon  the 
protein,  causing  unpleasant  odors  and  tastes  to  develop.  Attempts  to  kill 
the  bacteria  in  turbid  water,  beer,  wine,  and  vinegar  have  been  only  par- 
tially successful,  because  the  organic  matter  interferes  with  the  action 
and  penetration  of  the  rays. 

Ultraviolet  light  possesses  no  therapeutic  value  so  far  as  direct  de- 
struction of  bacteria  within  any  of  the  tissues  of  the  body  is  concerned. 

*Nogier,  T. :  "Les  Rayons  ultraviolets  et  leur  application  h  la  sterilisation 
des  liquides,"  Rev.  d'Hyg.  et  de  Police  Sanit.,  T,  32,  1910,  pp.  421-431. 

^  Cernovodeanu,  P.,  et  Henri,  Victor :  "Etude  de  I'actioii  des  rayons  ultra- 
violets sur  les  microbes,"  Compt.  rend.  hebd.  de  Seanc.  d.  I'Acad.  des  Scienc, 
T.  150,  1910,  pp.  52-54. 


PHYSICAL  AGENTS  OF  DISIXFECTION  1121 

VerlioefE^  has  shown  that  ultraviolet  light  will  not  destroy  bacteria 
within  the  cornea,  even  Avhcn  the  latter  is  perfectly  transparent,  with- 
out at  the  same  time  severely  injuring  the  corneal  tissues. 

Electricity.- — It  appears  that  electric  currents  have  little  germicidal 
action  in  themselves  and  that  the  apparent  effects  noted  by  some  investi- 
gators are  due  either  to  the  heat  generated  by  the  current  or  to  elec- 
trolytic action.  Electricity  has  very  little  use  in  practice  as  a  disin- 
fectant. Hermite  used  the  products  of  electrolysis  for  the  sterilization 
of  sewage.  He  added  sea-water  to  the  sewage  and  the  electrolytic  action 
caused  the  formation  of  hypochlorite,  which  has  well-known  germicidal 
action.  The  effect  of  electrical  currents  upon  bacteria  seems  to  be  a 
purely  chemical  one  in  the  case  of  antiseptic  substances  being  formed  by 
electrolytic  decomposition ;  or  a  thermal  one  in  the  case  of  the  production 
of  heat,  which  so  frequently  attends  the  discharge  of  electric  currents. 

Burning. — Fire  is  the  great  purifier.  Burning  has,  however,  a  very 
limited  range  of  usefulness  in  practical  disinfection.  The  disinfector 
is  seldom  Justified  in  burning  an  article  against  the  wish  of  its  owner, 
for  we  now  possess  methods  by  which  any  object  may  be  rendered  safe 
so  far  as  its  power  of  conveying  disease  is  concerned.  In  actual  prac- 
tice, however,  the  disinfector  often  comes  across  a  great  amount  of  rub- 
bish and  articles  of  little  value  that  he  will  find  safer  and  cheaper  to 
burn  than  to  disinfect.  The  burning  of  garbage  and  refuse  is  the  safest 
means  of  disposing  of  such  organic  substances  from  a  sanitary  stand- 
point, especially  in  districts  where  pestilential  disease  prevails.  From 
the  same  standpoint  the  cremation  of  all  bodies  dead  of  a  communicable 
disease  is  the  safest  method  of  preventing  possible  spread  of  infection 
from  this  source.  Burning  is  the  most  satisfactory  method  of  disinfect- 
ing and  disposing  of  small  amounts  of  sputum  and  other  infected  dis- 
charges. Burning  of  the  surface  of  the  ground  by  means  of  gasoline 
torches  and  petroleum  is  sometimes  used  to  destroy  animal  parasites  and 
other  infections  which  find  lodgment  on  the  soil.  The  gasoline  torch  is 
also  used  to  fight  insect  pests  of  trees  and  plants. 

Dry  Heat. — A  temperature  of  150°  C.  continued  for  one  hour  will 
destroy  all  forms  of  life,  even  the  most  resistant  spores.  It  is  easy 
to  maintain  this  temperature  in  an  apparatus  of  special  construction 
known  as  a  hot-air  or, dry-wall  sterilizer.  Glassware  and  many  objects 
that  will  stand  this  degree  of  heat  are  sterilized  in  an  oven  of  this  kind 
in  bacteriological  laboratories  and  in  surgical  clinics.  Dry  heat  is  not 
as  satisfactory  a  disinfectant  as  moist  heat,  as  it  lacks  the  power  of  pene- 
tration and  is  injurious  to  fabrics.  ]\Iost  materials  will  bear  a  tempera- 
ture of  110°  C.  without  much  injury,  but  when  this  temperature  is  ex- 
ceeded signs  of  damage  soon  begin  to  show.     Scorching  occurs  sooner 

'Verhoeff,  F.  H.:  "Ultraviolet  Light  as  a  Germicidal  Agent,"  J.  A.  M.  A., 
March  7,  1914,  LXII,  10,  p.  762. 


1132  PHYSICAL  AGENTS  OF  DISIM'KCTION 

with  woolen  materials,  such  as  flannels  ajid  bJaiik(.'ls,  than  with  cotton 
and  linen.  Over-drying  renders  most  fabrics  vcj'y  lu'itllc,  Ijiit  this  injury 
may  be  lessened  by  allowing  the  materials  wliich  liave  hecn  suhje(;ted  to 
dry  heat  to  remain  in  the  air  long  enough  to  regain  their  natural  degree 
of  moisture  and  pliability  before  manipulating  them. 

The  ordinary  household  cooking  oven  is  as  good  as  any  specially 
contrived  apparatus  for  the  disinfection  of  small  objects  by  dry  heat. 
In  the  absence  of  a  thermometer  it  is  usual  to  heat  the  oven  to  a  point 
necessary  to  brown  cotton  and  expose  the  objects  no  less  than  one  hour. 

Boiling. — Boiling  is  such  a  commonplace,  every-day  procedure  that 
it  is  often  neglected  in  practical  disinfection  despite  the  fact  that  it 
is  one  of  the  readiest  and  most  etfective  methods  of  destroying  infections 
of  all  kinds.  An  exposure  to  boiling  water  at  100°  C.  continued  for  an 
hour  will  destroy  the  living  principles  of  practically  all  the  infectious 
diseases  with  which  we  have  to  deal  in  public  health  work.  To  be  sure, 
there  are  a  few  spores  that  have  shown  a  remarkable  resistance  to  boiling 
water  and  streaming  steam  in  laboratory  experiments.  Boiling,  there- 
fore, cannot  be  entirely  depended  upon  where  tetanus,  anthrax,  or  re- 
sisting spores  are  in  question.  As  a  matter  of  fact,  a  degree  of  moist 
heat  much  lower  than  the  boiling  point  of  water  is  effective  against  the 
great  majority  of  the  known  viruses.  Tlius  a  temperature  of  60°  C. 
for  20  minutes  will  destroy  the  microorganisms  of  cholera,  typhoid,  dys- 
entery, diphtheria,  plague,  tuberculosis,  pneumonia,  erysipelas,  and  prac- 
tically all  non-spore-bearing  bacteria.    Boiling  kills  them  at  once. 

Boiling  is  especially  applicable  to  the  disinfection  of  bedding,  body 
linen,  towels,  and  fabrics  of  many  kinds;  also  kitchen  and  tableware, 
cuspidors,  urinals,  and  a  great  variety  of  objects.  Surfaces,  such  as 
floors,  walls,  beds,  metal  work,  etc.,  may  be  efi^ectively  disinfected  by 
mechanically  cleansing  them  with  boiling  water.  The  efficacy  of  boiling 
water,  especially  when  used  in  such  circumstances,  is  greatly  increased 
by  the  addition  of  corrosive  sublimate,  carbolic  acid,  or  one  of  the  alka- 
line coal-tar  creosotes.  The  addition  of  lye,  borax,  or  a  strong  alkaline 
soap  also  increases  the  penetrating  and  detergent  power  of  boiling  water 
when  applied  to  surfaces  soiled  with  organic  or  oily  matters. 

In  using  boiling  water  for  the  disinfection  of  bright  steel  objects 
or  cutting  instruments  the  addition  of  1  per  cent,  of  an  alkaline  sub- 
stance such  as  carbonate  of  soda  will  prevent  rusting  and  injury  to  the 
cutting  edge. 

Steam. — Steam  is  one  of  the  most  satisfactory  disinfecting  agents  we 
possess.  It  is  reliable,  quick,  and  may  be  depended  upon  to  penetrate 
deeply.  Further,  it  does  more  than  disinfect;  it  sterilizes.  Vegetating 
bacteria  are  killed  instantly  and  most  spores  in  a  few  minutes.  It  may 
therefore  be  used  to  destroy  the  infection  of  any  of  the  communicable 
diseases. 


PHYSICAL  AGENTS  OF  DISIITFECTION 


1123 


Either  streaming  steam  or  steam  vmder  pressure  is  used  in  practical 
disinfection. 

Streaming  steam  has  the  same  disinfecting  power  as  boiling  water, 
and  an  exposure  of  half  an  hour  to  an  hour  is  sufficient.  Steam  under 
pressure  is  a  more  powerful  germicide  than  streaming  steam.  At  a  pres- 
sure of  15  pounds  to  the  square  inch  steam  has  a  temperature  of  approxi- 
mately 120°  C.  and  may  be  depended  upon  to  sterilize  in  20  minutes. 
At  20  pounds  pressure  it  has  a  temperature  of  approximately  125°  C 
and  will  sterilize  in  15  minutes. 

Steam  is  applicable  to  the  disin- 
fection of  bedding,  clothing,  fabrics 
of  all  kinds,  and  a  great  variety  of 
other  objects,  provided  certain  pre- 
cautions are  taken  to  prevent  shrink- 
ing, staining,  running  of.  colors,  etc. 
Steam  shrinks  woolens  and  injures 
silk  fabrics;  it  ruins  leather,  fur, 
skins  of  all  kinds,  rubber  shoes,  oil- 
cloth, and  articles  made  of  impure 
rubber  or  containing  glue,  varnish, 
or  wood. 

It  is  important  in  disinfecting 
with  steam,  whether  with  streaming 
steam  or  steam  under  pressure,  to 
expel  the  air  from  the  apparatus. 
The  air,  being  a  poor  conductor  of 
heat,  forms  dead  spaces  and  prevents 
the  steam's  coming  in  direct  contact 
with  the  articles  to  be  disinfected, 
thereby  defeating  the  object  to  be 
attained.     As  steam  is  lighter  than 

air  the  latter  can  best  be  expelled  from  the  apparatus  by  admitting 
the  steam  from  above,  in  which  case  the  descending  column  of  steam 
forces  the  air  out  at  the  bottom.  If  the  steam  is  admitted  at  the  bottom 
it  swirls  up,  making  a  nearly  uniform  mixture  with  the  air,  and  while 
the  temperature  quickly  rises  in  the  apparatus  the  air  escapes  mixed 
with  the  steam,  so  that  it  takes  a  long  time  and  an  unnecessary  waste  of 
steam  to  drive  out  the  contained  air. 

Disinfection  with  streaming  steam  may  be  accomplished  in  many 
ways  without  the  use  of  special  apparatus.  For  rough  and  ready  work 
on  the  railroad  the  objects  to  be  disinfected  may  be  hung  in  a  freight- 
car  and  the  steam  brought  from  the  locomotive.  On  board  a  vessel  one 
of  the  compartments  above  the  water-line  may  be  filled  with  steam 
from  the  boiler.     Objects  may  be  steamed  in  any  rough  structure  wher- 


FlQ. 


155. — Section  theough  Arnold 
Steam  Sterilizer. 


1124 


PHYSICAL  AGENTS  OF  DISINFECTION 


Fig.   156. — Section  through  Auto 

CLAVE. 


ever  a  boiler  is  founfl  to  furnish  the  steam.    Such  a  structure  need  not  be 

tight,  for  the  streaming  steam  escaping  from  the  cracks  produces  a  circu- 
lation and  favors  penetration. 

In  the  laboratory  small  objects  are 
disinfected  in  streaming  steam  in  the 
Arnold  steam  sterilizer  or  the  Koch 
steamer. 

On  account  of  the  great  certainty 
with  which  steam  under  pressure  acts 
it  is  the  favorite  method  in  practical 
disinfection,  especially  where  steriliza- 
tion is  required,  and  devices  for  ap- 
plying this  process  on  a  large  scale 
have  reached  a  high  degree  of  perfec- 
tion. The  smaller  forms  of  steam 
sterilizers  under  pressure  are  known  as 
digestors  or  autoclaves  and  the  larger 
ones  as  steam  disinfecting  chambers. 

The  Autoclave. — The  autoclave, 
digester,    or    steam    sterilizer    consists 

of  a  closed  kettle  usually  made  of  copper 

and    sufficiently    strong    to    withstand    the 

pressure.     Water  is  placed  in  the  kettle  and 

the  heat  is  applied  to  the  bottom,  usually 

by  means  of  several  Bunsen  gas  jets.     The 

apparatus    is    surrormded    as    high    as    the 

shoulder,  where  the  lid  is  attached,  with  a 

metal  jacket  which   serves   the  purpose   of 

bringing  the  heat  of  the  flame  in   contact 

with  the  entire  surface  of  the  kettle.     The 

lid  is  made  to  fit  tightly  by  means  of  screw 

bolts  and  a  rubber  gasket.     A  thermometer, 

pressure  gage,  safety  valve  and  a  small  open- 
ing with  a  stopcock  for  the  purpose  of  al- 
lowing the  escape  of  the  air  are  provided. 

If  all  the  air  is  not  expelled  from  the  ap- 
paratus the  dead  spaces  will  have   a  much 

lower  temperature  than  that  registered   on 

the  thermometer.      For  instance,  the  steam 

itself  may  register  a  temperature  of  130°  C, 

while  test  fluids  exposed  may  only  reach  70° 

to  80°  C.     Therefore,  in  using  this  form  of 

sterilizer  it  is  customary  to  allow  the  steam  to  escape  in  full  force  for 

several  minutes  before  permitting  the  pressure  to  rise. 


^m,M 


Fig.    157. — Bramhall-Deane 

Steam  Sterilizer. 


PHYSICAL  AGENTS  OF  DISINFECTION 


1125 


In  the  sterilization  of  liquids,  for  which  this  apparatus  is  frequently 
used,  it  is  important,  at  the  conclusion  of  the  process,  not  to  take  off 
the  lid  or  open  the  valves,  or  in  any  other  way  release  the  pressure  until 
the  apparatus  has  cooled ;  otherwise  the  condensed  steam  causes  a  dimin- 
ished pressure,  in  which  the  heated  liquids  will  boil  energetically,  resulting 
in  a  bubbling  over,  a  blowing  out  of  stoppers,  or  a  bursting  of  the  flasks. 
It  is  therefore  necessary  to  wait  until  the  pressure  is  zero,  as  registered 
on  the  gage;  or,  better,  until  the  condensing  steam  produces  a  partial 
vacuum  and  the  air  is  automatically  sucked  in  through  the  vacuum  valve, 


Fig.  158. — Cross  Section  through  Steam  Disinfecting  Chamber. 


which  is  sometimes  fitted  in  the  lid  of  the  apparatus  for  this  very  pur- 
pose. 

The  Steam  Chamber. — The  steam  disinfecting  chamber  has  reached 
a  high  degree  of  usefulness  through  the  gradual  perfection  of  the  details 
of  its  working  parts.  These  chambers  are  somewhat  complicated  and 
their  mechanical  construction  must  be  m_astered  in  order  to  insure  relia- 
ble results.  Steam  disinfecting  chambers  may  be  used  with  streaming 
steam  or  with  steam  under  pressure ;  with  formaldehyd  gas  alone,  or  with 
this  gas  in  combination  with  dry  heat;  and,  finally,  with  various  com- 
binations of  these  methods  with  or  without  a  vacuum. 

The  disinfecting  chamber  itself  may  be  rectangular  or  cylindrical 


112r;  PIIYSTC'VL  ACil'^X'l'S  OF   DISIXI'KC^riON 

in  shape,  the  former  giving  more  effective  space,  the  latter  being  a 
stronger  and  cheaper  method  of  construction.  The  chamber  is  built  of 
an  inner  and  outer  shell  forming  a  steam  jacket,  as  shown  in  Fig.  158. 
The  steam  jacket  serves  several  purposes.  By  heating  the  contents  of 
the  disinfecting  cylinder  before  the  steam  is  turned  in  it  avoids  condensa- 
tion. During  the  process  of  disinfection  it  helps  keep  the  steam  in  the 
chamber  "live/'  thereby  preventing  the  vi^etting  of  the  objects  exposed. 
After  the  disinfection  is  finished  and  the  chamber  opened  the  heat  from 
the  steam  in  the  jacket  may  be  used  to  dry  the  objects  which  have  just 
been  steamed.  Therefore,  in  using  this  apparatus  for  disinfecting  with 
steam,  either  with  or  without  pressure,  the  steam  is  kept  circulating  in 
the  jacket  from  the  beginning  to  the  end  of  the  process. 

In  the  jacket  the  steam  has  a  perfectly  free  circulation,  so  that  the 
entire  disinfecting  cylinder,  with  the  exception  of  the  doors,  is  sur- 
rounded by  live  steam.  The  outer  shell  of  the  jacket  is  insulated  with 
a  covering  of  sectional  magnesia,  asbestos,  or  some  other  non-conduct- 
ing substance. 

The  steam  from  the  boiler  passes  through  the  main  steam  pipe  A 
(Fig.  160)  to  the  pressure-reducing  valve  (2),  and  thence  to  the  bottom 
of  the  jacket  at  B,  B. 

Into  the  disinfecting  chamber  itself  the  steam  can  be  admitted 
only  from  the  jacket,  through  the  circulating  pipes,  A,  C,  B  (Fig. 
158),  and  after  circulating  through  the  disinfecting  chamber  in  the  direc- 
tion as  shown  by  the  arrows  is  allowed  to  pass  out  with  the  drip  through 
the  drain  D  (Fig.  159).  Upon  the  completion  of  the  process  the  steam 
may  be  blown  off  through  the  vacuum  pipe  F,  but  this  outlet  should  not 
be  used  during  the  steaming  because  the  desired  circulation  would  not  be 
obtained. 

It  will  be  noticed  that  the  steam  is  admitted  at  the  bottom  of  the 
jacket,  and  at  the  top  of  the  disinfecting  chamber,  as  shown  in  Fig.  158. 
The  object  of  admitting  the  steam  at  the  top  of  the  disinfecting  chamber 
is  to  favor  the  expulsion  of  the  air  through  its  outlet  at  the  bottom  by 
means  of  the  descending  column  of  steam.  Therefore,  in  order  to  expel 
all  the  air  and  fill  the  chamber  with  steam  it  is  essential  to  open  the 
drain  D  (Fig.  159)  while  the  steam  is  entering  through  B,  B,  and 
this  outlet,  D,  should  not  be  closed  until  steam  escapes  freely.  In  using 
the  vacuum  attachment  to  expel  the  air  contained  in  the  apparatus  the 
modtis  operandi  is  somewhat  different. 

A  partial  vacuum  may  be  obtained  in  steam  chambers  of  this  type 
with  the  ejector  (4,  Fig.  160).  The  object  of  the  vacuum  is  to  facilitate 
the  penetration  of  the  steam,  which  rushes  into  all  the  interstices  of 
fabrics  and  inaccessible  places,  to  take  the  place  of  the  air  which  has  been 
withdrawn.  The  ejector  works  upon  the  familiar  principle  of  the  water 
vacuum  pump,  the  air  being  drawn  or  sucked  along  with  the  current. 


PHYSICAL  AGENTS  OF  DISINFECTION 


1127 


With  a  pressure  of  80  pounds  in  the  boiler  and  the  valve  J  (Fig.  160) 
wide  open  the  ejector  will  produce  a  partial  vacuum  of  15  inches  in  one 
of  the  largest  sized  chambers  in  one  minute,  which  is  very  much  quicker 
than  can  be  accomplished  with  the  ordinary  forms  of  piston  pumps. 


Any  steam  disinfecting  chamber  may  have  attached  to  it  an  appa- 
ratus for  generating  formaldehyd  gas,  so  that  objects  that  are  injured 
by  exposure  to  steam  may  be  disinfected  with  formaldehyd,  plus  dry 


1128 


PHYSICAL  AGENTS  01^^  DISINFECTION 


heat.  Before  the  formaldehyd  is  admitted  into  the  chamber  a  partial 
vacuum  may  be  established  by  means  of  the  ejector.  In  this  way  the 
penetration  of  the  gas  is  very  much  facilitated. 

In  the  best  patterns  the  steam  disinfecting  cylinders  are  open  at 
both  ends,  so  that  the  infected  objects  may  be  introduced  from  one  side 


and  taken  out  from  the  other,  which  diminishes  the  risk  of  reinfecting 
them.  The  joint  between  the  door  and  the  chamber  is  made  tight  by 
means  of  a  heavy  rubber  gasket.  The  door  should  not  be  pressed  against 
this  gasket  more  firmly  than  is  found  necessary  to  retain  the  steam, 
otherwise  the  rubber  will  soon  be  rendered  useless.  Wlien  not  in  use  the 
door  should  be  kept  open,  otherwise  on  cooling  the  metal  will  adhere 


PHYSICAL  AGENTS  OF  DISINFECTION  1129 

to  the  rubber  gasket.     This  may  be  prevented  to  a  certain  extent  by- 
keeping  the  rubber  gasket  covered  with  graphite. 

In  addition  to  the  above-mentioned  attachments  the  disinfecting 
chambers  are  also  supplied  with  a  thermometer  (7,  Fig.  160),  the  stem 
of  Avhich  is  turned  at  right  angles  and  protrudes  so  as  to  indicate  the 
temperature  of  the  interior  of  the  disinfecting  chamber.  The  thermom- 
eter, however,  is  so  close  to  the  jacket  that  it  is  influenced  by  the  heat  in 
the  jacket,  which  is  usually  higher  than  the  temperature  of  the  interior 
of  the  chamber.  The  thermometer  should  be  in  the  door,  or  differently 
arranged,  to  give  trustworthy  results.  In  disinfecting  with  steam  under 
pressure  the  pressure,  as  indicated  by  the  gage,  is  a  more  reliable  guide 
than  the  temperature  registered  by  the  thermometer.  There  are  forms 
of  mercurial  and  metallic  thermometers  that  make  an  electric  contact 
when  a  certain  temperature  is  reached,  and  which  may  be  connected  to 
ring  a  bell.  They  have  a  decided  advantage  in  that  they  may  be  placed 
anywhere  within  the  chamber,  even  in 
the  center  of  bundles,  etc.,  and  are 
more  trustworthy  than  any  form 
of  mercurial  instrument  fastened 
through  the  heavy  metallic  walls  of 
tlie  apparatus. 

An  ingenious  form  of  thermome- 
ter, made  to  register  when  the  tem- 
perature   reaches    100°    C,    has    been       Fig.  161.— Automatic  Thermometer 
designed  by  Merk,  and  is   shown  in 

the  accompanying  illustration  (Fig.  161).  A  small  stick  of  the  me- 
tallic substance  which  is  supplied  with  the  instrument  and  which  melts 
at  exactly  100°  C,  fastened  at  A,  keeps  the  electrodes  at  B  and  C  apart. 
The  entire  thermometer  D  is  then  placed  in  the  box  E  for  protection,  and 
this  is  placed  in  the  chamber  or  in  the  inside  of  bundles  to  be  disin- 
fected. The  insulated  wires  from  F  and  G  are  connected  with  a  battery 
and  bell.  As  soon  as  the  temperature  reaches  100°  C.  the  little  metal 
stick  melts,  the  contact  is  made  between  B  and  C,  and  the  bell  rings. 
This  form  of  thermometer  is  more  accurate  than  the  pyrometers,  which 
depend  upon  the  contact  being  made  by  the  unequal  expansion  of  a  com- 
pound metal  bar,  for  the  reason  that  moisture  collects  upon  the  electrodes 
and  an  electric  contact  is  sometimes  made  before  the  metal  parts  actually 
touch,  thereby  giving  false  readings. 

Steam  chambers  must  always  be  provided  with  galvanized  or  copper 
hoods  to  prevent  rust-stained  drip  from  soiling  the  clothing  and  othe' 
objects  exposed  to  the  steam;  gages  to  indicate  both  vacuum  and  steam 
pressure,  and  a  safety  valve  to  prevent  over-pressure  in  the  chamber. 
The  amount  of  pressure  from  the  boiler  is  regulated  by  a  reducing  valve 
in  the  main  steam  pipe. 


1130 


niVSICAI.  ArjKXTS  OF  DrSTXFI'X'TION 


For  convenience  in  handling  the  goods  cars  are  provided,  of  light 
wrought-iron  construction,  with  movable  trays  made  of  galvanized 
screens ;  also  bronze  hooks  at  the  top  of  the  car,  permitting  the  articles 

to  be  laid  upon  the  trays  or 
to  be  hung  up  on  the  hooks. 

In  the  accompanying  dia- 
gram (Fig,  162)  the  method 
of  installing  the  steam  cham- 
bers in  the  disinfecting  shed 
of  a  quarantine  station  is 
shown.  It  will  be  noted  that 
the  cylinders  open  on  both 
ends,  and  that  a  dividing 
wall  running  across  the 
building  separates  the  receiv- 
ing end,  where  the  infected 
objects  arrive  and  are  pre- 
pared for  disinfection,  from 
the  discharging  end,  where 
the  contents  of  the  chamber 
are  aired,  dried,  and  re- 
packed after  disinfection. 

This  separation  is  essen- 
tial where  a  large  amount  of 
..,  ^^      disinfection    is    done    for    a 

I i  1  ■iy   y  /{y   y  I      «  S      variety    of    diseases,    as,    for 

»     -r      _i      ...  >    •    .,ji   •!  ph  rn      example,  m  a  municipal  dis- 

infecting establishment  or  at 
the  quarantine  station  of  a 
busy  port.  It  is  true  that 
the  infection  of  certain  dis- 
eases is  not  apt  to  contami- 
nate the  surroundings,  and 
in  such  cases  there  would 
be  little  risk  in  taking  the 
disinfected  articles  out  of  the 
same  end  of  the  chamber 
from  which  they  are  put  in, 
especially  if  the  exposed  sur- 
faces are  mopped  with  a  dis- 
infectant in  the  interim. 
'But  this  is  a  risk  that  need  not  be  taken;  in  fact,  all  well-regulated 
disinfecting  plants  maintain  a  rigid  separation  between  the  two  sides, 
never  allowing  both  doors  of  the  chamber  to  be  open  at  the  same  time. 


PHYSICAL  AGENTS  OF  DISINFECTION 


1131 


and  providing  two  sets  of  workmen,  one  for  the  "infected"  and  one 
for  the  "disinfected"  side. 

The  chambers  must  be  loaded  with  care  in  order  to  obtain  reliable 
results  and  to  avoid  injuring  the  articles  exposed  to  the  process.  The 
packages  must  not  be  too  large  or  crowded  too  closely,  for,  although  the 
vacuum  facilitates  the  penetration  of  the  steam,  there  is  a  limit  in  this 
regard;  it  takes  so  much  longer  for  disinfecting  agents  to  penetrate 
dense  packages  and  bundles  that  there  is  little  saving  of  time  and  a  dis- 
tinct loss  in  trustworthiness.  Steam  cannot  penetrate  compressed  bun- 
dles of  rags,  bales  of  cotton,  feathers,  hair,  or  other  packages  of  mer- 
chandise which  are  often  presented  for  disinfection.  Fortunately,  it  is 
seldom  necessary  to  disinfect  such  packages.     When,  however,  this  is 


Fig.  163. 


called  for  it  is  essential  to  open  and  properly  expose  such  objects  to  the 
action  of  the  disinfecting  agent. 

In  the  municipal  disinfecting  stations  of  Paris  the  process  of  apply- 
ing steam  under  pressure  is  as  follows:  The  pressure  is  brought  up  to 
15  pounds  in  the  chamber  and  held  there  five  minutes;  then  released. 
The  pressure  is  again  brought  up  to  15  pounds,  held  there  five  minutes, 
and  again  released.  This  is  repeated  three  times,  when  the  disinfection 
is  completed.  The  cylinders  are  fitted  with  an  ingenious  arrangement 
for  the  automatic  registration  of  the  process.  Each  chamber  is  con- 
nected by  a  small  copper  tube  to  a  register  with  a  moving  pen  and  re- 
volving drum  carrying  a  chart.  The  horizontal  lines  1  to  10  on  the 
chart  each  represent  a  pressure  of  one-tenth  of  an  atmosphere,  and  the 
vertical  lines  represent  five  minutes  in  the  revolution  of  the  drum.  Each 
steaming-  is  represented  thus : 

These  charts,  which  can  be  removed  only  by  the  chief  of  the  station, 
are  sent  each  day  to  the  Inspector-General,  and  give  a  perfect  guarantee 
that  each  steaming  has  been  done  as  directed. 


CHAPTER  III 
CHEMICAL  AGENTS   OF   DISINFECTION 

GASEOUS  DISINFECTANTS— FUMIGATION 

A  germicidal  gas  would  be  an  ideal  weapon  for  destroying  such  in- 
visible foes  as  we  have  to  deal  with  in  public  health  work,  especially 
for  terminal  disinfection.  By  reaching  all  portions  of  a  room  or  confined 
space  a  gas  lessens  the  risk  of  overlooking  any  surface  upon  which  the 
infective  agent  may  be  lodged,  but  the  ideal  gas  for  this  purpose  is  still 
to  be  discovered. 

There  is  practically  only  one  gas  suitable  for  general  application, 
viz.,  formaldehyd.  This  substance  comes  nearer  being  an  ideal  disin- 
fectant than  any  of  the  gases  in  general  use.  It  is  not  poisonous,  does 
not  injure  fabrics,  colors,  metals,  or  objects  of  art  and  value.  Formalde- 
hyd, however,  has  distinct  limitations,  which  are  dealt  with  more  in 
detail  under  the  description  of  the  gas. 

Sulphur  dioxid  is  too  destructive  for  fabrics,  colors,  and  metals  for 
general  use.  It  is  a  better  insecticide  than  germicide.  It  is  very  poison- 
ous to  all  forms  of  animal  life,  which  makes  it  valuable  in  fumigating 
against  insect  and  animal-borne  diseases.  It  has  no  equal  for  the 
fumigation  of  the  holds  of  ships,  cellars,  sewers,  stables,  and  other 
rough  structures  infested  with  vermin. 

The  very  poisonous  and  destructive  nature  of  chlorin  gas  contracts 
its  usefulness  to  narrow  limits. 

Hydrocyanic  acid  gas  is  too  poisonous  to  use  in  the  household,  and 
is  limited  in  practice  to  the  destruction  of  infection  and  vermin  on 
board  ships,  in  warehouses,  greenhouses,  granaries,  railroad  cars,  and 
other  uninhabited  or  isolated  structures. 

None  of  the  gaseous  agents  can  be  depended  upon  for  more  than  a 
surface  disinfection.  They  all  lack  the  power  of  penetration.  Practically 
all  the  gaseous  agents  are  not  disinfectants  but  fumigants  (see  page  208). 

Preparation  of  the  Room. — The  preparation  of  a  room  or  space  to  be 
fumigated  with  a  gas  is  a  matter  of  some  importance.  A  larger  amount 
of  gas  than  is  thought  possible  is  lost  through  leaks,  by  diffusion,  by 
absorption  and  in  other  ways;  therefore  the  room  should  be  made  tight, 
all  cracks  and  crevices  should  be  well  closed  by  pasting  paper  over  them 
or  by  caulking  with  suitable  material  of  some  kind.     Do  not  forget  to 

1132 


GASEOUS  DISINFECTANTS— FUMIGATION  1133 

close  the  registers,  flues,  hearths,  and  ventilators,  and  look  carefully  for 
openings  in  out-of-the-way  places.  Then  expose  the  objects  in  j;he  room 
so  that  the  gas  may  have  ready  access  to  all  the  surfaces.  Move  bureaus, 
beds,  and  furniture  away  from  the  walls,  open  doors  of  closets,  drawers 
of  bureaus,  lids  of  boxes,  and  the  like  so  that  the  gas  may  freely  enter 
and  diffuse  to  all  corners.  None  of  the  gases  can  be  depended  upon  to 
disinfect  clothing,  bedding  and  fabrics. 

While  the  articles  in  the  room  must  be  arranged  so  that  the  gas  may 
freely  gain  access  to  all  surfaces  possible,  the  mistake  must  not  be  made 
of  going  to  the  opposite  extreme  of  disarranging  the  contents  of  the 
room  too  much,  for  the  same  surfaces  should  be  exposed  to  the  gas  that 
were  exposed  to  the  infection. 

The  strength  of  the  gas  and  time  of  the  exposure  necessary  to  insure 
disinfection  have  been  determined  by  exact  laboratory  experiments,  but 
the  conditions  found  in  actual  practice  are  so  variable  that  we  must 
allow  for  a  liberal  excess  to  make  up  for  inevitable  wastage.  Wind  pres- 
sure also  seriously  influences  the  efficiency  of  gaseous  disinfectants  in 
a  confined  space.  Much  more  air  than  is  commonly  thought  possible 
forces  its  way  through  cracks  and  through  the  walls  themselves.  The 
wind  pressure  may  thus  drive  the  fumigating  gas  entirely  away  from 
one  side  of  the  room.  It  is  only  necessary  to  stand  upon  the  leeward  side 
of  a  structure  being  disinfected  with  sulphur  dioxid  or  formaldehyd  to 
realize  the  great  quantity  of  gas  blown  from  the  enclosure. 

Formaldehyd  Gas. — Formaldehyd  ^  is  the  most  generally  useful  and 
one  of  the  best  disinfecting  gases  that  we  possess.  Its  superiority  de- 
pends upon  its  high  value  as  a  germicide,  its  non-poisonous  nature,  and 
upon  the  fact  that  it  is  not  destructive.  The  secret  of  successful  disin- 
fection with  this  substance  is  to  obtain  a  large  volume  of  the  gas  in  a 
short  time. 

Formaldehyd  (HCHO)  exists  in  at  least  three  well-recognized  iso- 
meric states : 

(1)  Formaldehyd  (formic  aldehyd)  is  a  gas  at  ordinary  tempera- 
tures, colorless,  and  possessing  slight  odor,  but  having  an  extremely  irri- 
tating effect  upon  the  mucous  membranes.  At  a  temperature  of  about 
—  20°  C.  the  gas  polymerizes  into  paraformaldehyd,  known  commercially 
as  paraform. 

(2)  Paraform  is  a  white  substance,  unctuous  to  the  touch,  soluble 
in  both  water  and  alcohol.  It  consists  chemically  of  two  molecules 
of  formaldehyd.  It  is  this  substance  which  is  supposed  to  compose  the 
commercial  solutions  of  formaldehyd  known  as  formalin,  formol,  etc. 

(3)  Trioxymethylene  is  formed  by  the  union  of  three  molecules  of 
formaldehyd.  It  is  a  white  powder  giving  off  a  strong  odor  of  the  gas. 
It  is  but  slightly  soluble  in  alcohol  and  water. 

^Formaldehyd  is  the  gas,  formalin  is  the  aqueous  solution  of  the  gas. 


1134  CIIEMICAI.  AGExNTS  OF   DISlx\FECTJ()X 

J^'ormaldehyd  gas  possesses  about  the  same  specific  gravity  as  air; 
it  diffuses  slowly,  although  somewhat  better  than  sulphuric  dioxid.  Form- 
aldeliyd  combines  with  nitrogenous  organic  matter,  A  few  drops  added 
to  the  white  of  an  egg  will  prevent  its  coagulation  by  heat.  The  form- 
aldehyd  unites  with  the  albumin  to  form  a  totally  new  compound. 
Combined  with  gelatin  it  keeps  that  substance  from  liquefying.  It  is 
from  this  property  of  combining  directly  with  the  albumins  forming  the 
protoplasm  of  the  microorganisms  that  formaldehyd  is  supposed  to  de- 
rive its  power  as  a  germicide.  It  is  perfectly  plain,  therefore,  why  there 
must  be  direct  contact  between  the  gas  and  the  germ  in  order  to  accom- 
plish disinfection. 

Formaldehyd  also  unites  readily  with  the  nitrogenous  products  of  de- 
composition, forming  new  chemical  compounds  which  are  both  odorless 
and  sterile.  It  is  thus  a  true  deodorizer  in  that  it  does  not  mask  one 
odor  by  another  still  more  powerful,  but  forms  new  chemical  bodies 
which  possess  no  odor. 

Formaldehyd  apparently  has  no  detrimental  effects  upon  silks,  wool- 
ens, cotton,  and  linen.  It  does  not  change  colors,  with  the  exception 
possibly  of  a  slight  effect  upon  some  of  the  delicate  anilin  lavenders.  An 
oil  painting  is  not  perceptibly  altered  after  prolonged  exposure  to  the 
gas.  The  metals  are  not  attacked.  It  is  this  non-destructive  property 
of  the  gas  that  renders  it  generally  applicable.  It  is  practically  the  only 
gaseous  germicide  which  can  be  used  in  the  richest  apartments,  contain- 
ing objects  of  art  and  value,  without  fear  of  damage. 

The  commercial  solutions  known  as  formalin  are  said  to  contain  40 
per  cent,  of  formaldehyd  gas.  They  are  not  always  up  to  standard  (aver- 
age 36  per  cent.),  and,  being  volatile,  there  is  a  certain  loss  if  not  well 
kept.  In  winter  there  is  a  decided  deterioration,  owing  to  the  polymeri- 
zation and  precipitation  of  trioxymethylene.  This  substance  is  often 
found  in  abundance  at  the  bottom  of  the  bottle  or  carboy  as  a  white  pre- 
cipitate. For  these  reasons  it  is  well  to  use  an  excess  of  the  liquid  in 
practical  work  if  the  exact  strength  of  the  formalin  has  not  recently  been 
determined. 

Formalin  solutions  of  commerce  are  almost  all  acid  in  reaction,  due 
in  part  to  formic  acid.  Some  of  the  commercial  solutions  also  contain 
a  certain  amount  of  wood  alcohol  (about  10  per  cent.)  which  is  added 
to  increase  their  solubility  and  stability. 

A  certain  amount  of  heat  and  moisture  is  necessary  to  obtain  suc- 
cessful disinfection  with  formaldehyd  gas.  The  exact  amount  of  mois- 
ture necessary  depends  somewhat  upon  the  temperature.  As  a  general 
working  rule  it  may  be  stated  that  if  the  temperature  is  below  65°  F. 
or  if  the  relative  humidity  is  below  60  per  cent,  the  results  become  irregu- 
lar ;  much  below  these  figures  the  results  are  unreliable,  especially  if  the 
space  is  both  cold  and  dry.     Formaldehyd  polymerizes  at  low  tempera- 


GASEOUS  DISINFECTANTS— FUMIGATIOX  1135 

tures,  therefore  in  cold  weather  it  may  be  necessary  to  artificially  warm 
the  room  to  be  disinfected.  In  dry  weather  moisture  should  be  added  to 
the  room. 

Formaldehyd  gas  cannot  be  depended  upon  to  accomplish  more  than 
a  surface  disinfection.  Under  ordinary  circumstances  it  possesses  small 
powers  of  penetration.  It  takes  a  large  volume  and  a  long  exposure  to 
penetrate  several  layers  of  thin  fabrics.  The  gas  polymerizes  in  the 
meshes  of  the  fabric  and  is  deposited  as  paraform  upon  surfaces.  Large 
quantities  of  the  formaldehyd  are  lost  by  uniting  chemically  with  the 
organic  matter  of  fabrics,  especially  woolens,  which  further  hinders  its 
penetration.  Therefore,'  formaldehyd  gas  cannot  be  relied  upon  to  dis- 
infect fabrics,  especially  quilted  goods  and  materials  requiring  deep  pene- 
tration. 

Formaldehyd  gas  has  the  power  of  killing  spores,  although  not  with 
sufficient  certainty  to  render  it  a  trustworthy  agent  for  infections  such 
as  anthrax  and  tetanus.  It  has  the  great  advantage  of  killing  dry  micro- 
organisms, although  not  quite  so  readily  as  when  they  are  moist. 

Bacteria  exposed  directly  to  the  action  of  a  concentrated  volume  of 
formaldehyd  gas  are  killed  almost  instantly,  but  in  practical  work  it  is 
necessary  to  prolong  the  time  of  exposure  to  6  or  12  hours,  as  it  takes 
considerable  time  for  the  gas  to  permeate  to  all  the  corners  and  dead 
spaces  of  a  room.  Bacteria  are  not  always  directly  exposed  upon  the  sur- 
face of  objects,  as  they  are  in  laboratory  experiments,  and,  furthermore, 
they  are  frequently  imbedded  in  albuminous  matter  or  in  dust,  both  of 
which  retard  the  action  of  the  gas. 

Formaldehyd  gas  is  not  very  toxic  to  the  higher  forms  of  animal  life, 
although  it  stands  at  the  head  of  the  list  of  germicides.  Long  exposure 
to  weak  atmospheres  of  the  gas  sufficient  to  kill  germs  has  but  slight 
effect  upon  animals.  Guinea-pigs,  rats,  mice,  and  rabbits  exposed  to 
concentrated  atmospheres  are  not  killed  after  half  an  hour's  exposure. 
The  only  effect  produced  is  a  violent  irritation  of  the  mucous  membranes 
of  the  respiratory  tract,  from  which  the  animals  may  subsequently  die. 
Microorganisms  exposed  to  this  same  concentration  of  the  gas  are  killed 
almost  instantly. 

Formaldehyd  is  rapidly  absorbed  from  all  parts  of  the  gastro-intes- 
tinal  tract  and  lungs,  and  may  be  excreted  again  by  them.  It  is  rapidly 
oxidized  in  the  body  to-formic  acid  and  carbonates.  There  is  also  a  small 
amount  of  a  dialyzable  compound  formed  in  the  blood  which  is  most 
probably  hexamethylenamin  since  the  latter  is  found  in  the  urine.  Small 
amounts  of  formaldehyd  may  pass  through  the  body  without  causing  ap- 
parent inflammation,  while  large  amounts  always  cause  some. 

Formaldehyd  is  not  an  insecticide.  In  the  strongest  volumes  of  the 
gas  obtainable  it  seems  to  have  practically  no  effect  upon  roaches,  bed- 
bugs, aud  insects  having  strong  Hiitinous  coverings.     It  may  kill  the 


113G 


CHEMICAL  AGENTS  OF  DISINFECTION 


frailer  insects,  but  its  action  is  uncertain ;  thus  mosquitoes  may  live  in  a 
weak  atmosphere  of  the  gas  over  night. 

Upon  the  completion  of  the  time  required  to  disinfect  a  room  it  is 
best  to  open  all  the  doors  and  windows  and  let  the  gas  blow  away.  This 
may  be  a  troublesome  procedure.  If  the  windows  can  be  reached  from 
the  outside  it  is  easy  enough,  but  if  the  room  must  be  entered  it  is  ad- 
visable for  the  operator  to  cover  his  mouth  and  nose  with  a  moist  towel 
and  act  quickly.  It  was  formerly  the  custom  to  neutralize  the  gas  with 
ammonia,  but  this  is  little  practiced  now.  The  ammonia  neutralizes  the 
formaldehyd  by  the  production  of  hexamethylene-tetramine. 

The  following  methods  are  used  for  disinfection  with  formaldehyd 


(1 

(3 
(3 
(4 
(5 
(6 
(^ 
(8 


Autoclave  under  pressure. 

Eetort  without  pressure. 

Generator  or  lamp. 

Formaldehyd  and  dry  heat  in  partial  vacuum. 

Spraying. 

Heating  paraform. 

Potassium  permanganate  and  formalin. 

Formalin,  lime,  and  aluminium  sulphate. 
The  most  generally  useful  of  these  methods  are  the  last  two.     They 

have  the  great  advantage  of  sim- 
plicity, of  dispensing  with  all  ap- 
paratus, and  of  evolving  a  large 
amount  of  the  gas  in  a  short  time. 

The  Permanganate-Forma- 
lin Method. — Use  500  c.  c.  of 
formalin  and  250  grams  of  potas- 
sium permanganate  for  each  thou- 
sand cubic  feet  of  air  space.  The 
permanganate  is  first  placed  in  a 
bucket  or  basin  and  the  formalin 
poured  upon  it.  An  active  effer- 
vescence takes  place  and  consider- 
able heat  is  evolved;  therefore  a 
pail  of  sufficient  capacity,  and  es- 
pecially of  sufficient  height,  should 
be  used  to  prevent  splashing  or 
boiling  over.  In  Board  of  Health 
work  it  is  advisable  to  have  gal- 
vanized iron  pails  made  for  this 
purpose  with  a  flaring  top.  The  floor  should  be  protected  against  the 
heat  by  placing  the  bucket  upon  a  brick,  board,  or  other  suitable  device. 
When  the  permanganate  of  potassium  and  formalin  are  brought  in 


Fig.  164. — Flaring  Top  Tin  Bucket 
FOE  Generating  Formaldehyd  by 
THE  Permanganate  Method.  Height 
15  inches,  diameter  10  inches  at  base, 
15  inches  at  top  of  flare. 


GASEOUS  DISINFECTANTS— FUMIGATION  1137 

contact  very  active  oxidation  takes  place,  with  the  production  of  formic 
acid  and  heat.  It  is  the  heat  that  liberates  the  formaldehyd  gas.  Chem- 
ically, therefore,  the  method  is  a  wasteful  one,  but  practically  a  very 
serviceable  one.  It  was  first  described  by  Johnson  of  Sioux  City,  Iowa, 
in  1904.  In  the  same  year  Evans  and  Eussell  of  Augusta,  Maine,  used 
the  method. 

The  formula  recommended  by  the  Pennsylvania  Department  of 
Health  is : 

Sodium  dichromate 10      ounces 

Formalin 16  " 

Commercial  sulphuric  acid IH        " 

The  sulphuric  acid  can  be  added  to  the  formalin  and  the  mixture 
kept  on  hand  for  use ;  polymerization  in  cold  weather  can  be  avoided  by 
the  addition  of  glycerin,  ll^  ounces.  The  acid  formalin  is  poured  on 
the  crystals  of  sodium  dichromate  and  formaldehyd  gas  is  at  once  liber- 
ated. 

The  Formalin-Lime  and  Aluminium-Sulphate  Method. — This 
method  was  first  described  by  Walker  of  the  Department  of  Health, 
Brooklyn,  N.  Y.  It  is  somewhat  slower  than  the  potassium  permanga- 
nate method,  but  otherwise  appears  to  be  just  as  efficient. 

The  proportions  for  each  1,000  cubic  feet  are  as  follows: 

Sol.  A. — Aluminium  sulphate 150  grams 

Dissolved  in  hot  water 300  c.  c. 

Sol.  5.— Formalin  (40  per  cent.  CHOH) 600  c.  c. 

Lime. — Unslaked  lime 2,000  grams 

Mix  solutions  A  and  B  and  pour  upon  the  lime. 

In  practical  work  20  to  25  pounds  of  the  commercial  aluminium  sul- 
phate is  dissolved  in  5  gallons  of  hot  water.  This  is  sufficient  to  mix  with 
15  gallons  of  a  40  per  cent,  formaldehyd  solution  and  then  used  in  the 
proportions  as  stated  above.  The  lime  should  be  freshly  burned,  broken 
into  small  particles,  and  should  slake  rapidly  in  cold  water.  The  lime  is 
jolaced  in  a  large  bucket.  The  formalin  and  aluminium  sulphate  solu- 
tions should  be  mixed  and  poured  over  the  lime.  In  a  few  minutes 
the  lime  begins  to  slake  and  the  heat  evolved  drives  off  the  formaldehyd 
gas. 

The  Spraying  Method. — Spraying  formalin  is  a  satisfactory  and 
simple  method  of  disinfecting  small  inclosures,  such  as  wardrobes, 
closets,  and  cabinets.  It  is  not  practical  for  larger  rooms.  If  the  for- 
malin is  sprayed  directly  upon  the  objects  to  be  disinfected  they  enjoy 
the  direct  germicidal  action  of  the  substance  in  solution  and,  further,  are 
bathed  in  the  gas  which  is  slowly  evolved.  The  method  is  particularly 
serviceable  for  the  disinfection  of  bureau  drawers,  closets,  and  small 


1138  CHEMlCAJj  AGENTS  OF  DISINFECTION 

spaces.  When  used  to  disinfect  small  rooms  suspend  a  bed  sheet  from  a 
line  stretched  across  the  middle  of  the  room.  An  ordinary  bed  sheet 
presenting  a  surface  of  about  2  by  2y2  yards  is  required  for  every  1,000 
cubic  feet  of  space  of  the  room.  Properly  sprinkled  this  will  carry, 
without  dripping,  8  ounces  of  formalin.  The  ordinary  sprinkling  pot 
used  by  florists  can  be  used  to  spray  the  sheets  and  a  liberal  ex- 
cess should  be  used.  The  room  should  remain  closed  not  less  than  eight 
hours. 

The  other  methods  for  disinfecting  with  formaldehyd  gas  are  not 
described  because  most  of  them  are  unreliable,  and  none  of  them  is 
as  serviceable  in  practical  work  as  the  formalin-permanganate  method 
or  the  formalin-lime  method. 

Sulphur  Dioxid. — Sulphur  dioxid  (SO2)  is  not  a  very  efficient  germi- 
cidcj  but  is  exceedingly  poisonous  to  mammalian  and  insect  life.  It 
is  this  property  which  makes  it  of  especial  value  as  a  fumigant  against 
diseases  spread  by  rats,  mice,  flies,  fleas,  mosquitoes,  etc.  For  this  pur- 
pose it  has  no  suj)erior. 

The  action  of  sulphur  dioxid  as  a  germicide  depends  upon  the  pres- 
ence of  moisture.  The  dry  gas  is  practically  inert  against  bacteria.  Sul- 
phur dioxid  cannot  be  depended  upon  where  penetration  is  required.  Its 
action  is  merely  upon  the  surface.     It  does  not  kill  spores.  • 

Sulphur  dioxid  possesses  the  advantage  of  being  cheap  and  readily 
procurable.  There  is  hardly  a  crossroad  store  in  the  country  where  a 
reasonable  quantity  of  sulphur,  either  in  the  form  of  flowers  or  in  rolls 
or  sticks  under  the  name  of  brimstone,  cannot  be  obtained.  Sulphur 
dioxid  is  especially  applicable  to  the  holds  of  ships,  freight-cars,  gran- 
aries, stables,  out-houses,  and  similar  rough  structures — particularly  if 
infested  with  vermin. 

The  disadvantages  of  sulphur  dioxid  as  a  disinfecting  agent  are  such 
as  to  contract  its  application  to  rather  narrow  limits.  It  bleaches  all 
coloring  matter  of  vegetable  origin  and  many  anilin  dyes.  It  attacks 
almost  all  metals ;  it  acts  upon  cotton  and  linen  fabrics  so  as  to  seriously 
weaken  their  tensile  strength,  especially  if  starched. 

Sulphur  dioxid  is  a  heavy,  colorless,  irrespirable  gas  with  a  peculiar 
suffocating  odor  and  irritating  properties.  It  has  a  density  of  2.4.  On 
account  of  the  heavy  specific  gravity  as  compared  to  air  it  diffuses 
slowly  and  then  settles  toward  the  bottom  of  the  compartment. 

Cold  water  takes  up  more  than  30  times  its  volume  of  sulphur  dioxid. 
The  solution  contains  sulphurous  acid  (HgSOg),  and  it  is  in  reality 
this  acid  that  is  the  disinfecting  agent.  The  dry  gas  is  therefore  inert 
and  moisture  is  essential  in  order  to  obtain  any  germicidal  effect.  It  is 
also  this  acid  and  some  sulphuric  acid  which  has  such  a  destructive  effect 
upon  fibers,  colors,  and  metals.  The  corrosive  action  of  these  acids  upon 
fabrics  takes  place  slowly,  and  the  damage  may  largely  be  obviated  if 


GASEOUS  DISINFECTANTS— FUMIGATION  1139 

they  are  washed  at  once.  ]\Ietal  work  may  be  protected  by  coating  it  with 
a  thin  layer  of  vaselin  or  heavy-bodied  oil. 

Sulphur  dioxid  may  readily  be  condensed  into  a  clear  liquid  by  either 
cold  or  pressure  or  a  combination  of  both.  At  ordinary  atmospheric 
pressure  it  condenses  if  the  temperature  is  reduced  to  — 18°  C,  which 
is  about  the  temperature  of  a  mixture  of  ice  and  salt.  At  ordinary  tem- 
peratures it  liquefies  if  the  pressure  is  raised  to  about  four  atmospheres, 
that  is,  60  pounds.  This  liquid  is  a  stable  substance  when  kept  well 
sealed  and  protected  from  the  action  of  the  air.  It  rapidly  volatilizes 
when  poured  into  an  open  vessel.  It  is  now  found  in  commerce  and  is 
one  of  the  methods  used  for  producing  the  gas  for  fumigating  purposes. 

The  complete  combustion  of  1  pound  of  sulphur  in  a  space  of  1,000 
cubic  feet  will  theoretically  produce  1.115  per  cent,  of  sulphur  dioxid, 
but  this  amount  cannot  be  obtained  in  practice  because  the  sulphur  of 
commerce  contains  impurities  such  as  sulphate  of  lime  and  sand,  and  a 
portion  of  the  burning  sulphur  is  always  oxidized  to  the  formation  of  ill- 
defined  compounds.  Therefore  one  pound  may.  be  considered  as  pro- 
ducing approximately  1  per  cent,  of  the  gas  by  being  burned  in  1,000 
cubic  feet  of  space,  and  five  pounds  will  generate  approximately  5  per 
cent.,  which  is  the  maximum  theoretical  amount  obtainable  by  burning 
sulphur  in  a  confined  space.  Five  pounds  per  1,000  cu.  ft.  is  the  amount 
usually  used  when  a  germicidal  action  is  desired.  Somewhat  less,  2  to  4 
pounds,  is  sufficient  to  destroy  insects  and  rats. 

The  amount  of  moisture  necessary  to  convert  sulphur  dioxid  into 
sulphurous  acid  is  readily  computed.  It  will  be  found  that  one-fifth  of 
one  pound  of  water  should  be  volatilized  for  each  pound  of  sulphur 
burned.  The  water  may  be  added  in  the  form  of  steam  or  in  the  form 
of  a  finely  divided  spray,  or  it  may  be  vaporized  by  the  heat  generated 
by  the  combustion  of  the  sulphur  itself.  The  latter  method  is  the  one 
that  commends  itself  in  practical  use,  and  is  described  under  the  "pot 
method." 

While  moisture  is  essential  for  the  germicidal  action  of  sulphur 
dioxid,  it  is  not  necessary  in  order  to  kill  insects  and  small  mammals. 
Dry  sulphur  dioxid  is  quite  as  efficacious  against  rats,  mice,  fleas,  flies, 
mosquitoes,  bedbugs,  roaches,  etc.,  as  the  moist  gas. 

In  disinfecting  with  sulphur  dioxid  it  is  necessary  to  seal  the  com- 
partment tightly.  The  gas  is  disengaged  so  slowly  that  it  may  escape 
•  through  cracks  and  crevices  almost  as  fast  as  it  is  formed.  In  cold 
weather  the  heating  of  the  room  to  be  disinfected  will  greatly  aid  in 
the  disinfecting  action  of  the  gas. 

There  are  three  well-recognized  methods  of  fumigating  with  sulphur 
dioxid,  viz.,  (1)  the  pot  method,  (2)  liquid  sulphur  dioxid,  (3)  sulphur 
furnace. 

The  Pot  Method. — The  pot  method  is  at  once  the  easiest,  cheapest, 


1140 


CHEMICAL  AGENTS  OF  DTSTNFECTION 


Fig.   165. — The  Pot  Method  of  Burning  SuL' 

PHUB. 


and  probably  most  cllicieiit  mt'ili<j(l  of  iisiii;^  s'llphur  dioxid.  Tlio  only 
materials  required  are  iron  pots  and  S(nue  sulphur.  'I'lie  l)(;st  way  to 
apply  the  method  is  by  placing  the  sulphur  in  large,  flat,  iron  pots  known 
as  Dutch  ovens.  Not  more  than  30  pounds  of  sulphur  should  be  placed 
in  each  pot.  The  sulphur  is  preferably  used  in  the  form  of  flowers  of  sul- 
phur. If  it  is  in  sticks  or  rolls  it  should  be  crushed  into  a  powder,  which 
may  conveniently  be  done  by  placing  the  sulphur  in  a  stout  box  and 
pounding  the  lumps  with  a  heavy  timber.  The  pot  holding  the  sulphur 
should  be  placed  in  a  tub  of  water,  as  shown  in  Fig.  165.  The  water  not 
only  diminishes  the  danger  from  fire  and  protects  the  floor,  but  by  its 
evaporation  furnishes  the  moisture  necessary  to  hydrate  the  sulphur 
dioxid,  upon  which  the  disinfecting  power  of  the  gas  depends.  Thus  the 
moisture  is  furnished  automatically  and  does  away  with  the  necessity 
for  its  introduction  by  means  of  steam  or  a  spray.    Although  the  specific 

gravity  of  sulphur  dioxid  is 
greater  than  that  of  air, 
when  hot  it  rises,  aided  by 
the  upward  current  pro- 
duced by  the  burning  sul- 
phur. Hence  the  pots 
should  not  be  on  the  floor 
or  at  the  bottom  of  the  hold 
in  the  case  of  vessels  lest 
the  cold  gas  settle  and  the  flame,  being  deprived  of  oxygen,  be 
extinguished  before  all  the  sulphur  is  burned.  The  pots  may  therefore 
be  placed  upon  a  table  or  box  or,  in  the  holds  of  ships,  upon  piles  of  bal- 
last or  on  the  "  'tween  decks." 

Eoberts  and  McDermott^  suggest  that  the  sulphur  be  burned  upon 
pans  arranged  upon  a  rack  as  shown  in  Fig.  166,  instead  of  pots.  The 
advantages  of  this  stack  burner  are  that  a  large  amount  of  sulphur  may 
be  more  quickly  burned  in  less  time  than  is  possible  with  the  pot  method. 
Further,  the  intense  heat  below  each  pan  in  the  stack  burner  aids  the 
complete  and  rapid  burning  of  sulphur  in  the  pans  above  it.  A  stack 
burner  will  bum  sulphur  of  too  poor  a  quality  to  give  any  satisfaction  in 
the  pots.  The  ground  sulphur  is  placed  in  the  pans,  the  surface  of  the 
sulphur  is  moistened  with  alcohol,  and  ignited.  Each  shelf  should  be 
lighted  separately  to  save  time.  The  upper  pan  or  pans  may  be  filled 
with  water  to  hydrate  the  sulphur  dioxid  necessary  for  its  germicidal 
action. 

The  sulphur  may  be  lighted  by  means  of  hot  coals  or  a  wood  fire, 
but  the  most  reliable  way  to  get  it  well  lighted  is  by  alcohol,  turpentine, 
or  kerosene  on  a  pledget  of  waste.     Make  a  little  crater  of  the  sulphur, 

^PuUiG  Health  Reports,  U.  S.  P.  H.  and  M.  H.  S.,  March  31,  1911,  Vol. 
XXVI,   13,  p.  403. 


GASEOUS  DISINFECTANTS— FUMIGATION  1141 

soak  liberally  with  alcohol,  and  ignite.  The  sulphur  then  burns  in  the 
center,  and  as  it  melts  runs  down  from  the  sides  and  forms  a  little  lake 
at  the  bottom  of  the  crater.  If  the  sulphur  is  heaped  up  in  a  mound  in 
the  pot  the  flame  is  liable  to  go  out. 

Upon  the  principle  of  not  putting  all  our  eggs  in  one  basket,  it  is 
best  to  have  a  number  of  pots  when  a  large  compartment  is  to  be  fumi- 


FiG.  166. — Large  Stack  Burner  for  Sulphur,  with  15  of  the  18  Pans  Removed  to 

Show  Construction. 

gated.  A  pot  should  contain  not  more  than  30  pounds  of  sulphur,  and 
the  pots  should  be  well  distributed  in  various  portions  of  the  place  to 
be  disinfected. 

Use  5  pounds  per  1,000  cubic  feet  where  a  germicidal  action  is 
desired,  and  at  least  2  pounds  per  1,000  cubic  feet  for  insecticidal  pur- 
poses.    For  the  destruction  of  bacteria  an  exposure  of  from  6  to  24 

A    Safe   iuni   Ltttttm    n'^mft^Uint 

Hu^  Cjl.ndcr  Ln.i'airj,  iIm  ul  20  juni-eb  ot  Sulpuur  Dioxide 
-  inn.oi  l\  i-nuii  I  fjulpiiur  us  And  0-as  cond<:n-.cd  into  a 
hq  nil  t:\  I  rchour  n,  J  ,s  r.|u»l  m  t-lfua  ti  »bi  at  duubti.  Jtb 
v/ntJ"   ol  Su.pliui      s    irdimnH    1  ui  it   lor  d]",iiif.    lior 

I.ich  ac  iin<      CjUmi.  r   i--  -Ll^^rl,.^t  tu  ..iKcu/rli    Ji^inft    i 

Fig.  167. — Liquefied  Sulphur  Dioxid  in  Tin  Can. 


hours  is  necessary,  while  for  the  destruction  of  vermin  from  2  to  12 
hours  is  sufficient,  depending  upon  the  size  and  shape  of  the  compart- 
ment to  be  treated. 

Liquid  Sulphur  Dioxid. — Liquid  sulphur  dioxid,  commonly  known 
as  sulphurous  acid  gas,  while  efficient,  is  about  ten  times  as  expensive 
as  burning  sulphur  by  the  pot  method.     It  has  the  advantage  of  liber- 


1142  CHEMICAL  AGENTS  OF  DISINFECTION 

ating  a  large  volume  of  the  gas  rapidly,  tliereby  facilitating  its  dispersion. 
Further,  the  use  of  liquefied  sulj^hur  clioxid  has  the  advantage  of  avoid- 
ing the  danger  of  accidental  fire. 

One  pound  of  burning  sulphur  will  produce  about  2  pounds  of  sul- 
phur dioxid:  S(32)  +  02(32)  =  S02(64).  Therefore  2  pounds  of  the 
liquid  sulphur  dioxid  is  necessary  to  produce  the  same  volume  of  sulphur 
dioxid  as  is  generated  from  one  pound  of  the  burning  sulphur. 

The  method  of  using  the  liquid  sulphur  dioxid  is  very  simple.  If 
the  substance  is  bought  in  small  tins  it  is  only  necessary  to  cut  the 
lead  pipes  in.  the  tops  of  the  necessary  number  of  cans  and  invert  the 
latter  in  an.  ordinary  washbowl  or  iron  pot,  when  volatilization  rapidly 
occurs.  All  the  cans  must  be  cut  simultaneously  and  the  operator  must 
act  quickly  and  be  prepared  immediately  to  leave  the  room  and  shut 
the  door.  If  the  substance  is  contained  in  glass  or  metallic  siphons 
the  necessary  amount  of  liquid  sulphur  dioxid  can  be  projected  from 
the  outside  through  a  pipe  passed  through  the  keyhole  or  other  aperture. 
A  suitable  receptacle  should  be  arranged  on  the  inside  to  catch  the  drip 
and  frozen  mass  which  forms  as  a  result  of  the  expansion.  In  order  to 
obtain  the  maximum  disinfecting  power  with  this  method  it  is  necessary 
to  introduce  moisture.  This  may  be  done  by  placing  open  pans  of  boil- 
ing water  in  the  room,  by  injecting  steam,  or  by  a  fine  spray  of  water. 

The  Sulphur  Furnace. — The  sulphur  may  be  burned  in  an  ap- 
paratus of  special  construction  known  as  a  sulphur  furnace,  from  which 
the  resulting  fumes  are  blown  through  a  system  of  pipes  into  the  room 
or  hold  of  a  vessel  to  be  disinfected.  Two  forms  of  sulphur  furnace  are 
used:     (1)  the  Kinyoun- Francis  furnace,  and  (2)  the  Clayton  furnace. 

This  method  requires  expensive  and  cumbersome  machinery  and 
has  little  to  recommend  it  over  the  simpler  pot  method  except  that  a 
large  percentage  of  the  gas  may  be  blown  into  a  given  space.  The  pot 
method  at  best  cannot  produce  an  atmosphere  containing  more  than  4 
per  cent,  of  sulphur  dioxid,  whereas  it  is  theoretically  possible  to  charge 
a  confined  space  with  a  higher  percentage  of  the  gas  by  means  of  the 
furnace.  In  practice  this  is  not  possible  without  burning  a  great  excess 
of  sulphur  and  by  expending  a  very  long  time,  for  the  reason  that  the 
fumes  first  entering  mix  with  the  air  and  as  the  gas  continues  to  flow 
into  the  space  it  displaces  about  an  equal  quantity  of  this  mixture  of 
sulphur  dioxid  and  air,  so  that,  as  a  matter  of  fact,  in  actual  practice 
only  about  2%  to  6  per  cent,  of  the  gas  is  usually  obtained  in  the  holds 
of  vessels  by  the  sulphur  furnace. 

It  is  advisable  in  using  the  sulphur  furnace  to  arrange  the  pipe  ad- 
mitting the  gas  into  the  room  as  near  the  floor  as  possible.  In  disinfect- 
ing the  holds  of  vessels  the  pipe  is  usually  let  down  the  hatchway  until 
it  is  near  the  bilge.  The  heavy  gas  collects  at  the  bottom  and  gradually 
ascends,  displacing  the  air,  so  that  it  is  important  to  allow  an  opening 


GASEOUS  DISINFECTAATTS— FUMIGATION 


1143 


of  some  sort  for  the  exit  of  the  air  near  the  top  of  the  compartment  that 
is  being  disinfected.  This  opening  should  not  be  closed  until  the  gas 
escapes  freely. 

The  Kinyoun-Francis  furnace  consists  of  an  iron  pan  upon  which 
the  sulphur  is  burned.  Under  this  pan  is  a  firebox  with  ashpit  and  nec- 
essary drafts.  The  firebox  is  designed  to  hold  a  light  fire  of  wood  or 
shavings  and  is  intended  to  heat  the  sulphur  pan  sufficiently  to  ignite 
the  sulphur  when  thrown  upon  it  at  the  beginning  of  the  operation.  This 
part  of  the  apparatus  is  unnecessary,  as  the  sulphur  may  be  ignited 
more  simply  by  means  of  some  alcohol,  turpentine,  or  kerosene  on  waste, 
or  a  few  live  coals.  \^Qien  once  lighted  there  is  no  trouble  in  keeping 
the  sulphur  burning. 


oouai.E    euLPHui^  iFURNAce 
Fig.  168. — Section  through  Double  Sulphur  Furnace. 


The  air  enters  at  A,  Fig.  168,  through  a  valve  arranged  to  regulate 
the  amount  of  flow.  It  then  passes  over  the  burning  sulphur  in  the 
direction  shown  by  the  course  of  the  arrows  to  the  fan.  Fumes  are 
compelled  to  take  a  devious  course  around  the  baffle  plates  and  angle 
irons,  as  shown  in  the  drawing,  in  order  to  insure  complete  combustion 
and  to  arrest  sparks.  From  B  the  fumes  are  sucked  to  the  fan,  which 
is  actuated  by  a  steam  engine  or  electric  motor,  and  which  forces  the 
gas  through  the  pipes  to  the  place  to  be  disinfected, 

Eunning  the  fan  at  too  high  a  speed  may  cause  overheating  of  the 
pipes  or  the  carrying  over  of  sparks  ol  burning  sulphur.  The  proper 
amount  of  air  should  be  carefully  regulated  so  as  to  obtain  complete 
combustion  and  the  maximum  amount  of  sulphur  dioxid  gas. 

The  pipe  conducting  the  fumes  from  the  sulphur  furnace  to  the 
compartment  to  be  disinfected  gives  a  certain  amount  of  trouble.  It  is 
apt  to  become  clogged  with  sulphur  which  sublimes  in  the  cooler  parts. 


1144  CHEMICAL  AGENTS  OF  DISINFECTION 

Ordinarily  this  pipe  must  be  from  G  to  8  inches  in  diameter  and  may 
be  made  of  smooth  galvanized  iron  and  the  joints  made  tight  with  sev- 
eral layers  of  canvas  saturated  and  coated  with  some  fireproof  paint. 
Eubber  hose  of  this  size  is  very  expensive  and  soon  vulcanizes. 

No  arrangement  is  made  in  this  form  of  apparatus  for  adding  water 
vapor  to  the  sulphur  fumes,  which  is  necessary  to  obtain  germicidal 
action.  As  a  rule  the  holds  of  wooden  vessels,  in  which  sulphur  fumiga- 
tion is  so  much  used,  are  usually  so  damp  that  the  addition  of  more 
moisture  is  not  necessary. 

The  Clayton  furnace  is  a  more  compact  apparatus  than  that  just 
described.  The  sulphur  dioxid  is  passed  through  a  series  of  tubes  sur- 
rounded by  water,  an  arrangement  corresponding  in  all  respects  to  the 
tubular  condenser  of  a  low-pressure  steam  engine.  The  Clayton  furnace 
is  furnished  with  a  Eoot  blower,  and  has  the  advantage  that  a  compara- 
tively large  volume  of  sulphur  dioxid  may  be  pumped  rapidly  through 
pipes  of  small  >caliber  without  fear  of  overheating  or  fire.  These  fur- 
naces are  being  installed  upon  ships  for  the  purpose  of  fumigation  at 
port  and  during  the  voyage  for  the  destruction  of  rats,  mice,  and  vermin. 
It  is  also  an  efficient  fire  extinguisher. 

A  portable  sulphur  furnace  is  a  useful  apparatus  in  municipal  work, 
particularly  in  the  fumigation  of  sewers,  warehouses,  stables,  barns, 
and  similar  large,  rough  structures  infested  with  vermin.  This  form 
of  furnace  was  used  in  the  fight  against  rats  in  the  sewers  of  San  Fran- 
cisco in  the  anti-plague  campaign. 

Hydrocyanic  Acid  G-as. — Hydrocyanic  acid  gas  is  a  very  powerful 
insecticide,  but  a  weak  germicide.  It  appears  to  be  effective  against  or- 
ganisms no  hardier  than  those  of  diphtheria  and  typhoid.  On  account 
of  its  extremely  poisonous  nature  it  has  a  very  limited  place  in  practical 
public  health  work  for  the  destruction  of  bacteria.  Hydrocyanic  acid 
gas  is  useful  in  the  treatment  of  stables,  granaries,  outhouses,  compart- 
ments of  ships,  sleeping-cars,  day  coaches,  and  similar  isolated  or  unin- 
habited places  for  the  destruction  of  vermin. 

Creel  ^  found  that  powdered  potassium  cyanid  facilitates  the  evolu- 
tion of  the  gas,  which  is  lighter  than  air  and  rises;  it,  therefore,  per- 
meates a  space  more  quickly  than  SO2.  Creel  also  found  that  hydro- 
cyanic acid  gas  does  not  destroy  bacteria.  Creel  and  Faget  ^  found  that 
four  ounces  of  potassium  cyanid  per  1,000  cubic  centimeters  is  sufficient 
to  kill  mosquitoes  in  15  minutes;  five  ounces  per  1,000  cubic  centimeters 
kills  bedbugs  and  roaches  in  one  hour,  lice  in  two  hours;  two  and  one- 
half  ounces  per  1,000  c.  c.  kills  fleas  in  15  minutes  (see  p.  215). 

Chlorin. — Chlorin  is  a  germicide  of  considerable  but  uncertain  power. 

1  Creel,  R.  H.,  Public  Health  Reports,  Vol.  XXX,  No.  49,  Dec.  3,  1915,  p.  3537. 
Creel,  R.  H.,  and  Faget,  F.  M.,  Public  Health  Reports,  Vol.  XXXI,  No.  23, 
June  9,  1916,  p.  1463. 


GASEOUS  DISINFECTANTS— FUMIGATION  1145 

It  has  little  practical  usefulness  owing  to  its  poisonous  and  destructive 
action.  Both  in  its  free  state  and  its  watery  solution  it  has  active 
deodorizing  properties.  Moisture  is  necessary  for  the  disinfecting  action 
of  chlorin  gas.  At  best  chlorin,  like  all  gases,  is  but  a  surface  disin- 
fectant. 

Chlorin  is  an  extremely  irritating  gas,  and  great  care  must  be  ob- 
served in  its  employment,  for  the  inhalation  of  very  weak  proportions 
of  the  gas  produces  serious  irritation,  resulting  in  spasm  of  the  larynx, 
bronchitis,  and  even  in  death.  Chlorin  is  heavier  than  air  (sp.  gr.  2.47) 
and  tends  to  fall.  Therefore  the  vessel  generating  the  gas  should  be 
placed  in  an  elevated  position  in  order  to  obtain  anything  like  effective 
diffusion.  Carpets,  curtains,  and  fabrics  generally  are  injured  by  its 
action,  and  the  element  is  a  very  active  bleaching  agent. 

The  germicidal  action  of  chlorin  depends  upon  its  great  affinity  for 
hydrogen.  So  strong  is  this  affinity  that  it  combines  with  the  hydrogen 
of  water  in  the  presence  of  light,  liberating  the  oxygen  in  its  nascent 
state,  thereby  enabling  the  oxygen  to  exert  its  power  upon  organic  mat- 
ter. The  value  of  chlorin  as  a  deodorant  depends  upon  its  power  of 
decomposing  the  offensive  gases  of  decomposition  such  as  sulphuretted 
hydrogen  and  volatile  ammoniacal  compounds. 

The  most  convenient  method  of  generating  chlorin  gas  is  by  decom- 
posing 11/2  pounds  of  calcium  chlorid  with  6  ounces  of  strong  sul- 
phuric acid.  This  produces  sufficient  gas  for  the  disinfection  of  1,000 
cubic  feet  of  air  space,  or  the  gas  may  be  generated  from: 

Common  salt 8  ounces  (240  grams) 

Manganese  dioxid 2       "       (60      "     ) 

Sulphuric  acid 2       "       (60      "     ) 

Water 2      "       (  60      "     ) 

The  following  reaction  takes  place : 

2NaCl+Mn02+3H2S04=3NaH2S04+MnS0,+2H20+Cl2 

Mix  the  water  and  the  acid  together  and  then  pour  the  mixture  over 
the  salt  and  manganese  dioxid  in  a  glazed  earthenware  basin.  The 
basin  should  rest  on  sand  or  in  water. 

Fisher  and  Proskauer  have  shown  that  in  ordinary  dry  air  5.38  parts 
of  free  chlorin  per  1,000  cubic  feet  of  air  space  appear  to  be  necessary 
to  kill  microorganisms.  If  the  air  is  moist  only  0.3  per  cent,  by  volume 
in  each  1,000  cubic  feet  of  air  is  sufficient,  disinfection  being  completed 
in  5  to  8  hours. 

Free  chlorin  is  much  less  useful  than  sulphur  dioxid,  since  it  is  more 
difficult  to  control,  more  dangerous  to  manipulate,  and  more  destructive 
in  its  effects. 


1140  CHEMICAL  AGENTS  OF  DISINFECTION 

Chlorin  gas  liberated  from  a  compressed  liquid  state  is  used  for  the 
disinfection  of  water   (page  905). 

Oxygen. — The  disinfecting  power  of  oxygen  depends  largely  upon  the 
physical  state  in  which  it  exists.  For  instance,  oxygen  in  the  air  has 
comparatively  feeble  germicidal  properties  when  compared  to  nascent 
oxygen  or  ozone.  The  germicidal  action  of  oxygen  depends  upon  its 
very  active  property  of  combining  chemically  with  the  albuminous  mat- 
ter of  the  cell  protoplasm.  The  oxidizing  properties  of  this  element 
partly  explain  the  purifying  action  of  fresh  air.  The  germicidal  prop- 
erty of  oxygen  is  greatly  accelerated  by  the  actinic  rays  in  sunlight. 
While  most  bacteria  require  the  free  oxygen  of  the  air  for  their  growth 
and  multiplication,  there  is  a  large  class  of  organisms  (the  anaerobes) 
to  which  the  oxygen  of  the  air  acts  like  a  poison  or  strong  antiseptic. 

Ozone. — Ozone  is  an  allotropic  form  of  oxygen  containing  three  atoms 
of  that  element  instead  of  two.  In  sufficient  concentration  it  is  a  pow- 
erful germicide  and  has  lately  "been  found  of  practical  use  in  the  steriliza- 
tion of  water  on  a  large  scale  for  the  use  of  cities  and  towns.  It  has 
also  been  used  for  the  sterilization  of  bandages  and  other  objects.  There 
is  not  sufficient  ozone  in  the  air  normally  to  exert  any  appreciable  oxidiz- 
ing or  disinfecting  properties.  It  requires  at  least  13  parts  per  million 
in  the  atmosphere  to  exert  a  definite  effect  upon  bacteria ;  even  then  the 
action  is  not  penetrating.  Such  quantities  are  harmful  to  man.  (See 
pages  667  and  897.)    • 

Ozone  may  be  used  to  destroy  odors  of  organic  origin  due  to  sub- 
stances that  may  be  oxidized,  such  as  the  odors  in  dissecting  rooms, 
animal  pens,  and  like  places. 


LIQUID  DISINFECTANTS 

These  consist  of  substances  either  in  solution  or  suspension.  An 
enormous  number  of  such  disinfectants  have  been  exploited,  but  to  be 
of  practical  value  they  must  not  only  be  strongly  germicidal,  but  must 
also  meet  the  many  exacting  requirements  of  general  practice.  Such  sub- 
stances are  few  in  number. 

Almost  any  chemical  substance  under  one  condition  or  another  has 
the  power  to  retard  the  development  or  destroy  the  activity  of  microbial 
life.  We  need  only  mention  the  well-known  power  of  common  salt  or 
of  sugar,  both  of  which  in  sufficient  concentration  prevent  the  processes 
of  fermentation  and  putrefaction.  In  weaker  dilutions  these  same  sub- 
stances, on  the  contrary,  favor  growth  of  almost  all  the  known  bacteria. 

The  undeserved  reputation  of  many  chemical  substances  depends 
more  upon  their  vile  odor  or  judicious  advertising  than  upon  actual 
efficiency.    Only  those  substances  that  have  proven  their  worth  by  scien- 


LIQUID  DISINFECTANTS  1147 

tific  tests  and  shown  themselves  to  be  trustworthy  in  actual  practice 
will  be  discussed.     (See  page  1117.) 

Methods  of  Using  Chemical  Solutions. — There  are  various  ways  of 
applying  chemical  solutions  for  disinfecting  purposes.  No  method  is 
trustworthy  that  does  not  thoroughly  wet  the  object  with  the  solution, 
so  that  there  may  be  direct  contact  between  the  substance  in  solution 
and  the  germs  that  are  to  be  destroyed. 

As  a  rule  this  may  best  be  accomplished  by  immersing  the  infected 
object  in  the  solution.  When  this  is  not  practicable  the  solution  must 
be  applied  to  the  object.  A  favorite  way  of  applying  disinfecting  solu- 
tions to  surfaces,  such  as  walls,  ceilings,  the  holds  of  ships  and  other 
rough  structures,  is  by  means  of  a  hose.  The  pressure  is  supplied  either 
by  elevating  the  tank  containing  the  solution  or  by  means  of  a  pressure 
pump.  As  bichlorid  of  mercury  is  practically  the  only  disinfectant  used 
in  this  way,  the  pump  should  be  made  of  iron  and  have  no  copper,  brass, 
or  steel  piarts  exposed  to  the  corroding  action  of  the  bichlorid  of  mercury. 

In  applying  the  disinfecting  solution  to  the  surfaces  of  a  room  or  the 
hold  of  a  ship  the  operator  should  begin  at  one  corner  of  the  ceiling, 
wetting  that  first,  and  then  go  over  every  portion  of  the  walls  system- 
atically, from  above  downward.    The  floor  comes  last. 

Solutions  thus  applied  remain  but  a  short  time  in  contact  with  the 
surfaces  to  be  disinfected.  It  is  therefore  an  advantage  to  have  the  solu- 
tion hot  and  strong  and  to  have  sufficient  pressure,  in  order  to  obtain  the 
mechanical  cleansing  effect  produced  by  a  vigorous  stream. 

Another  method  of  applying  disinfecting  solutions  to  surfaces  is  by 
means  of  mops,  brooms,  and  the  like. 

The  pulverizer  is  very  popular  in  France  for  the  disinfection  of  walls 
and  other  surfaces  with  liquid  disinfectants.  The  apparatus  for  this  pur- 
pose consists  of  a  metal  cylinder  fitted  with  a  simple  force  pump  which 
compresses  the  air  in  the  reservoir.  The  solution  does  not  come  in  con- 
tact with  the  pump.  The  current  of  air  driven  through  one  tube  sucks 
the  solution  through  the  other  and  sprays  it  from  the  nozzle  in  a  nebulous 
cloud,  similar  in  principle  to  the  well-known  hand  atomizers.  It  is  easy 
to  demonstrate,  by  using  a  colored  solution  upon  a  white  wall  or  sheet, 
that  a  liquid  sprayed  in  this  way  does  not  wet  the  entire  surface.  The 
method  is  therefore  an  unscientific  and  unreliable  one  when  used  with 
a  non-volatile  chemical. 

Germicidal  solutions  are  much  more  potent  when  used  hot. 

Bichlorid  of  Mercury. — HgClg,  bichlorid  of  mercury  or  mercuric 
chlorid,  commonly  called  corrosive  sublimate,  is  one  of  our  most  valu- 
able and  potent  germicides.  It  destroys  all  forms  of  microbial  life  in 
relatively  weak  solutions.  It  kills  both  germs  and  their  spores. .  It  is 
not  a  deodorant. 

The  disadvantages  of  bichlorid  of  mercury  are  that  it  corrodes  metals. 


1148  CHEMICAL  AGENTS  OF  DISINFECTION 

forms  insoluble  and  inert  compounds  with  albuminous  matter,  and  is 
very  poisonous.  These  disadvantages  place  distinct  limitations  upon  its 
use. 

Mercuric  chlorid  (HgClg)  is  a  white,  crystalline  substance  of  heavy 
specific  gravity  (5.43).  It  volatilizes  somewhat  more  readily  than  mer- 
curous  chlorid  (calomel),  even  at  room  temperature.  On  account  of 
this  property  caution  should  be  observed  to  remove  bichlorid  solutions 
from  living-rooms,  some  instances  of  poisoning  having  been  traced  to 
this  neglect.  It  is  therefore  well  to  follow  bichlorid  with  clear  water  and 
a  cleansing  is  always  in  order. 

Bichlorid  of  mercury  will  dissolve  in  16  parts  of  cold  water  and  3 
parts  of  boiling  water.  As  it  is  not  readily  soluble  in  water,  it  is  con- 
venient to  keep  a  saturated  alcoholic  solution  on  hand  and  use  this  to 
make  the  watery  solution.  A  25  per  cent,  solution  may  readily  be  made 
in  alcohol,  and  by  the  addition  of  hydrochloric  acid  or  ammonium  chlorid 
this  solution  keeps  well  without  precipitation.  As  this  method  would 
be  rather  expensive  for  making  up  the  large  quantities  required  in  flush- 
ing the  holds  of  ships  or  other  extensive  surfaces  a  little  device  pointed 
out  by  Geddings  will  be  found  serviceable.  This  consists  in  weighing  out 
the  correct  quantity  of  the  bichlorid,  which  is  placed  in  a  canvas  bag, 
and  this  is  hung  from  the  faucet  so  that  the  water  will  run  through  it 
into  the  tank  or  receptacle  holding  the  solution. 

The  solution  of  bichlorid  of  mercury  is  facilitated  by  the  presence 
of  hydrochloric  acid  or  a  chlorid  such  as  ammonium  chlorid  or  common 
salt.  Twice  the  weight  of  these  substances  should  be  added  to  the  quan- 
tity of  bichlorid  used.  If  the  solution  is  to  be  pumped  or  otherwise 
come  in  contact  with  metals  it  is  better  to  use  the  salt  than  the  acid, 
because  the  acid  solution  of  bichlorid  is  very  destructive  to  the  metal 
parts  of  the  pump  and  to  the  couplings  and  nozzle  of  the  hose,  particu- 
larly if  this  is  made  of  copper  or  brass.  Sea-water  contains  about  4  j)er 
cent,  of  salt,  and  is  well  suited  for  making  bichlorid  solutions.  It  is 
extensively  used  at  seaport  quarantine  stations  for  this  purpose. 

Laplace  first  pointed  out  that  the  addition  of  a  small  amount  of  an 
acid  to  the  solution  of  bichlorid  of  mercury  greatly  increases  its  effi- 
ciency, and  by  lessening  the  formation  of  insoluble  albuminates  also 
increases  its  power  of  penetration.  This  was  later  denied  by  Kronig  and 
Paul,  who  assert  that  the  addition  of  sodium  chlorid  to  a  watery  solu- 
tion of  bichlorid  diminishes  its  power.  They  found  that  potassium 
chlorid  or  hydrochloric  acid  has  the  same  effect. 

The  germicidal  action  of  bichlorid  solution  seems  to  depend  upon 
the  reaction  which  takes  place  between  the  salt  of  mercury  and  the  myco- 
protein  of  the  germ.  Geppert  has  shown  that  in  the  reaction  which  takes 
place  between  the  bichlorid  of  mercury  and  the  spores  of  anthrax  the 
vitality  of  the  latter  may  seem  to  be  lost,  but  that  the  bichlorid  may  bo 


COAL-TAE  AND  ITS  PRODUCTS  1149 

precipitated  from  its  combination  by  the  action  of  ammonium  sulphid, 
thus  restoring  the  viability  of  the  spore. 

Bichlorid  of  mercury  is  decomposed  by  lead,  tin,  copper,  and  other 
metals,  and  therefore  should  not  be  made  or  kept  in  metal  receptacles. 
Lead  pipes  are  rendered  brittle  and  worthless.  Care  must  therefore  be 
exercised  in  using  this  solution  about  water-closets  and  house  plumbing. 

Corrosive  sublimate  is  precipitated  in  alkaline  fluids  containing  albu- 
minous substances.  The  precipitate  consists  of  insoluble  and  inert  com- 
pounds; therefore  corrosive  sublimate  should  not  be  used  for  the  disin- 
fection of  media  containing  much  organic  matter,  particularly  Avhcn 
the  reaction  is  alkaline.  It  is  not  M'ell  suited  to  the  disinfection  of 
sputum  and  feces,  for  it  forms  an  albuminate  which  retards  penetration. 
It  also  unites  chemically  with  sulphids  and  the  caustic  alkalies,  so.  that 
it  should  not  be  employed  as  a  disinfectant  when  these  substances  are 
present  in  any  considerable  amount. 

To  diminish  the  danger  from  accidents  in  households  and  hospitals 
bichlorid  solutions  should  be  colored  with  permanganate  of  potash  or 
indigo  or  one  of  the  anilin  dyes. 

Bichlorid  of  mercury  is  usually  used  in  the  proportion  of  1  to  500  or 
1  to  1,000.  A  solution  of  1  to  1,000  is  ample  for  the  destruction  of 
all  the  non-spore-bearing  bacteria,  provided  the  exposure  is  continued 
not  less  than  half  an  hour  and  direct  contact  is  assured.  To  assure  this 
contact  a  longer  time  should  be  allowed  in  practice.  Many  bacterial 
cells  are  killed  almost  at  once  when  brought  into  direct  contact  with  a 
solution  of  this  strength,  and  the  great  majority  perish  within  15  min- 
utes. The  extra  time  allows  for  penetration  and  provides  a  factor  of 
safety.  Warm  solutions  are  much  more  potent  than  cold.  For  spores  a 
solution  of  1  to  500  is  necessary  and  an  exposure  of  not  less  than  one 
hour. 

For  practical  work  fhe  solution  may  be  made  as  follows: 

Corrosive   sublimate    1  dram     |     1  gram 

Water   1  gallon    |     1  liter 

Mix  and  dissolve. 

This  is  approximately  a  1  to  1,000  solution.  One  ounce  of  this 
solution  contains  very  nearly  half  a  grain  of  corrosive  sublimate. 


COAL-TAR   AND    ITS   PRODUCTS 

Coal  Tar  Creosote. — Creosote  is  a  highly  complex  refractile  liquid 
obtained  from  the  destructive  distillation  of  wood  or  coal.  Wood-tar 
creosote  for  medicinal  use  is  obtained  from  beechwood;  it  is  a  complex 
mixture  of  phenoloid  bodies,  the  proportions  of  which  differ  according  to 


1150  CHEMICAL  AGENTS  OF  DISINFECTION 

the  modes  of  distillation  and  purification.  It  contains  phenols,  cresols, 
and  higher  homologs.  Coal-tar  creosote,  sometimes  called  creosote  oil, 
contains  that  portion  of  the  distillate  from  coal-tar  intermediate  between 
crude  naphtha  on  the  one  hand  and  pitch  on  the  other.  Coal-tar  creosote 
contains  phenols,  cresols,  and  higher  phenoloid  bodies,  also  naphthalene 
and  other  solid  hydrocarbons,  as  well  as  pyridin  and  other  bodies  of  basic 
character.  Creosotes  vary  in  composition,  and  owe  their  germicidal 
properties  to  the  phenol  and  cresols  which  they  contain.  They  are  sel- 
dom used  as  such,  but  form  bases  of  many  commercial  disinfectants  after 
purification  or  the  addition  of  alkalis  or  soaps.  It  is  the  creosote  from 
coal-tar,  and  not  wood-tar,  that  is  used  as  a  germicide  in  public  health 
work. 

^ale  ^  has  shown  that  the  coal-tar  disinfectants  of  the  phenoloid 
group  are  considerably  less  toxic  than  either  phenol  or  the  cresols,  but 
they  are  not  harmless,  nonpoisonous  substances  as  sometimes  indicated 
by  the  commercial  labels.  On  an  average  the  disinfectants  of  the  pheno- 
loid group  have  a  toxicity  equal  to  about  15  or  20  per  cent,  of  that  of 
phenol. 

Carbolic  Acid. — ^Carbolic  acid  is  a  very  useful  disinfecting  substance 
with  a  wide  range  of  application.  It  should  not  be  depended  upon  to  kill 
spores.  As  it  does  not  coagulate  albuminous  matter  as  actively  as 
corrosive  sublimate  it  may  be  used  for  the  disinfection  of  soiled. clothing 
and  bedding,  as  well  as  for  excreta  and  sputum. 

Carbolic  acid  is  a  popular  term  for  an  ill -defined  mixture  consisting 
largely  of  phenol  and  phenolic  bodies.  Crude  carbolic  acid  was  discov- 
ered by  Eunge  (1834)  in  coal  tar.  It  is  a  nearly  colorless,  or  reddish  to 
reddish -brown  liquid,  turning  darker  on  exposure  to  air  and  light.  It 
has  a  strong  creosote-like  odor,  with  benumbing,  blanching,  and  caustic 
effects  upon  the  skin  and  mucous  membrane.  Crude  carbolic  acid  is  a 
mixture  of  phenols  and  cresols,  with  coloring  matter  and  impurities. 
Carbolic  acid  is  often  used  as  a  synonym  for  phenol ;  in  fact,  the  British 
Pharmacopoeia  recognizes  the  name  "Acidum  earbolicum,"  but  uses 
"phenol"  as  the  English  name  for  this  substance.  In  America  the  term 
"carbolic  acid"  is  restricted  to  the  crude  mixture  of  phenols  and  cresols ; 
whereas  phenol  is  a  definite  chemical  substance  CgHsOH  (See  Phenol). 

Crude  carbolic  acid  is  soluble  in  15  parts  of  water  at  15°  C,  making 
about  a  6  per  cent,  solution.  The  undissolved  portion  should  not  ex- 
ceed 10  per  cent,  of  the  volume  of  the  carbolic  acid.  Carbolic  acid  is  a 
very  useful  disinfecting  substance  with  a  wide  range  of  applicability. 
The  cresols  contained  in  carbolic  acid  have  a  higher  germicidal  value 
than  pure  phenol  itself.  The  commercial  carbolic  acid  also  contains 
hydrocarbons,  and  other  impurities  of  tar  oil  which  are  totally  lacking 
in  bactericidal  properties. 

^Hyg.  Lab.  Bull.  No.  88.— U.  S.  P.  H.  S.,  1913. 


COAL-TAR  AXD  ITS  PEODUCTS  1151 

Crude  carbolic  acid  dissolves  in  water  with  some  difficulty  and  should 
therefore  be  thoroughly  mixed.  It  is  used  in  solutions  of  2.5  to  5  per 
cent.;,  in  which  strength  it  may  be  used  for  the  destruction  of  non-spore- 
bearing  bacteria.  A  5  per  cent,  solution  is  not  dependable  against  spores. 
Warm  or  hot  solutions  are  much  more  effective  than  cold.  It  should  be 
remembered  that  crude  carbolic  acid  (coefficient  3.75)  has  a  higher 
germicidal  potency  than  pure  phenol  (coefficient  1.0).  Crude  carbolic 
acid  is  commonly  used  for  rough  disinfecting  purposes,  such  as  floors, 
stables,  barns,  outhouses,  animal  pens,  etc. 

Phenol. — Phenol,  CgHgOH,  has  the  chemical  structure  of  an  alcohol, 
and  is  the  chief  constituent  of  carbolic  acid.  Pure  phenol  crystallizes 
in  long  colorless  needles;  commercial  phenol  forms  a  crystalline  mass 
which  turns  reddish  in  time,  and  in  contact  with  moist  air  deliquesces 
to  a  brown  liquid.  It  has  a  penetrating  odor  and  strong  burning  taste, 
and  is  a  corrosive  poison.  It  is  soluble  in  10.6  parts  of  water  at  25°  C, 
very  soluble  in  ether,  alcohol,  chloroform,  benzin,  carbon  disulphid, 
glycerin,  fixed  and  volatile  oils. 

Phenol  when  dissolved  in  alcohol  or  ether  loses  in  germicidal  value; 
the  addition  of  0.5  per  cent,  of  hydrochloric  acid  aids  its  activity. 

McClintock  and  Ferry  ^  have  shown  that  the  la^ge  majority  of  the 
coal-tar  disinfectants  (carbolic  acid,  cresols^  and  the  like)  do  not  destroy 
the  virulence  of  vaccine  virus  in  one-half  per  cent,  solutions  at  five  hours' 
exposure,  while  with  this  strength  and  length  of  time  these  disinfectants 
would  destroy  practically  all  non-spore-bearing  bacteria.  The  inference, 
therefore,  is  allowable  that  this  class  of  disinfectants  is  not  safe  to  use 
for  such  diseases  as  smallpox  or  any  other,  the  cause  of  which  is  not 
known. 

The  fact  that  carbolic  acid  and  phenol  do  not  actively  coagulate 
albuminous  matter  renders  them  suitable  to  the  disinfection  of  excreta 
and  organic  matters  generally.  They  are  not  destructive  to  fabrics,  colors, 
metals,  or  wood  in  the  strengths  used,  and  therefore  may  be  employed 
for  the  disinfection  of  a  great  variety  of  objects.  Crude  carbolic  acid, 
although  it  has  a  stronger  germicidal  power  than  pure  phenol,  has  the 
disadvantage  of  having  a  more  pungent  and  penetrating  odor  and  leaves 
a  deposit  of  coal-tar  oils  and  other  impurities. 

There  has  been  much  disparagement  of  carbolic  acid  because  labora- 
tory tests  have  clearly  demonstrated  that  it  cannot  always  be  depended 
upon  to  kill  spores.  This  limits  but  does  not  destroy  its  usefulness,  espe- 
cially as  the  great  majority  of  the  epidemic  diseases  of  man  are  due  to 
non-spore-bearing  bacteria. 

The  time  of  exposure  to  a  three  or  five  per  cent,  solution  should  be 

^McClintock,  Chas.  T.,  and  Ferry,  N.  S. :  "The  Resistance  of  Smallpox 
Vaccine  to  the  Coal  Tar  Disinfectants,"  Jour,  of  the  Am.  Pub.  Health  Assn., 
Vol.  I.  No.  6,  June.  1911,  pp.  418-420. 


1152  CHEMICAL  AGENTS  OF  DTSINFECTION 

jiot  less  than  one-half  an  liour.  Fabrics  are  usually  imnicrscd  for  one 
hour. 

The  Introduction  of  a  halogen  atom  into  the  benzol  ring  greatly  in- 
creases the  germicidal  power  of  the  phenols,  cresols  and  naphthols,  while 
at  the  same  time  the  toxicity  of  these  substances  is  diminished.  Thus 
Bechhold  and  Ehrlich  ^  have  shown  that  tri-brom-y8-naphthol  and  tri- 
chlor-/3-naphthol  are  very  powerful  germicides,  but  practically  odorless, 
and  not  very  poisonous. 

The  Cresols. — By  far  the  majority  of  the  disinfectants  sold  to  the 
public  are  mixtures  of  varying  quantities  of  phenolic  bodies,  especially 
the  cresols,  with  inert  tar  oils  and  an  emulsifying  agent  such  as  soap 
or  tar,  and  sometimes  rosin,  gelatin,  or  dextrin.  These  substances  all 
possess  a  smell  distinctive  of  carbolic  acid  and  are  effective  germicides. 
The  cresols  C6H4(CH3)0H,  have  the  advantage  over  carbolic  acid  or 
pure  phenol  in  that  they  readily  form  beautiful  emulsions,  have  a  higher 
germicidal  value,  and  are  less  poisonous.  It  has  already  been  pointed 
out  that  while  emulsions  may  be  more  potent  germicides  than  solutions, 
on  the  other  hand  they  lack  the  power  of  penetration. 

Cresol  is  prepared  from  coal-tar  by  collecting  the  distillates  coming 
over  between  140°  C.  and  220°  C,  and  then  purifying  these  distillates 
by  treatment  with  solution,  of  sodium  hydroxid  and  hydrochloric  acid. 
Cresol  is  a  mixture  of  the  three  isomeric  cresols  obtained  from  coal- 
tar  and  freed  from  phenol,  hydrocarbons,  and  water.  It  is  also  known 
as  cresylic  acid. 

Creso  ^  consists  of  a  mixture  of  ortho-,  meta-,  and  paracresols.  Meta- 
cresol  is  a  liquid;  the  other  two  are  solid  crystalline  bodies  having  a 
low  melting  point.  These  cresols  are  found  in  commercial  carbolic  acid. 
The  cresol  group  forms  the  next  higher  homolog  to  phenol,  one  atom  of 
hydrogen  being  replaced  in  the  latter  by  the  methyl  radicle,  CHg.  The 
cresols  are  very  insoluble  in  water.  Their  solution  may  be  facilitated 
by  the  use  of  alcohol  or  glycerin.  Cresol  is  a  clear  or  pink-colored 
syrupy  liquid.  It  is  soluble  to  the  extent  of  about  2i/2  per  cent,  in  water. 
It  is  somewhat  less  poisonous  than  carbolic  acid;  its  uses  are  the  same. 
It  is  an  effective  germicide  in  a  1  per  cent,  solution. 

Liquor  Ceesolis  Compositus. — Liquor  cresolis  compositus  of  the 
U.  S.  Pharmacopoeia  is  a  substitution  compound  for  lysol  and  consists 
of  cresol,  500  gm. ;  linseed  oil,  350  gm. ;  potassium  hydroxid,  80  gm. ;  and 
water  sufficient  to  make  1,000  gm.  This  officinal  mixture  makes  a  clear 
solution  in  water.    The  solution  is  intended  as  a  substitute  for  the  many 

^Bechhold,  H.:  Ztschr.  f.  Hyg.  u.  Infektionskrankh.,  1909,  Bd.  64,  p.  113. 
Bechhold,  H.  and  Ehrlich,  P.:  Hoppe-Seyler's  Ztschr.  f.  physiol.  Chem.,  1906, 
Bd.  XLVII,  Hefte  2  und  3,  p.   173. 

^  Trikresol  is  a  trade  name.  It  is  the  same  substance  as  "Cresol"  of  the 
U.  S.  Pharmacopoeia. 


C0AL-TA17  AND  ITS  PRODUCTS  1153 

commercial  preparations  of  cresol  on  the  market.  It  has  practically  the 
same  uses  as  the  trikresol  of  commerce. 

lysol. — Lysol  is  a  brown,  oily-looking,  clear  liquid  with  a  creosote-like 
odor.  It  is  made  by  dissolving  a  fraction  of  tar  oil  which  boils  between 
190°  and  200°  C.  in  fat,  and  subsequently  saponifying  by  the  addition 
of  alkali  in  the  presence  of  alcohol.  It  contains  50  per  cent,  cresols,  espe- 
cially meta-  and  paracresols,  and  50  per  cent,  of  a  strong  concentrated 
potassium  soap  made  with  linseed  oil.  The  soap  contains  68  per  cent,  of 
fatty  acids.  Lysol  is  miscible  with  water,  forming  a  clean  saponaceous, 
frothy  liquid.  It  is  more  powerful  as  a  germicide  than  phenol,  and  is 
usually  used  in  1  per  cent,  solution.  It  has  a  carbolic  coefficient  of  2.13 
without  organic  matter  and  1.87  with  organic  matter. 

Creolin. — Creolin  is  a  proprietary  preparation  patented  by  Pearson 
and  consists  of  an  emulsion  of  cresols  and  certain  other  products  con- 
tained in  tar  oil,  with  rosin  soap.  Many  other  similar  preparations  are 
on  the  market,  such  as  cresolin,  cyllin,  disinfectol,  sanatol,  izal,  creo- 
sapol,  sylphonathol,  etc.  The  tar  oil  is  brought  into  solution  either  with 
rosin  soap  or  by  means  of  concentrated  sulphuric  acid.  Creolin  forms 
a  milky  emulsion  when  mixed  with  water.  It  is  used  in  1  or  2  per  cent, 
solution.  The  phenol  coefficient  is  3.25  without  organic  matter  and  2.52 
with  organic  matter. 

Aseptol. — Aseptol  is  a  33%  per  cent,  watery  solution  of  orthophenol- 
sulphonic  acid,  CgII^(S03pI)0H.  It  is  made  by  mixing  equal  parts  of 
phenol  and  concentrated  sulphuric  acid  in  the  cold;  if  warmed  para- 
sulphonic  acid  is  formed,  which  is  a  much  feebler  germicide  than  ortho- 
sulphonic  acid.  The  acidity  of  the  orthophenolsulphonic  acid  is  neutral- 
ized with  barium  carbonate. 

Aseptol  is  a  colorless  liquid  which  gradually  turns  yellowish,  when 
exposed  to  the  light,  with  a  weak  odor  of  phenol,  and  a  feeble  acid  reac- 
tion. It  is  miscible,  in  all  proportions,  with  water,  alcohol  and  glycerin. 
Orthophenolsulphonic  acid  gradually  changes  to  paraphenolsulphuric 
acid  in  watery  solution.  Aseptol  is  much  used  in  Germany  for  the  dis- 
infection of  barns,  outhouses,  stables,  and  woodwork,  soil,  and  the  purifi- 
cation of  rough  substances  generally.  It  is  usually  used  in  5  per  cent, 
solution.     In  this  strength  it  will  kill  anthrax  spores  in  24  hours. 

Asaprol. — Asaprol  is  the  calcium  salt  of  beta-naphthol  sulphonic  acid. 
It  is  made  by  warming  10  parts  of  beta-naphthol  with  8  parts  of  con- 
centrated sulphuric  acid  in  a  waterbath  until  a  clear  solution  is  obtained. 
It  is  then  diluted  with  water,  neutralized  with  calcium  carbonate,  filtered, 
and  the  filtrate  dried  to  a  reddish  powder.  This  powder  is  soluble  in  II/2 
parts  of  water  and  3  parts  of  alcohol.  It  turns  blue  upon  the  addition 
of  ferric  chloric!. 

Sanatol. — Sanatol  is  a  dark  fluid,  readily  miscible  with  water,  form- 
ing a  slight  turbidity.  It  is  made  from  20  parts  of  tar  oil,  containing 
38 


1154  CHEMICAL  AGENTS  OF  DTSTXFECTTOX 

phenols,  and  10  parts  of  90  per  cent,  sulphuric  acid,  and  dihitcd  with 
water  sufficient  to  make  100  parts. 

Solveol  and  Solutol. — Solveol  is  a  solution  of  sodium  cresolate  in 
excess  of  cresol.  Solutol  is  a  solution  of  cresol  in  excess  of  sodium 
cresolate. 

There  are  a  vast  number  of  other  commercial  disinfectants  of  similar 
nature  consisting  of  coal-tar  creosotes  in  combination  with  alkalis,  soaps, 
resins,  etc.,  such  as  chloronaphtholeum,  sulphonaphthol,  Ijacillol,  saprol, 
paracresol,  and  other  trade  names. 

Naphthols. — Naphthols  are  found  in  coal  tar  though  in  small  amount. 
They  have  a  high  germicidal  value  about  the  equal  of  phenols.  Naph- 
thol,  CiqH^OH,  is  a  hydroxyl  derivative  of  naphthalene;  a  and  j3  modi- 
fications are  known.  The  latter  is  of  especial  interest  as  a  germicide. 
jSTaphthol  itself  is  insoluble  in  water,  but  may  be  rendered  soluble  as  a 
sodium  salt,  or  may  be  emulsified  with  soaps  or  resin.  Naphthol  is  used 
more  as  a  medicinal  germicide  than  in  public  health  work.  Tri-chlor- 
beta-naphthol  is  much  more  germicidal,  but  less  toxic  than  phenol.^ 

Naphthalene. — Naphthalene,  C^oHg,  is  a  hydrocarbon  obtained  from 
coal  tar  and  purified  by  crystallization.  It  is  a  white,  shining  crystal- 
line substance,  having  a  strong  characteristic  odor  resembling  coal  tar, 
and  a  burning  aromatic  taste.  It  slowly  volatilizes  on  exposure  to  air. 
Naphthalene  is  insoluble  in  water,  but  soluble  in  alcohol.  It  burns  with 
a  smoky  flame. 

Naphthalene  has  antiseptic  properties  but  is  much  less  active  than 
either  the  cresols  or  the  phenols.  It  is  poisonous  to  most  fungi  and  prob- 
ably to  most  Insects.  Under  the  name  "tar  camphor"  it  has  largely  sup- 
planted true  camphor  as  a  means  of  preventing  the  deposition  by  moths 
of  eggs  in  woolen  clothing. 

Formalin. — Formaldehyd  in  solution  is  known  as  formalin.  This  is 
a  very  valuable  disinfectant  with  a  wide  range  of  usefulness  in  general 
practice.  It  is  superior  to  bichlorid  of  mercury  for  many  purposes, 
especially  as  its  action  is  not  seriously  retarded  by  the  presence  of  albu- 
minous matter.  Formalin  is  not  injurious  to  most  articles,  and  it  is 
not  very  poisonous.  It  is  a  true  deodorant.  The  more  I  work  with  for- 
maldehyd, both  in  solution  and  as  a  gas,  the  more  am  I  impressed  with 
its  trustworthiness. 

Formalin  consists  of  a  40  per  cent,  solution  of  the  gas  formaldehyd 
(HCHO)  dissolved  in  water.  The  liquid  is  a  clear  solution,  giving  off 
an  appreciable  odor  of  the  gas.  It  is  exceedingly  irritating,  but  not  espe- 
cially toxic.  Formalin  solutions  are  rather  unstable.  There  is  a  con- 
stant loss  by  evaporation  if  the  liquid  is  not  kept  well  corked,  and  in 
cold  weather  the  formaldehyd  polymerizes  and  precipitates  in  one  of 

^  See  "Phenol  und  seine  Derivate  als  Desinfektionsmittel,"  by  Kurt  Lauben- 
heimer.     Urban  and  Sclnvarzenbcrg,  Berlin,   1909. 


POTASSIUM  PEEMANGANATE  1155 

its  polymeric  forms — trioxy methylene.     For  the  description  and  discus- 
sion of  formaldehyd  see  page  1133. 

Hot  formalin  attacks  iron  and  steel,  hut  in  the  cold  has  no  appreciable 
effect.  It  does  not  attack  copper,  brass,  nickel,  zinc,  and  other  metal  sub- 
stances. It  causes  no  diminution  in  strength  of  textile  fabrics  and  has 
no  bleaching  or  other  deleterious  effects  upon  colors.  Formalin  renders 
leather,  furs,  and  skins  brittle  as  a  result  of  the  union  that  takes  place 
between  the  formaldehyd  and  the  organic  matter  of  these  articles,  and 
they  should  therefore  be  disinfected  by  another  process. 

A  10  per  cent,  solution  of  formalin  in  water  is  about  the  equivalent 
of  a  1  to  500  solution  of  bichlorid  of  mercury,  or  superior  to  a  o  per 
cent,  solution  of  carbolic  acid.  It  must  be  borne  in  mind  that  in  speak- 
ing of  a  solution  of  formalin  a  solution  is  meant  of  the  liquid  containing 
40  per  cent,  formaldehyd;  that  is,  a  1  per  cent,  solution  of  formalin 
would  contain  that  liquid  in  proportion  to  1  to  100,  but  would  contain 
the  substance  formaldehyd  in  the  proportion  of  1  to  250. 

Fecal  masses  are  deodorized  almost  instantly  by  a  small  quantity  of 
formalin,  and  are  disinfected  in  a  short  time  when  intimately  and  thor- 
oughly mixed  with  a  10  per  cent,  solution.  It  is  advisable  to  continue  the 
contact  one  hour  to  insure  complete  action. 

There  is  some  discrepancy  as  to  the  percentage  of  formalin  solution 
necessary  to  accomplish  trustworthy  disinfection  in  general  practice. 
Taking  into  account  the  deterioration  of  the  solution  with  age  and  allow- 
ing an  excess  as  an  element  of  safety,  a  10  per  cent,  solution  is  recom- 
mended. It  may  be  used  to  disinfect  urine,  excreta,  sputum,  and  other 
similar  substances. 

Potassium  Permanganate. — Potassium  permanganate  is  a  germicide 
of  undoubted  value,  but  of  very  limited  application  in  general  practice 
on  account  of  the  readiness  with  which  it  is  reduced  and  rendered  inert 
by  organic  matter.  Despite  its  limitations  it  ranks  high  on  the  list  of 
germicides  for  certain  definite  purposes,  more  particularly  in  surgical 
practice.  It  has  been  much  used  in  India  and  other  places  for  the  puri- 
fication of  water. 

Potassium  permanganate  (KMn04)  is  a  dark  purple,  crystalline 
substance  with  a  sweet,  astringent  taste.  A  few  crystals  impart  to  a 
large  quantity  of  water  a  rich  purple  tint  which  is  destroyed  by  organic 
matter  and  deoxidizing  agents.  It  is  soluble  in  16  parts  of  cold  and  2 
parts  of  boiling  water.  The  stain  produced  by  potassium  permanganate 
may  be  removed  by  a  solution  of  oxalic  acid,  muriatic  acid,  or  simple 
lemon  Juice. 

Potassium  permanganate  readily  gives  up  its  available  oxygen,  and 
it  is  the  free  nascent  oxygen  that  is  the  true  disinfecting  agent.  Stern- 
berg found  a  solution  of  1  to  833  sufficient  to  kill  pus  cocci  in  two  hours. 
Koch  found  that  a  5  per  cent,  solution  killed  spores  in  one  day.     Loef- 


1156  CHEMICAL  AGENTS  OF  DISINFECTION 

fler  found  that  the  bacillus  of  glanders  is  destroyed  in  two  minutes  by  a 
1  per  cent,  solution. 

Water  containing  organic  matier  may  be  purified  to  a  certain  extent 
and  rendered  palatable  by  adding,  drop  by  drop,  a  solution  of  perman- 
ganate until  the  pink  color  of  the  water  ceases  to  be  destroyed  after 
the  lapse  of  24  hours.  The  clear  liquid  may  then  be  decanted  and  used. 
Permanganate  'Used  in  this  way  does  not  reach  sufficient  concentration 
to  be  a  trustworthy  germicide. 

Lime. — Lime  is  one  of  the  best  and  cheapest  disinfecting  substances 
we  have.    It  is  usually  used  either  as  lime  or  chlorinated  lime. 

Lime,  or  quicklime,  is  a  very  caustic  substance  used  for  the  destruc- 
tion of  organic  matter  as  well  as  germ  life.  On  account  of  its  effi- 
ciency and  cheapness  it  is  a  valuable  addition  to  the  list  of  practical 
disinfectants.  Lime  or  calcium  oxid  (CaO)  is  one  of  the  alkaline 
earths.  It  is  not  so  caustic  as  the  alkalis,  having  less  affinity  for  water. 
It  is  obtained  by  calcining  native  calcium  carbonate  (CaCOg),  such  as 
chalk,  limestone,  or  marble,  by  which  the  carbon  dioxid  is  driven  off  and 
the  calcium  oxid  remains  behind.  Lime  as  such  requires  the  addition 
of  water  for  germicidal  purposes. 

Slaked  Lime. — Slaked  lime  or  calcium  hydroxid,  Ca(0II)2,  is  pre- 
pared by  adding  one  pint  of  water  to  two  pounds  of  lime.  The  lime 
absorbs  about  half  its  weight  of  water.  The  mass  becomes  heated  and 
the  air  escapes  from  the  pores  of  the  lime  with  a  hissing  noise.  The  result 
is  calcium  hydroxid  or  slaked  lime.  L^pon  exposure  to  the  air  the  slaked 
lime  will  absorb  still  more  water  and  also  carbon  dioxid,  converting  it 
into  calcium  carbonate,  which  is  inert  so  far  as  its  disinfecting  power  is 
concerned.    Freshly  slaked  lime  should  therefore  always  be  used. 

Whitewash  is  slaked  lime  mixed  with  water.  It  is  commonly  used 
for  the  disinfection,  sweetening,  and  brightening  of  the  walls  of  cellars, 
rooms,  barracks,  barns,  stables,  poultry-houses,  and  out-buildings  gen- 
erally. Whitewash  is  a  very  satisfactory  method  of  destroying  spore-free 
bacteria  that  may  have  lodged  upon  such  surfaces.  A  mordant  such  as 
glue  is  usually  added  to  whitewash  to  make  it  adhere. 

Milk  of  lime  is  slaked  lime  mixed  with  four  to  eight  times  its  volume 
of  water  to  the  consistency  of  a  thick  cream.  It  is  useful  for  the  disin- 
fection of  excreta  and  privy  vaults.  Air-slaked  lime  containing  the  inert 
carbonate  must  not  be  used  in  the  preparation  of  whitewash  or  milk  of 
lime,  freshly  slaked  lime  containing  calcium  hydroxid  being  necessary 
to  accomplish  disinfection.  Calcium  hydrate  is  mostly  insoluble  and  set- 
tles to  the  bottom ;  the  milk  of  lime  must  therefore  be  agitated  to  restore 
its  homogeneous  character  before  it  is  used.  Milk  of  lime  is  most  pow- 
erful when  freshly  prepared.  It  soon  changes  to  the  inert  carbonate, 
and  therefore  should  not  be  used  if  more  than  a  few  days  old  unless  care- 
fully protected  from  contact  with  the  air. 


LIME  1157 

Almost  all  laboratory  experiments,  while  differing  somewhat  in  cer- 
tain unimportant  particulars,  confirm  the  conclusions  of  the  early  in- 
vestigators as  to  the  great  practical  value  of  lime  as  a  germicide.  A  1 
per  cent,  watery  solution  of  the  hydroxid  kills  non-spore-bearing  bac- 
teria within  a  few  hours.  A  3  per  cent,  solution  kills  typhoid  bacilli  in 
one  hour.  A  20  per  cent,  solution  added  to  equal  parts  of  feces  or  other 
filth  and  mixed  with  them  will  disinfect  them  within  one  hour. 

Lime  is  particularly  valuable  in  the  disinfection  of  excreta.  The' 
lime  in  one  form  or  another  must  be  well  incorporated  with  the  mass 
and  enough  must  always  be  added  in  order  to  make  the  reaction  of  the 
mixture  distinctly  alkaline.  Sternberg  recommends  that  freshly  pre- 
pared milk  of  lime  should  contain  about  one  part  by  weight  of  hydrate 
of  lime  to  eight  parts  of  water.  This  should  be  used  freshly  prepared 
and  added  in  quantity  equal  in  amount  to  the  material  to  be  disinfected. 
The  mixture  should  be  allowed  to  stand  at  least  two  hours  before  final 
disposal.  Fortunately,  this  valuable  disinfecting  agent  is  very  cheap, 
so  that  it  can  be  used  with  a  liberal  hand  in  excess  of  the  amount  which 
scientific  tests  find  necessary,     (See  page  1171.) 

Lime  has  been  used  in  very  early  times  in  connection  with  the  dis- 
posal of  the  dead.  The  method  is  an  admirable  one  for  the  burial  and 
disinfection  of  bodies  dead  from  a  communicable  disease.  The  body 
should  be  placed  in  a  tight  coffin  with  twice  its  weight  of  fresh,  unslaked 
lime,  without  the  addition  of  water  or  moisture  in  any  form. 

Chlorinated  Lime  ("Chlorid  of  Lime"). — Chlorinated  lime  was 
used  as  a  disinfectant  and  deodorant  long  before  bacteriology  was  a 
science.  The  early  work  of  Sternberg  demonstrated  that  the  confidence 
placed  in  this  substance  from  an  empiric  standpoint  is  justified  by  scien- 
tific tests.  Chlorinated  lime  under  certain  circumstances,  in  fact,  is 
one  of  the  most  powerful  germicides  we  possess,  and  has  been  used  par- 
ticularly for  the  disinfection  of  sewage  and  water.     (See  page  900.) 

Chlorinated  lime,  popularly  miscalled  chlorid  of  lime,  is  a  soft, 
white,  friable  substance,  and  is  known  also  as  bleaching  powder.  It 
has  a  peculiar  chemical  composition  and  is  somewhat  unstable.  It  is 
made  by  passing  chlorin  gas  through  lime.  Owing  to  its  affinity  for 
moisture,  which  it  slowly  absorbs  from  the  air,  it  soon  becomes  pasty 
and  loses  some  of  its  chlorin ;  the  hypochlorites  are  reduced  to  chlorids, 
which  are  inert  as  germicides.  Freshly  prepared  chlorinated  lime 
should  have  a  very  slight  odor  of  free  chlorin,  A  strong  odor  of  this 
gas  indicates  that  deterioration  of  the  substance  is  taking  place.  It 
should  therefore  only  be  used  when  freshly  prepared  and  when  kept  in 
air-tight  receptacles. 

Chlorinated  lime  is  made  by  passing  nascent  chlorin  gas  over  very 
slightly  moist  calcium  hydroxid.  Concerning  its  exact  chemical  com- 
position there  is  some  disagreement.     It  is  represented  by  the  formula 


1158  CHEMICAL  AGENTS  OF  mSINFECTION 

CaOCl^  or  ClCaOCl  or  Ca(C10)Cl.  According  to  the  U.  S.  Pharma- 
copoeia it  should  contain  not  less  than  35  per  cent,  of  available  chlorin. 
The  British  standard  is  33  per  cent,  and  the  German  25  per  cent.  Chlor- 
inated soda  has  almost  the  same  germicidal  value  as  chlorinated  lime. 
Chlorinated  soda  is  sold  only  in  solution,  and  is  prepared  by  mixing  a 
solution  of  chlorinated  lime  and  sodium  carbonate. 

Chlorinated  lime  is  only  partially  soluble  in  water  or  in  alcohol. 
A  solution  in  water  of  0.5  to  1  per  cent,  will  kill  most  bacteria  in  one 
to  five  minutes.  A  5  per  cent,  solution  usually  destroys  spores  within 
an  hour. 

While  the  solution  of  chlorinated  lime  has  an  indefinite  composition 
it  is  generally  admitted  to  contain  calcium  hypochlorite  (CaClCaClOa), 
which  is  its  active  disinfecting  principle.  It  also  contains  calcium 
chlorid  (CaCl)2,  which  has  a  great  affinity  for  water,  and  calcium  hy- 
drate (Ca(0II)2),  which  is  largely  insoluble.  The  calcium  hypochlorite, 
upon  which  the  efficiency  of  the  solution  largely  depends,  is  readily  brok- 
en up,  even  by  the  carbon  dioxid  found  in  the  air  and  water,  into  hyper- 
chlorous  acid,  and  this  acid  is  so  unstable  that  even  in  the  presence  of 
light  it  is  decomposed  into  hydrochloric  acid  and  free  chlorin,  both  of 
which  are  active  germicides.  When  bleaching  powder  is  added  to  water 
it  is  the  nascent  oxygen,  rather  than  the  chlorin,  that  is  the  disinfecting 
agent.  (See  page  901.)  The  solution  is  highly  alkaline  and  has  distinct 
bleaching  powers.  Its  action  as  a  deodorant  depends  not  only  upon  its 
destructive  influence  upon  organic  matter  and  its  germicidal  properties, 
but  also  upon  its  great  affinity  for  water,  thus  acting  as  a  disinfectant. 
It  also  has  the  power  of  combining  with  hydrogen  sulphid  and  the  vola- 
tile ammoniacal  compounds  of  decomposition  and  decay. 

Chlorinated  lime  not  only  bleaches  but  is  destructive  to  fabrics.  If 
the  solution  is  employed  for  the  disinfection  of  body  linen  and  washable 
clothing  these  articles  must,  after  a  not  too  long  immersion,  be  thor- 
oughly washed  in  plenty  of  f resl»  water. 

It  should  be  remembered  that  the  hypochlorites  are  decomposed  and 
practically  rendered  inert  by  organic  matter.  They  should  therefore  be 
used  largely  in  excess.  Thus  a  preparation  containing  10  per  cent,  of 
available  chlorin  has  the  high  carbolic  coefficient  of  21.0,  but  on  mixing 
an  equal  amount  of  this  preparation  with  urine  and  allowing  the  mixture 
to  stand  one  hour  the  coefficient  falls  to  0.8  per  cent.  (Klein). ^  Gruber 
points  out  that  the  efficiency  of  chlorinated  lime,  when  used  to  disinfect 
cattle  wagons,  is  greatly  increased  by  first  thoroughly  washing  away 
the  organic  matter. 

Chlorinated  lime  may  be  used  either  as  a  dry  powder  or  in  solution. 
As  a  dry  powder  it  is  very  generally  used  by  strewing  it  into  damp 

^Public  Health,  Oct.,  1906.  Confirmed  by  Rideal,  Sommerville,  Moore,  and 
others. 


LIME  1159 

corners  of  cellars,  privies,  and  similar  places,  where  it  acts  as  a  deodor- 
ant and  desiccant  and  retards  the  growth  of  mold.  The  dry  substance 
may  also  be  used  to  disinfect  excreta.  For  this  purpose  enough  of  the 
chlorinated  lime  must  be  added  and  well  incorporated  with  the  mass  and 
sufficient  water  added  to  make  a  4  or  5  per  cent,  solution. 

In  the  U.  S.  Army  a  4  per  cent,  strength  of  chlorinated  lime  in  solu- 
tion is  officially  prescribed  for  use  in  the  disinfection  of  the  excreta  of 
the  sick,  it  being  specifically  stated  that  the  chlorinated  lime  so  used 
shall  be  of  good  quality  and  not  have  undergone  decomposition.  A  solu- 
tion known  as  the  "American  standard,"  containing  6  ounces  of  the 
powder  to  the  gallon,  is  largely  used  for  the  disinfection  of  discharges 
and  for  the  scrubbing  of  floors  and  other  surfaces. 

In  recent  years  chlorinated  lime  or  chlorinated  soda  has  come  into 
special  prominence  on  account  of  its  use  for  the  disinfection  of  drinking 
water.  A  surprisingly  minute  amount  will  disinfect  a  large  volume  of 
water.  The  amount  required  depends  upon  the  quantity  of  organic  mat- 
ter contained  in  the  water.  A  reasonably  clean  water  may  be  rendered 
practically  sterile  by  the  addition  of  0.1  of  a  part  of  chlorinated  lime 
(estimated  as  available  chlorin)  to  1,000,000  parts  of  water.  For  waters 
containing  organic  matter  as  much  as  1  to  25  parts  per  1,000,000  may 
be  required.     (See  page  903.) 

A  convenient  method  for  using  chlorinated  lime  to  disinfect  drink- 
ing water  is  to  add  1  gram  of  chlorinated  lime  containing  approxi- 
mately 30  per  cent,  of  available  chlorin  to  1  liter  of  water.  This  should 
be  mixed  thoroughly  and  enough  of  the  mixture  added  to  the  water  in 
question  to  make  1  part  of  chlorinated  lime  to  200,000  parts  of  water, 
and  then  allowed  to  stand  at  least  20  minutes  after  having  been 
thoroughly  shaken.  The  water  may  then  be  regarded  as  safe,  so  far  as 
typhoid,  cholera,  and  similar  infections  are  concerned.  A  solution  may 
be  prepared  by  adding  half  a  teaspoonful  of  chlorinated  lime  to  a  pint 
of  water.  Use  a  teaspoonful  of  this  to  10  gallons;  36  drops  to  1  gallon; 
or  9  drops  to  1  quart.    Let  stand  at  least  15  minutes. 

Chlorinated  lime  may  also  be  used  to  advantage  to  disinfect  the 
bath  water  in  cases  of  typhoid  fever,  dysentery,  cholera,  or  other  com- 
municable diseases.  It  may  also  be  used  for  the  disinfection  of  springs, 
wells,  cisterns,  tanks,  ^and  many  other  purposes  (page  905), 

Javelle  water  consists  of  chlorinated  potash,  65  grams;  chlorinated 
lime,  90  grams;  water  sufficient  to  make  1,000  grams. 

Labarraque's  Solution. — Labarraque's  solution  is  an  aqueous  solu- 
tion of  several  chlorin  compounds,  chiefly  sodium  hypochlorite  (N"aC10) 
and  sodium  chlorid  (NaCl),  and  should  contain  at  least  2.6  per  cent,  by 
weight  of  available  chlorin  as  determined  by  titration  with  thiosulphate. 
The  solution  is  clear  and  colorless  when  pure.  If  prepared  with  an  excess 
of  chlorin  it  is  yellowish  in  color.     It  has  a  feeble  odor  of  chlorin  and 


1160  CHEMICAL  AGENTS  OF  DISINFECTION 

bleaches  indigo,  litmus,  and  vegetable  dyes.  In  practice  this  solution 
diluted  with  water  1  to  4  is  mainly  used  for  the  disinfection  of  the  per- 
son, and  in  surgery,  but  as  it  is  more  expensive  and  somewhat  less  effi- 
cient than  chlorinated  lime  it  has  no  advantages  over  that  substance. 

Antiformin. — Antiformin  is  the  patented  name  of  a  disinfectant 
which  was  introduced  in  1900  by  Victor  Tornell  and  Axel  Sjoo  of 
Stockholm  as  a  cleansing  material  for  fermenting  vats  in  breweries,  but 
it  is  only  since  the  investigations  of  Uhlenhuth  and  Xylander  ^  in  1908 
that  it  has  come  into  prominence  in  bacteriological  and  sanitary  work. 

Antiformin  consists  of  equal  parts  of  liquor  sodae  chlorinatae  of  the 
British  Pharmacopoeia  and  a  15  per  cent,  solution  of  caustic  soda.  The 
formula  for  the  liquor  sodae  chlorinatae  is  as  follows : 

Sodium  carbonate 600 

Clilorinated  Ume 400 

Distilled  water 4,000 

Dissolve  the  sodium  carbonate  in  1,000  c.  c.  of  the  distilled  water; 
triturate  thoroughly  the  chlorinated  lime  in  the  remainder  of  the  water ; 
filter ;  mix  the  two  and  filter  again. 

Antiformin  has  a  strong  germicidal  action  in  weak  solutions  (2  to 
5  per  cent.),  killing  ordinary  cocci  and  some  bacilli  rapidly,  five  minutes 
at  most  being  sufficient.  In  this  respect  antiformin  acts  more  rapidly 
and  surely  than  either  of  its  component  parts  used  alone.  It  has,  how- 
ever, very  slight  action  upon  the  tubercle  bacillus,  the  smegma  bacillus, 
"  and  other  organisms  belonging  to  the  acid-fast  group. 

Antiformin  is  an  almost  colorless  liquid,  with  a  strong  odor  of 
chlorin,  and  is  strongly  alkaline.  It  keeps  fairly  well  without  particular 
precautions  being  taken.  It  has  deep  powers  of  penetration,  owing  to 
its  ability  to  dissolve  and  render  homogeneous  the  various  substances  in 
which  bacteria  are  often  found,  such  as  sputum,  feces,  pus,  urinary  sedi- 
ment^ and  even  small  pieces  of  tissue. 

The  germicidal  action  of  antiformin  is  doubtless  due  to  the  energetic 
oxidizing  properties  of  the  chlorinated  lime.  The  fact  that  it  does  not 
kill  the  tubercle  bacillus  and  other  acid-fast  organisms  seems  to  be  due 
to  the  biochemical  nature  of  these  bacilli.  The  fatty  or  waxy  capsule 
which  is  present  and  which  gives  them  their  acid-fast  property  acts  as 
an  impervious  coat,  resisting  the  dissolving  action  of  the  antiformin, 
and  so  protects  the  protoplasm  of  the  bacilli  from  its  germicidal  action. 
The  tubercle  bacillus  may  be  isolated  in  pure  culture  by  exposing 
tuberculous  sputum  to  a  20  per  cent,  solution  of  antiformin  for  24  hours 
at  room  temperature  or  4  to  6  hours  at  incubator  temperature.  The 
bacilli  may  then  be  thrown  down  by  centrifugalization,  washed  free  of 
alkali,  and  then  planted  upon  solidified  egg  or  other  suitable  culture 
medium,  or  injected  into  susceptible  animals. 

^B.  klin,  Wochenschr.,  LXV,  No.  29,  July  20,  1908, 


ACIDS  1161 

While  antiformin  is  therefore  a  very  active  germicide  for  the  ordi- 
nary bacteria  it  cannot  be  depended  upon  for  the  acid-fast  group. ^ 

Bromin  and  lodin. — Bromin  and  iodin  are  very  potent  germicides- 
Tliey  have  about  the  same  value  as  chlorin,  both  in  their  gaseous  state 
and  in  solution.  The  tincture  of  iodin  is  now  much  used  in  surgery  for 
the  disinfection  of  the  skin. 

Ferrous  Sulphate. — Ferrous  sulphate  has  long  been  valued  as  a  disin- 
fectant on  account  of  its  property  as  a  deodorant,  and  has  been  used  ex- 
tensively, being  a  comparatively  cheap  substance.  Its  germicidal  power 
has  been  shown  by  laboratory  tests  to  be  rather  feeble,  so  that  it  cannot 
be  depended  upon  as  a  trustAvorthy  disinfectant. 

Ferrous  sulphate  (FeS04),  commonly  called  green  vitriol,  iron  vit- 
riol, or  copperas,  consists  of  large  bluish-green  crystals  which  slowly 
effervesce  and  oxidize  in  the  air.  It  is  soluble  in  about  twice  its  weight 
of  cold  water,  forming  a  greenish  solution.  It  is  a  much  less  powerful 
germicide  than  the  sulphate  of  copper,  and  is  limited  in  use  to  the  de- 
struction of  odors,  and  even  for  this  purpose  is  not  always  successful. 
It  is  still  used  with  lime  for  the  clarification  of  turbid  waters. 

Sulphate  of  Copper. — Sulphate  of  copper  (CuSO^)  is  about  half  as 
strong  as  bichlorid  of  mercury.  It  has  a  peculiar  selective  action  in  that 
it  has  a  remarkable  affinity  for  many  species  of  algae  which  are  killed 
in  the  proportion  of  1  to  1,000,000.  Algae  are  the  most  common  cause 
of  unpleasant  odors  and  tastes  in  drinking  water,  and  sulphate  of  cop- 
per may  therefore  be  used  to  check  or  destroy  their  growth.  (See 
page  909.)  In  these  great  dilutions  sulphate  of  copper  will  not  kill 
the  typhoid  bacillus,  so  that  it  is  not  practical  to  use  it  as  a  disinfectant 
in  water. 

Chlorid  of  Zinc. — Chlorid  of  zinc  (ZnCla)  was  at  one  time  highly 
valued  as  a  disinfectant,  and  is  still  extensively  used  despite  the  fact 
that  it  stands  rather  low  in  the  list  of  germicidal  agents.  It  has  even 
weaker  power  as  a  disinfectant  than  ferrous  sulphate  and  cannot  be 
recommended  as  trustworthy.    It  has  some  value  as  a  deodorant. 


ACIDS 

Acids  in  sufficient  concentration  are  very  effective  germicides.  An 
amount  of  acid  which  equals  40  c.  c.  of  normal  hydrochloric  acid  per 
liter  is  sufficient  to  prevent  the  growth  of  all  kinds  of  bacteria  and  to 
kill  many.  The  variety  of  acid  makes  little  difference.  The  mineral 
acids  are  more  corrosive  and  also  more  germicidal  than  the  vegetable 

^  Paterson,  R.  C. :  "A  Report  on  the  Use  of  'Antiformin'  for  the  Detection 
of  Tubercle  Bacilli  in  Sputum,  etc.,"  Jour,  of  Med.  Research,  Vol.  XXII,  No.  2, 
April,   IfllO,  p.  315. 


1163  CHEMICAL  AGENTS  OF  DISINFECTION 

acids.  A  1  to  500  solution  of  sulphuric  acid  kills  typhoid  hacilli  within 
one  hour.  Hydrochloric  acid  is  about  one-third  weaker,  and  acetic  acid 
somewhat  weaker  still.  Citric,  tartaric,  malic,  formic,  and  salicylic  acids 
are  about  equal  to  acetic  acid.  Boric  acid  destroys  the  less  resistant 
bacteria  in  2  per  cent,  solution  and  inhibits  the  others.     (Park.) 


ALCOHOL 

Alcohol  has  both  antiseptic  and  germicidal  properties.  In  solutions 
of  1-1,000  the  growth  of  some  bacteria  is  somewhat  delayed.  Many 
microorganisms  grow  abundantly  in  40  per  cent,  alcohol  and  some  in 
stronger  solutions.  Dry  bacteria  may  be  exposed  to  absolute  alcohol  for 
24  hours  without  losing  their  vitality,  while  60  to  70  per  cent,  alcohol 
has  definite  germicidal  power  to  both  dry  and  moist  microorganisms. 
The  explanation  of  this  curious  phenomenon  seems  to  be  that  alcohol 
fails  to  penetrate  the  microbe  unless  in  the  presence  of  water.  Under 
40  per  cent  the  germicidal  action  is  very  slow  so  that  the  limits  of  alcohol 
as  a  disinfectant  may  be  placed  between  50  and  70  per  cent.  In  this 
strength  it  is  equivalent  to  about  3  per  cent,  carbolic  acid  provided  there 
is  little  or  no  albuminous  matter  present.  Alcohol  precipitates  protein 
which  therefore  seriously  interferes  with  its  germicidal  property.  Many 
germicidal  substances  which  are  potent  when  dissolved  in  water,  have 
comparatively  little  effect  when  dissolved  in  alcohol.  . 


SOAPS 

Ordinary  soaps  have  but  limited  disinfecting  power.  According  to 
Behring  the  germicidal  power  of  soaps  depends  upon  their  alkalinity, 
but  Serafini  more  correctly  points  out  that  the  free  alkali  present,  even 
in  concentrated  soap  solutions,  is  so  small  in  amount  that  it  can  exert 
no  disinfecting  action  whatever,  and  that  neither  the  alkali  nor  the 
fatty  acid,  nor  the  combination  of  the  two  is  the  efi^ective  agent. 

Unfortunately,  the  disinfecting  power  of  soap  solutions  is  not 
marked  enough  to  make  them  trustworthy  disinfectants  despite  their 
great  value  as  detergents.  The  common  commercial  soaps,  especially 
the  colored  soaps,  are  frequently  of  very  poor  quality,  containing  rosin 
instead  of  fat,  and  are  not  to  be  depended  upon.  The  soft  soaps  should 
also  be  avoided  on  account  of  the  presence  of  all  the  impurities  of  the  fat 
and  alkali  from  which  they  are  made.  There  are  other  conditions  which 
render  the  use  of  soaps  uncertain,  the  chief  of  which  is  the  hardness 
of  the  water. 

The  action  of  soap  solutions  is  much  influenced  by  the  temperature, 


SOAPS 


1163 


which  is  easy  to  understand  when  we  recall  the  powerful  germicidal 
action  of  hot  water  alone.  It  has  been  shown  that  soap,  even  in  strong 
solution  and  with  prolonged  exposure,  cannot  be  trusted  to  destroy  the 
infection  of  typhoid,  cholera,  or  the  micrococci  of  suppuration.  There- 
fore soaps  alone  cannot  be  depended  upon  for  the  disinfection  of  objects 
and  clothing,  but  in  conjunction  with  certain  compatible  chemicals,  and 
also  with  the  mechanical  cleansing  which  always  accompanies  their  ap- 
plication, soaps  have  a  wide  and  varied  usefulness. 

Soap  solutions  should  always  be  made  with  soft  water.  The  addi- 
tion of  one  of  the  caustic  alkalis,  as  lye,  increases  their  germicidal  and 
detergent  value.  The  solution  should  be  strong,  containing  not  less 
than  10  per  cent,  of  soap,  and  the  water  should  be  as  hot  as  possible  and 
applied  with  mops  or  brushes. 

Medicated  soaps  are  for  the  most  part  a  snare  and  delusion  so  far 
as  any  increased  germicidal  action  is  concerned.  In  fact,  the  addition 
of  carbolic  acid,  bichlorid  of  mercury,  and  other  substances  which  have 
the  property  of  combining  chemically  with  the  soap  seems  actually  to 
diminish  the  disinfecting  value  of  the  substance.  As  a  rule  a  very  small 
quantity  of  the  disinfecting  substance  is  added  to  the  soap,  and  when  we 
call  to  mind  what  an  exceedingly  small  quantity  of  soap  is  generally 
used  for  the  ordinary  washing  of  the  skin  and  the  further  dilution  of 
this  small  amount  by  the  water  used  it  is  easy  to  understand  that  medi- 
cated soaps  as  ordinarily  applied  cannot  have  an  energetic  disinfecting 
action. 

An  exception  seems  to  be  the  soap  devised  by  McClintock,  in  which 
a  mercury  salt  exists  unchanged  and  active.  He  found  that  double 
iodid  of  mercury  answers  this  purpose  in  the  proportion  of  0.05  to  2 
per  cent.  A  solution  containing  1  per  cent,  of  the  soap  was  found 
by  him  to  be  fatal  to  pus  cocci,  cholera,  diphtheria,  and.  typhoid  bacilli 
in  one  minute.  This  soap  does  not  attack  nickel,  silver,  aluminium,  steel 
instruments,  or  lead  pipes,  and  does  not  coagulate  albumin. 

The  following  is  a  table  of  comparative  antiseptic  values  taken  from 
Park : 

Tables  of  Antiseptic  Values 


Alum 

Aluminium  acetate .  . 
Ammonium  chlorid .  . 

Boric  acid 

Calcium  chlorid 

Calcium  hypochlorite 

Carbolic  acid 

Chloral  hydrate 

Cupric  sulphate 

Ferrous  sulphate .... 
Formaldehyd  (40%) . 
Hydrogen  peroxid  .  .  . 


222 

6,000 

9 

143 

25 

1,000 

333 

107 

2,000 

200 

10,000 

20,000 

Mercuric  chlorid 

Mercuric  iodid 

Potassium  bromid 

Potassium  iodid 

Potassium  permanganate .  . 

Pure  formaldehyd 

Quinin  sulphate 

Silver  nitrate 

Sodium  borate 

Sodium  chlorid 

Zinc  chlorid 

Zinc  sulphate 


14,300 

40,000 
10 

10 

300 

25,000 
800 

12,500 
14 

6 

500 

20 

1164  CHEMICAL  AGENTS  OF  DISINFECTION 

CONVENIENT  FORMULAE  FOR  DISINFECTING  SOLUTIONS 

Bichlorid  of  Mercury — Corrosive  Sublimate. 

Bichlorid  of  mercury 1  dram     |   1  gram 

Water   1  gallon   |   1  liter 

Mix  and  dissolve.  Label  "Poison!"  This  is  approximately  a  1  to 
1,000  solution.  One  ounce  of  this  solution  contains  very  nearly  half  a 
grain  of  corrosive  sublimate.  Useful  for  disinfecting  clothing,  the 
hands,  the  surfaces  of  walls,  floors,  furniture,  etc.  Not  serviceable  for 
feces  or  material  containing  much  organic  matter. 

Formalin. 

Formalin    13  ounces   |   100  c.  c. 

Water   1  gallon    |       1  liter 

Formalin  is  a  watery  solution  containing  40  per  cent,  formaldehyd. 
The  above  solution  contains  approximately  10  per  cent,  of  formalin  and 
is  useful  for  the  disinfection  of  clothing  and  a  great  variety  of  objects. 
As  it  has  no  corrosive  action  it  does  not  bleach  pigments  or  rot  fabrics. 
When  used  to  disinfect  feces  twice  the  above  strength  should  be  used. 

Milk  of  Lime. — Slake  a  quart  of  freshly  burnt  lime,  in  small  pieces, 
with  three-fourths  of  a  quart  of  water,  or,  more  exactly,  50  parts  of 
water  by  weight  with  100  parts  of  lime.  A  dry  powder  of  slaked  lime 
(calcium  hydroxid)  results.  Prepare  the  milk  of  lime  shortly  before 
it  is  to  be  used  by  mixing  1  quart  of  this  dry  calcium  hydroxid  with  4 
quart  of  water.  Air-slaked  lime  is  worthless.  Slaked  lime  may  be 
preserved  some  time  if  inclosed  in  an  air-tight  container.  Milk  of  lime 
is  especially  useful  for  the  disinfection  of  feces ;  an  equal  quantity  should 
be  added  to  the  mass  and  thoroughly  mixed. 

Carbolic  Acid. 

Crude  carbolic  acid   (or  phenol)...      7  ounces   |   50  c.  c. 
Water  1  gallon    |     1  liter 

The  solution  is  facilitated  by  dissolving  in  hot  water.  This  makes 
approximately  a  5  per  cent,  solution.  The  addition  of  from  12  to  14 
ounces  of  common  salt  to  each  gallon  increases  its  germicidal  power, 
especially  when  used  for  the  disinfection  of  excreta.  The  crude  carbolic 
acid  is  more  powerful  than  pure  phenol,  but  can  only  be  used  for  rough 
work,  such  as  floors,  feces,  sputum,  etc.  For  the  disinfection  of  cloth- 
ing phenol  should  be  used  and  the  solution  may  be  mixed  half  and  half 
with  water,  making  approximately  a  21/0  per  cent,  solution. 


SOAPS  1165 

Chlorinated  Lime  ("Chlorid  of  Lime"). 

Chlorinated  lime    '. 3  ounces    \    30  grams 

Water   1  gallon    |      1  liter 

Mix.  This  is  about  a  3  per  cent,  solution.  It  is  exceedingly  power- 
ful and  is  useful  for  the  disinfection  of  excreta,  privy  vaults,  cesspools, 
and  many  other  purposes.  It  is  an  active  bleaching  agent  and  destroys 
fabrics  in  this  concentration. 


CHAPTEE  IV 
METHODS   OF  DISINFECTION 

A  few  instances  are  given  upon  the  following-  pages  of  the  best  meth- 
ods of  disinfecting  rooms,  excreta,  and  fomites.  The  examples  selected 
have  been  taken  as  types  of  a  class.  In  public  health  work  the  things 
most  frequently  needing  disinfection  are  feces,  sputum,  and  other  dis- 
charges from  the  body;  bed  and  body  linen,  and  other  fabrics;  and  bed- 
rooms. The  disinfection  of  water  and  the  pasteurization  of  milk  have 
already  been  considered.  The  disinfection  of  ships  is  described  under 
Quarantine. 

Air. — It  is  quite  impossible  to  disinfect  the  air  of  a  room  during  its 
occupancy.  In  fact,  ordinarily  little  heed  need  be  given  to  the  air  itself. 
Any  of  the  known  volatile  substances  in  sufficient  concentration  to  kill 
microorganisms  would  render  the  air  unendurable.  It  is  absurd  to  place 
such  substances  as  carbolic  acid,  formalin,  or  chlorinated  lime  in  an 
open  pan  in  the  sickroom  or  in  the  bathroom  with  the  idea  that  they  are 
serving  a  useful  purpose  in  disinfecting  the  atmosphere  or  in  preventing 
the  spread  of  infection.  Occasionally  a  deodorant,  such  as  formalin, 
may  be  used  with  advantage  about  the  room,  but  where  proper  cleanli- 
ness and  ventilation  are  observed  such  substances  are  rarely  called  for. 

It  is  of  first  importance  to  prevent  the  infection  of  the  air  of  the 
room  by  taking  precautions  applicable  to  the  particular  infection  in 
question.  Thorough  ventilation  should  be  maintained,  and  in  this  way 
any  chance  infection  is  soon  lost  by  dilution  or  killed  by  the  sun.  An 
open  fireplace  is  admirable  for  the  ventilation  and  purification  of  the 
air  of  sickrooms,  for  by  this  method  the  infection  is  not  only  carried 
away,  but  is  destroyed  by  the  heat  of  the  fire  in  exit.  The  hanging  of 
sheets  wet  with  bichlorid  of  mercury  or  some  other  germicidal  solution 
at  the  doorway  serves  no  useful  purpose  except  as  a  reminder  to  those 
passing  in  and  out. 

When  a  room  has  become  badly  infected,  say  from  a  case  of  pul- 
monary tuberculosis,  and  there  is  danger  of  infection  through  the  dust, 
it  should  be  given  a  preliminary  fumigation  with  formaldehyd,  which 
will  partly  protect  the  operators  who  have  to  take  up  the  carpets  or  re- 
move the  bedding  and  other  articles  to  the  steam  sterilizer. 

Rooms. — The  disinfection  of  a  living-room  calls  for  all  the  resources 
of  the  disinfector's  art.  The  fact  that  it  is  necessary  to  bring  the  appa- 
ratus and  materials  to  the  room  in  order  to  disinfect  it  and  its  contents 

1166 


METHODS  OF  DISINFECTION  1167 

is  one  of  the  main  difficulties  aud  will  often  require  the  ingenuity  and 
always  the  vigilance  of  the  operator. 

The  method  to  be  employed  for  the  disinfection  of  a  room  will  vary 
somewhat  with  the  infection  for  which  the  disinfection  is  done.  In 
routine  work  in  the  treatment  of  rooms  liable  to  be  infected  with  a 
variety  of  bacterial  viruses  formaldehyd  gas  is  the  most  generally  useful 
agent  we  possess.  In  the  case  of  yellow  fever  or  malaria  insecticides  must 
be  selected;  in  the  case  of  plague  our  efforts  must  be  directed  against 
rats,  mice,  fleas,  as  well  as  the  destruction  of  the  plague  bacillus.  In 
cholera  and  typhoid  fever  we  must  pay  particular  attention  to  the  feces, 
urine  and  the  objects  soiled  by  them,  etc. 

Certain  articles  commonly  found  in  living-rooms,  such  as  bedding, 
carpets,  rugs,  cuspidors,  upholstered  furniture,  and  other  objects  liable 
to  become  deeply  infected  must  be  treated  separately  by  some  process 
applicable  to  each  article.  None  of  the  gaseous  disinfectants  can  be 
trusted  to  penetrate  enough  to  render  articles  of  this  class  safe.  In 
case  the  room  is  so  constructed  that  it  is  impracticable  to  disinfect  it 
with  a  gas  the  walls,  floors,  and  all  the  contents  of  the  room  must  be 
disinfected  separately  in  accordance  with  suitable  methods  for  each  case. 

Ordinarily  carpets  and  rugs  should  be  left  in  place  until  a  pre- 
liminary gaseous  disinfection  is  accomplished.  They  may  then  be  taken 
up  and  removed  for  steam  sterilization,  after  which  they  should  be  gone 
over  with  a  vacuum  cleaner  and  finally  hung  in  the  sun  for  a  day  or  two. 
If  carpets,  rugs,  upholstered  furniture,  mattresses,  pillows,  quilts,  or 
other  articles  have  become  badly  contaminated  with  infected  discharges 
the  soiled  areas  should  be  thoroughly  saturated  with  a  strong  solution  of 
formalin.  Bedding,  towels,  curtains,  clothing,  and  other  articles  of  like 
nature  may  be  left  in  the  room  exposed  to  the  action  of  the  gas,  but 
should  afterwards  be  removed  for  boiling,  steaming,  or  immersion  in 
one  of  the  germicidal  solutions,  as  none  of  the  gases  can  be  relied  upon 
for  the  disinfection  of  fabrics.  Articles  removed  from  the  room  for  dis- 
infection should  be  placed  in  a  bag  or  wrapped  in  a  sheet  wet  Avith 
bichlorid  of  mercury.  Eubbish  that  has  collected  in  the  room  should 
be  gathered  and  burned.  The  cuspidors  and  their  contents  require  spe- 
cial treatment.  Door  knobs,  bed  rails  and  other  surfaces  handled  by  the 
patient  or  soiled  with  discharges  should  be  wiped  with  bichlorid  or  car- 
bolic solution. 

The  gaseous  disinfectants  cannot  be  depended  upon  where  penetra- 
tion is  required;  therefore  any  article  believed  to  be  deeply  or  badly 
infected  should  be  treated  with  another  method. 

After  the  room  has  been  properly  prepared  and  all  has  been  made 
tight,  it  is  filled  with  the  gas  according  to  the  method  selected.  The 
room  should  then  be  sealed  in  such  a  way  that  it  cannot  be  broken  with- 
out the  knowledge  of  the  disinfector.    After  the  proper  time  has  elapsed 


1168  METHODS  OF  DISINFECTION 

the  room  should  be  opened  by  the  disinfector  himself  and  the  operation 
should  not  be  considered  successful  unless  there  is  a  distinct  odor  of 
the  gas  present.  Windows  and"  doors  may  then  be  opened  so  as  to  allow 
the  gas  to  blow  away.  Cultures  of  a  test  organism  should  always  be 
exposed  in  order  to  control  the  efficiency  of  the  fumigation  in  each 
case. 

A  room  which  has  been  carefully  treated  as  above  outlined  may  be 
considered  disinfected,  but  it  is  always  advisable  to  follow  the  disinfect- 
ing processes  with  a  very  thorough  mechanical  cleansing  and  a  good 
sunning  and  airing. 

When  a  room  is  to  be  purified  without  the  use  of  one  of  the  gaseous 
disinfectants  a  somewhat  different  procedure  is  followed.  Article  after 
article  is  removed  piecemeal  and  disinfected  by  an  appropriate  method. 
After  the  room  is  emptied  the  walls  and  their  surfaces  are  flushed, 
scrubbed,  or  mopped  with  bichlorid  of  mercury,  1  to  1,000,  or  one  of 
the  alkaline  cresols. 

Stables. — The  disinfection  of  a  stable  requires  a  particularly  thorough 
application  of  all  the  resources  at  the  hand  of  the  disinfector.  The 
conditions  met  with  in  a  stable  render  its  disinfection  doubly  hard,  not 
only  on  account  of  the  accumulation  of  organic  filth  which  has  worked 
into  the  many  crevices  and  saturated  the  woodwork,  but  on  account  of 
the  high  resistance  of  anthrax  and  tetanus  spores,  for  which  stables  are 
sometimes  disinfected.  In  addition  to  these  diseases  stables  require 
disinfection  on  account  of  tuberculosis,  glanders,  pleuropneumonia,  and 
various  diseases  of  man  as  well  as  those  of  the  domestic  animals. 

It  is  advisable  to  give  the  stable  a  preliminary  fumigation,  preferably 
with  sulphur,  in  order  to  destroy  surface  infection  and  the  vermin  which 
always  infest  these  places.  The  preliminary  disinfection  is  especially 
important  in  the  case  of  plague  and  glanders,  not  only  to  prevent  the 
spread  of  the  infection,  but  as  a  safeguard  for  the  disinfectors.  Then 
remove  all  small  articles  that  need  disinfection.  The  blankets  should 
be  wrapped  in  moist  bichlorid  sheets  and  boiled,  steamed,  or  immersed 
in  a  strong  germicidal  solution.  Buckets,  currycombs,  brushes,  stall  tools, 
and  other  equipments  that  have  been  in  contact  with  the  sick  animals  or 
with  infectious  materials  should  be  mechanically  cleaned  with  a  hot 
carbolic  solution  in  which  they  may  be  allowed  to  soak  over  night.  Me- 
tallic and  Avooden  objects  or  utensils  should  be  given  a  thorough  prelim- 
inary cleansing  with  a  stiff  brush  and  hot  Avater  and  soap,  and  then 
boiled  or  immersed  in  a  5  per  cent,  solution  of  carbolic  acid  or  2  per 
cent,  solution  of  cresol  for  several  hours.  Leather  articles,  as  harness 
or  equipment,  should  receive  a  similar  preliminary  cleansing  and  be 
scrubbed  with  either  a  strong  solution  of  bichlorid  of  mercury  or  car- 
bolic acid. 

All  hay  and  grain  should  be  removed  from  the  racks  and  mangers 


METHODS  OF  DISINFECTION  1169 

and  all  bedding  from  the  floors.  After  its  careful  collection  at  some 
designated  point  this  refuse  should  be  saturated  with  petroleum  and 
destroyed  by  fire. 

The  stable  must  now  be  soaked  with  a  strong  antiseptic  solution  ap- 
plied with  a  hose  or  splashed  on  all  surfaces  by  means  of  mops.  The 
floors,  corners,  and  stalls  must  be  saturated  with  the  solution.  On 
account  of  the  presence  of  so  much  albuminous  matter  carbolic  acid  or 
one  of  its  derivatives  is  preferred  for  this  purpose  to  chlorinated  lime  or 
sublimate  solutions.  Now  scrape  out  the  debris  from  all  the  cracks  in 
the  floors  and  walls;  collect  it  for  burning.  Then  clean  the  woodwork 
with  hot  lye  or  a  strong  alkaline  soap  solution  and  follow  with  another 
general  hosing  with  the  antiseptic  liquid. 

After  several  days'  exposure  to  air  and  sunshine  the  interior  of  the 
stable  should  receive  a  fresh  coat  of  whitewash,  applied  quickly,  and 
prepared  from  freshly  burnt  lime. 

The  watering  troughs  are  very  apt  to  be  infected,  especially  in  deal- 
ing with  glanders.  In  all  instances  not  only  the  troughs  and  watering 
buckets  should  be  disinfected  with  the  water  remaining  in  them,  for 
often  there  is  no  drain  or  sewer,  and  this  water  poured  on  the  ground 
may  be  a  source  of  subsequent  infection.  The  water  may  first  be  disin- 
fected by  the  addition  of  a  suitable  amount  of  chlorinated  lime  or  any 
of  the  standard  germicides.  The  troughs  are  then  to  be  mechanically 
cleaned,  thoroughly  removing  all  organic  matter,  and  then  applying  a 
strong  germicidal  solution  to  both  the  inside  and  outside.  For  metal- 
lined  troughs  the  use  of  bichlorid  of  mercury  is,  of  course,  inapplicable, 
and  for  such  carbolic  acid,  alkaline  creosotes  or  formalin  is  recommended. 
Most  germicides  are  poisonous,  and  must  therefore  be  finally  washed 
out  of  the  trough  or  buckets  by  flushing  with  fresh  water  and  then  air- 
ing in  the  sunlight  before  they  are  again  used.  A  strong  carbolic, 
formalin,  or  chlorinated  lime  solution  should  be  poured  down  all  pipes 
and  drains. 

Sometimes  the  ground  in  the  immediate  vicinity  of  the  stable  will 
need  attention.  Lime  or  the  gasoline  torch  will  generally  be  found  most 
useful  for  this  purpose.  Carcasses  and  excreta  are  to  be  disinfected  and 
disposed  of  according  to  the  methods  given  under  these  titles. 

Railroad  Cars. — Eailroad  cars  are  rooms  on  wheels.  The  principles 
of  their  disinfection  present  nothing  novel,  but  the  application  presents 
practical  difficulties. 

Flat  cars  or  open  cars  seldom  need  disinfection,  for,  even  should 
they  become  infected,  the  exposure  to  the  sun  and  weather  is  sufficient  to 
render  them  safe  from  the  danger  of  conveying  disease.  They  may 
readily  be*  disinfected  whenever  that  may  be  necessary  by  scrubbing  or 
flushing  them  with  carbolic  acid  or  bichlorid  of  mercury  solutions. 
.    Freight  cars  or  box  cars  seldom  need  disinfection.    They  sometimes 


1170  METHODS  OF  DISINFECTION 

require  fumigation  on  ac(:;ount  of  mosquitoes,  fleas,  or  rats  and  mice, 
which  such  cars  may  carry.  Freight  cars  are  best  treated  for  this  pur- 
pose with  sulphur  dioxid.  In  actual  practice  it  will  sometimes  be  found 
useful  to  steam  them  with  steam  from  the  locomotive. 

Cattle  cars  and  cars  used  to  transport  live  stock  need  special  atten- 
tion, particularly  if  anthrax,  tetanus,  glanders,  foot-and-mouth  disease, 
or  tuberculosis  is  the  infection  with  which  they  are  contaminated.  The 
disinfection  of  cars  of  this  type  is  so  much  like  the  disinfection  of  a 
stable  that  it  is  unnecessary  to  repeat  the  description  here.  Cars  of  this 
type,  as  well  as  all  cars,  should  be  kept  scrupulously  and  constantly  clean. 

Day  Coaches  and  Parlor  Cars. — If  the  disinfection  is  done  as  a 
precautionary  measure  it  is  sufficient  to  fill  the  coach  with  formaldehyd 
gas,  which  should  be  followed  by  a  thorough  mechanical  cleansing. 
The  carpets  and  rugs  and  all  similar  articles,  including  the  upholstered 
seats  and  backrests,  if  removable,  should  be  taken  from  the  car  for 
vacuum  treatment  and  then  exposed  several  hours  to  the  sunshine.  The 
floors  should  be  mopped  or  scrubbed  with  one  of  the  germicidal  solutions 
and  the  spittoons  should  be  well  rinsed  in  a  warm  carbolic  bath  and  the 
contents  disposed  of  in  one  of  the  ways  mentioned  under  the  heading 
Sputum. 

If  the  disinfection  is  done  on  account  of  known  contamination  with 
one  of  the  communicable  diseases  the  car  is  treated  exactly  as  a  room 
would  be  under  like  conditions. 

A  railroad  coach  is  likely  to  harbor  mosquitoes,  flies,  and  other 
insect  pests  that  may  carry  disease;  therefore  precautions  will  have  to 
be  taken  to  keep  these  insects  out  of  cars  leaving  districts  infected  with 
yellow  fever,  typhus  fever,  malaria,  plague,  etc.,  or  measures  will  have 
to  be  taken  to  destroy  them  after  they  get  on  board.  As  both  these 
requirements  are  difficult,  if  not  impracticable,  it  will  usually  be  found 
best  to  provide  relays  at  a  convenient  point  and  require  the  passengers 
to  change  cars  upon  leaving  an  infected  for  an  infectible  area. 

Sleeping  cars  present  a  greater  difficulty  than  any  other  rolling 
stock.  The  berths  are  apt  to  become  infected  and  the  infective  agent  may 
live  there  a  very  long  time,  especially  as  they  are  kept  closed — almost 
hermetically  sealed,  against  fresh  air  and  sunshine  during  the  daytime. 
Much  of  the  difficulty  encountered  in  the  disinfection  of  the  sleeping  car 
is  due  to  peculiarities  in  construction,  such  as  the  compact  manner  in 
which  the  bedding  is  stowed  away,  the  heavy  and  unnecessary  carpets 
and  hangings,  the  excessive  molding  and  ornamentation  of  the  older  type 
of  cars,  the  use  of  such  materials  as  plush  for  upholstering,  etc.  The 
wash  basins  and  other  objects  in  the  toilet-rooms  are  liable  to  contamina- 
tion with  infected  discharges  from  the  mouth  and  nose.  The  faucets 
should  be  so  arranged  as  to  permit  washing  with  running  water,  thus 
eliminating  danger  from  the  bowl. 


METHODS  OF  DISINFECTION  1171 

Before  attempting  to  fumigate  the  interior  of  a  sleeping  car  or  a 
passenger  coach  with  one  of  the  disinfectants  it  is  important  to  close  the 
sashes  and  all  the  ventilator  openings  for  the  Pintsch  gas  flames.  Much 
gas  will  be  lost  through  the  open  hopper  of  the  water-closet  unless  that  is 
tamponed.  Some  cars  have  a  system  of  ventilating  duces  of  fresh  air 
entering  under  the  seat  or  somewhere  near  the  bottom  of  the  car.  This 
must  be  closed.  Formaldehyd  gas  and  hydrocyanic  acid  gas  are  practi- 
cally the  only  gases  which  may  be  used  for  the  treatment  of  the  sleeping 
car.  As  these  gases  lack  the  power  of  penetration,  all  the  berths  must  be 
opened  and  all  the  bedding  and  other  fabric  should  be  removed  for 
steaming  or  other  treatment.  Hydrocyanic  acid  is  especially  serviceable 
for  the  destruction  of  bedbugs  and  vermin  which  frequently  infest  sleep- 
ing cars. 

After  the  bedding,  hangings,  carpets,  and  other  fabrics  have  been 
removed  from  the  car  the  toilet-room  should  be  given  special  attention. 
The  drinking  glasses,  the  wash  basins  and  slabs  of  the  washstands,  the 
brushes  and  combs,  the  seat  of  the  water-closet,  and  other  objects  liable 
to  infection  should  be  washed  or  immersed  in  one  of  the  standard  germi- 
cidal solutions. 

Feces. — The  disinfection  of  feces  is  most  important  because  these  dis- 
charges are  most  dangerous  and  at  the  same  time  most  difficult  to 
render  safe.  Fecal  discharges  may  be  disinfected  with  carbolic  acid, 
cresols,  lime,  chlorinated  lime,  or  formalin,  as  described  below.  In  hos- 
pitals the  infected  discharges  are  sometimes  boiled  or  charged  with 
steam  in  an  appropriate  apparatus  with  the  addition  of  a  deodorizing 
substance,  as  potassium  permanganate. 

From  patients  the  discharges  should  be  received  in  a  glass  or  im- 
pervious vessel  containing  some  of  the  germicidal  substance,  more  of 
which  is  added  afterwards,  and  the  mass  thoroughly  disintegrated  and 
mixed.  The  breaking  up  of  the  masses  and  mixing  is  best  done  with  a 
little  stick  which  is  then  dropped  into  the  mess.  The  mixture  should 
stand  at  least  two  hours  before  the  contents  are  disposed  of,  kept  well 
covered  meanwhile,  and  the  vessel  given  a  thorough  cleansing  and  disin- 
fection before  it  is  again  used.  At  least  an  equal  quantity  of  the  germi- 
cidal solution  should  be  used  to  the  mass  disinfected  and  enough  should 
always  be  added  to  entirely  submerge  all  particles.  Excreta  must  always 
be  protected  from  flies  and  other  insects,  even  while  undergoing  disin- 
fection. 

It  is  necessary  to  emphasize  the  importance  of  breaking  up  all  masses 
until  they  are  completely  disintegrated,  and  mixing  thoroughly  with  the 
germicide.  It  is  almost  impossible  for  any  of  the  ordinary  germicides 
to  penetrate  particles  of  even  moderate  size,  within  a  reasonable  timey 
emulsions  do  not  penetrate  at  all,  and  therefore  should  not  be  used  to- 
disinfect  feces. 


1172  METHODS  OF  DISINFECTION 

It  is  always  desirable  to  use  a  generous  excess  of  germicidal  agent, 
both  as  to  strength  and  amount,  in  disinfecting  feces.  The  following 
substances  and  methods  are  recommended : 

Lime  and  Hot  Watek. — A  simple  and  effective  method  for  the  dis- 
infection of  feces,  such  as  typhoid  stools,  consists  in  adding  enough  hot 
water  to  cover  the  mass  in  the  receptacle,  and  then  adding  about  i/4  of 
the  entire  bulk  of  quicklime,^  A  large  cup  of  lime  is  about  enough  for 
an  average  stool.  The  receptacle  should  then  be  covered  and  allowed 
to  stand  for  two  hours.  In  addition  to  the  germicidal  action  of  the  lime 
there  is  enough  heat  generated  by  the  hydration  of  the  lime  to  destroy 
typhoid  and  similar  microorganisms.  It  is  important  to  start  with  hot 
water  from  50°  to  60°  C.  and  the  mass  will  then  be  heated  throughout 
to  80°  or  90°  C. 

A  bucket  of  boiling  water  (about  1  gallon)  will  disinfect  a  single 
stool  when  other  germicidal  agents  are  not  obtainable.  The  vessel 
should  be  covered  and  allowed  to  stand  until  cool.  Sufficient  heat  is 
thus  had  to  destroy  practically  all  bacteria  except  the  spore  bearers. 

Milk  op  Lime. — Use  freshly  prepared  milk  of  lime  containing  1  part 
by  weight  of  the  freshly  slaked  lime  to  4  parts  of  water.  Add  at  least  an 
equal  quantity  to  the  amount  of  material  to  be  disinfected  and  allow  the 
mixture  to  stand  no  less  than  two  hours  before  final  disposal.  The 
perfunctory  sprinkling  of  fecal  matter  with  lime  or  milk  of  lime,  as  is 
often  done,  is  not  effective.  Lime  should  not  be  thrown  into  the  hoppers 
of  water-closets  for  the  disinfection  of  dejecta,  for  otherwise  a  thick 
mass  may  accumulate  and  obstruct  the  pipes.  In  disinfecting  excreta 
with  lime  the  reaction  of  the  resulting  mixture  must  be  alkaline  else 
the  object  will  not  be  attained. 

Lime  or  milk  of  lime  is  useful  for  the  disinfection  of  privies,  or 
trenches  in  camp,  or  in  country  practice.  For  its  use  under  these 
circumstances  the  amount  required  may  be  arrived  at  as  follows :  The 
amount  of  fecal  matter  per  person  is  reckoned  at  400  grams  a  day.  If 
the  urine  is  also  to  be  disinfected  this  may  be  counted  as  1,500  to  2,000 
c.  c.  per  person  daily.  For  the  disinfection  of  the  solid  excrement  alone 
50  grams  of  lime,  or  400  c.  c.  of  the  milk  of  lime  (1  to  8),  must  be  reck- 
oned for  each  person  per  day.  If  the  urine  is  included  it  will  take 
four  to  five  times  as  much.  The  mixture  must  have  an  alkaline  reaction. 
Attention  is  again  called  to  the  fact  that  air  slaked  lime  is  inert. 

Chlokinated  Lime.— This  is  one  of  the  most  useful  and  potent 
germicidal  substances  for  the  disinfection  of  feces.  Use  at  least  a  3  per 
cent.,  better  5  per  cent.,  solution  and  an  amount  equal  to  the  mass  to 
be  disinfected.     Thoroughly  mix  and  allow  to  stand  at  least  2  hours. 

*  Linenthal,  H.,  and  Jones,  H.  N. :  "A  Simple  and  Effective  Method  for 
Disinfection  of  Typhoid  Stools,"  Monthly  Bull.,  State  Bd.  of  Health  of  Mass., 
Jan.,  1914,  Vol.  9,  No.  1,  p.  50.     Boston  Med.  and  Surg.  Jour.,  Jan.  8,  1914. 


METHODS  OF  DISINFECTION"  1173 

Chlorinated  lime  is  rendered  inert  by  organic  matter;  therefore  an 
excess  should  always  be  used.  It  is  also  converted  to  the  inert  carbonate 
upon  exposure  to  the  air.     (See  page  900.) 

Formalin. — A  10  per  cent,  solution  of  formalin  may  be  depended 
upon  to  disinfect  feces  if  thoroughly  incorporated  with  the  mass  and 
allowed  to  stand  at  least  two  hours.  As  a  deodorant  it  acts  almost  in- 
stantly. 

Carbolic  Acid. — A  5  per  cent,  solution  of  crude  carbolic  acid  added 
to  an  equal  bulk  of  excreta  may  be  depended  upon  to  disinfect  in  two 
hours,  provided  the  germicide  is  thoroughly  incorporated  throughout 
the  mass. 

The  cresols  as  "tricresol"  and  liquor  cresolis  compositus  are  valuable 
agents  for  the  disinfection  of  fecal  matter  in  small  amounts  on  account 
of  their  energetic  action  and  because  their  efficiency  is  not  greatly  im- 
paired by  the  presence  of  albuminous  matter. 

Dry  earth  promotes  the  disinfection  of  excreta,  thus  delaying  putre- 
factive changes  while  absorbing  the  odors.  It  has  no  inherent  germi- 
cidal qualities. 

Corrosive  sublimate  is  not  well  suited  for  the  disinfection  of  feces 
and  sputum. 

Sputum. — The  discharges  from  the  mouth  and  nose,  not  alone  of  the 
sick,  but  of  well  persons,  are  often  laden  with  infection.  This  is  one  of 
the  frequent  means  by  which  disease  is  transferred.  The  proper  disposal 
of  sputum  and  its  efficient  disinfection  are  therefore  important  public 
health  measures  to  check  the  spread  of  tuberculosis,  diphtheria,  scarlet 
fever,  measles,  whooping-cough,  influenza,  tonsillitis,  common  colds, 
mumps,  chickenpox,  cerebrospinal  fever,  poliomyelitis,  sore  throat,  small- 
pox, pneumonia,  the  pneumonic  form  of  plague,  etc.  It  is  a  good  rule 
to  require  the  discharges  from  the  mouth  and  nose  of  all  patients  to 
be  received  upon  small  pieces  of  gauze  or  in  individual  cups  which  may 
subsequently  be  burned. 

Sputum,  when  in  considerable  quantities,  should  be  received  in 
paper  cups,  which,  with  their  contents  may  be  burned.  If  this  is  not 
practical,  it  may  be  received  in  ordinary  cups  containing  5  per  cent, 
carbolic  solution.  When  not  in  large  quantities  sputum  and  other  in- 
fective discharges  should  be  received  on  cheap  cloths  or  soft  paper  and 
promptly  burned.  If  handkerchiefs  are  used  they  should  be  immersed 
in  carbolic  solution  5  per  cent,  for  one  hour  before  they  are  laundered. 

The  most  truthworthy  chemical  disinfectants  for  sputum  are  carbolic 
acid,  5  per  cent.;  formalin,  10  per  cent,  or  stronger;  chlorinated  lime,  5 
per  cent.  The  methods  for  the  disinfection  of  sputum  correspond  to 
those  described  for  feces.  Sputum  offers  special  difficulties  on  account 
of  the  mucus  which  is  readily  coagulated  and  hard  to  penetrate. 

Sputum  should  be  kept  well  covered  in  suitable  receptacles  until  it 


1174  METHODS  OF  DISINFECTION 

is  disposed  of.  Simply  kcepiiif?  water  in  the  bedside  cups  or  in  cuspidors 
will  prevent  whatever  slight  danger  exists  in  the  dissemination  of  in- 
fection from  such  sources.  Antiseptic  solutions  may  be  used  for  this 
purpose,  but  are  not  necessary. 

The  disinfection  of  the  large  amounts  of  sputum  such  as  that  col- 
lected in  hospitals,  public  buildings,  and  other  places  is  a  difficult  and 
disagreeable  task.  On  account  of  its  dense  consistency  it  prevents  the 
penetration  of  chemical  solutions.  A  very  good  apparatus  for  the  disin- 
fection and  disposal  of  sputum  in  hospitals,  s'anatoria,  etc.,  consists  of  an 
autoclave  in  which  the  material  is  steamed  under  pressure  and  at  a  tem- 
perature of  120°  C;  after  the  completion  of  the  process  the  disinfected 
mass  is  washed  through  the  drain  into  the  sewer  by  water  entering  the 
autoclave.  The  entire  operation  can  thus  be  conducted  under  cover.  Dr. 
Wm.  J.  Manning  ^  describes  an  Ingenious  and  efficient  method  of  hand- 
ling spittoons  and  disposing  of  the  sputum  at  the  Government  Printing 
Office  in  Washington.  The  cuspidors  are  self -draining.  They  are  col- 
lected and  handled  by  devices  so  that  the  attendants  do  not  have  to 
handle  them  directly. 

Bed  and  Body  Linen. — Fabrics,  such  as  towels,  napkins,  handker- 
chiefs, sheets,  pillowslips,  and  similar  articles,  should  always  be  disin- 
fected after  contact  with  any  of  the  communicable  diseases,  for  they  are 
very  apt  to  become  infected.  They  may  be  steamed  or  boiled  or  im- 
mersed in  a  germicidal  solution  such  as  carbolic  acid,  5  per  cent.; 
formalin,  10  per  cent. ;  or  bichlorid  of  mercury,  1  to  1,000. 

Special  care  is  necessary  in  wishing  or  disinfecting  towels,  sheets, 
underwear,  and  other  fabrics  soiled  with  such  discharges  as  pus,  blood, 
or  excreta.  If  they  are  heated  or  boiled  without  special  precautions  they 
will  become  indelibly  stained  by  the  coagulation  of  the  albuminous  mat- 
ter which  becomes  fixed  in  the  fiber. 

Soiled  wash  may  be  treated  as  follows :  It  is  wrapped  in  a  sheet  wet 
vidth  sublimate  solution,  and  this  placed  in  a  sack  likev/ise  moistened 
with  a  germicidal  liquid.  The  sack  is  placed  unopened  in  a  solution 
containing  3  per  cent,  of  soft  soap  and  heated  to  50°  C.  for  three  hours 
and  left  in  the  same  solution  forty-eight  hours  after  it  cools.  If  not 
soiled  with  albuminous  matter  the  wash  may  be  immersed  in  a  solution 
of  bichlorid  of  mercury  1  to  1,000,  with  the  addition  of  common  salt. 
After  this  preliminary  disinfection  the  articles  are  boiled  half  an  hour 
in  a  water  containing: 

Petroleum 10  grams 

Soft  soap 250      " 

Water 30  liters 

Books. — With  the  exception  of  their  exposed  surface,  books  cannot  be 
disinfected  in  the  bookcase  or  on  the  shelves  of  houses  and  libraries. 
V.  A.  M.  A.,  Sept.  11,  1909,  Vol.  LII,  pp.  829-832. 


METHODS  OF  DISINFECTION  llYS 

However,  if  the  books  have  not  been  handled  or  exposed  to  infection  in 
any  way  except  by  their  presence  in  the  sickroom  there  is  no  reason  for 
considering  any  part  of  the  book,  except  the  exposed  surface,  as  infected. 
Such  books  may  be  disinfected  with  formaldehyd  gas  without  first  dis- 
turbing them  in  any  way. 

Books  which  have  been  handled  by  the  patient  or  which  have  been 
otherwise  exposed  to  infection  require  particular  care  in  their  disinfec- 
tion on  account  of  the  difficulty  of  penetrating  between  the  leaves.  Books 
used  in  public  libraries  are  often  regarded  with  suspicion,  and  many 
librarians  require  that  they  should  be  sunned,  aired,  or  disinfected  be- 
fore they  are  again  issued.  The  danger  from  this  source  has  doubtless 
been  exaggerated.  Books,  however,  which  have  been  handled  by  persons 
suffering  with  one  of  the  readily  communicable  diseases  should  always 
be  disinfected  before  they  are  again  used. 

Books  may  be  disinfected  in  a  specially  constructed  chamber  by  means 
of  heat  and  formaldehyd  gas.  They  must  be  arranged  to  stand  as  widely 
open  as  possible  upon  perforated  wire  trays.  Under  these  conditions  the 
exposure  should  be  continued  twelve  hours  with  high  percentages  of  for- 
maldehyd and  a  temperature  of  80°  C,  a  partial  vacuum  having  first 
been  introduced.  The  binding,  illustrations,  and  print  of  books  are  not 
injured  by  this  process. 

When  only  a  few  books  are  to  be  treated  in  the  absence  of  a  special 
apparatus  they  may  be  disinfected  by  placing  3  or  3  drops  of  a  40  per 
cent,  formalin  solution  on  every  second  page,  taking  care  to  distribute 
the  drops  well.  The  book  is  then  laid  in  a  close  box  or  drawer  in  whieli 
more  formalin  has  been  sprinkled,  and  left  in  a  warm  place  for  not 
less  than  twenty-four  hours. 

Pamphlets  and  unbound  volumes  may  be  steamed  without  serious 
harm.  Steam  is  not  applicable  to  the  disinfection  of  bound  books  on 
account  of  the  glue  and  leather. 

Beebe  ^  recommends  dipping  the  books  in  a  solution  of  carbolic  acid 
and  gasoline.  After  immersion  the  books  should  be  placed  before  an 
electric  fan,  which  rapidly  drives  off  the  gasoline. 

Nice  ^  recommends  the  use  of  moist,  hot  air  at  80°  C.  and  30  or 
40  per  cent,  humidity  for  thirty-two  hours  for  the  disinfection  of  books. 
This  is  said  to  destroy  all  non-spore-bearing  bacteria  in  closed  books, 
even  tubercle  bacilli  in  thick  layers,  without  injuring  the  most  delicate 
bindings. 

Cadavers. — Dead  bodies  may  be  the  cause  of  the  spreading  of  some 
of  the  communicable  diseases.  The  body  without  previous  washing 
should  be  wrapped  in  a  sheet  wet  with  a  strong  germicidal  solution,  such 
as  bichlorid  of  mercury,  1  to  500 ;  carbolic  acid,  5  per  cent.,  or  trikresol, 

^Jour.  Am.  Public  Health  Assn.,  Vol.  I,  No.   1,  p.  .'54,  Jan.,   1911. 
V.  A.  M.  A.,  April  20,  1912,  Vol.  LVIII,  No.  16,  p.  1201. 


1176  METHODS  OF  DISINFECTION 

1  per  cent.,  until  it  is  disposed  of.  Should  it  Ijg  desirable  to  wash  the 
body  it  should  be  done  with  formalin  (10  per  cent.)  or  Labarraque's 
solution,  or  one  of  the  germicidal  solutions  above  mentioned. 

From  a  sanitary  standpoint  bodies  dead  of  one  of  the  communicable 
diseases  are  best  disposed  of  by  burning.  When  cremation  is  not  prac- 
ticable the  body  may  be  surrounded  by  twice  its  weight  of  freshly  burnt 
lime  in  an  hermetically  sealed  coffin  and  buried  at  least  6  feet  under- 
ground. There  is  much  less  danger  from  the  spread  of  disease  from 
bodies  buried  in  the  ordinary  way  than  is  commonly  supposed. 

Embalming  with  strong  solutions  of  formalin  and  arsenic  that  are 
commonly  used  for  this  purpose  is  effective  in  destroying  all  but  the 
surface  infection. 

The  disposal  of  bodies  dead  of  anthrax  is  an  important  and  difficult 
matter  and  has  been  discussed  on  ]3age  315. 

Thermometers. — A  thermometer  may  be  the  source  of  conveying  dis- 
ease from  one  person  to  another,  and  it  behooves  the  physician  to  exer- 
cise special  care  concerning  its  cleanliness  and  disinfection.  The  best 
practice  is  to  keep  pure  formalin  or  70  per  cent,  alcohol  in  the  thermom- 
eter case  in  which  the  instrument  is  kept  constantly  bathed. 

Wells  and  Cisterns. — The  disinfection  of  a  well  may  be  accomplished 
by  the  use  of  freshly  burnt  lime.  About  half  a  barrel  is  thrown  into  the 
well,  stirred  up  with  the  water,  and  the  walls  are  scrubbed  down  with 
the  resulting  milk  of  lime.  The  well  is  then  pumped  out,  cleaned, 
allowed  to  refill,  and  a  second  supply  of  lime  added,  after  which  the  well 
is  allowed,  to  stand  twenty-four  hours.  After  a  thorough  stirring  the  so- 
lution is  then  pumped  out  and  the  well  is  allowed  to  refill  and  is  re- 
emptied  until  the  water  is  practically  free  from  lime.  Instead  of  lime 
chlorinated  lime  may  be  used  for  this  purpose,  sufficient  being  added  to 
make  approximately  a  1  per  cent,  solution. 


SECTION  XIII 
MILITARY  HYGIENE 

Military  efficiency  depends  upon  the  health  of  the  command.  Many 
military  disasters  have  been  due  to  disease.  Valor  and  patriotism  are 
seriously  handicapped  by  typhoid  fever,  dysentery,  malaria  and  other 
infections  which  in  years  past  have  sapped  the  strength  of  armies.  More 
soldiers  in  the  world's  history  have  succumbed  to  bacteria  than  to  bullets. 
Until  recently,  the  high  morbidity  and  mortality  rates  among  troops  have 
been  notorious.  It  is  only  in  recent  years  that  the  results  of  sanitary 
sciences  have  been  able  to  safeguard  the  soldier  and  sailor  against  many 
infections  that  formerly  decimated  the  ranks. ^  In  fact,  the  fruits  of  pre- 
ventive medicine  are  most  conspicuous,  picturesque  and  convincing  in 
armies  and  navies.  Formerly,  military  hygiene  dealt  principally  with 
the  surgery  of  wounds  and  the  treatment  of  fevers;  now,  however,  the 
larger  part  of  the  energy  and  skill  of  the  medical  corps  is  directed  toward 
their  prevention.  Therefore,  the  medical  officer  must  be  a  sanitarian  as 
well  as  a  physician  and  surgeon. 

The  first  successful  use  of  preventive  measures  on  a  large  scale  in 
modern  times  was  employed  by  the  Germans  in  the  Franco-Prussian  War 
of  1870-71. 

The  subject  of  camp  sanitation,  however,  is  not  new.  Thus  we 
read  in  Deuteronomy  "thou  shalt  have  a  place  also  without  the  camp 
whither  thou  shalt  go  forth  abroad,  and  thou  shalt  have  a  pad- 
dle upon  thy  weapon  and  it  shall  be  when  thou  shalt  ease  thyself 
abroad  thou  shalt  dig  therewith,  and  shalt  turn  back  and  cover  that 
which  cometh  from  thee."  If  the  above  primitive  injunction  had  been 
followed  by  our  troops  in  the  Spanish-American  War  it  would  have 

^The  conditions  during  our  Civil  War  are  thus  described  by  Charles  Francis 
Adams : 

"The  trouble,  however,  was  that  we  were  all  so  inexperienced,  and  knew 
nothing  of  the  laws  of  health  and  self-preservation,  and  we  thought  those 
laws  not  worth  knowing.  Why  any  of  us  survived  I  cannot  now  see,  but  we 
were  young  and  robust  as  a  rule,  we  lived  in  the  open  air  and  we  were  at  least 
temperate.  On  the  other  hand,  we  had  no  schools  of  instruction.  .  .  .  We 
were,  too,  encamped  in  low  lands  for  convenience  of  access  to  water  on  account 
of  the  horses.  .  .  .  With  a  suggestively  growing  sick  list,  it  never  occurred  to 
me  to  change  my  camp  to  higher  ground  or  dryer  soil,  to  put  my  men  in  mo- 
tion on  some  pretext,  or  to  alter  my  own  diet.  I  stupidly  blundered  along, 
myself  sickening  day  by  day.  .  .  .  These  simple  precautions  never  seemed  to 
suggest  themselves  to  our  army  medical  men."  "Autobiography  of  Charles 
Francis  Adams,"  pp.    146,   162,   and   163. 

1177 


1178  MTLTTAKY  HYGIENE 

saved  thousands  of  cases  of  sickness  and  deaths  from  typhoid  fever.^ 
Soldiers  are  notoriously  improvident,  indifferent  and  uninformed 
concerning  questions  of  health.  Constant  and  skilled  supervision  is 
necessary  over  food,  water,  clothing,  ammunition,  personal  hygiene  and 
safety.  Hence  instruction  in  the  essentials  of  military  hygiene  and  first 
aid  becomes  one  of  the  prime  duties  of  the  medical  corps. 

Military  hygiene  is  only  a  special  application  of  the  facts  and  prin- 
ciples of  general  hygiene,  applied  to  the  particular  conditions  of  camp, 
barrack,  field  and  march.  The  efficient  medical  officer  must  be  ac- 
quainted with  these  particular  conditions,  else  incompetency  is  bound  to 
result.  Training  of  the  medical  officer  for  military  service  is  therefore 
an  important  part  of  preparedness. 

In  campaign  the  objects  of  medical  administration  are  first  and  fore- 
most the  preservation  of  the  strength  of  the  army  in  the  field,  and  sec- 
ondarily the  care  and  treatment  of  the  sick  and  injured  at  the  front,  in 
the  line  of  communications  and  in  the  home  territory.  The  first  object 
is  obtained  by  an  application  of  all  sanitary  measures;  by  the  retention 
of  effectives  at  the  front  and  the  movement  of  non-effectives  to  the  rear 
without  obstructing  military  operations;  and  finally  by  the  prompt  suc- 
cor of  wounded  on  the  battlefield  and  their  removal  to  the  rear,  thus 
preventing  the  unnecessary  withdrawal  of  combatants  from  the  firing 
line  to  accompany  the  wounded,  and  promoting  the  general  morale  of 
the  troops. 

RECRUITS  AND  RECRUITING 

Nothing  is  more  mistaken  than  the  lay  idea  that  any  man  with  cour- 
age would  make  a  good  soldier,  A  suitable  recruit  must  not  only  be  able- 
bodied,  but  he  must  have  good  character,  mentality,  habits,  and  tem- 
perament. A  minor  physical  defect  may  under  the  strain  and  priva- 
tions of  a  campaign  not  only  incapacitate  him,  but  require  the  atten- 
tion of  several  useful  soldiers  in  taking  care  of  him.  Nor  does  the 
story  end  here,  for  later  he  may  secure  a  pension  from  a  government 
which  he  never  usefully  served.  This  is  too  commonly  the  case  with 
volunteer  troops  whose  standards  of  recruiting  are  below  that  of  regular 
troops. 

In  1900  the  admissions  for  disease  in  the  United  States  Army  per 
1,000  strength  were  1,821  regulars,  against  2,762  volunteers;  while  the 
mortality  was  12  and  25,  respectively.^ 

City  bred  men  make  better  soldiers  for  immediate  service  than  coun- 

*  One-third  of  our  entire  command  had  typhoid  fever.  There  were  about 
20.000  cases  and  .3,000  deaths  in  a  total  of  about  107,000  enlisted  officers  and 
men. 

^  "Military  Hygiene,"  by  Valery  Havard,  second  edition,  p.  172. 


EBCEUITS  AND  EECEUITINa  1179 

try  lads;  however,  the  latter  outstrip  the  former  after  a  year  or 
two  of  training.  Town  bred  men  are  quicker  to  understand  what  is 
required  and  hence  are  sooner  trained.  They  are  usually  immune  to 
measles,  whooping-cough,  mumps,  and  other  diseases  of  childhood, 
which  often  prevail  in  recruiting  camps,  and  are  apt  to  lower  the  stand- 
ard of  health  and  vigor  of  country  youths.  Eecruits  from  cities  are 
more  likely  to  be  familiar  with  some  technical  trade  which  is  of  value 
in  war. 

Only  1  in  3  to  4  applicants  is  accepted  at  the  recruiting  office,  and 
not  all  of  these  satisfy  the  rigorous  physical  examination  to  which  they 
are  subjected. 

The  physical,  moral  and  mental  standard  of  the  whole  army  depends 
upon  the  thoroughness  of  the  examination  of  the  recruiting  officer.  The 
rule  during  times  of  peace  is,  "if  in  doubt,  reject." 

Formerly,  examinations  were  made  by  civilian  physicians,  as  a  result 
of  which  practice  large  numbers  of  disabilities  came  to  light  in  recruits 
after  they  were  sworn  in.  Wherever  available,  medical  officers  of  the 
regular  army  are  now  required  under  present  regulations  to  examine 
recruits.  Line  officers  can  readily  pass  judgment  on  physical  defects 
such  as  flat  feet,  varicose  veins,  skin  eruptions,  defective  development  of 
parts;  on  venereal  diseases,  indecent  tattooing,  dirty  person,  etc.  The 
greatest  number  of  rejections  is  caused  by  venereal  diseases,  heart  dis- 
orders, defective  vision  or  hearing,  flat  feet,  and  poor  physique. 

So  important  is  the  physical  examination  of  recruits  regarded,  that 
a  manual  dealing  with  the  subject  has  been  authorized  by  the  govern- 
ment for  the  guidance  of  the  examining  officer. 

An  applicant  for  first  enlistment  must  be  a  citizen  of  the  United 
States,  between  the  ages  of  18  and  35  years,  of  good  character,  temperate 
habits,  able-bodied,  free  from  disease,  and  must  be  able  to  speak,  read  and 
write  the  English  language. 

Age. — The  age  limit,  except  when  unusual  numbers  are  drafted  for 
war,  is  between  18  and  35.  It  is  generally  recognized  that  youths  under 
22  cannot  stand  the  strain  and  privations  of  war.  Up  to  the  twenty-fifth 
year  growth  and  development  are  taking  place,  "the  bones  are  not  fully 
formed,  nor  have  they  reached  their  final  hardness;  the  epiphyses  have 
not  become  incorporated  with  the  shafts  of  the  long  bones;  the  joints 
are  not  fully  developed;  the  chest  has  by  no  means  attained  its  full 
capacity;  the  organs  of  the  body  in  general  are  immature."  (Harring- 
ton.) Napoleon  said  that  "boys  only  serve  to  fill  the  hospitals  and 
encumber  the  roadside."  Further,  young  men  are  more  susceptible  to 
many  infections,  both  on  account  of  youth  and  because  they  are  more 
careless,  reckless  and  inexperienced.  On  the  other  hand,  young  men  are 
quick  to  learn,  ready  to  act,  brave,  and  amenable  to  discipline.  Under 
eighteen  years  of  age  the  candidate  for  enlistment  must  have  the  consent 


1180 


MILITARY  HYGIENE 


of  parent  or  guardian.  European  countries  with  compulsory  military 
systems  require  service  at  about  the  age  of  twenty. 

Character  and  Mental  Condition. — These  are  determined  by  the  re- 
cruiting officer  so  far  as  possible  by  demeanor,  expression,  manner  of 
answering  questions,  absence  of  obscene  tattooing,  nature  of  glance,  etc. 
It  is  exceedingly  difficult  in  a  brief  examination  to  appraise  character. 
It  is  also  difficult,  but  very  important,  to  discover  degeneracy  or  mental 
unfitness.  The  medical  examiner  must  be  familiar  with  psychiatry. 
Mental  unfitness  is  often  more  disqualifying  than  physical  defects.^ 
Dementia  precox  is  the  most  important  mental  disease  from  the  stand- 
point of  military  service — feeble-mindedness  in  itself  is  not  so  serious 
a  factor.  Syphilis  and  heredity  are  the  underlying  causes  of  most  mental 
diseases.  Every  effort  should  be  made  to  detect  psychoneuroses,  epi- 
leptics, alcoholics,  and  drug  addicts. 

In  the  army  during  the  year  of  1913  the  discharge  rate  for  mental 
disease  was  higher  than  that  from  any  other  cause. 

Height,  weight  and  chest  measurements  are  recorded.  They  should 
conform  to  established  standards  and  bear  certain  definite  proportions 
one  to  another. 

TABLE  OF  PHYSICAL  PROPOimONS  FOR  HEIGHT,   WEIGHT,   AND  CHEST  MEASUREMENT 


Heig 

ht 

Weight, 
Pounds 

Chest  Measurement 

Feet 

Inches 

At  Expiration: 
Inches 

Mobility: 
Inches 

5     4/12 

64 

128 

32 

2 

5     5/12 

65 

130 

32 

2 

5     6/12 

66 

132 

321^ 

2 

5     7/12 

67 

134 

33 

2 

5     8/12 

68 

141 

33M 

2^ 

5     9/12 

69 

148 

33K 

2^ 

5  10/12 

70 

155 

34 

2H 

5  11/12 

71 

162 

34M 

2K 

6 

72 

169 

34M 

3 

6     1/12 

73 

176 

35M 

3 

Variations  from  this  standard  are  permitted  if  the  applicant  is  active, 
has  firm  muscles  and  is  evidently  vigorous  and  healthy. 

The  requirements  of  the  War  Department  (Circular  No.  1,  August  5, 
1913)  specify  the  minimum  height  for  infantry,  coast  artillery  and 
engineers  at  64  inches ;  for  cavalry  and  field  artillery  between  64  and  72 
inches ;  for  mountain  batteries  between  68  and  72  inches.  Foreign  coun- 
tries have  a  minimum  standard  of  less  than  62  inches,  save  Germany, 
62,  and  England,  64  inches. 

The  minimum  weight  for  all  branches  of  the  service  is  128  pounds. 

^  "Exclusion  of  the  Mentally  Unfit  from  Military  Service,"  Sheelian,  U.  8, 
Naval  Med.  Bull,  vol  X,  No.  2,'  April,   1916,  p.  213, 


EECPiUITS  AND  EECEUITING  1181 

The  maximum  for  infantry,  coast  artillery  and  engineers  is  190  pounds; 
for  cavalry  and  field  artillery,  165  pounds. 

Chest  measurements  are  obtained  at  the  end  of  forced  inspiration  and 
forced  expiration.  The  chest  girth  is  taken  by  means  of  a  tape  measure 
passed  around  on  a  line  including  the  lower  portions  of  the  scapulae,  and 
on  a  level  with,  or  just  below,  the  nipple.  Chest  measurements  do  not 
give  as  good  an  idea  of  the  respiratory  capacity  as  the  spirometer,  the 
use  of  which  has  not  yet  become  general  in  recruiting  offices.  The  rule 
in  the  United  States  Service  is  to  reject  men  who  measure  less  than  32 
inches  about  the  chest,  unless  specially  qualified  and  desirable.  For  men 
under  67  inches  in  height  the  difference  between  inspiration  and  expira- 
tion should  be  not  less  than  3  inches;  between  67  and  72  inches,  not  less 
than  2.5  inches;  72  inches  and  above,  not  less  than  3  inches.  The  chest 
capacity  or  "mobility"  is  one  of  the  best  indexes  of  vigor  and  endurance. 

Records.— As  a  protection  to  the  Government  in  the  future,  and  also 
as  a  matter  of  justice,  it  is  important  that  all  findings  of  the  recruiting 
officer  be  made  a  matter  of  permanent  record,  even  to  the  smaller  details. 
Minor  defects  may  become  the  basis  for  future  incapacity,  and  it  is  often 
important  to  know  whether  disabilities  were  contracted  "in  line  of  duty" 
— particularly  with  reference  to  pensions  and  discharges. 

Vaccination. — All  recruits  are  vaccinated  against  smallpox  and  are 
required  to  take  the  typhoid  prophylactic  inoculations. 

Under  special  circumstances  prophylactic  vaccines  against  cholera, 
plague,  paratyphoid,  dysentery  and  other  infections  are  used.  Poly- 
valent vaccines  may  be  used — that  is,  three,  four,  or  more  bacterial  vac- 
cines may  be  mixed  and  injected  at  the  same  time.  Thus  in  the  Serbian 
campaign  a  tetravaccine  was  used  consisting  of  typhoid,  paratyphoid  A 
and  B  and  cholera. 

General. — The  recruiting  officer  takes  into  account  the  cleanliness  of 
person  and  clothing.  The  examination  should  be  made  stripped.  The 
applicant  is  observed  while  walking,  running,  and  jumping.  Special 
examinations  are  made  of  the  lungs,  heart,  teeth,  skin,  joints,  and  feet; 
for  the  presence  of  hernia,  varicocele,  and  other  disqualifications.  Par- 
ticular attention  is  paid  to  the  condition  of  the  legs,  ankles  and  feet. 
Varicose  veins,  large  or  recent  bunions,  corns  on  the  sole,  flat  foot,  and 
"hammer  toe"  disqualify  the  applicant  for  marching  and  are  causes  for 
rejection. 

Eecruits  are  usually  examined  by  line  officers  at  recruiting  stations. 
The  medical  examination  is  then  done  at  recruiting  depots,  unless  a 
medical  officer  is  assigned  to  the  recruiting  station.  When  accepted, 
recruits  receive  preliminary  training  in  tactics  and  barrack  life.  A 
soldiers'  handbook  is  issued  to  them  in  which  is  discussed  the  articles  of 
war,  guard  duty,  rations,  clothing,  arms  and  equipment,  codes  for  sig- 
naling and  an  outline  of  first  aid  and  care  of  health. 


1183  MILITARY  HYGIENE 

DISEASES  OF  THE   SOLDIER 

The  diseases  of  the  soldier  do  not  difEer  from  those  of  the  civil  popu- 
lation. There  are  but  few  infections  peculiar  to  camp  and  field  life. 
Most  of  the  epidemics  of  camps  and  barracks  are  preventable.  In  former 
days,  soldiers  and  sailors  suffered  severely  from  the  results  of  over- 
crowding in  unsanitary  camps  and  barracks,  which  favored  the  spread  of 
all  communicable  infections,  especially  those  of  the  respiratory  tract,  the 
intestinal  tube  and  the  skin. 

The  most  frequent  diseases  of  soldiers  and  sailors  are  typhoid,  dysen- 
tery, '  diarrheal  diseases  and  other  gastro-intestinal  infections ;  pneu- 
monia, tuberculosis,  influenza,  common  colds,  sore  throat,  and  other 
inflammations  of  the  respiratory  tract;  measles,  mumps,  cerebrospinal 
meningitis,  scarlet  fever,  smallpox  and  other  infections.  At  times  the 
army  may  suffer  from  hookworm  disease,  especially  in  prison  camps  in 
southern  zones  where  proper  disposal  of  feces  is  not  practiced.  Dengue, 
yellow  fever,  cholera,  plague  and  typhus  fever  may  occur  as  epidemic 
outbreaks  among  the  troops.  Improper  rations  may  lead  to  beriberi  or 
scurvy;  campaigning  in  hot  weather  will  result  in  a  number  of  heat 
prostrations  or  even  in  sunstroke.  Soldiers  and  sailors  are  also  apt  to  be 
troubled  with  lice,  fleas  and  ticks;  skin  diseases  are  common  and  trouble- 
some. Conditions  affecting  the  feet  incident  to  marching  are  frequent 
and  important  (see  page  1202). 

All  the  preventable  diseases  above  mentioned  are  fully  treated  in 
other  portions  of  this  volume,  and  need  therefore  not  be  repeated 
here,  for  their  prevention  is  the  same  with  the  soldier  as  with  the 
civilian. 

The  diseases  transmitted  mainly  by  contact  find  favorable  conditions 
for  spread  in  camps,  barracks,  military  prisons,  and  on  board  ships. 
Therefore,  one  of  the  first  indications  in  checking  an  epidemic  is  to 
scatter  the  command  in  many  small  units  and  over  as  wide  a  territory 
as  practicable.  Measles,  mumps,  scarlet  fever  and  other  diseases  common 
to  childhood  are  very  apt  to  break  out,  especially  in  camps  recruited  from 
country  districts.  When  introduced,  these  diseases  spread  like  wild  fire 
among  the  susceptible. 

Mental  and  nervous  breakdowns  often  develop,  owing  to  the  strain 
and  unusual  conditions.  This  happens  in  persons  who  otherwise  would 
go  through  life  without  showing  signs  of  mental  derangement. 

Formerly,  tuberculosis  was  prevalent  in  armies  and  navies,  owing  to 
poor  ventilation,  overcrowding,  faulty  dietary,  exposure  and  ignorance; 
now,  however,  cases  are  recognized  early  and  segregated. 

Skin  diseases  of  a  communicable  nature  are  encountered,  such  as 
ringworm,  scabies,  dhobie  itch,  rhus  poisoning,  bites  of  vermin,  sand- 


ORGANIZATION"  OF  THE  MEDICAL  DEPAETMENT   1183 

flies  and  leeches.  According  to  Havard,  scabies  is  becoming  rare  among 
troops.  When  encountered  in  the  navy  it  affects  more  often  the  gluteal 
folds  and  dorsum  of  the  penis  than  the  handS;,  indicating  probably  its 
dissemination  by  infected  water  closets. 

Dhobie  itch  is  a  term  so  indefinitely  applied  that  it  has  deservedly 
fallen  into  disuse  among  medical  men.  It  is  still  the  popular  lay  term 
in  use  in  many  hot  countries  to  include  a  number  of  skin  diseases  which 
affect  the  axillae,  the  genitocrural  regions  and  parts  of  the  body  which 
come  in  contact  with  the  clothing.  Dhobie  itch  includes  chafing  (ery- 
thema intertrigo),  the  various  body  ringworms  (tricophytons),  pemphigus 
contagiosus  and  also  prickly  heat   (miliaria). 

Ehus  poisoning  is  another  annoying  skin  eruption  caused  by  poison- 
ing with  various  members  of  the  Ehus  family,  including  poison  ivy  and 
poison  oak.  The  hairs  with  which  the  plants  are  covered  contain  a  very 
irritating  oily  substance.  Actual  handling  of  the  plants  is  not  necessary, 
for  the  poisonous  hairs  are  shaken  off  and  carried  by  the  wind,  so  that 
susceptible  persons  are  often  poisoned  by  simply  passing  to  windward  of 
the  growth.  The  eruption  is  edematous,  inflammatory,  irritating  and 
very  annoying.  Some  persons  are  much  more  susceptible  than  others 
and  one  attack  appears  to  increase  the  susceptibility.  Trouble  may  be 
averted  even  after  handling  these  plants  by  the  free  use  of  soap  and 
water  and  alcohol,  but  the  application  must  be  thorough  or  else  it  will 
tend  to  spread  the  trouble. 

Sand  flies  and  leeches  are  most  annoying  in  the  tropics.  Sand  fleas, 
chigos  or  jiggers  are  flealike  insects,  and  the  gravid  female  burrows  in 
the  skin  of  any  part  of  the  body,  especially  the  soles  of  the  feet.  The 
insects  appear  as  small  black  or  red  specks  in  the  midst  of  a  blanched, 
tense,  shotlike  area,  which  may  become  as  large  as  a  small  pea.  The 
insects  may  be  removed  with  fine  forceps  or  a  pointed  instrument  when 
the  trouble  subsides. 

Leeches  (Hirudinea)  are  often  annoying,  especially  in  bathing  and 
fording.  So  far  as  known,  they  do  not  transmit  disease.  Land  leeches 
for  the  most  part  are  encountered  in  the  tropics.  Some  of  these  often 
penetrate  thick  clothing  to  reach  the  skin,  making  the  use  of  leggings 
and  shoes  imperative  where  they  abound.  The  bites  of  leeches  are  pain- 
less, and  through  secondary  infections  may  lead  to  ulcers. 


ORGANIZATION  OF  THE  MEDICAL  DEPARTMENT 

The  Medical  Department  of  the  United  States  Army  consisted  of  the 
Medical  Corps,  the  Medical  Eeserve  Corps,  the  Dental  Corps;  in  time 
of  war  volunteers ;  the  Hospital  Corps  and  Nurse  Corps ;  and  contract 
surgeons  employed  from  time  to  time. 


1184  MILITAEY  HYGIENE 

Under  existing  laws  there  were  ^  in  the  Medical  Department  504  offi- 
cers and  4,012  enlisted  men,  in  a  total  of  5,029  officers  and  81,932  en- 
listed men  in  all  branches  of  the  military  service  in  the  United  States 
and  its  dependencies.  This  ratio  is  about  5  medical  officers  to  1,000 
enlisted  men.  Under  the  provisions  of  the  new  Hay-Chamberlain  bill,^ 
there  will  be  in  the  Medical  Department  a  minimum  number  of  1,750 
medical  officers,  and  maximum  2,365,  with  10,500  minimum  and  14,100 
maximum  enlisted  men.  This  will  provide  at  least  7  medical  officers  for 
1,000  enlisted  men.  By  its  provisions,  also,  the  Hospital  Corps  ceases  to 
exist,  its  members  becoming  known  simply  as  enlisted  members  of  the 
Medical  Department.  The  Medical  Eeserve  Corps  also  ceases,  its  func- 
tions being  taken  over  by  an  Officers'  Reserve  Corps,  which  will  act  as  a 
reserve  supply  of  trained  officers  for  all  branches  of  duty  in  the  Medical 
Department  of  the  Army. 

The  following  are  the  grades  and  corresponding  rank  in  the  medical 
corps : 

Surgeon  General Brigadier  General 

Assistant  Surgeon  General Colonel 

Surgeon Major 

Passed  Assistant  Surgeon Captain 

Assistant  Surgeon First  Lieutenant 

The  medical  service  in  the  field  is  divided  into  service  with  mobile 
troops,  and  service  of  the  line  of  communications,  which  includes  all 
sanitary  organizations  not  accompanying  troops.  Those  accompanying 
troops  are  ambulance  companies  and  field  hospitals,  having  to  deal  more 
strictly  with  military  surgery  than  hygiene.  For  duty  in  the  field,  mem- 
bers of  the  Medical  Department  are  also  assigned  to  regiments  and  other 
units.  To  a  regiment  of  infantry  or  cavalry,  for  example,  there  are 
assigned  1  Surgeon  with  the  rank  of  Major,  3  assistants  with  the  rank 
of  Captain  or  Lieutenant,  and  24  enlisted  men.  A  similar  arrangement 
is  made  with  the  field  artillery,  engineers,  signal  corps,  etc.  In  addi- 
tion, there  are  accredited  to  a  Division  at  headquarters  1  Colonel  (Di- 
vision Surgeon)  1  Major,  and  1  Captain  or  Lieutenant,  with  7  enlisted 
men,  a  Lieutenant  Colonel   (Sanitary  Inspector)   with  1  enlisted  man. 

The  personnel  of  a  field  hospital  in  time  of  peace  is : 

1  major 

1  captain  or  lieutenant 

3  sergeants  first  class 

6  sergeants  and  corporals 

1  acting  cook 

26  privates  first  class  and  privates. 

^  Armif  and  Navy  Register,  June  10,  1916. 
^Effective   July'l,    1916. 


OPtGA^^IZATION  OF  THE  MEDICAL  DEPAETME>7T    1185 
Organization  op  the  Medical  Department  in  Campaign 

Department  chief  surgeons   (Post  hospitals) 
General  hospitals 

General  hospitals  at  camps  of  mobilization 
Convalescent  camps 

Recei\'ing  hospitals,  ports  of  disembarkation 
Home  I  Quarantine  stations 

territory      )  Hospitals  for  prisoners  of  war 
Supply  depots 

Hospital  trains  and  trains  for  patients  ' 
Rest  stations  on  railway  lines  '■ 
Hospital  ships  and  ships  for  patients 
Sanitary  inspectors 


SCRCEON- 
GkNF.RAIj 


Field 


[Field 

■I    army  chief 

[    surgeon 


Division 
chief 
surgeons 


Medieal  De-       1  Regimental  and  other  med- 
partment  >   ical  personnel  on  duty  with 

with  troops       J    line  organizations 


Medical  Units 


f  Director 
ambulance 


Director 
field  hospi- 
tals 

Reserve  med- 
ical supply 


Ambulance 
companies 


I  Field 

I    hospitals 


f  Transport  columns 

Rest  stations 

Evacuation  hospitals 
I/ine  of  Base  hospitals 

commu-  Contagious  disease  hospitals 

ni  cations       -j  Casual  camps  for  sanitary  troops 
chief  Convalescent  camps 

surgeon  Trains,  boats,  and  ships 

Base  medical  supply  depots 

Sanitary  squads 

Field  laboratories 

Manvnl  for  the  Mtdical  Department,  1911,  page.  173,   paragragh  560. 
1  These  organizations  may  be  used  in  the  zone  between  home  territory  and  field  army  as  well  as 
in  home  territory. 


The  personnel  of  an  ambulance  company  in  time  of  peace  is: 
1  captain 

1  lieutenant 

2  sergeants  first  class 

7  sergeants  and  corporals 
1  acting  cook 
44  privates  first  class  and  privates.^ 
On  the  march,  the  field  army  chief  surgeon  and  division  chief  sur- 
geons   should    accompany    their   respective    commanders,    and   acquaint 
themselves  with  the  topography  and  resoiirces  of  the  country,  so  far  as 
the  same  would  affect  the  care,  shelter,  transportation,  etc.,  of  the  sick 
and  wounded. 

Ordinarily,  the  regimental  medical  officers  march  as  follows :  the 
senior  with  the  regimental  commander  and  one  in  the  rear  of  each  bat- 
talion unit.  Each  medical  officer  is  accompanied  by  an  orderly.  The 
remaining  regimental  sanitary  personnel  usually  march  with  the  bat- 
talion units.  Each  regiment  is  followed  by  an  ambulance  from  the 
ambulance  train;  unless  otherwise  ordered,  these  ambulances  join  their 

^Manual  of  the  Medical  Department,   1911,   par.   149, 
39 


1186  MILITARY  HYGIENE 

trains  at  the  beginning  of  an  engagement.  If  a  regiment  operates  alone 
it  is  accompanied  by  three  ambulances. 

A  Division  of  Infantry  is  composed  of  at  least  three  Brigades,  each 
made  up  of  at  least  three  regiments.  A  regiment  contains  about  1,600 
men  on  a  war  footing.  A  Division,  then,  is  composed  of  from  15,000  to 
20,000  men.  On  the  staff  of  the  Division  is  the  Division  Surgeon,  who 
has  the  rank  of  Colonel,  and  with  him  the  Assistant  Division  Surgeon, 
ranking  as  Lieutenant  Colonel,  who  is  also  the  Chief  Sanitary  Inspector 
of  the  Division. 

Each  brigade  has  a  Brigade  Surgeon,  ranking  as  Lieutenant  Colonel, 
or  Major,  and  an  Assistant  Brigade  Surgeon,  ranking  as  Major,  who  is 
also  Brigade  Sanitary  Inspector.  Each  of  the  three  or  more  regiments 
making  up  a  brigade  has  a  Eegimental  Surgeon  ranking  as  Major,  and 
two  assistants,  ranking  as  Captains  or  First  Lieutenants.  In  addition  to 
the  above,  each  brigade  has  an  Ambulance  Company  of  12  ambulances 
and  72  enlisted  men,  war  strength,  officered  by  a  surgeon  with  the  rank 
of  Captain  and  two  Assistant  Surgeons  of  junior  grade. 

Each  division  also  has  a  field  hospital,  officered  by  a  surgeon  with 
the  rank  of  Major  and  nine  assistants  of  junior  grades,  and  manned  by 
10  non-commissioned  officers  and  51  privates  who  act  as  nurses  and 
attendants.  Each  regimental  infirmary  has  21  enlisted  men  who,  when 
on  the  march,  are  distriljuted  so  that  each  company  will  have  one  or 
two  men  to  render  first  aid. 

Begiments  are  assigned  three  medical  officers  each  so  that  each  of 
the  three  battalions  making  up  a  regiment  can,  in  case  of  divided  duty, 
have  its  own  medical  officer;  in  camp,  however,  one  medical  officer  to  a 
regiment  is  usually  considered  sufficient,  since  all  patients  are  trans- 
ferred to  the  hospital.  The  organization  for  artillery,  cavalry,  and  other 
branches  of  the  service  follows  the  same  general  lines  as  those  outlined 
for  the  infantry. 

The  above  outline  is  the  official  organization,  but  is  necessarily  elastic 
and  cannot  often  be  met  in  the  exigencies  of  actual  service. 

Duties. — The  duties  of  the  Medjcal  Officer  are  varied  and  often  exact- 
ing. They  include  both  preventive  and  curative  medicine.  In  general, 
the  duties  are :  to  look  after  the  health  of  troops  in  camp,  barracks,  and 
on  the  march;  attend  to  the  wounded  on  the  battlefield;  organize  and 
administer  hospitals,  ambulance  and  transport  service,  quarantine  sta- 
tions, medical  supply  depots  and  laboratories;  to  inspect  and  supervise 
the  quality  of  the  food  and  water;  to  instruct  officers  and  men  in  mili- 
tary hygiene  and  first  aid;  to  examine  recruits;  and  to  assist  both  stafE 
and  line  in  all  questions  involving  medicine,  surgery,  hygiene  or  sani- 
tation. 

An  Army  Medical  School  is  maintained  at  Washington  for  the  pur- 
pose of  instructing  the  officers  of  the  Medical  Department,  and  in  turn 


OEGANIZATIOX  OF  THE  MEDICAL  DEPAETMEXT    1187 


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1188  MILITAEY  HYGIENE 

the  members  of  the  Medical  Corps  give  general  instruction  in  military 
hygiene,  first  aid,  etc.,  to  officers  and  men  of  the  staff  and  line. 

The  duties  of  the  medical  officer  are  specified  in  regulations  which 
should  be  carefully  studied  and  followed.  The  regulations  in  the  Manual 
for  the  Medical  Department  are  only  part  of  the  general  body  of  reg- 
ulations with  which  the  medical  officer  must  acquaint  himself.  Obe- 
dience, uniformity,  and  discipline  are  essential  qualities  for  military 
efficiency. 

The  educational  duties  of  the  Medical  Department  are  of  a  twofold 
nature,  to  the  public,  and  to  the  military  services,  regular,  volunteer 
and  militia.  The  Surgeon-General's  Library  at  Washington  is  "the  great, 
central  medical  library  of  reference  of  the  Nation."  The  Medical  De- 
partment also  maintains  the  Army  Medical  Museum  and  an  Army  Med- 
ical School  in  Washington,  at  which  regular  courses  of  instruction  are 
given  to  medical  officers ;  and  an  Army  Field  Service  and  Correspondence 
School  for  Medical  Officers  at  Fort  Leavenworth,  where  courses  are  given 
to  the  Hospital  Corps  in  field  hospitals,  ambulance  companies,  and  de- 
tachments ;  also  the  teaching  of  hygiene  and  first  aid  to  the  Signal  Corps 
and  the  line. 

The  objects  of  medical  administration  in  campaign  are:  "First, 
preservation  of  the  strength  of  the  army  in  the  field — (a)  by  the  neces- 
sary sanitary  measures;  (b)  by  the  retention  of  effectives  at  the  front 
and  the  movements  of  non-effectives  to  the  rear  without  obstructing 
military  operations;  and  (c)  by  the  prompt  succor  of  wounded  on  the 
battlefield  and  their  removal  to  the  rear,  thus  preventing  the  unnecessary 
withdrawal  of  combatants  from  the  firing  line  to  accompany  the  wounded, 
and  promoting  the  general  morale  of  the  troops. 

"Second,  the  care  and  treatment  of  sick  and  injured  at  the  front,  in 
the  line  of  communications,  and  in  the  home  territory."  ^ 

The  duties  of  the  medical  department  are  officially  stated  as :  "the 
institution  of  sanitary  measures  to  preserve  the  health  of  the  troops  and 
inhabitants  of  occupied  territory,  the  care  of  sick  and  wounded,  their 
transportation,  etc.,  in  the  order  named." 

The  Chief  Surgeon  of  a  field  army  is  the  medical  and  sanitary  ad- 
visor of  its  commanding  officer.  He  has  charge,  under  the  commanding 
officer,  of  the  medical  administration  of  the  field  army  and  is  responsible 
for  the  proper  and  effective  management  thereof.  He  directs  the  distri- 
bution, instruction,  and  professional  supervision  of  the  entire  personnel 
of  the  Medical  Department  in  the  field  army.  He  also  directs  and  con- 
trols the  personnel  of  the  Bed  Cross  on  duty  at  the  front  and  on  the  line 
of  communications.  He  has  general  supervision  over  sanitary  measures 
and  provides  medical  attendance  at  army  headquarters.  He  devises  ap- 
propriate measures  for  shelter,  supplies,  treatment  and  transport  of  the 
^Manual  of  the  Medical  Department,   1911,  par.   .535. 


EATIO^-S  1189 

sick  and  wounded,  in  addition  to  a  number  of  other  duties^,  all  under  his 
commanding  officer. 

In  campaign  one  of  the  most  important  and  difficult  tasks  of  the 
Medical  Department  is  the  removal  of  the  sick  and  wounded  from  the 
front,  where  their  presence  would  hamper  military  operations ;  and  their 
transport  to  the  rear,  with  proper  safeguards  against  unnecessary  losses 
to  the  front.  This  comprises  the  collection  of  serious  cases  in  camp,  on 
the  march,  in  combat,  and  their  prompt  conveyance  to  places  where  they 
can  be  treated  with  due  regard  to  their  security  and  comfort.  In  select- 
ing places  for  evacuation  the  fundamental  principles  are :  that  the  com- 
batant forces  must  not  be  unduly  depleted,  the  medical  personnel  at  the 
front  unwarrantably  diminished,  and  the  transport  of  the  Medical  Depart- 
ment needlessly  taxed,  by  sending  to  the  rear  men  who  are  or  will  soon 
be  capable  of  effective  service  at  the  front.  The  sick  or  injured  should 
not  be  taken  farther  to  the  rear  than  is  warranted  by  their  condition 
and  prospects  of  recovery,  so  that  they  may  be  returned  to  their  units  at 
the  earliest  practicable  moment.  It  is  therefore  necessary  to  classify  the 
sick  and  wounded  according  to  the  nature  and  severity  of  their  disabil- 
ities. This  classification  should  be  begun  at  the  front  and  be  continued 
until  the  patients  are  returned  to  duty  or  reach  the  receiving  hospital  or 
other  distributing  point  in  home  territory. 

Local  provision  should  be  made  for  patients  unfit  for  transport,  in- 
cluding men  in  extremis,  and  for  cases  of  dangerous  infectious  disease. 
The  latter  should  be  evacuated  only  under  exceptional  conditions  and 
subject  to  special  precautions. 

For  the  removal  of  patients  from  the  front  to  the  rear,  litter  bearers, 
travois,  two-mule  litters  or  improvised  pack  animal  transports,  ambulance 
carts,  ambulances,  wagons  and  automobiles,  railway  trains,  and  hospital 
ships  or  boats,  or  all  of  these,  may  be  necessary,  according  to  circum- 
stances. 

RATIONS 

The  term  ration  means  "the  allowance  for  the  sustenance  of  one  per- 
son one  day."  The  ration  for  soldiers  and  sailors  in  the  United  States 
Army  and  ISTavy  is  fixed  by  congressional  act  and  cannot  be  altered  unless 
authorized  by  Congress.  The  ration  does  not  necessarily  represent  the 
diet  actually  issued  or  consumed,  for  parts  of  it  may  be  exchanged  for 
other  food  or  for  cash  with  which  to  buy  supplemental  articles  of  diet. 
Often  what  is  actually  issued  to  troops  in  active  service  depends  upon 
military  exigencies  and  the  operations  of  the  Commissary  Department. 

Garrison  Ration. — The  following  table  taken  from  "Tables  of  Organ- 
ization, United  States  Army,  1911,"  gives  the  ration  as  supplied  for 
Field  and  Supply  Trains : 


1190 


MILITARY  HYGIENE 


(When  ration  savings  privilege  has  been  suspended) 

[In  computing  the  carrying  capacity  of  vehicles  of  field  and  supply  trains,  the  weight 
of  a  ration,  including  containers,  is  taken  at  3  pounds.] 


A — Garrison  Ration  ^ 

B — Field  Ration 
(suggested) 

C— 

Components 

Substitutive  Equivalents 

(Actual  Issues) 

Re- 
serve 
Ration 

Articles 

Quan. 

Articles 

Quan. 

No.  1 

No.  2 

No.  3 

No.  4 

ounces 
20 

18 

.08 
2.4 

20 

1.28 

1.12 

3.2 
0..5 

.162 

.64 
.04 
.014 

.64 

.5 

.32  2 
.014 

ounces 

2Q   '  ' 

12 

16 

14 

18 

16 

16 

16'  " 

20 

18 

ounces 
\2" 

ie' ' ' 
i6' ' 

'i'28 
1.12 

'2^4' 

"  !l6 

ounces 
14 

16'  ■' 

'4' '  ■ 

14" 
5 

■l'2S 

1.12 
'2!4' 

"iie 
.02 

ounces 
14 

'z.h' 

ie" 
■4'  ■  ■ 

i4  " 
2 
2 

'  "384 
.128 
.128 
.64 

1.12 

■3!2' 

'"082 
.082 
.64 
.04 

"  !  64 

.  ounces 

ounces 

Mutton,  fresh 

\2" 

Canned  Meat 

Flour 

Fish,  pickled 

Fish,  canned 

Chicken  or  Turkey. . . 

Hard  Bread 

16 

Baking  Powder . . . 

...    . 

1.6 
1.6 

20 
20 

20 

'l!28 
1.28 
1.28 

Other   Fresh   Vegeta- 

.A-Pples,  evaporated  .  . 
Peaches,  evaporated  . 

Coffee,  roasted 
and  ground .... 

1.12 

Coflee,  green 

1.4 
.32 

2.4 

Milk,  evaporated . 

Pickles 

.16  2 

Salt 

.16 

Pepper,  black .... 

Other  Spices 

.14 

Butter 

Lard  Substitute 

.64 

Oleomargarine 

.  5 

"  !6i4 

Vanilla  Extract 

Approximate    net 
weight — lbs .... 

4.4 

4,5 

2.935 

3.85  3 

4.0 

1.98 

1  See  army  regulations  for  proportionate  issues  of  substitutive  equivalents  required  when  i.ssuing 
the  straight  garrison  ration. 

2  Gill. 

3  Or,  with  beef  supplied  daily,  2.97  pounds. 

Note. — The  suggested  field  ration  is  adaptable  as  follows: 
Nos.  1  and  2  for  use  of  troops  in  campaign. 
No.  1  embraces  all  components  of  the  ration. 
No.  2  contemplates  that  fresh  beef  and  fresh  vegetables  may  be  furnished   the   troops 

directly. 
No.  3  provides  a  more  varied  diet  and  is  adaptable  when  troops  are  located  near  depots 

of  supply. 
No.  4  (column  left  blank  for  notation). 
From  Tables  of  Organization,  U.  S.  A.,  1914. 

The  ration  is  flexible.     In  many  permanent  camps  and  barracks,  a 
supply  of  fresh  vegetables  may  1)e  obtained  by  truck  gardening. 

The  ration  must  take  a  large  number  of  factors  into  account.     First 


EATIOI^S 


1191 


of  all,  it  must  be  made  up  chiefly  of  the  standard  articles  of  food  to 
which  the  soldier  is  accustomed,  and  cooked  in  a  tasty  and  appetizing 
manner.  Thus  with  our  soldiers  the  chief  carbohydrate  staple  is  bread 
made  of  wheat  flour,  while  with  the  Japanese  and  Oriental  soldiers,  rice 
is  preferred.  Secondly,  the  ration  must  be  well  balanced  and  varied,  con- 
taining the  proteins,  fats  and  carbohydrates  in  proper  proportions; 
thirdly,  the  caloric  value  of  the  ration  must  be  svifficient  to  support  a 
man  at  hard  labor.  This  is  estimated  at  about  5,000  calories.  Further, 
the  ration  should  contain  antiscorbutic  articles,  such  as  fresh  fruits  and 
vegetables,  lime  juice,  onions  and  potatoes.  Finally,  care  should  be  taken 
that  the  dietary  contains  foods  rich  in  vitamines. 

Experience  has  shown  that  a  company  mess  is  better  than  a  regi- 
mental mess.  Each  company  of  100  men  will  require,  in  garrison,  a 
mess  staff  of:  one  non-commissioned  officer,  a  first  and  second  cook,  one 
or  two  cook  police,  and  one  dining-room  orderly.  Trained  cooks  are 
necessary  for  the  comfort  and  health  of  the  command,  and  a  training 
school  is  maintained  by  the  United  States  Army  for  this  purpose. 

The  United  States  field  ration  essentially  is  bacon,  canned  meat, 
fresh  or  hard  bread,  beans,  coffee  and  sugar,  and  is  the  main  reliance  of 
a  field  force.  It  is  supplemented  by  what  can  be  obtained.  This,  with 
its  supplementary  list,  is  regarded  as  one  of  the  most  liberal  of  any 
country. 

Reserve  rations  consist  in  the  main  of  bacon,  hard  bread,  coffee,  sugar 
and  salt.  They  are  used  only  when  field  rations  are  not  obtainable,  and 
then  only  by  order  of  the  commanding  officer.  Each  man  carries  in  his 
kit  two  reserve  rations.  The  field  trains  carry  two  field  rations  and  one 
reserve,  and  the  supply  trains  two  more  field  rations  for  each  man.  A 
command,  then,  can  exist  a  week  on  its  own  supplies  if  it  leaves  its  line 
of  transportation  or  the  latter  fails. 

The  Haversack  ration  is  as  follows: 


HAVERSACK   RATION 


Component  Articles  and  Quantities 


Substitutive  Articles  and  Quantities 


Bacon 

Hard  Bread 

Coffee,  roasted  and  ground 

Sugar 

Salt 

Pepper,  black 


ounces 
12 
16 
1.12 
2.4 
.16 
.02 


[Varies  with  circumstances] 


Travel  rations  are  issued  in  place  of  the  ordinary  ration  when 
troops  travel  otherwise  than  by  marching,  or  when  for  short  periods  they 
are  separated  from  cooking  facilities  and  do  not  carry  cooked  rations. 


1193 


MILITAEY  HYGIENE 


It  consists  of  the  following  articles  and  is  issued  in  the  amounts  stated, 
per  hundred  rations : 


TRAVEL   RATION 


Component  Articles  and  Quantities 

Substitutive  Articles  and  Quantities 

ounces 

18 

12 
4 
8 

1.4 
1.12 
2.4 

.5 

Hard  bread 

ounces 
16 

Beef,  corned 

Beans  baked 

Hash,  corned  beef 

12 

Coffee,  roasted  and  ground 

Sugar 

Milk,  evaporated,  unsweet- 
ened 

On  arrival  at  their  destination  the  ordinary  ration  is  resumed. 

When  traveling  unaccompanied  hy  an  officer,  each  man  may  be  al- 
lowed a  cash  sum  per  day  for  the  purchase  of  liquid  coffee  in  place  of  the 
coffee  and  sugar  portion  of  the  travel  ration. 

The  Filipino  scout  ration  is  an  attempt  to  cater  to  the  customs  of 
the  natives  who  form  this  admirable  organization.  Since  unpolished  rice 
has  been  substituted  for  highly  milled  rice,  and  the  ration  has  been  better 
balanced,  beriberi  no  longer  exists  among  the  Filipino  scouts  (see  page 
652). 

The  French  ration  in  use  before  the  present  war  has  been  greatly 
augmented.^  Fresh  meat  is  obtained  from  "slaughter  parks"  which  have 
been  established  for  entire  corps,  as  far  as  75  kilometers  to  the  rear. 
This  is  made  possible  by  the  great  cruising  radius  of  fast  autotrucks. 

The  first  ambulant  or  rolling  kitchens  for  troops  were  used  by  the 
Russians.  Other  nations  have  been  quick  to  realize  their  usefulness. 
Many  other  useful  tricks  have  also  been  learned  from  the  American 
circus. 

Both  the  French  and  British  have  one  field  kitchen  for  about  100 
men,  which  is  situated  as  near  as  practicable  to  the  trench  entrance.  The 
French  troops  are  served  large  quantities  of  coffee  every  day ;  the  British 
prefer  tea.  The  use  of  alcohol  varies  with  different  nations.  Alcoholic 
drinks  were  formerly  issued  to  both  our  soldiers  and  sailors;  this  has 
long  ceased,  and  alcoholic  beverages  are  not  even  allowed  on  navy  vessels. 

In  the  army  the  sale  of  alcoholic  drinks  is  forbidden  in  the  canteen, 
which  was  the  soldier's  club.  The  canteen  itself  was  abolished  and  the 
name  changed  to  post-exchange.  The  advisability  of  re-establishing  the 
canteen  and  permitting  the  soldiers  to  have  beer  and  light  alcoholic 
beverages  is  much  discussed. 

In  our  army,  as  well  as  with  other  wliitc  troojjs,  fresh  bread  is  a  very 

*  Fauntleroy,  "The  Medico-Military  Aspects  of  tlie  European  War,"  1915. 


PiATIONS  1193 

important  article  of  diet.  When  bread  is  not  obtainable,  biscuits,  "field 
bread"  with  very  thick  crust,  or  hard  tack  (pilot  bread)  is  substituted. 

Potatoes  and  onions,  on  account  of  their  keeping  qualities,  are  the 
staple  fresh  vegetables  .with  our  troops.  Nearly  all  armies  use  some  forms 
of  dried  fruits  and  vegetables.  While  lacking  somewhat  in  flavor,  these 
articles  make  splendid  additions  to  the  ration,  and,  of  course,  are  less 
heavy  and  bulky  than  the  corresponding  fresh  substances. 

Milk,  as  supplied,  is  condensed — both  sweetened  and  unsweetened. 
Under  exceptional  circumstances,  a  fresh  supply  may  be  had  from  a 
nearby  dairy,  but  this  should  always  be  pasteurized. 

The  emergency  ration  consists  of  a  condensed  or  concentrated  mix- 
ture of  foods  which  have  a  high  nutritive  and  calorie  value  in  small 
bulk  and  weight.  Tastiness,  variety,  ease  of  preparation,  and  assimila- 
tion are  also  important  considerations  in  an  emergency  ration. 

An  "emergency  ration"  furnished  the  U.  S.  Army  in  addition  to  the 
regular  ration,  and  not  to  be  opened  nor  used  when  regular  rations  are 
obtainable,  has  the  following  composition : 

45.15  per  cent,  chocolate  liquor 


7.37 

ii 

« 

nucleocasein 

7.27 

iC 

iC 

malted  milk 

14.55 

cc 

id 

egg-albumin 

21.82 

iC 

cc 

powdered  cane  sugar 

3.64 

<l 

u 

cocoa  butter 

Percentage  of  moisture  not  to  exceed  3  per  cent. 

Each  ration  weighs  8  ounces  net  and  is  put  up  in  three  cakes  of 
equal  size,  each  cake  wrapped  in  tin  foil,  and  all  three  enclosed  in  a 
hermetically-sealed,  round-cornered  tin,  with  key-opening  attachment. 

There  is  now  supplied  the  concentrated  mess  known  as  pemmican, 
composed  of  dried  lean  beef,  tallow,  currants  and  sugar,  compressed  in 
cakes,  together  with  cakes  of  chocolate.  Pemmican  has  a  high  caloric 
and  nutritive  value  in  small  bulk  and  weight.  It  has  been  used  by 
arctic  explorers. 

The  British  emergency  ration  formerly  contained  chocolate  and  a 
milk  product.  Now  it  consists  of  a  small  tin  cylinder  weighing  about 
twelve  ounces,  containing  four  ounces  of  concentrated  beef  and  five 
ounces  of  cocoa  paste.  This  is  regarded  as  enough  to  keep  a  man  for  36 
hours. 

The  German  "iron  ration"  consists  of  biscuit,  preserved  meat,  pre- 
served vegetable  and  coffee.    It  Aveighs  one  and  one-half  pounds. 

The  Japanese  iron  ration  comprises  cooked  rice  and  meat,  with  a 
supplementary  article  of  diet. 

Many  "concentrated"  foods  have  been  investigated  and  found  want- 
ing.     The   question   of   variety,    vitamines,    caloric    value,    indigestible 


1194  MILITARY  HYGIENE 

"waste,"  and  other  factors  must  be  taken  into  account,  even  in  an  emer- 
gency ration. 

The  diseases  directly  caused  by  a  faulty  ration  are  scurvy,  beriberi 
and  pellagra.     These  have  all  been  discussed  in  other  parts  of  this  book. 


SANITATION  IN  CAMP  AND  ON  THE  MARCH 

PERSONAL   HYGIENE    OF    THE   SOLDIER 

The  March. — Troops  marching  in  close  formation  suffer  from  so- 
called  "crowd  poisoning" — believed  to  be  due  mainly  to  heat  and  humidity, 
aggravated  by  dust.  (See  page  685.)  It  is  now  customary  in  nearly  all 
armies  to  present  as  wide  a  front  as  possible  while  on  the  road;  usually 
two  columns  march  along  the  sides  of  the  road,  leaving  a  ventilating  isle 
down  the  middle.  Much  of  the  fatigue  and  hardships  of  marching  have 
in  recent  times  been  relieved  by  the  nse  of  autotrucks  and  troop  trains. 

The  "route  step"  is  used  on  the  march — that  is,  each  man  uses  the 
step  to  which  he  is  accustomed.  For  ordinary  marching,  the  step,  accord- 
ing to  the  United  States  Eegulations,  is  at  the  rate  of  90  per  minute, 
each  30  inches  long,  or  2.5  miles  per  hour.  Quick  time  moves  at  the  rate 
of  120  such  steps,  or  3.4  miles  per  hour;  double  time  is  180  steps,  each 
35  inches  long,  or  six  miles  per  hour.  The  figures  for  other  countries 
are  in  general  similar  to  our  own.  The  rate  of  march  is  influenced  by 
the  character  of  the  roads  or  ground  covered,  as  well  as  by  head  winds, 
storms,  great  heat  or  snow. 

Marching  at  night,  save  for  tactical  reasons,  and  marching  in  the 
hottest  part  of  the  day  should  be  avoided.  The  command  should  have  a 
light  breakfast  before  starting.  Halts  should  be  arranged  by  hours 
rather  than  by  bugle,  since  the  different  rates  of  travel  frequently  allow 
the  head  of  the  column  to  finish  its  rest  before  the  rear  has  caught  up. 
The  head  of  the  column  should  be  taken  in  turn  by  the  various  com- 
panies. The  first  halt  usually  occurs  during  the  last  fifteen  minutes  of 
the  first  hour,  to  give  the  men  a  chance  to  relieve  themselves,  re-adjust 
clothing,  cinches,  etc.  All  other  halts  during  the  day  are  usually  about 
ten  minutes  for  infantry,  five  minutes  for  cavalry,  and  five  to  ten  minutes 
for  artillery,  except  the  noon  rest,  which  should  be  at  least  an  hour. 
During  halts,  the  men  should  be  encouraged  to  lie  at  full  length  on  the 
ground,  utilizing  such  shelter  as  the  place  affords,  and  in  the  case  of 
foot  soldiers,  to  knead  the  buttocks  and  thighs  to  assist  in  muscular 
recuperation. 

When  a  "halt  order"  is  given,  proper  officers  of  the  quartermaster's 
and  medical  corps  should  accompany  the  officer  detailed  to  go  ahead  to 
select  a  camp  site,  procure  supplies  and  forage,  investigate  the  water. 


SANITATION  IN  CAMP  AND  ON  THE  MAECH        1195 

etc.  The  medical  officer  carries  bis  notebook,  in  wbicb  is  recorded  tbe 
choice  of  camp  sites,  with  a  sanitary  survey  embracing  observed  data  of 
importance,  as  well  as  all  other  items  of  medical  interest  from  day  to  day. 

Discipline  and  Sanitation. — The  two  essentials  of  good  marching 
are  discipline  and  sanitation.  Troopers  should  not  be  allowed  to  leave 
the  column  without  permission.  Those  who  fall  out,  or  desire  to,  should 
be  examined  by  a  medical  officer  and  a  sympathetic  watch  kept  to  prevent 
malingering.  Places  for  latrines  at  halts  are  designated  where  the  shal- 
low "straddle  trenches"  are  required  to  be  used,  covered  with  earth  and 
marked  on  leaving.  Water  for  daily  use  should  be  boiled,  filtered  or 
treated  with  "bleach"  the  night  before.  In  the  tropics  each  man  should 
be  supplied  two  canteens,  on  account  of  increased  loss  through  perspira- 
tion. Soldiers  should  be  encouraged  to  drink  as  little  water  as  possible 
while  on  the  road.  A  seasoned  soldier  conserves  the  supply  in  his  water 
bottle.  The  men  should  be  instructed  in  the  advantages  of  using  a  little 
water  as  a  mouth-wash,  followed  by  a  few  swallows;  also  in  the  use  of 
pebbles  and  chewing  grass  to  prevent  the  sensation  of  thirst. 

Bathing  is  very  important,  especially  for  foot  soldiers.  All  troops 
should  wash  the  face,  neck  and  feet  as  well  as  the  genital  and  axillary 
regions  with  a  damp  towel  with  soap,  each  morning  and  evening.  Daily 
baths  are  advisable  in  permanent  camps;  tubs  and  showers  can  be  ar- 
ranged with  pails  and  makeshifts  wnth  very  little  trouble  and  are  much 
appreciated  by  the  men. 

An  army  literally  marches  on  its  feet  as  well  as  "on  its  belly" ;  there- 
fore, the  care  of  the  feet  should  be  a  matter  of  gravest  concern  to  officers 
and  men.  (For  shoes  and  their  selection,  see  page  1202.)  Eegulations 
require  that  foot  soldiers  bathe  the  feet  daily  at  the  end  of  the  march 
in  cold  water,  but  only  long  enough  to  cleanse  the  skin  and  set  up  an 
invigorating  reaction.  Clean  socks  should  be  donned  daily  and  those 
removed  washed  out  to  dry  over  night.  Extra  socks  are  carried  as  part 
of  every  man's  equipment.  If  possible,  the  shoes  should  be  changed 
every  few  days  for  the  extra  pair  in  the  wagon  train.  If  rubbing  or 
creases  have  been  felt,  the  socks  should  be  turned  inside  out  or  changed 
to  the  other  foot  during  the  halts.  If  blisters  or  excoriations  occur  the 
serum  may  be  squeezed  out  and  the  area  protected  with  adhesive  plaster. 
Abraded  areas  may  be  greased.  As  a  rule,  practice  marches  will  have 
been  given  raw  troops  to  toughen  the  feet,  which  may  be  fortified  by  a 
daily  soaking  in  an  alum  bath  or  in  dilute  alcohol.  Often,  however, 
foot  troubles  will  arise  in  experienced  troops;  when  this  happens,  they 
should  be  treated  as  above  outlined.  Sometimes  the  feet  are  soaped  in 
the  morning  to  lessen  friction.  A  dusting  powder  composed  of  talcum 
87  per  cent.,  starch  10  per  cent.,  and  salicylic  acid  3  per  cent,  is  supplied 
and  may  be  shaken  into  the  socks  and  shoes.  The  use  of  a  dusting 
powder  is  usually  preferred  to  that  of  other  expedients.     In  some  coun- 


1196 


MILITAKY  HYGIENE 


tries  socks,  which  are  not  issued  to  the  troops,  are  substituted  wholly  by 
grease,  or  by  bandages,  or  strips  wound  around  the  feet,  either  greased, 
dry  or  dusted  with  powder.    The  men  should  be  taught  to  cut  their  toe 

jJ9,8Acfe^  « 

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Fig.  169. — Camp  of  a  Regiment  of  Infantry.     War  Strength.     (Field  Service  Rge- 

ulations,  U.  S.  A.,  1914.) 


nails  across  squarely,  as  this  tends  to  prevent  ingrown  toe  nails  and  other 
troubles. 

The  care  of  the  teeth  is  important.  The  soldier  should  be  required 
to  give  them  daily  attention  with  brush  and  powder. 

While  in  camp  the  soldier  must  look  to  his  own  laundry.  If  a  stream 
is  not  available  the  clothes  may  be  boiled  in  camp.     Only  within  recent 


EQUIPMEIsTT  1197 

years  have  places  for  laiuiclcring  been  j)roYicled  iu  garrisons.  Before 
1908,  our  soldiers  were  required  to  have  their  laundry  done  outside  of 
the  post,  or  do  it  themselves — a  measure  which  Avas  anything  but  satis- 
factory. 

The  choice  of  camp  sites  should  be  governed  by  the  presence  of  high 
ground,  proximity  of  water  and  a  supply  of  wood.  Tents  should  be 
ditched.  It  is  important  to  air  and  sun  the  tents  daily  by  raising  the 
walls ;  it  is  also  useful  to  move  them  a  few  feet  to  a  new  site  so  that  the 
sunshine  may  dry  and  purify  the  old  site;  it  is  desirable  while  on  the 
march  to  avoid  recently  used  sites,  since  old  latrines  may  be  opened  up. 

Moving  commands  bury  or  burn  their  excreta  and  garbage.  In  camp 
each  company  has  its  own  latrines  for  excreta  and  garbage,  sometimes 
two  of  the  former,  which  should  be  covered  and  marked  on  leaving. 

Tents  take  many  shapes  and  are  of  many  sizes,  according  to  the  uses 
to  which  they  are  intended.  The  tent  now  most  in  favor  with  our  army 
is  an  oblong  A-wall  tent.  Modifications  of  this  general  design  are  fur- 
nished for  the  mess  tents,  hospital  tents,  and  also  for  use  in  the  tropics- 
Tent  flies  make  the  tent  cooler  in  summer  and  protect  against  rain  and 
storms. 

The  general  plan  of  a  camp  is  shown  in  Figure  169.  The  kitchens 
are  placed  as  far  as  possible  from  the  latrines,  and  the  latrines  are  placed 
at  least  50  yards  from  the  men. 

Sanitary  Police. — Each  company  commander  in  turn  is  "officer  of 
the  day,"  and  as  such  is  responsible  for  camp  sanitation.  The  effective- 
ness with  which  policing  is  done  depends  largely  on  discipline.  The 
officer  of  the  day  and  his  detail  look  after  the  proper  use  of  latrines, 
the  proper  care  of  night  urine  tubs  and  their  lanterns,  their  proper 
cleaning  and  storage  during  the  day,  the  proper  disposal  of  all  refuse, 
paper,  and  in  general  the  cleanliness  and  orderliness  of  the  camp.  It 
is  evidence  of  poor  discipline  as  well  as  a  danger  and  disgrace  when  a 
camp  is  fringed  with  fecal  deposits  and  trash.  The  sanitary  inspection 
should  be  thorough  and  complete.  Often  it  becomes  advisable  to  have 
the  entire  sanitary  police  under  the  control  of  the  chief  surgeon  in  order 
to  abolish  nuisances. 

Sick  call  is  usually  sounded  after  arriving  in  camps,  and  in  fixed 
camps  usually  at  5  p.  m. 

EQUIPMENT 

The  soldier's  equipment  includes  his  arms  and  accoutrements,  cloth- 
ing, and  all  other  things  necessary  for  his  comfort  and  health.  All 
articles  of  equipment  must  be  of  good  quality,  of  greatest  strength  and 
best  wearing  power,  with  the  least  possible  weight.  There  then  remains 
the  very  important  problem  of  distribution  on  his  person  so  as  to  be 


1198 


MILITARY  HYGIENE 


carried  with  the  minimum  muscular  exertion  and  fatigue.    In  all  armies 
this  problem  is  given  much  attention. 

German  experiments  applied  to  the  respiratory  capacity  of  soldiers 
have  shown  that  their  loads  including  overcoats  should  seldom  exceed  55 
pounds.     The  weight  of  the  equipment  of  various  nations  is  as  follows: 

United  States  of  America,  new  equipment 48  pounds 

old           "            56  " 

Italy 58  " 

France 57  " 

England 52 

Germany 59  " 

Austria 61  " 

Russia 60  " 

Japan 55  " 


The  above  weights  are  approximate,  varying  according  as  the  over- 
coats, trenching  tools,  shelter  tents,  etc.,  may  be  temporarily  discarded. 
It  is  important  that  the  weight  be  divided  so  that  unnecessary  articles 
can  readily  be  detached  before  going  into  battle,  or  where  transportation 
is  available.  The  haversack  was  discarded  in  1908  in  our  army  and  its 
place  taken  by  a  blanket  roll.  This  in  turn  was  replaced  by  a  pack 
arrangement,  wherein  weight  is  distributed  over  the  soldier's  back  with 
the  least  disturbance  to  center  of  gravity,  thereby  saving  extra  muscular 
exertion. 

The  weight  of  the  United  States  equipment  is  divided  as  follows : 

TABLE    OF   ARTICLES   OF   EQUIPMENT,    WITH   WEIGHT   OF   EACH    (Keefer) 


Pounds 

Ounces 

Clothing  (with  extra  pair  socks) 

7 
9 
5 
1 
2 
1 

3 

1 

3 
2 
3 
1 

4 

13 

Rifle  and  sUng .                  .        

.92 

100  cartridges      .              

15.88 

Cartridge  belt                                        

6.1 

Trenching  tool 

2.04 

Bayonet  and  scabbard 

5.48 

First  aid  pack  and  pouch 

5.59 

Canteen  filled  with  cup  and  cover 

10.03 

Haversack.                                                 

9.85 

Pack  carrier .                                                  

7.32 

Blanket 

1. 

Shelter  tent  half  with  5  pins               

11.68 

Poncho ....              .                                

Meat  can,  knife,  fork  and  spoon                

1.21 

Rations  (2  reserve)  with  containers,  1  bacon  can,  1  con- 
diment can                                               

1.72 

Toilet  articles:  towel,  soap,  comb,  tooth  brush 

7. 

48 

2.83 

This  equipment  is  so  divided  that  shelter  halves,  etc.,  can  be  dis- 
carded before  going  into  battle,  thus  reducing  the  total  weight,  Avhich, 


EQUIPMENT  1199 

with  two  extra  bandoleers  of  cartridges,  brings  the  weight  to  39  pounds. 

In  wagon  trains,  there  is  carried  for  each  man  an  undershirt,  a  pair 
of  drawers,  two  pairs  of  woollen  socks,  a  pair  of  shoes  with  extra  laces, 
sweater  and  mosquito  bar. 

The  first  aid  packet  has  done  much  to  reduce  mortality  from  wound 
infections. 

The  First-aid  Packet. — When  a  ball  enters  or  goes  through  the  mus- 
cles or  soft  parts  of  the  body  alone,  generally  nothing  need  be  done  except 
to  protect  the  wound  or  wounds  with  the  contents  of  the  first-aid  packet. 

Each  packet  contains: 

(1)  Two  bandages  of  absorbent  sublimated  (1:1000)  gauze,  4  by  84 
inches. 

(2)  Two  compresses  of  absorbent  sublimated  (1:1000)  gauze,  each 
composed  of  I/2  square  yard  of  gauze,  folded  so  as  to  make  a  compress 
33/^  by  7  inches. 

(3)  Two  No.  3  safety  pins  wrapped  in  waxed  paper. 

The  packet  thus  prepared  is  placed  in  an  hermetically  sealed  metal 
case  with  a  suitable  arrangement  for  easy  opening.  All  contents  of  the 
case  must  be  sterile.  Dimensions  of  the  case  should  not  exceed  4  by  2^4 
by  16  inches. 

The  words  "First-aid  packet.  U.  S.  Army,"  are  stamped  on  the  metal 
case.  Also  directions  for  opening,  manufacturer's  name,  and  date  of 
contract. 

The  shell-wound  dressing  consists  of :       - 

(1)  One  compress  composed  of  1  square  yard  of  absorbent  sublimated 
(1:1000)  gauze,  so  folded  as  to  make  a  pad  6  by  9  inches. 

(2)  One  bandage,  3  inches  wide  by  5  yards  long,  of  absorbent  sub- 
limated (1:1000)  gauze,  loosely  rolled  and  wrapped  in  parchment  or 
waxed  paper. 

(3)  Two  No.  3  safety  pins  wrapped  in  waxed  paper. 

The  whole  dressing  is  wrapped  in  tough  paper  with  directions  for 
aiDplication  printed  thereon.^ 

Clothing. — The  chief  function  of  clothing  is  to  assist  in  the  main- 
tenance of  an  equable  body  temperature.  Further,  there  are  military 
reasons  for  the  adoption  of  the  fabric,  color  and  style  of  clothes :  wearing 
quality  and  protection  not  only  against  the  elements  but  the  enemy  must 
be  considered.  In  modern  warfare  showy  uniforms,  such  as  worn  by  the 
British  "red-coats"  and  the  French  red-trousered  Zouaves  have  given  way 
to  colors  which  make  less  conspicuous  targets.  The  colors  now  preferred 
are  brown,  olive-drab,  khaki,  green-gray,  and  similar  shades  that  blend 
with  the  landscape.  It  is  also  now  customary  to  have  little  difference 
between  the  uniforms  of  officers  and  men.     The  great  loss  of  officers  in 

*  Drill  Eegulations  and  Service  Manual  for  Sanitary  Troops  U.  S.  A.,  1914, 
p.  143. 


1200  MILITARY  HYGIENE 

the  British  Army  in  the  present  war  was  due  partly  to  their  distinctive 
dress  and  conspicuous  station  in  front  of  the  command. 

The  British  and  French  cloth  for  uniforms  is  a  heavy,  feltlike  ma- 
terial, which  absorbs  rain  and  perspiration,  gathers  dirt,  and  when  driven 
into  the  body  in  shell  wounds  is  very  apt  to  give  rise  to  serious  infections. 

Allowances  are  usually  made  for  the  dress  of  native  troops.  For 
instance,  the  Cossacks  habitually  wear  their  sheepskin  coats ;  the  Filipino 
Constabulary  want  nothing  but  a  coat  and  hat;  the  Sikhs  wear  their 
turbans,  etc.  Other  reasons  such  as  climate  and  occupation  govern  the 
type  of  uniforms.  For  instance,  our  troops  in  Arctic  posts  are  supplied 
with  mackinaws,  fur  caps  and  gloves;  aviators  affect  a  tight-fitting, 
closely  woven  uniform,  with  cap  and  mask  designed  to  offer  but  little 
resistance  to  the  wind  and  to  prevent  the  radiation  of  body  heat. 

The  materials  used  for  clothing  for  military  purposes  are :  wool,  cot- 
ton, linen,  paper,  leather,  fur,  rubber,  etc. ;  also  such  mixtures  as  shoddy, 
merino,  etc. 

Of  these  substances,  wool  is  perhaps  the  most  valuable.  It  is  a  poor 
conductor  of  heat,  absorbs  water,  l)ut  gives  it  up  slowly ;  whereas,  cotton 
becomes  wet,  dries  quickly,  and  therefore  feels  damp  and  chilly  when 
moist.  Wool,  however,  has  the  disadvantage  of  shrinking  on  washing. 
Cotton  besides  being  cheap,  wears  well,  is  cool,  and  does  not  shrink. 
Merino,  a  mixture  of  cotton  and  wool,  is  much  used  for  underwear. 
Linen  conducts  heat  more  readily  than  cotton,  but  absorbs  moisture 
poorly;  furthermore,  it  is  more  expensive  than  cotton.  Paper  conserves 
warmth  and  was  used  by  the  Japanese  for  this  purpose.  .  A  paper  vest 
makes  an  excellent  protection  against  cold  winds,  and  a  newspaper  be- 
tween blankets  on  a  cold  night  helps  to  keep  the  body  snug  and  warm 
and  takes  the  place  of  extra  covering. 

The  usefulness  of  clothing  depends  not  alone  on  the  material,  but  on 
the  weave,  texture  and  color  of  the  fabric.  White  is  the  coolest  and 
black  the  warmest,  with  blue  a  close  second.  Olive-drab  is  somewhat 
warmer  than  khaki,  which  is  a  closely  woven,  hard  finished,  cotton  cloth. 

Water-proofing  may  be  accomplished  either  by  coating  the  cloth  with 
an  impervious  substance,  as  rubber,  or  by  impregnating  the  fibers  them- 
selves. The  former  is  completely  imper-^'ious,  the  latter  partially.  The 
fibers  may  be  waterproofed  by  spraying  the  cloth  with  a  solution  of 
varnish  or  similar  substance ;  it  may  be  done  in  the  field  by  means  of  an 
aluminum  acetate  solution.  Woolen  fabrics  may  be  treated  with  lanolin 
dissolved  in  benzene,  thus  replacing  the  fat  which  made  it  waterproof 
for  its  original  owner.  Waterproofed  fibers  are  intended  to  protect 
against  inclement  weather,  not  against  cold,  for  obviously  they  are  pervi- 
ous to  body  heat  and  partially  to  moisture.  On  the  other  hand,  rubber 
and  fur  retain  both  moisture  and  heat.  'I'lie  Jicw  infantry  poncho  is  of 
waterproof  olive  di'nl)  cotlon,  stiltstit  irtcd  for  llii'   roMiici-  licaxier  one  of 


EQUIPMENT  1201 

rubber  surfaced  cloth.  Slickers  for  mounted  troops  are  merely  longer 
ponchos  designed  to  cover  the  saddle  and  equipment. 

Leather  is  largely  confined  for  military  purposes  to  trappings,  belts, 
shoes,  etc.  For  men  who  handle  heavy  guns,  however,  leather  gloves  are 
furnished.  Fur  is  used  almost  exclusively  for  mittens  and  caps,  both  of 
which  may  be  wool  lined  and  are  designed  solely  for  service  at  cold  posts. 

The  total  weight  of  a  soldier's  uniform  varies  from  six  and  one-half 
to  twelve  pounds,  depending  upon  the  climate.  The  styles,  colors, 
weightS;  and  other  qualities  of  soldiers'  clothes  are  changing  continually. 

Headgear. — An  ideal  headdress  should  be  light  in  weight  and  color, 
well  ventilated,  flexible  enough  to  take  the  shape  of  the  head,  and  de- 
signed to  protect  both  the  neck  and  head  from  sun  and  cold;  further,  it 
should  shield  the  eyes;  be  comfortable,  and  not  readily  dislodged.  Our 
new  service  hat,  the  "Montana  Peak,"  is  perhaps  the  best  adapted  of  all  in 
use,  although  it  has  certain  disadvantages.  The  pith  helmet  has  been 
found  by  actual  experience  as  well  as  experiment  to  be  better  adapted  than 
any  other  style  of  headdress  for  tropical  use.  For  cold  posts  fur  and  can- 
vas caps  with  ear  flaps  are  issued  to  our  troops.  Pressed  steel  helmets 
have  been  supplied  some  of  the  troops  engaged  in  trench  fighting  in  the 
present  war.  These  are  designed  to  protect  the  head  against  shrapnel  and 
grenade  fragments.  Masks  designed  to  hold  chemicals  to  protect  against 
the  so-called  "gas  curtains,"  are  used  abroad,  in  order  to  neutralize 
chlorin  and  bromin  fumes. 

Coats. — Coats  are  designed  to  fit  fairly  snugly.  The  former  leaning 
toward  bizarre  designs  and  colors  is  giving  way  to  the  practical  ideas  of 
service,  utility  and  warmth.  Overcoats  no  longer  have  a  hood ;  mack- 
inaws  are  furnished  for  service  in  Alaskan  posts.  Ponchos  are  issued 
to  foot  soldiers,  the  idea  being  borrowed  from  Central  America,  where 
they  are  much  in  use.     Slickers  are  regularly  issued  to  mounted  troops. 

Leggings. — Leggings,  or  articles  serving  their  purpose,  are  of  many 
kinds  and  designs.  Some  armies,  as  the  German,  are  supplied  with  high- 
topped  boots  which  serve  both  as  shoes  and  leggings.  Leggings  or  gaiters 
may  be  of  leather,  duck  or  woolen  strips  arranged  so  as  to  protect  the 
entire  shin  or  only  the  lower  part.  The  United  States  Army  legging  con- 
sists of  heavy  canvas  with  reinforced  straight  edges,  and  have  a  three- 
point  lacing  on  the  side.  A  tape  on  the  inside  fastens  to  the  upper  of 
the  shoe  and  this  prevents  the  legging  rising  on  the  leg. 

Gloves. — Gloves  are  designed  and  issued  in  many  materials  and 
styles.  Mention  has  been  made  of  leather  ones  provided  handlers  of  big 
guns.  Leather  gauntlets  are  also  issued  to  the  cavalry.  Fur  mittens, 
wool  lined,  are  provided  for  northern  posts. 

Underwear. — From  the  standpoint  of  hygiene,  perhaps  the  most 
important  part  of  the  fighting  man's  dress  is  the  underwear.  It  is  sup- 
plied our  troops  in  merino,  light  and  heavy  wool.     An  apronlike  woolen 


1303 


MILITAEY  HYGIENE 


abdominal  protector  is  recommended  for  those  in  whom  exposure  to  cold 
causes  diarrheal  disturbances,  but  its  use  has  not  been  regarded  favorably 
by  our  troops.  Underdrawers  are  furnished  full  length  to  protect  the 
lower  legs  against  dirt.  Socks  issued  to  United  States  troops  are  made 
of  cotton,  half-cotton,  and  wool,  the  light  woolen  ones  being  preferred. 
The  English  have  estimated  the  life  of  socks  similar  to  our  light  wool  as 
being  sixty  to  seventy  road  miles. 

Shoes. — While  it  has  long  been  known  that  proper  footgear  is  indis- 
pensable to  an  army,  it  is  only  within  recent  years  that  the  subject  has 
been  studied  scientifically.  Disability  from  poorly  fitting  shoes  is  found 
both  in  military  and  civil  life,  and  forms  a  large  percentage  of  those  who 
fall  out  during  the  first  few  days  cf  maneuvers  or  the  march.     Some 

native  troops,  as,  for  exam- 
ple, African  native  sol- 
diery or  our  Filipino  con- 
stabulatory  may  wear  no 
shoes  at  all,  while,  on  the 
other  hand,  the  clumsy 
high-topped  boots  of  the 
Eussians  and  of  the  Ger- 
mans as  they  entered  the 
present  conflict  are  very 
heavy.  Our  men  probably 
have  better  shoes,  better 
shaped  and  better  fitted 
than  those  of  any  other  na- 
tion.   A  board  of  officers  of 


Fig.  170.— The  Nor- 
mal  Foot. 
A-B,  Meyer's  lines. 


Fig, 


B         B 

171.— Shape  of  U.  S. 

Military  Shoe. 
A-B,  Meyer's  line.  The 
dotted  line  shows  slight 
deviation  outward  so  as 
to  fit  the  average  foot 
accustomed  to  shoes. 

the  United  States  Army  in  1913  made  a  report  on  shoes  and  the  soldier's 
foot,  as  a  result  of  which  the  so-called  Munson  composite  last  was 
adopted.  The  recommendations  of  the  board  were :  ( 1 )  that  shoes  made 
over  the  Board  last  be  adopted;  (2)  careful  fitting,  personally  by  com- 
pany officers;  (3)  full  series  of  sizes  carried  by  posts;  (4)  frequent 
inspection  of  feet  by  commanding  and  medical  officers.  These  recom- 
mendations were  adopted  with  the  statement  that  "hereafter  any  undue 
amount  of  injury  and  disability  from  shoes  will  be  regarded  as  evidence 
of  inefficiency  on  the  part  of  the  officers  concerned  and  as  a  cause  for 
investigation." 

In  persons  who  wear  no  shoes,  the  axial  line  of  the  big  toe,  if  con- 
tinued, will  pass  through  the  center  of  the  heel  (Meyer's  line).  This 
fact  forms  the  basis  of  the  Munson  last.  A  foot  soldier's  pack  weighs 
about  40  pounds,  and  with  this  weight  his  feet  tend  to  flatten  and  spread 
in  both  dimensions.  In  fitting  then,  he  is  required  to  stand  and  support 
a  40-pound  weight  while  his  foot  measure  in  length  and  breadth  is  being 
taken  and  recorded.     Shoes  are  then  selected  from  the  ninety  sizes  re- 


SANITATION  OF  BABEACKS  AND  PERMANENT  CAMPS  1203 

quired  to  be  kept  in  all  posts.  The  fit  should  be  verified  by  making  sure 
that  there  is  a  free  space  in  front  of  the  toes  and  sufficient  width.  It  has 
been  found  that  shoes  a  trifle  loose  will  cause  little  inconvenience, 
whereas  those  that  are  tight  surely  lead  to  trouble.  A  figure-of-eight 
strap  passing  under  the  arch  above  the  heel  and  crossing  over  the  instep 
tends  to  prevent  chafing  of  loose  shoes  for  those  whose  foot  peculiarities 
require  them.  A  recruit's  foot,  fitted  in  the  manner  outlined  above,  will 
so  develop  as  a  result  of  military  life  that  another  fitting  and  size  may 
be  necessary  some  months  later,  after  which  the  foot  ceases  to  spread. 

Munson  recommends  the  following  method  of  breaking  shoes  in 
quickly:  Have  the  men  stand  in  water  for  a  few  minutes  so  that  the 
lower  part  of  the  shoes  become  wet  and  pliable ;  next  have  the  men  walk 
on  level  ground  until  the  shoes  dry  on  their  feet.  Afterwards,  the  shoes 
may  be  waterproofed  by  rubbing  with  neat's-foot  oil.  The  disadvantage 
of  thorough  waterproofing  is  that  it  prevents  ventilation,  and  the  re- 
tained warmth  and  perspiration  has  a  tendency  to  soften  and  macerate 
the  skin.  Hence,  it  is  usually  better  to  allow  the  feet  to  get  wet  occa- 
sionally. 

PHYSICAL  TRAINING 

Young  soldiers  and  young  recruits  unaccustomed  to  active  muscular, 
exercise  soon  tire  out.  The  exercises,  therefore,  should  be  simple  at  first 
with  gradually  increasing  severity.  All  nations  realize  that  on  the 
soldier's  endurance  may  depend  success  or  failure;  therefore,  soldiers  of 
all  countries  are  given  systematic  exercise  in  garrison  and  encouraged  in 
athletics  so  far  as  possible.  Manuals  are  issued  for  both  gymnasium  and 
outdoor  work.  For  our  soldiers,  advantage  is  usually  taken  of  the  ma- 
terial at  hand,  and  the  exercises  favored  are : 

1.  Setting-up  exercises,  largely  limb  and  body  movements. 

2.  Marching,  double  time  and  running. 

3.  Eifie  and  saber  exercises. 

4.  Climbing,  jumping  and  vaulting. 

5.  Gymnastic  contests. 

6.  Athletic  contests,  wrestling  and  boxing. 

7.  Swimming.    ' 

The  beneficial  effects  of  these  exercises  soon  manifest  themselves  in 
stronger  muscles  and  increased  endurance. 


SANITATION  OF  BARRACKS  AND  PERMANENT  CAMPS 

Sanitation  of  barracks  and  permanent  camps  deals  with  sites,  build- 
ings, ventilation,  lighting,  heating  and  many  other  factors  which  have 


1304  MILITARY  HYGIENE 

been  discussed  in  other  pages  of  this  book.  A  camp  or  permanent  garri- 
son is  a  small  compressed  city,  with  a  peculiar  population  constitution, 
consisting  mostly  of  young  adult  males  selected  on  account  of  health  and 
physical  fitness.  Hence,  a  permanent  army  post  should  have  an  excep- 
tional health  record.  The  main  factor  to  guard  against  is  overcrowding. 
The  principles  of  camp,  post  and  barrack  sanitation  are  the  same  as  for 
other  habitations. 

Permanent  garrisons  should  have  complete  water  and  scAverage  sys- 
tems, either  independent  or  connected  with  the  neighboring  city.  Gar- 
bage and  wastes  are  either  burned  or  disposed  of  by  the  city  authorities. 
Crude  coal  oil  is  used  more  and  more  for  burning  wastes,  as  well  as  for 
mosquito  and  vermin  destruction. 

Quarters  and  grounds  must  be  kept  clean  and  orderly  at  all  times. 
This  requires  military  policing.  Careful  watchfulness  must  be  kept  over 
the  guard  house,  kitchen,  mess  halls,  latrines,  storage  rooms,  basements 
and  other  places  to  keep  them  from  becoming  dirty  or  infested  with 
vermin. 

The  medical  officer  looks  after  the  sanitary  conditions  of  the  post. 
The  regulations  prescribe  bi-monthly  examination  for  venereal  diseases, 
and  special  reports  of  any  outbreak  of  disease  or  other  unusual  incident 
likely  to  affect  the  health  of  the  command.  If  an  epidemic  occurs  he 
must  notify  the  commanding  officer  in  writing  and  forward  one  copy  to 
the  Surgeon-General  and  another  to  the  department  surgeon.  Progress 
reports  of  the  epidemic  are  included  in  the  monthly  sanitary  report, 
which  is  made  out  in  duplicate.  The  original  copy,  signed  by  the  com- 
manding officer,  finally  rests  in  the  Surgeon-General's  office,  the  duplicate 
remaining  on  file  as  part  of  the  medical  history  of  the  post. 


SANITATION  OF  TRENCHES 

The  sanitation  of  trenches,  such  as  are  used  in  modern  warfare,  pre- 
sents unusual  difficulties.  Owing  to  the  extended  use  of  hand  grenades, 
trenches  are  dug  deep  enough  so  that  the  soldier's  head  is  several  feet 
below  the  surface.  Trenches  are  usually  one  to  two  meters  wide  and 
often  contain  dugouts  for  shelter,  protection  and  other  purposes.  Con- 
necting laterals  communicate  with  the  reserve  trenches  in  the  rear.  Or- 
dinarily one  man  per  square  meter  is  stationed  in  the  first  line  trench, 
which  is  increased  to  four  or  five  in  time  of  attack. 

In  low  wet  ground,  or  in  rainy  weather,  water  collects  and  must  be 
pumped  out  or  drained.  The  trenches  may  be  floored  or  lined  with  wood, 
cement,  or  other  available  material. 

Eats  are  a  particular  nuisance  in  trenches  used  for  any  length  of 
time;   for   their   suppression    see   page    274.      Flies    al)ounrl,    owing   to 


SANITATION  OF  TEENCHES  1205 

dead  bodies  in  "no  man's  land"  between  the  opposing  lines,  and  also 
from  horse  manure.  Flies  are  held  to  be  responsible  for  much  of  the 
gastro-intestinal  disorders  among  the  troops  in  the  present  conflict.  Lice 
and  other  vermin  may  infest  the  trenches. 

Latrines  are  placed  in  covered  recesses  or  in  dugouts  a  short  distance 
to  the  rear  of  the  trenches,  and  connected  by  a  narrow  passage.  Lime 
and  sulphate  of  iron  are  used  plentifully  to  cover  excreta,  the  latter  if 
it  is  to  be  used  as  fertilizer ;  it  is  better,  however,  systematically  to  col- 
lect, burn  or  bury  such  material.  All  forms  of  trench  trash  and  debris 
are  collected  in  sacks  and  carried  to  the  rear  frequently. 

Provisions  are  made  all  along  the  line  for  daily  baths  so  far  as  possi- 
ble, and  tubs,  improvised  showers  or  designated  streams  are  used  for  this 
purpose. 

Commands  are  relieved  from  trench  duty  as  frequently  as  exigencies 
permit,  but  despite  the  unfavorable  conditions  there  has  been  surpris- 
ingly little  sickness.  Epidemics  have  been  rare  and  mild.  An  unusual 
number  of  cases  of  psychoses  developed  in  the  first  part  of  the  trench 
war,  but  the  mentally  unfit  were  soon  weeded  out. 

Many  trenches,  especially  in  France,  are  dug  in  land  that  has  been 
intensively  cultivated  for  centuries,  hence  infections  such  as  tetanus  and 
the  gas  bacillus  (B.  WeJchii)  frequently  complicate  wounds. 

Water. — Drinking  water  for  the  soldier  needs  the  same  supervision 
and  purification  as  that  for  the  civilian.  (See  Chapter  on  Water.)  Per- 
manent camps  have  a  system  of  waterworks  corresponding  to  towns.  Sup- 
plies for  armies  on  the  march  and  temporary  encampments  sometimes 
present  unusual  difficulties. 

A  soldier  needs  at  least  three  quarts  daily  for  drinking  and  cooking, 
and  another  three  quarts  for  washing.  These  are  minimum  amounts. 
This  must  be  increased  by  one-third  or  one-half  in  the  tropics.  In  per- 
manent garrisons  at  least  thirty  gallons  per  capita  per  day  should  be 
provided. 

While  on  the  march  it  is  important  that  a  medical  officer,  well  in 
the  van,  makes  a  sanitary  survey  of  all  available  water  supplies,  which 
may  be  supplemented  by  a  few  simple  field  tests.  All  wells,  springs, 
streams,  etc.,  should  be  plainly  labeled  before  the  command  arrives. 
When  a  stream  is  reached  it  is  usually  crossed  for  tactical  reasons,  if  a 
halt  is  desired  at  that  point.  When  the  encampment  is  on  the  bank  of  a 
stream  it  should  at  once  be  policed  in  such  a  way  that  water  for  drinking 
and  cooking  is  drawn  farthest  up  stream,  that  for  bathing  and  lavmder- 
ing  farthest  dovni  stream,  while  animals  are  watered  between.  If  it  is 
desired  to  fill  canteens  it  is  best  to  provide  small  excavations  for  that 
purpose,  otherwise  the  water  will  soon  be  rendered  muddy,  making  it 
undesirable  for  those  farther  down  the  bank. 

Boiling. — The  supply  for  the  day  may  be  boiled  in  open  kettles  at 


1206  MILITAEY  HYGIENE 

night,  so  that  it  may  be  cool  by  morning.  Or  each  soldier  may  boil  his 
individual  supply  in  the  canteen.  Boiling  is  a  safe  and  satisfactory 
method  of  rendering  water  safe.  In  the  exigencies  of  military  service 
boiling  is  not  always  practical,  and  when  resorted  to  must  be  carefully 
supervised. 

The  Forbes-Waterhouse  Sterilizer  is  based  upon  the  heat  exchange 
principle.  Crude  oil  or  solid  fuel,  however,  is  necessary  to  supply  the 
heat.  Moreover,  the  outfit  when  packed  is  heavy  and  bulky  and  has  there- 
fore been  discontinued  in  our  army. 

Distillation. — Distillation  is  mostly  confined  to  marine  use. 

FiLTKATiON. — Filtration  is  often  necessary  to  clarify  a  water,  but 
except  under  unusually  favorable  circumstances  cannot  be  depended  upon 
under  military  conditions  to  render  a  water  safe.  The  British  and 
French  troops  both  use  water  carts  holding  one  hundred  gallons,  •  fur- 
nished with  a  Pasteur  filter.  The  filters  clog  readily,  break  often,  and  the 
arrangement  is  not  wholly  satisfactory.  The  Japanese  made  use  of  the 
Ishiji  filter  in  the  war  with  Eussia,  based  on  the  principle  of  mechanical 
filtration  (page  890).  It  consists  of  a  conical  canvas  reservoir  sup- 
ported from  a  tripod,  and  having  two  canvas  lugs  near  the  bottom  which, 
hold  charcoal  and  sponge.    Alum  is  used  as  the  coagulant. 

The  Darnall  filter  used  in  our  army  is  also  based  upon  the  principle 
of  mechanical  filtration.  It  consists  primarily  of  a  reservoir  and  a 
siphon,  the  immersed  end  of  which  is  armed  with  a  wire  cage  over  which 
Canton  flannel  is  wrapped  as  a  filtering  material.  The  siphon  is  cleansed 
with  boiling  water  and  primed  with  a  small  pump.  The  water  to  be  fil- 
tered is  first  treated  with  the  coagulant, — alum  and  sodium  carbonate 
in  the  ratio  of  one  pound  per  five  hundred  gallons.  The  bacterial  effi- 
ciency is  about  ninety  to  ninety-five  per  cent.  The  Darnall  filter  can 
filter  two  hundred  gallons  every  four  hours ;  it  weighs  fifty-two  pounds. 
It  should  not  be  depended  upon  to  do  more  than  clarify  the  water, 
which  may  then  be  purified  with  chlorinated  lime. 

Chemical  Disinfection. — ^The  best  chemical  with  which  to  purify 
water  ia  bleaching  powder — chlorinated  lime  (page  900).  A  very  muddy 
water  may  first  be  filtered.  The  manner  of  "chlorinating"  water  in  our 
army  is  by  the  use  of  the  Lyster  bag.  This  consists  of  a  waterproof 
canvas  bag  holding  forty  gallons,  with  five  faucets  near  the  bottom,  so 
that  entrained  sediment  will  not  be  drawn  off.  A  glass  ampule  holding 
one  gram  of  chlorinated  lime  is  broken  into  a  little  water  and  this  poured 
into  the  bag.  This  is  in  the  proportion  of  one  part  of  chlorinated  lime 
to  150,000  parts  of  water;  in  terms  of  available  chlorin,  one  part  to 
300,000 — otherwise  expressed  as  3.3  parts  per  million.  At  least  half  an 
hour  should  elapse  before  canteens  are  filled  from  the  faucets. 

The  British  in  the  presejit  campaign  are  using  a  100-gallcn  metal 
tank  on  two  wheels,  to   which   twenty-five   grams   of   hypochlorite   are 


SANITATION  OF  TRENCHES  1207 

added.  Water  is  collected  from  indicated  sources,  and  allowed  to  stand 
over  night  with  its  charge  of  bleach.  The  French  water  cart  is  made  up 
of  two  barrels  on  a  pushcart,  or  may  be  horse  drawn.  The  water  is  also 
disinfected  with  bleach.  In  addition  both  forces  •  analyze  the  water  of 
springs,  wells,  streams,  etc.,  which  are  then  labeled  as  potable  or  non- 
potable.  The  sanitary  analysis  consists  chiefly  of  determining  the 
chlorids  and  intestinal  bacteria.  The  United  States  water  wagon  holds 
two  hundred  and  twenty-five  gallons  and  has  a  pump  for  filling. 

For  water-borne  diseases  and  other  considerations  concerning  drink- 
ing water,  see  Section  VI. 

Disposal  of  Excreta. — For  the  prevention  of  typhoid  fever,  dysentery, 
hookworm  and  other  infections  it  is  of  prime  importance  that  the  urine 
and  feces  be  disposed  of  in  a  safe  and  satisfactory  manner.  Of  all  camp 
wastes  the  discharges  from  the  body  have  the  greatest  sanitary  signifi- 
cance. For  permanent  garrisons,  sewerage  systems  with  water  carriage 
are  possible  and  desirable.  For  temporary  encampment,  burial  or  burn- 
ing are  the  most  satisfactory  methods. 

Various  types  of  incinerators  for  this  purpose  have  been  designed, 
such  as  the  Lewis  and  Kitchen,  and  the  McCall  Incinerators,  but  they 
are  clumsy,  heavy,  and  unless  carefully  tended  prone  to  become  nuisances. 

The  best  method  is  to  burji  the  material  with  crude  coal  oil,  which 
is  simply  poured  into  the  pit  and  lighted.  In  firing,  some  straw  or  other 
light  combustible  stuff  should  first  be  thrown  in. 

Lateines. — The  best  design  is  the  Havard  latrine  box.  The  seats 
are  arranged  so  that  they  are  always  closed  save  when  in  use,  and  are 
in  pairs,  back  to  back.  The  box  should  be  lightproof  and  fly-tight,  and 
should  completely  cover  the  pit,  which  is  ten  feet  deep  by  six  feet  wide; 
the  length  depends  upon  the  number  of  seats.  The  pit  is  edged  with  a 
board  frame  on  which  the  latrine  box  rests.  It  is  preferable  to  dig  the 
pits  in  pairs,  so  that  the  latrine  box  can  be  in  use  while  one  of  them  is 
being  burnt  out.  The  pit  is  so  deep  that  the  board  frame  is  not  affected 
by  the  fire,  and  the  flame  is  hot  enough  to  consume  the  material  with 
little  or  no  odor.  After  the  burning,  lime  may  or  may  not  be  sprinkled 
into  the  pit,  depending  upon  circumstances. 

In  the  absence  of  oil,  and  especially  on  the  march,  the  "straddle  pit" 
is  used.  This  is  simply  a  narrow  deep  trench  which  should  be  covered 
and  marked  on  leaving. 

All  camps,  both  temporary  and  permanent,  must  be  policed  to  prevent 
nuisances.  Discipline  concerning  latrines  and  their  use  is  a  very  impor- 
tant factor  in  camp  sanitation  (see  also  Section  VII). 

Disposal  of  Garbage. — The  only  satisfactory  method  of  disposing  of 
garbage  under  camp  conditions  is  by  burning;  if  this  is  not  practical  it 
may  be  buried  and  well  covered.  No  other  method  should  be  coun- 
tenanced.    Expensive  crematories   are  unnecessary,  for   simple   devices 


1208  MILITARY  HYGIENE 

serve  every  purpose.  Each  mess  should  incinerate  its  own  garbage 
promptly.  Garbage  burns  more  readily  if  the  solids  are  separated  from 
the  liquid,  which  may  be  done  by  a  sieve-covered  can. 

The  rock  pile  crematories  are  the  best  garbage  incinerators  for  camps. 
They  are  all  based  upon  the  same  principle,  but  it  is  unusual  to  find  any 
two  quite  alike.  Essentially,  they  consist  of  a  pile  of  embers  for  cre- 
mating the  heavier  portions  of  the  garbage,  and  the  fire  is  placed  against 
a  pile  of  rocks  which,  when  hot,  volatilize  and  consume  the  liquid  por- 
tion. The  designs  vary  from  circular  as  shown  in  Figure  171,  to  horse- 
shoeshaped,  with  or  without  a  stone  bottom. 

In  the  circular  rock  pile  crematory  the  fire  is  built  in  one  quadrant, 
into  which  solid  wastes  are  thrown.  The  central  pile  of  rocks  helps  in 
creating  a  draft  and  also  offers  a  larger  surface  for  evaporating  liquids, 
which  are  thrown  into  neighboring  quadrants.     Garbage  will  burn  itself. 


Fig.  172. — A  Rock  Pile  Crematory. 

once  the  fire  is  well  started,  or  it  may  be  assisted  with  coal  oil  or  other 
inflammable  material.  Unconsumed  particles  together  with  the  ash 
should  be  scraped  up  and  burned  every  morning  by  the  kitchen  detail. 
When  fuel  is  scarce  and  stones  few,  probably  no  device  for  the 
destruction  of  garbage  and  refuse  is  more  readily  improvised  than  the 
Caldwell  or  English  crematory.  It  consists  of  a  trench  ten  feet  long  and 
one  foot  wide  and  about  fifteen  inches  deep  at  the  middle  and  thence 
gradually  shallowing  up  at  each  end  to  the  surface  level.  Over  the  deep 
part  a  barrel  is  placed  and  around  it  is  constructed  a  chimney  five  feet 
high,  of  clay,  earth  or  sod,  sprinkled  with  water  and  packed  tightly.  Two 
openings  at  the  bottom  are  provided  for  draft.  A  fire  is  made  in  the 
interior  and  the  barrel  burned  out,  after  which  there  remains  a  solid 
cone  of  earth.  Fuel  and  garbage  are  dropped  down  the  chimney.  Of  the 
two  openings  the  one  to  leeward  is  closed.  A  bed  of  tin  cans  is  a  fair 
substitute  for  a  grate  (see  also  Section  VIII). 

REFERENCES 

Havard,  Valery:     "Military  Hygiene."     Wm.  Wood  and  Co.,  1914. 

Keefer,  Frank  R. :  "Military  Hygiene  and  Sanitation."  W.  B.  Saun- 
ders Co.,  1914. 

Harrington,  Charles,  and  Richardson,  Mark  W. :  "Practical  Hygiene." 
Lea  and  Febiger,  1914. 


EEFEEENCES  1209 

Fauntleroy:  "Notes  on  Medico-Military  Aspects  of  the  European 
War."     Published  by  Bur.  of  Med.  and  Surg.,  TJ.  S.  N.,  1915. 

"Drill  Regulations  for  Sanitary  Troops."  War  Department,  United 
States  Army,  1914. 

"Tables  of  Organization,  United  States  Army."     1914. 

"Field  Service  Regulations,  United   States  Army."     1914. 

"Manual  for  the  Medical  Department,  United  States  Army."     1911. 

"Army  Regulations,   United   States  Army."     1913. 

Lynch,  W.  D. :  "Report  of  Military  Observers,  Russo-Japanese  War." 
Part  IV,  United  States  Army,  1908. 

Gatewood,  James  D. :  "Naval  Hygiene."  P.  Blakiston's  Son  &  Co., 
1909. 

The  United  States  Naval  Medical  Bulletin.  Pub.  by  Bureau  of  Med- 
icine and  Surgery,  United  States  Navy. 

The  Military  Surgeon.  Pub.  by  the  Association  of  Military  Sur- 
geons of  the  United  States,  Army  Medical  Museum,  Washington,  D.  C. 


INDEX 


Abatement  of  nuisances,   387 
Abattoir,  610 

condemned  room,  611 
retaining  room,   611 
tank  room,  611 
Abba,  771 
Abbott,  360,  730 
Abel,  118 
Abortion,  contagious,  572 

lead   poisoning,    1050 
Abortive   cases  in  poliomyelitis, 
Abrin,  415,  645 
Absolute   humidity,    691 
Absorption,   soil,   771 
Acanthocephala,  788 
Acapnia,   681 
Acarines,  206,  287 
Accelerated  reaction  in  vaccinia. 
Accidents,  blindness,  70 
industrial,  1046 
preventable,  1044 
typhoid  fever,  1047 
Acetaldehyd,   chart  insert,   1046 
Acetoarsenite  of  copper,  218 
Acetone,  210 
Acetyl-cholin,  531 
Acharde,    619 
Achorion  schonleinii,  1095 
Acid,  benzoic,  526 
boric,  526 
citric,  554 
hydrocyanic,     210,     215. 

Hydrocyanic  acid  gas 
orotic,  554 
pyrogallic,  409 
pyrolignic,  540 
Acid  waters,  832 
Acids,   as   germicides,   116L 

mineral,  in  air,  668 
Acidosis,  and  milk,  557 
Acland,  T.  D.,  22,  39 
Acquired  immunity,  394 
Acridin,  chart  insert,  1046 
Acrolein,  chart  insert,  1046 
Actinomycosis,  617 
Activated  sludge  tanks,  971 
Active  immunity,  395 
Adametz,   567 
Adams,   Ch.   Pr.,   1177 


304 


18 


See     also 


Adaptation,    mental,    349 
Addiment,  442 
Adenoids,   1094 
Adjustments,  mental,  349 
Administration,   nuisances,    387 
Adsorption  of  soil,  771 
Adulteration,    food,    523 

meats,   609 

milk,    568 
Aedes    ealopus.      See    Stegomyia    calo- 

pus 
Aeration,  of   sewage,  970 

of  water,  827,  853,  898 
Aerial  conveyance  of  yellow  fever,  241 
Aerial  infection,  719 
Aerogenic   infection,   tuberculosis,   141 
Aesophagustomum  apoistomum,  788 
Aesophagustomum  stephanustomum,  788 
African   tick   fever,   206 
Agaricus  campester,  646 
Age,  in  census,  990 

legal   record   of,    1000 

life,  expectancy  of,  1032 

life  tables,  1032,  1033 

mortality  statistics,  1020,  1025,  1029 
table,  1029 
in  N.  Y.,  1030 

recruiting,   1179 

school  children,  1079 
Agglutination,  cholera,  114,  454 

glanders,  312 

melitensis,  322 
Agglutinins,    454 

group,  457 

proagglutinoid  zone,  455 
Agglutinophore   group,    456 
Agkylostoma  duodenale,  788 
Agramonte,  A.,  201,  206,  236,  245 
Air,  661 

alveolar,  663 

amount,  function  of  CO2,  669 
per  hour,  751 
required  for  ventilation,  750 

bacteria  in,   716 

cleanliness   of,    758 

cold,   damp,   700 
effect  of,  688 

complemental,    749 

composition,   661 


1211 


1212 


INDEX 


Air,  composition,  ammonia,  667 

argon,  665 

carbon    tlioxid,    668 

hydrogen  peroxid,  667 

mineral   acids,   668 

nitrogen,   665 

oxygen,  663 

ozone,  665 
cool,   dry,   702 
cooling   method,    765 
currents,  velocity  of,  686 
dead-space,   750 
disinfection,    1166 
dust  in,   1065 
dwelling    house,    748 
factor  of  safety,  750 
fresh,  735 
furnace,  dry,  765 
and  health,  662 
humidity,  689 
infection,  719 
lead    poisoning,    1048 
movements  of,   685 
physical  changes  in,  740 
poisonous  gases,  721 
recirculation  of,  748 
reserve,   749 
residual,  .749 
respiration,   changes,   749 
respiratory  vitiation,  749 
respiratory  volume,  753 
schools,   1086 
of  sewers,  960 
soil,  771 

standards  of  purity,   753 
stationary,   749 
supplemental,   749 
temperature,  687 
thermal  circulation,  759 
tidal,   749 

vitiation   by   adult,    751 
warm,  dry,   701 

moist,  700 
washers,   for   cooling,    766 
washing,    method,    748 
See  also  Atmospheric  pressure;   Car- 
bon,    dioxid;      Humidity;      Ven- 
tilation 
Air-borne   diseases,   716 
measles,  175 
tuberculosis,   141 
Air-borne  infection,  719 

hospital       experiences,       176.         See 
Droplet  infection 
Air  ducts,   756,   758 
Air-lock,    685 
Aitken,  712,  715 
Albany,  typhoid  in,  88 


Albert,   Henry,   92,    164 
Albinism,   506 
Albuminoid  ammonia,  841 
Albuminoids,  520 
Albuminuria,  orthostatic,  509 
Alcohol,  in  army  canteen,  1 192 

at  conception,  340 

delirium  tremens,  338 

as  a  disinfectant,   1162 

and  epilepsy,  511 

ethyl,  210 

hallucinosis,  338 

heredity,   340,   510 

immunity,   407 

inebriates,  number  of,  474 

insanity,  338,  339 

as  an  insecticide,  210 

Korsakow's  disease,  338 

and   memory,    341 

mental   deficiency,   339,   340 

mental   diseases,   338 

methyl,  210 

milk,  fermentation  of,  509 

pneumonia,   190 

psychoses,  338,  341 

and  resistance,  407 

senility,  339 

sex  hygiene,  66 

venereal   diseases,   66 
Alcoholic  deterioration,  338 
Alcoholic  hallucinosis.     See  Alcohol 
Alcoholism,  hereditary.     See  Alcohol 
Aleurone,  of  rice,  649 
Alexin,  413,  440,  442 
Algae,  in  lakes,  827 

in  reservoirs,   827 

in  sewage,  962 

in  water,  805,  824,  827 
cause  of  odors,   823 
Algerian   relapsing   fever,    207,   293 
Alkalies,  in  milk,   568 
Alkaline  carbonates,  in  water,  891 
Alkaloids,  putrefactive,  528 
Allan,    124,   945 

Alleghany,  typhoid  epidemic,  943 
Allen,  K.,  979 
Allergic,  458 
Allspice,   545 
Altitude,  682 

Altona,  cholera  epidemic,  930 
Alum,  coagulant  for  water,  891 

to  remove  color  in  water,  829 

sewage  precipitation,   966 

water    purification.      See    Aluminium 
sulphate 
Aluminium  hydrate,  848 
Aluminium  sulphate,  coagulant  for  wa- 
ter, 891 


INDEX 


1213 


Aluminium      sulphate,      reaction      with 
lime,  907 

reaction  with  soda  ash,  907 

Avater  purification,  906,  908. 
Alveolar  air,  663 
Alveolar  ventilation,  750 
Alvine    discharges,   83 
Amanita  alba,   647 
Amanita  bulbosa,  647 
Amanita  citrina  Pers.,  646 
Amanita  mappa,  647 
Amanita  muscaria  (L.)  Pers.,  646 
Amanita  patherina  D.  C,  646 
Amanita  phalloides  Fr.,  646 
Amanita  rubicens,  648 
Amanita  toxin,  646 
Amanita  verna  Bull.,  646 
Amanita  verosa  Fr.,  646 
Amanita  virescens,  647 
Amaurosis,  69 

Amblyomma   americanus,    291 
Amboceptor,  412,  442 
Amebic   dysentery,   122 
Amidonapthalene,  843 
Amines,   530 
Amitosis,    490 
Ammonia,  in  air,  662,  667,  726 

albuminoid,  in  air,  668 
in   sewage,   959 
See  also  Water 

free,   in   sewage,  959 
See  also  Water 

industrial  poison,  chart  insert,  1046 

as  an  insecticide,  210 

refrigeration,  776 

in   smoke,    709 
Ammoniacal  vapors,  in  air,  726 
Amoss,  307,  464,  740 
Amyl  acetate,  chart  insert,  1046 
Amyl  alcohol,  chart  insert,  1046 
Amylase,  milk,  561 
Anaboena,  826 

Anabolism,  nitrogen  cycle,  773 
Anaphylaxis,  457 

Arthus  phenomenon,  460 

bacterial  proteins,  465 

chronic,    459 

eczema,  468 

eggs,  643 

endotoxins,  466 

examples  of,  458 

experimental,   458 

feeding,   462 

food  idiosyncrasies,  467 

hay   fever,   468 

local,  460 

maternal  transmission,  462 

other  conditions  explained  by,  468 


Anaphylaxis,  pneumonia,  190 

protein  foodstuifs,   517 

protein  metabolism,  465 

serum,  458 

serum  sickness,  462 

shock,  466 

specificity,  460 

tuberculosis,   466 

vaccination,   467 
Ancylostoma  duodenale,  126,  788 
Ancylostomiasis.    See  Hookworm  disease 
Andalusian  fowl,  486 
Anderson,  J.  F.,  22,  79,  145,  170,  173, 
175,    207,    289,    296,    306,    308, 
421,    428,    434,    464,    570,    574, 
1111,  1116 
Anderson,  W.  G.,  671 
Anderson  process,  909 
Andrejew,   461 

Andrews,  J.  B.,  1038,  1056,  1060 
Andrews,  V.  L.,   1022 
Anemia,  522,  523 
Anemia  Commission,   131 
Anemometer,   753 
Angelici,   742 
Angstrom  unit,    1119 
Anilin,   industrial   poison,    1065 

chart  insert,    1046 
Anilin  dyes,  and  foods,  525,  544 
Anilin  oil,  insecticide,  210 
Animal   antitoxins,   421 
Animal    foods,    553.      See    also    Eggs; 

Fish;  Meat;  Milk 
Animal  matter  in  soil,  770 
Animal  parasites,  in  soil,  786 

in  water,   947 
Animals,  dead,  disposal  of,  981 

diseases  from,  362 

fats   of,    607 

parasites  in,  609 

slaughter    of,    613 
Ankylostoma  duodenalis,  254,  788 
Annato,   525,   568 
Annette,  H.  E.,  546 
Anopheles  albimanus,  230 
Anopheles  albipes,  230 
Anopheles   argyrotarsus,   230 
Anopheles  costalis,  230 
Anopheles  maculipennis,  229 
Anopheles  mosquito,  228 

breeding  places,   244 

life  cycle,   221,   222 

recognition   of,   230 
Anopheles  nigerrinus,  246 
Anopheles  pseudopunetipennis,   230 
Anopheles   quadrimaculatus,   230 
Anopheles  sinensis,   230 
Anopholinae,  206,  229 


1214 


INDEX 


Ante-mortem  inspection,   615 
Anterior  poliomyelitis,  304 
Anthracosis,   713 

industries,    1066 

smoke,  711 
Anthrax,    315 

destruction    of,    1106 

flies,  248,  251,  252,  254 

hides,  1073 

disinfection   of,   317 

immunity,   316,   396 

in   meat,    617 

mode  of  transmission,   206,   316 

natural  immunity,   393,   394 

prevention,    316,    1073 

refrigeration,    533 

resistance,  315 

soil,   769,  778,  783 

symptomatic,  393 

wool  sorter's  pneumonia,   1067,   1073 
Antibiosis,  1102 
Antiformin,   1160 
Antigen,  446 

glanders,   313 
Antimeningitis  serum,   200 
Antimony,   chart   insert,    1046 
Antiseptics,   1099 
Antitoxic  immunity,  413 
Antitoxic  unit,  431 
Antitoxin,  action  of,  419 

animal,  421 

bacterial,   421 

botulism,  628 

concentration   of,    423 

diphtheria,   169,  431 

diphtheria  unit,  431 

dried,  424 

ferment,  421 

Gibson's  method,  423 

mode   of   action,   424 

nature    of,    419 

plant,   421 

preparation,  422 

preservation,   422 

refining,   423 

specificity,    420 

standardization,  431 

tetanus,  81,  430,  433 

tetanus  unit,  434 

See  also  Serum;  Tetanus 
Antitoxins,  418 

Anti-tuberculosis   societies,   153 
Aphthous  fever,  317 
Appert,  M.,  540,  541 
Appetite,  551 
Apples,  bleached  with  sulphur,  537 

dried,  536 

evaporated,  537 


Apples,  in  jelly,  539 

Appleyard,   672 

Aqua  chlorini,  ophthalmia  neonatorum. 

73 
Aquaphones,   795 
Aquasphere,   661 
Aqueous  vapor,  689 
Arachnida,  203 
Arachnolysin,   412 
Aragao,   260 

Arctomys  bobac,  265,  279 
Area,   U.   S.   registration,   1018 
Areola,  vaccination,  4,  8,  12,  13 
Argas  persicus,  206 
Argon,    665 

Argyrol,  ophthalmia  neonatorum,  73 
Aristotle,   789 

Arithmetical  method  of  estimating  pop- 
ulation,  992 
Armauer,  324 
Arms,  163,  312 
Army  Medical  School,   1186 
Arning,  324 
Arnold,   601,    1071 
Arnold  steam  sterilizer,  1123 
Aron,   652 
Aronson,    704 
Arrhenius,   424 

Arsenate  of  lime,  insecticide,   219,  220 
Arsenic,  in  furs,  1061 

industrial    diseases,    1061;    chart   in- 
sert, 1046 

insecticide,  218,  256 

poison,    1061 
for  rats,  276 

preservative,  549 

in  wall-paper,  1061 
Arsenic   pock,    1061 
Arsenical    dips,    288 
Arsenical  poisoning,   1061 
Arsenious  oxid,  insecticide,  219 
Arsenite  of   copper,   218 
Arsenite   of   lead,    insecticide,    219 
Arsenite  of  lime,  insecticide,  220 
Arseniureted    hydrogen,     chart    insert. 

1046 
Artesian   springs,   815 
Artesian  water,   797 

analysis,  874 
Artesian  Avells,  812 
Arthus  phenomenon,  460 
Asaprol,   1153 

Ascaris  lumbricoides,  787,  788,  947 
Ascaris  maritima,  788 
Ascaris  texana,   788 
Aschaffenberg,  G.,  341 
Aschenheim,   706 
Ascoli,   452 


INDEX 


1215 


Asepsis,  1100 
Aseptol,  1153 
Ash,  of  food,  520 

of  milk,  555,  593 
Ashburn,    206,    245 
Asher,    709 
Ashes,  981 

dumping  of,  986 

incineration,  982 

See  also  Eefuse 
Ashford,  128,  131 
Ashland  typhoid  epidemic,  940 
Asiatic  cholera.     See  Cholera 
Asiatic   relapsing  fever,   207,   293 
Asitia,  521 
Asopia  farinalis,  207 
Aspergillus  flavescens,  655 
Aspergillus  fumigatus,  655 
Aspiration,   758 
Aspirators,   718 
Association      for      Labor      Legislation, 

1038 
Associations,  tuberculosis,   153 
Asterionella,   826 
Asthma,  serum  therapy,  464 
Atavism,  488 
Ataxia,  hereditary,  513 
Atmosphere,  movements  of,   685 

vitiated,   407 

See  also  Air 
Atmospheric  pressure,  681 

altitude,  682 

diminished,  681 

increased,   683 

measurement  of,  685 

normal,    681 
Atoxyl,  258 

Atreptic   immunity,   391 
Atropin,   anaphylactic   shock,   171 

muscarin,   647 
Atwater,  519 
Atwood,  345 
Auer,  460 
Austerlitz,  736 
Australene,  210 
Authority,   epidemic   campaign,   369 

federal   government,    quarantine,   383 

morbidity  statistics,  1003,  1005 

sanitary,   975 
Autoclave,  1124 
Autohemolysins,   450 
Auto-intoxication,   lactic    acid    flora   in 
colon,  566 

pellagra,  655 

unbalanced    ration,    517 
Automatic  thermometers,  1129 
Autopsy,  causes  of  death,  1022 
Autovaccination,  22 


Auzinger,  602 
Avery,  189 

Avian  tuberculosis,  136 
Ayres,  L.  P.,   1097 
Azobacter,    776 

Babcock,  S.  M.,  554,  559,  561,  654 

Babcock   method,    593 

Babes,   46 

Babesia   bigemina,    206,   289 

Babesia  (janis,   206 

Bacillary  dysentery,   121 

Bacilluria,  typhoid,  110 

Bacillus : 

B.   abortus,   572 

B.  acidi  lactici,  566 

B.   acidi  lactici,   Hiippe,   621 

B.  aerogenes    capsulatus,     566,     714, 

784,   946 
B.  anthracis,  destruction  of,  1105 
in  flies,   254 

wool  sorter 's  disease,  1073 
B.  Bordet-Gengou,  186 
B.  botulinus,   620,   626,   627 
B.  bulgaricus,  566 
B.  catarrhalis,  194 
B.  cholerae.     See  Vibrio  cholerae 
B.  cholerae  suis,  531,  619 
B.  cloacae,  Jordan,  621 
B.  coli,  chlorinated  lime,  904 
diarrhea,  946 
in  eggs,  642 
isolation  of,  863 
in  meat,  626 
meningitis,  197 
milk,    souring   of,    566 
in  oysters,   637 
thermostable  products  of,  550 
ultraviolet  rays,  911 
in   water,    862 
B.  coli  anaerogenes,  Lemblee,  621 
B.  coli  communior,  Durham,  621 
B.  coli  communis,  Escherich,  621,  628 
B.  coli  mutabilis,  Massini,  621 
B.  comma,  113 
B.  cyanogenes,  568 
B.   denitrificans,    776 
B.   diphtheriae,  resistance,   165 
and  tetanus,   78 
avirulent   strains,   163 
See  also  Diphtheria 
B.  diphtheroid,  common  colds,  194 
B.   dysenteriae,   121 
B.  enteritidis,  diarrhea,  946 
in   flies,   254 
meat,  619,  621 
ptomains,    531 
rat  infection,  279 


1216 


INDEX 


Bacillus : 

B.  enteritides  "  A, "  Gartner,  619,  621 

B.  erythrogenes,  568 

B.    fecalis     alkaligenes,     Petruschky, 

621 
B.  fluorescens,   864 
B.  icteroides,  620 
B.  icteroides,  Sanarelli,  621 
B.  influenza,  192,  194,  197 
B.  lactis  acidi,  566 
B.  lactis  aerogenes,  Escherich,  621 
B.  lactis  morbi,  577 
B.  lactis  viscosis,   567 
B.  leprae,  324 
B.  mallei,  310,  315 
cultures,  pure,  312 
meningitis,  197 
See  also  Glanders 
B.  maydis,  655 
B.  mesentericus,  946 
B.  paracolon,  620 
B.  paratyphoid,  93,  253,  531,  620 
B.  paratyphoid  "A,"  619,  624 
B.  paratyphoid  "B,"  619,  624 
B.  paratyphosus  "  A, "  Schottmiiller, 

621 
B.  paratyphosus  "  B,  "  Schottmiiller, 

621 
B.  pestis,  281 
fleas,  207,  266 
meningitis,  197 
tetanus,   78 
B.  prodigiosus,    disinfectant    control, 
1103,   1110 
droplet  infection,  720 
ground  water,  811 
milk,   568 
sewer  air,  730 
in  soil,  771 
B.  proteus,  diarrhea,  946 
meat,   626,   628 
in  soil,  774 
water,  864 
B.  proteus  vulgaris,  Hauser,  621 
B.  pseudotuberculosis  rodentium,  620 
B.  psittacosis,  620 
B.  psittacosis,  Nocard,  621 
B.  pyocyaneous,  diarrhea,  945 
diphtheria,  165 
flies,  253 
meat,  626 

thread  method,  1110 
B.  radicicola,  776 
B.   scarlatinae,  179 
B.   solaniferum,  648 
B.  subtilis,  78,  774 
B.  suicholerae,  Smith,  621 
B.  suipcstifer,  619 


Bacillus : 

B.  suisepticiis,  619 
B.  tetanus,  75,  80 
B.  tuberculosis,  134 

avian,  136 

bovine,  135 

fish,  136 

human,  135 

in  milk,  572 

resistance,  150 

viability,  150 
B.  typhi  murium,  279,  620 
B.  typhi  murium,  Loeffier,  621 
B.  typhosus,  83 

on  blankets,  102 

in  blood,  89 

carbolic  coefficient,  1106,  1111 

in  carriers,  92,  110 

cross  agglutination,  456 

in  feces,  89 

in  flies,  254 

in  healthy  persons,  94 

in  ice,  949 

meningitis,  197 

in  milk,  98,  574,  590 

in  nature,  94 

plants,  101 

in  soil,  769 

in  streams,  802 

ultraviolet  rays  and,  911 

in  urine,  89 

viability  in  different  substances,  94 

in  water,  96,  864 

Widal  reaction,  93 

See  also  Typhoid  fever 
B.  typhosus,  Eberth,  621 
B.  typhus  exanthematicus,  207 
B.  welchii,    590.      See    also    B.    aero- 
genes capsulatus 
Bacillus  carriers,  401 
acute,  365 
cholera,  117 
chronic,   365 
diphtheria,   162 
dysentery,   123 
influenza,  193 
pneumococcic,   191 
temporary,  365 
typhoid,   92,   110 
See  also  Carriers 
Bacot,  253,  265,  266 
Bacteria,  in  aii",  716,  71& 
from  cesspools,  978 
destruction  in  sewage,  964 
disinfection,  1099 
dust,  713 
in  eggs,  642 
flies,  252 


INDEX 


1217 


Bacteria,  formaldehyd  gas,  1135 
ice,  manufactured,  951 

natural,  950 
in  meat  poisoning,  619 
methods  of  destruction,  1108 
in  milk,  569,  588 
kinds  of,  589 
number  of,  570 
sour,  566 
nitrifying,  843 
odors,  relation  to,  703 
pollution,  tests  for,  818 
proteolytic,  533 
in  rain  water,  800 
in  sewage,  952,  959 

percentage  removal,  972 
in  sewer  air,  729 
in  sewer  gas,  729 
in  soil,  769,  778 
thermal  death  point  of,  550 
in  vaccine  virus,  7 
in  water,  858 
Bacterial  antitoxins,  421 
Bacterial  eflficiency  of  sewage  disposal, 

972 
Bacterial  poisons,  fish,  635 
Bacterial  proteins,  465 
Bacterial  rat  viruses,  278 
Bacterial  vaccine,  397.     See  also  Vac- 
cines 
Bactericidal  property,  blood,  440 

milk,  571 
Bacteriological    examination     of     milk, 

588 
Bacteriological    examination    of    water, 
858 
bacteria,  kinds  of,  861 
number  of,  858 

method  of  determining,  860 
cholera,  864 
colon  bacillus,  862 

fermentation  test,  863 
isolation,  863 
sewage  streptococci,   853 
typhoid  bacillus,  96,  864 
Bacteriological  standards  of   milk,  558 
Bacteriolysins,  440 
Baggage,  quarantine,  380 
Baginscky,  Adolf,  1098 
Bags,  refuse,   982 
Bailey,  W.  B.,  1033 
Baillarger,  785 
Bainbridge,  620 
Bait,  rat  poison,  276 
Baker,  M.  N.,  265,  789 
Bakery,  ventilation,  755 
Balantidium  coli,  787 
Balantidium  minutum,  787 
40 


Balardini,  654 
Baldwin,  466,  548 
Ballast,  382 
Bailey,  94 

Baltimore,    diphtheria    in    school    chil- 
dren, 163 
Bandi,  282 
Bang,  157 
Bang  method,  157 
Banks,  62,  263,  280 
Barber,  281 

Barbiero  fever,  206,  260 
Bargilli,  324 
Barium,  256 
Barium  carbonate,  276 
Barker,  L.  F.,  359 
Barmeister,  260 
Barometers,  685 
Baron,  John,  39 
Barracks,  1203 

ventilation,  754 
Barreto,  236 
Bartel,  145 
Barthel,  Chr.,  604 
Basins,  sewage,  969 
Bass,  653 
Bates,  L.  W.,  1062 
Bateson,  483,  485.  486,  509,  515 
Bathing,  1195 
Bat's- wing  burner,   725 
Bauchhuber,  1050 
Baumert,  667 
Baummann,  530 
Beach,  Fletcher,  344 
Bealle,  910 
Beat  hand,  1072 
Beaume's   law,   503 
Beehamp,  561 
Bechhold,  1152 
Becker,  551 

Beekwith,  H.  L.,  310,  667 
Bedbugs,  299 

kala-azar,  206,  301 

leprosy,  301,  327 

plague,  266 

relapsing  fever,  206,  293,  301 

suppression  of,  300 

tuberculosis,   301 
Bed  linen,  disinfection,  1174 
Beebe,  164,  1175 
Beef,  dried,  536 

jerked,  536 

tapeworm,  207,  633 

See  also  Meat 
Beef  extracts,  606 
Beef  juice,  607 
Beers,  C.  W.,  361 
Beetle,  black,  301 


1218 


INDEX 


Behring,    76,    143,    145,    167,    172,   418, 

433,  1105,  1162 
Belascaris  mystax,   788 
Belfast,   typhoid  fever,   100 
Bellei  test,  milk,  603 
Bendick,  118 
Bendig,  59 

Bends.     See  Caisson  disease 
Benedict,   F.   G.,   668 
Benevot-de-Neveu  process,  579 
Bensaude,  619 
Benzaldehyd,  as  an  insecticide,  210 

in  rabic  virus,  42 
Benzene    (benzol),   1065 
Benzidin  test,  milk,   603 
Benzin,  bedbugs,  300 

industrial  poison,  chart  insert,  1046 

as  an  insecticide,  218 

lice,  297 
Benzoate    of    soda,    food    preservative, 

539,  543 
Benzoic  acid,  526,  539,  543 
Benzol     (benzene),    409;    chart    insert, 

1046,  1064 
Benzol  poisoning,  1064 
Bergenholtz,  304 
Bergey,  739 

Bergmann,  J.  F.,  529,  603 
Beriberi,  649 

diet,  517,  522 

prevention,  652 
Berkefeld  filter,  895 
Berlin,  sewage  farms,  967 

water  borne  typhoid  in,  97 
Bernard,  737,  750 
Bernouille,  29 
Berry,   214,   215 
Bert,  665,  683,  684,  737 
Bertarelli,   E.,  69,  330 
Besredka,   108 
Betanaphthol,  130 
Beu,  739 
Beyer,   236 
Beyerinck,  776 
Bezzola,  340 
Bichlorid  of  mercury,  disinfectant,  1147 

formula,  solution,  1164 

ophthalmia  neonatorum,  72 
Bier's  method,  401 
Biggs,  54,  62 
Bignami,  229 

Bilharzia  haematobia,  947 
Bilibid  prison,  hookworm  in,  132 
Biliousness,   521 
Bill,  J.  P.,  788,  793 
Bill  of  health,  377 
Billings,  John  S.,  739,  1033 
Bimetallic  thermometer,  688 


Binnie,  469 

Binot,  J.,  716 

Biological  equilibrium  in  sewage,  962 

Biological  transmission,  201 

Biometry,  492 

Bircher,  919 

Birdseye,  291 

Birth  certificates,  996 

Birth  rates,  99S 

crude,  998 

definition,  991 

error,  sources  of,  999 

factors   influencing,    1001 

illegitimate,     per      1,000     unmarried 
women,  998 

infant  mortality,  1001,  1031 

lead  poisoning,   1050 

legal  record  of,  1000 

legitimate,  per  1,000  married  women, 
999 

Massachusetts,   1023 

Michigan,  995 

mortality    rate,    influence    of,    1001, 
1027 

per  1,000  population,  998 

per     1,000     women     of     childbearing 
age,  998 

use  of,  999 

and  women,  number  of,  1001 

See  also  Birth  registration 
Birth   registration,    996 

authority,  996 

checks  upon,  999 

data,   source   of,   997 

model  bill  for,  996 

nature  of  information,  997 

responsibility  for,  997 

stillbirths,  997 

U.  S.   registration   area,   997 

value  of,  995,  997 

See  also  Birth  rates 
Birth    statistics,    995.      See    also    Birth 

registration 
Births,  registrar  for,  997 

U.  S.  registration  area,  997 

See  also  Vital  statistics 
Bisulphid    of    carbon,    insecticide,    216, 

217,  264 
Bitter  milk,  567 
Bitzke,   135 
Bixa  orellana,  525 
Black,  200 
Black  beetle,  301 
Black  Hole  of  Calcutta,  736 
Black  leg,  393 
Blackboards,  1085 
Blackwater  fever,  235 
Blaizat,  69 


INDEX 


1219 


Blanchard,  163,  326 

Blatta  germanica,  301 

Blatta   orientalis,   301 

Blattidae,  301 

Bleached  flour,  525 

Bleaching,  and  colored  water,   828 

Bleaching     powder.       See     Chlorinated 

lime 
Blind,  number  of,  474,  475 
Blindness,   preventable,   69 
Bliss,  547 
Blood,  bactericidal  property,  440 

immunity,  392 

stains,  453 

typhoid  bacilli  in,   89 
Blood    relationship     (Nuttal),    precipi- 
tins, 452 
Blood-sucking  parasites,  205 
Blood  tests,  452 
'  *  Blowers, ' '  ventilation,  762 
"Bob-veal,"   640 
Body,  dead,  1175.     See  Cadaver 
Body  heat,  697 
Body  lice,  297 
Boeck,    326 
Boehm,  648 
Bogliolo,  329 
Bohr,   666 
Boiled  milk,  586 
Boiled  water,  882 
Boiling,  disinfectant,   1122 
Boizenburg,  117 
Bokorny,  881 

Bolduan,  172,  469,  575,  1015 
Boletus  erythropus  Cke.,  646 
Boletus  felleus  Bull.,  646 
Boletus  luridus  Schaeff.,  646 
Boletus  satanus  Lenz,  646 
Bollinger,  641 
Bolton,  428 
Bones,  brittle,  509 
Boobyer,  955 
Books,  disinfection,  1174 
Boophilus  bovis,  289 
Boracic  acid.     See  Boric  acid. 
Borax,  255,  546 
Bordeaux  Mixture,  220 
Borden,  Gail,  579 

Bordet,  184,  438,  441,  442,  445,  469 
Bordet-Gengou  bacillus,  186 
Bordet-Gengou  phenomenon,  445 
Boric  acid,  526,-538,  546 

ophthalmia  neonatorum,  72 
Borrel,  429 

Boston,    diphtheria   in   school   children, 
163 

milk  borne   epidemics,   572 

milk  borne  typhoid  epidemic,  99 


Boston,  scarlet  fever  outbreak,  181 

septic  sore  throat  epidemic,  575 
Boston  school  desk,  1084 
"Bottle"   method,   pasteurization,   585 
Bottles,  for  water  samples,  822 
Botulism,  626 

effect  of  brine,  539 

prevention  of,  628 

source,  627 

symptoms,  627 
Botulismus  antitoxin,  628 
Bouley,  51 
Boussingault,   840 
Boux,  429 

Bovine  malaria,  288 
Bovine  tuberculosis,   135,   157,  572 
Bovine   vaccine   virus,   4 
Bowditch,  701,  785,  1081,  1090,  1098 
Bowley,  Arthur,  496,  1033 
Boyce,  637 
Boycott,  699 
Boylston,  3,  28 
Brachydactylism,  508 
Bradfort,  260 

Bramhall-Deane  sterilizer,  1124 
Brand  cancer  of  cattle,  504 
Brandeis,.  1042,  1043,  1075 
Brandt,    1056 
Brass,  chart  insert,  1046 
Braunia  jayensis,  788 
Bread,  fermentation  in,  551 
Breath,  poisons  in,  738 
Breathing,  regulation  of,  670.  See  also 

Eespiration 
Breaudat,  652 

Breeding    places    of    mosquitoes,    arti- 
ficial, 223 

natural,  225 
Breeding  rats,  268 
Bretonneau,  172 
Breweries,  CO,  in  air,  738 
Brieger,  426,  427,  528,  530,  640,  738 
Brigade,  1186 

Brighton,  diphtheria  in  school  children, 
163 

typhoid  in,   101 
Brill's  disease,  296 
Brinckerhoff,  25,  32,  280,  324,  328 
Brine,  preservative,  538 
Brion,  619 

British   thermal  unit,   763 
Broad  irrigation,  sewage,  966 
Broad  Street  cholera  outbreak,  116,  929 
Broggi,  1043 
Broiling,  of  foods,  552 
Bromin,  1161 
Bronfenbrenner,  57 
Bronze,  chart  insert,  1046 


1220 


INDEX 


Brown,  575,  590 

Brown-Sequard,  511,   738,  739 

Brownian  movement,  disinfection,  1107 

Bruce,  206,  257,  319 

Brack,   100 

Brues,  202,  203,  206,  250,  306,  308 

Briiner,  881 

Bruns,  80 

Bryant,  519 

Bubonic  plague,  280 

Buchanan,  George,   159 

Buchner,  413,  438,  439 

Buckwheat  poisoning,  655,  705 

Budd,   704 

Buffard,  260 

Buhach  insect  powder,  213 

Buildings,  rat-proof,  274 

Bulstrode,  638 

Bunsen,  705 

Burckhard,   13 

Burdon-Sanderson,  533 

Bureau  of  the  Census,  993 

Biirgers,  118 

Burial  permit,   1019 

Biirker,   681 

Burning,  disinfectant,  1121 

Butchers,  611 

Butler,  471 

Butler  typhoid  epidemic,  942 

Butter,  580 

formation  of,  556 

test  for  oleomargarine,  581 

typhoid  fever,  100 
Butter  fat,  556 

Babcock  composition,  555 

in  butter,  580 

standards  of,  557 

State  requirements,  558 
Buttermilk,  typhoid  fever,  100 
Buxton,  443,  620,  624 
Buyo   cheek  cancer,  504 
Byssinosis,  713,  1066 

Cabot,  Eichard  C,  44,  1021 
Cacchetto,  69 
Cadaver,  anthrax,  315 

disinfection,   1175 

embalming,   1175 
Cadaverin,  530 
Cadman,  699 
Cagnina,  324 
Cahan,  1059 

Caisson   disease,   681,  684 
Calabar   swelling,   206 
Calcium  borate,  255 
Calcium  carbonate,  in  water,  834 
Calcium  hypochlorite,  901.     See  Chlori- 
nated lime 


Calcium  oxid.    Bee  Lime 
Calcium  oxychlorid,  901 
Calcium  salts  of  milk,  556 
Calculi,  and  overeating,  521 

and  water,  916 
Caldwell   crematory,   1208 
Calkins,  25,  826 
Calmette,  46,   144 
Calomel  ointment,  syphilis,  58,  67 
Calorie,  518,  763 
Calvert,   H.   T.,  979 
Calves,  "bob-veal,"  640 
Camp,  choice  of,  1197 
diagram  of,  1196 
See  also  Military  hygiene 
Camp  sanitation,  1194 
Camp  sewage,  976 
Campaign,  against  insects,  204 
epidemic,    368 
tuberculosis,  158 
Campbell,  C,  350 
Camphophenique,  214 
Camphor,  insecticide,  210 
odor,  704 
spirits  of,  228 
Camus,  412 
"Can  ice,"  950 
Cancer,  and  fertility,  505 
heredity,  504 
occupational  disease,  1071 
Candles,  985 
Candling,  642 
Canine  babesiasis,  206 
Canned    foods,    540 
containers  for,  541 
use  of  gum  in,  542 
use  of  varnish  in,  542 
Cannon,  522 
Cans,  for  foods,  541 
for  garbage,  982 
for  refuse,  982 
Canteen,  1192 
Carbohydrate  foods,  520 
Carbolic  acid,  disinfectant,  1150 
disinfection  of  wells,  814 
feces,  1173 
formula,  1164 
industrial       poison,       chart       insert, 

1046 
insecticide,   210 
vaccine  virus,  7 
Carbolic   coefficient,   1111 
dilutions,  1114 
interpretation,  1116 
table  of  germicides,  1118 
technic,    1114 
Carbon,  refuse,  981 
in  smoke,  709 


INDEX 


1221 


Carbon  bisulphid,  in  air,  726 

bedbugs,  300 

industrial       poison,       chart       insert, 
1046 

insecticide,   210 

for  rats,  277 
Carbon  cycle,  777 
Carbon  dioxid,  688 

in  air,  amount,  662 

air  space,  relation  to,  755 

in  alveolar  air,  663,  669 

effects  of  increased,  737 

Fitz   tester,   680 

Haldane  apparatus,  673 

hygienic  significance,  671 

industrial       poison,       chart       insert, 
1046 

in  illuminating  gases,   726 

methods  of  determining,  672 

Petterson-Palmquist  apparatus,  675 

and  poisoning,  671 

respiration,  amount  in,  749 

samples,  collection  of,  672 

smoke,    708 

vitiation,  index  of,  671 

water,  hardness  of,  834 

Wolpert  tester,  679 
Carbon  monoxid,  in  air,  721 

in   illuminating  gases,   726 

industrial  poison,  chart  insert,  1046 

physiological  action,   721,   1063 

and  poisoning,  acute,  722 

rats,  destruction  of,  278 

smoke,   708 

tests  for,   723 
Carbon  tetrachlorid,  210,  217 
Carburetted  hydrogen,  in  air,  725 
Carcass.    8ee  Cadaver 
Carcinoma.     8ee  Cancer 
Cargo,  disinfection,  382 

on  plague  vessels,  375 
Carini,  23,  40 
Carlson,  666 
Carnelly,  671,  730 
Carpenter,  245,  766 
Carrasquillo,  327 
Carriers,   364 

acute,  365 

ameba,  125 

chronic,  365 

diphtheria,  164 

infantile  paralysis,  306 

malaria,   235 

meningitis,   198 

schools,  1092 

temporary,  365 

tetanus,  76 

typhoid,  92,   110 


Carriers,  water,  912 

&ee  also  Bacillus  carriers 
Carroll,   201,  206,  236 
Carrot  juice,  524 
Carter,  207,  235,  241,  243,  293 
Casein,  554,  566 
Casein  salts,  556 
Caseinogen,  556 
Castellani,  257,  260,  397 
Castle,  470,  483,  489,  500,  515 
Castor  bean,  415 
Castor   oil,   214 
Castration,  64 

Catabolism,  nitrogen  cycle,  773 
Catalase,   milk,   560 
Catalase  test,  milk,  602 
Cataract,  509 
Catch-basins,  819,  960 
Catchment  areas,  care  of,  819 

boards  of  jurisdiction,  975 
Cather,  68 
Catlin,  29,  165 
Cats,  bites  by,  42 

whooping  cough,  184 
Catsup,  sodium  benzoate  in,  545 
Cattani,  46,   252 
Cattle,  scabies,  212 

tick,  289 

dipping  for,  288 
Cattle  cars,  disinfection,  1180 
Cauterization,  -abic  wounds,  43 
Cavendish,   789 
Cedar  oil,  210 
Cell,  division,  490 

in  heredity,  490 

nutrition,  439 
Celli,  229,  231,  235,  251,  946 
Cellular  theory  of  immunity,  408 
Cement  water  pipes,  853 
Cemeteries,  soil  of,  779 
Census,  989 

arithmetical  method,  992 

data,  source  of,  990 

error,  sources  of,  990 

geometrical  method,  993 

information,  nature  of,  990 

population,  fluctuation  in,  991 
Centipede,  256 
Centrifugal  cream,  556 
Centrosome,  491 
Ceratophyllus  acutus,  263,  279 
Ceratophyllus  fasciatus,  263 
Ceratophyllus  fasciatus  Bosc,   262 
Cercariae,  207 
Cercomonas  hominis,  787 
Cercomonas  vaginalis,   787 
Cerebral  hemorrhage,  mental  deficiency, 
346 


1222 


INDEX 


Cerebrospinal  fever,   197 
carriers,   200 
death  rates,  173 
epidemiology,  197 
mental  deficiency,  346 
mode  of  transmission,  198 
prevention,   199 
protective  inoculations,   200 
and  schools,  closing  of,  200 
vaccines,   200 
Cerebrospinal  meningitis.     See  Cerebro- 
spinal fever 
Cernovodeanu,  1120 
Certificate  of  birth,  998 
Certificate  of  death,  1019 
Certified  milk,  563 
Cesspools,  977 
location  of,  955 
sludge,  978 
soil,  978 

pollution  of,  779 
wells,  978 
Cestoda,  788 
Chagas,  206 

Chair  car,  disinfection,  1170 
Chalicosis,  713,  1066 
Chalk,   school  use,  1085 
Chalmers,   229 
Chamberland,  45 
Chance,  law  of,  493 
Chancre,  55,  56,  57,  58 
soft.     See  Chancroid. 
Chancroid,  60,  67 

Ducrey's  streptobacillus,  60 
Channels  of  infection,   363,   366 
Chapin,    103,    161,    176,   326,   388,    720, 

946 
Chapman,  29 
Charrin,  454 
Chaussat,   260 
Chauveau,   143,  391 
Cheese,  typhoid  bacilli  in,  94,   100 
Chemical  analysis,  of  milk,  592 

of  water,   722 
Chemical  disinfectants,  1132 
acids,  1161 
alcohol,  1162 
antiformin,  1160 
asaprol,  1153 
aseptol,  1153 

bichlorid  of  mercury,  1147 
bromin,  1161 
carbolic  acid,  1150 
chlorin,   1144 
chlorinated  lime,  900 
coal-tar  creosote,  1149 
copper  sulphate,   1161 
creolin,  1153 


Chemical  disinfectants,  creosapol,   1153 

cresol,  1152 

cresolin,  1153 

cyllin,   1153 

disinfectol,    1153 

ferrous  sulphate,  1161 

formaldehyd,  1132,  1154 

formalin,  1136 

hydrocyanic  acid,  1132 

hydrocyanic  acid  gas,  1144 

iodin,   1161 

izal,    1153 

Labarraque's  solution,  1159 

lime,  1156 

lysol,  1153 

naphthalene,   1154 

naphthols,   1154 

phenol,  1151 

potassium  permanganate,  1135,  1155 

pulverizer,    1147 

sanatol,   1153 

soaps,    1162 

solutions,   use    of,    1147 

solutol,   1154 

solveol,    1154 

sulphonapthol,   1153 

sulphur   dioxid,   1132 

table  of  values,  1163 

"tar  camphor,"   1154 

zinc   chlorid,    1161 

See  also  Fumigation 
Chemical  disinfection,  sewage,  971 
Chemical    precipitation    tanks,    sewage, 

964 
Chemical  preservatives,  542 

of  milk,  568 

See  also  Preservatives 
Chemical  purification  of  water,  897 
Chemical  standards  of  milk,  558 
Chemotaxis,  436 
Chesbrough,  956 

Chest  measurements,  of  recruits,  1180 
Chicago,  typhoid,  water  borne,  97,  944 
Chick,   1106,   1107,  1112,  1116 
Chick-pea,  645 
Chickenpox,  309 

and   smallpox,   differential  diagnosis, 
309 
Chigos,  1183 
Child  labor,  1040 
Childbearing  age,  998 
Children,  disease,  causes  of,  1022 
gonorrhea  in,   59 
subnormal,  351 
tuberculosis  in,  156 
vulvovaginitis,  59 
Chimney  sweep's  cancer,  504 
Chisholm,  J.,  953 


INDEX 


1223 


Chiswell,  28 

Chittenden,  546 

Chlamydophrys  enchelys,  787 

Chloral,  171 

Chloretone,  210 

Chlorid  of  lime,  900,  971 

chai't  insert,  1046 
Chlorid   of   zinc,    1161 
Chlorides,  in  water,  834 
Chlorin,  "available,"  901 

fumigation,  1144 

industrial   poison,   chart  insert,   1046 

in  sewage,  959 

in  water.     See  Water 

water  purification,   905 
Chlorin  gas,   disinfectant,   1132 
Chlorinated  lime,  900 

American    standard,    1159 

composition  of,  900 

deodorant,  1158 

disinfectant,    1157 

excreta,   1159 

feces,  1171 

foi'mula,   1165 

germicide,    1157 
differential,  904 

hookworms,   130 

military  hygiene,  1206 

properties,    900 

solubility,   901 

water  purification,  901,  1159 

water  supplies,  method  of  dosing,  901 
Chlorobutanol,    vaccine    virus,    7 
Chloroform,  anaphylactic  shock,  171 

antitoxin,  422 

fleas,  264 

hookworms  and,   130 

insecticide,  210 

vaccine  virus,  7 
Chlorophyceae,   855,   857 
Chlorops   (musca)   leprae,  326 
Chlorops  vomitoria,  327 
Cholera,   112 

Altona  epidemic,  930 

bacillus  carriers,  117 

Broad  Street  pump  epidemic,  925 

contact  infection,  116- 

contributing  causes,  113 

diagnosis,  113 

flies,  117,  206,  252,  254 

Hamburg  epidemic,  929 

hog,   619 

immunity,  118 

incubation,    112 

London   epidemic,    825 

in   meat,    617 

in  milk,   117 

modes  of   transmission,   115 


Cholera,  in  oysters,  637 

personal  prophylaxis,  120 

Pettenkof er 's  theory,  113 

Pf eiffer  's  phenomenon,   441 

prevention,  120 

prophylactic  inoculations,   118 

quarantine,  119,  373 

soil,   785 

summary,  120 

vaccines,  118 

and  vegetables,   644 

water  borne,   115,  864 
Cholera  carriers,  methods  of  detecting, 

118 
Cholera  morbus,  112 
Cholera  nostras,  112 
Cholera  vibrio,  324 

in  soil,  769 

ultraviolet  rays,  911 
Cholesterin,  554 
Cholin,  531 

Chorea,  Huntington's,  hereditary  trans- 
mission of,  512 

school  children,  1096 
Chowning,    290 
Christenings,  999 
Christophers,  301 
Chromatin,  490 

Chromium,   chart   insert,   1046 
Chromosomes,  490 
Chronic  carrier,   365 
Chrysanthemum  carneum,  213 
Chrysanthemum  flowers,  210 
Chrysanthemum  roseum,  213 
Chrysops,   248 
Church,  798 
Churchill,  J.,  926 
Churchman,    503 
Cider,   in  jellies,   539 
Cimex  lectularius,  299 
Cincinnati,  typhoid  in,  99 
Cinnamon,   545 
Circumcision,  68 
Cisterns,   799 

disinfection,  1176 

screening,  against  mosquitoes,   226 

yellow  fever,   797 
Citellus   beecheyi,    265,    279 
Citrate,  sodium,  422 
Citronella,   210,   228 
Cities,       planning      of      refuse,       758, 
981 

of  registration  area,  1018 

water  supplies,  912 
table  of  volumes,  793 
Cladothrix  odorifera,   778 
Clarification  of  sewage,  964,  971 
1   Clark,  360,  835,  904,  906,  953 


1224 


INDEX 


Clark  degrees,  836 

Class,  495 

Classification,  of  meat,  612 

of  milk,  562 

of  soils,  768 

of  water,  790 
Clausen,  118 
Claviceps  purpurea,  645 
Clay,  in   soil,   768 
Clayton  furnace,  1144 
Cleanliness,  781 

of  air,  758 

disinfection,   1101 

hookworm,  132 

insect-borne  diseases,  205 

saliva,   161    . 

of  schools,  1088 
Cleft  palate,  499 
Clegg,   206,  324,  945 
Cleveland,  H.  B.,  979 
Clinics,  industrial  hygiene,   1039 
Clinocoris,  207 
Clinocoris  lectularis,  206 
Clinocoris  rotundatus,  206 
Cloak-rooms,   1088 
Clonorchis  endemicus,   207,   787 
Clonorchis   sinensis,   787 
Clostridium  pasteurianus,  776 
Clothes,  disinfection,  1174 
Clothing,  1199 
Clouston,  359,  511 
Clove  oil,  210 
Cloves,  545 
Clubfoot,   499 
Coaches,  disinfection,  1170 
Coagulants  of  sewage,  966 
Coal   dust,   1066 
Coal  gas,  723 
Coal  oil,  fleas,  264 

insecticide,  217 

for  lice,  297 

for  mosquitoes,  224 

test  for  pollution,   817 

See  also  Kerosene 
Coal-tar    disinfectants,    1149 
Coal-tar  dyes,  in  food,  525 
Cobalt,  256 
Cobbett,  144 
Cobbold,  206 

Cobwell   garbage   reduction,   985 
Cocculus  indicus,  295 
Cochin-China,   diarrhea,   127 
Coefficient,   of  insecticides,   210 

of  variability,  496 
Cohen,   70,  672,   708 
Cohen- Appleyard  method,   677 
Cohn,    426 
('ohnheim,   683 


Colt,  H.  L.,  563 

Cold,  bacteria,  effect  on,  949 

food,  preservation  of,  533 

See  also  Eefrigeration 
Cold  and  damp  air,  700 
Cold  and  damp  soil,  786 
Cold   storage,   533,   534 
Colds,   194 

causes,  194 

predisposing,  195 

drafts,   194,  196 

prevention,   195 
Cole,   188,   189,   1050 
Coleman,  443 
Colemanite,  255 
Coles-Finch,   798 
Colic,  lead  poisoning,  1050 
Collateral  benefits,  health  work,  133 
Collection,   of   garbage,   986 

of  rain  water,   799 
Colles'  law,  56,  503 
Colomba  livia,  489 
Colon  bacillus.     See  B.  coli 
Colon-typhoid   group,   621 
Colophony  resin,  214 
Color,  of  schoolroom  walls,  1080 

of  water,  1028 
Color-blindness,  hereditary,  506 

in  schools,  1093 

tests    for,    1093 
Colored   foods,  525 
Colored   milk,   568 
Columbella,  229 
Columbus,   55 

"Combined"  sewage  system,  957 
Comfort  zone,  698 
Comma  bacillus,  324.    See  also  CholerS' 

vibrio 
Commission,  milk,  564 
Commitment,  mental  defects,  338 
Common  colds.     See  Colds 
Communicable  diseases,  1004,  1072 

of  childhood,  1092 

definition,  367 

infection,  sources  of,  362 

in   schools,    1090 

See  also  Notifiable  diseases 
Complement,   in   anaphylaxis,   '"^63 

definition   of,   413,   442 

<leviation  of,  449 

fixation  of,  445 

hemolytic  system,  313 
glanders,  313,  314 
Complemental  air,  749 
Composition,  of  meats,  605 

of  milk,  554 

of  soil,  769 

of  water,  789 


INDEX 


1295 


Compulsory  vaccination,  25 

death  rates  compared  in,  26 

in   Germany,   33 
Condemned  meat,   612,   615 

diseases,  618 

disposal,  617 
Condemned  room,  611 
Condensed  milk,  579 
Condiments,   521 
Conduction,  697,  763 
Congenital  transmission,  501 
Conn,  100,  568,  638 
Conorhinus  megistus,  206,  260 
Conrad,  509 
Conradi,  104 
Consanguineous  marriages,  500 

retinitis  pigmentosa,  509 
Conscience  clause,  26 
Conseil,   175 
Constipation,  522 
Consumption.     See  Tuberculosis 
Contact  beds,  969 
Contact  infection,  364 

cholera,  116 

infantile  paralysis,  306 

tuberculosis,  146 

typhoid,  103 

in  Washington,  104 
' '  Contagious  "   vs.   "  infectious, ' '   366 
Contagious  abortion,  572 
Contagious  diseases,  366 

See  also  Notifiable  diseases 
Contagious    ophthalmia,    206 
Containers,  for  food,  541 
Contamination  of  wells,  812 
Continence,  65 
Control    of    outbreaks,    in    institutions, 

167 
Convection,  697,  763 
Cooking,  550 

methods  of,  552 

trichinous  meat,  631 

utensils  for,  551 
Cooks,  industrial  hygiene,  1043 
Cooling  of  rooms,  765 
Cooper-Hewitt  lamp,  910 
Cooperation,   in   epidemic   management, 

369 
Cooperative  sanitation,  975 
Copeman,  Moncton,  5,  6,  39 
Copper,  chart  insert,  1046 
Copper  acetoarsenite,  218 
Copper  arsenite,  218 
Copper  sulphate,   1161 

for  coloring  foods,  544 

in  water  purification,  910 
Copperas,  sewage  precipitation,  966 
Copula,  442 


Coquillett,  236 

Corn,  desiccators,  658 

pellagra  and,  656 
Cornell,  360,  1098 
Cornet,  142 

Cornet-Koch  theory,  141 
Cornutin,  645 

Corrected  death  rates,  1025 
Correns,  486 
Corrodor,   326 
Corrosive    sublimate,    1149.      See    also 

Bichlorid  of  mercury 
Corti,   1072 
Cost,  of  accidents,  industrial,  1038 

of  blindness,  preventable,  72 

of  diseases,  mental,  332 

of  typhoid,  84 
Cotton,  1200 

Cotton,  H.  A.,  334,  360,  572,  581 
Councilman,  25,   30,   198 
Course  of  vaccine  eruption,   12 
Cowpox,   1,  4 

vs.  smallpox,  24 
Cowsheds,  ventilation,  755 
Cow 's  milk,   and  woman 's  milk,  562 
Crab,  fresh  water,   207 
Craig,  229,  236,  245,  946 
Cranberries,  545 
Cream,  556 

typhoid  fever,  100 
Cream  line,  557 
Credo's  method,  72 
Creel,  101,  280,  1144 
Cremation,  of  sewage,  979 

See  Incineration. 
Cremation  plants,  984 
Crematory,   1208 
Crenothrix  kuehniana,  852 
Creolin,   1153 
Creosapol,  1153 
Creosote,  1149 
Creosote   oil,   210 
Cresols,  1152 

feces,  1173 

liquor  cresolis  compositus,  1152 

meta,  409 

trikresol,  1152 
Cresolin,  1153 
Crime,  prevention  of,  1023 
Criminals,  number  of,  474 
Cross-breeding,  500 
Cross-infections,   176,  720 
Croton  bug,   301 
Croup.     See  Diphtheria 
Croupous  pneumonia.     See  Lobar  pneu- 
monia 
Crowd  poisoning,  685 
Crowder,   743 


1226 


INDKX 


Crowding,   661 

Crude  morbidity  rates,  1014 

Crum,  F.  S.,  173 

Crustaceae,  in  sewage,  962 
in  water,   855 

Cruz,  O.,  242 

Ctenoeephalus  canis,  207,  263 

Ctenocephalus  felis,  263 

Cuenod,  69 

Culex  fasciatus,  236 

Culex  fatigans,  206,  221,  228,  245,  246 

Culex  pipicus,  230 

Culex  pipiens,  239,  245,  320 

Culex  pungens,  221,  222,  228 

Culex  quinque  fasciatus,  230 

Culex  sollicitans,  221 

Culieoides  brucei,  259 

Culicoides  grahamii,  259 

Culieoides  milnei,  259 

Cummings,  42,  46 

Cunningham,  62 

Curd,  milk,  562 

Currents,  air,  685 

Currie,  279,   324,  325,   708 

Curtains,   for   schools,   1086 

Curve  of  frequency,  494 

Cutting,  658 

Cyanophyceae,  855,  857 

Cyclops  coronatus,   207 

Cyclops  quadricornis,  947 

Cyllin,  1153 

Cyranase,  421 

Cystein,  324 

Cysticerci,  meat  inspection,  608 
pickling,  effect  of,  538 
thermal  death  point  of,  550 

Cysticercus  bovis,   617,   633 

Cysticercus  cellulosae,   273,  632 

Cysts,  meat,  617 

Cytase,  413,  442 

Cytolysins,   440 

Cytoplasm,  491 

Cytorrhyetes  variolae,  25 

Cytotoxins,  440,  445 

Czerny,   557 

Dairy-farms,  typhoid,  84 
Daltonism,  506.     See   also   Color-blind- 
ness 
Da  mien.  Father,  329 
Damp,   cold   air,   700 
Damp  soil,  786 
Dampness,  786 
Daniels,  229 
Danielson,    324 
Danysz  virus,  279 
Daphnia,   438 
Darling,    S.    T.,    230 


Darnall  filter,  1206 

D'Arsonval,   738 

Darwin,    Charles,    479,    482,    483,    515, 

767 
Darwin's  theory,  482 
Data,  births,   996 

diseases,  notifiable,  1012 
occupational,    1037 

hygiene,  industrial,  1037 

for  life  tables,  1032 

marriage   statistics,   994 

morbidity   rates,    1007,    1015 

mortality  statistics,  1019 
Davenport,    360,    477,    496,    501,    506, 

509,  513,  515 
Davies,   792 
Davinea   asiatica,   788 
Davinea  madagascariensis,  788 
Davis,  739 
Day,   165 

Dead   animals,    disposal   of,   981 
Deadrick,   236 
Dead-space,   air,    750 
Deaf,  number  of,  474,  475 
Deaf-mutism,  heredity,  505 
Dean,  162,  172,  325,  326 
Dearden,   1059 
Death,  cause  of,  1021 
errors  in,  1022 

from  sewer  gas,  731 

See    also    Death    rates    and    Death 
registration 
Death  certificate,  996,  1019 
Death   rates,   1024 

and  birth  rate,  1027 

central,   1024 

in   certain  countries,   1028 

computation,  1024 

corrected,    1025 

crude,  998,   1024 

factors   affecting,   1026 

hospitals   and,   1026 

institutions  and,   1026 

marital   status,    1028 

migration,    1027 

non-residents,   1026 

registration  area,  173 

sex,  1025 

for  short  periods,  1024 

specific,    1025 

standardized,  1025 

See  also  Infant  mortality;  Mortality 
rates 
Death  registration,  1017.   See  also  Mor- 
tality statistics;  Registration 
Deaths.     See   Vital   statistics 
De  Barros,  236 
De  Chaumont,  671,  704,  752 


INDEX 


1227 


Decomposition,  fermentative,  527 

of  foods,  526 

influence  of  syrups  on,  539 

of   milk,   565 

putrefactive,  527 

of   sewage,   959 
De  Crocq,  1071 
Defectives,  education  of,  356 

Indiana  law,  473 

and  isolation,  500 

number  of,  ;-532 

preventive   measures,   350 

propagation   of,  472 

school  children,   1097 

statistics   of,   474 

stigmata  of,  471 

See  also  Mental  deficiency 
Defects,  transmission  of,  499 
Definitive  host,  201 
Defoe,  385 
De  Frise,   899 
Degenerate  families,  476 
Degeneration,   stigmata   of,   471 
"Degging,"  1070 
De  Graef,  582 
Degrees  of  hardness,   834 
Dehaan,    652 
De   Jong,   582 
De  la  Condamine,  29 
Delepine,  Sheridan,  574 
Delinquents,  475 
Delirium  tremens,  338 
Deniarquay,   206 
Dembo,  614 

Dementia  precox,  339,  1180 
Demography,  989 
Dengue,   244 

mosquitoes,  206,  245 
Denier,  652 
Denitrification,  776 
Dennis,  723 
De  Nobele,  619 
Dental  clinics,  1094 
Dentist,  for  schools,  1094 
Denys,  429 
Deodorant,  1100 
Deodorizers,  schools,  1088 
Dependent,  number  of,  474 
Dermacentor  andersoni,  206 
Dermacentor  marginatus,  291 
Dermacentor  occidentalis,  290 
Dermacentor  variabilis,  291 
Dermacentor  venustus,  290 
De  Sandro,  405 
De  Schweinitz,  1072 
Desiccated  milk,  579 
Desiccation    of    foods,    536.      See    also 
Dried  foods 


Desiccators,  corn,  658 
Desks,  Boston  school,  1084 

Heusinger  's,  1083 

for  schools,  1082 
Desmon,  412,  442 
Desquamation,  measles,   175 

scarlet  fever,  180 
Detention,  period  of,  quarantine,  372 
Determiner,   in  heredity,  486,  488,   490 
Detritus  tanks,   964 
Deviation,  of  complement,  449 

in  heredity,  495 
De  Vries,  482,  483,  484,  486,  565 
Dew-point,  691,   696 
Deycke,   330 
Dhobie  itch,   1183 
Diabetes,  394 
Diabetes  mellitus,  509 
Diagnosis,   of   chicken   pox,   309 

of  cholera,   113 

differential,  309 

of  glanders,  311 

of  lead  poisoning,  1049 

percentage    correct,    1022 

of  rabies,  52 

of   smallpox,    309 

of  tuberculosis,  155 
Dagnostic  errors  in  mortality  statistics, 

1021 
Diamines,  531 
Diaphanometers,  831 
Diarrhea,  infantile,  and  flies,  254 
and  milk,  577 
water-borne,  945 
Diastase,  milk,   561 
Diatheses,   521 
Diatoms,  826,  855,  857 
Diazoraethane,  chart  insert,  1046 
Dibothriocephalus  cordatus,  788 
Dibothriocephalus  latus,  207,  635,   788 
Dibothriocephalus  parvus,   788 
Dichloromethane,  295,  297 
Dickson,   398 

Dicrocoelium  lanceatum,   787 
Dieudonne's  medium,  114 
Diet,  beriberi,  649 

diseases  and,  516,  522 

fuel  value  of,  518 

pellagra,  656 

salts  in,  523 

unbalanced,  522 

water,   912 
Digestion,  of  garbage,  982 
Digestion   tanks,   964,  966 
Digestors,  garbage,  985 

refuse,  985 
Dilution,   disinfection,   1101,   1107 
Dimethyl  sulphate,  chart  insert,  1046 


1228 


INDEX 


Dinitrobenzol,  chart  insert,  1046 
Dinobryon,  858 
Dioetophyme  renale,  788 
Diodon,  635 
Diphtheria,   159 

bacillus  carriers,   162 
cure  of  carriers,  164 
death   rates,    173 
epidemics,   control   of,   166 
historical  note,    172 
immunity,  165 
in   institutions,   166 
milk-borne,  162,  575 
modes  of  transmission,  160 
morbidity  rates,  1008,  1011 
mortality  rates,  1008 
outbreaks,   159 

control  of,  166 
personal  prophylaxis,   169 
postdiphtheritic  paralysis,  169,  421 
prevention,    166 
references,   171 
serum   sickness,    170 
susceptibility,  166 
value   of   reporting,    1014 
virulent  and   avirulent,   168 
virus,  resistance  of,   165 
See  also  Antitoxin 
Diphtheria      antitoxin,      prophylactic 

use,    169 
standardization,  431 
Diphtheroid  bacilli,  194 
Diplocpccus  intracellularis  meningitidis 

197 
Diplogonoporus  brauni,  788 
Diplogonoporus  grandis,   788 
Dip,  arsenical,  288 
lime-sulphur,   212 
Dipping,    for   ticks,   288 
Diptera,   247,   261 
Dipylidium  caninum,  263,  788 
Direct  system  of  heating,  765 
Dirt,  780.     See  also  Soil 
Dirt  test,  milk,  568 
Discharge   certificates,   hospitals,   1015 
Discontinuous   evolution,   483 
Diseased  meat,   615 
Diseases,   from   animals,   lower,   362 
and   diet,   522 
communicable,  367,  1004 
endemic,    202,    367 
epidemic,   367 
flies   and,   254 

hereditary   transmission,   498 
in  ice,   952 
insect  borne,  201 

table,   206 
of   meat,    618 


Diseases,   milk-borne,   571 
mosquitoes  and,  228 
notifiable,  1004 
pandemic,   367 
prevalence  of,  1001,  1017 
prosodemic,   367 
quarantinable,   372 
and  schools,  exclusion  from,   1092 
of   skin,  school  children,   1095 
and  soil,   778,  782 
of  soldiers,  1182 
swimming   pools    and,    948 
tick  borne,   288 
venereal,  53 
and  water,  915,  923 
See     also     Communicable     diseases; 
Morbidity   rates;    Notifiable   dis- 
eases ;     Occupational    diseases 
Disinfectant  standardization,  1109 
"drop"  method,  1111 
Garnet  method,   1111 
Hygienic  Laboratory  method,  1112 
Lancet  Commission  method,   1112 
physical-chemical  methods,   1111 
Eideal-Walker   method,    1111 
Sternberg's  method,  1110 
thread  method,  1110 
See  Carbolic  coefficient 
Disinfectants,  acids,  1161 
alcohol,  1162 
bacteria,   methods  of   destruction  of, 

1108 
carbolic  acid,  1150 
coal-tar   products,   1149 
disinfectol,   1153 
formulae,    1164 
gaseous,  1132 

hydrocyanic  acid  gas,   1144 
the  ideal,   1104 
liquid,   1125,   1146 
lysol,  1153 

method  of  action,  1108 
oxygen,  1146 
ozone,  666,   1146 
phenol,  1151 
soaps,  1162 

table  of  values,  1118,  1163 
temperature,  1106 

See  also  Bichlorid  of  mercury; 
Chemical  disinfectants;  Cresols; 
Chlorin;  Formaldehyd;  Formu- 
lae; Fumigation;  Physical  dis- 
infectants; Sulphur- dioxid  fumi- 
gation 
Disinfection,  1099 
of  air,  1166 

of  albuminous  matter,  1105 
amount  necessary,   1103 


INDEX 


1229 


Disinfection,  antibiosis  and,  1102 
antiseptics,  1099 

asepsis,  1100 

of  ballast,  382 

of  bed  and  body  linen,  1122,  1174 

bedside,  1103 

of  books,  1174 

of  cadavers,  1175 

of  cargoes,  387 

cesspool  sludge,  979 

chemical  agents  of,  1132 

cisterns,  1176 

cleanliness,  1101 

control  of,  1103 

deodorizing  action,  1100 

by   dilution,   1101,   1107 

in  diphtheria,  169 

by  dryness,  1101 

by  emulsions,   1107 

in  epidemics,  1102 

of  excreta,  1159 

of  feces,  1105,  1171 

of  fomites,  1104 

by  fumigation,  1100 

of  garbage,  1121 

gaseous,  1132 

germicide,    choice   of,    1108 

of  glassware,   1121 

of  hides,  317,  1073 

of  horse  hair,  317 

liquid,  1146 

of  merchandise,  1131 

methods,  1166 

municipal,  1131 

by  nature's  agencies,  1101 

of  oyster  beds,  972 

by  penetration,  1105 

physical  agents  of,  1119 

railroad  cars,   1169 

reaction  necessary,  1108 

of  refuse,  1121 

of  rooms,   1166 

routine,   1103 

of  sewage,  971 

of  ships,  379,  878 

in  smallpox,  36 

by  solutions,  1107 

of  sputum,  1105,  1173 

of  stables,  1168 

by  sunlight,   1101 

symbiosis  and,   1102 

table  of  antiseptic  values,  1163 

terminal,   1104 

of  thermometers,  1176 

time,  value  of,  401,   1106 

and  place  for,  1102 
of  vessels,  379 
of  watering  troughs,   1169 


Disinfection,  of  wells,  814,  1176 

See  also  Carbolic  coefficient;  Chemi- 
cal disinfectants;  Disinfectants; 
Feces  disinfection;  rormaldehyd 
fumigation;  Sulphur  dioxid  fu- 
migation 
Disinfectors,  qualifications  of,  1103 
Dispensaries,  mental,  354 

tuberculosis,   153 
Distilled  water,   882 
District  sewers,  957 
Diver's  palsy,   684 
Division  of  infantry,   1186 
Divorce,  994 
Dixon,   832 
Doane,  574 

Doane-Buckley  test,  milk,  591 
Dochez,  188,  189 
Dock,   10,   11,  917 
Doerr,  206,  261,  459 
Doflein,  260 

Dogs,  diseases  of,  transmissible  to  man, 
44 
fleas,  207 
lice,  207 

rabies,    diagnosis,    52 
muzzling   for,   43 
quarantining  for,  43 
tapeworm,  207 
whooping  cough,   184 
Domesticated    animals,    diseases    from, 

362 
Dominance,  hereditary,  485 
Don,  J.,  953 
Donitz,  118 
Donovan,  301 
Doran,   580 
Derange,  952 
Dornbleuth,  20 
Dorr,   122 

Double  water  supplies,  796 
Douglas,  608,  670,  750 
Dourine,   260 

Dracunculus  medinensis,  207,  788,  947 
Drafts,  196 

common  colds,  194 
velocity  of  air,  686 
Drainage,  for  mosquitoes,  224 
Drainage  area,  819 
Drainage  canal,  Chicago,  803 
Drains,  filter  beds,  968 

storm,   957 
Draschfeld,   106 
Dressier,  P.  B.,  1098 
Dried  antitoxin,  424 
Dried  beef,  536 
Dried  eggs,  537,  643 
Dried  fruits,  536 


1230 


INDEX 


Dried  meat,  536 

Dried  milk,  537 

"Drop"  method,  disinfectants,  1111 

Droplet  infection,   142,   719,   720.     See 

also  Air-borne  infection 
Drug  addictions,  342 
Drugs,  excreted  in  milk,  562 
Drunkards,  340 
Dry  climate,  691 
Dry  earth,  feces  disposal,  1173 

sewage  disposal,  956 
Dry  heat,  as  disinfectant,  1121 
Dry,  heated  air,  763 
Dry  points,  vaccination,  6 
Dry  vaccine,  5 
Dry-wall  sterilizer,  1121 
Dry,  warm  air,  701 
effects  of,  763 
Drying,  as  disinfectant,  1101 

of  foods,  536 
Dublin,  Louis  I.,  1029 
Ducrey's  streptobaeillus,  60 
Ducts,  air,  756 

ventilating,  758 
Dugdale,  476 
Dumb,  number  of,  475 
Dumps,  986 
Dunbar,  979 
Dunham,  620 
Dunham's  solution,  114 
Dupetit,  776 

Dupony's  method,  milk,  601 
Duprey,  945 
Durgin,  S.  H.,  1089 
Durham,  454,  619 
Dust,  712 

in  air,  of  factories,  1065 

anthracosis,   1066,   1071 

bacteria  in,    716 

byssinosis,  1067 

chalicosis,  1067 

coal,   1066 

coal  mining,  1070 

and  disease,   713 

"hecklers,"  1068 

hygienic  significance,  1066 

industrial  prevalence,   1066 

infantile  paralysis,  308 

the  konoscope,  715 

lead  poisoning,  1048 

Malta  fever,  320 

methods  of  examining,  715 

and  odors,  703 

physiological  effect,  713 

pneumonokoniosis,  1066 

prevention  of,  714,   1067 

siderosis,   1066 

source,  712 


Dust,   stone,   1066 

in  trades,   1065 

textile  industries,   1068 

and   tuberculosis,    141 

and  typhoid,  102 

ventilation,  1067 

wood,   1070 
Dutch  process,  white  lead,   1051 
Dutton,  206,  256,  257,  260,  294 
Duval,  324 

Dwarf  tapeworm,   207 
Dwellings,  near  privies,  976 
Dyer,  330 
Dyes,  anilin,  525 

coal  tar,  525 

mineral,  525 

vegetable,  525 
Dypilidium  caninum,  207 
Dysentery,   121 

amebic,  121 

baeillary,  121 

carriers,  125 

classification,  121 

emetin,  124 

flies,  206,  252,  254 

immunity,   123 

milk,  577 

mode  of  transmission,  122 

prophylaxis,  124 

and  rats,  273 

resistance,  123 

symptomatic,    121 

and  vegetables,  644 

water-borne,  944 
Dyson,  610 

Ears,  of  school  children,  1093 
Earth,  780 

dry,  for   sewage,  956 
Earthenware,  1052 
East  African  relapsing  fever,  293 
Eastman,  1037 
Eastwood,  139 
Ebstein,  549 
Ecdysis,  128 
Echeherria,  511 
Echinococcus  disease,  633 
Echinococcus  granulosus,  207 
Echinostoma  iloranum,  787 
Echinostoma  malayanum,  787 
Economic   factors  in  insanity,   352 
Economic  importance  of  rats,  273 
Ectoparasites,   203 
Eczema,  468,  522 
Eczema  contagiosa,  317 
Eddy,   979 
Edgar,  73,  74 
Edlemann,  609 


INDEX 


1231 


Edsall,    1049,    1050,    1062 
Education,  defectives,  356 

in  epidemic  campaigns,  371 

hookworm  prophylaxis,  132 

industrial  hygiene,  1039 

in  mental  diseases,  351 

in  sex  hygiene,  63 

subnormal  children,  351 

tuberculosis,  154 
Edwards,  1111,  1116 
Edwards  family,  478 
Eggs,  641 

anaphylaxis,  643 

bacteria  in,  643 

B.  coli  in,  642 

candling,  642 

classification,  642 

composition,  641 

dried,  537,  673 

frozen,  643 

infection  in,  643 

kinds  of,  641 
Egyptian  or  roof   rat,   268,   270 
Ehrenberg,  713 

Ehrlich,   172,   391,   401,   408,   409,   411, 
412,  413,  415,  417,  419,  424,  425, 
427,  428,  438,  442,  443,  456,  463, 
469,  533,  1152 
Ehrlich 's  side  chain  theory,  408 
Eichholz,  W.,  171 
Eichorn,    314,    609 
Eijkman,  650 
Eimeria  hominis,  787 
Ekenberg  process,  579 
Elberson,  575 
Elderton,  496 
Eldridge,  945 

Electric  incandescent  light,  725 
Electric  heating,  765 
Electricity,  707 

disinfectant,  1121 

water  purification,  910 
Ellison 's  bricks,  760 
Elmassian,  260 
Elser,  198 
Eisner,  A.,  979 
Elster,  708 
Elwyn,  epilepsy,  511 
Embalming,  476 
Emergency  ration,  1193 
Emergency  slaughter,  613 
Emerisch,  881 
Emery,   400,   404,   407,    436,   451,    452, 

454,  469 
Emetin,  124 

Emigration,  991.    See  also  Vital  statis- 
tics 
Emmerich,  113,  165 


Emotions,  mental  hygiene,  351 
Empusa  muscae,  249 
Emscher  sewage  tank,  966 
Emulsion,  kerosene,   218,   220 
Encephalitis,  1049 
Endemic,  definition  of,  367 
Endemic   diseases,  types,   202,   367 
Endemic  foci,  of  plague,  283 
Endemic  goiter,  916 
Endogenous  poisons,  342 
Endoparasites,  203 
Endo  's  medium,  in  diagnosis  of  typhoid 

fever,  90 
Endotoxins,  414,  425,  466 
English  filter-beds,   883 
English  population  standard,   1026 
English  Tuberculosis  Commission,  137 
Ensilage,  562 
Entameba  coli,  787 
Entameba  histolytica,   122,  123,  945 
Entameba  tropicalis,  787 
Enteritis  anaphylactica,  459 
Entoloma  lividuni  Bull.,  646 
Entomology,   203 
Entomophthoraea,   256 
Environment,  vs.  heredity,  496 

mortality  statistics,  1020 
Enzymes,  in  milk,  559,  561,  602 
Epidemics,  Altona,  cholera,  930 

campaign  against,  368 

cerebrospinal  fever,  197 

control  of,   1003 

definition  of,  367 

diphtheria,  control  of,  168 
in  institutions,  159,  166 

disinfection  in,  1102 

famine  and,  522 

Hamburg,  cholera,  929 

infantile  paralysis,  304 

insect  borne  diseases,  202 

meat  poisoning,  621 

milk  borne,  571 
Boston,   572 

characteristics  of,  99,  578 
diseases  liable  to,  571 
incidence  of,  579 

from  oysters,  638 

paratyphoid,  623 

quarantine  and,  367 

relapsing  fever,  292 

rivers,  due  to,  802 

in  schools,  1092 

suppression,  authority  for,  369 
education  for,  371 
organization  for,  370 
resources  for,  370 

trichinosis,   630 

typhoid,  Alleghany,  Pa.,  943 


1232 


INDEX 


Epidemics,  typhoid,  Ashland,  Wis.,  940 
Butler.,  Pa.,  942 
Chicago,  111.,  944 
Ithaca,  N.  Y.,  942 
Lausen,  933 
Lawrence,  Mass.,  943 
Lowell,  Mass.,  943 
Mankato,  Minn.,  941 
New  Haven,  Conn.,  939 
Plymouth,  Pa.,  938 
Pittsburgh,  Pa.,  943 
typhus  fever,   295 
vital  statistics,  1017 
water-borne,  923 

dysentery,   944,   945 
typhoid,  924 
yellow  fever,   798 
Epidemiology,  of  smallpox,  30 

of  water-borne  typhoid,  96 
Epilepsy,  alcoholic,  339 

hereditary  transmission  of,  511 
mental  deficiency,  336 
notification  of,  1015 
school  children,  1096 
Epileptics,  474,  475 
Epiphanin  reaction,   740 
Epithelioma,  504 

and  flies,  248 
Epizootic  catarrh.    See  Foot  and  mouth 

disease 
Epizootics,  317 
Erclentz,  685,  740,  741 
Ergograph,  741 
Ergot,  517,  645 
Ergotin,  645 
Ergotism,  644 
Erlandsen,  667 
Erlenmeyer,   864 
Eruption,  in  vaccinations,  12 
Erysipelas,  flies,  206,  252,  254 

psychoses,  346 
Erythema  intertrigo,  1183 
Esten,  252,  253 
Esthesiometer,  741 
Estivoautumnal  malaria,  228 
Ether,  210,  264,  704 
Ethyl  aldehyd,  chart  insert,  1046 
Ethylene,  in  illuminating  gases,   726 
Etiology  of  tetanus,  75 
Eucalyptus  oil,  130 
Eugenics,  479 

and  heredity,  470 
immigrants,  353 
mental  deficiency,  337 
record  office,  481 
Europe,  typhoid  death-rate  in,  963 
European  relapsing  fever,  206,  293 
Evans,  192,  260,  545,  1137 


Evaporated  apples,  537 
Evaporation,   in  cooling,   766 

of  food,  536 

of  perspiration,  697 

of  rain  water,   798 
Evaporators,  refuse,  982 
Evolution,  discontinuous,  483 
Ewald,  919 
Excesses,  407 
Excreta,  disinfection  of,  1159 

military  hygiene,  1207 

See  Feces;  Sputum 
Exhaustion  theory,  391 
Exotoxins,   414 
Expansion  of  air,  687 
Expectation  of  life,  table  of,  for  N,  Y, 

City,  1033 
Expiration.     See  Eespiration 
Expired  air,  composition,  663 

reinspiration  of,  742 
Expired   breath,   poisons   in,    738.      See 

also  Eespiration 
Exposure,  to  cold,  753 

to  wet  and  cold,  404 
Expression  of  chemical  results,  854 
Extermination  of  insects,   204 
External  ventilation,  758 
Eyes,  color  of,  500 

of  school  children,   1093 

symptoms  of  trouble,  1093 

Fabrics,  for  clothing,  1200 
Factor  of  safety,  respiration,  750 
Factories,  children  in,   1040 

inspection  of,  1044 

ventilation,  755 

water  necessary  for,  794 
Paget,  1144 
Fagopyrismus,   655 
Fagotoxismus,  705 
Faichnie,  253 
Falcioni,  80 
Falkao,  327,  328 
Fall  turnover,   805 
Familie  Zero,  476 
Families,  cancer  in,  505 

Darwin,  479 

deaf -mutism  in,  506 

degenerate,  476 

Edwards,  478 

Galton,  479 

Kallikak,  477 

tendencies,   501 

Ward,  479 

Wedgwood,  479 
Famine,  406 

pestilence  with,  522 
Famine  fever,  292 


INDEX 


1233 


Fans,  ventilating,  762 

Tantham,  206,  257 

Farcy,  310 

Farms,  sewage  of,  976 

Faroe  Islands,  measles  in,  174 

Farr,  William,  1002,  1033 

Farr's  law,  187 

Farrington,  604 

Fasciola  gigantica,  787 

Fasciola  hepatica,   207,   787 

Fasciolopsis  buski,   787 

Fasciolopsis  fiillebonni,  787 

Fasting,  394,  406 

Fatality   rates,    1007,    1015.      See    also 

Death  rates 
Fatigue,  1040 

natural  immunity,  394 

and  resistance,  405 

toxin  of,  740 
Fats,  animal,  607 

digestion,  in  infants,  557 

as  food,  520 

milk,  556,  557 

determination  of,  593 

in  sewage,  959 

from  tankage,  985 
Fauntleroy,  1209 
Faust,  530,  636 
Favus,  school  children,  1095 
Fay,  505 
Fear,  348 

Feces,  disinfection,  1105,  1171 
carbolic  acid,   1173 
chlorinated  lime,  1159,  1171 
corrosive   sublimate,   1173 
cresols,  1173 
dry  earth,  1173 
formalin,  1155,  1173 
lime,  action  of,  1157 

and  hot  water,  1172 
milk  of,  1172 

removal  of,  955 

typhoid  bacillus  in,  90,  94 

in  water,  817 
Federal  authority,  369 
Federal  Government,  powers  of,  383 
Feeble-minded,  471 

statistics  of,  474,  475,  1015 

See  also  Defectives 
Feeble-mindedness,  333 

family  history,  514 

heredity,  513 

See  also  Mental  deficiency 
Feet,  shape  of,  1201 

soldiers',   1195 
Fehling's  solution,  596 
Feletti,  206,  228 
Ferald,  219 


Ferenbaugh,  319 
Ferment  antitoxins,  421 
Fermentation,  527 

bacteria  in,  1102 

of  foods,  551 

milk,   567 

white  lead,  1052 
Fermented  milk,   565 
Ferments,  in  milk,  559.     See  also  Milk 

enzymes 
Fernald,  360,  473 
Fernbach,   864 
Ferran,  45,  46,  47,  118 
Ferrosilicon,  chart  insert,  1046 
Ferrous  sulphate,  1161 

in  water  purification,  908 
Ferry,  1151 
Fertility,  and  cancer,  505 

and  industrial  occupations,  1043 

race,  999 
Fertilizer,   cesspool  sludge,  978 

garbage,  984 

refuse,  982 

sewage,  967 

tankage,  984 
Fibiger,   303 
Fibrin  ferment,  421 
Ficker,  M.,  388 
Field,  94 

Field  ration,  1191 
Filaria   bancroftii,   206,   221,   246 
Filaria   diurna,   246 
Filaria  loa,  246 
Filaria  niurna,  206 
Filaria  nocturna,  246,  247 
Filaria  perstans,  246 
Filariasis,   206,  246,  247 
File   cutting,  lead  poisoning,   1054 
Filhol,   834 
Filial  regression,  490 
Filipino  scout  ration,  1192 
Filter  galleries,  809 
Filters,  833 

Darnall,  1206 

and   flies,   974 

household,  894 

Ishiji,   1206 

mechanical,  890 

military,  1206 

percolating,  970 

for  rain  water,  797 

roughing,  895 

screening,   895 

scrubbing,  895 

slow  sand,  883 
construction,  886 
control  of,  889 
efficiency  of,  889 


1234 


INDEX 


Filters,   slow  sand,  Mills-Eeinecke  phe- 
nomenon, 890-913 
operation,  887 

sprinkling,  970 

trickling,   970 
Filterable  virus,  6 
Filth  diseases,  781 
Filtration,  American  method,  884 

color  from  water,  829 

intermittent  sand,  968 

iron  from  water,  853 

mechanical,  884 

cities  using  method,  894 

screening,  895 

slow  sand,  883 

cities  using  method,  891 
vs.  mechanical,  893 

of   water,   963 
Finlay,  201,  242,  243,  245 
Finnenbank,  613 
Fire,   disinfectant,  1121 
Fire  damp,  725 
Fireless-cookers,  551 
Fireplaces,   763 
r'ires,  open,  763 
First-aid  packet,   1199 
Firth,  94,  764 
Fisch,  428 

Fischer,  62,  620,  624 
Fish,   207 

bacterial  poisons,  632 

and   goiter,   919 

intermediate  host,  207 

leprosy,  326 

liver  fluke,  207 

and  mosquitoes,  224 

mussel  poisoning,  639 

poisoning,    634 

shellfish.     See  Shellfish 

tapeworms,  207,  635 

tuberculosis,   136 
Fisher,  1145 
Fitch,  398 
Fitz,  672 

Fitz  air  tester,  680 
Fixation  of  complement,  445 
Fixative,  412 
Fixator,    442 
Fixed  virus,  45 
Flachs,  10 
Flack,  666,  667 
Flanagan,  K.,  941 
Flash   method,   pasteurization,   584 
Flat  cars,  disinfection,  1169 
Fleas,  261 

Ceratophyllus,  279 

Ceratophyllus  acutus,  263 

Ceratophyllus  fasciatus,  264 


Fleas,  Ceratophyllus  fasciatus  Bosc,  262 

common  rat,  262 

Ctenocephalus  canis,  263 

dog,  207 

Dipylidium  caninum,  263 

germicides  and,  264 

Hoplopyllus  anomalus,  265 

Indian  rat,   262 

infantile  kala-azar,  207 

Loemopsylla  cheopis,  262 

plague  and,  201,  207,  264 

Pulex,  263 

Pulex  irritans,  263 

Pulex  serraticeps,   263 

pulicides  and,  264 

sand,   1183 

typhus  fever,  263 

Xenopsylla  cheopis,  264,  265 

Xenopsylla  cheopis  Eothsc,  262 
Fleming,   683 

Flexner,   67,    122,   198,   206,   304,   307 
Flies,   247 

anthrax  and,  248,  251,  252,  254,  316 

bacteria  and,   252 

cesspools   and,   979 

cholera  and,  117,  206,  252,  254 

Chrysops,  248 

diarrhea  in  infants,  254 

diseases  conveyed  by,  206,  254 

dysentery,  206,  252,  254 

Empusa  muscae  in,  249 

Entomophthoreae,   256 

epithelioma  and,  248 

erysipelas,  206,  252,  254 

flight,   distance  of,  254 

formaldehyd,   213 

gangrene  and,  250 

garbage  and,   255 

glanders,  206,  252 

Glossina  palpalis,  256 

Haematobia,  248 

Hippelates,  251 

Hodge  fly  trap,  255 

Homalomyia  canicularis,  252 

and  hookworms,   254 

horse   sickness    (Pferdesterbe),   248 

house,   247,   252 

infantile  paralysis,  248,  254,  308 

leprosy  and,  252,  326 

manure  and,  255 

measles  and,  252 

as   mechanical   carriers   of   infection, 
250 

Musea  domestica,  247,  253 

ophthalmia  and,  206,  250,  254 

pappataci  fever,  206,  261 

parasites   of,   256 

|)ai'fisitic  worms  and,  254 


INDEX 


1235 


Flies,   pellagra,   658 

Plilebotomus  pappatassii,   256,  261 

"pink  eye"  and,  206,  250 

plague,   254 

poliomyelitis,  248,  254,  308 

refuse   and,   981 

relapsing  fever  and,   248,   254 

salivarius  and,  253 

sand,  1183 

scarlet  fever  and,  252 

and  sewage,  955,  974 

sleeping  sickness  and,   254 

smallpox  and,  206,  252,  254 

sticky  paper,  214 

Stomoxys  calcitrans,  248,  250,  251 

Streptococcus  equinus  fecalis,  253 

suppression  of,  254 

Tabanus,  248 

table   of   diseases   conveyed    by,    206, 
254 

tsetse,  and  sleeping  sickness,   248 

tropical  sore  and,  254 

tuberculosis.  146,  251 

typhoid,   101,  206,  251,   254 
Floating,   of   oysters,   638 
Floor  space,  per  pupil,  1080 

ventilation,  756 
Flour,   bleached,   544 
Flow  of  rivers,  802 
Flowers  of  sulphur,  211,  303 
Flugge,    142,    198,    199,   388,    664,    685, 

716,  740,  744,  745 
Fluke,   liver,   207 

lung,   207 
Fluoroscin,  test  for  pollution,   817 
Fluorin,  548 
Fluoroscope,  818 
Fly-paper,  sticky,  214 
Foci   of   disease,   1013 
Fog,   711 
Foley.  207 
FoUwell,  A.  P.,  979 
Fomites,   368 

disinfection  of,   1104 

typhoid,  102 
Foods,  516 

acids  in,  523 

adulterants  of,  524 

adulteration  of,  523 

amount  of,  521 

animal,  553 

apples,  evaporated,  537 

ash  of,  520 

beef,  dried,  536 
jerked,  536 

beef  extract,  606 

"bob-veal,"  640 

botulism  and,  626 


Foods,  canned,  541 
canning  of,  540 
ealorifacient,  520 
carbohydrate,  520 
chemical   preservatives,   542 
classification  of,  519 
coloring  of,  525,  544 
composition  of,  520 
condiments,    521 
containers  for,  541 
cooking  of,  550 
decomposed,   526 
diets,  unbalanced,  522 
disguising  of,  543 
desiccation   of,   536 
eggs.     See  Eggs 
evaporation  of,  536 
excessive  amounts  of,  521 
fats,  520 

fermentation  of,  527 
fish.     See  Fish 
and  flies,  251 
fruits,  dried,  536 
fuel  value  of,  519 
function  of,  520 
general  considerations,  516 
and  health,   effect  upon,  517 
idiosyncrasies,  462,  467 
injurious  substances  in,  517 
insufficient,  406,  521 
jellies,  539 
labeling  of,  526,  541 
maize,  657 
meat.     See  Meat 
milk.     See  Milk 
mineral   matter    of,    520,    523 
nitrogenous,   520 
non-nitrogenous,   520 
pellagra  and,  653 
physical  properties  of,  519 
pickling  of,  538 
plant,  520,  644 

beriberi  and,  649 

corn,    656 

potatoes,  648 
plant  poisoning,  ergotism  and,  644 

lathyrism  and,  645 

mushrooms,  645 
preparation,  methods  of,  550 
preservation  of.  See  Food  preservation 
preservatives  of.     See  Food  preserva- 
tives 
preserves,  539 
putrefaction,  527 
putrid,  527 
and  rats,  270 
rice,  649 
salt,  533 


123G 


INDEX 


Foods,  shellfish.     See  Shellfish 
smoking  of,   539 
sources  of,  519 
uses  of,  518 
vegetables,  644 
Food  preservation,  531,  540 
canning,  540 
chemicals,  542 
cold,  533 
drying,  536 
jellying,  539 
pickling,  538 
preserving,  539 
salting,  538 
smoking,  539 
Food  preservatives,  chemical,  542 
arsenic,  549 
benzoate      of      soda,      543,      544, 

545 
benzoic  acid,  543,  544,  545 
borax  and  boric  acid,  546 
formaldehyd,  544,  547 
gum  benzoin,  543 
hydrocyanic  acid,  543 
hydrofluoric  acid,  549 
hydrogen   peroxid,   549 
lead,  543 
"natural,"  542 
potassium  permanganate,  548 
pyroligneous  acid,  542 
salicylic   acid,  544,   547 
sodium  bicarbonate,  549 
sodium  fluorid,  548 
sodium  nitrate,  548 
sulphites,  544,  549 
vinegar  extract  of  spices,  544 
Food-value  of  meat,  606 
Foot,  William,  736 
Foot-and-mouth  disease,  317 
immunity,  318 
in  milk,  577 
prevalence,   317 
prevention,  319 
transmission,  318 
vaccine  virus,  24 
vaccinia,  318 
Foot  pound,  518 

Forbes-Waterhouse   sterilizer,    1206 
Force,  310 
Ford,  646,  648 
Fore  milk,  556 

Foreign  inspection  service,  382 
Forel,  A.,  359 
Forests,  rainfall  and,  798 

water  supply  and,  798 
Formaldehyd,  disinfectant,  1132,  1133 
effect  of,  upon  digestion,  547 
industrial  poison,  chart  insert,   1046 


Formaldehyd,   as   insecticide,    210,   212, 
213,   1135 

physiological  action,  1135 

preservative,   544,   547 

in  rabic  virus,  42 

toxicity  of,   1135 
Formaldehyd  fumigation,  1133 

of  books,   1175 

flaring  top  bucket  for,  1136 

formalin-lime  method,  1137 

limitations  of,  1135 

permanganate-formalin  method,  1136 

spraying  method,  1137 
Formaldehyd  gas,  1133 
Formalin,   deodorant,   1155 

disinfectant,  1133,  1135 

feces,  1173 

fleas  and,  264 

formula  for,  1164 

rabies,  prevention  of,  44 

tetanus  toxin,  428 

See  also  Formaldehyd 
Formula,  for  antiformin,  1160 

for  bichlorid  of  mercury  disinfectant, 
1149 

for    bichlorid    of    mercury    solution, 
1164 

for  carbolic   acid,   1164 

for  chlorin  fumigation,  1145 

for  chlorinated  lime,  1165 

for  clothes  disinfectant,  1174 

for  corrosive  sublimate,  1164 

for  formalin,  1164 

for  formalin-lime,  aluminium  sulphate 
fumigant,  1137 

for  kerosene  emulsion,  220 

for  milk  of  lime,  1164 

for    potassium    permanganate    fumi- 
gant, 1137 

for  rat  poison,  277 

for  vitiation  of  air,  751 
Foster,   173,   194,  546,  664 
Fournier,  62 
Fowls,  anthrax,  405 

epithelioma  of,  248 

slaughter  of,  614 

tuberculosis,  136 
Fraenkel,  144,  184,  427 
Fragilitis   ossium,   509,   1059 
Francione,   463 
Francis,  23,  214,   215,  236 
Frankland,  E.,  729 
Franklin,  65 
Franklin  stoves,  764 
Frantzer,  46 
Franz,  261 
Fraser,    651,    652 
Free   ammonia,   837 


INDEX 


1237 


Freeman,  103 

Freeman's  pasteurizer,  575 

Freezing,  533 

effect  on  hookworm,  130 

machines  for,  766 
Freibank  System,  541,  612 
Freight  cars,   disinfection,   1169 
Frequency,  normal  curve  of,  495 
Fresh  air,  735 

benefits  of,   753 

food  and,  519 

physiological  effects  of,   735 

in  schools,  1080 
Fresh  water  crab,  207 
Fresh  water  snails,  207 
Freud,  348,  350 
Fricks,  292 
Fried  foods,  552 
Friedberger,  E.,  171 
Friedemann,  452 
Friedreich's  disease,  513 
Frier,  103 
Frosch,  318,  577 
Frost,  306,  308,  456,  864 
Frost  milk  test,  601 
Frothingham,  52,  53 
Fruit  butters,  539 
Fruits,  dried,  536 

typhoid   fever,   101 
Frying,  of  food,  552 
Fuel  value,  518 
Fuertes,   J.  H.,  935 
Fugin,   635 
Fugu,  635 

Fuller,  639,  815,  959,  979 
Fuller's  earth,  164 
Fulton,  216 
Fumes,  industrial  prevalence,  1065 

in  mines,  1070 

phosphorus,  1057 

removal  of,  1045 
Fumigation,  1132 

of  air,  1166 

bedbugs,   300 

of  books,  1175 

Clayton  furnace,  1144 

with  chlorin  gas,  1144     ' 

definition,   1100 

with  formaldehyd  gas,  212,  1133 

with  hydrocyanic  acid  gas,  215,  1144 

as  insecticide,  208 

Kinyoun-Francis  furnace,   1143 

with  oxygen,  1146 

with  ozone,  1146 

of  plants,  216 

Pot  method,  sulphur,  1140 

preparation   of  room  for,   208,   1132, 
1167 


Fumigation,   of  railroad   cars,   1169 

rats,  277 

for  scarlet  fever,  183 

of  stables,  1168 

with   sulphur   dioxid,  211,   1138 

terminal,   1104 

See  also  Chemical  disinfectants;  Dis- 
infection;     Formaldehyd     fumi- 
gation;   Sulphur   dioxid   fumiga- 
tion 
Fungi,   destruction  of,   219 

in  water,  855 
Fungicides,  219 
Funk,  522,  651 
Funnel  gases,  278 
Furfurol,  in  rabic  virus,  42 
Furnace,  hot-air,  764 
Furniture,  for  schools,  1081 
Furs,  arsenic  in,   1061 
Furst,  198 
Fusca,  260 

Gabritschewsky,  183 
Gadus  morrhua,  635 
Gaertner.     See  Gartner 
Gaffky,  620,  783 
Gage,  904,  906 
Galactase,  559 
Galeoti,  282 
Gall  sickness,  260 
Galli- Valerie,  254 
Gallon,  grains  per,  854 
Galton,  479,  481,  492,  493,  515 
Galton's  law,  490 
Gangrene,  flies  and,  250 
Garbage,  981 

cans  for,  982 

Cobwell's  reduction,  985 

collection,  982,  986 
mixed,  982,  986 
separate,  982 

digestors  for,  982,  985 

disinfection  of,   1121 

disposal  plants,  location  of,  986 

for  fertilizer,  984 

flies  and,  255 

and  hogs,   feeding  for,   986 

incinerators,  982 

military  hygiene,   1207 

as  a  nuisance,  986 

odors  of,  981 

reduction  of,  982 

reduction  plants,  985 

sterilization  of,  986 

See  also  Eefuse 
Gardner,  180 
Garget,   562,   570 
Garnet  method,  disinfectants,  llJl 


1238 


INDEX 


Garrison,  P.  E.,  655,  658 
Garrison  ration,  1189 
Gartner,  279,  619,  620 
Gas,  coal,  72? 
illuminating,  723 
sewer,  729,  960 
water,  724 
Gas  bacillus,   784 
Gas-heaters,  764 

Gaseous  disinfectants,  1132.  See  Fumi- 
gation 
Gases,  poisonous,  in  air,  721 

in  rain  water,  800 
Gasoline,  bedbugs,  300 
hookworm,  130 

industrial  poison,  chart  insert,   1046 
as   an  insecticide,   218 
lice,   297 
Gastrodiscus  hominis,  787 
Gastroenteritis,  624 
Gastrotoxin,  445 
Gatewood,  J.  D.,  1209 
Gay,  469 
Gaylord,  918 
Gayon,  776 
Geddings,  1148 
Geitel,  708 
Gelatinoids,   520 
Gelien,   163 
General  debility,  402 
General  immunity,  400 
General  paresis,  339.     See  also  Paresis 
Generalized  vaccination,  22 
Gengou,  184,  445,  454 
Gentry,   319 
Geodesy,  768 
Geographic     distribution,     insect-borne 

diseases,  204 
Geometrical  method  of  estimating  pop- 
ulation, 993 
Georgetown,  milk-borne  epidemic,  100 
Geppert,  1110 
Gerber,  327 
Gerhard,  295 
Germ  inheritance,  502 
German  measles,  174 
German  Plague  Commission,  282 
German   Tuberculosis  Commission,   137 
Germicidal  property  of  milk,  571 
Germicides,  choice  of,   1108 
definition,  1100 
penetrating  power,  1116 
table  of  commercial,   1118 
See  also  Chemical  disinfectants 
Gerrish,  62 
Ghon,  141 

Gibson's  method,  420,  423 
Giemsa,  278 


Gigantorhynchus  gigas,  788 

Gigantorhynehus  moniliformis,  788 

Gillespie,  188 

Gillet,  560 

Gillette,  463 

Ginger,   545 

Ginsberg,  165 

Glaisher's  hygrometric  tables,  691 

Glanders,  310 

agglutination  test,  312 

Bacillus  mallei,  312 

diagnosis,  311 

complement  fixation,   313 

flies  and,   206,   252 

immunity,  394 

Mallein  test,  311 

ophthalmic   test,   312 

prevention,  311,  314 

prophylaxis,   315 

Strauss  reaction,  312 

washerwomen,  311 
Glasgow,  sewage  treatment,  966 
Glass  containers,  for  food,  542 
Glazing,  lead  posioning,  1052 
Gley,  412 
Gliadin,  461 

Glossina  morsitans,  206,  257,  260 
Glossina  pallidipes,  260 
Glossina   palpalis,    202,    206,    256,    257, 

258,  260 
Glover,  J.  W.,  1033 
Gloves,  1201 
Glueck,  B.,  361 
Gluten,  520 
Gluttony,  521 
Glycerids,  in  milk,  555 
Glycerin,  pulcide,   264 

variolus  virus,  32 
Glycerinated  vaccine  virus,  5 
Glycocoll,   545 

Gnathostoma  spinigerum,  788 
Gnats,  259 

Goats,  Malta  fever  and,  319 
Goddard,  335,  336,  337,  346,  360,  477, 

478,  514 
Goiter,  916 

cause  of,  917,  919 

endemic  foci  of,  916 
in  fish,  919 

prevention  of,  920 
soil  and,   785 
treatment  of,  919 
in  water,  821,  917 
water-borne,  in  Vienna,  917 
Goiter  wells,  917 
Goldberger,  173,  175,  207,  215,  237,  289, 

296,  655,  659 
Goldman,  1071 


INDEX 


128!) 


Goldmark,    J.,    1043,    1075 

Goler,  574 

Gonococcus,  and  meningitis,   197 

opththalmia  neonatorum,  71 
Gonorrhea,   58 

in  children,  59 

medical  prophylaxis,  67 

and  sterility,  59 
Gordon,  345 
Gorgas,   192,  242 
Gorhani,  637 
Gosio,   1061 

Gosio  's  reaction  for  corn,  657 
Gotehlich,  114 
Gould,  89 
Gout,  hereditary  transmission  of,  508 

overeating  and,  521 
Government  control  of  vaccine  virus,  24 
Gowers,  511 
Grading  of  milk,  563 
Graef,   165 
Graham,  206,  245 
Graham-Smith,  162,  172,  257 
Grancher,   176,   721 
Grassi,   201,   206,   228,   229 
Gravel  deposits,  for  water,  809 
Graveyards,  bacteria  in  soil  of,  779 
Gravity  circulation  of  air,  758 
Gravity  cream,  556 
Gravity   springs,   815 
Gray,   654 
Grease,  of  garbage  reduction,  984 

of  refuse,  982 

skimming  of,  982,  985 
Great  Lakes,   803 
Greeley,  S.  A.,  986 
Green  soap,  tincture  of,  264 
Green  vaccine  virus,  6 
Greene,  72 
Greenish,  659 
Grehant,   722 
Grid  ventilators,  761 
Grieber,  198 
Grief,   348 
Griffith,  139 
Grijns,  651 

Grinders,  for  refuse,  982    ' 
Grippe.     &ee  Influenza 
Grit-chambers,  964 
Grotjahn,  1053 
Ground-itch,  128 
Ground  water,  806 

amount  of,  808 

cleanliness  of,  810 

filter  galleries,   809 

from  limestone,  810 

movement  of,  807 

privies  and,   976 


Ground  water,  rate  of  flow,  808 

relation  to  soil,  772 

from  sand  and  gravel  deposits,  809 

from  sandstone,  810 

sources  of,  808 

springs.     See  Springs 

temperature  of,  808 

typhoid  in,  811 

wells.     See  Wells 
Ground  water   table,   807 
Groups,  biometric,  495 
Grove,   551 

Growth  of  population,  991 
Gruber,  388,  441,  454,   1138  , 
Gruber  reaction,  454 
Guernsey  cows,  fat  in  milk  of,  556 
Guilfoy,  988,  1029,  1033 
Guinea  worm,  207,  947 
Guiteras,  236,  245 
Gulick,  L.   H.,   1097 
Gum  benzoin,  food  adulterant,  526 

as  food  preservative,  543 
Gunn,   126,   1074 

Gunning  method,  milk  proteins,  597 
Guthrie,   163 
Gutierrez,  128,  131 
Guttman,  118 
Gyromytra  esculenta,   648 

Haab,  74 

Hackney,  101 

Haemaphysalis  leachi,  206 

Haematobia,  248 

Haematopinus  spinulosus,  260 

Haemonchus  eontortus,  788 

Haenzsch,   596 

Haffkine,  118,  283 

Hafifkine's   prophylactic,    282,    286 

Hagler,  937 

Hahn,  1051 

Haines,  Thomas  H.,  345 

Hair,  horse,  317 

Hair  hygrometer,  696 

Halberstadter,  69 

Haldane,  664,  669,  670,  671,  672,   673, 

699,    717,    723,    726,    730,    739, 

750,  755,  1063 
Haldane  apparatus,  673 
Hale,  1150 
Halliburton,   547 
HalshofE  Pol,  651 
Halt  order,  1194 
Halteridium,    229 
Hamburg   cholera   epidemic,   930 
Hamilton,    102,    208,    251,    512,    1037, 

1053,  1064 
Hammond,  738 
Hamonic,  58 


1240 


INDEX 


Hampton  contact  beds,  968 

Hanes,  189 

Hanna,  21 

Hansen,  324,  327,  330,  1044,  1075 

Haptophore,   410 

Harbitz,   304 

Harbor,  sewage  in,  956 

Harden,  20 

Hardness  of  water,  table  of,  837.     See 

also  Water 
Harelip,  499 
Haries,  898 
Harmsen,  648 
Harrington,   Chas.,   549,   756,   768,  940, 

1179,    1208 
Harriot,    561 

Harris,  42,  46,  47,  231,  415,  577 
Hart,  Bernard,  350,  359 
Hastings,  590 
Hats,  for  soldiers,   1201 
Havard,   Valery,   1178,   1183,   1208 
Havard  latrine  box,   1207 
Havens,   305 
Haversack  ration,  1191 
Hawaiian  Islands,  leprosy  in,  323 
Hay-Chamberlain  bill,  1184 
Hay  fever,  468 
Hayahsi,  427 
Haygarth,  29 
Hazeltine,  49 
Hazen,    793,    803,    805,    853,    886,    890, 

891,  893,  895,  910,  913,  953 
Hazen 's  theorem,  913,  914 
Head   injuries,   347 
Headgear,  soldiers',  1201 
Health,  influence  of   soil,   773 
Health  administration,  1000 

birth  rates,  use  of,  1000 

diagnostic   laboratory,   1010 

diagnostician   in,    1011 

mortality  statistics,  1017 
Health  officer,   and   abatement   of   nui- 
sances, 387 
Heat,  action  of,  on  food,  550 

dry,    disinfectant,    1121 

in  fumigation,   1134 

and  health,  relation  to,  697 

man's  adaptation  to,  688 

and  milk,  effect  upon,  586 

physiological  effects  of,   1072 

stagnation  of,  742 

transfer  of,   697 
Heat  units,  of  refuse,  981 
Heated   milk,   determination   of,   601 
Heating,  746,  762 

British  thermal  unit,   763 

conduction,    763 

convection,  763 


Heating,  with  dry  air,  763 

electric,   765 

fireplaces,   763 

with   gas,    764 

hot-air   furnaces,   764 

with  hot  water,   765 

with  moist  air,  763 

open  fires,  763 

radiation,   763 

recirculating,  748 

of   schools,   1086 

with  steam,  765 
Hecklers,  1068 
Hedersleben,  629 
Heiden,  1107 
Height   of   recruits,    1180 
Heim,  94 

Heiser,    283,   330,   652 
Hektoen,   93,    164,    173,    175 
Helber,   398 
Heliotropism,   705 
Helium,  in  air,  662 
Heller,  144 
Helmet,   1201 
Helmholtz,  1040 
Helvella,  848 
Hematocytozoa,  228 
Hemenway,  H.  B.,  388 
Hemoglobinuria,  288 
Hemolysins,   443 

auto,  450 

iso,  450 

mushrooms,   648 
Hemolytic  system,  313,  448 
Hemolytic  tests,  444 
Hemophilia,  508 
Henderson,   664,   670,   898 
Henri,  1120 
Henrijean,   80 
Henshaw,  291 
Henson,  236 
Hepatotoxin,  445 
Herdman,  637 
Hereditary     transmission     of     disease. 

See  Heredity 
Heredity,  470 

albinism,  506 

alcohol,  340 

alcoholism,  510 

anaphylaxis,  462 

atavism,  488 

ataxia,  513 

biometry,  492 

brachydactylism,  508 

cancer,  504 

cataract,  509 

the  cell  in,  490 

color  blindness,  506 


INDEX 


1241 


Heredity,        congenital        transmission, 
501 

Daltonism,  506 

Darwin 's  theory,  482 

deaf-mutism,   505 

in  degenerate  families,  476 

De  Vries,  mutation,  483 

diabetes  mellitus,  509 

disease,  tendency  to,  501 

dominance  and,  485 

vs.  environment,  496 

epilepsy,   510 

eugenics  and,  481 

filial  regression,  490 

fragilitis  ossium,  509 

Friedreich's  disease,  513 

Galton's  law,  490 

gout,   508 

hemophilia,  508 

Huntington 's  chorea,  512 

immunity  and,   497 

insanity,   334,   514 

insect-borne  diseases,  202 

in  insects,  287 

isolation,   500 

lead  poisoning,  1050 

leprosy,  328,  505 

marriage,  499 

Mendel's  law,  485 

mental  deficiency,  335,  513 

mental  diseases,  334 

microbic  diseases,  500 

migraine,  511 

mutation,  483 

myopia,  509 

neuropathic,  334,  335 

normal  frequency  curve,  497 

orthostatic   albuminuria,   509 

polydactylism,  509 

preventive  measures,  337 

principles  of,  481 

propagation  of  defectives,  472 

psychoses,  334 

retinitis  pigmentosa,  509 

reversion,  488 

segregation  and,  485 

sex-limited,  498 

syphilis,  502 

ticks  and  Texas  fever,  287 

transmission  of  defects,  499 
of  disease,  498 

tuberculosis,  149,  502 

unit  characters  and,  485 

variation,   481 

Weismann's  views,  484 

Wilson's  theory,  484 

of  Zero  family,  477 
Hering,  Rudolph,  984,  986 


Herma,  303 

Hermans,  738 

Hermite,  1121 

Herschel,  794 

Herter,  544 

Hertz,  534 

Hess,   186,   187,  574 

Hesse,   1065 

Heteromita  zeylanica,  787 

Heterophyes  heterophyes,  787 

Heterozygotes,  487 

Heubner,  557 

Heusinger's   school   desk,   1083 

Hewitt,  252 

Hewlett,  165 

Hexamethylenamin,  110 

Heymann,  685,  740,  742,  743 

Hibernation,    oysters,    637 

Hickey,   C.   H.,   548 

Hides,  611 

anthrax  in,  1073 

disinfection  of,  317,   1073 
Hieracium,   485 
Hill,  666,  667,  682,  685,  699,  705,  742, 

781,  953 
Hinckes-Bird,  ventilator,   761 
Hinds,   217 
Hinton,  446 
Hippelates,  251 
Hippius,  561 
Hippobosca   rufipes,   260 
Hippocrates,  75 
Hippuric  acid,  545 
Hirsch,    297 
Hirt,  727 
Hirudinea,  1183 
Hobdy,  277 
Hoch,  A.,  359,  360 
Hodge,  254 
Hodge  fly  trap,  255 
Hoffman,  Frederick  L.,  505,  545,  1015, 

1066 
Hoffman,   J.   D.,   766 
Hog  cholera  in  meat,  617 
Hogarth,  A.   H.,   1097 
Hogs,  garbage  and,  986 

as  intermediate  hosts,   207 
Holcomb,  68 

Holding  method,  pasteurization,   584 
Holdy,    280 

Hollmann,  324,  326,  328 
Holstein  cows,  fat  in  milk,   556 
Holt,   E.   B.,   60,   359 
Homalomyia  canicularis,   252 
Home  care,  tuberculosis,  156 

typhoid    fever,     108 
Homogenized    milk,    557 
Jlomozygotes,  487 


1242 


INDEX 


Hons,  46 

Hoods,  protective,  1045 

Hookworm  disease,  125 

cleanliness  and,  132 

collateral       benefits       of       campaign 
against,   132 

distribution  of,  125 

education  and,   132  . 

eradication,  131 

flies  and,  254 

immigration,   132 

immunity,    130 

mines  and,  1071,  1074 

modes  of  transmission,  127,  979 

the  parasite,   127 
resistance  of,   130 

personal  prophylaxis,   132 

prevention  of,  130 

soil  pollution,  131 

varieties  of,  126  . 
Hopkins,  57,  398 
Hoplopsyllus  anomalus,   265 
Hopper  sash-light,  761 
Horner,   184,  507 
Horroeks,   321,   730 
Horse  hair,  disinfection,  317 
Horse  meat,  test  for,  454 
Horse     sickness      (Pferdesterbe),     flies 

and,  248 
Horses,   for   antitoxin,   419 
Hospitals,  cross  infections,  176,  719 

death-rates,  1026 

discharge  certificate,  1015 

epidemics  and,  370 

for  the  insane,  354 

statistics,  vital,  1015 

typhoid  in,   103 

ventilation  of,  754 
Hosts,   intermediate,  table  of,   207 

and  parasites,  407 
Hot-air  furnaces,  764 
Hot  •water  heating,  765 
Hotels,  summer,  sewage  and,  976 
Hougardy,  560,  561 
Hours  of  work,  1039 
House  flea,  263 
House   fly,   246,   247 
House  quarantine,  384 
House   sewers,   957 
Household  filters,   894 
Houses,  cooling  of,  765 

lodging,  ventilation  of,  755 

near   privies,   976 

ventilation  of,   748 
Housing    conditions,    and    tuberculosis, 

156 
Houston,  778 
Howard,  247,  251,  303 


Hubbard,   250 

Hiibener,  620 

Hueppe,  566 

Huggard,  692 

Human  tubercle  bacillus,  135 

Human  vaccine   virus,   4 

Humidifiers,   for  cooling,   766 

Humidity,  689 

absolute,  691 

and  air,  cold,  damp,  700 
furnace,    765 
warm,  dry,  701 
warm,  moist,  700 

altitude,   effect  of,   693 

amount  of,  690 

dew-point,  691,  696 

geographical   differences  of,   691 

and  health,  692,  697 

methods  of  determining,   693 
by  deAvpoint,  696 
by  hair  hygrometer,  696 
by  psych  rometer,  694 
by  weighing,  693 

physiological  significance  of,  697 

relative,  691 

in  schools,  1088 

table  of  relative,  87 

and  temperature,  697 

in  textile  mills,  1069 

ventilation  through  w^alls,  693,  760 
Humoral  theory  of  immunity,  439 
Humus,   768 
Hunger,  521,   522 
Hunt,  E.,  531,  919 
Hunter,  440 

Huntington's  chorea,  hereditary  trans- 
mission of,  512 
Huntoon,   198 
Hutchins,  952 
Hutchinson,  326,   720 
Huxley,  T.  H.,  515 
Hyatt,   G.  W.,   891 
Hyatt  filter,  891 
Hybrids.     See  Mendel 's  law 
Hydatid  disease,  207 
Hydatids,  633 

Hydrocarbons,  in  smoke,  709 
Hydrochloric  acid,  in  air,  726 

industrial       poison,       chart       insert, 
1046 
Hydrocyanic    acid,    industrial    poison, 
chart  insert,  1046 

insecticide,  210 

toxicity   of,    543 
Hydrocyanic  acid  gas,  215 

bedbugs  and,  300 

disinfectant,   1132,   1144 

fleas  and,  264 


INDEX 


1243 


Hydrocyanic  acid  gas,  for  rats,  277 

roaches   and,   302 
Hydrofluoric     acid,     industrial    poison, 
chart  insert,  1046 

preservative,  549 
Hydrogen,  in  air,  662 

amount  in  various  gases,  726 
Hydrogen  peroxid,  in  air,  662,  667 

preservative,  549 
Hydrogen  sulphid,  in  air,  727 

amount  in  various  gases,  726 

poisoning  by,  1064 

in  sewers,  728 

toxic  action  of,  727 
Hydrophobia,  39 
Hygiene,  and  immunity,  389 

industrial,  1035 

mental,  331 

military,  1177 

ocular,  706 

personal,  66 
colds  and,  195 
of  soldier,  1194 

of  sex,   61 

See  also  Military  hygiene;   Personal 
hygiene;  Personal  prophylaxis 
Hygienic      conditions,      in      swimming 

pools,  948 
Hygienic  laboratory,  disinfection,  meth- 
od of,  1112 

Pasteur  treatment,  scheme  for,  48 
Hygrometer,  hair,  696 
Hygrometric  tables,  689 
Hymenolepis  diminuta,  207,  273,  788 
Hymenolepis  lanceolata,   787 
Hymenolepis  nana,  207,  788 
Hypersusceptibility,  457 
Hypochlorous  acid,  901 
Hysterics,  in   school  children,   1096 

Ice,  948 

can,  950 

and  disease,  952 

manufactured,  950 

natural,  950 

plate,  951 

typhoid  bacilli  in,  98,  949,  952 

use  of,  in  sewage  disposal,  968,  977 
Ice-box,  534 

Ice  cream,  typhoid  bacilli  in,  94,  100 
Ichthyotoxismus,  634 
Idiocy,  333,  513 
Idiopathic  tetanus,  79 
Idiosyncrasies,  food,  467 
Idiots,  471 

alcohol  and,  340 

sex  instinct  and,  350 
Illegitimacy,  999 


Illuminants,    725.      See  also   Illuminat- 
ing gases 
Illuminating  gases,  723 

coal  gas,  723 

composition  of,  in  percentage,  726 

impurities  in,  725 

legal  requirements  of,   725 

methane,   724 

in  soil,  771 

table   of,   combustion   analysis,   725 

water  gas,  724 
Illumination,  measure  of,  707 

ocular,   706 

See  Light 
Imago,  Stegomyia  ealopus,  241 
Imbecility,   333,  471,  513 
ImhofE  tank,   726,  965 
Immediate  reactions,  18 
Immigration,  control  of,  354 

effect  of,  on  population,  991 

hookworm  disease  and,  132 

mental   diseases  and,  353 

See  Vital  statistics 
Immune   body,   412,   442 
Immunism,   442 
Immunitas  non  sterilans,  401 
Immunity,  389 

acquired,   394 

how  acquired,  395 

active,  395 

agglutinins,  454 

anaphylaxis,  457 

to  anthrax,  316 

antitoxic,  408,  413 

antitoxins  and,  418 

bacillus  carriers  and,  401 

to  chicken  pox,  309 

to  cholera,  118 

complement  fixation,  445 

cytotoxins  and,  445 

to  dengue,  244 

deviation  of  complement,  449 

diphtheria,  165 

drugs,  effect  on,   407 

endotoxins  and,  425 

excesses,  effect  on,  407 

exposure,  effect  on,  404 

to  foot-and-mouth  disease,  318 

general,  400 

hemolysis  and,  444 

in  host  and  parasite,  407 

hypersusceptibility,  457 

to  infantile  paralysis,  306 

to  influenza,  192 

inheritance  of,  497 

insufficient   food,    406 

kinds  of,  390 

latency  and,  403 


1244 


INDEX 


Immunity,  to  leprosy,  324 

local,  400 

lowered  resistance  and,  404 

lysins  and,  440 

to   malaria,   230 

to  measles,  174 

mechanism  of,  390 

mixed,   395 

natural,  393 

opsonins  and,  439 

to  paratyphoid,  623 

passive,   395 

phagocytosis  and,  436 

to  plague,  281 

to  pneumonia,   190 

precipitins,   450 

to  rabies,  49,  51 

relapsing  fever,   294 

to    Eocky    Mountain    spotted    fever, 
291 

to   scarlet   fever,   182 

side  chain  theory,  408 

to  smallpox,  13 

relation  to  vaccine  scars,  17 

susceptibility  and,  394 

to   syphilis,  56 

tetanus  antitoxin  and,  430 

tetanus  toxin  and,  426 

theories  of,  390 

by  toxins,  414 

to  tuberculosis,  147 

to  typhus  fever,  296 

by  vaccines,  396 

vascularity  and,  401 

by  virus,  396 

vitiated  air  and,  407 

wet  and  cold,  effect  on,  404 

the  Wassermann  test  and,  447 

to  whooping  cough,  184 

to  yellow  fever,  237 
Immunology,  389 
Impetigo,  1096 
Impetigo  contagiosa,  from  vaccination, 

22 
Impounding  reservoirs,  804 

algae  in,  805,  827 

odors  of  water  in,  805 

spring  and  fall  turnover,  805 
Inabo,   184 
Inanition,   521 
Inbreeding,  500 
Incineration,  of  ashes,  982 

of  garbage,  982 

of  refuse,  982 
Incinerators,   983,   1207 

odors  of,  984 

smoke   of,  984 
Incision,  vaccination,  9,  10 


Incubation  period,  of  anaphylaxis,  405 

of  measles,  174 

of  toxins,  416 

of  whooping  cough,  185 
Indian  kala-azar,  206 
Indian  corn,  656 
Indian  Plague  Commission,  264 
Indian  relapsing  fever,  293 
Indices,   of   successful  vaccination,   11 
Indirect  infection,  364 
Industrial  conditions,  tuberculosis  and, 

156 
Industrial   diseases.     See   Occupational 

diseases 
Industrial  hygiene,  1035 

accidents,  1038 
preventable,   1044 

anilin  and,  1065 

arsenic  and,  1060 

benzol  poisoning,  1064 

caissons  and,  681,   684,   1073 

cancer  and,  1071 

causes  of  poisoning,  chart  insert,  1046 

in  ceramics,  1052 

clinics   and,    1039 

communicable  infections  and,  1072 

compensation  laws  and,   1045 

cooks  and,  1043 

data  required,  1037 

definition  of,  1038 

in  dusty  trades,  1065 

education,   1039 

efficiency,  1040 

employer  's  liability,  1045 

factory  inspection,  1044 

fatigue,  1040 

fertility  and,  1043 

in  file  cutting,  1053 

fumes,   1045,   1065 

fundamental    considerations    in    pre- 
vention, 1039 

heat,  1072 

hoods,  value  of,  1045 

hours  of  work,  1039 

of  housewives,  1043 

humidity,  1068 

hurry,  1040 

hydrogen  sulphid  poisoning,  1064 

hygienic  conditions,  value  of,  1038 

infant  mortality  and,  1043 

injuries  and  causes,  1045 

inspection  and,  1039 

investigator  's  responsibility,   1036 

laws  and,  1039 

legal  inspector,   1044 

medical  inspector,  1044 

metallic   poisons,    1062 

in  mining,  1070 


INDEX 


1245 


Industrial       hygiene,       minors       and, 
1040 

in  miscellaneous  industries,  1053 

nervous  tension  and,  1040 

noise  and,   1072 

nuisances,  1039 

organized  labor  and,  1035 

overwork  and,  1043 

parasites  and,  1073 

red  lead  and,   1051 

of  saleswomen,  1043 

sedentary  occupations  and,  1046 

of  servants,  1044 

sex  and,   1042 

statistics  of,  errors  in,  1036 

in  textile  mills,  1068 

time,  proper  division  of,  1039 

ventilators  and,  1045 

white  lead  and,  1051 

women  and,  1042 

wood  dust  and,  1070 

of  wool  sorting,  1073 

worker's  responsibility,   1036 

worry  and,  1040 

zinc  and,   1054 

See  Arsenic;   Carbon  monoxid;   Child 
labor;   Dust;   Fumes;    Lead  poi- 
soning ;       Mercurial      poisoning ; 
Mining;  Notifiable  diseases;   Oc- 
cupational  diseases;    Phosphorus 
poisoning 
Industrial  insurance,  158 
Industrial  poisoning,  1037 
Industrial  poisons,  chart  insert,  1046 
See  also  Occupational  diseases 
Industries,  water  required,  794 
Inebriates,  341 
Infant  mortality,  1031 

birth  rate  and,  1031 

in  certain  counties,  1031 

estimation  of,  1032 

industrial  hygiene  and,  1043 

mode  of  expression,  1031 

due  to  water,  914 

working  mothers  and,  1043 
Infantile  diarrhea.     See  Diarrhea. 
Infantile  kala-azar,  207 
Infantile  paralysis,  304 

contact  theory,  306 

death  rates  in,  173 

immunity  to,  306 

insect-borne  theory  of,  307 

modes  of  transmission,  306 

prevalence   of,  305 

prevention  of,  308 

prophylaxis  in,  308 

resistance  of  virus,  306 
Infected  water,  tests  for,  817 


Infection,  362 

air-borne,   719 

carriers  of,  193,  364,  368 

channels  of,  363,  366 

contact,  364 

cross,   176 

destruction  of,  1099 

droplet,  719 

in  eggs,  643 

indirect,  364 

in  lakes,  803 

in  meat,  626 

prevention  of,  608 

prevalence  of,  1017 

missed  cases,   365 

modes  of  transference,  363 

sources  of,   362 

from  trades,  1072 

of  water,  816 

vs.   contagion,   366 
Infectious     diseases.       See     Notifiable 

diseases 
Inflammation,  of  udder,  562 
Influenza,  192 

immunity  and,  192 

isolation  and,  193 

mode  of  transmission,  193 

prophylaxis  in,   193 

psychoses  and,  346 
Infusoria,    826 

Ingestion  infection,  in  tuberculosis,  143 
Inheritance,  of  immunity,  497 

See  Heredity 
Injuries,  head,  347 

incident  to  work,  1045 

notifiable,  1007 
Inlets,   756,  761 

for  schools,  1087 
Inoculations,  cholera,  118 

for   plague,   283 

for  scarlet  fever,  183 

for  smallpox,  27 

for  typhoid,  104 

meningococcic,  198,  200 

for  whooping-cough,  186 

See  Vaccines 
Insanity,   331 

alcohol  and,  338 

cost  of,  475 

definition  of,  333 

hereditary  transmission  of,  334,  336, 
514 

immigration  and,  353 

increase  of,  475 

number  of  cases,  332,  474,  475 

vital  statistics  Of,  1015 

See  Mental  deficiencies;   Psychoses 
Insect  powder,  213 


1246 


INDEX 


Insect-borne  diseases.  201 

bedbugs  and,  299 

definitive  host,  201 

dengue,  244 

epidemics  of,  202 

extermination  of,  204 

filariasis,  246 

fleas  and,  261 

flies  and,  247 

geograpliic  distribution,  204 

infantile  paralysis,  307 

insecticides  and,  208 
.  intermediate   hosts,   201,   206 

kala-azar,  301 

leprosy,  326 

lice  and,   294 

malaria,  228 

migration  of,  204 

mosquitoes  and,  221 

pappataci  fever,  261 

plague,  264,  280 

pulcides  and,   264 

rat  leprosy,  273 

rats  and,  267 

relapsing  fever,  292 

roaches  and,  301 

Kocky  Mountain  spotted  fever,  289 

rodents  and,  264 

sleeping  sickness,  256 

table  of,  206 

Texas  fever,  288 

ticks  and,  287 

trichinosis,  273 

typhus  fever,  295 

yellow  fever,  236 
Insecticides,    208 

arsenate  of  lime,  219 

arsenic,  218 

arsenious  oxid,  219 

arsenite  of  lead,  219 

benzin,  218 

Bordeaux  mixture,  220 

Buhach   insect  powder,   213 

carbon  disulphid,  216 

carbon  tetrachlorid,  217 

formaldehyd,  212,  1135 

gasoline,  218 

hydrocyanic  acid  gas,  215,  1144 

kerosene  emulsion,  220 

Mim's  culicide,  214 

naphtha,  218 

Paris  green,  218 

Persian  insect  powder,  213 

petroleum,  217 

phenol-camphor,  214 

pyrethrum,  213 

relative  efiieiency  of,  209 

resin-lime  mixture,  220 


Insecticides,  Scheele's  green,  218 

sulphur  dioxid,  210,  1138 

table  of,  210 

See  Disinfectants;   Fumigation 
Insects,  201 

blood-sucking,   205 

extermination  of,  204 

hereditary  transmission  in,  202 

as  intermediate  hosts,  201,  207 

suppression  of,  205 
Inspected  milk,  564 
Inspection,  of  factories,  1044 

industrial  hygiene,  1039 

meat,   609,   614 

milk,  581 

service,  foreign,  382 

See  Medical  inspection  of  schools 
Inspectors,  of  meat,  612 
Inspiration.     See  Eespiration 
Inspired  air,  composition  of,  663 
Institutions,  death  rates  in,  1026 

diphtheria   in,   166 

for  insane,  administration  of,  356 
Insurance,  industrial,  158 
Insurance  records,  vital  statistics,  1015 
Interbody,    442 
Intercepting  sewers,   957 
Intermediary  body,  442 
Intermediate  hosts,  201 

table  of,   207 
Intermittent  sand  filtration,  968 
Interstate  pollution,  of  streams,  818 
Interstate  powers,  of  government,  369 
Interstate  quarantine,  383 
Intestinal   flora,    565 
lodin,  1161 
Ipecac,   124 
Ireland,  W.  W.,  340 
Iron,    industrial    poison,    chart    insert, 
1046 

in  water,  852 

in  water  purification,  909 
Iron  ration,   1193 
Irrigation,   of   sewage,  966 
Ishiji  filter,   1206 
Isohemolysins,  450 
Isolation,  384 

in  cerebrospinal  fever,  200 

compensation  for,  386 

degree  of,  385 

geographic,  386 

heredity  and,  500 

in  influenza,  193 

in  leprosy,  329 

limitations  of,  386 

for  measles,  177 

in  smallpox,  36 

for  venereal  diseases,  68 


INDEX 


1247 


Isolation,  for  yellow  fever,  242 

See  also  Quarantine 
Isospora  bigemina,  787 
Issaeflf,   454 
Itchmite,  212,  1095 
Ithaca^  typhoid  epidemic  in,  942 

water-borne  typhoid  in,  96 
Tvy  poison,  1183 
Txodiasis,  287 
Txodidae,   287 
Izal,   1153 

Jackson,  James,  197 

Jacoby,  645 

Jahn,  184 

Jamaica  Plain,  milk-borne  epidemic  at, 

99 
James,  246 
Jams,  539 

Janitors,  of  schools,  1087 
Javelle  water,   1159 
Jazer,  732 
Jeanselme,  327,  328 
Jefferson,  3 
Jellies,  539 
Jenner,  1,  2,  3,  5,  8,  9,  10,  12,  13,  18, 

20,   25,   33,   39 
Jenner 's  golden  rule,  8 
Jensen,  604 
Jequirity,  415 
Jerdey,  732 
Jerked  beef,  536 
Jersey  cows,  fat  in  milk,  556 
Jessen,  739 
Jesty,  Benjamin,  1 
Jewell  filter,  891 
Jiggers,  1183 
Johanncssen,  463 
Johnson,   900,   1137 
Johnstone,    E.    E.,    360 
Johns    Hopkins    Hospital,    typhoid    in, 

103 
Jolles,  560 
Joly,  326 

Jones,  H,  N.,  49,  1172 
Jordan,  460,  464,  497,  577,  -666 
Jorger,  476 

Joshua   Nicholson,   S.  S.,   321 
Joslin,  Allen,  156 
Joule,   766 
Journet,  683 
Jukes  family,  476 

Kaiser,  619 
Kakke,  649 
Kala-azar,  301 

intermediate  hosts,  206,  207 

trypanosomes  and,  261 


Kalbrunner,   213 

Kallikak  family,  477 

Kamp,  1053 

Kangri  cancer,  504 

Kaolin,  164 

Kastle,  251,  560,  561 

Katayama  disease,   207 

Katayama  nosophora,   207 

Kayser,  90,  94 

Keanu,  324 

Kedrowski,  W.   J.,   330 

Keefer,  F.  R.,  1208 

Keens,  1072 

Kefir,  567 

Keith,   S.   C,   949 

Keller,   557 

Kellicott,  475,  477,  480,  487 

Kempner,  260,  627 

Kendall,  91,  566,  1111,   1116 

Kennedy,  28,  320,  321 

Kenotoxin.  740 

Kent,   260 

Kenwood,  755,  761,  764 

Kerosene,  217 

for  fleas,  264 

inseetieidal  coefficient,  210 

for  lice,  295,  297 
Kerosene  emulsion,  formula  for,  220 
Kerr,  25,  71,  280 
Kershaw,  G.  B.,  979 
Keyes,  503 
Khaki,  1200 
Kilborne,  206,  287,  289 
Kimberly,  A.  E.,  979 
Kinderblattern,   29 
King,  128,  131,  229,  289,  496,  1033 
Kinghorn,  257 
Kinnicutt,  722,  979 
Kinyoun-Francis  chamber,   1128 
Kinyoun-Francis  furnace,   1143 
Kionka,  549 
Kirby,  G.  H.,  360 
Kirkwood,  J.  P.,  883 
Kister,  271 
Kitasato,  16,  75,  76,  79,  172,  207,  264, 

325,  328,  427 
Kitashima,  418 

Kjeldahl  method,  milk  proteins,  597 
Klebs-Loeffler    bacillus,    in    ophthalmia 

neonatorum,  73 
Klein,  102,  179,  637,  1158 
Kleine,  257,  258 
Klimenco,  184 
Kling,  307,  310 
Klotz,  711 
Knab,  229 
Knorr,  418,  430 
Knoxville.  103 


1248 


INDEX 


Koan  Nakagawa,  636 

Kober,  62,  251,  546,  645,  648,  932,  934, 

935,  1075 
Koeh,  41,  103,  104,  115,  117,  135,  136, 

141,  229,  231,  234,  257,  259,  277, 

293,  320,  778,  783,  859,  930,  1110, 

1155 
Kocli-Week's  bacillus,  71 
Kocher   919 
KoUe,  104,  106,  114,  118,  119,  282,  441, 

454,  469 
Konoscope,  715 
Konrich,  666,  667 
Koppe,  647 
Korn,  581 

Korsakow's  disease,  338 
Kraepelin,  341 

Kraus,   122,  450,  451,  466,  469 
Kronecker,  683 
Kronig,   1108,  1111,  1148 
Krumwiede,   137 
Kruse,  194,  260,  566 
Krypton,  in  air,  662 
Kuhn,  316 
Kiilz,  648 
Kumyss,  567 
Kupfer's  cells,  437 
Kurth,  179 

Labarraque's  solution,  1159 
Lactalbumin,  556 
Lactase,  421 
Lacterius  rufus,  646 
Lacterius  torminosus,  646 
Lacterius  zonarius,  646 
Lactic  acid,  in  milk,  565,  599 
Lactocaramel,  558 
Lactodensimeter,  600 
Lactoglobulin,   556 
Lactokinase,   560 
Lactose,   558,  596 
Lactosin,  554 

Lagoeheilascaris  minor,  788 
Lakes,  803 

algae  in,  827 

artificial,  804 

Great,  803 

infections  in,   803 

odors  of,  826 

pollution  of,  804 

purification  of  water  of,  803 

quality  of  water  of,  805 

sewage  in,  803,  956 

spring  and  fall  turnover,  805 

stagnant,  805 

stripping,   806 
Lamarck,  J.   B.,  483,  515 
Lamblia  duodenalis,  273 


Lamblia  intestinalis,  207,  787 

Lampson,  147 

Lamus  megistus,  206 

Landsteiner,  179,  304,  306 

Landtman,  627 

Landtsheer,  561 

Langworthy,  C.  F.,  519 

Lanolin,    1200 

Lantz,   280 

Lapage,  C.  P.,  335 

Laplace,  1148 

Lappin,  87 

La  rage,  39 

La  spirillose  des  poules,  206 

Lasts,  Munson's,  1202 

Latency,    403 

Lateral  sewers,  957 

Lathyrus  cicera,  645 

Lathyrus  sativus,  645 

Latrines,  1207 

Laubenheimer,   Kurt,  1154 

Laurans,  327 

Lausen,  typhoid  epidemic,  933 

Lavender,  654 

Laveran,     206,     228,     229,     236,     260, 

924 
Lavoisier,  662 

Lawrence  typhoid  epidemic,  99,  948 
Laws,  compensation,  1046 

for  defectives,  473 

industrial  hygiene,  1039 

meat  inspection,  614 

medical  inspection  of  schools,  1090 

morbidity,    1003 

notification,  1016 

and  pregnancy,  in  industrial  hygiene, 
1042 

of  probability,  493 

of  soil  moisture,   786 

State  morbidity,   1005 

See  Sanitary  law 
Layet,  13,  1054 
Lazarus,  118 

Lazear,  J.,  201,  206,  236 
Leach,  659 
Lead,  arsenate  of,  219 

chart   insert,    1046 

in  containers  for  food,  541 

as    food    preservative,    543 

in  water,  853,  920 
Lead  carbonate,  1049 
Lead  oxid,  1051 
Lead  pipes,  920 
Lead  poisoning,  920,  1047 

abortion,   1050 

cases  of,  923 

chronic,   1049 

colic,  1050 


INDEX 


1249 


Lead     poisoning,     cumulative     action, 
1047 

dust,  1048 

in  earthenware,  1052 

encephalitis,  1049 

file  cutting  and,  1053 

glazing,   1053 

and  heredity,  1050 

in  industries,  1053 

mode  of  contracting,  1049,  1055 

paint  and,  1052 

painters  and,   1050 

potter 's  asthma,  1053 

potter's  rot,  1053 

in  pottery,  1052 

prevalence  of,  1037 

prevention  of,  1054 

red,  1051 

susceptibility  to,   1048 

symptoms  of,  922,  1049 

white,  1051 

wrist  drop,  1049 
Lead  sulphate,   1048 
Leal,  J.  L.,  818 
Leather,  1201 
Le  Blanc,  42,  572 
Leboef,  325 
Lecethin,  531,  554 
Lecky,  68 
Le  Dantie,  77 
Ledbetter,    67 
Lederer,  A.,  914 
Ledingham,  93,  254,  301 
Leeches,  1183 
Leeds,  A.  E.,  891 
LefPmann,   882 

Legge,  1049,  1050,  1052,  1073 
Leggins,  1201 
Legislation,  sanitary,  975 
Legitimacy,  995 
Lehman,   727,  738,   739,  743 
Leichmann,  566 
Leidy,  250,  533,  948 
Leighton,  608 
Leiner,  306 

Leishman,  104,  105,  106,  293,  301,  440 
Leishmania   donovani,   206 
Leishmania  infantum,  207 
Lemke,  94 
Lenhart,  918 
Lenkocidin,  445 
Lentz,  624 
Le  Prince,  223,  232 
Leprolin,  330 
Leprosaria,  329 
Leprosy,  322 

and  bedbugs,  301 

children  of  lepers,  328 
41 


Leprosy,  and  fish,  326 

and  flies,  252,  326 

and  heredity,  505 

immunity,   324 

and  insects,  326 

and  mosquitoes,  327 

nasal  infection,  327 

prevention  of,  329 

quarantine,  376 

rat,  273,  325 

sexual  contact,  328 

transmission,   326 

and  vaccination,   22 

Wassermann  reaction,  330 
Leptodera  pellio,  788 
Leukocytes,  in  immunity,   404 

in    milk,   561 

in  phagocytosis,   437 
Leukomain,  528 
Levaditi,   179,  306,  469 
Levin,  505 
Levine,  575 
Levy,  80,  95,  173,  851 
Lewaschew,  700,  701 
Lewes,  G.  H.,  737 
Lewes,  V.,  727 
Lewin,  1059 
Lewis,  260,  304,  761 
Lewis   and   Kitchen   incinerator,    1207 
Lice,   294 

Algerian  relapsing  fever,  207 

Asiatic   relapsing   fever,   207 

body,  295,  297 

coal  oil,  297 

destruction  of,  295,  297,  1095 

dog,  207 

European  relapsing  fever,  207 

head,  293,  295,  297,  1095 

pubic,   295 

relapsing   fever,   207,   293 

school  children,   1095 

typhus  fever,  207,  278,  296 

wood,  287 
Liceaga,  242 
Liceeides,  295,  297,  1095 
License,  marriage,  994 
Liebig,   520,   606 
Liebreich,  546 
Lies,  328 
Life,  duration  of,  1032 

expectancy  of,   1032 
Life  insurance,  and  syphilis,  57 
Life    tables,    1032 
Light,  705 

effects  of,   705 

intensity,  measure  of,  707 

See  Illumination;   Ocular  hygiene 
Lighting   of   schools,    1085 


1250 


INDEX 


Lime,   1156 

alum,  reaction  with,  907 

arsenate  of,  220 

disinfection  of  wells,  814 

for  excreta,   1157,   1172 

germicide,   1157 

iron   sulphate,   reaction  with,  908 

milk  of,  1156 

resin-lime  mixture,   220 

sewage  precipitation,  966 

slaked,  1156 

and  sulphur  dips,  212 

in  water,  835 

whitewash,  1156 

See  also  Chlorinated  lime 
Lime   water,   678 
Limeola,  260 

Limestone,   water   from,   810 
Limnaeus,  207 
Lindner,  69 
Linen,   for  clothing,   1200 

disinfection  of,  1174 
Linene  thread,  490 
Linenthal,   H.,   1172 
Liuhard,  682 
Linn,  263 
Linnaeus,  326 
Lipase,   560 
Liquid   chlorin,   905 
Liquid  sulphur  dioxid,   1141 
Liquor  cresolis  compositus,  1152 
Lister,   719 
Litharge,  1051 
Lithemia,   521 
Litters,  1189 
Little,  653 
Liver  fluke,  207 
Loa  loa,  206 
Loam,   768 
Lobar  pneumonia,  188 

immunity,   190 

modes   of   transmission,   189 

prevention,   190 

resistance  of  virus,  189 
Lobenhoffer,   919 
Local  immunity,  400 
Lock,  484,  494,  515 
Lockjaw,  75 

Locus  minoris  resistentiae,   501 
Loeffl'er,  172,  278,  318,  577,  1155 
Loemopsylla  cheopis,  262 
Loewenhart,  561 
Loew  's  pasteurizer,  585 
Logwood,   524 

Lombroso,  471,  529,  654,  658 
Londonderry,  S.  S.,  737 
Long,  545 
Longfellow,  303 


Longworthy,  523 

Looss,   128 

Lord,   193 

Lorenz,   165,  343 

Loschia  brasiliensis,  787 

Loschia  buccalis,  787 

Loschia  biitschlii,  787 

Loschia  coli,  787 

Loschia  hartmanni,  787 

Loschia  hystolytica,  122,  787 

Loschia  minuta,  787 

Loschia  nipponica,  787 

Loschia  phagocytoides,  787 

Loschia  tetragena,  787 

Loschia  tropicalis,  787 

Loschia  undulans,  787 

Loss  of  head,  888 

Louis,  295 

Louse.     See  Lice 

Lousiness,  295 

Louvred    outlets,    761 

Lovett,   E.   W.,    307 

Low,  299,  232,  247,  301 

Lowden,  52 

Lowe,  209 

Lowell,  typhoid  epidemic,  943 

Lower  animals,  diseases  from,  362 

Lowered   resistance,   403 

Lubarsch,    '1-40 

Llibberd,  739 

Lucas,  175,  307 

Luce,   1064 

Lumsden,   251 

Lung  fluke,  207 

Lustig,  282 

Lymph,   vaccine,   5 

Lymphocytes,    437 

Lymphoid  stadium,  145 

Lynch,  273,  1209 

Lyon,  512 

Lysins,  440 

Lysol,   1152 

Lyssa,   39 

Lyster  bag,  1206 

Maar,  666 

McClintic,   1111 

Macfadyen,  320,  533,  949 

Macfie,  687,  692,  701,  706,  713,  735,  766 

Mackinaws,  1200 

MacNeal,  W.  J.,  655,  658 

MacNutt,  913,  914 

Macrocytase,  438 

Macrophages,    437 

Madsen,  424 

Magats,    255 

Magnesium,  in  water,  835 

Mair,  100,  639 


INDEX 


1251 


Maize,  656 

Malaria,  228 

anophelinae  and,  206 

bovine,   288 

estivo-autumnal,  228 

immunity  to,  230 

personal  prophylaxis  in,  232 

prevention  of,  231 

psychoses  in,  346 

quartan  fever,  228 

quinin  prophylaxis  in,  233 

tertian    fever,    228 

transmission   of,   229 

tropical,  228 

water-borne,  946 

and  yellow  fever  contrasted,  244 
Malarial  mosquito,  229 
Mai  de  Caderas,  260 
Male.     See  Sex 
Mallein  test,  311 
Malignant  edema,  769,  783 
Malignant  pustule,  315 
Mallory,  172,  179,  184,  398 
Malta  fever,  319 
Mammoth  cave,  810 

Management,     of     epidemic     campaign, 
368 

of  plague  epidemic,  283 
Maneuver    division,    of    U.    S.    Army, 

typhoid  in,  107 
Manganese,  chart  insert,  1046 
Manila,  Bilibid  prison  in,  133 

causes  of  death  in,  1022 

cholera  in,  118 
Mankato,  typhoid  epidemic   in,  941 
Manneberg,  229 
Manning,  Wm.  J.,  766,  1174 
Manson,  201,  206,  229,  246,  301 
Manteufe,  293 
Mantoux,  750 
Manufactured  ice,  950 
Manure,  981 

and  flies,  255 

incineration  of,  984 
Marasmus,  522 
March,  of  soldiers,  1194 
Marchand,  301 
Marching,  1195 
Marchoux,  206,  237,  325,  330 
Marcus,  477 
Marfan,  560,  561 

Margaropus  annulatus,  202,  206,  289 
Marzari,    654 
Marie,  44,  429 
Marine,  918,  919 
Maritime  quarantine,  372 

ballast,  382 

bill  of  health,  377 


Maritime    quarantine,    cargo     disinfec- 
tion, 382 

control  of,  382 

cholera  in,  373 

detention  period,  372 

disinfection  of  ships,  378 

equipment  of  station,  377 

foreign  inspection,  ^ '" 

leprosy  in,  376 

plague  in,  374 

procedures,  376 

quarantinable  diseases,  372 

typhus  fever  in,  375 

smallpox  in,  373 

yellow  fever  in,  375 
Marker,  759 
Market  milk,  565 
Marlatt,  218,  299 
Marmalades,  539 
Marmier,  A.,  899 
Marmot,  265 
Marriage,  consanguineous,  500 

retinitis  pigmentosa   and,   509 

deaf-mutism  and,  505 

death  rates  and,  1028,  1029 

graph  for  ^Michigan,  995 

heredity  and,  499 

leprosy  and,  328 

of  mental  defectives,  337 

registration  of,  996 

syphilis  and,  345 

See  Matrimony;  Vital  statistics 
Marriage  license,  994 
Marriage  rates,  992,  994 
Marriage  statistics,  994 
Marsh  gas,   725 
Martin,  265,  266,  282,  511,  1107,  1112, 

1116 
Martins,  501 
Maver,  291 
Marx,  45,  457 
Mayer,  260 
Mayet,  916 
Mayow,   662 
Mayr,  Franz,   175 
Masa-mova.     See  Ground  itch 
Mason,  252,  253,  846,  953 
Massachusetts     General     Hospital,     ty- 
phoid  in,   103,   108 
Massicot,  1051 
Matches,  1057 
Maternal     transmission,     syphilis     and, 

503 
Matrimony,   Wassermann  reaction  and, 

503.    See  Marriage 
Matson,   832 
Mattauschek,  57,  344 
McCabe,   610 


1252 


INDEX 


McCall  incinerator,   1207 

MeCarrison,  918,  919 

McClintic,  T.  B.,  292,  1116,  1118    ■ 

McClintoek,  209,  1151,  1163 

MeCollom,  80,  229 

McEae,   252 

McCoy,  266,  271,  272,  279,  280,  325 

McCulloch,  605 

McDermott,  1140 

McFadden,  655,  658 

McFarland,  398 

McKeever,  D.,   941 

MeKinnell's  ventilator,  761 

McLaughlin,  A.  S.,  85,  117,  914,  1022 

McNeal,  257 

McPherson,    898 

McVail,   178 

Meader,  93 

Meal  moth,  207 

Mean,  495 

Measles,  172 

and  flies,  252 

immunity  to,  174 

mental,  deficiency  and,  346 

mode  of  transmission,   175 

morbidity  rate,  1010,  1018 

morbidity  statistics,   1008 

prevention  of,  176 

resistance  of  virus,  174 

schools  closed  for,  178 
Meat,  605 

adulterants,   609 

anthrax  and,  617 

actinomycosis  and,  617 

bacteria   in,   619 

botulism,  626 

canning  of,  540 

cholera  and,  617,  619 

classification  of,  612 

composition  of,  605 

condemned,  611,  615,  618 

consumption  of,  605 

cooking  of,  550 

cysticerci  in,  608 

detection  of,  607 

diseases  carried  by,  640 

dried,  536 

horse,  test  for,  454 

infections  in,  626 

inspection  of,  609,   617 

inspection  laws,  614 

inspector  of,  612 

measly,   632 

nutritive  value  of,  605 

parasites  in,  609,  629 

pickled,  538 

powdered,  536 

preservatives  of,  608 


Meat,  raw,  608 

reaction,  606 

slaughtering,  613 

smoked,  539 

spoiled,   608 

sources  of,  607 

test  for,  454,  607 
Meat  poisoning,  618 
Mechanical   filters,   890 

compared  to  slow  sand,  893 
Mechanical  transmission,  201 
Mechanical  ventilation,    762 
Median,  495 

Medical    department   of    army,    organi- 
zation of,  1183 

duties  of,  1186 
Medical  inspection,  of  schools,  1089 

of   lecruits,   1179 
Medical  reserve  corps,  1184 
Medicated  soaps,   1163 
Medlar,   179 
Melier,  241 
Melville,  61 
Melzel,  A.,  723 
Melzer,  750 
Mendel,    334,   337,   415,   470,   485,   486, 

497 
Mendel's  law,  485 
Mendelson,   397 

Meningitis.     See  Cerebrospinal  fever 
Meningococcus,  197 
Mental  adaptation,  349 
Mental  adjustments,  349 
Mental  conflicts,  349 
Mental  deficiency,  339,  350,  472,  513 

alcohol,  339,  340 

causes  of,  335,  339,  346,  347 

heredity  and,  335 

commitment  of  defectives,   336 

hygiene  of,  331 

marriage  and,  337 

Mendel's  law  and,  337 

notification  of,  1015 

prevention   of,   337 

registration,   338 

statistics,  1015 

syphilis  and,  344 

See  also  Defectives 
Mental  diseases,  alcohol  and,  338 

causes  of,  334,  338,  342,  343,  347,  348, 
352,  353 

cost  of,  332 

definitions,    333 

economic  factors,   352 

head  injuries  and,  347 

heredity  and,  334 

hospitals  for,  354 

ijnmigration  and,  353 


INDEX 


1253 


Mental     diseases,     institutional     care, 
332 
mental  causes,  348 
nervous  strain,  1040 
pellagra  and,  343 
prevention   of,   347,   350,   353,   354 
eugenics   and,    337 
in  school  children,  1096 
sex  instincts  and,  350 
See  Psychoses 
Mental  education,  351 
Mental  hygiene,  331.     See  Mental  dis- 
eases 
Mercurial  ointment,  295 
Mercurial  poisoning,  1061 
Mercury,  bichlorid  of,   1148 
fleas,  action  on,  264 
industrial  poisoning,  1062 

chart  insert,  1046 
See  Bichlorid  of  mercury 
Mercaptan,  704 
Merino,  1200 
Merk,  1129 
Merkel,   739 
Metabolism,     effect    of    humidity    and 

temperature,  697 
Metacresol,  409 
Metcalf,  979 

Metastrongylus  apri,  788 
Metchnikofif,  56,  58,  108,  4C1,  413,  417, 
418,  419,  429,  436,  437,  438,  439, 
450,  454,  457,  469,  550,  566,  795 
Methane,  725 
in  coal  gas,  726 
in  illuminating  gases,  726 
in  ImhofP  tank,  726 
in  natural  gas,  726 
in  sewer  gas,  731 
in  water  gas,  726 
Methyl  alcohol,  chart  insert,  1046.     See 

Wood  alcohol 
Methyl  bromid,   chart  insert,   1046 
Methyl  iodid,  chart  insert,  1046 
Metz,  214 

Meyer,  198,  337,  354,  359,  361,  429 
Meyer's  line,  1201 
Mezincescu,  325 
Miasmatic  diseases,  366 
Mice,  207,  267 
Michailow,  118 
Michelis,  425 

Micrococcus  catarrhalis,  194 
Micrococcus  freudenreichii,  567 
Micrococcus   melitensis,    319,    320,    321, 

322,  4.5.5,  456,  577 
Microcytase,    438 
Microcytes,  437 
Microphages,  437 


Microscopy,   of  water,   855 

Middletown,  typhoid  outbreak  at,  100 

Migraine,   511 

Migration,  death  rates  and,  1027 

Miliaria,  1183 

Military  hygiene,  1177 

barracks,   1203 

clothing,  1199 

crematory,  1208 

diseases  of  soldiers,  1182 

disposal  of  excreta,  1207 

first  aid  packet,  1199 

garbage,  1207 

incinerators,   1207 

latrines,  1207 

marching,  1194 

organization  of  medical  corps,  1183 
See  Medical  department 

permanent  camps,  1203 

physical  training,  1203 

rations,  1189 

references,  1208 

recruiting,  1178 

sanitation,  in  camp,  1194 

sanitary  police,  1197 

soldier's  equipment,  1197 

trenches,  1204 

water,  1205 
Milchner,  429 
Milk,   553 

alcoholic   fermentation,   567 

alkaline  putrefaction,  566 

adulteration  of,  568 

bacteria   in,   569 

bacteriological   examination   of,   588 

bacteriological  standards,  558 

bitter,   567 

butter  fat,  557 

certified,   563 

chemical  analysis,  592 

chemical  standards,  558 

chemical  preservatives,  568 

cholera,  117 

classification  of,   562 

colored,  568 

condensed,  579 

cow 's  and  woman 's,  compared,  562 

curd  in,  562 

decomposition  of,  565 

desiccated,   579 

diphtheria  in,  575 

dirt  test,  568 

dirty,   568 

diseases  spread  by,  571 

dried,  537 

drugs  excreted  in,  562 

dysentery  in,  577 

enzymes  in,  559 


1254 


INDEX 


Milk,  fat  in,  557,  593,  595 

fermentation  of,   565 

ferments  in,  559 

"fore,"  556 

germicidal  property  of,  571 

goat's,  Malta  fever  and,  319 

effect  of  heat  on,  586 

heated,  601 
tests  for,   601 

homogenized,  557 

inorganic  salts  in,  562 

inspected,   564 

lactic  acid  in,  566,  599 

legal  requirements,  558 

leukocytes  in,  561 

"life"  in,  559 

Malta  fever  in,  577 

market,   565 

microscopic   tests,   591 

oleomargarine  and,  581 

pasteurization,  582.     See  Pasteuriza- 
tion 

physical  standards,  558 

powdered,  538 

proteins  in,  597 

proteolytic  bacteria  in,  589 

putrid,  566 

reaction  of,   554 

requirements  for  safe  sapply  of,  587 

ropy,   567 

samples  of,  588 

sanitary  standards,  558 

septic  sore  throat  and,  575 

from  sick  cows,  572 

skimming  of,  568 

slimy,  567 

sour,   565 

specific  gravity,  600 

streptococci  in,  590 

sweet  substances  in,  568 

thermal  death  point  of  enzymes,  561 

thickening  agents,  568 

total  solids  in,  558,  592,  593 

tubercle  bacilli  in,  572,  590 

typhoid  bacilli,  94,  590 

ultraviolet  rays  and,  1120 

water  in,  598 

watering  of,  559,  568 

woman's,  562 

whey-products,  562 
Milk-borne    diseases,    diphtheria,     162, 
575 

foot-and-mouth  disease,  577 

incidence  of,  579 

infantile  diarrheas,  577 

Malta  fever,  577 

milk  sickness,  577 

HC-arlet  fever,  181,  575 


Milk-borne  diseases,  septic  sore  throat, 
575 
tuberculosis,  572 
typhoid  fever,  85,  98,  574 
Milk-borne  epidemics.     See  Epidemics 
Milk-borne  outbreaks.     See  Epidemics 
Milk  inspection,  582 
Milk  products,  100,  579 
Milk  serum,  555 
Milk  sickness,  577 
Milk  standards,  558 
Milk  sugar,  558,  596 
Milk  "strip] lings,"  556 
Mills,  273,  913,  946 
Mills-Reinecke  phenomenon,  890,  913 
Mini,  214 

Mim's  culicide,   214 
Minchim,  258 
Minerals,  in  smoke,  709 
Mineral  acids,  in  the  air,  668 
Mineral  dyes,  in  foods,  525 
Mineral  matter,  in  sewage,  959 

in  soil,  769 
Mineralization,   of   sewage,  964 
Miners,  tuberculosis  in,  1071 
Miner's  anemia,  126,  1074.     See  Hook- 
worm disease 
Mining,   1070 
coal,  1070 

"beat  hand"  and,  1071 
feces'  disposal  and,  1070 
moisture,  value  of,  1071 
Minors,  industrial  hygiene  of,  1040 
Minot,  490 

Miquel,  716,  730,  800 
Misbranding,  526 
Missed  cases,  365 
Mita,  S.,  171 
Mitchell,  94,  739 
Mites,'  212,  287 
Mitosis,  490 
Mitzmain,  264,  266,  316 
Miyake,   271 
Moezutkowski,  293 
Mode,   496 

of  a  normal  curve,  495 
Mode  of  transmission,  of  anthrax,  316 

of  cerebrospinal  fever,  197 

of  chicken  pox,  309 

of  cholera,  115 

of  common  colds,  194 

of  diphtheria,  160 

of  dengue,  244 

of  foot-and-mouth- disease,  317 

of  glanders,  310 

of  gonorrhea,  58 

of  hookworm,  127 

of  influenza,  193 


INDEX 


1255 


Mode  of  transmission,  of  kala-azar,  301 
of  leprosy,   326 
of  lobar  pneumonia,  189 
of  malaria,  228 
of  Malta  fever,  319 
of  measles,  175 
of  mumps,  187 
of  plague,  264,  280 
of  pneumonia,  189 
of  poliomyelitis,  306 
of  rabies,  41 
of  relapsing  fever,  292 
of  Eocky  Mountain  spotted  fever, 

289 
of  scarlet  fever,  179 
of  sleeping  sickness,  256 
of  smallpox,  30 
of    syphilis,    54 
of  tetanus,  76 
of  tracoma,  69 
of  tuberculosis,   141 
of  typhoid,  94 
of  typhus  fever,  295 
of  whooping  cough,  184 
of  yellow  fever,  236,  241 
Modes,  of  spread.     See  under  each  dis- 
ease 
of  transference,   363 
Model  registration  law,  996 
Model  state  morbidity  law,   1005 
Moisture,  in  fumigation,   1134 
Mohler,  24,  314,  574,  609 
Moizard,  176,  721 
Molts,  in  hookworm  disease,  127 
Monas  leus,  787 
Monas  pyophila,  787 
Monospora,  438 
Montagu,  28 
Montana  Peak,  1201 
Montgomery,   269 
Moon,  41 

Moore,  328,  344,   766,  909,  1158 
Mora,   561 
Morax,  429 
Morbidity   laws,    1003 
Morbidity  notification,  1011 
Morbidity  rates,  1014 
of  cities,  1008 
crude,  1014 

of  diphtheria,   1008,  1011 
factors  influencing,  1015 
fatality  rate  and,  1015 
hospital  statistics,  1015 
insurance  records  and,  1015 
of  measles,   1008,  1010 
occupational  diseases  and,  1016 
of  scarlet  fever,  1006 
of  smallpox,  1002 


Morbidity  rates,  specific,  1014 

of  states,  1008 

of  typhoid,  1008 
Morbidity  statistics,  1001 

authority,  1003,  1005 

model  state  law,  1005 

nature  of  information  secured,  1010 

list  of  notifiable  diseases,  1004,  1006 

physician's  responsibility,  1004,  1007 

souice  of   data,   1007 

source  of  errors,  1013 

standard   notification   blank,    1012 

in  the  United  States,  1003 

uses   of,   1013 

See    Morbidity    rates;     Notification; 
Kegistration 
Morganroth,  411,  581 
Morons,  471 
Morphinism,   342 
Morris,  316 
Morrow,  62,  63 
Morse,  101,  986 
Mortality  rates,  1015 

of   diphtheria,    1008 

of  measles,  1008,  1018 

of  smallpox,  1018 

of   typhoid,    85,    88,   935,   963,    1008, 
1018 

of  typhus  fever,   1018 

See  Death  rates 
Mortality   statistics,   1017 

in  health  administration,  1017 

standard  death  certificate,  1019 

sources  of  data,  1019 

sources  of  error,  1013,   1020,   1023 

United  States  area  for   registration, 
1018 

in  the  United  States,  1018 

uses  of,  1023 

See    Death    rates;    Mortality    rates; 
Eegistration 
Mosca  brava,  260.     See  also  Stomoxys 

caleitrans 
Moser's  serum,  183 
Mosquitoes,  221 

Aedes  calopus,  230,  236' 

anopheles,    221,    222,    228,    229,    230, 

244,  246.     See  Anopheles 
breeding  places  of,  223,  225 

culex,   221,   222,   228,   230,   236,   239, 

245,  246.     See  Culex 
destruction  of,  223,  228 
diseases  conveyed  by,  228 
filariae  and,   246.     See  Filaria 
flight  of,   221,  241 
formaldehyd  and,  212 
hibernation  of,  223 
intermediate  hosts,  206 


1256 


INDEX 


Mosquitoes,  life  history  and  habits  of, 
221 

petroleum  and,  217 

Panama  larvicide  and,  225 

pyrethrum  and,  213 

in  refuse,   981 

screening,   226 

Stegomyia  calopus,  221,  222, 
228,  236,  239,  240,  241,  244, 
947 

Stegomyia  fasciatus,   236 

suppression  of,  226,  232 

transmission  by,   229 
of  dengue,  244 
of  filariasis,  246 
of  leprosy,  327 
of  malaria,  229 
of  Malta  fever,  220 
Moss,  163 
Mosso,  683 

Mountain  sickness,  682 
Movements,  of  air,  685 
Muck,   770 
Mucor  mucedo,   1062 
Mullan,   E.   H.,   359 
Miiller,  49,   723 
Mumps,   187 
Miinch,  293 
Munson,   1203 
Munson  last,  1201 
Murchinson,  729,  781 
Muridae,  267 
Mus,  267 

Mus  alexandrinus,  268,  270,  274 
Mus  decumanus,  268 
Mus  musculus,  268 
Mus  norvegicus,  268,  273,  274,  325 
Mus  rattus,  268,  269,  270,  272,  274 
Mus  rattus  decumanus,  260 
Musea   domestica,    247,    249,    253,    327 

See  Flies 
Musca  leprae,  326 
Muscarin,  550,  617 
Musgrave,  945 
Mushroom  poisoning,  645 
Mussel  poisoning,  639 
Mussels,  typhoid  fever  and,  100 
Mustard,  545 
Mutation,  483 
Myelocytes,  437 

Myopia,     hereditary     transmission     of, 
509 

posture  and,   1082 

in   school  children,   1093 
Mysomyia,  229 
Mytilotoxin,  640 
Mytilus  edulus,  639 
Myzorhynchus,  229 


Nacht,  260 

Nacke,  P.,  340 

Naegeli,  134 

Nagana,  206,  260 

Nagel,    699 

Nageli,  729 

Nagier,  910 

Nankivell,  165 

Naphtha,  218 

Naphtha  grease  extractor,  982 

Naphthalene,  210,  264,  1154 

Naphthols,  1154 

Narcotics,  342 

Nash,    101 

Nastin,  330 

National  quarantine,  383 

Nationality  death  rates,  1025 

Natural  gas,  726 

Natural  ice,  950 

Natural  immunity,  393 

Natural  increase,  992,  999 

Naunym,  509 

Nebulosa,  260 

Necator  americanus,  126,  728 

Neech,   180 

Negri  bodies,  52 

Negroes,  hookworm   among,   130 

Neisser,  62,   163,  449,  453,  454 

Neisser-Wechsberg  phenomenon,  449 

Nelis,  53 

Nelms,  Sarah,  1,  2 

Nelson,    303 

Nematoda,  788 

Nematodirus  gibsoni,  788 

Nencki,  529 

Neon,  662 

Nephelometer,   398 

Nephrotoxin,   445 

Nernst,  425 

Nervous    diseases,    of    school    children, 
1096 

Nervous    system,    transmission    of    de- 
fects, 499 

Nessler's  reagent,  838 

Netter,  191,  639 

Neuman,   145,  237 

Neurasthenia,  1096 

Neuropathic  conditions,  336 

Neuropathic   constitution,  334 

Neuroryctes  hydrophobiae,  52 

Neurotoxin,  445 

Neustaedter,  308 

Newark,  water-borne  typhoid  in,  97 

New  Haven,  typhoid  epidemic  in,  939 
water-borne  typhoid  in,  96 

Newman,  177,  575,  581,  604 

New  Orleans,   cholera  in,   112 

Newport,    103 


INDEX 


1257 


Newsholme,    159,    172,   496,    638,    1002, 

1017,   1033 
New  York,  death  rates  in,  1030 

cholera  in,  112 
Nice,  1175 
Nichols,  952 

NicoUe,  57,  69,  175,  207,  263,  296 
Nicotin,   210 

Nietotherus  africanus,  787 
Nictotherus  faba,  787 
Nietotherus  giganteus,  787 
Nigra,  260 

Nitrates,  in  water,  844 
Nitrification,  of  sewage,  971 
Nitric  acid,  in  rabies,  44 
Nitrobacter,   776 
Nitrobenzol,   210 
Nitrogen,  in  air,  662,  665 

amount  of,  in  various  gases,  726 

hygienic   significance  of,  665 

in  milk,  554,  597 

in  sewage,  959 

in  sewer  gas,  731 

in  soil,  770 

in  water,  837 
Nitrogen  cycle,  773 
Nitroglycerin,   chart  insert,   1046 
Nitrosobacteria,  775 
Nitrosococcus,   775 
Nitrosomonas,  775 
Nitrous  gases,  chart  insert,  1046 
Nits,  297,  1095 
Nitsch,  45 
Nochard,  41 
Nocht,   278 
Nogier,   1120 
Noguchi,   7,   41,   56,   57,    70,   206,   304, 

344 
Noise,    1072 
Nordlinger,  817 
Normal  frequency  curve,  494 
North  African  relapsing  fever,  293 
Nose,    and   throat,    of    school   children, 

1094 
Nothsehlachtung,  613 
Notifiable  diseases,   1004 

authority,  1003,  1005 

in  certain  states  and  cities,  1007 

communicable,   1004,  1006 

diphtheria,   1011 

disease  incidence,   1015 

epilepsy,   1015 

foci  of,  1013 

injuries,  1007 

measles,  1010 

mental  deficiency  in,  1015 

occupational,   1005,   1007,   1016,   1038 

physicians'  duties  in,   1004,   1009 


Notifiable    diseases,    standard    notifica- 
tion blank,  1012 

tuberculosis,  154 

See  Registration;   Vital  Statistics 
Nott,    229 
Notter,  764 
Novy,  257,  258,  301,  413,  530,  547,  640, 

645 
Noxe,  655 
Nuisances,   386 

abatement  of,  387 

definition  of,  386 

garbage,  986 

kinds  of,  387 

school  near,   1079 

sewage  plants,  973 

trade  wastes,   974 
Nurse,  care  in  typhoid,  108,  110 
Nutmeg,   545 

Nuttall,  172,  266,  326,  440,  452 
Nyhofie,    G.    C,    1050 
Nyssorhyncus,  229 

Obermeier,  206,  207,  293 
Occupation,  in  census,  991 
Occupational  diseases,  1035 

classification  of,  1046 

control  of,  1017 

definition,  1038 

glanders,  310 

hookworm,  1074 

humidity  and,  1068 

injurious  substances,   1047 

Massachusetts     protective     measures, 
1055 

notifiable,    1005,   1007 

notification  of,   1016,   1038 

physical  examinations,  1017 

physician  and,  1012,  1016 

potter 's  asthma,   1053 

potter  's  rot,   1053 

prevalence  of,  1017 

prevention  of,  1039 

tuberculosis,  1074 

wool  sorter's  disease,  1073 

See    also    Arsenical    poisoning;    Car- 
bon monoxid ;  Child  labor ;  Dust ; 
Industrial     hygiene ;      Industrial 
poisons,  chart  insert;   Lead  poi- 
soning;     Mercurial      poisoning; 
Mining ;       Notifiable       diseases ; 
Phosphorus  poisoning 
Occupational  poisons,  chart  insert,  1046 
Ocular  hygiene,  706 
Odors,  703 

algae,  due  to,  827 

of  bedbugs,  299 

of  cesspools,  978 


1258 


INDEX 


Odors,   destruction  of,   1100 
due  to  organisms,  826 
of  garbage,  981 
'  incinerators  and,  984 
match  factory  and,  1057 
physiological  significance  of,  703 
privies  and,  976 
reduction  plants  and,  986 
removal  of,  705 
sewage  disposal  and,  973 
of  sewer  gas,  729 
significance  of,  703 
of  soil,  778 
source  of,  703 
of  trade  wastes,  975 
ventilation  and,  704 
in  water,  805,  823,  857 
Oenothera  laniarckiana,  483 
Ofeelman,  252 
Ogden,  H.  N.,  979 
Ohlniiiller,  666 
Oil  pinus  palustris,   210 
Oils,  for  lice,  297 
and  odors,  826 
Oleomargarine,  525,  581 
Oliver,  130,  714,  722,  1046,  1048,  1049, 

1053,  1058,   1063,  1071,   1075 
Onchosphere,   207 
Ophthalmia,  birth  statistics,  1001 
contagious,  206 
flies  and,  250,  254 
Ophthalmia  neonatorum,  69,  71 
aqua   chlorini,   73 
argyrol,  73 

legislation  regarding,  74 
prevalence  of,  71 
prevention  of,  72 
protargol,  73 
reporting  of,  1013 
silver  nitrate,  73 
Ophthalmic  test  for  glanders,  312 
Opisthorchis  felineus,   787 
Opisthorchis  noverca,  787 
Opsonic  index,  440 
Opsonins,  439 
Orchitis,    mumps,    187 
Orenstein,  223 
Organic  matter,  in  water,  837,  915 

in  smoke,   709 
Orlandi,  771 

Ornithodorus   moubata,    206,    293 
Ornithodorus  savignyi,  295 
Orr,   F.  I.,   334 
Orsat  tube,  675 
Orthostatic  albuminuria,  509 
Orton,  S.  T.,  360 
Osborne,  415,  461,  462,  671,  755 
Osgood,  307 


Osier,  57,  59,  60,  502,  512,  630,  648 

Ostertag,  572,  609,  640 

Otto,  237,  899 

Outbreaks.     See  Epidemics 

Outlets,  756 

air,  for  schools,  1087 
louvred,  761 
Ovum,  492 
Owen,  Eichard,   630 
Oxalic  acid,  chart  insert,   1046 
Oxaluria,  521 
Oxford,  156 
Oxidation,  of  sewage,  969 

and  streams,  self -purification  of,  880 
Oxygen,  663 

amount  in  various  gases,  726    • 

in  body,  663 

diminished,  effects  of,  737 

disinfectant,   1146 

dissolved,   850 

hygienic  significance,  663 

in  milk,  554 

removed  by   illuminants,   725 

in  sewage,  958 

in  sewer  gas,   731 

in  water,  848,  961 
Oxyuris  vermicularis,  788,  947 
Oyster  beds,  972 
Oysters,  637 

cholera  in,   637 

epidemics  from,  638 

fattening,   638 

floating,  638 

hibernation   of,   637 

scoring  of,  in  B.  coli  test,  637 

typhoid  in,  100,  637 
Ozone,  665 

to  destroy  color,  829 

as  disinfectant,  1146 

for  water  purification,  897 
Ozonizer,  897 

Packard,  A.  S.,  247 

Page,  165 

Painter's  lead  poisoning,  1050 

Palate,  cleft,  499 

Pallas,  269 

Palmquist,  664,  672,  673 

Pamphlets,  disinfection  of,  117 

Panama,  larvicide  used  at,  225 

Pandemic,  definition  of,  368 

Panpoukis,  49 

Pan  rack,  for  burning  sulphur,  1141 

Panum,  529 

Pappataci  fever,  206,  261 

Parafiin  epitheliomas,  504 

Paraffin  oil  lamp,  725 

Paraform,  210,  1133 


INDEX 


1259 


Paragonimus     westermani,      207,     636, 

787 
Paralysis,  in  Pasteur  prophylactic  treat- 
ment, 49 
postdiphtheritic,   169,  421 
Paramoeba  hominis,   787 
Paranoia,  339 
Parasites,  786 

animal,  in  meat,  629 
in  animals,  609 
blood-sucking,  205 
in  diseases  of  occupation,  1075 
ecto-  and  endo-,  203 
flies  and,  254 
on  maize,   654 
in   soil,   786 
table  of,  in  man,   787 
temporary  and  permanent,  203 
in  vegetables,  644 
Paratyphoid  fever,   623 
immunity  in,  624 
prevention   of,  625 
toxin  of,  625 
Paratyphoid  infection,  517,  531 
Paresis,     339,     343.       See     also     Psy- 
choses 
Paris,  water-borne  typhoid  in,  97 
Paris  green,  218 
Park,  80,  137,  164,  166,  167,  172,  198, 

952,  1162,  1163 
Parker,  W.  N.,  236,  515 
Parkes,   755,   761,   764 
Parlor  cars,  disinfection  of,  1170 
Parry,  659 

Parsons,  H.  deB.,  986 
Parthenogenesis,   492 
Passive  immunity,  395 
Passy,  704 
Pasteur,  44,  46,  119,  316,  391,  541,  717, 

719,  783,  851 
Pasteur-Chamberland  filter,   895 
Pasteur  treatment  for  rabies,  45 
care  during,  49 
complications  of,  49 
contraindications  to,  51 
diagnosis  of  rabies,  in  dogs,  52 
fixed  virus,  45 
immunity  in,  49 
preparation  of  virus  in,  45 
.  results  of,  50 
street  virus,  45 
when  to  give,  51 
Pasteurization,   582 
"bottle"  method,  585 
holding   method,    584 
methods  of,  584 
Pasteurized  milk,  rickets  in,  583 
scurvy  in,  583 


Pasteurizers,   Freeman,   585 
Loew,  585 
Straus  home,  585 
Pastia,  306 
Patent  medicines,  mental  diseases  and, 

342 
Paternal  transmission,  of  syphilis,  502 
Paterson,  E.  C,  1161 
Pathogenic  microorganism,  390 
Patton,  289,  359,  361 
Paul,   685,   740,   741,   1050,   1108,   1111, 

1148 
Paupers,  number  of,  475 
Pearson,  490,  492,  515,  1153 
Peat,  770 
Pedieuli,  294 

Algerian  relapsing  fever  from,  207 
European  relapsing  fever  from,  206 
leprosy  from,  326 
Pediculus   capitis,    207,    293,    295,    297 

1095 
Pediculus  corporis,  295 
Pediculus  humanus,  295 
Pediculus  pubis,  295 
Pediculus  vestimentis,  207,  293 
Pellagra,  653 
corn  and,  656 
diet  and,  517,  522 
mental  diseases  from,  343 
photodynamic   theory   of,   655 
prevention  of,  657 
Pelletier,  124 
Pembrey,  699 
Pemmican,  1193 
Pemphigus  contagiosus,  1183 
Penicillium  brevicaule,  1061 
Pennington,  642 
Pennyroyal,   228 
Pennyroyal  oil,  210 
Pepper,  black,  545 

Cayenne,   545 
Peppermint,  oil  of,  210,  228 
Pepsin,  421 
Percolating  filters,  970 
Perflation,  759 
Pericarp,  of  rice,  649 
Peridinium,  858 

Period,  of  incubation.     See  Incubation 
period 
of  detention,  372 
Periplaneta  americana,  301 
Periplaneta  australasiae,  301 
Perl,  89 
Perlsucht,  616 
Permanent  hardness,  834 
Permanganate-formalin  method,  1136 
Permanganate  of  potash,  as  germicide, 
906 


1260 


INDEX 


Permeability,  of  soil,  770 
Pernot,  643 

Peroxidase  tests,  milk  in,  603 
Peroxidases,  destroyed  by  milk,  560 
Persian  insect  powder,  213 
Personal  hygiene,  mental,  352 

sanitary  habits  in,  366 

of  sex,  66 

of  soldier,  1194 

See  also  Personal  prophylaxis 
Personal   prophylaxis,    in    cerebrospinal 
fever,   197 

in  cholera,  120 

in  diphtheria,  169 

in  filariasis,   247 

in  glanders,  315 

in  influenza,   193 

in  malaria,  232 

in  plague,  285 

in  pneumonia,  192 

in  typhoid,   110 

in  typhus  fever,  298 

See  also  under  each  disease 
Perspiration,  697 
Pertussis.     See  Whooping  cough 
Pestilence  and  famine,  522 
Pestis  minor,  285,  374 
Peters,  739 
Petri,  581,  718 
Petroleum,    217 

chart  insert,  1046 
Petrosphere,  661 
Petruschky,  93,   165 
Pettenkofer,    102,    113,    671,    697,    704, 

719,  737,  771,  784,  807,  881 
Petterson,  307,  664,  672,  673 
Petterson-Palmquist  method,  675 
Pfeiffer,   104,   106,   117,   118,   192,   441, 

454,  457 
Pfeiffer 's  phenomenon,  441,  865 
Pfeiffer 's  reaction,   115 
Pferdesterbe,  248 
Phagocytes,  437 
Phagacytosis,  436 
Phalin,  648 
Pheln,  28 
Phenol,  1151 

in  antitoxin,  422 
fleas  and,  264 

industrial  poison,  chart  insert,   1046 
lice  and,  297 
in  Malta  fever,  322 
in  rabic  virus,  42 

See  Carbolic  acid ;    Carbolic  coefficient 
Phenol-camphor,   214 
Phenolsulphonic  acid  test,  845 
Phelps,  979,  1032,  1107,  1112 
Phenylhydrazin,  chart  insert,  1046 


Philadelphia,    typhoid    from   watercress 
in,    101 
water-borne  typhoid  in,  96 
Philip,  134 
Philocytase,  442 
Phipps,  2 

Phlebotonius  duboscqi,  259 
Phlebotomus  pappatasii,  206,  244,  256, 

261 
Phloridzin,   394 
Phlyctenular  keratitis,  69 
Phosgene,  chart  insert,  1046 
Phosphoric  acid,  in  jellies,  359 
Phosphorism,   1059 

Phosphorus,     industrial     poison,     chart 
insert,   1046 

for  rats,  etc.,  276 

red,  1056 

white,  1056 
Phosphorus  paste,  for  roaches,  303 
Phosphorus  poisoning,   1056 

fragilitas  ossium,  1059 

match  making,  1056 

prevention   of,   1059 
Phosphorus  sesquisulphid,  1059 
Phosphureted    hydrogen,    chart    insert, 

1046 
Phossy  jaw,  1058 
Photodynamic  theory,  655 
Photometers,  707 
Phthirius  pubis,  295 
Phthisiophobia,  154 
Phthisis.     See  Tuberculosis 
Physaloptera  caucasia,  788 
Physaloptera  mordens,  788 
Physical  disinfectants,  1119 

boiling  of,  1122 

burning  of,  1121 

dry  heat,  1121 

electricity,  1121 

light  rays,  1119 

steam,  1122 

sunlight,  1119 

ultraviolet  rays,  1119 
Physical  training,  1203 
Physician,   duty   of,   in  vital   statistics, 
1009 

function  of,   1009 

occupational  diseases  and,  1016 
Physicochemical  methods,  disinfectants, 

1111 
Piana,  206 
Pianese,   207 
Pickard,   94 
Pickling,   538 

Picric  acids,  chart  index,  1046 
Pictet,  533 
Pigeon,  fan-tail,  489 


INDEX 


1261 


Piggery,   986 
Pigs,  garbage  and,  986 
■Pike,  207 
Pilez,  57,  344 
Pink  eye,  208,  250 
Pintsch  gas,  for  rats,  278 
Pipes,  draining  filter  beds,  968 

lead  service,  920 
Piroplasma,   289 
Piroplasmosis,   228 
Pirquet,  458,  462,  466,  467 
Pitometer,  794 

Pittsburgh,  typhoid  epidemic  in,  943 
Place,  181 
Place  diseases,  203 
Placental  transmission,   502 
Placentolysin,  445 
Plague,  280 

B.  pestis,  207,  281 

bedbugs  and,  266 

bisulphid  of  carbon  and,  217 

bubonic,  280 

campaign  against  rats,  284 

Ceratophyllus  acutus  and,  263 

Ceratophyllus    fasciatus    and,    263 

Ctenocephalus  felis  and,  263 

endemic  foci  of,  283 

immunity  to,  281 

management  of  an  epidemic,  283 

fleas  and,  207 

flies  and,  254 

Hafekine's   prophylactic,    282,    286 

inoculations,  283 

the  marmot  and,  265 

personal  prophylaxis,   285 

pestis  minor,  285,  374 

pneumonic,  280 

prevention  of,  285 

quarantine  in,  284,  374 

in  rats,  271 

relation  to  rats  and  fleas,  264 

resistance  of  rats  to,  272 

septicemic,  280 

and  squirrels,   265,  279 

swine,  in  meat,  617,  619 

and  tarbagan,  265 

vaccine  in,  282 

and  Xenopsylla  cheopis,  207,  264 

and  Yersin's  serum,  283 
Plain  settling  tanks,  965 
Plankton,  855 
Plant  antitoxins,  421 
Plant  foods,  644 
Plant  fumigation,  216 
Plant  sprays,  219 
Plasmodium  falciparum,   206 
Plasmodium  malariae,*  206 
Plasmodium  vivax,  206 


Plaster-of-Paris,  3-03 
Plate  ice,  951 

Platintim-cobalt,  color  solution  of,   829 
Platinum   loops,    1114 
Playgrounds,  1079 
Plehn,  234 
Plenum  system,  762 
Plerocercoids,  207 
Plett,  1 

Pleuropneumonia,  396 
Plimmer,  260 
Pliny,  789 
Plotz,  296 
Plowright,  647 

Plumbo-solvent  action,  of  water,  921 
Plumbism.     See  Lead  poisoning 
Plumert,  327 

Plymouth     typhoid     epidemic,     water- 
borne,  96,  938 
Pneumococcus,   188,   189,   191,   194,   197 
Pneumonia,  188 

immunity  to,  190 

mode  of  transmission  of,  189 

personal  hygiene  in,   192 

prevalence  of,  188 

prevention  of,  190 

resistance  of  virus  in,   189 

wool  sorter's,   1067,   1073 
Pneumonia  carriers,  191 
Pneumonia  epidemics,   188 
Pneumonia  groups  or  strains,  188 
Pneumonic  plague,  280 
Pneumonokoniosis,  713,  1066 
Poellmann,  477 
Poisoning,  buckwheat,  655 

fish,  634 

meat,  618 

muscarin,  647 

mushroom,  645 

mussel,  639 

from  plant  foods,  644 

potato,  648 

sausage,  626 

vetch,  645 

See    Arsenical   poisoning;    Botulism; 
Carbon   monoxid   poisoning;    In- 
dustrial   poisons;    Lead    poison- 
ing;  Mercurial  poisoning 
Poison  ivy,  1183 
Poison  oak,  1183 
Poisons,  anilin,   1064 

arsenic,  1060 

bacterial,  fish,   635 

benzol,  1064 

carbon  monoxid,  1063 

cause  of  mental  diseases,  342 

cumulative,   1047 

endogenous  and  exogenous,  342 


1262 


INDEX 


Poisons,  in  expired  breath,  738 

hydrogen  sulphid,  1064 

in  industries,  1037 

mercury,  1061 

metallic,  1062 

phosphorus,  1056 

physiological  fish,  635 

for  rats,   276 

for  roaches,  303 

table  of  industrial,  chart  insert,  1046 

See  Poisoning 
Poisonous  gases,   in  air,   721 
Police  powers,  369 

Poliomyelitis.      See   Infantile   paralysis 
Pollack,  59,  60 
Pollak,  147 

Pollock,  Horatio  M.,  339,  341 
Polluted  water,  816 

analysis  of,   869 

bacterial  test  for,  818 

care  of  catchment  areas,  820 

coal-oil  test  for,   817 

definition  of,  790 

fluorescin  test  for,  817 

index  of,  842 

infant  mortality  and,  963 

influence  of,  on  disease,  915 

interstate   pollution   of    streams,    818 

legal  aspects  of,  818 

from  limestone,  810 

saprol  test  for,  817 
Pollution,  of   cisterns,   799 

interstate,  of  streams,  818 

of  lakes,  804 

protection  against,  963 

of  soil,  131,   779 

of  streams,  801,  960 
legal  aspect,  818 

trade  wastes,  974 

of  wells,  812 

See  Polluted  water ;  Stream  pollution 
Polydactylism,  509 
Poncho,  1200 
Ponder,  317 
Ponds,  water  of,  803 
Poor,  44 
Popper,  304 

Polariscope,  milk  sugar  in,  596 
Population,  989 

arithmetical  estimation  of,  992 

distribution  of,  996 

emigration  of,  991 

estimated,  1024 

fluctuations  in,  991 

geometrical  estimation  of,  993 

growth  of,  995 

immigration  of,  991 

land  area  and,  996 


Population,  life  tables,  1032 

mean,  1024 

migration   of,   991,   1027 

nature  of  census  information  of,  990 

natural  increase  in,  992 

source  of   data,  988 

sources  of  error,  in  census,   990 

standard,  1025 

table  of  increase,  991 

See  Birth  rate;  Census;  Infant  Mor- 
tality; Marriage  statistics;  Mor- 
bidity   rates;     Mortality    rates; 
Kegistration 
Pork  tapeworm,   207,   632 
Porosity,  of  soil,  770 
Porter,  955 

Porto  Eican  Anemia  Commission,  131 
Postdiphtheric    paralysis,    169,    421 
Post  exchange,  1192 
Post   mortem   inspection,    615 
Posture,  in  schools,  1085 
Potamon  dehaanii,  207 
Potassium  bichromate,  256 
Potassium  chromate  solution,  848 
Potassium  cyanid,  7,  210,  216 

chart  insert,   1046 
Potassium  nitrate,  548 
Potassium  permanganate,   1155 

disinfectant,  1136 

preservative,  548 

in  water  purification,  906 
Pot  method,  of  fumigation,  1139 
Potable  water,  790 
Potato  poisoning,  648 
Pothier,  236 
Potter's  asthma,   1053 
Potter's  rot,  1053 
Pottery,  manufacture  of,  1052 
Potts,  W.  A.,  335 
Poultry,  drawn,  534 
Powdered  milk,  538 
Powdered  meats,  536 
Prasek,   179 
Pratique,  376 
Pratt,  979 
Precipitinogen,  451 
Precipitins,   450 

tests  for  blood,  452 
for   meat,   454 
Precipitum,  451 

Precipitation  tanks,   sewage,   964 
Pregnancy,      industrial     hygiene     and, 

1042 
Prenatal  infection,  501 
Preparative,  412 
Preparator,  442 
Preparation,  of  food,  550.    See  Food 

of  room,  for  fumigation,  208 


INDEX 


1263 


Preparation,  of  sewage,  for  treatment, 

964 
Presbyterian      Hospital,      Philadelphia, 

typhoid  at,   103 
Preseott,  S.  C,  953 
Prescott-Breed  Test,  milk  in,  591 
Preservation  of  foods,  531 
canning,   540 
cold,   533 
drying,  536 
jellying,  539 
pickling,    538 
preserves,   539 
refrigeration,    542 
salting,  538 
smoking,  539 
sterilization,  by  heat,  542 
Preservatives,  531 
chemical,  542 
arsenic,   549 
benzoate  of  soda,  543 
benzoic   acid,   543 
borax;    boric   acid,   546 
formaldehyd,  544,   547 
gum   benzoin,   543,   544 
hydrocyanic  acid,  543 
hydrofluoric  acid,  549 
hydrogen  peroxid,  549 
lead,  543 
.  in  milk,  568 
potassium  permanganate,  548 
pyroligneous   acid,   542 
salicylic  acid,  544 
sodium  bicarbonate,  549 
sodium  fluorid,  548 
sodium  nitrate,  548 
sulphites,  544,  549 
sulphurous  acid,  549 
cold,   533 
meat,   608 

"natural"  food,  542 
Preserves,  539 
Pressure,  atmospheric,  681 
Prevalence,   of   disease,   1001.     See  un- 
der each  disease 
of  rats,  268 
Preventable  accidents,  70,  1044 
Preventable  blindness,  69 
Prevention,  of  anthrax,  316 
of  beriberi,  652 
of  cancer,  504 
of  cerebrospinal  fever,  199 
of  chancroid,   60 
of  colds,  195 
of  color,  in  water,  828 
of  diphtheria,  166 
of  foot-and-mouth  disease,  319 
fundamentals  of,  1039 


Prevention,  of  glanders,  314 
of  goiter,  920 

of  insect-borne  diseases,   203 
of  leprosy,  329 
of  malaria,  231 

of    malaria    and    yellovp    fever,    con- 
trasted,   244 
of  Malta  fever,  322 
of   measles,    176 
of   mental   deficiency,   337,   341,   345, 

347,  348,  350 
of  odors,  in  water,  827 
of  ophthalmia  neonatorum,   72 
of  pappataci  fever,  261 
of  paresis,  345 
of  pellagra,  657 
of  plague,  285 
of  pneumonia,  190 
of  psychoses,  alcoholic,  341 

traumatic,  348 
of   rabies,   43 
of  sleeping  sickness,  258 
of  tastes,  in  water,  827 
of  typhus  fever,  297 
of  water  pollution,  817 
of  whooping  cough,  185 
of  yellow  fever,  242 
See  Personal  prophylaxis 
Preventive  typhoid  inoculations, 

104 
Preventoria,   158 
Prickly  heat,   1183 
Price,  T.  M.,   218,  547,   1075 
Priestley,  662,  669,  670,  750 
Primrose,   483 
Pringle,    1110 
Prisoners,  number  of,  475 
Privies,  955 

near  dwellings,  976 
ground  water  and,  976 
leaching,  977 
odors  from,  976 
protected,   976 
in  schools,  1088 
screens  for,  976 
soil  of,  976 
and  springs,   816 
ventilation  of,  976 
water-tight  vaults,  976 
near  wells,  976 
Prizer,  175 

Proagglutinoid  zone,  455 
Probability,  law  of,  493 
Proprecipitoid  zone,  451 
Proescher,    45,    47 
Profeta,   324 
Prof  eta's  law,  56,  503 
Prony,   794 


1264 


INDEX 


Propagation,  of  defectives,  472 

of  vaccine  virus,  7 
Prophylaxis,  in  infantile  paralysis,  308 
in  pellagra,  657 
in  scarlet  fever,  182 
in  syphilis,  58 
in  tetanus,   80 
in  venereal  diseases,  61 
See  Personal  prophylaxis 
Proskauer,   1145 
Prosodemic,   368 
Prostatolysin,  445 
Prostitution,  66,  68,  345 
Protargol,    in    ophthalmia   neonatorum, 

78 
Protein  metabolism,  439,  465 
Proteins,  bacterial,  465 
milk,    554 

determination  of,  597 
Protection,  against  pollution,  963 
by  sewage  treatment,  964 
of  water,  by  storage,  819 
Proteolytic  bacteria,  533 

in  milk,  589 
Proteosoma,  228 
Protozoa,   787,  855 

in  sewage,  962 
Protozoon  carriers.     See  Carriers 
Providence,   sewage   treatment  at,  966 
Prowaczek,  69,  260 
Prowazekia  asiatica,   787 
Prowazekia  cruzi,   787 
Prowazekia  urinaria,  787 
Prowazekia  weinbergi,   787 
Pseudomonas  protea,  456,  864 
Psychiatry,   331,   355 
Psychopathic  children,  education  of,  356 
Psychoses,   332 
alcoholic,  338 

prevention  of,  341 
due  to  endogenous  poisons,  342 
erysipelas,  346 
exogenous  poisons,  342 
head  injuries,  347 

prevention   of,   348 
immigration,  353 
influenza,  346 
malarial  fever,  346 
septicemia,  346 
typhoid  fever,  346 
economic  factors  in,  352 
hereditary,  334 

prevention  of,  337 
mental  causes,  348 

prevention,  350 
syphilitic,  343 

prevention   of,   345 
tubercular,  346 


Psychoses.      See    Mental    deficiencies; 

Mental  diseases 
Psychrometer,  694 
Ptomain  poisoning,  528 
poultry  and,   535 

See    Meat    poisoning;     Paratyphoid 
fever 
Ptomains,  517 
in  meat,  621 
in  shellfish,  636 
See  Ptomain  poisoning 
Puberty,  of  school  children,   1097 
Public   Health   Day,   in   Schools,    132 
Pulex,   263 
Pulex  irritans,  263 
Pulex  serraticeps,  263 
Pulicidae,  263 
Pulicke,   118 

Pullman  cars,  disinfection  of,  1170 
Pulp,  vaccine,  5 
Pulverizer,  1147 
Pumpelly,  730 
Puncture,  vaccination  by,  9 
Punnett,  485,   508,   515 
Purification,  of   sewage,   963 
of  water,  878 
by  alum,  908 

by  aluminium  sulphate,  906 
by  Anderson  process,   909 
by  boiling,  882 
chemically,   897 
by  chlorinated  lime,  900 
by  copper  sulphate,  909 
by  distillation,  882 
electrical  methods,  911 
by    evaporation   and    condensation, 

879 
by  filters,  883 
by  iron   sulphate,  908 
in   lakes,    803 
by  metallic  iron,  909 
by  oxidation,  880 
by  ozone,  897 

by  potassium  permanganate,  906 
by   screening,  895 
by  sedimentation,  896 
self-purification   of,    879 
by  storage,  896 
by  sunlight,  881 
by  ultraviolet  rays,  910 
Purjesz,  89 

Pustule-vaccination,  13 
Putnam,  J.  J.,  359 
Putrefaction,  527 
bacteria  in,  1102 
products  of,  529 
in  reservoirs,  806 
sewage,  965,  974 


INDEX 


1265 


Putrescin,  530 

Putrid  milk,  566 

Pycnometer,   599 

Pyemic  conditions,  of  meat,   617 

Pyocyanase,   165 

Pyrethrum,  insecticide,  213,  303 

Pyretophorus,  229 

Pyridin,  210 

chart  insert,   1046 
Pyrolignie  acid,  540 
Pyrosoma  bigeminum,  289 
Pythogenic  theory,  781 

Quackery,   1002 

Qualifications,   of   meat   inspector,   612 

Quales,   89 

Quarantine,  371 

bill  of  health  in,  377 

cholera,  119,  373 

disinfection  of  ships  in,   378 

of  dogs,  in  rabies,  43 

epidemics  and,  367 

equipment  of  station,  377 

interstate,  383 

leprosy,   376 

maritime,   372 

national    vs.    state,    383 

period  of  detention,  372 

preventive,  382 

smallpox,  373 

typhus  fever,  375 

of  vessels,  372 

yellow  fever,  375 

See  also  Isolation 
Quarantine,   plague,   284,   374 
Quarantine   procedures,   376 
Quarantine     officer,     qualifications     of, 

378 
Quarantinable  diseases,  372 
Quartan  fever,  228 
Quartile,  495 
Quasia  infusion,   256 
Quevenne  lactodensimeter,  600 
Quick  lime.     See  Lime 
Quebec,  cholera  in,  112 
Quinin,   use    of,    in   hookwarm    disease, 

130 
Quinin    prophylaxis,     against    malaria, 

233 
Quinolin,  210 
Quint,   1072 

Raber,  B.  F.,  766 
Eabies,  39 

relative  danger  of  bites  in,  42 

dogs  in  epidemics  of,  43 

diagnosis  of,  in  dogs,  52 

entrance  and  exit  of,  41 


Rabies,  immunity  to,  49 

period  of  incubation  in,  40 

prevalence   of,   40 

prevention    of,    43 

Pasteur  treatment,  45 

prophylaxis  in,   43 

treatment  of  wound  in,  44 

virus  of,  fixed,  45 
preparation  of,  45 
street,   45 
viability    of,    42 

See  Pasteur  treatment 
Rabinowitseh,  260,  325 
Race,  death  rates,  1025 
Radiation,    697,    763 
Radioactivity,  708 

Railroad   cars,   disinfection  of,   1169 
cattle  cars,   1170    • 
day  coaches,  1170 
flat   cars,    1169 
freight  cars,  1169 
parlor  ears,  1170 
Rainfall,   amount  of,   798 
Rain  water,  797 

ammonia   in,   840 

amount  of,   798 

analysis  of,  874 

bacteria  in,  800 

cisterns  of,  799 

collection  of,  799 

composition  of,   799 

disposal   of,   957 

evaporation  of,  799 

filters  for,  798 

storage  of,   799 

use  of,  797 

yellow  fever  in,  797 
Rambousek,  J.,  1075 
Ramsey,  665 
Rankine,   792 
Ransom,   429,   631,  633 
Rappaport,  164 
Rarefied  atmosphere,  681 
Rat  tapeworm,  207 
Rates,  population,  992 
Rations,  1189 

emergency,  1192 

field,   1191 

Filipino  scout,  1191 

garrison,  1189 

haversack,  1191 

iron,  1193 

reserve,   1191 

travel,  1191 
Rats,  267 

and  bacterial  rat  viruses,  278 

bites  by,  271 

black,  268,   270 


1266 


INDEX 


Eata,  breeding  of,   268 

brown,   268,   269 

buildings  proof  against,   274 

and  carbon  monoxid,   278 

and  Danysz  virus,  279 

domestic   animals   and,    277 

dysentery  and,  273 

economic  importance  of,  273 

Egyptian,   268,   270 

English,  268,  270 

food  of,  270 

fumigation,  for  destruction  of,   277 

habits   of,    270 

house,  268 

as  intermediate  hosts,  207,  260 

keeping  food  from,  275 

leprosy   and,   273,   325 

migration    of,    269 

Mus   alexandrinus,   268,   270,   274 

Mus  decumanus,  268 

Mus  musculus,  268 

Mus  norvegicus,  268,  273,  274 

Mus  rattus,  268,  269,  270,  272,  274 

Mus  rattus  decumanus,  260 

Mus   rudescens,    260 

natural  enemies  of,  275 

parasites  in,  273 

poisons  for  destruction  of,  276 

prevalence  of,   268 

relation  of  plague  to,  264,  271 

roof,  268,  270 

shooting  of,  277 

suppression  of,  274,  284 

traps  for,   275 

in  trenches,   1204 

and  trichinosis,   273 

and  typhoid  fever,  273 

on  vessels,  270,  278,  374 

Wanderratte,   269 

white,  268 
Raubitschek,   655 
Eauer,  739 

Eauschkinder,  340,  510 
Ravenel,   144,   165 
Eaw  meat,  608 
Rayband,  266 
Eayleigh,  665 

Rays,  ultraviolet,  in  water,  910 
Reaction,   accelerated,  in  vaccinia,   18 

of  milk,  554 

determination  of,  599 

of  water,  831 
Reactions  to   typhoid   inoculations,   105 
Receptors,  410 
Recess,  school,  1085 
Recirculation,  of  air,  748 
Recruiting,  age  of,  1179 

character,   1180 


Recruiting,   chest   measurements,    1180 

general  considerations,  1181 

height,   1180 

mental  condition,  1180 

weight,  1180 
Recruits,   1178 
Red  blood  cells,  681 
Red  lead.     See  Lead  poisoning 
Reductases,  milk,  560 
Reductase  test,  milk,  602 
Reduction  plants,  984 
Reed,  102,  201,  206,  251,  329 
Referee  board,  545 
Refraction,   errors  of,   1073 
Refractometer,  598 

Refrigeration,    effect    of,    on    bacteria, 
949 

as  food  preservative,  535,  542 

of  trichinae,  631 

See  Cold 
Refrigeration  plants,  766 
Refrigerators,  for   cooling  rooms,   766 

household,  534 
Refuse,  981 

incineration  vs.  reduction,  984 

table  of  constituents,  981 

See  Garbage  J; 

Regenerative  burner,  725 
Regiments,   1186 
Registering  thermometers,  688 
Registrar,  988,  997 
Registration,  987 

authority,  996 

burial,  permit  and,   1019 

death  certificate  and,  1019 

fee,  997 

of  mental  defects,  338 

model  bill  for,  996 

model  state  morbidity  law,   1005 

nature  of  information  secured,  997 

responsibility  for,  997 

of  scarlet  fever,  1006 

source  of  data,  997 

undertaker  and,  1020 

in  the  United  States,  996 

use  of,  in  public  health,  1000 

U.  S.  area  of,  for  births,  997 
for  deaths,   1018 

of  venereal  diseases,  65 

See  Birth  rates;  Death  rates;  Infant 
mortality;  Morbidity  rate;  Mor- 
tality rate;   Mortality  statistics; 
Notifiable  diseases 
Regnault  apparatus,  696 
Reiche,   F.,   165 
Reichenbach,   742 
Reincke,  913,  946 
Reinspiration,  of  expired  air,  742 


INDEX 


1267 


Relapsing  fever,  292 

bedbugs  and,   206,  293,  301 

epidemics   of,    292 

and  flies,  206,  248,  254 

immunity  to,  294 

intermediate  hosts  of,   206 

lice  and,  206,  293 
Relation  of  host  and  parasite,  407 
Relative  humidity,   691 
Relief   sewers,   957 
Remsen,  545 
Renk,  692 

Renovating,  corn,  656 
Repin,  918 
Reportable     diseases.       See     Notifiable 

diseases 
Reporting  of  diseases.     See  under  each 

disease 
Reserve   air,    749 
Reserve  corps,  1184 
Reserve  ration,  1191 
Reservoirs,  impounding,  804 
Residual  air,   749 
Residual  humus,    849 
Residual  typhoid  fever,  88,  98 
Resin,  colophony,  214 
Resin-lime  mixture,  220 
Resistance,   389 

lowered,  403 

of  tissues,  399 

See  under  each  disease 
Respiration,  amount  of  air  required  in, 
750 

amount  of  CO2,  749 

dead  space,  750 

factor  of   safety  in,   750 

regulation   of,   670 

tidal  air  in,  749 

vitiation  of  air,  749 

See  also  Air 
Respiratory  capacity,  750 
Retaining  room,  611 
Retinitis  pigmentosa,  509 
Retrovaccination,  8 
Rettger,  718 
Rettger's  method,  718 
Return   cases,    180 
Revaccination,    17,    18 
Reversion,  488 
Rheumatic  tetanus,  79 
Rhinosporidium   seeberi,   787 
Rhus  poisoning,  1183 
Rice,  and  beriberi,  649 
Richards,  659,  678,  766 
Richardson,  104,  307,  737,  1208 
Richet,  457,  459 
Richmond,  measles  in,   173 
Richmond's  slide  rule,  592 


Ricin,  415,  645 

Rickets,  517,  522,  523,  583 

Rieketts,   206,   207,  289,   290,  291,   296, 

469 
Rideal,   1111,   1158 
Rideal-Walker   method,    1111 
Rigor  mortis,  606 
Rimpler,   73 
Rinderpest,  393,  396 
Ringelmann's  chart,  709 
Ringworm,  400,  1095 
Ripe  vaccine  virus,  6,  7 
Rivers,  Dr.,  507 
Rivers,  sewage  in,  956,  961 

as    sewers,    801 

turbidity   of,   830 

(See' Streams 
River  water,  801 

composition   of,    801 

epidemics  due  to,  802 

purity  of,   802 

sample  analyses  of,  875 

typhoid  in,   802 
Roaches,  301 

habits   of,    301 

natural  enemies  of,   302 

poisons  for  destruction  of,  303 

round  worm  in,  303 

structure  of,  301 

suppression  of,  302 

typhoid  and,  303 
Roasting,  of  foods,  552 
Roberts,    1140 
Rock  pile  crematory,  1208 
Rocky  Mountain  spotted   fever,   289 

immunity  to,  291 

intermediate  hosts  of,   206 

prevention  of,   291 

salvarsan  and,  292 

ticks  and,  290 

virus  of,  291 
Rodents,  267 
Rodrigues,  236 
Roger,  124,  301,  454 
Rolander,  326 

Rome,   water   supply   of,   789 
Rommelaere,  118 
Rondelli,  771 
Ronnfeld,  H.,  515 
Rontgen  ray  epithelioma,  504 
Roof  rat,  268,  270 
Rooms,  cooling  of,  765 

disinfection  of,   1166 

overheated,  742 

preparation      of,      for      fumigation, 
208 

temperature  of,  688 

ventilation  of,   754 


1268 


INDEX 


Eooms,  ventilation  of,  and  shape  of,  754 

and  size  of,  754 
Eoosevelt,  545 
Eopy  milk,  567 
Eopke,   1072 

Eosanoff,  A.  J.,  334,  360 
Eoscoe,   705 
Eosenau,  M.  J.,  24,   79,   145,   150,   170, 

172,  206,  236,  251,  278,  280,  305, 

306,  307,  308,  323,  421,  428,  433, 

434,  464,  604,  740 
Eosinase,  421 

.Eoss,  201,  206,  228,  229,  232,  236,  946 
Eost,  330 
Eotch,  562 

Eothenf usser 's  test,  milk  in,  603 
Rotifers,  in  sewage,  962 

in  water,  855,  858 
Eots,   642 
Eouget,   260 
Eoughing  filters,  895 
Eound  worm  in  roaches,  303 
Eoux,   41,   44,   58,   433 
Eowland,  E.   A.,   742 
Eubbish,  981 
See  Eefuse 
Eubella,  174 
Eubeola,  174 
Eubner,   388,   518,   698,   699,   700,    701, 

709 
Eucker,  280 
Eudescens,   260 
Eiidin,    334 
Euediger,  590 
Eiihm,  600,  602 
EuUman,   582 
Eumpel,  118 
Eunge,  1150 

Eural  sewage  disposal,  976 
Euss,  261 
Eussell,    105,    106,   359,    559,   561,   670, 

953,  1137 
Eussula  emetica  Fr.,  646 
Eussula  foetens   (Pers.)   Fr.,  646 
Eussula  quelettii  Fr.,   646 
Eust,  of  plants,  destruction  of,  212 
Eye,  poison  in,   645 

Sabadilla  seeds,  210 

Saccharin,   524 

Sacco,  13 

Sachs,  412,  453,  454 

Sacquepee,   620 

Saggita,   491 

Salembeni,   206,  237 

Saleswomen,   1043 

Salicylic  acid,  42,  539,  544,  547,  548 

Saliva,  161.     (See  also  Sputum 


Salivarius,  253 

Salmon,  331,  359,  360,  361,  619 

Salting,  538 

Salvarsan,  68,  292 

Sambon,  229,  232,  655 

San  Antonio,  health  of  U.  S.  army  at, 

107 
Sanatol,  1153 

Sanatoria,  tuberculosis  in,  152 
Sanchez,  76 
Sand,  on  leprosy,   328 
Sand,  deposits  for  water  in,  809 

sewage  disposal  in,  968 
Sand  filters,  sewage,  968 
Sand  fleas,   1183 
Sand  flies,  1183 
Sandstone,  water  from,  810 
Sandwich  Islands,  measles  in,  174 
Sandwith,  130 
San  Francisco,  typhoid  and  plague  in, 

133 
Sanger,  1061 

Sanitary  analysis,  of  water,  821 
Sanitary   authority,   975 
Sanitary  condition,  of  swimming  pools, 

948 
Sanitary  districts,  370 
Sanitary  habits,  366 
Sanitary  law,  state  authority  in,  369 

federal  authority  in,   369 
Sanitary   legislation,   975 
Sanitary  police,  1197 
Sanitary  standards,  of  milk,  558 
Sanitation,  of  barracks,  1203 

of    camps,    1194 

cooperative,  975 

vs.  hygiene,  389 

keynote  of,  1101 

military,   1194 

of  swimming  pools,  947 

of  trenches,   1204 

See  Military  hygiene 
Saprol,  817 

Saprophytic  organism,  390 
Sarcosporidia,   609 
Sarcinae,  568 
Sarcone,   29 

Sarcoptes  scabiei,  212,  326 
Sausage  poisoning,  626.     See  also  Botu- 
lism 
Savage,   W.   G.,   604,   953 
Sawtchence,  42 
Sawyer,  92,  110,  667 
Scabies,  1183 

of  cattle,  212 

of    school   children,    1095 
Scales,  in  measles,  175 

in  scarlet  fever,  180 


INDEX 


1269 


Sear,  vaccination,   11,   13,   17 
Scarification,  vaccination  by,  10 
Scarlet  fever,  178 

and  flies,  252 

immunity    to,    182 

inoculations,   183 

death  rates  in,  173 

mental   deficiency   in,    346 

milk-borne,   181,  575 

mode  of  transmission   of,   179 

prevention  of  sequelae  in,  183 

return  cases  in,  180 

closing   schools,    182 

specific  prophylaxis  in,   183 

streptococcus  vaccines,   183 

vital  statistics  in,   1006 
Schamberg,      33,      34,      35,      37,      38, 

39 
Schardinger   test,    milk    in,    602 
Schaudinn,   229 
Scheel,    304 

Scheele's  green,  218,  1060 
Scheurer,   198 
Schick,  462 
Schick  reaction,   165 
Schiotz,   165 

Schistosoma  haematobium,   787 
Schistosoma  mansoni,   787 
Schistosomum  japonicum,  207,  787 
Schittenhelm,  459 
Schizotrypanum  cruzi,   260 
Schlapp,  M.  G.,  360 
Schlenker,  546 
Schmeitzner,  Eudolf,   979 
Schmidt,   73,   596 
Schmidt-MuUer  test,  602 
Schmiedeberg,   529,   530,   647 
Schmitt,  326 
Schmutzdecke,  885 
Schneider,   260,   725 
Scholley,   163 
Schonbein,  897 
School  building,  1079 
School  children,  adenoids  of,  1094 

age  of,   1079 

backward  pupils,  1079,  1097 

chorea  of,   1096 

color-blindness  of,  1093 

communicable   diseases   among,   1090, 
1092 

defectives  among,  1097 

discipline  of,   1078 

disease  carriers  among,   1092 
diseases  necessitating  exclusion  among, 
1092 

ears  of,  1093 

epilepsy  among,   1096 

exercises  of,   physical,   1095 


School  children,  eyes  of,  1093 

fatigue  of,  1078 

favus  among,  1095 

height  of,  variations  in,  1082 

home  work  of,  1078 

hygienic  requirements  of,   1089 

hysteria  of,  1096 

impetigo  of,  1095 

incorrigibility   of,    1097 

mental  diseases  of,  1096 

myopia  of,   1082,   1093 

nervous   diseases  of,   1096 

neurasthenic   symptoms  of,   1097 

nose  and  throat  of,  1099 

pediculi  capitis  of,  1095 

posture  of,  1085 

puberty  of,  1097 

ringworm  among,  1095 

scabies  among,  1095 

sexual  perversion  of,   1097 

skin  diseases  of,   1095 

teeth   of,    1094 

vaccination,    1097 
School  rooms,  1080 
School   sessions,    1079 
School   specialists,    medical,    1091 
Schools,   1077 

air  in,  1086 

air  outlets  in,   1087 

attendance   at,    of   well   members   of 
family,  385 

blackboards  in,  1085 

chalk  in,   1085 

cleanliness  in,  1088 

cloak-rooms  in,  1088 

closed  by  epidemics,  1092 
of  cerebrospinal  fever,  200 
of  diphtheria,  168 
of  measles,   178 
of  scarlet  fever,  182 
of    whooping    cough,    186 

color  of  walls  in,  1081 

curtains   of,   1086 

dental  clinics  in,  1094 

desks  and  seats  in,  1082 
Boston,   1084 
Heusinger,   1083 

during  epidemics,   1092 

floor  space  in,  1080 

fresh-air  inlet  in,   1087 

furniture  in,  1081 

heating  of,  1086 

humidity   in,   1087 

janitor  of,  1087 

lighting   of,   1085 

medical  inspection   of,   1089 

medical  inspectors,  duties  of,  1091 

nurse  in,  1090 


1270 


INDEX 


Schools,   playgrounds  of,   1079 
privies  of,  1088 
recess   at,    1085 
stoves  in,   1087 
temperature   of,    1087 
type  for  books  for,   1093 
urinals  in,   1088 
ventilation  of,  755,   1086 
water-closets   in,   1088 
windows  of,   1086 
Schorer,   566,   570 
Schotmiiller,  271,  619,  624 
Schroeder,   572,   581 
Schroter,   1056 
Schuberg,  293,  316 
Schubert,  313 
Schiiflaer,  130 

Schultz,  313,  459,  460,  464,  759 
Schwarz,    667 
Sclerotium,   645 
Scott,  165 

Scoring,   oysters,   637 
Screening,   of   refuge,    982 
of    sewage,    964 
of  water,  895 
Screens,   on   privies,   976 
Scrofula.     See  Tuberculosis 
Scrubbing  filters,  895 
Scurvy,   517,   522,   523,   583 
Scutigera,    256 

and   flies,   256 
Seat,   for   schools,    1082 
Sedgewick,   29,  88,   103,   388,   704,   725, 
767,  796,  913,  914,  926,  937,  946, 
949,   979 
Sedgwick-Eafter  method,  855 
Sedimentation,  of  sewage,  964 

of    water,    896 
Sedimentation   basins,   964 
Segregation,  of  defectives,   472 
heredity  and,  485 
Mendelism  and,  488 
in  tuberculosis,   152 
in  venereal   diseases,   68 
See  Isolation 
Seifeert,  624 
Seippel,  60 
Selection,    483 

Self-purification,   of   streams,   879,  961 
Sellards,  125 
Selmi,  529 
Semple,  42 
Seni,  655 

Senility,  alcoholic,  339 
Sensibilitrice,  442 
Sensitization.     See  Anaphylaxis 
Sensitizer,   412 
Separate  sewage  system,  957 


Sepsin,   529,   530 
Septic   meat,   617 
Septic    sewage,   958 
Septic  sore  throat,  milk  and,  575 
Septic  tanks,  964 
Emscher,  966 
gases  of,  731 
Imhoff,    966 
Septicemia,   psychoses   and,    346 
Septicemic   plague,   280 
Serafini,  1162 
Sergent,   207 
Serum.      See   Antitoxin 
Serum   anaphylaxis,   458 
Serum    antimeningitis,    200 
Serum  disease,   170 
Serum   sickness,   170,   462 
Serum  standardization,  431 
Service,   foreign   inspection,   382 
Settling  tank,   gases  of,   731 

for  sewage,  964 
Sevene,   1059 
Seven-day  fever,  292 
Sewage,  955 

aeration  of,  970 

algae   in,    962 

ammonia,   albuminoid,   959 
free,  959 

analysis  of,  960 

bacteria  in,  959,  962,  964,  972 

of  camps,  976 

Chicago  Drainage  Canal,  803 

chlorin   in,   959 

coagulants  of,  966 

composition  of,  958 

cremation  of,  979 

Crustacea    in,    962 

on  farms,  976 

fats  in,  959 

as  fertilizer,  966 

flies  and,   855,  974 

flow   of,   958 

hydrogen  sulphid  and,  728 

in  lakes,   803 

manurial  value  of,  971 

mineral  matter  in,  959 

mineralization  of,  964 

nitrification  of,  971 

odors   of,   973 

oxidation   of,    969 

oxygen,  consuming  of,  958 

index  of  putrescible  matter,  850 

protozoa  in,  962 

putrefaction   of,   965,   974 

quantity  of,  958 

rotifers  in,  962 

self-purification  of,  961 

septic,  958 


INDEX 


1271 


Sewage,  stale,  958 
streptococci   in,   863 
of    summer    hotels,    976 
tests  for,   973 

total    nitrogen    in,    959 

total   solids  in,   959 

trade   wastes  in,   972 

typhoid    bacilli    in,    94 

volatile  matter   of,   959 

water  carriage  of,  956,  975 
Sewage  disposal,  955 

bacterial  efficiency  in,  972 

from  cesspools,  978 

combined  system  of,  957 

by   dilution,  960 

dry  earth  system,  956 

importance  of  speedy  removal,  955 

rural  problems  of,  976 

separate  system,  957 

in  streams,  960 

use  of  ice  in,  968,  977 

effect  of  wind  on,   974 

See  Cesspools;  Privy;  Sewage  Treat- 
ment;  Stream  Pollution 
Sewage  farms,  of  Berlin  and  Paris,  967 
Sewage  screens,  964 
Sewage  sprinklers,  970 
Sewage   systems,   957 
Sewage  treatment,  963 

activated  sludge   tanks,   971 

bacterial  efficiency  of  processes,   972 

broad  irrigation  of,  966 

chemical  precipitation,  966 

choice  of  methods,  972 

compressed  air  in,   971 

contact  beds,  969 

detritus  tanks,  964 

digestion  tanks  for,  966 

disinfection,   971 

Emscher  tanks,  966 

finishing  processes,  971 

fundamental  principles,  964 

Glasgow,   966 

grit  chambers,  964 

Imhofe  tank,  966 

intermittent   sand    filtration,    968 

London,  966 

management   of   works,   973 

nuisances  caused  by  trade  wastes,  974 

by  ozone,  899 

percentage     removal     of     suspended 
matter,  966 

percolating   filters,   970 

plain   settling   tanks,   965 

preparatory  processes,  964 

protection   due   to,   964 

Providence,  E.   I.,   966 

purification    processes,    966 


Sewage  treatment,   screening,  964 

septic  tanks,  965 

sludge   disposal,    971 

sprinkling   filters,   970 

subsurface  irrigation,  966 

treatment    plants    as    nuisances,    973 

trickling   filters,    970 

vs.    water    filtration,    963 

Worcester,    Mass.,    966 

See  Sewage  Disposal;   Sludge 
Sewer  gas,   729 

accidents    due    to,    730 

bacteria  in,   729 

cause   of    odors    of,    729,    960 

composition   of,    729 
in  settling  tanks,  731 

explosions  due  to,  731 

illustrative  eases  of  death  from,  731 
Sewers,   accidents   in,    730,    733 

air  in,  960 

bacteria  in  air  of,   729 

catch    basins   of,    960 

district,    957 

flushing   of,   960 

house,  957 

intercepting,   817,  957 

lateral,    957 

relief,  957 

rivers  as,   801 

storm,   957 

trunk,  957 

underdrains  in,   957 

ventilation   of,   733,   960 

vents  in,  960 

near  wells,  814 
Sewer  traps,  960 
Sex,    chromosomes,    491 

death   rate   and,   1025-1030 

industrial    hygiene    of,    1042 

population  standard  and,  1026 

life  tables  and,  1032 
Sex  disease,  leprosy,  328 
Sex    hygiene,    61.     See    also    Venereal 

Disease 
Sex  instinct,  350 
Sex-limited   inheritance,    498 
Shakes,   1062 
Shakespeare,    102,    251 
Shardinger's   reagent,   560 
Shaw,  321,  686,  709,  1081,  1084,  1086, 

1097 
Sheehan,  1180 
Sheele,  662 

Sheets,  disinfection,   1174 
Shellac,   526,   549 
Shellfish,    636 

ptomains  and,   636 

typhoid    fever   from,    100 


1272 


INDEX 


Sheppard,  307 

Sherbourne,    water    borne    typhoid,    96 

Sheringham  's   valves,    760 

Shennan,   143 

Sheroux,   327 

Shiek,   169 

Shiga,   122,    123,   282,   945 

Ships,    disinfection    of,    379 

ventilation  of,   755 

See  Vessels 
Shirata,   258 

Shock,   anaphylactic,   459 
Shoes,  1201 
Short-fingeredness,  508 
Shultz,  549 
Shuttleworth,  860 
Side   chain    theory,    408 
Siderosis,   713,    1066 
Sieberman,   1072 
Siemens-Halske,    899 
Siler,  655,  658 
Silicosis,    713 

Silver    acetate,    in    ophthalmia    neona- 
torum,  72 
Silver    nitrate,    in    ophthalmia    neona- 
torum,  72 
Simon,  32 

Simonds,  118,  237,  252,   265,   784 
Simpson,    J.,    883 
Simulium,    653 
Simulium    damnosum,    259 
Simulium  griseicollis,  259 
Simulium    latipes,    259 
Simulium  reptans,  655 
Simulium   wellmanni,   259 
Sjoo,  Axel,   1160 
Skim    milk,    568 
Skimming,    grease,    982,    985 

of   milk,   559,   568 
Skin,   functions   of,   392 
Skin  diseases,  of  school  children,   1095 
Skolfield,  E.  M.,  667 
Slack,   163 
Slaked   lime,    1156 
Slate   blackboards,    1085 
Slatineau,   325 
Slaughter,   emergency,   613 

'  methods  of,   613 
Slaughtering  house,   610 
Sleeping  cars,  disinfection  of,   1170 
Sleeping  sickness,  256 

and  atoxyl,  258 

diagnosis   of,    259 

intermediate    hosts,    206,    256,    260 

prevention  of,  258 
Sliehter,  808 
Slickeos,  1201 
Slide    rule,    Eichmond's,    592 


Slimy   milk,   567 

Slow  sand  filtration,  883,  893 

Slows,   577 

Sludge,   964 

activated  tanks,  971 

in  broad  irrigation,   967 

of  cesspools,  978 
disinfection  of,  979 

of   contact  beds,  969 

cremation  of,  979 

of  digestion  tanks,  966 

disposal  of,  971 

as  fertilizer,  979 

of  grit  chambers,  965 

of  intermittent  sand  filters,  969 

percentage  removal  of,  966 

of   plain   settling   tanks,   965 

of  septic  tanks,  965 

in  subsurface  irrigation,  966 

of   trickling   filters,   970 

utilization   of,   971 
Slye,   Maude,   504 
Smallpox,  1 

and    cowpox,    unity    of,    25 

desquamation  in,  39 

differential  diagnosis  of  chicken  pox 
and,  309 

disinfection  in,   36 

epidemiology  of,   30 

flies  and,   206,   252,   254 

hospitals   for,    36 

immunity  to,   13 

inoculation  in,   27 

modes  of  infection,   30 

mortality    rates,    1018 

multiple  attacks  of,   13 

notification   blank,    1012 

prevalence   of,    29 

quarantine    in,    373 

in  vaccinated  and  unvaccinated,  33 

See  Vaccination 
Smallpox   virus,    resistance   of,    31 
Smillie,  W.  G.,  575 
Smirnoff,    183 
Smith,  80,  739 

Smith,  A.,  341,  619,  668,  708,  840 
Smith,    B.    H.,    549 
Smith,   Claude,   128,  534 
Smith,  G.,   717 
Smith,  H.  E.,  939 
Smith,    Theobald,    179,    201,    206,    229, 

287,  289,  454,  575,  590 
Smoke,    analysis   of,    708 

abatement    of,    709 

of  incinerator,  984 

physiological  effect  of,  709 
Smoking,   of   foods,   539 
Snails,    207 


INDEX 


1273 


Snake  venom,   391 
Snow,  Dr.  John,  116,  925,  926 
Snyder,  560 

Soap,      to      determine      hardness 
836 
tincture  of  green,  264 
Soaps,    germicidal,    1162 

from   reduction   plants,   985 
Social  service,  355 
Sodium  bicarbonate,  549 
Sodium    borate,    255 
Sodium   cacodylate,    292 
Sodium   carbonate,   907 
Sodium  fluorid,  preservative,  548 

for   roaches,   302 
Sodium  nitrate,  548 
Sodium    sulphite,    538 
Soft  water,  834 
Softening,  of  the  brain,  343 
Soil,    767 

adsorption  of,  771 

air  in,   771 

animal   matter   of,   770 

animal  parasites  of,    786 

anthrax  and,   783 

bacteria  in,   769,   778 

B.  welchii  in,   784 

carbon  cycle,   777 

of  cesspools,  978 

cholera  in,    785 

classification  of,  768 

cleanliness  and,   781 

composition   of,   769 

and   dirt,   contrasted,   780 

diseases  of,    782 

Geodesy,  768 

goitre  in,   785 

of  graveyards,   779 

hookworm  disease  in,  130,  786 

influence   of,   upon   health,    782 

malignant   edema   from,    783 

mineral  matter  in,   769 

moisture   in,    772 

law  of,  786 
nitrogen    cycle,    773 
odor   of,    778 
permeability   of,    770 
physical   properties   of,   770 
porosity  of,  770 
privies  in,  976 
relation   of,   to   disease,   778 
in   sewage   sedimentation,   966 
surface   configuration,    768 
temperature  of,   770 
tetanus  from,  782 
tuberculosis  from,   785 
typhoid  fever  from,  94,  102,   784 
vegetable  matter  in,  770 


Soil,  water  in,  772 

water  capacity  of,  770 
Soil  pollution,  779,  979 
of,  hookworms  and,  130 

Solanin,  517,  648 
Soldiers,   diseases  of,   1182 
equipment   of,    1197 
See  Military  Hygiene 
Solids.     See  Total  solids 
Solutol,  1154 
Solveol,   1154 
Sommer,    327 

Sommerfeld,  603,   1049,   1066 
Sommerville,    1158 
Sonden,  672,  673 
Soper,    638,   942 
Sophian,  200 
Sorel,   330,   325 

Sour  milk,   bacteria  of,   565,  566 
Sources,  of  infection,  362 

of  water,   796 
Southard,  E.  E.,  341 
South  African  tick  fever,  297 
South    American    trypanosomiasis,    206 
Soxhlet  method,  595 
Spanish-American  War,  typhoid,   103 
Specificity,  398 

of  anaphylaxis,   460 
in  immunity,  393 
insect  borne  diseases,  202 
Specific   gravity,    of   milk,    600 
Specific  morbidity  rates,   1014 
Spencer,   Herbert,  496 
Sperm,  492 
Sperm   candles,   725 
Sperm  inheritance,   502 
Spermotoxin,    445 
Sphacelinic    acid,    645 
Spieler,   145 
Spina  bifida,  499 
Spirillum    obermeieri,    293 
Spirochaeta  duttoni,   293 
Spirochaeta  pallida,  55,  57 
Spiroschaudinnia"  berbera,   207,   293 
Spiroschaudinnia  carteri,   207,   923 
Spiroschaudinnia  duttoni,  206,  293 
Spiroschaudinnia  marchouxi,   206 
Spiroschaudinnia   recurrentis,    206,    293 
Spitting,   155 
Splenetic  fever,   288 
Spooner,  108 
Sporadic    disease,    367 
Sports,  471,   483 
Spots,  642 

Spotted    fever,    Eocky    Mountain     290 
Spraying,   to    disinfect,   1137 
for  plants,  219 
for  ticks,  288 


1274 


INDEX 


Spring  water,  purity  of,  815 
Spring  and  fall  turnover,  805 
Springfield,  typhoid  in,  101,  103 
Springs,  815 

artesian,  815 

classification   of,   815 

pollution  of,  816 
Sprinkling  filters,  970 
Spurious  takes,  5 
Sputum,    disinfectants,    1173 
corrosive   sublimate,    1173 
See  Feces  disinfection 

disinfection  of,  1105 
by  autoclave,  1174 
in  hospitals,  etc.,  1174 

disposal  of,  tuberculous,  155 

in  water,  817 
Squirrels,   267,   279 

and  plague,   265 

suppression  of,  280 
Squirrel   flea,   263,   265 
Stable,  disinfection  of,  1168 
Stable   fly,    307.      See   Stomoxys   Calci- 

trans 
Stack  burner,  for  sulphur,  1141 
Stagnation,  of  water,  805 
Standard,    of   living,    994 

of  milk,  558 
Standard  death  certificate,   1019 
Standard   deviation,   495 
Standard  lime-water,   678 
Standard    methods,    of    water    analysis, 

821 
Standardization,  of  antitoxin,  431 

of  bacterial  vaccines,  398 

of   disinfectants,   1109 

of   tetanus   antitoxin,  433 
Stanton,    651 
Staphylococci,  194 
Starvation,   521 
State   authority,   369 
State  model  morbidity  law,   1005 
State  morbidity   rates,   1008 
State  notifiable  diseases,   1004,  1006 
State   registration   laws,    1005 
States,   registration   area   of,   1018 
Stationary   air,    749 
Statistical  methods,  493 
Statistics,    493 

of  mental  diseases,  332 

See  Vital  statistics 
Steam,   to    disinfect  wells,    815 

as   disinfectant,   1122 

in  preparation  of  food,  551      ' 
Steam  disinfecting  chamber,  1125 
Steam  heating,  765 
Steam  pressure  recorders,   1131 
Steapsin,   421 


Stedman,    H.    E.,    361 
Steel,  on   surra,   206,   260 
Steel,  chart  insert,   1046 
Steerage,  ventilation  of,  754 
Stegomyia  calopus,  206,   221,  236,   239, 

375,  797,  947 
Stegomyia  fasciatus,  236 
Stephens,  206,  257 
Stephenson,  74 
Sterilization,  1099 

of  defectives,  474 

fractional,  food,  540 

due  to  gonorrhea,  59 

of    wells,    815 
Sterilizers,    Arnold    steam,    1123 

autoclave,  1124 

Bramhall-Deane,  1124 

dry    wall,    981 

Koch  steamer,  1124 

steam    chambers    of,    1125 
Stern,  452 

Sternberg,  191,  243,  1155,  1157 
Sternberg   method,    1110 
Stevens,   E.  M.,   1098 
Stevens '   ventilator,   760 
Stewart-Slack  test,   591 
Stewing,  of  foods,  552 
Steyer,    683 

St.  Gothard  's  tunnel,  relation  to  hook- 
worm disease,  126 
Sticker,   327,   328 
Sticky  fly-paper,   214 
Stigmata,  of  degeneration,  471 
Stiles,  126,  127,  130,  131,  280,  639,  788 
Still,   143 
Stimson,   279 
Stitt,   246 

Stomoxys  calcitrans,  206,  248,  250,  251, 
269 

anthrax  and,  316 

pellagra   and,   653,   659 

poliomyelitis  and,   307 
Stone,   219 
Storage,   of  water,   779,   804,   819,   875, 

896 
Storch,   601 

Storch  test,  milk  in,  603 
Store,  252 
Storm  sewers,  957 
Stoves,  Franklin,  764 
Stoves,  in  schools,  1087 
Stramonium  leaves,  210 
Straiibli,   629 

Straus   Home   Pasteurizer,   585 
Strauss,  I.,  307 

Strauss  reaction,   in   glanders,   312 
Stream  pollution,  801,  960 

biological   equilibrium,   962 


INDEX 


1275 


Stream  pollution,   dissolved   oxygen,   in 
water,   961 

hygienic    aspects    of,    962 

interstate,   818 

remedies  for,  976 

sewage  disposal  of,  by  dilution,  960 

by  trade  wastes,  974 
Streams,       self -purification      of,       879. 
961 

sewage  in,  956,  961 

See  Eivers 
Street   dust,   714 
Street  sweepings,  981 
Street  virus,  45 

Streptobacillus,    of    Ducrey,    60 
Streptococci,  in  common  colds,   194 

in  cerebrospinal  fever,  197 

in  meat,  626 

in  milk,  576,  590 

in  sewage,  863 
Streptococcus,   Beta   type,   575,   590 
Streptococcus  conglomeratus,   179 
Streptococcus   equinus   fecalis,   253 
Streptococcus    lactis,    566,    590 
Streptococcus  mucous,   189 
Streptococcus     pyogenes     aureus,     165, 

590,  863 
Streptococcus  scarlatinae,  179 
Streptothrix   muris   ratti,    271 
Stripping,  of  water,  806 

of    white    lead,    1052 
Strippings,  of  milk,  556 
Strong,   282,    653 
Strongyloides  stercoralis,  127,  788 
Struma,  916 
Strumpf,    1047 

St.    Vitus 's   dance.      See   Chorea 
Strychnin,   276 
Stiller,   1050 
Stynis,    899 

Substance   sensibilitrice,  439,  442 
Subsurface    irrigation,    966 
Suicide,   849 
Sulphanilic    acid,    843 
Sulphates,    in    water,    834 
Sulphur,    flowers   of,    211 

for    roaches,    303 

for   ticks,   287 
Sulphur  chlorid,  chart  index,  1046 
Sulphur   dioxid,   211 

in  air,   729 

bedbugs   and,   300 

as  disinfectant,  1132 

fleas   and,    264 

industrial   poison,    chart  insert,    1046 

as   an   insecticide,    210,    1138 

rats   and,   277 

roaches  and,  302 


Sulphur    dioxid    fumigation,    1138 

amount   of    sulphur   necessary,    1139, 
1141 

Clayton  furnace,  1144 

Kinyoun-Francis  furnace,   1143 

liquid   sulphur   dioxid,   1141 

pot   method,    1139 

stack  burner  for,  1141 

sulphur    furnace,    1142 
Sulphur  dips,   212 
Sulphur    furnaces,    1142 
Sulphur    ointment,    212 
Sulphuretted    hydrogen,    704 

chart   insert,   1046 
Sulphuric   acid,   to   disinfect  wells,   814 

industrial    poison,    chart   index,    1046 

in  smoke,  709 
Sulphurous    acid,    549 

chart    index,    1046,    1141 
Sunburn,  706 
Sunlight,    as    disinfectant,    1101,    1119 

physiological   effect   of,    706 

effect  on  water,   881 
Supplemental  air,   749 
Supplies,    double   water,    796 
Suppression,   of   bedbugs,   300 

of    flies,    254 

of   lice,   295 

of   mosquitoes,   223 

of  rats,   274 

of   roaches,   302 

of  ticks,   288 
Surface  waters,   800.     See  water 
Surgeon-general's  library,   1188 
Surgery,    defectives,    473 
Surra,   206,   260 
Survival   of   fittest,   482 
Susceptibility,    394 
Sutton,    245 
Sweeping,   dry,    714 
Swimming    pools,    947 

diseases   contracted   in,   948 

hygienic    conditions    of,    948 

sanitation  of,  947 
Swine,  as  intermediate  hosts,  207 
Swine    plague,    617,    619 
Swithinbank,   575,   581,    604 
Syphilis,    54 

and    calomel    ointment,    58,    67 

consequences  of,  55 

economic  aspects  of,  55 

hereditary   transmission    of,    502 

immunity    to,    56 

life    insurance    and,    57 

marriage    and,    345 

medical  prophylaxis  in,   67 

mental  deficiency   and,   343,   344 

modes    of    transmission    of,    56    • 


1276 


INDEX 


Syphilis,  prevalence  of,  57 

prophylaxis    of,    58 

salvarsan,  68 

Spirochaeta  pallida,  55 

Treponema  pallidum,  55 

and   vaccination,    22 

Wassermann  reaction  in,  345,  446 
Symbiosis,    527,    1101 
Symmers,    144 
Syncytiolysin,   445 
Synura,    585 
Syrups,  539 

Tabaninae,    206 
Tabanus,    248 
Tabanus  striatus,  316 
Tabanus    tropicus,    260 
Tabardillo,   289,   296 
Table,   amounts   of   water   used,   793 
animal    parasites    of    man,    788 
antiseptic  values,    1163 
birth  rates  in  countries,   1000 
cities    using    mechanical    filters,    894 
cities  using  slow  sand  filtration,  891 
colon-typhoid   group,    621 
constituents  of   city   refuse,   981 
death   rate,   by   ages,    1025,    1029 
in   certain    countries,    1028 
marital  status,   1027 
by  sex,  1029 
diagnostic  errors,  in  mortality  rates, 

1021 
diseases    carried    by    flies,    206,    254 
dust  in  air,   of   factories,    1065 
expectation    of    life,    in    N.    Y.    City, 

1033 
germicides,   commercial,   1118 
hardness  of  water,  836 
industrial  poisons,  chart  insert,  1046 
infant    mortality,    in    certain    coun- 
tries, 1031 
of  insecticides,  210 
intermediate    hosts,    207 
life,  1032 

of   New   York    City,    1033 
meat  condemnation,   618 
New  York  City   death  rate,   1030 
notifiable    diseases,    1004,    1006 

occupational,   1005,   1007 
percentage  correct  diagnosis,  1021 
population  increase,   991 
sex  factor,  in  New  York  City  death 

rates,  1030 
suspended      matter      removed      from 
sewage,    966 
Taenia  africana,  788 
Taenia  bremneri,   788 
Taenia  confusa,   788 


Taenia  echinococcus,  633 

Taenia  hominis,   788 

Taenia  medio-canellata,  633 

Taenia   philippina,   788 

Taenia  saginata,  207,  533,  633,  788 

Taenia  solium,  207,  533,  632,  788 

Takaki,   429,   649 

Talbot,   468 

Tallow  candles,   725 

Talsuist,   636 

Tanks,   activated  sludge,  971 

digestion,  966 

Emscher,  966 

detritus,   964 

Imhoff,   965 

plain    settling,    965 

refuse,  982 

screening  of,  226 

septic,   965 
Tankage,  dried,  986 

fat  in,  985 

fertilizer,  985 

of  reduction  plants,  985 
Tank  room,   611 
Tannery    wastes,    728 
Tapeworms,   550 

beef,  207 

dwarf,    207 

fish,    207,    635 

measley,    632 

meat,   617 

pork,    207,    632 

rat,  207 

See  Taenia 
Tar,    chart    insert,    1046 
Tar   camphor,   1154 
Tarbagan,  265 
Tarbardillo,    296 
Taste   of   water,   823 

due  to  algae,  827 

due  to  organisms,  826 
Taussig,  59,   261 
Taute,  257 
Taylor,  545 
Teague,   281 
Teakwood   dust,   1070 
Technic,   carbolic   coefficient,    1114 
Teeth,    of    school    children,    1094 
Teleky,  1050 
Temperance,    341 
Temperature,  of  air,  687 

bacteria,  effect  on,  550 

carbolic   coefficient,   1114 

disinfection,   1106 

extremes  of,  687 

food    preservation    and,    533 

physiological   significance   of,   697 

refrigerator  and,  533 


INDEX 


1277 


Temperature,    relation    of,    to    humid- 
ity, 697 
for  school-room,  1087 
of   soil,    770 
in   textile   mills,    1069 
ventilation,  effect  on,  688 
Temporary  carrier,  365 
Temporary  hardness,  834 
Tendency,   to   disease,   transmission   of, 

501 
Terman,  L.  M.,  361 
Terminal   fumigation,   in    measles,    178 

in    scarlet   fever,    183 
Tests,    for    blood,    452 
Terni,  282 
Tertian  fever,  228 
Terzi,    229 

Test,  diphtheria  antitoxin,  431 
hemolytic,  444 
for  meat,   607 
spoiled  meat,  608 
of  sewage,  973 
tetanus  antitoxin,  434 
Tetanaspasmin,  426,  427 
Tetanin,   427 
Tetanolysin,   426,  427 
Tetano toxin,   427 
Tetanus,  75 
etiology  of,  75 
idiopathic,  79 
incubation   period   of,    79 
treatment   of   wounds   in,   80 
prophylaxis    of,    80 
resistance   of  bacillus  in,   79 
rheumatic,   79 
in    soil,    769,    782 
specific  prophylaxis  of,   81 
and  vaccination,   22 
viability   of   bacillus,   80 
and   wound   complications,    76 
Tetanus  antitoxin,   81,   418,   430 
unit,    434 

standardization  of,  433 
Tetanus   bacillus,    75,   76,   77 
Tetanus  carriers,   76 
Tetanus  dolorosus,   429 
Tetanus  toxin,  417 
composition    of,    426 
in  diphtheria  serum,  428 
in   horses,    428 
mode  of  action,  429 
by  mouth,   427 
preparation   of,   428 
toxicity    of,    426 
Tetrachlorethane,    297 
Tetramitus   mesnili,   787 
Tetravaccine,  397 
Tetrodon,  635 


Tents,    1197 
Texas  fever,  288 
immunity  to,   396 
intermediate   hosts,    206 
malaria  and,   228 
Texas    fever    tick,    289 
Textile  industries,  digging,  1069 
humidity   in,   1068 
hygiene  of,  1068 
temperature  in,   1069 
Thackrah,   727 
Thamehayn,  51 
Thayer,  199 
Theiler,  260 

Theories,   of  immunity,   408 
Thermal    circulation,    758 
Thermal    death    points,    milk    enzymes, 

561 
Thermal  unit,   763 
Thermometers,  109,  688 

automatic,    1129 

disinfection  of,   1176 
wet-bulb,    698 
Thiem,   808 
Thompson,  20,  265,  490,  515,  518,  519, 

605,  655,  658,  659,  1075 
Thorn,  511 
Thorpe,   1053,    1057 
Thread  method,   disinfectants,   1109 
Threadworm,  246 
Three-day  fever,   206 
Thresh,    638,    792,    851,   910,   953 
Throat,    and   nose,    of    school   children, 

1094 
Thro,    308 
Thrushfield,  160 
Thurston,  E.  H.,  518 
Thwaites,  W.,  728 
Thymoe,   130 
Tibbies,    659 

Tick  fever,  206,  288,  292 
Ticks,   287 

African  tick  fever,  206 

Amblyomma  americanus  linnaeus,  291 

and  arsenical  dips,  288 

Boophilus  bovis,   289 

canine    babesiasis,    206 

cattle,   289 

control   of,   288 

dipping,    288 

diseases    carried    by,    288 

Dermacentor  marginatus,  291 

Dermacentor  oceidentalis,  290 

Dermacentor  variabilis,   291 

Dermacentor    venustus,    290,    291 

eradication  of,  292 

life  cycle  of,  287 

Margaropus   annulatus,   289 


1278 


INDEX 


Ornithodorus  moubata,  293 

and  relapsing  fever,  206 

Eocky   Mountain    spotted   fever   and, 

206,   290 
spraying,   288 
and  sulphur,  212,  287 
Texas    fever,    289 
Tidal   air,    749 
Tidswell,   325 
Tieche,  18 
Timoni,   28 

Tin,   for   canning  foods,   541 
Tincture,  of  green  soap,  264 
Tindal,   899 
Tizzoni,  46,  252,  433 
Toadstools,   646 
Tobin's   tubes,    760 
Todd,  122,  162,  206,  256,  257,  259,  260, 

293 
Toledo,   76 
Tolerance,  390 
Tollwuth,  39 
Toluen,  544 
Tonney,   572 
Tonsilitis,  in  milk,  575 
Tordieu,  51 
Tornell,  V.,  1160 
Torole,   468 
Torrey,  253 

Total   nitrogen,   in    sewage,   959 
Total  solids,  of  milk,  558 
determination   of,   592 
State    requirements,    558 
in  sewage,  959 
in   water,   833 
Toxalbumin,  427 
Toxascaris  canis,  788 
Toxicogenic,   628 
Toxin,  410,  414 
botulismus,    627 
dysentery,  122 
mussel  poisoning,   639 
noxe,   655 
paratyphoid,  625 
solanin,   648 
tetanus,  426 
Toxine,   and  toxin,  418 

definition  of,   530 
Toxins,  414 
amanita,   646 
definition  of,   414 
in  ergot,   645 
fish,   635 
incubation,  416 
kinds  of,  414 
lesions,  416 
by   mouth,   415 
muscarine,    647 


Toxoids,  410 
Toxon,  170 
Toxophore,  410 
Trachoma,   69 
Trade   wastes,    972 
acid  iron,  975 
as   nuisances,    974 
Trade  winds,   686 
Transference,  biologic,  201 

mechanical,    201 
Transmission,  congenital,  501 
hereditary,    of    disease,    498 
by   insects,   201 
tendency   to    disease,    501 
See  Mode  of  transmission 
Traps,   for   rats,   275 

in  sewers,  960 
Trash,   181 
Trask,  John  W.,  987 
Traumatism,  psychoses  and,  347 
Travel  ration,  1191 
Travois,    1189 

Tredgold,  335,  336,  340,  344,  345 
Trematoda,    787 
Trembles,  577 
Trenches,    1204 
Trenchinosis,   630 

Treponema  pallidum,   55,   344,  502 
Trichina   spiralis,   629 
effect  of  pickling,  538 
larvae,    629 

meat  inspection   and,   608 
refrigeration,   533,   631 
thermal  death  point  of,  550 
viability,    631 
Trichinella     spiralis,     207,     273,     400, 

629 
Trichiniasis,    629 
Trichinosis,    629 

cooked  meat  and,   630 
epidemics  of,  630 
prevention    of,    630 
in  rats,  273 
Trichomonas    hominis,    787 
Trichomonas   dysenteriae,    787 
Trichomonas    pulmonalis,    787 
Trichomonas  vaginalis,  787 
Trichostrongylus   colubriformis,   788 
Trichostrongylus   probulurus,   788 
Trichostrongylus  vitrinus,  788 
Trichuris   trichura,    787,   947 
Trickling    filters,    970 
Tricresol,  264,  422,   11G2 
Tridontophorus    diminutus,    788 
Trillat,   817 
Trioxymethylene,   1133 
Trismus    neonatorum,    77 
Tropical   malaria,   228 


INDEX 


127!l 


Tropical  sore,  and  flies,  254 

Trouessart,   267 

Troughs,    disinfection    of,    1169 
Trout,    goiter    in,    918 
Trudeau,    149 
Trunk    sewers,    957 
Trypanosoma    brucei,    206,    260 
Trypanosoma   castellani,    260 
Trypanosoma    cruzi,    206 
Trypanosoma    dimorphon,    260 
Trypanosoma  equinum,  260 
Trypanosoma   equiperdum,   260 
Trypanosoma   evansi,    206,    260 
Trypanosoma  gambiense,  206,  256,  260, 

273 
Trypanosoma  grussei,  256 
Trypanosoma  lewisi,   256,   260 
Trypanosoma  rhodiense,   206,   257 
Trypanosoma   theileri,   260 
Trypanosoma   ugandense,    260 
Trypanosomes,   kala-azar   and,   261 

table   of,    260 
Trypanosomiasis,    206 
Tryptophane,  324  ' 

Tschermak,  486 
Tsistowitch,  451 
Tsetse  fly,  256 

Tubercle  bacilli,  in  milk,  590 
Tubercles,  in  water-pipes,  852 
Tuberculin,    148,    149 

leprosy   and,    330 

reactions  of,  4o6 

use  of,   467 
Tuberculosis,    134 

aerogenic   infection,    141 

air-boone,  141 

anaphylaxis,  466 

antiformin,    action    of,    1160 

associations,   153 

avian,    136 

Bang   method,    157 

bedbugs  and,   301 

blindness  in,  69 

bovine,    in     man,     136 
prevention    of,    157 

campaign    against,    158 

care  of,  in  the  home,  156 

in  children,  156 

contact  infection,  146 

Cornet-Koch   theory,    141 

decline   of,   151 

early  diagnosis  of,   155 

disinfection  in,  155 

droplet    infection    in,    142 

fish,  136 

flies,    146,    251 

hereditary   transmission   of,   149 

housing  of,  156 


Tuberculosis,    human    and    bovine,    135 

immunity   to,    147 

industrial    conditions    of,    156 

industrial    insurance   in,    158 

industrial   prevalence    of,    1074 

ingestion  infection  of,  143 

insanity    and,    346 

lead  poisoning  and,  1050 

in    meat,    616 

in    miners,    1071 

in   milk,   139,   572 

modes  of  infection  of,   141,  502 

notification    of,    154 

personal   prophylaxis   in,    153 

prevention   of,   150 

resistance  of  virus  in,   150 

segregation  in,  152 

and   soil,    785 

sputum,   disposal   of,   155 

summary,    158 

tuberculin,    148,    149 

and  vaccination,   22 

value    of    reporting,    1014 

in    water,    146,    914 
Tuberculosis    dispensaries,    153 
Tuberculosis  education,   154 
Tuberculosis   sanatoria,   152 
Tunnieliflfe,    546 
Turbid    water,    915 
Turbidimeter,  831 
Turbidity,   of   rivers,   830 

standard   of,   831 

of  water,  828 
Turmeric,   525 
Turneaure,    F.    E.,    953 
Turner,  Sir  George,  329 
Turnover,    805 
Turpentine,    insecticide,    210,    295,    297 

industrial   poison,   chart  insert,   1046 
Tyler,  654 
Tyndall,    719 

Type,   for   schoolbooks,    1093 
Typhoid  bacilli,  90.     See  also  B.  typho- 
sus 
Typhoid  fever,   83 

at  Ashland,  940 

attitude  toward,  83 

bacillus  carriers,   92 

blood  cultures,  89 

Brill's  disease  and,  296 

at  Butler,  942 

at  Chicago,  944 

contact  infection,    103 

death  rates,  85-88,   1008,   1018 
European,  963 
due    to    water,    933-935 

diagnosis   of,    89 

disinfection  of  excreta,   109 


1280 


INDEX 


Typhoid  fever,   dust,   102 
epidemic,  at  Allegheny,  943 

at   Lawrence,'  943 

at  Lowell,   943 

at  Pittsburgh,  943 
feces  and,  90 

flies  and,  101,   206,  251,   254 
fomites,  102 
fruits  and,   101 
from  ground  water,   811 
and  ice,   98,   952 
immunity  in,   296 
influence  of  water,  95,   864,   932 

on  death  rate,  915,  933-935 
at   Ithaca,   942 
at  Lausen,  933 
management  of  case  of,   108 
at  Mankato,   Minn.,  941 
milk-borne,   85,  98,  575 
mode  of  entrance  and  exit,  89 
modes  of   spread,   94 
morbidity  rate,   1008 
in    mussels,    100 
at  New  Haven,  Conn.,  939 
in   oysters,    100,   637 
paratyphoid  and,  623 
personal  prophylaxis  in,  110,  298 
prevalence  of,  84 
at  Plymouth,  Penn.,  938 
preventive   inoculations    against,    104 
psychoses    and,    346 
rats    and,    273 
residual,   88 
residual  rates,  98 
resistance  of  the  virus,  93 
in  river  water,   802 
roaches  and,  303 
shellfish  and,  100 
in   soil,    102,    784 

in  Spanish- American   War,    103,   251 
sumjnary  of,  110 
in  United  States  Army,  106 
in  United  States  Navy,   107 
vegetables  and,  101,  644 
viability    in   water,    963 
in  water,  932 

longevity  of  bacilli,   962 
water-borne  epidemics  of,  94,  923 

characteristics  of,  96 

See  Typhoid  epidemics 
Widal  reaction  in,  93 
See  Vaccines 
Typhoid  inoculations,   in  maneuver   di- 
vision,  107 
summary  of,  108 
Typhoid   vaccine,    negative   phase,    106 
Typhus  fever,  295 
and  fleas,  263 


Typhus   fever,   intermediate   hosts,   207 

lice   and,   207,   295 

in  Mexico,  289 

mortality  rates  in,  1018 

prevention   of,   297 

quarantine  in,   375 

virus  of,   296 
Tyrotoxicon,  529 
Tyzzer,  25,  32,  504 

Udder,    inflammation    of,    562 
Uhlenhuth,  452,  461 
Ultramicroscopic  virus,  foot-and-mouth- 
disease,  318 

poliomyelitis,   304 
Ultraviolet  rays,  910 

disinfectant,   1119 

use   in   water   purification,   910 
Uncinariasis,      120.       See    also     Hook- 
worm  Disease 
Uncinariinae,  127 
Underdrains,  957,  968 
Undertaker,  registration  and  the,  1020 
Underwear,    1201 
Uniformity    coefficient,    886 
Unit,    diphtheria    antitoxin,    431 

tetanus    antitoxin,    434 

thermal,  763 
Unit   characters,    485,   488 
United   States   Army,    typhoid    in,    107 
United  States  death  registration,   1018 
United    States    Meat    Inspection    Law, 

614 
United    States   Navy,    typhoid    in,    107 
United  States  morbidity  statistics,  1003 
United  States  notifiable  diseases,  1004, 

1006 
United  States  notification   blank,   1012 
United   States   registration    area,    1018 

for  births,   997 
Urea,  in  sewage,  959 
Urease,    421 

Urinals,    in    schools,    1088 
Urine,  in  water,   817 
Uroglena,    826,    858 
Urotropin,    110,    200,    292 
Vacca,    3 
Vaccination,   1 

altered   reactions,    18 

anaphylaxis,   relation  to,  467 

areola,  4,  8,  12,  13 

arm-to-arm,  4 

auto-,   22 

birth  rates  in,  value  of,  1000 

for   ehiekenpox,   310 

claims  for,   20 

compulsory,    25 

course  of  eruption  in,  12 


INDEX 


1281 


Vaccination,  dangers  and  complications 
of,   21 

with   dry   points,    6 

of  exposed  persons,   20 

and   foot-and-mouth   disease,    24 

generalized,   22 

historical   note,   2 

impetigo   contagiosa   and,   22 

incision  for,  9,   10 

indices   of   a   successful   take    in,    11 

leprosy  and,  22 

methods  of,  9 

notification   of,    1012 

number    of    incisions    in,    10 

the  operation  of,  11 

puncture  in,  9 

pustule  of,   13 

result  of,   in   Germany,   33 

revaecination,    17,    18 

scar   of,    11,    13,    17 

scarification,  10 

in    schools,    1097 

spurious  takes,  5 

symptoms   in,    13 

syphilis  and,  22 

tetanus  and,  22 

tuberculosis  and,  22 

typhoid   and.      See    Typhoid 

vesicle  of,   12 

wound    infections,    22 
Vaccine,   4,    396 
Vaccine  virus,  4 

bacteria  in,   7 

bovine,    5 

carbolic   acid,    7 

chlorobutanol,   7 

chloroform,  7 

definition   of,   4,   396 

dry,  5 

foot-and-mouth   disease,  318 

fresh,  5 

green,  6 

government  control  of,  24 

glycerinated,  5 

liuman,  4 

potassium  cyanid,  7 

propagation  of,  8     - 

ripe,   6 

seed,    7 
'  vaccine  lymph,  5 

vaccine  pulp,  5 
Vaccines,    bacterial,    397 

cholera  and,  118 

meningococcus  and,  200 

plague    and,    282 
polyvalent,   397 

preparation   of,   397 

sensitized,  397 
43 


A^accines,  for  scarlet  fever,  183 

standardization  of,  398 

tetanus   and,    78 

typhoid.     Sec  Typhoid 

whooping   cough    and,    186 
Vaccinia,  3,  4,  8,  12,  27,  318 
Vacuum  system,  762 
Vaillard,  79 
Vallee,    144 
Valentin,  737 
Valerio,    206 
Van  De  Velde,   561 
Van   Gehuchten,   53 
Van  Gieson,   52,   53 
Van  Slyke,  L.  L.,  554 
Vapor   tension,   690 
Variability,  coefficient  of,  496 
Variate,   495 
Variation,  481 

amount  of,  495 
Varicella,  309 
Variola,  3,  20 
Variola  inoculata,  27 
Variola  vera,  27 
Varioloid,    20 
Varro,    229 
Vas  deferens,  473 
Vasectomy,    473 
Vaughan,  102,  171,  251,  323,  413,  528, 

529,  530,   546,   1009 
Vedder,  E.  B.,  124,  649 
Veenboer   546 

Vegetable  dyes,  in  food,  525 
Vegetable  matter,  in  soil,  770 
Vegetables,    644 

cooking  of,  551 

as  disease  carriers,   644 

hookworm    and,    132 

poisoning  from,  644.     See  Foods 

typhoid   and,    101 
Veillon,    76 

Velocity,  air  currents,  686 
Venal)Ie,    W.    M.,    986 
Venereal  diseases,  53 

alcohol  and,   65 

attitude   towards,   62 

continence   in,   65 

education  in,  63 

medical  prophylaxis  in,   67 

personal    hygiene    in,    66 

prevalence  of,   61 

prophylaxis  in,  61 

prostitution    and,    66 

registration  of,  65 

segregation  in,  68 

See  Chancroid;   Gonorrhea;   Ophthal- 
mia neonatorum;  Syphilis 
Vents,   sewer,  960 


1282 


INDEX 


Ventilation,   746 
alveolar,    750 
air  ducts  in,   756 
air  needed  per  hour,  751 
air  washing,  748 
aspiration,  758 
of  bakery,  755 
of  barracks,   754 
blowers   in,    762 
COj,   effects   of    increased,    737 

expired  per  hour,   752 
computations    of    efficiency,    754 
cooling,    765 
of   cowsheds,    755 
dead-space   air,    750 
dust,    1067 
exhaust    system,    762 
external,   758 
factor    of    safety   in,    750 
of  factories,   755 
fans  in,   762 
floor-space,    756 
of   hospitals,    754 
effect   of   humidity,    693 
inlets,    756 

in  industrial  hygiene,  1045 
of  lodging  houses,  755 
of  match  factory,  1057 
mechanical,  762 
minimum  space,  table,  755 
natural,   758 
odors,   704 
outlets,    756 

Qxygen,  effects  of   diminished,   737 
o:^one,  uses  of,  666 
perflation,    758 
plenum  system,   762 
of  privies,  976 
purpose   of,   746 
recirculation,   748 
respiratory   vitiation,    749 
rooms,    size    and    shape,    754 
of    sewers,    733,    960 
of    schools,    755,    1086 
of  ships,   755 
standards  of  purity,  753 
summary   of,   744 
temperature,   effect  of,  688 
vacuum  system,   762 
vitiation  of   air,   751 
volume    of    air    needed,    753 
through  walls,   etc.,    759 
by   windows,    1087 
See  also  Air 
Ventilators,    756 

Ellison's  bricks,  760 
Grid,    761 
Hinckes-Bird,    761 


Ventilators,   Hopper,   761 
Louvred    outlets,    761 
McKinnell's,    761 
Sheringham,    760 
Stevens,    761 
Tobin's  tubes,  760 
window,    760 
Verco,  501 
Verhocff,   1121 
Vermifuges,    130 
Vesicle,  in  vaccination,   12 
Vessels,  ballast,  382 
disinfection    of,    379 
fumigation  of,  for  yellow  fever,  375 
plague  and,   374 
in  quarantine,   372 
rats  on,  270 
water    ballast,    373 
See    Ships 
Vetch    poisoning,    645 
Viability,    typhoid    bacilli,    94 
Vibrio    cholerae,    113,    925.      See    also 

Cholera  vibrio 
Vibrion  septique,  783 
Vienna,  water-borne  typhoid  in,  97 
Vieusseux,    197 
Vieth,   601 
Villamin,    135 
Vincent,   79 

Vinegar,    for    pickling,    538 
Vinegar  extract,  of  spices,  545 
Virulent  strains,  of  diphtheria,  163 
Virus,   Danysz,   279 
filterable,   6 

foot-and-mouth    disease,    318 
fixed,    45 

immunity  and,  396 
in  infantile   paralysis,   304 
rat,   278 

resistance  of,  42 
in   trachoma,    69 
in  typhoid,  93 
ultramicroseopic,   318 
of  yellow  fever,  237 
See    also    Vaccine    Virus;     Vaccines, 
bacterial 
Vital  capacity,  750 
Vital  statistics,  987 

causative  factors,  importance  of,  1016 
constituents  of,  987 
definition,  988 
derivation  of,  987 
development  of,   988 
diagnostician,  value  of,  1011 
disease,  influence  of,  1001 
emigration,  988 
enumeration,  987 
fertility   of   race,   999 


INDEX 


1283 


Vital    statistics,    hospital,    1015 

illegitimacy,  999 

immigration,  988 

industrial  diseases,   1036 

of  insane,  1015 

insurance    records,    1015 

laboratory  value  of,  1010 

life  tables,   1032 

of  mental  defectives,  1015 

origin    of,    988 

of  outbreaks,   1017 

physicians'  responsibility,  1008 

population,  based  on,  989 

registrar,  988,   997 

in    Eome,    988 

of  scarlet  fever,  1006 

of  smallpox,   1002 

source   of   data,    989 

of  states  in  U.  S.  registration  area, 
1018 

of  stillborn,  997 

undertaker's   duty  in,   1020 

value    of,    988 

vitiated,   988 

See  Birth  rates;  Census;  Death 
rates;  Infant  mortality;  Mar- 
riage ;  Morbidity ;  Mortality 
rates;  Notifiable  diseases;  Pop- 
ulation ;  Registration 
Vitamin,  519,  521,  522,  649,  651 
Vitiated  air,  735 

analysis  of,   739 

at  Austerlitz,  736 

at  Black  Hole  of  Calcutta,  736 

cause  of  its  effects,  742 

effects,   extreme,   736 

of   diminished   oxygen,    737 
of  increased  CO^,  737 

physical   changes,    740 

physiological    effects,    735,    742 

poisons  in,   738 

reinspiration  of  expired   air,   742 

summary,   744 

Londondery,  S.8.,   737 
Vitiation,  carbon   dioxid,   as  index  of, 

671 
Vivosphere,  661 
Voges,   260 
Voit,   697 
Volatile   oils,    297 
Voltman,   198 
Volvaria     gloiocephala,     var.     speciosa 

(Fr.),   646 
von  Behring,  547 
von  Drigalski,   123 
von  Ermengen,  539,   626 
von  Freudenreich,  561 
von  Frisch,  533 


von  Hoffman-Wellenhof,  739 
von  Pirquet,    18 
Vosmer,   899 
Vulcanstein,  144 
Vulvovaginitis,    59 

Wade,   163 

Walker,   123,   125,  266,  742,   1111 

Wall   paper,    arsenic   in,    1061 

Walls,    ventilation    through,    760 

Wanderratte,   269 

Ward,  E.   D.,   353,   766 

Ward    family,    479 

Warm,  dry  air,  701 

moist  air,  700 
Warren,  G.,  229 
Warren,  J.  C,  197 
Warthin,   505 
Washburn,  574,   1038 
Washerwomen,   glanders  in,   311 
Washing,    air,    748 
Washington,   flies  and  typhoid   in,   102 

milk-borne    epidemic   in,    100 

typhoid  in,  contact  infection,   104 
and  shellfish,   101 
Wassermann,   429,   445,   452,   469 
Wassermann   reaction,   446 

graphic   representation   of,   447 

in    leprosy,    330 

in  matrimony,   503 
Wasserschen,   39 
Water,    789 

acidity  of,  832 

aeration   of,   827,   853 

algae  in,  805,  824 

allowable    limits    of     impurities    in, 
867 

ammonia,   free,    837 
albuminoid,    841 

amount   necessary,    792 

amount  of,  used  and  wasted,  792 

analysis   of   organic    matter   in,    837 
915 

animal  parasites  in,  947 

aquaphone,    795 

artesian,    797,   812 

bacteriological    examination    of,    858 

as  ballast,  382 

bleaching,  828 

boiled,    882 

bottles    for    samples   of,    822 

calcium   in,    835 

carbonates    in,    834 

as  a  carrier,  of  infection,  912 
of    sewage,   956 

catchment  area,  819 

cement-lined  pipes,   853 

checking  waste,   795 


1284 


INDEX 


Water,  chemical  analysis  of,  821 
expression    of   results,    854 
chlorids  in,  834 

chlorin    in,    interpretation    of,    846 
chlorinated   lime,    1159 
cholera  in,  115,  869,  925 
See  Cholera 
city   supplies,  913 
classification  of,  790 
clinical  experience,   821 
color   of,   828 

to  estimate,  829 
composition    of,    789 
contaminated,   790 
diarrhea  in,  945 
diet  and,   912 
distilled,    882 
double   supplies,    796 
drainage  area,  819 
drinking,  801 
dysentery    in,    944 
effect  of  storage,  875,  877 
epidemics   from   public   supplies,   924 
feces  in,  817 
filter    galleries,    809 
filters   for,   883 
filtration    of,    963 

vs.   sewage  purification,  963 
goiter  and,  917.     See  Goiter 
ground,  806.     See  Ground  water 
hardness  of,  834 

table  of,  836 
industrial    needs,    794 
infant   mortality    and,    914 
infected,   790,   816 

influence  of,  on  typhoid  fever,  95,  932 
inorganic  impurities  of,  817,  916 
iron  in,  852 
to   remove,   853 

Javelle,    1159 

lead     poisoning,     920.       See     Lead 
poisoning 

lime   in,   835 

from  limestone,  810 

magnesium,    835 

malaria  in,  946 

for  manufacturing  needs,  794 

methods    of    analysis,    821 

microscopical  examination  of,  855 

and   military   hygiene,    1204 

in  milk,  598 

Mills-Eeineke  phenomenon,  913 

nitrates  in,   844 

nitrites    in,    842 

nitrogen  in,   837 

non-potable,   790 

non-specific   diseases,   915 

normal,   790 


Water,    odors    of,    805,    823,    827,    857, 
978 
to    determine,    826 
to   prevent,    827 
oils   in,    826 
oxygen  consumed,  848 
oxygen    dissolved,    850,    961 
oxygen  in,  848 
per  capita  consumption,  794 
physical   examination   of,    821 
pitometer,    795 

plumbo-solvent  action   of,  921 
pollution     of,     816.       See     Polluted 

water 
potable,    790 
properties  of,  791 
pure,   790 
purification  of.     See  Purification  of 

water 
putrefactive   index,    849 
quantity  of,   per   day,   792 
for  cities,   793 

rain,  797.     See  Eain  water 
reaction    of,    831 

relation  of,  to  disease,  912 
to  health,  912 

residual    humus    in,    849 

samples  of,  collection  of,  822 

from  sandstone,  810 

sanitary    analysis    of,    821 
interpretation    of,     866 

Sedgwick-Eafter   method,   855 

sediment  in,  829,  896 

sewage  in,  972 

and  smoke,  709 

sodium    chlorid    in,    846 

soft,  797,  802,  834 

in   soil,   772 

sources  of,   796 

specific  diseases  due  to,   923 

spring,   815.     See  Springs 

spring  and  fall  turnover,  805 

sputum  in,   817 

stagnation    of,    805 

storage  of,  804,  819,  896 

storm,  958 

stripping  of,  806 

sulphates  in,   834 

surface,    800.     See   Impounding   res- 
ervoirs ;    Lakes ;    Eivers 

of   swimming  pools,  947 

table    of    amounts    used,    793 

taste    of,    805,    823 

total   solids  in,   833 

trade  wastes  in,   974 

tuberculosis   in,    146,   914 

turbidity  of,  829 

turbidity    standard    of,    831 


INDEX 


1285 


Water,  typhoid  in,  932.     See  Typhoid 

units   of   measurement,    854 

urine    in,    817 

uses  of,  in  body,   791 

wasted,    792,    794 

wastes   in,   817 

wells,  811.     See  Wells 

yellow   fever   and,    947 
Water   analysis,    821 

examples  of,  869 

interpretation    of,    866 
Water  ballast,   cholera  in,   373 
Water-borne  amebic   dysentery,  944 
Water-borne    bacillary    dysentery,    944 
Water-borne    cholera,    116 
Water-borne  diarrhea,  945 
Water-borne  epidemics,  923 
Water-borne  goiter,  in  Vienna,  917 
Water-borne    hookworm,    132 
Water-borne  tuberculosis,  143 
Water-borne  typhoid,   94,   96,   924 

in  Georgetown,  100 

in  Washington,   100 

See  Typhoid  in  water 
Water  carts,  1206 
Water   carriage    system,    956 
Water-closets,    in    schools,    1088 
Water   gas,    724 
Water  meters,  795 
Water  pipes,  lead,  920 

iron,   852 

tubercles  in,  852 
Water-proofing,  1200 
Water-shed,   819 
Water   siphon   method,   672 
Water-troughs,   disinfection   of,    1169 
Water  vapor,  662,  689.     See  Humidity 
Watering,  of  milk,  559,  568 
Watercress,   101 
Waterhouse,  1,  3 
Watertovvn,  typhoid  in,  99 
Wastes,  dye,  974 

petroleum,  974 

solid,   981 

trade,  972,  974 
Watson,    958 
Watsonius  watsoni,  787 
Web  fingers,  499 
Webb,   149 
Weber,    139,    140 
Wechsberg,  449 
Wedgwood,  479 
Weichardt,   459,   740 
Weichselbaum,   145,   198 
Weigert,   409 

Weight,   of   recruits,   1180 
Weigmann,    568 
WaiJ,  17 


Weismann,  471,  484,  515,  740 

Weism.ann's  views,  on  heredity,  484 

Weisner,  306 

Weir,  739 

Welch,  197,  206,  228,  390,  413,  566,  784 

Welch's  gas  bacillus,  784 

Weller,  1050 

Wellman,  653 

Wells,  L.,   77,   188,   351,   359 

Wells,   811 

artesian,  812 

cesspools   and,   978 

composition  of  water  in,  814 

construction  of,  812 

^deep,  812 

disinfection  of,  814,  1176 

driven,   812 

location  of,  814 

near  privies,   976 

near  sewers,  814 

pollution  of,  812 

shallow,   812 
Welsbach  burner,  725 
Werner,   327 

Werner-Schmidt  method,  594 
Wernstedt,    307 

West   African  "relapsing   fever,    293 
Westphal  balance,   599 
Wet  and  cold,  exposure  to,  404 
Wet-bulb   temperature,   698 
Weyl,   T.,   388,   427,    1049,    1072,    1075, 

1098 
Wheeler,   952 
Whentham,  480 
Wherry,    279,   325,   327 
Whipple,  G.  C,  713,  717,  794,  826,  855, 
857,  877,  939,  942,  943,  944,  946, 
953,  981 
White,  61,  242,  323,  333,  359,  360 
AVhite  lead.     See  Lead  poisoning 
White  precipitate,  295 
Whitelegge,  1110 
Whitewash,  1156 
Whitla,    144 
Whittaker,  945 
Whooping  cough,   184 

closing   schools,   186 

death  rates,  173 

immunity  to,   184 

incubation  of,   185 

mental   deficiency   and,   347 

mode    of    transmission,    184 

mortality  of,  186 

prevention  of,   185 

quarantine  in,  185 

vaccines,   186 
Wickman,   304,   307 
Widal,  441,  454 


1286 


INDEX 


Widal   reaction,   93 

Wilbur,  Cressy  L.,  1018 

Wilder,  207,  296 

Wiley,    532,    541,    544,    607,    659 

Williams,  41,  52,   73,   149,  361,  629 

Wilms,  919 

Wilson,  E.  B.,  290,  398,  484,  490,  4^2, 

515 
Wind,  in  sewage  disposal,  974 
Window   ventilators,    760 
Windows,  in  schools,  1086 
Winds,  686 
Winkler,    851 
Winnipeg,  103 
Winogradski,   775,   776 
Winship,  478 
Winslow,   103,  730,  740,  949,  953,  979, 

1045 
Wolbach,    206,    259,    291 
Woll,   580,   604 
Wollstein,    Martha,    187 
Wolpert,  672 
Wolpert  method,   679 
Woman's    milk,    562 
Women,    industrial   hygiene    and,    1042 
Wood,   638,  654,   925 
Wood  alcohol,  70 

chart  insert,   1046 
Wood  dust,  1070 
Wood  lice,  287 

Woodman,   A,  G.,   659,   678,   766 
Woodward,  140,  143 
Wool,  1200 
Wool  sorter's  disease,  316,   1073 

disinfection  of  hides,    1073 

prevention  of,   1073 
Wool    sorter's   pneumonia,    1067,    1073 
Worcester,  Mass.,  sewage  treatment  in, 

966 
Work  hours,  1039 
Workmen 's    compensation,    1045 
Worms,  parasitic,  254 
Worry,   348,   1040 
Wounds,  treatment  of,  rabies,  44 


Wounds,  treatment  of,  tetanus,   76,  81 
Wright,  104,  106,  398,  439,  440,  469 
Wrist   drop,   1049 
Writer's  cramp,  1040 
Wuth,    39 
Wysokowiez,   45 

Xenon,  662 

Xenopsylla  cheopis,  207,  263 
Xenopsylla  cheopis  Eothsc,  262 
X,  Y,  Z  theory  of  cholera,  113 

Yellow  fever,   236 

aerial  conveyance  of,  241 

campaign   against,    in    New    Orleans, 
204 

fomites,    203 

historical  note   on,   242 

immunity   to,   237 

and  malaria  contrasted,  244 

mosquito    and,    201,    202,    206,    237 

prevention  of,  242 

quarantine  against,  375 

in  rain  water,  797 

in  water,  947 
Yersin,    207,    266,    281 
Yersin's  serum,  283 
Yolfert,  20 

York,    J.,    257,    925,    928 
Young,   384,   533,    844,    1070 
Yule,  G.  v.,  1033 

Zable,  1047 
Zammit,  321 
Ziemann,  234 
Zienka,  453 
Zinc,   1055 

industrial  poison,  chart  insert,   1046 
Zinc  chlorid,  1161 
Zingher,  163,  167 
Zinsser,   57 
Zweifel,  73 
Zwischenkorper,  412 
Zygote,  491 

(I) 


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